Imported Upstream version 2.25.3
[platform/upstream/git.git] / sequencer.c
index f2a10cc..df6d18f 100644 (file)
@@ -1,13 +1,14 @@
 #include "cache.h"
 #include "config.h"
 #include "lockfile.h"
-#include "sequencer.h"
 #include "dir.h"
+#include "object-store.h"
 #include "object.h"
 #include "commit.h"
+#include "sequencer.h"
 #include "tag.h"
 #include "run-command.h"
-#include "exec_cmd.h"
+#include "exec-cmd.h"
 #include "utf8.h"
 #include "cache-tree.h"
 #include "diff.h"
 #include "log-tree.h"
 #include "wt-status.h"
 #include "hashmap.h"
+#include "notes-utils.h"
+#include "sigchain.h"
+#include "unpack-trees.h"
+#include "worktree.h"
+#include "oidmap.h"
+#include "oidset.h"
+#include "commit-slab.h"
+#include "alias.h"
+#include "commit-reach.h"
+#include "rebase-interactive.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
-const char sign_off_header[] = "Signed-off-by: ";
+static const char sign_off_header[] = "Signed-off-by: ";
 static const char cherry_picked_prefix[] = "(cherry picked from commit ";
 
+GIT_PATH_FUNC(git_path_commit_editmsg, "COMMIT_EDITMSG")
+
 GIT_PATH_FUNC(git_path_seq_dir, "sequencer")
 
 static GIT_PATH_FUNC(git_path_todo_file, "sequencer/todo")
@@ -41,7 +54,9 @@ static GIT_PATH_FUNC(rebase_path, "rebase-merge")
  * the lines are processed, they are removed from the front of this
  * file and written to the tail of 'done'.
  */
-static GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
+GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
+GIT_PATH_FUNC(rebase_path_todo_backup, "rebase-merge/git-rebase-todo.backup")
+
 /*
  * The rebase command lines that have already been processed. A line
  * is moved here when it is first handled, before any associated user
@@ -52,12 +67,12 @@ static GIT_PATH_FUNC(rebase_path_done, "rebase-merge/done")
  * The file to keep track of how many commands were already processed (e.g.
  * for the prompt).
  */
-static GIT_PATH_FUNC(rebase_path_msgnum, "rebase-merge/msgnum");
+static GIT_PATH_FUNC(rebase_path_msgnum, "rebase-merge/msgnum")
 /*
  * The file to keep track of how many commands are to be processed in total
  * (e.g. for the prompt).
  */
-static GIT_PATH_FUNC(rebase_path_msgtotal, "rebase-merge/end");
+static GIT_PATH_FUNC(rebase_path_msgtotal, "rebase-merge/end")
 /*
  * The commit message that is planned to be used for any changes that
  * need to be committed following a user interaction.
@@ -70,13 +85,6 @@ static GIT_PATH_FUNC(rebase_path_message, "rebase-merge/message")
  * previous commit and from the first squash/fixup commit are written
  * to it. The commit message for each subsequent squash/fixup commit
  * is appended to the file as it is processed.
- *
- * The first line of the file is of the form
- *     # This is a combination of $count commits.
- * where $count is the number of commits whose messages have been
- * written to the file so far (including the initial "pick" commit).
- * Each time that a commit message is processed, this line is read and
- * updated. It is deleted just before the combined commit is made.
  */
 static GIT_PATH_FUNC(rebase_path_squash_msg, "rebase-merge/message-squash")
 /*
@@ -88,6 +96,11 @@ static GIT_PATH_FUNC(rebase_path_squash_msg, "rebase-merge/message-squash")
  */
 static GIT_PATH_FUNC(rebase_path_fixup_msg, "rebase-merge/message-fixup")
 /*
+ * This file contains the list fixup/squash commands that have been
+ * accumulated into message-fixup or message-squash so far.
+ */
+static GIT_PATH_FUNC(rebase_path_current_fixups, "rebase-merge/current-fixups")
+/*
  * A script to set the GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
  * GIT_AUTHOR_DATE that will be used for the commit that is currently
  * being rebased.
@@ -116,19 +129,86 @@ static GIT_PATH_FUNC(rebase_path_stopped_sha, "rebase-merge/stopped-sha")
 static GIT_PATH_FUNC(rebase_path_rewritten_list, "rebase-merge/rewritten-list")
 static GIT_PATH_FUNC(rebase_path_rewritten_pending,
        "rebase-merge/rewritten-pending")
+
+/*
+ * The path of the file containing the OID of the "squash onto" commit, i.e.
+ * the dummy commit used for `reset [new root]`.
+ */
+static GIT_PATH_FUNC(rebase_path_squash_onto, "rebase-merge/squash-onto")
+
+/*
+ * The path of the file listing refs that need to be deleted after the rebase
+ * finishes. This is used by the `label` command to record the need for cleanup.
+ */
+static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
+
 /*
  * The following files are written by git-rebase just after parsing the
- * command-line (and are only consumed, not modified, by the sequencer).
+ * command-line.
  */
 static GIT_PATH_FUNC(rebase_path_gpg_sign_opt, "rebase-merge/gpg_sign_opt")
 static GIT_PATH_FUNC(rebase_path_orig_head, "rebase-merge/orig-head")
 static GIT_PATH_FUNC(rebase_path_verbose, "rebase-merge/verbose")
+static GIT_PATH_FUNC(rebase_path_quiet, "rebase-merge/quiet")
+static GIT_PATH_FUNC(rebase_path_signoff, "rebase-merge/signoff")
 static GIT_PATH_FUNC(rebase_path_head_name, "rebase-merge/head-name")
 static GIT_PATH_FUNC(rebase_path_onto, "rebase-merge/onto")
 static GIT_PATH_FUNC(rebase_path_autostash, "rebase-merge/autostash")
 static GIT_PATH_FUNC(rebase_path_strategy, "rebase-merge/strategy")
 static GIT_PATH_FUNC(rebase_path_strategy_opts, "rebase-merge/strategy_opts")
 static GIT_PATH_FUNC(rebase_path_allow_rerere_autoupdate, "rebase-merge/allow_rerere_autoupdate")
+static GIT_PATH_FUNC(rebase_path_reschedule_failed_exec, "rebase-merge/reschedule-failed-exec")
+
+static int git_sequencer_config(const char *k, const char *v, void *cb)
+{
+       struct replay_opts *opts = cb;
+       int status;
+
+       if (!strcmp(k, "commit.cleanup")) {
+               const char *s;
+
+               status = git_config_string(&s, k, v);
+               if (status)
+                       return status;
+
+               if (!strcmp(s, "verbatim")) {
+                       opts->default_msg_cleanup = COMMIT_MSG_CLEANUP_NONE;
+                       opts->explicit_cleanup = 1;
+               } else if (!strcmp(s, "whitespace")) {
+                       opts->default_msg_cleanup = COMMIT_MSG_CLEANUP_SPACE;
+                       opts->explicit_cleanup = 1;
+               } else if (!strcmp(s, "strip")) {
+                       opts->default_msg_cleanup = COMMIT_MSG_CLEANUP_ALL;
+                       opts->explicit_cleanup = 1;
+               } else if (!strcmp(s, "scissors")) {
+                       opts->default_msg_cleanup = COMMIT_MSG_CLEANUP_SCISSORS;
+                       opts->explicit_cleanup = 1;
+               } else {
+                       warning(_("invalid commit message cleanup mode '%s'"),
+                                 s);
+               }
+
+               free((char *)s);
+               return status;
+       }
+
+       if (!strcmp(k, "commit.gpgsign")) {
+               opts->gpg_sign = git_config_bool(k, v) ? xstrdup("") : NULL;
+               return 0;
+       }
+
+       status = git_gpg_config(k, v, NULL);
+       if (status)
+               return status;
+
+       return git_diff_basic_config(k, v, NULL);
+}
+
+void sequencer_init_config(struct replay_opts *opts)
+{
+       opts->default_msg_cleanup = COMMIT_MSG_CLEANUP_NONE;
+       git_config(git_sequencer_config, opts);
+}
 
 static inline int is_rebase_i(const struct replay_opts *opts)
 {
@@ -156,13 +236,16 @@ static const char *get_todo_path(const struct replay_opts *opts)
  * Returns 3 when sob exists within conforming footer as last entry
  */
 static int has_conforming_footer(struct strbuf *sb, struct strbuf *sob,
-       int ignore_footer)
+       size_t ignore_footer)
 {
+       struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
        struct trailer_info info;
-       int i;
+       size_t i;
        int found_sob = 0, found_sob_last = 0;
 
-       trailer_info_get(&info, sb->buf);
+       opts.no_divider = 1;
+
+       trailer_info_get(&info, sb->buf, &opts);
 
        if (info.trailer_start == info.trailer_end)
                return 0;
@@ -195,20 +278,40 @@ static const char *gpg_sign_opt_quoted(struct replay_opts *opts)
 
 int sequencer_remove_state(struct replay_opts *opts)
 {
-       struct strbuf dir = STRBUF_INIT;
-       int i;
+       struct strbuf buf = STRBUF_INIT;
+       int i, ret = 0;
+
+       if (is_rebase_i(opts) &&
+           strbuf_read_file(&buf, rebase_path_refs_to_delete(), 0) > 0) {
+               char *p = buf.buf;
+               while (*p) {
+                       char *eol = strchr(p, '\n');
+                       if (eol)
+                               *eol = '\0';
+                       if (delete_ref("(rebase -i) cleanup", p, NULL, 0) < 0) {
+                               warning(_("could not delete '%s'"), p);
+                               ret = -1;
+                       }
+                       if (!eol)
+                               break;
+                       p = eol + 1;
+               }
+       }
 
        free(opts->gpg_sign);
        free(opts->strategy);
        for (i = 0; i < opts->xopts_nr; i++)
                free(opts->xopts[i]);
        free(opts->xopts);
+       strbuf_release(&opts->current_fixups);
 
-       strbuf_addstr(&dir, get_dir(opts));
-       remove_dir_recursively(&dir, 0);
-       strbuf_release(&dir);
+       strbuf_reset(&buf);
+       strbuf_addstr(&buf, get_dir(opts));
+       if (remove_dir_recursively(&buf, 0))
+               ret = error(_("could not remove '%s'"), buf.buf);
+       strbuf_release(&buf);
 
-       return 0;
+       return ret;
 }
 
 static const char *action_name(const struct replay_opts *opts)
@@ -221,7 +324,7 @@ static const char *action_name(const struct replay_opts *opts)
        case REPLAY_INTERACTIVE_REBASE:
                return N_("rebase -i");
        }
-       die(_("Unknown action: %d"), opts->action);
+       die(_("unknown action: %d"), opts->action);
 }
 
 struct commit_message {
@@ -233,7 +336,7 @@ struct commit_message {
 
 static const char *short_commit_name(struct commit *commit)
 {
-       return find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV);
+       return find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV);
 }
 
 static int get_message(struct commit *commit, struct commit_message *out)
@@ -261,7 +364,8 @@ static void free_message(struct commit *commit, struct commit_message *msg)
        unuse_commit_buffer(commit, msg->message);
 }
 
-static void print_advice(int show_hint, struct replay_opts *opts)
+static void print_advice(struct repository *r, int show_hint,
+                        struct replay_opts *opts)
 {
        char *msg = getenv("GIT_CHERRY_PICK_HELP");
 
@@ -272,7 +376,7 @@ static void print_advice(int show_hint, struct replay_opts *opts)
                 * (typically rebase --interactive) wants to take care
                 * of the commit itself so remove CHERRY_PICK_HEAD
                 */
-               unlink(git_path_cherry_pick_head());
+               unlink(git_path_cherry_pick_head(r));
                return;
        }
 
@@ -290,23 +394,23 @@ static void print_advice(int show_hint, struct replay_opts *opts)
 static int write_message(const void *buf, size_t len, const char *filename,
                         int append_eol)
 {
-       static struct lock_file msg_file;
+       struct lock_file msg_file = LOCK_INIT;
 
        int msg_fd = hold_lock_file_for_update(&msg_file, filename, 0);
        if (msg_fd < 0)
                return error_errno(_("could not lock '%s'"), filename);
        if (write_in_full(msg_fd, buf, len) < 0) {
+               error_errno(_("could not write to '%s'"), filename);
                rollback_lock_file(&msg_file);
-               return error_errno(_("could not write to '%s'"), filename);
+               return -1;
        }
        if (append_eol && write(msg_fd, "\n", 1) < 0) {
+               error_errno(_("could not write eol to '%s'"), filename);
                rollback_lock_file(&msg_file);
-               return error_errno(_("could not write eol to '%s'"), filename);
-       }
-       if (commit_lock_file(&msg_file) < 0) {
-               rollback_lock_file(&msg_file);
-               return error(_("failed to finalize '%s'."), filename);
+               return -1;
        }
+       if (commit_lock_file(&msg_file) < 0)
+               return error(_("failed to finalize '%s'"), filename);
 
        return 0;
 }
@@ -345,14 +449,14 @@ static int read_oneliner(struct strbuf *buf,
        return 1;
 }
 
-static struct tree *empty_tree(void)
+static struct tree *empty_tree(struct repository *r)
 {
-       return lookup_tree(&empty_tree_oid);
+       return lookup_tree(r, the_hash_algo->empty_tree);
 }
 
-static int error_dirty_index(struct replay_opts *opts)
+static int error_dirty_index(struct repository *repo, struct replay_opts *opts)
 {
-       if (read_cache_unmerged())
+       if (repo_read_index_unmerged(repo))
                return error_resolve_conflict(_(action_name(opts)));
 
        error(_("your local changes would be overwritten by %s."),
@@ -377,15 +481,18 @@ static void update_abort_safety_file(void)
                write_file(git_path_abort_safety_file(), "%s", "");
 }
 
-static int fast_forward_to(const struct object_id *to, const struct object_id *from,
-                       int unborn, struct replay_opts *opts)
+static int fast_forward_to(struct repository *r,
+                          const struct object_id *to,
+                          const struct object_id *from,
+                          int unborn,
+                          struct replay_opts *opts)
 {
        struct ref_transaction *transaction;
        struct strbuf sb = STRBUF_INIT;
        struct strbuf err = STRBUF_INIT;
 
-       read_cache();
-       if (checkout_fast_forward(from, to, 1))
+       repo_read_index(r);
+       if (checkout_fast_forward(r, from, to, 1))
                return -1; /* the callee should have complained already */
 
        strbuf_addf(&sb, _("%s: fast-forward"), _(action_name(opts)));
@@ -393,7 +500,8 @@ static int fast_forward_to(const struct object_id *to, const struct object_id *f
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_update(transaction, "HEAD",
-                                  to->hash, unborn ? null_sha1 : from->hash,
+                                  to, unborn && !is_rebase_i(opts) ?
+                                  &null_oid : from,
                                   0, sb.buf, &err) ||
            ref_transaction_commit(transaction, &err)) {
                ref_transaction_free(transaction);
@@ -410,89 +518,150 @@ static int fast_forward_to(const struct object_id *to, const struct object_id *f
        return 0;
 }
 
-void append_conflicts_hint(struct strbuf *msgbuf)
+enum commit_msg_cleanup_mode get_cleanup_mode(const char *cleanup_arg,
+       int use_editor)
+{
+       if (!cleanup_arg || !strcmp(cleanup_arg, "default"))
+               return use_editor ? COMMIT_MSG_CLEANUP_ALL :
+                                   COMMIT_MSG_CLEANUP_SPACE;
+       else if (!strcmp(cleanup_arg, "verbatim"))
+               return COMMIT_MSG_CLEANUP_NONE;
+       else if (!strcmp(cleanup_arg, "whitespace"))
+               return COMMIT_MSG_CLEANUP_SPACE;
+       else if (!strcmp(cleanup_arg, "strip"))
+               return COMMIT_MSG_CLEANUP_ALL;
+       else if (!strcmp(cleanup_arg, "scissors"))
+               return use_editor ? COMMIT_MSG_CLEANUP_SCISSORS :
+                                   COMMIT_MSG_CLEANUP_SPACE;
+       else
+               die(_("Invalid cleanup mode %s"), cleanup_arg);
+}
+
+/*
+ * NB using int rather than enum cleanup_mode to stop clang's
+ * -Wtautological-constant-out-of-range-compare complaining that the comparison
+ * is always true.
+ */
+static const char *describe_cleanup_mode(int cleanup_mode)
+{
+       static const char *modes[] = { "whitespace",
+                                      "verbatim",
+                                      "scissors",
+                                      "strip" };
+
+       if (cleanup_mode < ARRAY_SIZE(modes))
+               return modes[cleanup_mode];
+
+       BUG("invalid cleanup_mode provided (%d)", cleanup_mode);
+}
+
+void append_conflicts_hint(struct index_state *istate,
+       struct strbuf *msgbuf, enum commit_msg_cleanup_mode cleanup_mode)
 {
        int i;
 
+       if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS) {
+               strbuf_addch(msgbuf, '\n');
+               wt_status_append_cut_line(msgbuf);
+               strbuf_addch(msgbuf, comment_line_char);
+       }
+
        strbuf_addch(msgbuf, '\n');
        strbuf_commented_addf(msgbuf, "Conflicts:\n");
-       for (i = 0; i < active_nr;) {
-               const struct cache_entry *ce = active_cache[i++];
+       for (i = 0; i < istate->cache_nr;) {
+               const struct cache_entry *ce = istate->cache[i++];
                if (ce_stage(ce)) {
                        strbuf_commented_addf(msgbuf, "\t%s\n", ce->name);
-                       while (i < active_nr && !strcmp(ce->name,
-                                                       active_cache[i]->name))
+                       while (i < istate->cache_nr &&
+                              !strcmp(ce->name, istate->cache[i]->name))
                                i++;
                }
        }
 }
 
-static int do_recursive_merge(struct commit *base, struct commit *next,
+static int do_recursive_merge(struct repository *r,
+                             struct commit *base, struct commit *next,
                              const char *base_label, const char *next_label,
                              struct object_id *head, struct strbuf *msgbuf,
                              struct replay_opts *opts)
 {
        struct merge_options o;
-       struct tree *result, *next_tree, *base_tree, *head_tree;
+       struct tree *next_tree, *base_tree, *head_tree;
        int clean;
-       char **xopt;
-       static struct lock_file index_lock;
+       int i;
+       struct lock_file index_lock = LOCK_INIT;
 
-       hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
+       if (repo_hold_locked_index(r, &index_lock, LOCK_REPORT_ON_ERROR) < 0)
+               return -1;
 
-       read_cache();
+       repo_read_index(r);
 
-       init_merge_options(&o);
+       init_merge_options(&o, r);
        o.ancestor = base ? base_label : "(empty tree)";
        o.branch1 = "HEAD";
        o.branch2 = next ? next_label : "(empty tree)";
        if (is_rebase_i(opts))
                o.buffer_output = 2;
+       o.show_rename_progress = 1;
 
        head_tree = parse_tree_indirect(head);
-       next_tree = next ? next->tree : empty_tree();
-       base_tree = base ? base->tree : empty_tree();
+       next_tree = next ? get_commit_tree(next) : empty_tree(r);
+       base_tree = base ? get_commit_tree(base) : empty_tree(r);
 
-       for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
-               parse_merge_opt(&o, *xopt);
+       for (i = 0; i < opts->xopts_nr; i++)
+               parse_merge_opt(&o, opts->xopts[i]);
 
        clean = merge_trees(&o,
                            head_tree,
-                           next_tree, base_tree, &result);
+                           next_tree, base_tree);
        if (is_rebase_i(opts) && clean <= 0)
                fputs(o.obuf.buf, stdout);
        strbuf_release(&o.obuf);
-       if (clean < 0)
+       if (clean < 0) {
+               rollback_lock_file(&index_lock);
                return clean;
+       }
 
-       if (active_cache_changed &&
-           write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
+       if (write_locked_index(r->index, &index_lock,
+                              COMMIT_LOCK | SKIP_IF_UNCHANGED))
                /*
                 * TRANSLATORS: %s will be "revert", "cherry-pick" or
                 * "rebase -i".
                 */
                return error(_("%s: Unable to write new index file"),
                        _(action_name(opts)));
-       rollback_lock_file(&index_lock);
-
-       if (opts->signoff)
-               append_signoff(msgbuf, 0, 0);
 
        if (!clean)
-               append_conflicts_hint(msgbuf);
+               append_conflicts_hint(r->index, msgbuf,
+                                     opts->default_msg_cleanup);
 
        return !clean;
 }
 
-static int is_index_unchanged(void)
+static struct object_id *get_cache_tree_oid(struct index_state *istate)
 {
-       struct object_id head_oid;
+       if (!istate->cache_tree)
+               istate->cache_tree = cache_tree();
+
+       if (!cache_tree_fully_valid(istate->cache_tree))
+               if (cache_tree_update(istate, 0)) {
+                       error(_("unable to update cache tree"));
+                       return NULL;
+               }
+
+       return &istate->cache_tree->oid;
+}
+
+static int is_index_unchanged(struct repository *r)
+{
+       struct object_id head_oid, *cache_tree_oid;
        struct commit *head_commit;
+       struct index_state *istate = r->index;
 
-       if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, head_oid.hash, NULL))
-               return error(_("could not resolve HEAD commit\n"));
+       if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
+               return error(_("could not resolve HEAD commit"));
 
-       head_commit = lookup_commit(&head_oid);
+       head_commit = lookup_commit(r, &head_oid);
 
        /*
         * If head_commit is NULL, check_commit, called from
@@ -505,15 +674,10 @@ static int is_index_unchanged(void)
        if (parse_commit(head_commit))
                return -1;
 
-       if (!active_cache_tree)
-               active_cache_tree = cache_tree();
-
-       if (!cache_tree_fully_valid(active_cache_tree))
-               if (cache_tree_update(&the_index, 0))
-                       return error(_("unable to update cache tree\n"));
+       if (!(cache_tree_oid = get_cache_tree_oid(istate)))
+               return -1;
 
-       return !oidcmp(&active_cache_tree->oid,
-                      &head_commit->tree->object.oid);
+       return oideq(cache_tree_oid, get_commit_tree_oid(head_commit));
 }
 
 static int write_author_script(const char *message)
@@ -542,7 +706,7 @@ missing_author:
                else if (*message != '\'')
                        strbuf_addch(&buf, *(message++));
                else
-                       strbuf_addf(&buf, "'\\\\%c'", *(message++));
+                       strbuf_addf(&buf, "'\\%c'", *(message++));
        strbuf_addstr(&buf, "'\nGIT_AUTHOR_EMAIL='");
        while (*message && *message != '\n' && *message != '\r')
                if (skip_prefix(message, "> ", &message))
@@ -550,49 +714,160 @@ missing_author:
                else if (*message != '\'')
                        strbuf_addch(&buf, *(message++));
                else
-                       strbuf_addf(&buf, "'\\\\%c'", *(message++));
+                       strbuf_addf(&buf, "'\\%c'", *(message++));
        strbuf_addstr(&buf, "'\nGIT_AUTHOR_DATE='@");
        while (*message && *message != '\n' && *message != '\r')
                if (*message != '\'')
                        strbuf_addch(&buf, *(message++));
                else
-                       strbuf_addf(&buf, "'\\\\%c'", *(message++));
+                       strbuf_addf(&buf, "'\\%c'", *(message++));
+       strbuf_addch(&buf, '\'');
        res = write_message(buf.buf, buf.len, rebase_path_author_script(), 1);
        strbuf_release(&buf);
        return res;
 }
 
+/**
+ * Take a series of KEY='VALUE' lines where VALUE part is
+ * sq-quoted, and append <KEY, VALUE> at the end of the string list
+ */
+static int parse_key_value_squoted(char *buf, struct string_list *list)
+{
+       while (*buf) {
+               struct string_list_item *item;
+               char *np;
+               char *cp = strchr(buf, '=');
+               if (!cp) {
+                       np = strchrnul(buf, '\n');
+                       return error(_("no key present in '%.*s'"),
+                                    (int) (np - buf), buf);
+               }
+               np = strchrnul(cp, '\n');
+               *cp++ = '\0';
+               item = string_list_append(list, buf);
+
+               buf = np + (*np == '\n');
+               *np = '\0';
+               cp = sq_dequote(cp);
+               if (!cp)
+                       return error(_("unable to dequote value of '%s'"),
+                                    item->string);
+               item->util = xstrdup(cp);
+       }
+       return 0;
+}
+
+/**
+ * Reads and parses the state directory's "author-script" file, and sets name,
+ * email and date accordingly.
+ * Returns 0 on success, -1 if the file could not be parsed.
+ *
+ * The author script is of the format:
+ *
+ *     GIT_AUTHOR_NAME='$author_name'
+ *     GIT_AUTHOR_EMAIL='$author_email'
+ *     GIT_AUTHOR_DATE='$author_date'
+ *
+ * where $author_name, $author_email and $author_date are quoted. We are strict
+ * with our parsing, as the file was meant to be eval'd in the now-removed
+ * git-am.sh/git-rebase--interactive.sh scripts, and thus if the file differs
+ * from what this function expects, it is better to bail out than to do
+ * something that the user does not expect.
+ */
+int read_author_script(const char *path, char **name, char **email, char **date,
+                      int allow_missing)
+{
+       struct strbuf buf = STRBUF_INIT;
+       struct string_list kv = STRING_LIST_INIT_DUP;
+       int retval = -1; /* assume failure */
+       int i, name_i = -2, email_i = -2, date_i = -2, err = 0;
+
+       if (strbuf_read_file(&buf, path, 256) <= 0) {
+               strbuf_release(&buf);
+               if (errno == ENOENT && allow_missing)
+                       return 0;
+               else
+                       return error_errno(_("could not open '%s' for reading"),
+                                          path);
+       }
+
+       if (parse_key_value_squoted(buf.buf, &kv))
+               goto finish;
+
+       for (i = 0; i < kv.nr; i++) {
+               if (!strcmp(kv.items[i].string, "GIT_AUTHOR_NAME")) {
+                       if (name_i != -2)
+                               name_i = error(_("'GIT_AUTHOR_NAME' already given"));
+                       else
+                               name_i = i;
+               } else if (!strcmp(kv.items[i].string, "GIT_AUTHOR_EMAIL")) {
+                       if (email_i != -2)
+                               email_i = error(_("'GIT_AUTHOR_EMAIL' already given"));
+                       else
+                               email_i = i;
+               } else if (!strcmp(kv.items[i].string, "GIT_AUTHOR_DATE")) {
+                       if (date_i != -2)
+                               date_i = error(_("'GIT_AUTHOR_DATE' already given"));
+                       else
+                               date_i = i;
+               } else {
+                       err = error(_("unknown variable '%s'"),
+                                   kv.items[i].string);
+               }
+       }
+       if (name_i == -2)
+               error(_("missing 'GIT_AUTHOR_NAME'"));
+       if (email_i == -2)
+               error(_("missing 'GIT_AUTHOR_EMAIL'"));
+       if (date_i == -2)
+               error(_("missing 'GIT_AUTHOR_DATE'"));
+       if (date_i < 0 || email_i < 0 || date_i < 0 || err)
+               goto finish;
+       *name = kv.items[name_i].util;
+       *email = kv.items[email_i].util;
+       *date = kv.items[date_i].util;
+       retval = 0;
+finish:
+       string_list_clear(&kv, !!retval);
+       strbuf_release(&buf);
+       return retval;
+}
+
 /*
- * Read a list of environment variable assignments (such as the author-script
- * file) into an environment block. Returns -1 on error, 0 otherwise.
+ * Read a GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL AND GIT_AUTHOR_DATE from a
+ * file with shell quoting into struct argv_array. Returns -1 on
+ * error, 0 otherwise.
  */
 static int read_env_script(struct argv_array *env)
 {
-       struct strbuf script = STRBUF_INIT;
-       int i, count = 0;
-       char *p, *p2;
+       char *name, *email, *date;
 
-       if (strbuf_read_file(&script, rebase_path_author_script(), 256) <= 0)
+       if (read_author_script(rebase_path_author_script(),
+                              &name, &email, &date, 0))
                return -1;
 
-       for (p = script.buf; *p; p++)
-               if (skip_prefix(p, "'\\\\''", (const char **)&p2))
-                       strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
-               else if (*p == '\'')
-                       strbuf_splice(&script, p-- - script.buf, 1, "", 0);
-               else if (*p == '\n') {
-                       *p = '\0';
-                       count++;
-               }
-
-       for (i = 0, p = script.buf; i < count; i++) {
-               argv_array_push(env, p);
-               p += strlen(p) + 1;
-       }
+       argv_array_pushf(env, "GIT_AUTHOR_NAME=%s", name);
+       argv_array_pushf(env, "GIT_AUTHOR_EMAIL=%s", email);
+       argv_array_pushf(env, "GIT_AUTHOR_DATE=%s", date);
+       free(name);
+       free(email);
+       free(date);
 
        return 0;
 }
 
+static char *get_author(const char *message)
+{
+       size_t len;
+       const char *a;
+
+       a = find_commit_header(message, "author", &len);
+       if (a)
+               return xmemdupz(a, len);
+
+       return NULL;
+}
+
 static const char staged_changes_advice[] =
 N_("you have staged changes in your working tree\n"
 "If these changes are meant to be squashed into the previous commit, run:\n"
@@ -612,6 +887,24 @@ N_("you have staged changes in your working tree\n"
 #define AMEND_MSG   (1<<2)
 #define CLEANUP_MSG (1<<3)
 #define VERIFY_MSG  (1<<4)
+#define CREATE_ROOT_COMMIT (1<<5)
+
+static int run_command_silent_on_success(struct child_process *cmd)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int rc;
+
+       cmd->stdout_to_stderr = 1;
+       rc = pipe_command(cmd,
+                         NULL, 0,
+                         NULL, 0,
+                         &buf, 0);
+
+       if (rc)
+               fputs(buf.buf, stderr);
+       strbuf_release(&buf);
+       return rc;
+}
 
 /*
  * If we are cherry-pick, and if the merge did not result in
@@ -625,26 +918,20 @@ N_("you have staged changes in your working tree\n"
  * interactive rebase: in that case, we will want to retain the
  * author metadata.
  */
-static int run_git_commit(const char *defmsg, struct replay_opts *opts,
+static int run_git_commit(struct repository *r,
+                         const char *defmsg,
+                         struct replay_opts *opts,
                          unsigned int flags)
 {
        struct child_process cmd = CHILD_PROCESS_INIT;
-       const char *value;
 
        cmd.git_cmd = 1;
 
-       if (is_rebase_i(opts)) {
-               if (!(flags & EDIT_MSG)) {
-                       cmd.stdout_to_stderr = 1;
-                       cmd.err = -1;
-               }
-
-               if (read_env_script(&cmd.env_array)) {
-                       const char *gpg_opt = gpg_sign_opt_quoted(opts);
+       if (is_rebase_i(opts) && read_env_script(&cmd.env_array)) {
+               const char *gpg_opt = gpg_sign_opt_quoted(opts);
 
-                       return error(_(staged_changes_advice),
-                                    gpg_opt, gpg_opt);
-               }
+               return error(_(staged_changes_advice),
+                            gpg_opt, gpg_opt);
        }
 
        argv_array_push(&cmd.args, "commit");
@@ -655,213 +942,694 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
                argv_array_push(&cmd.args, "--amend");
        if (opts->gpg_sign)
                argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
-       if (opts->signoff)
-               argv_array_push(&cmd.args, "-s");
        if (defmsg)
                argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
+       else if (!(flags & EDIT_MSG))
+               argv_array_pushl(&cmd.args, "-C", "HEAD", NULL);
        if ((flags & CLEANUP_MSG))
                argv_array_push(&cmd.args, "--cleanup=strip");
        if ((flags & EDIT_MSG))
                argv_array_push(&cmd.args, "-e");
        else if (!(flags & CLEANUP_MSG) &&
                 !opts->signoff && !opts->record_origin &&
-                git_config_get_value("commit.cleanup", &value))
+                !opts->explicit_cleanup)
                argv_array_push(&cmd.args, "--cleanup=verbatim");
 
        if ((flags & ALLOW_EMPTY))
                argv_array_push(&cmd.args, "--allow-empty");
 
-       if (opts->allow_empty_message)
+       if (!(flags & EDIT_MSG))
                argv_array_push(&cmd.args, "--allow-empty-message");
 
-       if (cmd.err == -1) {
-               /* hide stderr on success */
-               struct strbuf buf = STRBUF_INIT;
-               int rc = pipe_command(&cmd,
-                                     NULL, 0,
-                                     /* stdout is already redirected */
-                                     NULL, 0,
-                                     &buf, 0);
-               if (rc)
-                       fputs(buf.buf, stderr);
-               strbuf_release(&buf);
-               return rc;
-       }
-
-       return run_command(&cmd);
+       if (is_rebase_i(opts) && !(flags & EDIT_MSG))
+               return run_command_silent_on_success(&cmd);
+       else
+               return run_command(&cmd);
 }
 
-static int is_original_commit_empty(struct commit *commit)
+static int rest_is_empty(const struct strbuf *sb, int start)
 {
-       const struct object_id *ptree_oid;
+       int i, eol;
+       const char *nl;
+
+       /* Check if the rest is just whitespace and Signed-off-by's. */
+       for (i = start; i < sb->len; i++) {
+               nl = memchr(sb->buf + i, '\n', sb->len - i);
+               if (nl)
+                       eol = nl - sb->buf;
+               else
+                       eol = sb->len;
 
-       if (parse_commit(commit))
-               return error(_("could not parse commit %s\n"),
-                            oid_to_hex(&commit->object.oid));
-       if (commit->parents) {
-               struct commit *parent = commit->parents->item;
-               if (parse_commit(parent))
-                       return error(_("could not parse parent commit %s\n"),
-                               oid_to_hex(&parent->object.oid));
-               ptree_oid = &parent->tree->object.oid;
-       } else {
-               ptree_oid = &empty_tree_oid; /* commit is root */
+               if (strlen(sign_off_header) <= eol - i &&
+                   starts_with(sb->buf + i, sign_off_header)) {
+                       i = eol;
+                       continue;
+               }
+               while (i < eol)
+                       if (!isspace(sb->buf[i++]))
+                               return 0;
        }
 
-       return !oidcmp(ptree_oid, &commit->tree->object.oid);
+       return 1;
+}
+
+void cleanup_message(struct strbuf *msgbuf,
+       enum commit_msg_cleanup_mode cleanup_mode, int verbose)
+{
+       if (verbose || /* Truncate the message just before the diff, if any. */
+           cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS)
+               strbuf_setlen(msgbuf, wt_status_locate_end(msgbuf->buf, msgbuf->len));
+       if (cleanup_mode != COMMIT_MSG_CLEANUP_NONE)
+               strbuf_stripspace(msgbuf, cleanup_mode == COMMIT_MSG_CLEANUP_ALL);
 }
 
 /*
- * Do we run "git commit" with "--allow-empty"?
+ * Find out if the message in the strbuf contains only whitespace and
+ * Signed-off-by lines.
  */
-static int allow_empty(struct replay_opts *opts, struct commit *commit)
+int message_is_empty(const struct strbuf *sb,
+                    enum commit_msg_cleanup_mode cleanup_mode)
 {
-       int index_unchanged, empty_commit;
-
-       /*
-        * Three cases:
-        *
-        * (1) we do not allow empty at all and error out.
-        *
-        * (2) we allow ones that were initially empty, but
-        * forbid the ones that become empty;
-        *
-        * (3) we allow both.
-        */
-       if (!opts->allow_empty)
-               return 0; /* let "git commit" barf as necessary */
-
-       index_unchanged = is_index_unchanged();
-       if (index_unchanged < 0)
-               return index_unchanged;
-       if (!index_unchanged)
-               return 0; /* we do not have to say --allow-empty */
-
-       if (opts->keep_redundant_commits)
-               return 1;
-
-       empty_commit = is_original_commit_empty(commit);
-       if (empty_commit < 0)
-               return empty_commit;
-       if (!empty_commit)
+       if (cleanup_mode == COMMIT_MSG_CLEANUP_NONE && sb->len)
                return 0;
-       else
-               return 1;
+       return rest_is_empty(sb, 0);
 }
 
 /*
- * Note that ordering matters in this enum. Not only must it match the mapping
- * below, it is also divided into several sections that matter.  When adding
- * new commands, make sure you add it in the right section.
+ * See if the user edited the message in the editor or left what
+ * was in the template intact
  */
-enum todo_command {
-       /* commands that handle commits */
-       TODO_PICK = 0,
-       TODO_REVERT,
-       TODO_EDIT,
-       TODO_REWORD,
-       TODO_FIXUP,
-       TODO_SQUASH,
-       /* commands that do something else than handling a single commit */
-       TODO_EXEC,
-       /* commands that do nothing but are counted for reporting progress */
-       TODO_NOOP,
-       TODO_DROP,
-       /* comments (not counted for reporting progress) */
-       TODO_COMMENT
-};
+int template_untouched(const struct strbuf *sb, const char *template_file,
+                      enum commit_msg_cleanup_mode cleanup_mode)
+{
+       struct strbuf tmpl = STRBUF_INIT;
+       const char *start;
 
-static struct {
-       char c;
-       const char *str;
-} todo_command_info[] = {
-       { 'p', "pick" },
-       { 0,   "revert" },
-       { 'e', "edit" },
-       { 'r', "reword" },
-       { 'f', "fixup" },
-       { 's', "squash" },
-       { 'x', "exec" },
-       { 0,   "noop" },
-       { 'd', "drop" },
-       { 0,   NULL }
-};
+       if (cleanup_mode == COMMIT_MSG_CLEANUP_NONE && sb->len)
+               return 0;
 
-static const char *command_to_string(const enum todo_command command)
-{
-       if (command < TODO_COMMENT)
-               return todo_command_info[command].str;
-       die("Unknown command: %d", command);
+       if (!template_file || strbuf_read_file(&tmpl, template_file, 0) <= 0)
+               return 0;
+
+       strbuf_stripspace(&tmpl, cleanup_mode == COMMIT_MSG_CLEANUP_ALL);
+       if (!skip_prefix(sb->buf, tmpl.buf, &start))
+               start = sb->buf;
+       strbuf_release(&tmpl);
+       return rest_is_empty(sb, start - sb->buf);
 }
 
-static int is_noop(const enum todo_command command)
+int update_head_with_reflog(const struct commit *old_head,
+                           const struct object_id *new_head,
+                           const char *action, const struct strbuf *msg,
+                           struct strbuf *err)
 {
-       return TODO_NOOP <= command;
+       struct ref_transaction *transaction;
+       struct strbuf sb = STRBUF_INIT;
+       const char *nl;
+       int ret = 0;
+
+       if (action) {
+               strbuf_addstr(&sb, action);
+               strbuf_addstr(&sb, ": ");
+       }
+
+       nl = strchr(msg->buf, '\n');
+       if (nl) {
+               strbuf_add(&sb, msg->buf, nl + 1 - msg->buf);
+       } else {
+               strbuf_addbuf(&sb, msg);
+               strbuf_addch(&sb, '\n');
+       }
+
+       transaction = ref_transaction_begin(err);
+       if (!transaction ||
+           ref_transaction_update(transaction, "HEAD", new_head,
+                                  old_head ? &old_head->object.oid : &null_oid,
+                                  0, sb.buf, err) ||
+           ref_transaction_commit(transaction, err)) {
+               ret = -1;
+       }
+       ref_transaction_free(transaction);
+       strbuf_release(&sb);
+
+       return ret;
 }
 
-static int is_fixup(enum todo_command command)
+static int run_rewrite_hook(const struct object_id *oldoid,
+                           const struct object_id *newoid)
 {
-       return command == TODO_FIXUP || command == TODO_SQUASH;
+       struct child_process proc = CHILD_PROCESS_INIT;
+       const char *argv[3];
+       int code;
+       struct strbuf sb = STRBUF_INIT;
+
+       argv[0] = find_hook("post-rewrite");
+       if (!argv[0])
+               return 0;
+
+       argv[1] = "amend";
+       argv[2] = NULL;
+
+       proc.argv = argv;
+       proc.in = -1;
+       proc.stdout_to_stderr = 1;
+       proc.trace2_hook_name = "post-rewrite";
+
+       code = start_command(&proc);
+       if (code)
+               return code;
+       strbuf_addf(&sb, "%s %s\n", oid_to_hex(oldoid), oid_to_hex(newoid));
+       sigchain_push(SIGPIPE, SIG_IGN);
+       write_in_full(proc.in, sb.buf, sb.len);
+       close(proc.in);
+       strbuf_release(&sb);
+       sigchain_pop(SIGPIPE);
+       return finish_command(&proc);
 }
 
-static int update_squash_messages(enum todo_command command,
-               struct commit *commit, struct replay_opts *opts)
+void commit_post_rewrite(struct repository *r,
+                        const struct commit *old_head,
+                        const struct object_id *new_head)
 {
-       struct strbuf buf = STRBUF_INIT;
-       int count, res;
-       const char *message, *body;
-
-       if (file_exists(rebase_path_squash_msg())) {
-               struct strbuf header = STRBUF_INIT;
-               char *eol, *p;
+       struct notes_rewrite_cfg *cfg;
 
-               if (strbuf_read_file(&buf, rebase_path_squash_msg(), 2048) <= 0)
-                       return error(_("could not read '%s'"),
-                               rebase_path_squash_msg());
+       cfg = init_copy_notes_for_rewrite("amend");
+       if (cfg) {
+               /* we are amending, so old_head is not NULL */
+               copy_note_for_rewrite(cfg, &old_head->object.oid, new_head);
+               finish_copy_notes_for_rewrite(r, cfg, "Notes added by 'git commit --amend'");
+       }
+       run_rewrite_hook(&old_head->object.oid, new_head);
+}
 
-               p = buf.buf + 1;
-               eol = strchrnul(buf.buf, '\n');
-               if (buf.buf[0] != comment_line_char ||
-                   (p += strcspn(p, "0123456789\n")) == eol)
-                       return error(_("unexpected 1st line of squash message:"
-                                      "\n\n\t%.*s"),
-                                    (int)(eol - buf.buf), buf.buf);
-               count = strtol(p, NULL, 10);
+static int run_prepare_commit_msg_hook(struct repository *r,
+                                      struct strbuf *msg,
+                                      const char *commit)
+{
+       int ret = 0;
+       const char *name, *arg1 = NULL, *arg2 = NULL;
 
-               if (count < 1)
-                       return error(_("invalid 1st line of squash message:\n"
-                                      "\n\t%.*s"),
-                                    (int)(eol - buf.buf), buf.buf);
+       name = git_path_commit_editmsg();
+       if (write_message(msg->buf, msg->len, name, 0))
+               return -1;
 
-               strbuf_addf(&header, "%c ", comment_line_char);
-               strbuf_addf(&header,
-                           _("This is a combination of %d commits."), ++count);
-               strbuf_splice(&buf, 0, eol - buf.buf, header.buf, header.len);
-               strbuf_release(&header);
+       if (commit) {
+               arg1 = "commit";
+               arg2 = commit;
        } else {
-               struct object_id head;
-               struct commit *head_commit;
-               const char *head_message, *body;
+               arg1 = "message";
+       }
+       if (run_commit_hook(0, r->index_file, "prepare-commit-msg", name,
+                           arg1, arg2, NULL))
+               ret = error(_("'prepare-commit-msg' hook failed"));
 
-               if (get_oid("HEAD", &head))
-                       return error(_("need a HEAD to fixup"));
-               if (!(head_commit = lookup_commit_reference(&head)))
-                       return error(_("could not read HEAD"));
-               if (!(head_message = get_commit_buffer(head_commit, NULL)))
-                       return error(_("could not read HEAD's commit message"));
+       return ret;
+}
 
-               find_commit_subject(head_message, &body);
-               if (write_message(body, strlen(body),
-                                 rebase_path_fixup_msg(), 0)) {
-                       unuse_commit_buffer(head_commit, head_message);
-                       return error(_("cannot write '%s'"),
+static const char implicit_ident_advice_noconfig[] =
+N_("Your name and email address were configured automatically based\n"
+"on your username and hostname. Please check that they are accurate.\n"
+"You can suppress this message by setting them explicitly. Run the\n"
+"following command and follow the instructions in your editor to edit\n"
+"your configuration file:\n"
+"\n"
+"    git config --global --edit\n"
+"\n"
+"After doing this, you may fix the identity used for this commit with:\n"
+"\n"
+"    git commit --amend --reset-author\n");
+
+static const char implicit_ident_advice_config[] =
+N_("Your name and email address were configured automatically based\n"
+"on your username and hostname. Please check that they are accurate.\n"
+"You can suppress this message by setting them explicitly:\n"
+"\n"
+"    git config --global user.name \"Your Name\"\n"
+"    git config --global user.email you@example.com\n"
+"\n"
+"After doing this, you may fix the identity used for this commit with:\n"
+"\n"
+"    git commit --amend --reset-author\n");
+
+static const char *implicit_ident_advice(void)
+{
+       char *user_config = expand_user_path("~/.gitconfig", 0);
+       char *xdg_config = xdg_config_home("config");
+       int config_exists = file_exists(user_config) || file_exists(xdg_config);
+
+       free(user_config);
+       free(xdg_config);
+
+       if (config_exists)
+               return _(implicit_ident_advice_config);
+       else
+               return _(implicit_ident_advice_noconfig);
+
+}
+
+void print_commit_summary(struct repository *r,
+                         const char *prefix,
+                         const struct object_id *oid,
+                         unsigned int flags)
+{
+       struct rev_info rev;
+       struct commit *commit;
+       struct strbuf format = STRBUF_INIT;
+       const char *head;
+       struct pretty_print_context pctx = {0};
+       struct strbuf author_ident = STRBUF_INIT;
+       struct strbuf committer_ident = STRBUF_INIT;
+
+       commit = lookup_commit(r, oid);
+       if (!commit)
+               die(_("couldn't look up newly created commit"));
+       if (parse_commit(commit))
+               die(_("could not parse newly created commit"));
+
+       strbuf_addstr(&format, "format:%h] %s");
+
+       format_commit_message(commit, "%an <%ae>", &author_ident, &pctx);
+       format_commit_message(commit, "%cn <%ce>", &committer_ident, &pctx);
+       if (strbuf_cmp(&author_ident, &committer_ident)) {
+               strbuf_addstr(&format, "\n Author: ");
+               strbuf_addbuf_percentquote(&format, &author_ident);
+       }
+       if (flags & SUMMARY_SHOW_AUTHOR_DATE) {
+               struct strbuf date = STRBUF_INIT;
+
+               format_commit_message(commit, "%ad", &date, &pctx);
+               strbuf_addstr(&format, "\n Date: ");
+               strbuf_addbuf_percentquote(&format, &date);
+               strbuf_release(&date);
+       }
+       if (!committer_ident_sufficiently_given()) {
+               strbuf_addstr(&format, "\n Committer: ");
+               strbuf_addbuf_percentquote(&format, &committer_ident);
+               if (advice_implicit_identity) {
+                       strbuf_addch(&format, '\n');
+                       strbuf_addstr(&format, implicit_ident_advice());
+               }
+       }
+       strbuf_release(&author_ident);
+       strbuf_release(&committer_ident);
+
+       repo_init_revisions(r, &rev, prefix);
+       setup_revisions(0, NULL, &rev, NULL);
+
+       rev.diff = 1;
+       rev.diffopt.output_format =
+               DIFF_FORMAT_SHORTSTAT | DIFF_FORMAT_SUMMARY;
+
+       rev.verbose_header = 1;
+       rev.show_root_diff = 1;
+       get_commit_format(format.buf, &rev);
+       rev.always_show_header = 0;
+       rev.diffopt.detect_rename = DIFF_DETECT_RENAME;
+       rev.diffopt.break_opt = 0;
+       diff_setup_done(&rev.diffopt);
+
+       head = resolve_ref_unsafe("HEAD", 0, NULL, NULL);
+       if (!head)
+               die_errno(_("unable to resolve HEAD after creating commit"));
+       if (!strcmp(head, "HEAD"))
+               head = _("detached HEAD");
+       else
+               skip_prefix(head, "refs/heads/", &head);
+       printf("[%s%s ", head, (flags & SUMMARY_INITIAL_COMMIT) ?
+                                               _(" (root-commit)") : "");
+
+       if (!log_tree_commit(&rev, commit)) {
+               rev.always_show_header = 1;
+               rev.use_terminator = 1;
+               log_tree_commit(&rev, commit);
+       }
+
+       strbuf_release(&format);
+}
+
+static int parse_head(struct repository *r, struct commit **head)
+{
+       struct commit *current_head;
+       struct object_id oid;
+
+       if (get_oid("HEAD", &oid)) {
+               current_head = NULL;
+       } else {
+               current_head = lookup_commit_reference(r, &oid);
+               if (!current_head)
+                       return error(_("could not parse HEAD"));
+               if (!oideq(&oid, &current_head->object.oid)) {
+                       warning(_("HEAD %s is not a commit!"),
+                               oid_to_hex(&oid));
+               }
+               if (parse_commit(current_head))
+                       return error(_("could not parse HEAD commit"));
+       }
+       *head = current_head;
+
+       return 0;
+}
+
+/*
+ * Try to commit without forking 'git commit'. In some cases we need
+ * to run 'git commit' to display an error message
+ *
+ * Returns:
+ *  -1 - error unable to commit
+ *   0 - success
+ *   1 - run 'git commit'
+ */
+static int try_to_commit(struct repository *r,
+                        struct strbuf *msg, const char *author,
+                        struct replay_opts *opts, unsigned int flags,
+                        struct object_id *oid)
+{
+       struct object_id tree;
+       struct commit *current_head = NULL;
+       struct commit_list *parents = NULL;
+       struct commit_extra_header *extra = NULL;
+       struct strbuf err = STRBUF_INIT;
+       struct strbuf commit_msg = STRBUF_INIT;
+       char *amend_author = NULL;
+       const char *hook_commit = NULL;
+       enum commit_msg_cleanup_mode cleanup;
+       int res = 0;
+
+       if (parse_head(r, &current_head))
+               return -1;
+
+       if (flags & AMEND_MSG) {
+               const char *exclude_gpgsig[] = { "gpgsig", NULL };
+               const char *out_enc = get_commit_output_encoding();
+               const char *message = logmsg_reencode(current_head, NULL,
+                                                     out_enc);
+
+               if (!msg) {
+                       const char *orig_message = NULL;
+
+                       find_commit_subject(message, &orig_message);
+                       msg = &commit_msg;
+                       strbuf_addstr(msg, orig_message);
+                       hook_commit = "HEAD";
+               }
+               author = amend_author = get_author(message);
+               unuse_commit_buffer(current_head, message);
+               if (!author) {
+                       res = error(_("unable to parse commit author"));
+                       goto out;
+               }
+               parents = copy_commit_list(current_head->parents);
+               extra = read_commit_extra_headers(current_head, exclude_gpgsig);
+       } else if (current_head &&
+                  (!(flags & CREATE_ROOT_COMMIT) || (flags & AMEND_MSG))) {
+               commit_list_insert(current_head, &parents);
+       }
+
+       if (write_index_as_tree(&tree, r->index, r->index_file, 0, NULL)) {
+               res = error(_("git write-tree failed to write a tree"));
+               goto out;
+       }
+
+       if (!(flags & ALLOW_EMPTY)) {
+               struct commit *first_parent = current_head;
+
+               if (flags & AMEND_MSG) {
+                       if (current_head->parents) {
+                               first_parent = current_head->parents->item;
+                               if (repo_parse_commit(r, first_parent)) {
+                                       res = error(_("could not parse HEAD commit"));
+                                       goto out;
+                               }
+                       } else {
+                               first_parent = NULL;
+                       }
+               }
+               if (oideq(first_parent
+                         ? get_commit_tree_oid(first_parent)
+                         : the_hash_algo->empty_tree,
+                         &tree)) {
+                       res = 1; /* run 'git commit' to display error message */
+                       goto out;
+               }
+       }
+
+       if (find_hook("prepare-commit-msg")) {
+               res = run_prepare_commit_msg_hook(r, msg, hook_commit);
+               if (res)
+                       goto out;
+               if (strbuf_read_file(&commit_msg, git_path_commit_editmsg(),
+                                    2048) < 0) {
+                       res = error_errno(_("unable to read commit message "
+                                             "from '%s'"),
+                                           git_path_commit_editmsg());
+                       goto out;
+               }
+               msg = &commit_msg;
+       }
+
+       if (flags & CLEANUP_MSG)
+               cleanup = COMMIT_MSG_CLEANUP_ALL;
+       else if ((opts->signoff || opts->record_origin) &&
+                !opts->explicit_cleanup)
+               cleanup = COMMIT_MSG_CLEANUP_SPACE;
+       else
+               cleanup = opts->default_msg_cleanup;
+
+       if (cleanup != COMMIT_MSG_CLEANUP_NONE)
+               strbuf_stripspace(msg, cleanup == COMMIT_MSG_CLEANUP_ALL);
+       if ((flags & EDIT_MSG) && message_is_empty(msg, cleanup)) {
+               res = 1; /* run 'git commit' to display error message */
+               goto out;
+       }
+
+       reset_ident_date();
+
+       if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
+                                oid, author, opts->gpg_sign, extra)) {
+               res = error(_("failed to write commit object"));
+               goto out;
+       }
+
+       if (update_head_with_reflog(current_head, oid,
+                                   getenv("GIT_REFLOG_ACTION"), msg, &err)) {
+               res = error("%s", err.buf);
+               goto out;
+       }
+
+       run_commit_hook(0, r->index_file, "post-commit", NULL);
+       if (flags & AMEND_MSG)
+               commit_post_rewrite(r, current_head, oid);
+
+out:
+       free_commit_extra_headers(extra);
+       strbuf_release(&err);
+       strbuf_release(&commit_msg);
+       free(amend_author);
+
+       return res;
+}
+
+static int do_commit(struct repository *r,
+                    const char *msg_file, const char *author,
+                    struct replay_opts *opts, unsigned int flags)
+{
+       int res = 1;
+
+       if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG)) {
+               struct object_id oid;
+               struct strbuf sb = STRBUF_INIT;
+
+               if (msg_file && strbuf_read_file(&sb, msg_file, 2048) < 0)
+                       return error_errno(_("unable to read commit message "
+                                            "from '%s'"),
+                                          msg_file);
+
+               res = try_to_commit(r, msg_file ? &sb : NULL,
+                                   author, opts, flags, &oid);
+               strbuf_release(&sb);
+               if (!res) {
+                       unlink(git_path_cherry_pick_head(r));
+                       unlink(git_path_merge_msg(r));
+                       if (!is_rebase_i(opts))
+                               print_commit_summary(r, NULL, &oid,
+                                               SUMMARY_SHOW_AUTHOR_DATE);
+                       return res;
+               }
+       }
+       if (res == 1)
+               return run_git_commit(r, msg_file, opts, flags);
+
+       return res;
+}
+
+static int is_original_commit_empty(struct commit *commit)
+{
+       const struct object_id *ptree_oid;
+
+       if (parse_commit(commit))
+               return error(_("could not parse commit %s"),
+                            oid_to_hex(&commit->object.oid));
+       if (commit->parents) {
+               struct commit *parent = commit->parents->item;
+               if (parse_commit(parent))
+                       return error(_("could not parse parent commit %s"),
+                               oid_to_hex(&parent->object.oid));
+               ptree_oid = get_commit_tree_oid(parent);
+       } else {
+               ptree_oid = the_hash_algo->empty_tree; /* commit is root */
+       }
+
+       return oideq(ptree_oid, get_commit_tree_oid(commit));
+}
+
+/*
+ * Do we run "git commit" with "--allow-empty"?
+ */
+static int allow_empty(struct repository *r,
+                      struct replay_opts *opts,
+                      struct commit *commit)
+{
+       int index_unchanged, empty_commit;
+
+       /*
+        * Three cases:
+        *
+        * (1) we do not allow empty at all and error out.
+        *
+        * (2) we allow ones that were initially empty, but
+        * forbid the ones that become empty;
+        *
+        * (3) we allow both.
+        */
+       if (!opts->allow_empty)
+               return 0; /* let "git commit" barf as necessary */
+
+       index_unchanged = is_index_unchanged(r);
+       if (index_unchanged < 0)
+               return index_unchanged;
+       if (!index_unchanged)
+               return 0; /* we do not have to say --allow-empty */
+
+       if (opts->keep_redundant_commits)
+               return 1;
+
+       empty_commit = is_original_commit_empty(commit);
+       if (empty_commit < 0)
+               return empty_commit;
+       if (!empty_commit)
+               return 0;
+       else
+               return 1;
+}
+
+static struct {
+       char c;
+       const char *str;
+} todo_command_info[] = {
+       { 'p', "pick" },
+       { 0,   "revert" },
+       { 'e', "edit" },
+       { 'r', "reword" },
+       { 'f', "fixup" },
+       { 's', "squash" },
+       { 'x', "exec" },
+       { 'b', "break" },
+       { 'l', "label" },
+       { 't', "reset" },
+       { 'm', "merge" },
+       { 0,   "noop" },
+       { 'd', "drop" },
+       { 0,   NULL }
+};
+
+static const char *command_to_string(const enum todo_command command)
+{
+       if (command < TODO_COMMENT)
+               return todo_command_info[command].str;
+       die(_("unknown command: %d"), command);
+}
+
+static char command_to_char(const enum todo_command command)
+{
+       if (command < TODO_COMMENT && todo_command_info[command].c)
+               return todo_command_info[command].c;
+       return comment_line_char;
+}
+
+static int is_noop(const enum todo_command command)
+{
+       return TODO_NOOP <= command;
+}
+
+static int is_fixup(enum todo_command command)
+{
+       return command == TODO_FIXUP || command == TODO_SQUASH;
+}
+
+/* Does this command create a (non-merge) commit? */
+static int is_pick_or_similar(enum todo_command command)
+{
+       switch (command) {
+       case TODO_PICK:
+       case TODO_REVERT:
+       case TODO_EDIT:
+       case TODO_REWORD:
+       case TODO_FIXUP:
+       case TODO_SQUASH:
+               return 1;
+       default:
+               return 0;
+       }
+}
+
+static int update_squash_messages(struct repository *r,
+                                 enum todo_command command,
+                                 struct commit *commit,
+                                 struct replay_opts *opts)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int res;
+       const char *message, *body;
+       const char *encoding = get_commit_output_encoding();
+
+       if (opts->current_fixup_count > 0) {
+               struct strbuf header = STRBUF_INIT;
+               char *eol;
+
+               if (strbuf_read_file(&buf, rebase_path_squash_msg(), 9) <= 0)
+                       return error(_("could not read '%s'"),
+                               rebase_path_squash_msg());
+
+               eol = buf.buf[0] != comment_line_char ?
+                       buf.buf : strchrnul(buf.buf, '\n');
+
+               strbuf_addf(&header, "%c ", comment_line_char);
+               strbuf_addf(&header, _("This is a combination of %d commits."),
+                           opts->current_fixup_count + 2);
+               strbuf_splice(&buf, 0, eol - buf.buf, header.buf, header.len);
+               strbuf_release(&header);
+       } else {
+               struct object_id head;
+               struct commit *head_commit;
+               const char *head_message, *body;
+
+               if (get_oid("HEAD", &head))
+                       return error(_("need a HEAD to fixup"));
+               if (!(head_commit = lookup_commit_reference(r, &head)))
+                       return error(_("could not read HEAD"));
+               if (!(head_message = logmsg_reencode(head_commit, NULL, encoding)))
+                       return error(_("could not read HEAD's commit message"));
+
+               find_commit_subject(head_message, &body);
+               if (write_message(body, strlen(body),
+                                 rebase_path_fixup_msg(), 0)) {
+                       unuse_commit_buffer(head_commit, head_message);
+                       return error(_("cannot write '%s'"),
                                     rebase_path_fixup_msg());
                }
 
-               count = 2;
                strbuf_addf(&buf, "%c ", comment_line_char);
-               strbuf_addf(&buf, _("This is a combination of %d commits."),
-                           count);
+               strbuf_addf(&buf, _("This is a combination of %d commits."), 2);
                strbuf_addf(&buf, "\n%c ", comment_line_char);
                strbuf_addstr(&buf, _("This is the 1st commit message:"));
                strbuf_addstr(&buf, "\n\n");
@@ -870,7 +1638,7 @@ static int update_squash_messages(enum todo_command command,
                unuse_commit_buffer(head_commit, head_message);
        }
 
-       if (!(message = get_commit_buffer(commit, NULL)))
+       if (!(message = logmsg_reencode(commit, NULL, encoding)))
                return error(_("could not read commit message of %s"),
                             oid_to_hex(&commit->object.oid));
        find_commit_subject(message, &body);
@@ -878,13 +1646,14 @@ static int update_squash_messages(enum todo_command command,
        if (command == TODO_SQUASH) {
                unlink(rebase_path_fixup_msg());
                strbuf_addf(&buf, "\n%c ", comment_line_char);
-               strbuf_addf(&buf, _("This is the commit message #%d:"), count);
+               strbuf_addf(&buf, _("This is the commit message #%d:"),
+                           ++opts->current_fixup_count + 1);
                strbuf_addstr(&buf, "\n\n");
                strbuf_addstr(&buf, body);
        } else if (command == TODO_FIXUP) {
                strbuf_addf(&buf, "\n%c ", comment_line_char);
                strbuf_addf(&buf, _("The commit message #%d will be skipped:"),
-                           count);
+                           ++opts->current_fixup_count + 1);
                strbuf_addstr(&buf, "\n\n");
                strbuf_add_commented_lines(&buf, body, strlen(body));
        } else
@@ -893,10 +1662,22 @@ static int update_squash_messages(enum todo_command command,
 
        res = write_message(buf.buf, buf.len, rebase_path_squash_msg(), 0);
        strbuf_release(&buf);
+
+       if (!res) {
+               strbuf_addf(&opts->current_fixups, "%s%s %s",
+                           opts->current_fixups.len ? "\n" : "",
+                           command_to_string(command),
+                           oid_to_hex(&commit->object.oid));
+               res = write_message(opts->current_fixups.buf,
+                                   opts->current_fixups.len,
+                                   rebase_path_current_fixups(), 0);
+       }
+
        return res;
 }
 
-static void flush_rewritten_pending(void) {
+static void flush_rewritten_pending(void)
+{
        struct strbuf buf = STRBUF_INIT;
        struct object_id newoid;
        FILE *out;
@@ -921,7 +1702,8 @@ static void flush_rewritten_pending(void) {
 }
 
 static void record_in_rewritten(struct object_id *oid,
-               enum todo_command next_command) {
+               enum todo_command next_command)
+{
        FILE *out = fopen_or_warn(rebase_path_rewritten_pending(), "a");
 
        if (!out)
@@ -934,17 +1716,21 @@ static void record_in_rewritten(struct object_id *oid,
                flush_rewritten_pending();
 }
 
-static int do_pick_commit(enum todo_command command, struct commit *commit,
-               struct replay_opts *opts, int final_fixup)
+static int do_pick_commit(struct repository *r,
+                         enum todo_command command,
+                         struct commit *commit,
+                         struct replay_opts *opts,
+                         int final_fixup, int *check_todo)
 {
        unsigned int flags = opts->edit ? EDIT_MSG : 0;
-       const char *msg_file = opts->edit ? NULL : git_path_merge_msg();
+       const char *msg_file = opts->edit ? NULL : git_path_merge_msg(r);
        struct object_id head;
        struct commit *base, *next, *parent;
        const char *base_label, *next_label;
+       char *author = NULL;
        struct commit_message msg = { NULL, NULL, NULL, NULL };
        struct strbuf msgbuf = STRBUF_INIT;
-       int res, unborn = 0, allow;
+       int res, unborn = 0, reword = 0, allow;
 
        if (opts->no_commit) {
                /*
@@ -953,16 +1739,24 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                 * that represents the "current" state for merge-recursive
                 * to work on.
                 */
-               if (write_cache_as_tree(head.hash, 0, NULL))
+               if (write_index_as_tree(&head, r->index, r->index_file, 0, NULL))
                        return error(_("your index file is unmerged."));
        } else {
                unborn = get_oid("HEAD", &head);
-               if (unborn)
-                       oidcpy(&head, &empty_tree_oid);
-               if (index_differs_from(unborn ? EMPTY_TREE_SHA1_HEX : "HEAD", 0, 0))
-                       return error_dirty_index(opts);
+               /* Do we want to generate a root commit? */
+               if (is_pick_or_similar(command) && opts->have_squash_onto &&
+                   oideq(&head, &opts->squash_onto)) {
+                       if (is_fixup(command))
+                               return error(_("cannot fixup root commit"));
+                       flags |= CREATE_ROOT_COMMIT;
+                       unborn = 1;
+               } else if (unborn)
+                       oidcpy(&head, the_hash_algo->empty_tree);
+               if (index_differs_from(r, unborn ? empty_tree_oid_hex() : "HEAD",
+                                      NULL, 0))
+                       return error_dirty_index(r, opts);
        }
-       discard_cache();
+       discard_index(r->index);
 
        if (!commit->parents)
                parent = NULL;
@@ -983,9 +1777,13 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        return error(_("commit %s does not have parent %d"),
                                oid_to_hex(&commit->object.oid), opts->mainline);
                parent = p->item;
-       } else if (0 < opts->mainline)
-               return error(_("mainline was specified but commit %s is not a merge."),
-                       oid_to_hex(&commit->object.oid));
+       } else if (1 < opts->mainline)
+               /*
+                *  Non-first parent explicitly specified as mainline for
+                *  non-merge commit
+                */
+               return error(_("commit %s does not have parent %d"),
+                            oid_to_hex(&commit->object.oid), opts->mainline);
        else
                parent = commit->parents->item;
 
@@ -994,17 +1792,15 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        oid_to_hex(&commit->object.oid));
 
        if (opts->allow_ff && !is_fixup(command) &&
-           ((parent && !oidcmp(&parent->object.oid, &head)) ||
+           ((parent && oideq(&parent->object.oid, &head)) ||
             (!parent && unborn))) {
                if (is_rebase_i(opts))
                        write_author_script(msg.message);
-               res = fast_forward_to(&commit->object.oid, &head, unborn,
+               res = fast_forward_to(r, &commit->object.oid, &head, unborn,
                        opts);
                if (res || command != TODO_REWORD)
                        goto leave;
-               flags |= EDIT_MSG | AMEND_MSG;
-               if (command == TODO_REWORD)
-                       flags |= VERIFY_MSG;
+               reword = 1;
                msg_file = NULL;
                goto fast_forward_edit;
        }
@@ -1057,12 +1853,14 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        strbuf_addstr(&msgbuf, oid_to_hex(&commit->object.oid));
                        strbuf_addstr(&msgbuf, ")\n");
                }
+               if (!is_fixup(command))
+                       author = get_author(msg.message);
        }
 
        if (command == TODO_REWORD)
-               flags |= EDIT_MSG | VERIFY_MSG;
+               reword = 1;
        else if (is_fixup(command)) {
-               if (update_squash_messages(command, commit, opts))
+               if (update_squash_messages(r, command, commit, opts))
                        return -1;
                flags |= AMEND_MSG;
                if (!final_fixup)
@@ -1071,36 +1869,40 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        flags |= CLEANUP_MSG;
                        msg_file = rebase_path_fixup_msg();
                } else {
-                       const char *dest = git_path_squash_msg();
+                       const char *dest = git_path_squash_msg(r);
                        unlink(dest);
                        if (copy_file(dest, rebase_path_squash_msg(), 0666))
                                return error(_("could not rename '%s' to '%s'"),
                                             rebase_path_squash_msg(), dest);
-                       unlink(git_path_merge_msg());
+                       unlink(git_path_merge_msg(r));
                        msg_file = dest;
                        flags |= EDIT_MSG;
                }
        }
 
+       if (opts->signoff && !is_fixup(command))
+               append_signoff(&msgbuf, 0, 0);
+
        if (is_rebase_i(opts) && write_author_script(msg.message) < 0)
                res = -1;
        else if (!opts->strategy || !strcmp(opts->strategy, "recursive") || command == TODO_REVERT) {
-               res = do_recursive_merge(base, next, base_label, next_label,
+               res = do_recursive_merge(r, base, next, base_label, next_label,
                                         &head, &msgbuf, opts);
                if (res < 0)
-                       return res;
+                       goto leave;
+
                res |= write_message(msgbuf.buf, msgbuf.len,
-                                    git_path_merge_msg(), 0);
+                                    git_path_merge_msg(r), 0);
        } else {
                struct commit_list *common = NULL;
                struct commit_list *remotes = NULL;
 
                res = write_message(msgbuf.buf, msgbuf.len,
-                                   git_path_merge_msg(), 0);
+                                   git_path_merge_msg(r), 0);
 
                commit_list_insert(base, &common);
                commit_list_insert(next, &remotes);
-               res |= try_merge_command(opts->strategy,
+               res |= try_merge_command(r, opts->strategy,
                                         opts->xopts_nr, (const char **)opts->xopts,
                                        common, oid_to_hex(&head), remotes);
                free_commit_list(common);
@@ -1115,12 +1917,12 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
         * write it at all.
         */
        if (command == TODO_PICK && !opts->no_commit && (res == 0 || res == 1) &&
-           update_ref(NULL, "CHERRY_PICK_HEAD", commit->object.oid.hash, NULL,
-                      REF_NODEREF, UPDATE_REFS_MSG_ON_ERR))
+           update_ref(NULL, "CHERRY_PICK_HEAD", &commit->object.oid, NULL,
+                      REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR))
                res = -1;
        if (command == TODO_REVERT && ((opts->no_commit && res == 0) || res == 1) &&
-           update_ref(NULL, "REVERT_HEAD", commit->object.oid.hash, NULL,
-                      REF_NODEREF, UPDATE_REFS_MSG_ON_ERR))
+           update_ref(NULL, "REVERT_HEAD", &commit->object.oid, NULL,
+                      REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR))
                res = -1;
 
        if (res) {
@@ -1128,28 +1930,44 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                      ? _("could not revert %s... %s")
                      : _("could not apply %s... %s"),
                      short_commit_name(commit), msg.subject);
-               print_advice(res == 1, opts);
-               rerere(opts->allow_rerere_auto);
+               print_advice(r, res == 1, opts);
+               repo_rerere(r, opts->allow_rerere_auto);
                goto leave;
        }
 
-       allow = allow_empty(opts, commit);
+       allow = allow_empty(r, opts, commit);
        if (allow < 0) {
                res = allow;
                goto leave;
        } else if (allow)
                flags |= ALLOW_EMPTY;
-       if (!opts->no_commit)
+       if (!opts->no_commit) {
+               if (author || command == TODO_REVERT || (flags & AMEND_MSG))
+                       res = do_commit(r, msg_file, author, opts, flags);
+               else
+                       res = error(_("unable to parse commit author"));
+               *check_todo = !!(flags & EDIT_MSG);
+               if (!res && reword) {
 fast_forward_edit:
-               res = run_git_commit(msg_file, opts, flags);
+                       res = run_git_commit(r, NULL, opts, EDIT_MSG |
+                                            VERIFY_MSG | AMEND_MSG |
+                                            (flags & ALLOW_EMPTY));
+                       *check_todo = 1;
+               }
+       }
+
 
        if (!res && final_fixup) {
                unlink(rebase_path_fixup_msg());
                unlink(rebase_path_squash_msg());
+               unlink(rebase_path_current_fixups());
+               strbuf_reset(&opts->current_fixups);
+               opts->current_fixup_count = 0;
        }
 
 leave:
        free_message(commit, &msg);
+       free(author);
        update_abort_safety_file();
 
        return res;
@@ -1167,51 +1985,35 @@ static int prepare_revs(struct replay_opts *opts)
        if (prepare_revision_walk(opts->revs))
                return error(_("revision walk setup failed"));
 
-       if (!opts->revs->commits)
-               return error(_("empty commit set passed"));
        return 0;
 }
 
-static int read_and_refresh_cache(struct replay_opts *opts)
+static int read_and_refresh_cache(struct repository *r,
+                                 struct replay_opts *opts)
 {
-       static struct lock_file index_lock;
-       int index_fd = hold_locked_index(&index_lock, 0);
-       if (read_index_preload(&the_index, NULL) < 0) {
+       struct lock_file index_lock = LOCK_INIT;
+       int index_fd = repo_hold_locked_index(r, &index_lock, 0);
+       if (repo_read_index(r) < 0) {
                rollback_lock_file(&index_lock);
                return error(_("git %s: failed to read the index"),
                        _(action_name(opts)));
        }
-       refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
-       if (the_index.cache_changed && index_fd >= 0) {
-               if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK)) {
-                       rollback_lock_file(&index_lock);
+       refresh_index(r->index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
+       if (index_fd >= 0) {
+               if (write_locked_index(r->index, &index_lock,
+                                      COMMIT_LOCK | SKIP_IF_UNCHANGED)) {
                        return error(_("git %s: failed to refresh the index"),
                                _(action_name(opts)));
                }
        }
-       rollback_lock_file(&index_lock);
        return 0;
 }
 
-struct todo_item {
-       enum todo_command command;
-       struct commit *commit;
-       const char *arg;
-       int arg_len;
-       size_t offset_in_buf;
-};
-
-struct todo_list {
-       struct strbuf buf;
-       struct todo_item *items;
-       int nr, alloc, current;
-       int done_nr, total_nr;
-       struct stat_data stat;
+enum todo_item_flags {
+       TODO_EDIT_MERGE_MSG = 1
 };
 
-#define TODO_LIST_INIT { STRBUF_INIT }
-
-static void todo_list_release(struct todo_list *todo_list)
+void todo_list_release(struct todo_list *todo_list)
 {
        strbuf_release(&todo_list->buf);
        FREE_AND_NULL(todo_list->items);
@@ -1221,79 +2023,152 @@ static void todo_list_release(struct todo_list *todo_list)
 static struct todo_item *append_new_todo(struct todo_list *todo_list)
 {
        ALLOC_GROW(todo_list->items, todo_list->nr + 1, todo_list->alloc);
+       todo_list->total_nr++;
        return todo_list->items + todo_list->nr++;
 }
 
-static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
+const char *todo_item_get_arg(struct todo_list *todo_list,
+                             struct todo_item *item)
+{
+       return todo_list->buf.buf + item->arg_offset;
+}
+
+static int is_command(enum todo_command command, const char **bol)
+{
+       const char *str = todo_command_info[command].str;
+       const char nick = todo_command_info[command].c;
+       const char *p = *bol + 1;
+
+       return skip_prefix(*bol, str, bol) ||
+               ((nick && **bol == nick) &&
+                (*p == ' ' || *p == '\t' || *p == '\n' || *p == '\r' || !*p) &&
+                (*bol = p));
+}
+
+static int parse_insn_line(struct repository *r, struct todo_item *item,
+                          const char *buf, const char *bol, char *eol)
 {
        struct object_id commit_oid;
        char *end_of_object_name;
        int i, saved, status, padding;
 
+       item->flags = 0;
+
        /* left-trim */
        bol += strspn(bol, " \t");
 
        if (bol == eol || *bol == '\r' || *bol == comment_line_char) {
                item->command = TODO_COMMENT;
                item->commit = NULL;
-               item->arg = bol;
+               item->arg_offset = bol - buf;
                item->arg_len = eol - bol;
                return 0;
        }
 
        for (i = 0; i < TODO_COMMENT; i++)
-               if (skip_prefix(bol, todo_command_info[i].str, &bol)) {
-                       item->command = i;
-                       break;
-               } else if (bol[1] == ' ' && *bol == todo_command_info[i].c) {
-                       bol++;
+               if (is_command(i, &bol)) {
                        item->command = i;
                        break;
                }
        if (i >= TODO_COMMENT)
                return -1;
 
-       if (item->command == TODO_NOOP) {
+       /* Eat up extra spaces/ tabs before object name */
+       padding = strspn(bol, " \t");
+       bol += padding;
+
+       if (item->command == TODO_NOOP || item->command == TODO_BREAK) {
+               if (bol != eol)
+                       return error(_("%s does not accept arguments: '%s'"),
+                                    command_to_string(item->command), bol);
                item->commit = NULL;
-               item->arg = bol;
+               item->arg_offset = bol - buf;
                item->arg_len = eol - bol;
                return 0;
        }
 
-       /* Eat up extra spaces/ tabs before object name */
-       padding = strspn(bol, " \t");
        if (!padding)
-               return -1;
-       bol += padding;
+               return error(_("missing arguments for %s"),
+                            command_to_string(item->command));
 
-       if (item->command == TODO_EXEC) {
-               item->arg = bol;
+       if (item->command == TODO_EXEC || item->command == TODO_LABEL ||
+           item->command == TODO_RESET) {
+               item->commit = NULL;
+               item->arg_offset = bol - buf;
                item->arg_len = (int)(eol - bol);
                return 0;
        }
 
+       if (item->command == TODO_MERGE) {
+               if (skip_prefix(bol, "-C", &bol))
+                       bol += strspn(bol, " \t");
+               else if (skip_prefix(bol, "-c", &bol)) {
+                       bol += strspn(bol, " \t");
+                       item->flags |= TODO_EDIT_MERGE_MSG;
+               } else {
+                       item->flags |= TODO_EDIT_MERGE_MSG;
+                       item->commit = NULL;
+                       item->arg_offset = bol - buf;
+                       item->arg_len = (int)(eol - bol);
+                       return 0;
+               }
+       }
+
        end_of_object_name = (char *) bol + strcspn(bol, " \t\n");
        saved = *end_of_object_name;
        *end_of_object_name = '\0';
        status = get_oid(bol, &commit_oid);
+       if (status < 0)
+               error(_("could not parse '%s'"), bol); /* return later */
        *end_of_object_name = saved;
 
-       item->arg = end_of_object_name + strspn(end_of_object_name, " \t");
-       item->arg_len = (int)(eol - item->arg);
+       bol = end_of_object_name + strspn(end_of_object_name, " \t");
+       item->arg_offset = bol - buf;
+       item->arg_len = (int)(eol - bol);
 
        if (status < 0)
-               return -1;
+               return status;
+
+       item->commit = lookup_commit_reference(r, &commit_oid);
+       return item->commit ? 0 : -1;
+}
+
+int sequencer_get_last_command(struct repository *r, enum replay_action *action)
+{
+       const char *todo_file, *bol;
+       struct strbuf buf = STRBUF_INIT;
+       int ret = 0;
 
-       item->commit = lookup_commit_reference(&commit_oid);
-       return !item->commit;
+       todo_file = git_path_todo_file();
+       if (strbuf_read_file(&buf, todo_file, 0) < 0) {
+               if (errno == ENOENT || errno == ENOTDIR)
+                       return -1;
+               else
+                       return error_errno("unable to open '%s'", todo_file);
+       }
+       bol = buf.buf + strspn(buf.buf, " \t\r\n");
+       if (is_command(TODO_PICK, &bol) && (*bol == ' ' || *bol == '\t'))
+               *action = REPLAY_PICK;
+       else if (is_command(TODO_REVERT, &bol) &&
+                (*bol == ' ' || *bol == '\t'))
+               *action = REPLAY_REVERT;
+       else
+               ret = -1;
+
+       strbuf_release(&buf);
+
+       return ret;
 }
 
-static int parse_insn_buffer(char *buf, struct todo_list *todo_list)
+int todo_list_parse_insn_buffer(struct repository *r, char *buf,
+                               struct todo_list *todo_list)
 {
        struct todo_item *item;
        char *p = buf, *next_p;
        int i, res = 0, fixup_okay = file_exists(rebase_path_done());
 
+       todo_list->current = todo_list->nr = 0;
+
        for (i = 1; *p; i++, p = next_p) {
                char *eol = strchrnul(p, '\n');
 
@@ -1304,10 +2179,13 @@ static int parse_insn_buffer(char *buf, struct todo_list *todo_list)
 
                item = append_new_todo(todo_list);
                item->offset_in_buf = p - todo_list->buf.buf;
-               if (parse_insn_line(item, p, eol)) {
+               if (parse_insn_line(r, item, buf, p, eol)) {
                        res = error(_("invalid line %d: %.*s"),
                                i, (int)(eol - p), p);
-                       item->command = TODO_NOOP;
+                       item->command = TODO_COMMENT + 1;
+                       item->arg_offset = p - buf;
+                       item->arg_len = (int)(eol - p);
+                       item->commit = NULL;
                }
 
                if (fixup_okay)
@@ -1333,29 +2211,119 @@ static int count_commands(struct todo_list *todo_list)
        return count;
 }
 
-static int read_populate_todo(struct todo_list *todo_list,
-                       struct replay_opts *opts)
+static int get_item_line_offset(struct todo_list *todo_list, int index)
+{
+       return index < todo_list->nr ?
+               todo_list->items[index].offset_in_buf : todo_list->buf.len;
+}
+
+static const char *get_item_line(struct todo_list *todo_list, int index)
+{
+       return todo_list->buf.buf + get_item_line_offset(todo_list, index);
+}
+
+static int get_item_line_length(struct todo_list *todo_list, int index)
+{
+       return get_item_line_offset(todo_list, index + 1)
+               -  get_item_line_offset(todo_list, index);
+}
+
+static ssize_t strbuf_read_file_or_whine(struct strbuf *sb, const char *path)
+{
+       int fd;
+       ssize_t len;
+
+       fd = open(path, O_RDONLY);
+       if (fd < 0)
+               return error_errno(_("could not open '%s'"), path);
+       len = strbuf_read(sb, fd, 0);
+       close(fd);
+       if (len < 0)
+               return error(_("could not read '%s'."), path);
+       return len;
+}
+
+static int have_finished_the_last_pick(void)
+{
+       struct strbuf buf = STRBUF_INIT;
+       const char *eol;
+       const char *todo_path = git_path_todo_file();
+       int ret = 0;
+
+       if (strbuf_read_file(&buf, todo_path, 0) < 0) {
+               if (errno == ENOENT) {
+                       return 0;
+               } else {
+                       error_errno("unable to open '%s'", todo_path);
+                       return 0;
+               }
+       }
+       /* If there is only one line then we are done */
+       eol = strchr(buf.buf, '\n');
+       if (!eol || !eol[1])
+               ret = 1;
+
+       strbuf_release(&buf);
+
+       return ret;
+}
+
+void sequencer_post_commit_cleanup(struct repository *r, int verbose)
+{
+       struct replay_opts opts = REPLAY_OPTS_INIT;
+       int need_cleanup = 0;
+
+       if (file_exists(git_path_cherry_pick_head(r))) {
+               if (!unlink(git_path_cherry_pick_head(r)) && verbose)
+                       warning(_("cancelling a cherry picking in progress"));
+               opts.action = REPLAY_PICK;
+               need_cleanup = 1;
+       }
+
+       if (file_exists(git_path_revert_head(r))) {
+               if (!unlink(git_path_revert_head(r)) && verbose)
+                       warning(_("cancelling a revert in progress"));
+               opts.action = REPLAY_REVERT;
+               need_cleanup = 1;
+       }
+
+       if (!need_cleanup)
+               return;
+
+       if (!have_finished_the_last_pick())
+               return;
+
+       sequencer_remove_state(&opts);
+}
+
+static void todo_list_write_total_nr(struct todo_list *todo_list)
+{
+       FILE *f = fopen_or_warn(rebase_path_msgtotal(), "w");
+
+       if (f) {
+               fprintf(f, "%d\n", todo_list->total_nr);
+               fclose(f);
+       }
+}
+
+static int read_populate_todo(struct repository *r,
+                             struct todo_list *todo_list,
+                             struct replay_opts *opts)
 {
        struct stat st;
        const char *todo_file = get_todo_path(opts);
-       int fd, res;
+       int res;
 
        strbuf_reset(&todo_list->buf);
-       fd = open(todo_file, O_RDONLY);
-       if (fd < 0)
-               return error_errno(_("could not open '%s'"), todo_file);
-       if (strbuf_read(&todo_list->buf, fd, 0) < 0) {
-               close(fd);
-               return error(_("could not read '%s'."), todo_file);
-       }
-       close(fd);
+       if (strbuf_read_file_or_whine(&todo_list->buf, todo_file) < 0)
+               return -1;
 
        res = stat(todo_file, &st);
        if (res)
                return error(_("could not stat '%s'"), todo_file);
        fill_stat_data(&todo_list->stat, &st);
 
-       res = parse_insn_buffer(todo_list->buf.buf, todo_list);
+       res = todo_list_parse_insn_buffer(r, todo_list->buf.buf, todo_list);
        if (res) {
                if (is_rebase_i(opts))
                        return error(_("please fix this using "
@@ -1383,10 +2351,9 @@ static int read_populate_todo(struct todo_list *todo_list,
 
        if (is_rebase_i(opts)) {
                struct todo_list done = TODO_LIST_INIT;
-               FILE *f = fopen_or_warn(rebase_path_msgtotal(), "w");
 
                if (strbuf_read_file(&done.buf, rebase_path_done(), 0) > 0 &&
-                               !parse_insn_buffer(done.buf.buf, &done))
+                   !todo_list_parse_insn_buffer(r, done.buf.buf, &done))
                        todo_list->done_nr = count_commands(&done);
                else
                        todo_list->done_nr = 0;
@@ -1395,10 +2362,7 @@ static int read_populate_todo(struct todo_list *todo_list,
                        + count_commands(todo_list);
                todo_list_release(&done);
 
-               if (f) {
-                       fprintf(f, "%d\n", todo_list->total_nr);
-                       fclose(f);
-               }
+               todo_list_write_total_nr(todo_list);
        }
 
        return 0;
@@ -1425,6 +2389,15 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
                opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
        else if (!strcmp(key, "options.edit"))
                opts->edit = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.allow-empty"))
+               opts->allow_empty =
+                       git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.allow-empty-message"))
+               opts->allow_empty_message =
+                       git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.keep-redundant-commits"))
+               opts->keep_redundant_commits =
+                       git_config_bool_or_int(key, value, &error_flag);
        else if (!strcmp(key, "options.signoff"))
                opts->signoff = git_config_bool_or_int(key, value, &error_flag);
        else if (!strcmp(key, "options.record-origin"))
@@ -1444,7 +2417,10 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
                opts->allow_rerere_auto =
                        git_config_bool_or_int(key, value, &error_flag) ?
                                RERERE_AUTOUPDATE : RERERE_NOAUTOUPDATE;
-       else
+       else if (!strcmp(key, "options.default-msg-cleanup")) {
+               opts->explicit_cleanup = 1;
+               opts->default_msg_cleanup = get_cleanup_mode(value, 1);
+       } else
                return error(_("invalid key: %s"), key);
 
        if (!error_flag)
@@ -1453,18 +2429,16 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
        return 0;
 }
 
-static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
+void parse_strategy_opts(struct replay_opts *opts, char *raw_opts)
 {
        int i;
+       char *strategy_opts_string = raw_opts;
 
-       strbuf_reset(buf);
-       if (!read_oneliner(buf, rebase_path_strategy(), 0))
-               return;
-       opts->strategy = strbuf_detach(buf, NULL);
-       if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
-               return;
+       if (*strategy_opts_string == ' ')
+               strategy_opts_string++;
 
-       opts->xopts_nr = split_cmdline(buf->buf, (const char ***)&opts->xopts);
+       opts->xopts_nr = split_cmdline(strategy_opts_string,
+                                      (const char ***)&opts->xopts);
        for (i = 0; i < opts->xopts_nr; i++) {
                const char *arg = opts->xopts[i];
 
@@ -1473,6 +2447,18 @@ static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
        }
 }
 
+static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
+{
+       strbuf_reset(buf);
+       if (!read_oneliner(buf, rebase_path_strategy(), 0))
+               return;
+       opts->strategy = strbuf_detach(buf, NULL);
+       if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
+               return;
+
+       parse_strategy_opts(opts, buf->buf);
+}
+
 static int read_populate_opts(struct replay_opts *opts)
 {
        if (is_rebase_i(opts)) {
@@ -1499,9 +2485,36 @@ static int read_populate_opts(struct replay_opts *opts)
                if (file_exists(rebase_path_verbose()))
                        opts->verbose = 1;
 
+               if (file_exists(rebase_path_quiet()))
+                       opts->quiet = 1;
+
+               if (file_exists(rebase_path_signoff())) {
+                       opts->allow_ff = 0;
+                       opts->signoff = 1;
+               }
+
+               if (file_exists(rebase_path_reschedule_failed_exec()))
+                       opts->reschedule_failed_exec = 1;
+
                read_strategy_opts(opts, &buf);
                strbuf_release(&buf);
 
+               if (read_oneliner(&opts->current_fixups,
+                                 rebase_path_current_fixups(), 1)) {
+                       const char *p = opts->current_fixups.buf;
+                       opts->current_fixup_count = 1;
+                       while ((p = strchr(p, '\n'))) {
+                               opts->current_fixup_count++;
+                               p++;
+                       }
+               }
+
+               if (read_oneliner(&buf, rebase_path_squash_onto(), 0)) {
+                       if (get_oid_hex(buf.buf, &opts->squash_onto) < 0)
+                               return error(_("unusable squash-onto"));
+                       opts->have_squash_onto = 1;
+               }
+
                return 0;
        }
 
@@ -1519,26 +2532,78 @@ static int read_populate_opts(struct replay_opts *opts)
        return 0;
 }
 
+static void write_strategy_opts(struct replay_opts *opts)
+{
+       int i;
+       struct strbuf buf = STRBUF_INIT;
+
+       for (i = 0; i < opts->xopts_nr; ++i)
+               strbuf_addf(&buf, " --%s", opts->xopts[i]);
+
+       write_file(rebase_path_strategy_opts(), "%s\n", buf.buf);
+       strbuf_release(&buf);
+}
+
+int write_basic_state(struct replay_opts *opts, const char *head_name,
+                     struct commit *onto, const char *orig_head)
+{
+       const char *quiet = getenv("GIT_QUIET");
+
+       if (head_name)
+               write_file(rebase_path_head_name(), "%s\n", head_name);
+       if (onto)
+               write_file(rebase_path_onto(), "%s\n",
+                          oid_to_hex(&onto->object.oid));
+       if (orig_head)
+               write_file(rebase_path_orig_head(), "%s\n", orig_head);
+
+       if (quiet)
+               write_file(rebase_path_quiet(), "%s\n", quiet);
+       if (opts->verbose)
+               write_file(rebase_path_verbose(), "%s", "");
+       if (opts->strategy)
+               write_file(rebase_path_strategy(), "%s\n", opts->strategy);
+       if (opts->xopts_nr > 0)
+               write_strategy_opts(opts);
+
+       if (opts->allow_rerere_auto == RERERE_AUTOUPDATE)
+               write_file(rebase_path_allow_rerere_autoupdate(), "--rerere-autoupdate\n");
+       else if (opts->allow_rerere_auto == RERERE_NOAUTOUPDATE)
+               write_file(rebase_path_allow_rerere_autoupdate(), "--no-rerere-autoupdate\n");
+
+       if (opts->gpg_sign)
+               write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
+       if (opts->signoff)
+               write_file(rebase_path_signoff(), "--signoff\n");
+       if (opts->reschedule_failed_exec)
+               write_file(rebase_path_reschedule_failed_exec(), "%s", "");
+
+       return 0;
+}
+
 static int walk_revs_populate_todo(struct todo_list *todo_list,
                                struct replay_opts *opts)
 {
        enum todo_command command = opts->action == REPLAY_PICK ?
                TODO_PICK : TODO_REVERT;
        const char *command_string = todo_command_info[command].str;
+       const char *encoding;
        struct commit *commit;
 
        if (prepare_revs(opts))
                return -1;
 
+       encoding = get_log_output_encoding();
+
        while ((commit = get_revision(opts->revs))) {
                struct todo_item *item = append_new_todo(todo_list);
-               const char *commit_buffer = get_commit_buffer(commit, NULL);
+               const char *commit_buffer = logmsg_reencode(commit, NULL, encoding);
                const char *subject;
                int subject_len;
 
                item->command = command;
                item->commit = commit;
-               item->arg = NULL;
+               item->arg_offset = 0;
                item->arg_len = 0;
                item->offset_in_buf = todo_list->buf.len;
                subject_len = find_commit_subject(commit_buffer, &subject);
@@ -1546,45 +2611,71 @@ static int walk_revs_populate_todo(struct todo_list *todo_list,
                        short_commit_name(commit), subject_len, subject);
                unuse_commit_buffer(commit, commit_buffer);
        }
+
+       if (!todo_list->nr)
+               return error(_("empty commit set passed"));
+
        return 0;
 }
 
-static int create_seq_dir(void)
+static int create_seq_dir(struct repository *r)
 {
-       if (file_exists(git_path_seq_dir())) {
-               error(_("a cherry-pick or revert is already in progress"));
-               advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
+       enum replay_action action;
+       const char *in_progress_error = NULL;
+       const char *in_progress_advice = NULL;
+       unsigned int advise_skip = file_exists(git_path_revert_head(r)) ||
+                               file_exists(git_path_cherry_pick_head(r));
+
+       if (!sequencer_get_last_command(r, &action)) {
+               switch (action) {
+               case REPLAY_REVERT:
+                       in_progress_error = _("revert is already in progress");
+                       in_progress_advice =
+                       _("try \"git revert (--continue | %s--abort | --quit)\"");
+                       break;
+               case REPLAY_PICK:
+                       in_progress_error = _("cherry-pick is already in progress");
+                       in_progress_advice =
+                       _("try \"git cherry-pick (--continue | %s--abort | --quit)\"");
+                       break;
+               default:
+                       BUG("unexpected action in create_seq_dir");
+               }
+       }
+       if (in_progress_error) {
+               error("%s", in_progress_error);
+               if (advice_sequencer_in_use)
+                       advise(in_progress_advice,
+                               advise_skip ? "--skip | " : "");
                return -1;
-       } else if (mkdir(git_path_seq_dir(), 0777) < 0)
+       }
+       if (mkdir(git_path_seq_dir(), 0777) < 0)
                return error_errno(_("could not create sequencer directory '%s'"),
                                   git_path_seq_dir());
+
        return 0;
 }
 
 static int save_head(const char *head)
 {
-       static struct lock_file head_lock;
+       struct lock_file head_lock = LOCK_INIT;
        struct strbuf buf = STRBUF_INIT;
        int fd;
        ssize_t written;
 
        fd = hold_lock_file_for_update(&head_lock, git_path_head_file(), 0);
-       if (fd < 0) {
-               rollback_lock_file(&head_lock);
+       if (fd < 0)
                return error_errno(_("could not lock HEAD"));
-       }
        strbuf_addf(&buf, "%s\n", head);
        written = write_in_full(fd, buf.buf, buf.len);
        strbuf_release(&buf);
        if (written < 0) {
+               error_errno(_("could not write to '%s'"), git_path_head_file());
                rollback_lock_file(&head_lock);
-               return error_errno(_("could not write to '%s'"),
-                                  git_path_head_file());
-       }
-       if (commit_lock_file(&head_lock) < 0) {
-               rollback_lock_file(&head_lock);
-               return error(_("failed to finalize '%s'."), git_path_head_file());
+               return -1;
        }
+       if (commit_lock_file(&head_lock) < 0)
+               return error(_("failed to finalize '%s'"), git_path_head_file());
        return 0;
 }
 
@@ -1609,35 +2700,49 @@ static int rollback_is_safe(void)
        if (get_oid("HEAD", &actual_head))
                oidclr(&actual_head);
 
-       return !oidcmp(&actual_head, &expected_head);
+       return oideq(&actual_head, &expected_head);
 }
 
-static int reset_for_rollback(const struct object_id *oid)
+static int reset_merge(const struct object_id *oid)
 {
-       const char *argv[4];    /* reset --merge <arg> + NULL */
+       int ret;
+       struct argv_array argv = ARGV_ARRAY_INIT;
 
-       argv[0] = "reset";
-       argv[1] = "--merge";
-       argv[2] = oid_to_hex(oid);
-       argv[3] = NULL;
-       return run_command_v_opt(argv, RUN_GIT_CMD);
+       argv_array_pushl(&argv, "reset", "--merge", NULL);
+
+       if (!is_null_oid(oid))
+               argv_array_push(&argv, oid_to_hex(oid));
+
+       ret = run_command_v_opt(argv.argv, RUN_GIT_CMD);
+       argv_array_clear(&argv);
+
+       return ret;
 }
 
-static int rollback_single_pick(void)
+static int rollback_single_pick(struct repository *r)
 {
        struct object_id head_oid;
 
-       if (!file_exists(git_path_cherry_pick_head()) &&
-           !file_exists(git_path_revert_head()))
+       if (!file_exists(git_path_cherry_pick_head(r)) &&
+           !file_exists(git_path_revert_head(r)))
                return error(_("no cherry-pick or revert in progress"));
-       if (read_ref_full("HEAD", 0, head_oid.hash, NULL))
+       if (read_ref_full("HEAD", 0, &head_oid, NULL))
                return error(_("cannot resolve HEAD"));
        if (is_null_oid(&head_oid))
                return error(_("cannot abort from a branch yet to be born"));
-       return reset_for_rollback(&head_oid);
+       return reset_merge(&head_oid);
+}
+
+static int skip_single_pick(void)
+{
+       struct object_id head;
+
+       if (read_ref_full("HEAD", 0, &head, NULL))
+               return error(_("cannot resolve HEAD"));
+       return reset_merge(&head);
 }
 
-int sequencer_rollback(struct replay_opts *opts)
+int sequencer_rollback(struct repository *r, struct replay_opts *opts)
 {
        FILE *f;
        struct object_id oid;
@@ -1651,7 +2756,7 @@ int sequencer_rollback(struct replay_opts *opts)
                 * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
                 * a single-cherry-pick in progress, abort that.
                 */
-               return rollback_single_pick();
+               return rollback_single_pick(r);
        }
        if (!f)
                return error_errno(_("cannot open '%s'"), git_path_head_file());
@@ -1677,7 +2782,7 @@ int sequencer_rollback(struct replay_opts *opts)
                warning(_("You seem to have moved HEAD. "
                          "Not rewinding, check your HEAD!"));
        } else
-       if (reset_for_rollback(&oid))
+       if (reset_merge(&oid))
                goto fail;
        strbuf_release(&buf);
        return sequencer_remove_state(opts);
@@ -1686,9 +2791,73 @@ fail:
        return -1;
 }
 
+int sequencer_skip(struct repository *r, struct replay_opts *opts)
+{
+       enum replay_action action = -1;
+       sequencer_get_last_command(r, &action);
+
+       /*
+        * Check whether the subcommand requested to skip the commit is actually
+        * in progress and that it's safe to skip the commit.
+        *
+        * opts->action tells us which subcommand requested to skip the commit.
+        * If the corresponding .git/<ACTION>_HEAD exists, we know that the
+        * action is in progress and we can skip the commit.
+        *
+        * Otherwise we check that the last instruction was related to the
+        * particular subcommand we're trying to execute and barf if that's not
+        * the case.
+        *
+        * Finally we check that the rollback is "safe", i.e., has the HEAD
+        * moved? In this case, it doesn't make sense to "reset the merge" and
+        * "skip the commit" as the user already handled this by committing. But
+        * we'd not want to barf here, instead give advice on how to proceed. We
+        * only need to check that when .git/<ACTION>_HEAD doesn't exist because
+        * it gets removed when the user commits, so if it still exists we're
+        * sure the user can't have committed before.
+        */
+       switch (opts->action) {
+       case REPLAY_REVERT:
+               if (!file_exists(git_path_revert_head(r))) {
+                       if (action != REPLAY_REVERT)
+                               return error(_("no revert in progress"));
+                       if (!rollback_is_safe())
+                               goto give_advice;
+               }
+               break;
+       case REPLAY_PICK:
+               if (!file_exists(git_path_cherry_pick_head(r))) {
+                       if (action != REPLAY_PICK)
+                               return error(_("no cherry-pick in progress"));
+                       if (!rollback_is_safe())
+                               goto give_advice;
+               }
+               break;
+       default:
+               BUG("unexpected action in sequencer_skip");
+       }
+
+       if (skip_single_pick())
+               return error(_("failed to skip the commit"));
+       if (!is_directory(git_path_seq_dir()))
+               return 0;
+
+       return sequencer_continue(r, opts);
+
+give_advice:
+       error(_("there is nothing to skip"));
+
+       if (advice_resolve_conflict) {
+               advise(_("have you committed already?\n"
+                        "try \"git %s --continue\""),
+                        action == REPLAY_REVERT ? "revert" : "cherry-pick");
+       }
+       return -1;
+}
+
 static int save_todo(struct todo_list *todo_list, struct replay_opts *opts)
 {
-       static struct lock_file todo_lock;
+       struct lock_file todo_lock = LOCK_INIT;
        const char *todo_path = get_todo_path(opts);
        int next = todo_list->current, offset, fd;
 
@@ -1702,29 +2871,27 @@ static int save_todo(struct todo_list *todo_list, struct replay_opts *opts)
        fd = hold_lock_file_for_update(&todo_lock, todo_path, 0);
        if (fd < 0)
                return error_errno(_("could not lock '%s'"), todo_path);
-       offset = next < todo_list->nr ?
-               todo_list->items[next].offset_in_buf : todo_list->buf.len;
+       offset = get_item_line_offset(todo_list, next);
        if (write_in_full(fd, todo_list->buf.buf + offset,
                        todo_list->buf.len - offset) < 0)
                return error_errno(_("could not write to '%s'"), todo_path);
        if (commit_lock_file(&todo_lock) < 0)
-               return error(_("failed to finalize '%s'."), todo_path);
+               return error(_("failed to finalize '%s'"), todo_path);
 
-       if (is_rebase_i(opts)) {
-               const char *done_path = rebase_path_done();
-               int fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
-               int prev_offset = !next ? 0 :
-                       todo_list->items[next - 1].offset_in_buf;
+       if (is_rebase_i(opts) && next > 0) {
+               const char *done = rebase_path_done();
+               int fd = open(done, O_CREAT | O_WRONLY | O_APPEND, 0666);
+               int ret = 0;
 
-               if (fd >= 0 && offset > prev_offset &&
-                   write_in_full(fd, todo_list->buf.buf + prev_offset,
-                                 offset - prev_offset) < 0) {
-                       close(fd);
-                       return error_errno(_("could not write to '%s'"),
-                                          done_path);
-               }
-               if (fd >= 0)
-                       close(fd);
+               if (fd < 0)
+                       return 0;
+               if (write_in_full(fd, get_item_line(todo_list, next - 1),
+                                 get_item_line_length(todo_list, next - 1))
+                   < 0)
+                       ret = error_errno(_("could not write to '%s'"), done);
+               if (close(fd) < 0)
+                       ret = error_errno(_("failed to finalize '%s'"), done);
+               return ret;
        }
        return 0;
 }
@@ -1735,40 +2902,65 @@ static int save_opts(struct replay_opts *opts)
        int res = 0;
 
        if (opts->no_commit)
-               res |= git_config_set_in_file_gently(opts_file, "options.no-commit", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.no-commit", "true");
        if (opts->edit)
-               res |= git_config_set_in_file_gently(opts_file, "options.edit", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.edit", "true");
+       if (opts->allow_empty)
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.allow-empty", "true");
+       if (opts->allow_empty_message)
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.allow-empty-message", "true");
+       if (opts->keep_redundant_commits)
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.keep-redundant-commits", "true");
        if (opts->signoff)
-               res |= git_config_set_in_file_gently(opts_file, "options.signoff", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.signoff", "true");
        if (opts->record_origin)
-               res |= git_config_set_in_file_gently(opts_file, "options.record-origin", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.record-origin", "true");
        if (opts->allow_ff)
-               res |= git_config_set_in_file_gently(opts_file, "options.allow-ff", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.allow-ff", "true");
        if (opts->mainline) {
                struct strbuf buf = STRBUF_INIT;
                strbuf_addf(&buf, "%d", opts->mainline);
-               res |= git_config_set_in_file_gently(opts_file, "options.mainline", buf.buf);
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.mainline", buf.buf);
                strbuf_release(&buf);
        }
        if (opts->strategy)
-               res |= git_config_set_in_file_gently(opts_file, "options.strategy", opts->strategy);
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.strategy", opts->strategy);
        if (opts->gpg_sign)
-               res |= git_config_set_in_file_gently(opts_file, "options.gpg-sign", opts->gpg_sign);
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.gpg-sign", opts->gpg_sign);
        if (opts->xopts) {
                int i;
                for (i = 0; i < opts->xopts_nr; i++)
                        res |= git_config_set_multivar_in_file_gently(opts_file,
-                                                       "options.strategy-option",
-                                                       opts->xopts[i], "^$", 0);
+                                       "options.strategy-option",
+                                       opts->xopts[i], "^$", 0);
        }
        if (opts->allow_rerere_auto)
-               res |= git_config_set_in_file_gently(opts_file, "options.allow-rerere-auto",
-                                                    opts->allow_rerere_auto == RERERE_AUTOUPDATE ?
-                                                    "true" : "false");
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.allow-rerere-auto",
+                               opts->allow_rerere_auto == RERERE_AUTOUPDATE ?
+                               "true" : "false");
+
+       if (opts->explicit_cleanup)
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.default-msg-cleanup",
+                               describe_cleanup_mode(opts->default_msg_cleanup));
        return res;
 }
 
-static int make_patch(struct commit *commit, struct replay_opts *opts)
+static int make_patch(struct repository *r,
+                     struct commit *commit,
+                     struct replay_opts *opts)
 {
        struct strbuf buf = STRBUF_INIT;
        struct rev_info log_tree_opt;
@@ -1778,10 +2970,13 @@ static int make_patch(struct commit *commit, struct replay_opts *opts)
        p = short_commit_name(commit);
        if (write_message(p, strlen(p), rebase_path_stopped_sha(), 1) < 0)
                return -1;
+       if (update_ref("rebase", "REBASE_HEAD", &commit->object.oid,
+                      NULL, REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR))
+               res |= error(_("could not update %s"), "REBASE_HEAD");
 
        strbuf_addf(&buf, "%s/patch", get_dir(opts));
        memset(&log_tree_opt, 0, sizeof(log_tree_opt));
-       init_revisions(&log_tree_opt, NULL);
+       repo_init_revisions(r, &log_tree_opt, NULL);
        log_tree_opt.abbrev = 0;
        log_tree_opt.diff = 1;
        log_tree_opt.diffopt.output_format = DIFF_FORMAT_PATCH;
@@ -1799,7 +2994,8 @@ static int make_patch(struct commit *commit, struct replay_opts *opts)
 
        strbuf_addf(&buf, "%s/message", get_dir(opts));
        if (!file_exists(buf.buf)) {
-               const char *commit_buffer = get_commit_buffer(commit, NULL);
+               const char *encoding = get_commit_output_encoding();
+               const char *commit_buffer = logmsg_reencode(commit, NULL, encoding);
                find_commit_subject(commit_buffer, &subject);
                res |= write_message(subject, strlen(subject), buf.buf, 1);
                unuse_commit_buffer(commit, commit_buffer);
@@ -1821,59 +3017,85 @@ static int intend_to_amend(void)
        return write_message(p, strlen(p), rebase_path_amend(), 1);
 }
 
-static int error_with_patch(struct commit *commit,
-       const char *subject, int subject_len,
-       struct replay_opts *opts, int exit_code, int to_amend)
+static int error_with_patch(struct repository *r,
+                           struct commit *commit,
+                           const char *subject, int subject_len,
+                           struct replay_opts *opts,
+                           int exit_code, int to_amend)
 {
-       if (make_patch(commit, opts))
-               return -1;
+       if (commit) {
+               if (make_patch(r, commit, opts))
+                       return -1;
+       } else if (copy_file(rebase_path_message(),
+                            git_path_merge_msg(r), 0666))
+               return error(_("unable to copy '%s' to '%s'"),
+                            git_path_merge_msg(r), rebase_path_message());
 
        if (to_amend) {
                if (intend_to_amend())
                        return -1;
 
-               fprintf(stderr, "You can amend the commit now, with\n"
-                       "\n"
-                       "  git commit --amend %s\n"
-                       "\n"
-                       "Once you are satisfied with your changes, run\n"
-                       "\n"
-                       "  git rebase --continue\n", gpg_sign_opt_quoted(opts));
-       } else if (exit_code)
-               fprintf(stderr, "Could not apply %s... %.*s\n",
-                       short_commit_name(commit), subject_len, subject);
+               fprintf(stderr,
+                       _("You can amend the commit now, with\n"
+                         "\n"
+                         "  git commit --amend %s\n"
+                         "\n"
+                         "Once you are satisfied with your changes, run\n"
+                         "\n"
+                         "  git rebase --continue\n"),
+                       gpg_sign_opt_quoted(opts));
+       } else if (exit_code) {
+               if (commit)
+                       fprintf_ln(stderr, _("Could not apply %s... %.*s"),
+                                  short_commit_name(commit), subject_len, subject);
+               else
+                       /*
+                        * We don't have the hash of the parent so
+                        * just print the line from the todo file.
+                        */
+                       fprintf_ln(stderr, _("Could not merge %.*s"),
+                                  subject_len, subject);
+       }
 
        return exit_code;
 }
 
-static int error_failed_squash(struct commit *commit,
-       struct replay_opts *opts, int subject_len, const char *subject)
+static int error_failed_squash(struct repository *r,
+                              struct commit *commit,
+                              struct replay_opts *opts,
+                              int subject_len,
+                              const char *subject)
 {
-       if (rename(rebase_path_squash_msg(), rebase_path_message()))
-               return error(_("could not rename '%s' to '%s'"),
+       if (copy_file(rebase_path_message(), rebase_path_squash_msg(), 0666))
+               return error(_("could not copy '%s' to '%s'"),
                        rebase_path_squash_msg(), rebase_path_message());
-       unlink(rebase_path_fixup_msg());
-       unlink(git_path_merge_msg());
-       if (copy_file(git_path_merge_msg(), rebase_path_message(), 0666))
+       unlink(git_path_merge_msg(r));
+       if (copy_file(git_path_merge_msg(r), rebase_path_message(), 0666))
                return error(_("could not copy '%s' to '%s'"),
-                            rebase_path_message(), git_path_merge_msg());
-       return error_with_patch(commit, subject, subject_len, opts, 1, 0);
+                            rebase_path_message(),
+                            git_path_merge_msg(r));
+       return error_with_patch(r, commit, subject, subject_len, opts, 1, 0);
 }
 
-static int do_exec(const char *command_line)
+static int do_exec(struct repository *r, const char *command_line)
 {
+       struct argv_array child_env = ARGV_ARRAY_INIT;
        const char *child_argv[] = { NULL, NULL };
        int dirty, status;
 
        fprintf(stderr, "Executing: %s\n", command_line);
        child_argv[0] = command_line;
-       status = run_command_v_opt(child_argv, RUN_USING_SHELL);
+       argv_array_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
+       argv_array_pushf(&child_env, "GIT_WORK_TREE=%s",
+                        absolute_path(get_git_work_tree()));
+       status = run_command_v_opt_cd_env(child_argv, RUN_USING_SHELL, NULL,
+                                         child_env.argv);
 
        /* force re-reading of the cache */
-       if (discard_cache() < 0 || read_cache() < 0)
+       if (discard_index(r->index) < 0 || repo_read_index(r) < 0)
                return error(_("could not read index"));
 
-       dirty = require_clean_work_tree("rebase", NULL, 1, 1);
+       dirty = require_clean_work_tree(r, "rebase", NULL, 1, 1);
 
        if (status) {
                warning(_("execution failed: %s\n%s"
@@ -1897,46 +3119,527 @@ static int do_exec(const char *command_line)
                status = 1;
        }
 
+       argv_array_clear(&child_env);
+
        return status;
 }
 
-static int is_final_fixup(struct todo_list *todo_list)
+static int safe_append(const char *filename, const char *fmt, ...)
 {
-       int i = todo_list->current;
+       va_list ap;
+       struct lock_file lock = LOCK_INIT;
+       int fd = hold_lock_file_for_update(&lock, filename,
+                                          LOCK_REPORT_ON_ERROR);
+       struct strbuf buf = STRBUF_INIT;
 
-       if (!is_fixup(todo_list->items[i].command))
-               return 0;
+       if (fd < 0)
+               return -1;
 
-       while (++i < todo_list->nr)
-               if (is_fixup(todo_list->items[i].command))
-                       return 0;
-               else if (!is_noop(todo_list->items[i].command))
-                       break;
-       return 1;
+       if (strbuf_read_file(&buf, filename, 0) < 0 && errno != ENOENT) {
+               error_errno(_("could not read '%s'"), filename);
+               rollback_lock_file(&lock);
+               return -1;
+       }
+       strbuf_complete(&buf, '\n');
+       va_start(ap, fmt);
+       strbuf_vaddf(&buf, fmt, ap);
+       va_end(ap);
+
+       if (write_in_full(fd, buf.buf, buf.len) < 0) {
+               error_errno(_("could not write to '%s'"), filename);
+               strbuf_release(&buf);
+               rollback_lock_file(&lock);
+               return -1;
+       }
+       if (commit_lock_file(&lock) < 0) {
+               strbuf_release(&buf);
+               rollback_lock_file(&lock);
+               return error(_("failed to finalize '%s'"), filename);
+       }
+
+       strbuf_release(&buf);
+       return 0;
 }
 
-static enum todo_command peek_command(struct todo_list *todo_list, int offset)
+static int do_label(struct repository *r, const char *name, int len)
 {
-       int i;
+       struct ref_store *refs = get_main_ref_store(r);
+       struct ref_transaction *transaction;
+       struct strbuf ref_name = STRBUF_INIT, err = STRBUF_INIT;
+       struct strbuf msg = STRBUF_INIT;
+       int ret = 0;
+       struct object_id head_oid;
 
-       for (i = todo_list->current + offset; i < todo_list->nr; i++)
-               if (!is_noop(todo_list->items[i].command))
-                       return todo_list->items[i].command;
+       if (len == 1 && *name == '#')
+               return error(_("illegal label name: '%.*s'"), len, name);
 
-       return -1;
+       strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
+       strbuf_addf(&msg, "rebase -i (label) '%.*s'", len, name);
+
+       transaction = ref_store_transaction_begin(refs, &err);
+       if (!transaction) {
+               error("%s", err.buf);
+               ret = -1;
+       } else if (get_oid("HEAD", &head_oid)) {
+               error(_("could not read HEAD"));
+               ret = -1;
+       } else if (ref_transaction_update(transaction, ref_name.buf, &head_oid,
+                                         NULL, 0, msg.buf, &err) < 0 ||
+                  ref_transaction_commit(transaction, &err)) {
+               error("%s", err.buf);
+               ret = -1;
+       }
+       ref_transaction_free(transaction);
+       strbuf_release(&err);
+       strbuf_release(&msg);
+
+       if (!ret)
+               ret = safe_append(rebase_path_refs_to_delete(),
+                                 "%s\n", ref_name.buf);
+       strbuf_release(&ref_name);
+
+       return ret;
 }
 
-static int apply_autostash(struct replay_opts *opts)
+static const char *reflog_message(struct replay_opts *opts,
+       const char *sub_action, const char *fmt, ...);
+
+static int do_reset(struct repository *r,
+                   const char *name, int len,
+                   struct replay_opts *opts)
 {
-       struct strbuf stash_sha1 = STRBUF_INIT;
-       struct child_process child = CHILD_PROCESS_INIT;
+       struct strbuf ref_name = STRBUF_INIT;
+       struct object_id oid;
+       struct lock_file lock = LOCK_INIT;
+       struct tree_desc desc;
+       struct tree *tree;
+       struct unpack_trees_options unpack_tree_opts;
        int ret = 0;
 
-       if (!read_oneliner(&stash_sha1, rebase_path_autostash(), 1)) {
-               strbuf_release(&stash_sha1);
-               return 0;
-       }
-       strbuf_trim(&stash_sha1);
+       if (repo_hold_locked_index(r, &lock, LOCK_REPORT_ON_ERROR) < 0)
+               return -1;
+
+       if (len == 10 && !strncmp("[new root]", name, len)) {
+               if (!opts->have_squash_onto) {
+                       const char *hex;
+                       if (commit_tree("", 0, the_hash_algo->empty_tree,
+                                       NULL, &opts->squash_onto,
+                                       NULL, NULL))
+                               return error(_("writing fake root commit"));
+                       opts->have_squash_onto = 1;
+                       hex = oid_to_hex(&opts->squash_onto);
+                       if (write_message(hex, strlen(hex),
+                                         rebase_path_squash_onto(), 0))
+                               return error(_("writing squash-onto"));
+               }
+               oidcpy(&oid, &opts->squash_onto);
+       } else {
+               int i;
+
+               /* Determine the length of the label */
+               for (i = 0; i < len; i++)
+                       if (isspace(name[i]))
+                               break;
+               len = i;
+
+               strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
+               if (get_oid(ref_name.buf, &oid) &&
+                   get_oid(ref_name.buf + strlen("refs/rewritten/"), &oid)) {
+                       error(_("could not read '%s'"), ref_name.buf);
+                       rollback_lock_file(&lock);
+                       strbuf_release(&ref_name);
+                       return -1;
+               }
+       }
+
+       memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
+       setup_unpack_trees_porcelain(&unpack_tree_opts, "reset");
+       unpack_tree_opts.head_idx = 1;
+       unpack_tree_opts.src_index = r->index;
+       unpack_tree_opts.dst_index = r->index;
+       unpack_tree_opts.fn = oneway_merge;
+       unpack_tree_opts.merge = 1;
+       unpack_tree_opts.update = 1;
+
+       if (repo_read_index_unmerged(r)) {
+               rollback_lock_file(&lock);
+               strbuf_release(&ref_name);
+               return error_resolve_conflict(_(action_name(opts)));
+       }
+
+       if (!fill_tree_descriptor(r, &desc, &oid)) {
+               error(_("failed to find tree of %s"), oid_to_hex(&oid));
+               rollback_lock_file(&lock);
+               free((void *)desc.buffer);
+               strbuf_release(&ref_name);
+               return -1;
+       }
+
+       if (unpack_trees(1, &desc, &unpack_tree_opts)) {
+               rollback_lock_file(&lock);
+               free((void *)desc.buffer);
+               strbuf_release(&ref_name);
+               return -1;
+       }
+
+       tree = parse_tree_indirect(&oid);
+       prime_cache_tree(r, r->index, tree);
+
+       if (write_locked_index(r->index, &lock, COMMIT_LOCK) < 0)
+               ret = error(_("could not write index"));
+       free((void *)desc.buffer);
+
+       if (!ret)
+               ret = update_ref(reflog_message(opts, "reset", "'%.*s'",
+                                               len, name), "HEAD", &oid,
+                                NULL, 0, UPDATE_REFS_MSG_ON_ERR);
+
+       strbuf_release(&ref_name);
+       return ret;
+}
+
+static struct commit *lookup_label(const char *label, int len,
+                                  struct strbuf *buf)
+{
+       struct commit *commit;
+
+       strbuf_reset(buf);
+       strbuf_addf(buf, "refs/rewritten/%.*s", len, label);
+       commit = lookup_commit_reference_by_name(buf->buf);
+       if (!commit) {
+               /* fall back to non-rewritten ref or commit */
+               strbuf_splice(buf, 0, strlen("refs/rewritten/"), "", 0);
+               commit = lookup_commit_reference_by_name(buf->buf);
+       }
+
+       if (!commit)
+               error(_("could not resolve '%s'"), buf->buf);
+
+       return commit;
+}
+
+static int do_merge(struct repository *r,
+                   struct commit *commit,
+                   const char *arg, int arg_len,
+                   int flags, struct replay_opts *opts)
+{
+       int run_commit_flags = (flags & TODO_EDIT_MERGE_MSG) ?
+               EDIT_MSG | VERIFY_MSG : 0;
+       struct strbuf ref_name = STRBUF_INIT;
+       struct commit *head_commit, *merge_commit, *i;
+       struct commit_list *bases, *j, *reversed = NULL;
+       struct commit_list *to_merge = NULL, **tail = &to_merge;
+       const char *strategy = !opts->xopts_nr &&
+               (!opts->strategy || !strcmp(opts->strategy, "recursive")) ?
+               NULL : opts->strategy;
+       struct merge_options o;
+       int merge_arg_len, oneline_offset, can_fast_forward, ret, k;
+       static struct lock_file lock;
+       const char *p;
+
+       if (repo_hold_locked_index(r, &lock, LOCK_REPORT_ON_ERROR) < 0) {
+               ret = -1;
+               goto leave_merge;
+       }
+
+       head_commit = lookup_commit_reference_by_name("HEAD");
+       if (!head_commit) {
+               ret = error(_("cannot merge without a current revision"));
+               goto leave_merge;
+       }
+
+       /*
+        * For octopus merges, the arg starts with the list of revisions to be
+        * merged. The list is optionally followed by '#' and the oneline.
+        */
+       merge_arg_len = oneline_offset = arg_len;
+       for (p = arg; p - arg < arg_len; p += strspn(p, " \t\n")) {
+               if (!*p)
+                       break;
+               if (*p == '#' && (!p[1] || isspace(p[1]))) {
+                       p += 1 + strspn(p + 1, " \t\n");
+                       oneline_offset = p - arg;
+                       break;
+               }
+               k = strcspn(p, " \t\n");
+               if (!k)
+                       continue;
+               merge_commit = lookup_label(p, k, &ref_name);
+               if (!merge_commit) {
+                       ret = error(_("unable to parse '%.*s'"), k, p);
+                       goto leave_merge;
+               }
+               tail = &commit_list_insert(merge_commit, tail)->next;
+               p += k;
+               merge_arg_len = p - arg;
+       }
+
+       if (!to_merge) {
+               ret = error(_("nothing to merge: '%.*s'"), arg_len, arg);
+               goto leave_merge;
+       }
+
+       if (opts->have_squash_onto &&
+           oideq(&head_commit->object.oid, &opts->squash_onto)) {
+               /*
+                * When the user tells us to "merge" something into a
+                * "[new root]", let's simply fast-forward to the merge head.
+                */
+               rollback_lock_file(&lock);
+               if (to_merge->next)
+                       ret = error(_("octopus merge cannot be executed on "
+                                     "top of a [new root]"));
+               else
+                       ret = fast_forward_to(r, &to_merge->item->object.oid,
+                                             &head_commit->object.oid, 0,
+                                             opts);
+               goto leave_merge;
+       }
+
+       if (commit) {
+               const char *encoding = get_commit_output_encoding();
+               const char *message = logmsg_reencode(commit, NULL, encoding);
+               const char *body;
+               int len;
+
+               if (!message) {
+                       ret = error(_("could not get commit message of '%s'"),
+                                   oid_to_hex(&commit->object.oid));
+                       goto leave_merge;
+               }
+               write_author_script(message);
+               find_commit_subject(message, &body);
+               len = strlen(body);
+               ret = write_message(body, len, git_path_merge_msg(r), 0);
+               unuse_commit_buffer(commit, message);
+               if (ret) {
+                       error_errno(_("could not write '%s'"),
+                                   git_path_merge_msg(r));
+                       goto leave_merge;
+               }
+       } else {
+               struct strbuf buf = STRBUF_INIT;
+               int len;
+
+               strbuf_addf(&buf, "author %s", git_author_info(0));
+               write_author_script(buf.buf);
+               strbuf_reset(&buf);
+
+               if (oneline_offset < arg_len) {
+                       p = arg + oneline_offset;
+                       len = arg_len - oneline_offset;
+               } else {
+                       strbuf_addf(&buf, "Merge %s '%.*s'",
+                                   to_merge->next ? "branches" : "branch",
+                                   merge_arg_len, arg);
+                       p = buf.buf;
+                       len = buf.len;
+               }
+
+               ret = write_message(p, len, git_path_merge_msg(r), 0);
+               strbuf_release(&buf);
+               if (ret) {
+                       error_errno(_("could not write '%s'"),
+                                   git_path_merge_msg(r));
+                       goto leave_merge;
+               }
+       }
+
+       /*
+        * If HEAD is not identical to the first parent of the original merge
+        * commit, we cannot fast-forward.
+        */
+       can_fast_forward = opts->allow_ff && commit && commit->parents &&
+               oideq(&commit->parents->item->object.oid,
+                     &head_commit->object.oid);
+
+       /*
+        * If any merge head is different from the original one, we cannot
+        * fast-forward.
+        */
+       if (can_fast_forward) {
+               struct commit_list *p = commit->parents->next;
+
+               for (j = to_merge; j && p; j = j->next, p = p->next)
+                       if (!oideq(&j->item->object.oid,
+                                  &p->item->object.oid)) {
+                               can_fast_forward = 0;
+                               break;
+                       }
+               /*
+                * If the number of merge heads differs from the original merge
+                * commit, we cannot fast-forward.
+                */
+               if (j || p)
+                       can_fast_forward = 0;
+       }
+
+       if (can_fast_forward) {
+               rollback_lock_file(&lock);
+               ret = fast_forward_to(r, &commit->object.oid,
+                                     &head_commit->object.oid, 0, opts);
+               if (flags & TODO_EDIT_MERGE_MSG) {
+                       run_commit_flags |= AMEND_MSG;
+                       goto fast_forward_edit;
+               }
+               goto leave_merge;
+       }
+
+       if (strategy || to_merge->next) {
+               /* Octopus merge */
+               struct child_process cmd = CHILD_PROCESS_INIT;
+
+               if (read_env_script(&cmd.env_array)) {
+                       const char *gpg_opt = gpg_sign_opt_quoted(opts);
+
+                       ret = error(_(staged_changes_advice), gpg_opt, gpg_opt);
+                       goto leave_merge;
+               }
+
+               cmd.git_cmd = 1;
+               argv_array_push(&cmd.args, "merge");
+               argv_array_push(&cmd.args, "-s");
+               if (!strategy)
+                       argv_array_push(&cmd.args, "octopus");
+               else {
+                       argv_array_push(&cmd.args, strategy);
+                       for (k = 0; k < opts->xopts_nr; k++)
+                               argv_array_pushf(&cmd.args,
+                                                "-X%s", opts->xopts[k]);
+               }
+               argv_array_push(&cmd.args, "--no-edit");
+               argv_array_push(&cmd.args, "--no-ff");
+               argv_array_push(&cmd.args, "--no-log");
+               argv_array_push(&cmd.args, "--no-stat");
+               argv_array_push(&cmd.args, "-F");
+               argv_array_push(&cmd.args, git_path_merge_msg(r));
+               if (opts->gpg_sign)
+                       argv_array_push(&cmd.args, opts->gpg_sign);
+
+               /* Add the tips to be merged */
+               for (j = to_merge; j; j = j->next)
+                       argv_array_push(&cmd.args,
+                                       oid_to_hex(&j->item->object.oid));
+
+               strbuf_release(&ref_name);
+               unlink(git_path_cherry_pick_head(r));
+               rollback_lock_file(&lock);
+
+               rollback_lock_file(&lock);
+               ret = run_command(&cmd);
+
+               /* force re-reading of the cache */
+               if (!ret && (discard_index(r->index) < 0 ||
+                            repo_read_index(r) < 0))
+                       ret = error(_("could not read index"));
+               goto leave_merge;
+       }
+
+       merge_commit = to_merge->item;
+       bases = get_merge_bases(head_commit, merge_commit);
+       if (bases && oideq(&merge_commit->object.oid,
+                          &bases->item->object.oid)) {
+               ret = 0;
+               /* skip merging an ancestor of HEAD */
+               goto leave_merge;
+       }
+
+       write_message(oid_to_hex(&merge_commit->object.oid), the_hash_algo->hexsz,
+                     git_path_merge_head(r), 0);
+       write_message("no-ff", 5, git_path_merge_mode(r), 0);
+
+       for (j = bases; j; j = j->next)
+               commit_list_insert(j->item, &reversed);
+       free_commit_list(bases);
+
+       repo_read_index(r);
+       init_merge_options(&o, r);
+       o.branch1 = "HEAD";
+       o.branch2 = ref_name.buf;
+       o.buffer_output = 2;
+
+       ret = merge_recursive(&o, head_commit, merge_commit, reversed, &i);
+       if (ret <= 0)
+               fputs(o.obuf.buf, stdout);
+       strbuf_release(&o.obuf);
+       if (ret < 0) {
+               error(_("could not even attempt to merge '%.*s'"),
+                     merge_arg_len, arg);
+               goto leave_merge;
+       }
+       /*
+        * The return value of merge_recursive() is 1 on clean, and 0 on
+        * unclean merge.
+        *
+        * Let's reverse that, so that do_merge() returns 0 upon success and
+        * 1 upon failed merge (keeping the return value -1 for the cases where
+        * we will want to reschedule the `merge` command).
+        */
+       ret = !ret;
+
+       if (r->index->cache_changed &&
+           write_locked_index(r->index, &lock, COMMIT_LOCK)) {
+               ret = error(_("merge: Unable to write new index file"));
+               goto leave_merge;
+       }
+
+       rollback_lock_file(&lock);
+       if (ret)
+               repo_rerere(r, opts->allow_rerere_auto);
+       else
+               /*
+                * In case of problems, we now want to return a positive
+                * value (a negative one would indicate that the `merge`
+                * command needs to be rescheduled).
+                */
+       fast_forward_edit:
+               ret = !!run_git_commit(r, git_path_merge_msg(r), opts,
+                                      run_commit_flags);
+
+leave_merge:
+       strbuf_release(&ref_name);
+       rollback_lock_file(&lock);
+       free_commit_list(to_merge);
+       return ret;
+}
+
+static int is_final_fixup(struct todo_list *todo_list)
+{
+       int i = todo_list->current;
+
+       if (!is_fixup(todo_list->items[i].command))
+               return 0;
+
+       while (++i < todo_list->nr)
+               if (is_fixup(todo_list->items[i].command))
+                       return 0;
+               else if (!is_noop(todo_list->items[i].command))
+                       break;
+       return 1;
+}
+
+static enum todo_command peek_command(struct todo_list *todo_list, int offset)
+{
+       int i;
+
+       for (i = todo_list->current + offset; i < todo_list->nr; i++)
+               if (!is_noop(todo_list->items[i].command))
+                       return todo_list->items[i].command;
+
+       return -1;
+}
+
+static int apply_autostash(struct replay_opts *opts)
+{
+       struct strbuf stash_sha1 = STRBUF_INIT;
+       struct child_process child = CHILD_PROCESS_INIT;
+       int ret = 0;
+
+       if (!read_oneliner(&stash_sha1, rebase_path_autostash(), 1)) {
+               strbuf_release(&stash_sha1);
+               return 0;
+       }
+       strbuf_trim(&stash_sha1);
 
        child.git_cmd = 1;
        child.no_stdout = 1;
@@ -1990,19 +3693,109 @@ static const char *reflog_message(struct replay_opts *opts,
        return buf.buf;
 }
 
-static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
+static int run_git_checkout(struct repository *r, struct replay_opts *opts,
+                           const char *commit, const char *action)
 {
-       int res = 0;
+       struct child_process cmd = CHILD_PROCESS_INIT;
+       int ret;
+
+       cmd.git_cmd = 1;
+
+       argv_array_push(&cmd.args, "checkout");
+       argv_array_push(&cmd.args, commit);
+       argv_array_pushf(&cmd.env_array, GIT_REFLOG_ACTION "=%s", action);
+
+       if (opts->verbose)
+               ret = run_command(&cmd);
+       else
+               ret = run_command_silent_on_success(&cmd);
+
+       if (!ret)
+               discard_index(r->index);
+
+       return ret;
+}
+
+int prepare_branch_to_be_rebased(struct repository *r, struct replay_opts *opts,
+                                const char *commit)
+{
+       const char *action;
+
+       if (commit && *commit) {
+               action = reflog_message(opts, "start", "checkout %s", commit);
+               if (run_git_checkout(r, opts, commit, action))
+                       return error(_("could not checkout %s"), commit);
+       }
+
+       return 0;
+}
+
+static int checkout_onto(struct repository *r, struct replay_opts *opts,
+                        const char *onto_name, const struct object_id *onto,
+                        const char *orig_head)
+{
+       struct object_id oid;
+       const char *action = reflog_message(opts, "start", "checkout %s", onto_name);
+
+       if (get_oid(orig_head, &oid))
+               return error(_("%s: not a valid OID"), orig_head);
+
+       if (run_git_checkout(r, opts, oid_to_hex(onto), action)) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+               return error(_("could not detach HEAD"));
+       }
+
+       return update_ref(NULL, "ORIG_HEAD", &oid, NULL, 0, UPDATE_REFS_MSG_ON_ERR);
+}
+
+static int stopped_at_head(struct repository *r)
+{
+       struct object_id head;
+       struct commit *commit;
+       struct commit_message message;
+
+       if (get_oid("HEAD", &head) ||
+           !(commit = lookup_commit(r, &head)) ||
+           parse_commit(commit) || get_message(commit, &message))
+               fprintf(stderr, _("Stopped at HEAD\n"));
+       else {
+               fprintf(stderr, _("Stopped at %s\n"), message.label);
+               free_message(commit, &message);
+       }
+       return 0;
+
+}
+
+static const char rescheduled_advice[] =
+N_("Could not execute the todo command\n"
+"\n"
+"    %.*s"
+"\n"
+"It has been rescheduled; To edit the command before continuing, please\n"
+"edit the todo list first:\n"
+"\n"
+"    git rebase --edit-todo\n"
+"    git rebase --continue\n");
+
+static int pick_commits(struct repository *r,
+                       struct todo_list *todo_list,
+                       struct replay_opts *opts)
+{
+       int res = 0, reschedule = 0;
 
        setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
        if (opts->allow_ff)
                assert(!(opts->signoff || opts->no_commit ||
                                opts->record_origin || opts->edit));
-       if (read_and_refresh_cache(opts))
+       if (read_and_refresh_cache(r, opts))
                return -1;
 
        while (todo_list->current < todo_list->nr) {
                struct todo_item *item = todo_list->items + todo_list->current;
+               const char *arg = todo_item_get_arg(todo_list, item);
+               int check_todo = 0;
+
                if (save_todo(todo_list, opts))
                        return -1;
                if (is_rebase_i(opts)) {
@@ -2015,39 +3808,56 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                        fprintf(f, "%d\n", todo_list->done_nr);
                                        fclose(f);
                                }
-                               fprintf(stderr, "Rebasing (%d/%d)%s",
-                                       todo_list->done_nr,
-                                       todo_list->total_nr,
-                                       opts->verbose ? "\n" : "\r");
+                               if (!opts->quiet)
+                                       fprintf(stderr, "Rebasing (%d/%d)%s",
+                                               todo_list->done_nr,
+                                               todo_list->total_nr,
+                                               opts->verbose ? "\n" : "\r");
                        }
                        unlink(rebase_path_message());
                        unlink(rebase_path_author_script());
                        unlink(rebase_path_stopped_sha());
                        unlink(rebase_path_amend());
+                       unlink(git_path_merge_head(r));
+                       delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
+
+                       if (item->command == TODO_BREAK) {
+                               if (!opts->verbose)
+                                       term_clear_line();
+                               return stopped_at_head(r);
+                       }
                }
                if (item->command <= TODO_SQUASH) {
                        if (is_rebase_i(opts))
                                setenv("GIT_REFLOG_ACTION", reflog_message(opts,
                                        command_to_string(item->command), NULL),
                                        1);
-                       res = do_pick_commit(item->command, item->commit,
-                                       opts, is_final_fixup(todo_list));
+                       res = do_pick_commit(r, item->command, item->commit,
+                                            opts, is_final_fixup(todo_list),
+                                            &check_todo);
                        if (is_rebase_i(opts) && res < 0) {
                                /* Reschedule */
+                               advise(_(rescheduled_advice),
+                                      get_item_line_length(todo_list,
+                                                           todo_list->current),
+                                      get_item_line(todo_list,
+                                                    todo_list->current));
                                todo_list->current--;
                                if (save_todo(todo_list, opts))
                                        return -1;
                        }
                        if (item->command == TODO_EDIT) {
                                struct commit *commit = item->commit;
-                               if (!res)
+                               if (!res) {
+                                       if (!opts->verbose)
+                                               term_clear_line();
                                        fprintf(stderr,
                                                _("Stopped at %s...  %.*s\n"),
                                                short_commit_name(commit),
-                                               item->arg_len, item->arg);
-                               return error_with_patch(commit,
-                                       item->arg, item->arg_len, opts, res,
-                                       !res);
+                                               item->arg_len, arg);
+                               }
+                               return error_with_patch(r, commit,
+                                       arg, item->arg_len, opts, res, !res);
                        }
                        if (is_rebase_i(opts) && !res)
                                record_in_rewritten(&item->commit->object.oid,
@@ -2055,36 +3865,94 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                        if (res && is_fixup(item->command)) {
                                if (res == 1)
                                        intend_to_amend();
-                               return error_failed_squash(item->commit, opts,
-                                       item->arg_len, item->arg);
-                       } else if (res && is_rebase_i(opts))
-                               return res | error_with_patch(item->commit,
-                                       item->arg, item->arg_len, opts, res,
-                                       item->command == TODO_REWORD);
+                               return error_failed_squash(r, item->commit, opts,
+                                       item->arg_len, arg);
+                       } else if (res && is_rebase_i(opts) && item->commit) {
+                               int to_amend = 0;
+                               struct object_id oid;
+
+                               /*
+                                * If we are rewording and have either
+                                * fast-forwarded already, or are about to
+                                * create a new root commit, we want to amend,
+                                * otherwise we do not.
+                                */
+                               if (item->command == TODO_REWORD &&
+                                   !get_oid("HEAD", &oid) &&
+                                   (oideq(&item->commit->object.oid, &oid) ||
+                                    (opts->have_squash_onto &&
+                                     oideq(&opts->squash_onto, &oid))))
+                                       to_amend = 1;
+
+                               return res | error_with_patch(r, item->commit,
+                                               arg, item->arg_len, opts,
+                                               res, to_amend);
+                       }
                } else if (item->command == TODO_EXEC) {
-                       char *end_of_arg = (char *)(item->arg + item->arg_len);
+                       char *end_of_arg = (char *)(arg + item->arg_len);
                        int saved = *end_of_arg;
-                       struct stat st;
 
+                       if (!opts->verbose)
+                               term_clear_line();
                        *end_of_arg = '\0';
-                       res = do_exec(item->arg);
+                       res = do_exec(r, arg);
                        *end_of_arg = saved;
 
-                       /* Reread the todo file if it has changed. */
-                       if (res)
-                               ; /* fall through */
-                       else if (stat(get_todo_path(opts), &st))
+                       if (res) {
+                               if (opts->reschedule_failed_exec)
+                                       reschedule = 1;
+                       }
+                       check_todo = 1;
+               } else if (item->command == TODO_LABEL) {
+                       if ((res = do_label(r, arg, item->arg_len)))
+                               reschedule = 1;
+               } else if (item->command == TODO_RESET) {
+                       if ((res = do_reset(r, arg, item->arg_len, opts)))
+                               reschedule = 1;
+               } else if (item->command == TODO_MERGE) {
+                       if ((res = do_merge(r, item->commit,
+                                           arg, item->arg_len,
+                                           item->flags, opts)) < 0)
+                               reschedule = 1;
+                       else if (item->commit)
+                               record_in_rewritten(&item->commit->object.oid,
+                                                   peek_command(todo_list, 1));
+                       if (res > 0)
+                               /* failed with merge conflicts */
+                               return error_with_patch(r, item->commit,
+                                                       arg, item->arg_len,
+                                                       opts, res, 0);
+               } else if (!is_noop(item->command))
+                       return error(_("unknown command %d"), item->command);
+
+               if (reschedule) {
+                       advise(_(rescheduled_advice),
+                              get_item_line_length(todo_list,
+                                                   todo_list->current),
+                              get_item_line(todo_list, todo_list->current));
+                       todo_list->current--;
+                       if (save_todo(todo_list, opts))
+                               return -1;
+                       if (item->commit)
+                               return error_with_patch(r,
+                                                       item->commit,
+                                                       arg, item->arg_len,
+                                                       opts, res, 0);
+               } else if (is_rebase_i(opts) && check_todo && !res) {
+                       struct stat st;
+
+                       if (stat(get_todo_path(opts), &st)) {
                                res = error_errno(_("could not stat '%s'"),
                                                  get_todo_path(opts));
-                       else if (match_stat_data(&todo_list->stat, &st)) {
+                       } else if (match_stat_data(&todo_list->stat, &st)) {
+                               /* Reread the todo file if it has changed. */
                                todo_list_release(todo_list);
-                               if (read_populate_todo(todo_list, opts))
+                               if (read_populate_todo(r, todo_list, opts))
                                        res = -1; /* message was printed */
                                /* `current` will be incremented below */
                                todo_list->current = -1;
                        }
-               } else if (!is_noop(item->command))
-                       return error(_("unknown command %d"), item->command);
+               }
 
                todo_list->current++;
                if (res)
@@ -2124,8 +3992,8 @@ cleanup_head_ref:
                        }
                        msg = reflog_message(opts, "finish", "%s onto %s",
                                head_ref.buf, buf.buf);
-                       if (update_ref(msg, head_ref.buf, head.hash, orig.hash,
-                                       REF_NODEREF, UPDATE_REFS_MSG_ON_ERR)) {
+                       if (update_ref(msg, head_ref.buf, &head, &orig,
+                                      REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR)) {
                                res = error(_("could not update %s"),
                                        head_ref.buf);
                                goto cleanup_head_ref;
@@ -2145,7 +4013,7 @@ cleanup_head_ref:
                        struct object_id orig, head;
 
                        memset(&log_tree_opt, 0, sizeof(log_tree_opt));
-                       init_revisions(&log_tree_opt, NULL);
+                       repo_init_revisions(r, &log_tree_opt, NULL);
                        log_tree_opt.diff = 1;
                        log_tree_opt.diffopt.output_format =
                                DIFF_FORMAT_DIFFSTAT;
@@ -2180,6 +4048,7 @@ cleanup_head_ref:
                                hook.in = open(rebase_path_rewritten_list(),
                                        O_RDONLY);
                                hook.stdout_to_stderr = 1;
+                               hook.trace2_hook_name = "post-rewrite";
                                argv_array_push(&hook.args, post_rewrite_hook);
                                argv_array_push(&hook.args, "rebase");
                                /* we don't care if this hook failed */
@@ -2188,8 +4057,13 @@ cleanup_head_ref:
                }
                apply_autostash(opts);
 
-               fprintf(stderr, "Successfully rebased and updated %s.\n",
-                       head_ref.buf);
+               if (!opts->quiet) {
+                       if (!opts->verbose)
+                               term_clear_line();
+                       fprintf(stderr,
+                               "Successfully rebased and updated %s.\n",
+                               head_ref.buf);
+               }
 
                strbuf_release(&buf);
                strbuf_release(&head_ref);
@@ -2202,29 +4076,27 @@ cleanup_head_ref:
        return sequencer_remove_state(opts);
 }
 
-static int continue_single_pick(void)
+static int continue_single_pick(struct repository *r)
 {
        const char *argv[] = { "commit", NULL };
 
-       if (!file_exists(git_path_cherry_pick_head()) &&
-           !file_exists(git_path_revert_head()))
+       if (!file_exists(git_path_cherry_pick_head(r)) &&
+           !file_exists(git_path_revert_head(r)))
                return error(_("no cherry-pick or revert in progress"));
        return run_command_v_opt(argv, RUN_GIT_CMD);
 }
 
-static int commit_staged_changes(struct replay_opts *opts)
+static int commit_staged_changes(struct repository *r,
+                                struct replay_opts *opts,
+                                struct todo_list *todo_list)
 {
        unsigned int flags = ALLOW_EMPTY | EDIT_MSG;
+       unsigned int final_fixup = 0, is_clean;
 
-       if (has_unstaged_changes(1))
+       if (has_unstaged_changes(r, 1))
                return error(_("cannot rebase: You have unstaged changes."));
-       if (!has_uncommitted_changes(0)) {
-               const char *cherry_pick_head = git_path_cherry_pick_head();
 
-               if (file_exists(cherry_pick_head) && unlink(cherry_pick_head))
-                       return error(_("could not remove CHERRY_PICK_HEAD"));
-               return 0;
-       }
+       is_clean = !has_uncommitted_changes(r, 0);
 
        if (file_exists(rebase_path_amend())) {
                struct strbuf rev = STRBUF_INIT;
@@ -2237,50 +4109,155 @@ static int commit_staged_changes(struct replay_opts *opts)
                if (get_oid_hex(rev.buf, &to_amend))
                        return error(_("invalid contents: '%s'"),
                                rebase_path_amend());
-               if (oidcmp(&head, &to_amend))
+               if (!is_clean && !oideq(&head, &to_amend))
                        return error(_("\nYou have uncommitted changes in your "
                                       "working tree. Please, commit them\n"
                                       "first and then run 'git rebase "
                                       "--continue' again."));
+               /*
+                * When skipping a failed fixup/squash, we need to edit the
+                * commit message, the current fixup list and count, and if it
+                * was the last fixup/squash in the chain, we need to clean up
+                * the commit message and if there was a squash, let the user
+                * edit it.
+                */
+               if (!is_clean || !opts->current_fixup_count)
+                       ; /* this is not the final fixup */
+               else if (!oideq(&head, &to_amend) ||
+                        !file_exists(rebase_path_stopped_sha())) {
+                       /* was a final fixup or squash done manually? */
+                       if (!is_fixup(peek_command(todo_list, 0))) {
+                               unlink(rebase_path_fixup_msg());
+                               unlink(rebase_path_squash_msg());
+                               unlink(rebase_path_current_fixups());
+                               strbuf_reset(&opts->current_fixups);
+                               opts->current_fixup_count = 0;
+                       }
+               } else {
+                       /* we are in a fixup/squash chain */
+                       const char *p = opts->current_fixups.buf;
+                       int len = opts->current_fixups.len;
+
+                       opts->current_fixup_count--;
+                       if (!len)
+                               BUG("Incorrect current_fixups:\n%s", p);
+                       while (len && p[len - 1] != '\n')
+                               len--;
+                       strbuf_setlen(&opts->current_fixups, len);
+                       if (write_message(p, len, rebase_path_current_fixups(),
+                                         0) < 0)
+                               return error(_("could not write file: '%s'"),
+                                            rebase_path_current_fixups());
+
+                       /*
+                        * If a fixup/squash in a fixup/squash chain failed, the
+                        * commit message is already correct, no need to commit
+                        * it again.
+                        *
+                        * Only if it is the final command in the fixup/squash
+                        * chain, and only if the chain is longer than a single
+                        * fixup/squash command (which was just skipped), do we
+                        * actually need to re-commit with a cleaned up commit
+                        * message.
+                        */
+                       if (opts->current_fixup_count > 0 &&
+                           !is_fixup(peek_command(todo_list, 0))) {
+                               final_fixup = 1;
+                               /*
+                                * If there was not a single "squash" in the
+                                * chain, we only need to clean up the commit
+                                * message, no need to bother the user with
+                                * opening the commit message in the editor.
+                                */
+                               if (!starts_with(p, "squash ") &&
+                                   !strstr(p, "\nsquash "))
+                                       flags = (flags & ~EDIT_MSG) | CLEANUP_MSG;
+                       } else if (is_fixup(peek_command(todo_list, 0))) {
+                               /*
+                                * We need to update the squash message to skip
+                                * the latest commit message.
+                                */
+                               struct commit *commit;
+                               const char *path = rebase_path_squash_msg();
+                               const char *encoding = get_commit_output_encoding();
+
+                               if (parse_head(r, &commit) ||
+                                   !(p = logmsg_reencode(commit, NULL, encoding)) ||
+                                   write_message(p, strlen(p), path, 0)) {
+                                       unuse_commit_buffer(commit, p);
+                                       return error(_("could not write file: "
+                                                      "'%s'"), path);
+                               }
+                               unuse_commit_buffer(commit, p);
+                       }
+               }
 
                strbuf_release(&rev);
                flags |= AMEND_MSG;
        }
 
-       if (run_git_commit(rebase_path_message(), opts, flags))
+       if (is_clean) {
+               const char *cherry_pick_head = git_path_cherry_pick_head(r);
+
+               if (file_exists(cherry_pick_head) && unlink(cherry_pick_head))
+                       return error(_("could not remove CHERRY_PICK_HEAD"));
+               if (!final_fixup)
+                       return 0;
+       }
+
+       if (run_git_commit(r, final_fixup ? NULL : rebase_path_message(),
+                          opts, flags))
                return error(_("could not commit staged changes."));
        unlink(rebase_path_amend());
+       unlink(git_path_merge_head(r));
+       if (final_fixup) {
+               unlink(rebase_path_fixup_msg());
+               unlink(rebase_path_squash_msg());
+       }
+       if (opts->current_fixup_count > 0) {
+               /*
+                * Whether final fixup or not, we just cleaned up the commit
+                * message...
+                */
+               unlink(rebase_path_current_fixups());
+               strbuf_reset(&opts->current_fixups);
+               opts->current_fixup_count = 0;
+       }
        return 0;
 }
 
-int sequencer_continue(struct replay_opts *opts)
+int sequencer_continue(struct repository *r, struct replay_opts *opts)
 {
        struct todo_list todo_list = TODO_LIST_INIT;
        int res;
 
-       if (read_and_refresh_cache(opts))
+       if (read_and_refresh_cache(r, opts))
                return -1;
 
-       if (is_rebase_i(opts)) {
-               if (commit_staged_changes(opts))
-                       return -1;
-       } else if (!file_exists(get_todo_path(opts)))
-               return continue_single_pick();
        if (read_populate_opts(opts))
                return -1;
-       if ((res = read_populate_todo(&todo_list, opts)))
+       if (is_rebase_i(opts)) {
+               if ((res = read_populate_todo(r, &todo_list, opts)))
+                       goto release_todo_list;
+               if (commit_staged_changes(r, opts, &todo_list)) {
+                       res = -1;
+                       goto release_todo_list;
+               }
+       } else if (!file_exists(get_todo_path(opts)))
+               return continue_single_pick(r);
+       else if ((res = read_populate_todo(r, &todo_list, opts)))
                goto release_todo_list;
 
        if (!is_rebase_i(opts)) {
                /* Verify that the conflict has been resolved */
-               if (file_exists(git_path_cherry_pick_head()) ||
-                   file_exists(git_path_revert_head())) {
-                       res = continue_single_pick();
+               if (file_exists(git_path_cherry_pick_head(r)) ||
+                   file_exists(git_path_revert_head(r))) {
+                       res = continue_single_pick(r);
                        if (res)
                                goto release_todo_list;
                }
-               if (index_differs_from("HEAD", 0, 0)) {
-                       res = error_dirty_index(opts);
+               if (index_differs_from(r, "HEAD", NULL, 0)) {
+                       res = error_dirty_index(r, opts);
                        goto release_todo_list;
                }
                todo_list.current++;
@@ -2294,27 +4271,33 @@ int sequencer_continue(struct replay_opts *opts)
                strbuf_release(&buf);
        }
 
-       res = pick_commits(&todo_list, opts);
+       res = pick_commits(r, &todo_list, opts);
 release_todo_list:
        todo_list_release(&todo_list);
        return res;
 }
 
-static int single_pick(struct commit *cmit, struct replay_opts *opts)
+static int single_pick(struct repository *r,
+                      struct commit *cmit,
+                      struct replay_opts *opts)
 {
+       int check_todo;
+
        setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
-       return do_pick_commit(opts->action == REPLAY_PICK ?
-               TODO_PICK : TODO_REVERT, cmit, opts, 0);
+       return do_pick_commit(r, opts->action == REPLAY_PICK ?
+                             TODO_PICK : TODO_REVERT, cmit, opts, 0,
+                             &check_todo);
 }
 
-int sequencer_pick_revisions(struct replay_opts *opts)
+int sequencer_pick_revisions(struct repository *r,
+                            struct replay_opts *opts)
 {
        struct todo_list todo_list = TODO_LIST_INIT;
        struct object_id oid;
        int i, res;
 
        assert(opts->revs);
-       if (read_and_refresh_cache(opts))
+       if (read_and_refresh_cache(r, opts))
                return -1;
 
        for (i = 0; i < opts->revs->pending.nr; i++) {
@@ -2326,10 +4309,12 @@ int sequencer_pick_revisions(struct replay_opts *opts)
                        continue;
 
                if (!get_oid(name, &oid)) {
-                       if (!lookup_commit_reference_gently(&oid, 1)) {
-                               enum object_type type = sha1_object_info(oid.hash, NULL);
+                       if (!lookup_commit_reference_gently(r, &oid, 1)) {
+                               enum object_type type = oid_object_info(r,
+                                                                       &oid,
+                                                                       NULL);
                                return error(_("%s: can't cherry-pick a %s"),
-                                       name, typename(type));
+                                       name, type_name(type));
                        }
                } else
                        return error(_("%s: bad revision"), name);
@@ -2350,9 +4335,11 @@ int sequencer_pick_revisions(struct replay_opts *opts)
                if (prepare_revision_walk(opts->revs))
                        return error(_("revision walk setup failed"));
                cmit = get_revision(opts->revs);
-               if (!cmit || get_revision(opts->revs))
-                       return error("BUG: expected exactly one commit from walk");
-               return single_pick(cmit, opts);
+               if (!cmit)
+                       return error(_("empty commit set passed"));
+               if (get_revision(opts->revs))
+                       BUG("unexpected extra commit from walk");
+               return single_pick(r, cmit, opts);
        }
 
        /*
@@ -2362,7 +4349,7 @@ int sequencer_pick_revisions(struct replay_opts *opts)
         */
 
        if (walk_revs_populate_todo(&todo_list, opts) ||
-                       create_seq_dir() < 0)
+                       create_seq_dir(r) < 0)
                return -1;
        if (get_oid("HEAD", &oid) && (opts->action == REPLAY_REVERT))
                return error(_("can't revert as initial commit"));
@@ -2371,20 +4358,19 @@ int sequencer_pick_revisions(struct replay_opts *opts)
        if (save_opts(opts))
                return -1;
        update_abort_safety_file();
-       res = pick_commits(&todo_list, opts);
+       res = pick_commits(r, &todo_list, opts);
        todo_list_release(&todo_list);
        return res;
 }
 
-void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
+void append_signoff(struct strbuf *msgbuf, size_t ignore_footer, unsigned flag)
 {
        unsigned no_dup_sob = flag & APPEND_SIGNOFF_DEDUP;
        struct strbuf sob = STRBUF_INIT;
        int has_footer;
 
        strbuf_addstr(&sob, sign_off_header);
-       strbuf_addstr(&sob, fmt_name(getenv("GIT_COMMITTER_NAME"),
-                               getenv("GIT_COMMITTER_EMAIL")));
+       strbuf_addstr(&sob, fmt_name(WANT_COMMITTER_IDENT));
        strbuf_addch(&sob, '\n');
 
        if (!ignore_footer)
@@ -2437,19 +4423,390 @@ void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
        strbuf_release(&sob);
 }
 
-int sequencer_make_script(int keep_empty, FILE *out,
-               int argc, const char **argv)
+struct labels_entry {
+       struct hashmap_entry entry;
+       char label[FLEX_ARRAY];
+};
+
+static int labels_cmp(const void *fndata, const struct hashmap_entry *eptr,
+                     const struct hashmap_entry *entry_or_key, const void *key)
+{
+       const struct labels_entry *a, *b;
+
+       a = container_of(eptr, const struct labels_entry, entry);
+       b = container_of(entry_or_key, const struct labels_entry, entry);
+
+       return key ? strcmp(a->label, key) : strcmp(a->label, b->label);
+}
+
+struct string_entry {
+       struct oidmap_entry entry;
+       char string[FLEX_ARRAY];
+};
+
+struct label_state {
+       struct oidmap commit2label;
+       struct hashmap labels;
+       struct strbuf buf;
+};
+
+static const char *label_oid(struct object_id *oid, const char *label,
+                            struct label_state *state)
+{
+       struct labels_entry *labels_entry;
+       struct string_entry *string_entry;
+       struct object_id dummy;
+       int i;
+
+       string_entry = oidmap_get(&state->commit2label, oid);
+       if (string_entry)
+               return string_entry->string;
+
+       /*
+        * For "uninteresting" commits, i.e. commits that are not to be
+        * rebased, and which can therefore not be labeled, we use a unique
+        * abbreviation of the commit name. This is slightly more complicated
+        * than calling find_unique_abbrev() because we also need to make
+        * sure that the abbreviation does not conflict with any other
+        * label.
+        *
+        * We disallow "interesting" commits to be labeled by a string that
+        * is a valid full-length hash, to ensure that we always can find an
+        * abbreviation for any uninteresting commit's names that does not
+        * clash with any other label.
+        */
+       strbuf_reset(&state->buf);
+       if (!label) {
+               char *p;
+
+               strbuf_grow(&state->buf, GIT_MAX_HEXSZ);
+               label = p = state->buf.buf;
+
+               find_unique_abbrev_r(p, oid, default_abbrev);
+
+               /*
+                * We may need to extend the abbreviated hash so that there is
+                * no conflicting label.
+                */
+               if (hashmap_get_from_hash(&state->labels, strihash(p), p)) {
+                       size_t i = strlen(p) + 1;
+
+                       oid_to_hex_r(p, oid);
+                       for (; i < the_hash_algo->hexsz; i++) {
+                               char save = p[i];
+                               p[i] = '\0';
+                               if (!hashmap_get_from_hash(&state->labels,
+                                                          strihash(p), p))
+                                       break;
+                               p[i] = save;
+                       }
+               }
+       } else {
+               struct strbuf *buf = &state->buf;
+
+               /*
+                * Sanitize labels by replacing non-alpha-numeric characters
+                * (including white-space ones) by dashes, as they might be
+                * illegal in file names (and hence in ref names).
+                *
+                * Note that we retain non-ASCII UTF-8 characters (identified
+                * via the most significant bit). They should be all acceptable
+                * in file names. We do not validate the UTF-8 here, that's not
+                * the job of this function.
+                */
+               for (; *label; label++)
+                       if ((*label & 0x80) || isalnum(*label))
+                               strbuf_addch(buf, *label);
+                       /* avoid leading dash and double-dashes */
+                       else if (buf->len && buf->buf[buf->len - 1] != '-')
+                               strbuf_addch(buf, '-');
+               if (!buf->len) {
+                       strbuf_addstr(buf, "rev-");
+                       strbuf_add_unique_abbrev(buf, oid, default_abbrev);
+               }
+               label = buf->buf;
+
+               if ((buf->len == the_hash_algo->hexsz &&
+                    !get_oid_hex(label, &dummy)) ||
+                   (buf->len == 1 && *label == '#') ||
+                   hashmap_get_from_hash(&state->labels,
+                                         strihash(label), label)) {
+                       /*
+                        * If the label already exists, or if the label is a
+                        * valid full OID, or the label is a '#' (which we use
+                        * as a separator between merge heads and oneline), we
+                        * append a dash and a number to make it unique.
+                        */
+                       size_t len = buf->len;
+
+                       for (i = 2; ; i++) {
+                               strbuf_setlen(buf, len);
+                               strbuf_addf(buf, "-%d", i);
+                               if (!hashmap_get_from_hash(&state->labels,
+                                                          strihash(buf->buf),
+                                                          buf->buf))
+                                       break;
+                       }
+
+                       label = buf->buf;
+               }
+       }
+
+       FLEX_ALLOC_STR(labels_entry, label, label);
+       hashmap_entry_init(&labels_entry->entry, strihash(label));
+       hashmap_add(&state->labels, &labels_entry->entry);
+
+       FLEX_ALLOC_STR(string_entry, string, label);
+       oidcpy(&string_entry->entry.oid, oid);
+       oidmap_put(&state->commit2label, string_entry);
+
+       return string_entry->string;
+}
+
+static int make_script_with_merges(struct pretty_print_context *pp,
+                                  struct rev_info *revs, struct strbuf *out,
+                                  unsigned flags)
+{
+       int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
+       int rebase_cousins = flags & TODO_LIST_REBASE_COUSINS;
+       int root_with_onto = flags & TODO_LIST_ROOT_WITH_ONTO;
+       struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT;
+       struct strbuf label = STRBUF_INIT;
+       struct commit_list *commits = NULL, **tail = &commits, *iter;
+       struct commit_list *tips = NULL, **tips_tail = &tips;
+       struct commit *commit;
+       struct oidmap commit2todo = OIDMAP_INIT;
+       struct string_entry *entry;
+       struct oidset interesting = OIDSET_INIT, child_seen = OIDSET_INIT,
+               shown = OIDSET_INIT;
+       struct label_state state = { OIDMAP_INIT, { NULL }, STRBUF_INIT };
+
+       int abbr = flags & TODO_LIST_ABBREVIATE_CMDS;
+       const char *cmd_pick = abbr ? "p" : "pick",
+               *cmd_label = abbr ? "l" : "label",
+               *cmd_reset = abbr ? "t" : "reset",
+               *cmd_merge = abbr ? "m" : "merge";
+
+       oidmap_init(&commit2todo, 0);
+       oidmap_init(&state.commit2label, 0);
+       hashmap_init(&state.labels, labels_cmp, NULL, 0);
+       strbuf_init(&state.buf, 32);
+
+       if (revs->cmdline.nr && (revs->cmdline.rev[0].flags & BOTTOM)) {
+               struct labels_entry *onto_label_entry;
+               struct object_id *oid = &revs->cmdline.rev[0].item->oid;
+               FLEX_ALLOC_STR(entry, string, "onto");
+               oidcpy(&entry->entry.oid, oid);
+               oidmap_put(&state.commit2label, entry);
+
+               FLEX_ALLOC_STR(onto_label_entry, label, "onto");
+               hashmap_entry_init(&onto_label_entry->entry, strihash("onto"));
+               hashmap_add(&state.labels, &onto_label_entry->entry);
+       }
+
+       /*
+        * First phase:
+        * - get onelines for all commits
+        * - gather all branch tips (i.e. 2nd or later parents of merges)
+        * - label all branch tips
+        */
+       while ((commit = get_revision(revs))) {
+               struct commit_list *to_merge;
+               const char *p1, *p2;
+               struct object_id *oid;
+               int is_empty;
+
+               tail = &commit_list_insert(commit, tail)->next;
+               oidset_insert(&interesting, &commit->object.oid);
+
+               is_empty = is_original_commit_empty(commit);
+               if (!is_empty && (commit->object.flags & PATCHSAME))
+                       continue;
+
+               strbuf_reset(&oneline);
+               pretty_print_commit(pp, commit, &oneline);
+
+               to_merge = commit->parents ? commit->parents->next : NULL;
+               if (!to_merge) {
+                       /* non-merge commit: easy case */
+                       strbuf_reset(&buf);
+                       if (!keep_empty && is_empty)
+                               strbuf_addf(&buf, "%c ", comment_line_char);
+                       strbuf_addf(&buf, "%s %s %s", cmd_pick,
+                                   oid_to_hex(&commit->object.oid),
+                                   oneline.buf);
+
+                       FLEX_ALLOC_STR(entry, string, buf.buf);
+                       oidcpy(&entry->entry.oid, &commit->object.oid);
+                       oidmap_put(&commit2todo, entry);
+
+                       continue;
+               }
+
+               /* Create a label */
+               strbuf_reset(&label);
+               if (skip_prefix(oneline.buf, "Merge ", &p1) &&
+                   (p1 = strchr(p1, '\'')) &&
+                   (p2 = strchr(++p1, '\'')))
+                       strbuf_add(&label, p1, p2 - p1);
+               else if (skip_prefix(oneline.buf, "Merge pull request ",
+                                    &p1) &&
+                        (p1 = strstr(p1, " from ")))
+                       strbuf_addstr(&label, p1 + strlen(" from "));
+               else
+                       strbuf_addbuf(&label, &oneline);
+
+               strbuf_reset(&buf);
+               strbuf_addf(&buf, "%s -C %s",
+                           cmd_merge, oid_to_hex(&commit->object.oid));
+
+               /* label the tips of merged branches */
+               for (; to_merge; to_merge = to_merge->next) {
+                       oid = &to_merge->item->object.oid;
+                       strbuf_addch(&buf, ' ');
+
+                       if (!oidset_contains(&interesting, oid)) {
+                               strbuf_addstr(&buf, label_oid(oid, NULL,
+                                                             &state));
+                               continue;
+                       }
+
+                       tips_tail = &commit_list_insert(to_merge->item,
+                                                       tips_tail)->next;
+
+                       strbuf_addstr(&buf, label_oid(oid, label.buf, &state));
+               }
+               strbuf_addf(&buf, " # %s", oneline.buf);
+
+               FLEX_ALLOC_STR(entry, string, buf.buf);
+               oidcpy(&entry->entry.oid, &commit->object.oid);
+               oidmap_put(&commit2todo, entry);
+       }
+
+       /*
+        * Second phase:
+        * - label branch points
+        * - add HEAD to the branch tips
+        */
+       for (iter = commits; iter; iter = iter->next) {
+               struct commit_list *parent = iter->item->parents;
+               for (; parent; parent = parent->next) {
+                       struct object_id *oid = &parent->item->object.oid;
+                       if (!oidset_contains(&interesting, oid))
+                               continue;
+                       if (oidset_insert(&child_seen, oid))
+                               label_oid(oid, "branch-point", &state);
+               }
+
+               /* Add HEAD as implicit "tip of branch" */
+               if (!iter->next)
+                       tips_tail = &commit_list_insert(iter->item,
+                                                       tips_tail)->next;
+       }
+
+       /*
+        * Third phase: output the todo list. This is a bit tricky, as we
+        * want to avoid jumping back and forth between revisions. To
+        * accomplish that goal, we walk backwards from the branch tips,
+        * gathering commits not yet shown, reversing the list on the fly,
+        * then outputting that list (labeling revisions as needed).
+        */
+       strbuf_addf(out, "%s onto\n", cmd_label);
+       for (iter = tips; iter; iter = iter->next) {
+               struct commit_list *list = NULL, *iter2;
+
+               commit = iter->item;
+               if (oidset_contains(&shown, &commit->object.oid))
+                       continue;
+               entry = oidmap_get(&state.commit2label, &commit->object.oid);
+
+               if (entry)
+                       strbuf_addf(out, "\n%c Branch %s\n", comment_line_char, entry->string);
+               else
+                       strbuf_addch(out, '\n');
+
+               while (oidset_contains(&interesting, &commit->object.oid) &&
+                      !oidset_contains(&shown, &commit->object.oid)) {
+                       commit_list_insert(commit, &list);
+                       if (!commit->parents) {
+                               commit = NULL;
+                               break;
+                       }
+                       commit = commit->parents->item;
+               }
+
+               if (!commit)
+                       strbuf_addf(out, "%s %s\n", cmd_reset,
+                                   rebase_cousins || root_with_onto ?
+                                   "onto" : "[new root]");
+               else {
+                       const char *to = NULL;
+
+                       entry = oidmap_get(&state.commit2label,
+                                          &commit->object.oid);
+                       if (entry)
+                               to = entry->string;
+                       else if (!rebase_cousins)
+                               to = label_oid(&commit->object.oid, NULL,
+                                              &state);
+
+                       if (!to || !strcmp(to, "onto"))
+                               strbuf_addf(out, "%s onto\n", cmd_reset);
+                       else {
+                               strbuf_reset(&oneline);
+                               pretty_print_commit(pp, commit, &oneline);
+                               strbuf_addf(out, "%s %s # %s\n",
+                                           cmd_reset, to, oneline.buf);
+                       }
+               }
+
+               for (iter2 = list; iter2; iter2 = iter2->next) {
+                       struct object_id *oid = &iter2->item->object.oid;
+                       entry = oidmap_get(&commit2todo, oid);
+                       /* only show if not already upstream */
+                       if (entry)
+                               strbuf_addf(out, "%s\n", entry->string);
+                       entry = oidmap_get(&state.commit2label, oid);
+                       if (entry)
+                               strbuf_addf(out, "%s %s\n",
+                                           cmd_label, entry->string);
+                       oidset_insert(&shown, oid);
+               }
+
+               free_commit_list(list);
+       }
+
+       free_commit_list(commits);
+       free_commit_list(tips);
+
+       strbuf_release(&label);
+       strbuf_release(&oneline);
+       strbuf_release(&buf);
+
+       oidmap_free(&commit2todo, 1);
+       oidmap_free(&state.commit2label, 1);
+       hashmap_free_entries(&state.labels, struct labels_entry, entry);
+       strbuf_release(&state.buf);
+
+       return 0;
+}
+
+int sequencer_make_script(struct repository *r, struct strbuf *out, int argc,
+                         const char **argv, unsigned flags)
 {
        char *format = NULL;
        struct pretty_print_context pp = {0};
-       struct strbuf buf = STRBUF_INIT;
        struct rev_info revs;
        struct commit *commit;
+       int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
+       const char *insn = flags & TODO_LIST_ABBREVIATE_CMDS ? "p" : "pick";
+       int rebase_merges = flags & TODO_LIST_REBASE_MERGES;
 
-       init_revisions(&revs, NULL);
+       repo_init_revisions(r, &revs, NULL);
        revs.verbose_header = 1;
-       revs.max_parents = 1;
-       revs.cherry_pick = 1;
+       if (!rebase_merges)
+               revs.max_parents = 1;
+       revs.cherry_mark = 1;
        revs.limited = 1;
        revs.reverse = 1;
        revs.right_only = 1;
@@ -2473,238 +4830,212 @@ int sequencer_make_script(int keep_empty, FILE *out,
        if (prepare_revision_walk(&revs) < 0)
                return error(_("make_script: error preparing revisions"));
 
+       if (rebase_merges)
+               return make_script_with_merges(&pp, &revs, out, flags);
+
        while ((commit = get_revision(&revs))) {
-               strbuf_reset(&buf);
-               if (!keep_empty && is_original_commit_empty(commit))
-                       strbuf_addf(&buf, "%c ", comment_line_char);
-               strbuf_addf(&buf, "pick %s ", oid_to_hex(&commit->object.oid));
-               pretty_print_commit(&pp, commit, &buf);
-               strbuf_addch(&buf, '\n');
-               fputs(buf.buf, out);
+               int is_empty  = is_original_commit_empty(commit);
+
+               if (!is_empty && (commit->object.flags & PATCHSAME))
+                       continue;
+               if (!keep_empty && is_empty)
+                       strbuf_addf(out, "%c ", comment_line_char);
+               strbuf_addf(out, "%s %s ", insn,
+                           oid_to_hex(&commit->object.oid));
+               pretty_print_commit(&pp, commit, out);
+               strbuf_addch(out, '\n');
        }
-       strbuf_release(&buf);
        return 0;
 }
 
-
-int transform_todo_ids(int shorten_ids)
+/*
+ * Add commands after pick and (series of) squash/fixup commands
+ * in the todo list.
+ */
+void todo_list_add_exec_commands(struct todo_list *todo_list,
+                                struct string_list *commands)
 {
-       const char *todo_file = rebase_path_todo();
-       struct todo_list todo_list = TODO_LIST_INIT;
-       int fd, res, i;
-       FILE *out;
+       struct strbuf *buf = &todo_list->buf;
+       size_t base_offset = buf->len;
+       int i, insert, nr = 0, alloc = 0;
+       struct todo_item *items = NULL, *base_items = NULL;
 
-       strbuf_reset(&todo_list.buf);
-       fd = open(todo_file, O_RDONLY);
-       if (fd < 0)
-               return error_errno(_("could not open '%s'"), todo_file);
-       if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
-               close(fd);
-               return error(_("could not read '%s'."), todo_file);
-       }
-       close(fd);
+       base_items = xcalloc(commands->nr, sizeof(struct todo_item));
+       for (i = 0; i < commands->nr; i++) {
+               size_t command_len = strlen(commands->items[i].string);
 
-       res = parse_insn_buffer(todo_list.buf.buf, &todo_list);
-       if (res) {
-               todo_list_release(&todo_list);
-               return error(_("unusable todo list: '%s'"), todo_file);
-       }
+               strbuf_addstr(buf, commands->items[i].string);
+               strbuf_addch(buf, '\n');
 
-       out = fopen(todo_file, "w");
-       if (!out) {
-               todo_list_release(&todo_list);
-               return error(_("unable to open '%s' for writing"), todo_file);
+               base_items[i].command = TODO_EXEC;
+               base_items[i].offset_in_buf = base_offset;
+               base_items[i].arg_offset = base_offset + strlen("exec ");
+               base_items[i].arg_len = command_len - strlen("exec ");
+
+               base_offset += command_len + 1;
        }
-       for (i = 0; i < todo_list.nr; i++) {
-               struct todo_item *item = todo_list.items + i;
-               int bol = item->offset_in_buf;
-               const char *p = todo_list.buf.buf + bol;
-               int eol = i + 1 < todo_list.nr ?
-                       todo_list.items[i + 1].offset_in_buf :
-                       todo_list.buf.len;
 
-               if (item->command >= TODO_EXEC && item->command != TODO_DROP)
-                       fwrite(p, eol - bol, 1, out);
-               else {
-                       const char *id = shorten_ids ?
-                               short_commit_name(item->commit) :
-                               oid_to_hex(&item->commit->object.oid);
-                       int len;
+       /*
+        * Insert <commands> after every pick. Here, fixup/squash chains
+        * are considered part of the pick, so we insert the commands *after*
+        * those chains if there are any.
+        *
+        * As we insert the exec commands immediately after rearranging
+        * any fixups and before the user edits the list, a fixup chain
+        * can never contain comments (any comments are empty picks that
+        * have been commented out because the user did not specify
+        * --keep-empty).  So, it is safe to insert an exec command
+        * without looking at the command following a comment.
+        */
+       insert = 0;
+       for (i = 0; i < todo_list->nr; i++) {
+               enum todo_command command = todo_list->items[i].command;
+               if (insert && !is_fixup(command)) {
+                       ALLOC_GROW(items, nr + commands->nr, alloc);
+                       COPY_ARRAY(items + nr, base_items, commands->nr);
+                       nr += commands->nr;
+
+                       insert = 0;
+               }
 
-                       p += strspn(p, " \t"); /* left-trim command */
-                       len = strcspn(p, " \t"); /* length of command */
+               ALLOC_GROW(items, nr + 1, alloc);
+               items[nr++] = todo_list->items[i];
 
-                       fprintf(out, "%.*s %s %.*s\n",
-                               len, p, id, item->arg_len, item->arg);
-               }
+               if (command == TODO_PICK || command == TODO_MERGE)
+                       insert = 1;
        }
-       fclose(out);
-       todo_list_release(&todo_list);
-       return 0;
-}
 
-enum check_level {
-       CHECK_IGNORE = 0, CHECK_WARN, CHECK_ERROR
-};
-
-static enum check_level get_missing_commit_check_level(void)
-{
-       const char *value;
+       /* insert or append final <commands> */
+       if (insert || nr == todo_list->nr) {
+               ALLOC_GROW(items, nr + commands->nr, alloc);
+               COPY_ARRAY(items + nr, base_items, commands->nr);
+               nr += commands->nr;
+       }
 
-       if (git_config_get_value("rebase.missingcommitscheck", &value) ||
-                       !strcasecmp("ignore", value))
-               return CHECK_IGNORE;
-       if (!strcasecmp("warn", value))
-               return CHECK_WARN;
-       if (!strcasecmp("error", value))
-               return CHECK_ERROR;
-       warning(_("unrecognized setting %s for option "
-                 "rebase.missingCommitsCheck. Ignoring."), value);
-       return CHECK_IGNORE;
+       free(base_items);
+       FREE_AND_NULL(todo_list->items);
+       todo_list->items = items;
+       todo_list->nr = nr;
+       todo_list->alloc = alloc;
 }
 
-/*
- * Check if the user dropped some commits by mistake
- * Behaviour determined by rebase.missingCommitsCheck.
- * Check if there is an unrecognized command or a
- * bad SHA-1 in a command.
- */
-int check_todo_list(void)
+static void todo_list_to_strbuf(struct repository *r, struct todo_list *todo_list,
+                               struct strbuf *buf, int num, unsigned flags)
 {
-       enum check_level check_level = get_missing_commit_check_level();
-       struct strbuf todo_file = STRBUF_INIT;
-       struct todo_list todo_list = TODO_LIST_INIT;
-       struct strbuf missing = STRBUF_INIT;
-       int advise_to_edit_todo = 0, res = 0, fd, i;
-
-       strbuf_addstr(&todo_file, rebase_path_todo());
-       fd = open(todo_file.buf, O_RDONLY);
-       if (fd < 0) {
-               res = error_errno(_("could not open '%s'"), todo_file.buf);
-               goto leave_check;
-       }
-       if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
-               close(fd);
-               res = error(_("could not read '%s'."), todo_file.buf);
-               goto leave_check;
-       }
-       close(fd);
-       advise_to_edit_todo = res =
-               parse_insn_buffer(todo_list.buf.buf, &todo_list);
+       struct todo_item *item;
+       int i, max = todo_list->nr;
 
-       if (res || check_level == CHECK_IGNORE)
-               goto leave_check;
+       if (num > 0 && num < max)
+               max = num;
 
-       /* Mark the commits in git-rebase-todo as seen */
-       for (i = 0; i < todo_list.nr; i++) {
-               struct commit *commit = todo_list.items[i].commit;
-               if (commit)
-                       commit->util = (void *)1;
-       }
+       for (item = todo_list->items, i = 0; i < max; i++, item++) {
+               /* if the item is not a command write it and continue */
+               if (item->command >= TODO_COMMENT) {
+                       strbuf_addf(buf, "%.*s\n", item->arg_len,
+                                   todo_item_get_arg(todo_list, item));
+                       continue;
+               }
 
-       todo_list_release(&todo_list);
-       strbuf_addstr(&todo_file, ".backup");
-       fd = open(todo_file.buf, O_RDONLY);
-       if (fd < 0) {
-               res = error_errno(_("could not open '%s'"), todo_file.buf);
-               goto leave_check;
-       }
-       if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
-               close(fd);
-               res = error(_("could not read '%s'."), todo_file.buf);
-               goto leave_check;
-       }
-       close(fd);
-       strbuf_release(&todo_file);
-       res = !!parse_insn_buffer(todo_list.buf.buf, &todo_list);
+               /* add command to the buffer */
+               if (flags & TODO_LIST_ABBREVIATE_CMDS)
+                       strbuf_addch(buf, command_to_char(item->command));
+               else
+                       strbuf_addstr(buf, command_to_string(item->command));
+
+               /* add commit id */
+               if (item->commit) {
+                       const char *oid = flags & TODO_LIST_SHORTEN_IDS ?
+                                         short_commit_name(item->commit) :
+                                         oid_to_hex(&item->commit->object.oid);
+
+                       if (item->command == TODO_MERGE) {
+                               if (item->flags & TODO_EDIT_MERGE_MSG)
+                                       strbuf_addstr(buf, " -c");
+                               else
+                                       strbuf_addstr(buf, " -C");
+                       }
 
-       /* Find commits in git-rebase-todo.backup yet unseen */
-       for (i = todo_list.nr - 1; i >= 0; i--) {
-               struct todo_item *item = todo_list.items + i;
-               struct commit *commit = item->commit;
-               if (commit && !commit->util) {
-                       strbuf_addf(&missing, " - %s %.*s\n",
-                                   short_commit_name(commit),
-                                   item->arg_len, item->arg);
-                       commit->util = (void *)1;
+                       strbuf_addf(buf, " %s", oid);
                }
+
+               /* add all the rest */
+               if (!item->arg_len)
+                       strbuf_addch(buf, '\n');
+               else
+                       strbuf_addf(buf, " %.*s\n", item->arg_len,
+                                   todo_item_get_arg(todo_list, item));
        }
+}
+
+int todo_list_write_to_file(struct repository *r, struct todo_list *todo_list,
+                           const char *file, const char *shortrevisions,
+                           const char *shortonto, int num, unsigned flags)
+{
+       int res;
+       struct strbuf buf = STRBUF_INIT;
 
-       /* Warn about missing commits */
-       if (!missing.len)
-               goto leave_check;
+       todo_list_to_strbuf(r, todo_list, &buf, num, flags);
+       if (flags & TODO_LIST_APPEND_TODO_HELP)
+               append_todo_help(flags & TODO_LIST_KEEP_EMPTY, count_commands(todo_list),
+                                shortrevisions, shortonto, &buf);
 
-       if (check_level == CHECK_ERROR)
-               advise_to_edit_todo = res = 1;
+       res = write_message(buf.buf, buf.len, file, 0);
+       strbuf_release(&buf);
 
-       fprintf(stderr,
-               _("Warning: some commits may have been dropped accidentally.\n"
-               "Dropped commits (newer to older):\n"));
+       return res;
+}
 
-       /* Make the list user-friendly and display */
-       fputs(missing.buf, stderr);
-       strbuf_release(&missing);
+static const char edit_todo_list_advice[] =
+N_("You can fix this with 'git rebase --edit-todo' "
+"and then run 'git rebase --continue'.\n"
+"Or you can abort the rebase with 'git rebase"
+" --abort'.\n");
 
-       fprintf(stderr, _("To avoid this message, use \"drop\" to "
-               "explicitly remove a commit.\n\n"
-               "Use 'git config rebase.missingCommitsCheck' to change "
-               "the level of warnings.\n"
-               "The possible behaviours are: ignore, warn, error.\n\n"));
+int check_todo_list_from_file(struct repository *r)
+{
+       struct todo_list old_todo = TODO_LIST_INIT, new_todo = TODO_LIST_INIT;
+       int res = 0;
 
-leave_check:
-       strbuf_release(&todo_file);
-       todo_list_release(&todo_list);
+       if (strbuf_read_file_or_whine(&new_todo.buf, rebase_path_todo()) < 0) {
+               res = -1;
+               goto out;
+       }
 
-       if (advise_to_edit_todo)
-               fprintf(stderr,
-                       _("You can fix this with 'git rebase --edit-todo' "
-                         "and then run 'git rebase --continue'.\n"
-                         "Or you can abort the rebase with 'git rebase"
-                         " --abort'.\n"));
+       if (strbuf_read_file_or_whine(&old_todo.buf, rebase_path_todo_backup()) < 0) {
+               res = -1;
+               goto out;
+       }
+
+       res = todo_list_parse_insn_buffer(r, old_todo.buf.buf, &old_todo);
+       if (!res)
+               res = todo_list_parse_insn_buffer(r, new_todo.buf.buf, &new_todo);
+       if (!res)
+               res = todo_list_check(&old_todo, &new_todo);
+       if (res)
+               fprintf(stderr, _(edit_todo_list_advice));
+out:
+       todo_list_release(&old_todo);
+       todo_list_release(&new_todo);
 
        return res;
 }
 
 /* skip picking commits whose parents are unchanged */
-int skip_unnecessary_picks(void)
+static int skip_unnecessary_picks(struct repository *r,
+                                 struct todo_list *todo_list,
+                                 struct object_id *base_oid)
 {
-       const char *todo_file = rebase_path_todo();
-       struct strbuf buf = STRBUF_INIT;
-       struct todo_list todo_list = TODO_LIST_INIT;
-       struct object_id onto_oid, *oid = &onto_oid, *parent_oid;
-       int fd, i;
-
-       if (!read_oneliner(&buf, rebase_path_onto(), 0))
-               return error(_("could not read 'onto'"));
-       if (get_oid(buf.buf, &onto_oid)) {
-               strbuf_release(&buf);
-               return error(_("need a HEAD to fixup"));
-       }
-       strbuf_release(&buf);
-
-       fd = open(todo_file, O_RDONLY);
-       if (fd < 0) {
-               return error_errno(_("could not open '%s'"), todo_file);
-       }
-       if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
-               close(fd);
-               return error(_("could not read '%s'."), todo_file);
-       }
-       close(fd);
-       if (parse_insn_buffer(todo_list.buf.buf, &todo_list) < 0) {
-               todo_list_release(&todo_list);
-               return -1;
-       }
+       struct object_id *parent_oid;
+       int i;
 
-       for (i = 0; i < todo_list.nr; i++) {
-               struct todo_item *item = todo_list.items + i;
+       for (i = 0; i < todo_list->nr; i++) {
+               struct todo_item *item = todo_list->items + i;
 
                if (item->command >= TODO_NOOP)
                        continue;
                if (item->command != TODO_PICK)
                        break;
                if (parse_commit(item->commit)) {
-                       todo_list_release(&todo_list);
                        return error(_("could not parse commit '%s'"),
                                oid_to_hex(&item->commit->object.oid));
                }
@@ -2713,65 +5044,127 @@ int skip_unnecessary_picks(void)
                if (item->commit->parents->next)
                        break; /* merge commit */
                parent_oid = &item->commit->parents->item->object.oid;
-               if (hashcmp(parent_oid->hash, oid->hash))
+               if (!oideq(parent_oid, base_oid))
                        break;
-               oid = &item->commit->object.oid;
+               oidcpy(base_oid, &item->commit->object.oid);
        }
        if (i > 0) {
-               int offset = i < todo_list.nr ?
-                       todo_list.items[i].offset_in_buf : todo_list.buf.len;
                const char *done_path = rebase_path_done();
 
-               fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
-               if (fd < 0) {
-                       error_errno(_("could not open '%s' for writing"),
-                                   done_path);
-                       todo_list_release(&todo_list);
-                       return -1;
-               }
-               if (write_in_full(fd, todo_list.buf.buf, offset) < 0) {
+               if (todo_list_write_to_file(r, todo_list, done_path, NULL, NULL, i, 0)) {
                        error_errno(_("could not write to '%s'"), done_path);
-                       todo_list_release(&todo_list);
-                       close(fd);
                        return -1;
                }
-               close(fd);
 
-               fd = open(rebase_path_todo(), O_WRONLY, 0666);
-               if (fd < 0) {
-                       error_errno(_("could not open '%s' for writing"),
-                                   rebase_path_todo());
-                       todo_list_release(&todo_list);
-                       return -1;
-               }
-               if (write_in_full(fd, todo_list.buf.buf + offset,
-                               todo_list.buf.len - offset) < 0) {
-                       error_errno(_("could not write to '%s'"),
-                                   rebase_path_todo());
-                       close(fd);
-                       todo_list_release(&todo_list);
-                       return -1;
-               }
-               if (ftruncate(fd, todo_list.buf.len - offset) < 0) {
-                       error_errno(_("could not truncate '%s'"),
-                                   rebase_path_todo());
-                       todo_list_release(&todo_list);
-                       close(fd);
-                       return -1;
-               }
-               close(fd);
+               MOVE_ARRAY(todo_list->items, todo_list->items + i, todo_list->nr - i);
+               todo_list->nr -= i;
+               todo_list->current = 0;
+               todo_list->done_nr += i;
 
-               todo_list.current = i;
-               if (is_fixup(peek_command(&todo_list, 0)))
-                       record_in_rewritten(oid, peek_command(&todo_list, 0));
+               if (is_fixup(peek_command(todo_list, 0)))
+                       record_in_rewritten(base_oid, peek_command(todo_list, 0));
        }
 
-       todo_list_release(&todo_list);
-       printf("%s\n", oid_to_hex(oid));
-
        return 0;
 }
 
+int complete_action(struct repository *r, struct replay_opts *opts, unsigned flags,
+                   const char *shortrevisions, const char *onto_name,
+                   struct commit *onto, const char *orig_head,
+                   struct string_list *commands, unsigned autosquash,
+                   struct todo_list *todo_list)
+{
+       const char *shortonto, *todo_file = rebase_path_todo();
+       struct todo_list new_todo = TODO_LIST_INIT;
+       struct strbuf *buf = &todo_list->buf, buf2 = STRBUF_INIT;
+       struct object_id oid = onto->object.oid;
+       int res;
+
+       shortonto = find_unique_abbrev(&oid, DEFAULT_ABBREV);
+
+       if (buf->len == 0) {
+               struct todo_item *item = append_new_todo(todo_list);
+               item->command = TODO_NOOP;
+               item->commit = NULL;
+               item->arg_len = item->arg_offset = item->flags = item->offset_in_buf = 0;
+       }
+
+       if (autosquash && todo_list_rearrange_squash(todo_list))
+               return -1;
+
+       if (commands->nr)
+               todo_list_add_exec_commands(todo_list, commands);
+
+       if (count_commands(todo_list) == 0) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+
+               return error(_("nothing to do"));
+       }
+
+       res = edit_todo_list(r, todo_list, &new_todo, shortrevisions,
+                            shortonto, flags);
+       if (res == -1)
+               return -1;
+       else if (res == -2) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+
+               return -1;
+       } else if (res == -3) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+               todo_list_release(&new_todo);
+
+               return error(_("nothing to do"));
+       }
+
+       if (todo_list_parse_insn_buffer(r, new_todo.buf.buf, &new_todo) ||
+           todo_list_check(todo_list, &new_todo)) {
+               fprintf(stderr, _(edit_todo_list_advice));
+               checkout_onto(r, opts, onto_name, &onto->object.oid, orig_head);
+               todo_list_release(&new_todo);
+
+               return -1;
+       }
+
+       /* Expand the commit IDs */
+       todo_list_to_strbuf(r, &new_todo, &buf2, -1, 0);
+       strbuf_swap(&new_todo.buf, &buf2);
+       strbuf_release(&buf2);
+       new_todo.total_nr -= new_todo.nr;
+       if (todo_list_parse_insn_buffer(r, new_todo.buf.buf, &new_todo) < 0)
+               BUG("invalid todo list after expanding IDs:\n%s",
+                   new_todo.buf.buf);
+
+       if (opts->allow_ff && skip_unnecessary_picks(r, &new_todo, &oid)) {
+               todo_list_release(&new_todo);
+               return error(_("could not skip unnecessary pick commands"));
+       }
+
+       if (todo_list_write_to_file(r, &new_todo, todo_file, NULL, NULL, -1,
+                                   flags & ~(TODO_LIST_SHORTEN_IDS))) {
+               todo_list_release(&new_todo);
+               return error_errno(_("could not write '%s'"), todo_file);
+       }
+
+       res = -1;
+
+       if (checkout_onto(r, opts, onto_name, &oid, orig_head))
+               goto cleanup;
+
+       if (require_clean_work_tree(r, "rebase", "", 1, 1))
+               goto cleanup;
+
+       todo_list_write_total_nr(&new_todo);
+       res = pick_commits(r, &new_todo, opts);
+
+cleanup:
+       todo_list_release(&new_todo);
+
+       return res;
+}
+
 struct subject2item_entry {
        struct hashmap_entry entry;
        int i;
@@ -2779,12 +5172,20 @@ struct subject2item_entry {
 };
 
 static int subject2item_cmp(const void *fndata,
-                           const struct subject2item_entry *a,
-                           const struct subject2item_entry *b, const void *key)
+                           const struct hashmap_entry *eptr,
+                           const struct hashmap_entry *entry_or_key,
+                           const void *key)
 {
+       const struct subject2item_entry *a, *b;
+
+       a = container_of(eptr, const struct subject2item_entry, entry);
+       b = container_of(entry_or_key, const struct subject2item_entry, entry);
+
        return key ? strcmp(a->subject, key) : strcmp(a->subject, b->subject);
 }
 
+define_commit_slab(commit_todo_item, struct todo_item *);
+
 /*
  * Rearrange the todo list that has both "pick commit-id msg" and "pick
  * commit-id fixup!/squash! msg" in it so that the latter is put immediately
@@ -2794,27 +5195,15 @@ static int subject2item_cmp(const void *fndata,
  * message will have to be retrieved from the commit (as the oneline in the
  * script cannot be trusted) in order to normalize the autosquash arrangement.
  */
-int rearrange_squash(void)
+int todo_list_rearrange_squash(struct todo_list *todo_list)
 {
-       const char *todo_file = rebase_path_todo();
-       struct todo_list todo_list = TODO_LIST_INIT;
        struct hashmap subject2item;
-       int res = 0, rearranged = 0, *next, *tail, fd, i;
+       int rearranged = 0, *next, *tail, i, nr = 0, alloc = 0;
        char **subjects;
+       struct commit_todo_item commit_todo;
+       struct todo_item *items = NULL;
 
-       fd = open(todo_file, O_RDONLY);
-       if (fd < 0)
-               return error_errno(_("could not open '%s'"), todo_file);
-       if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
-               close(fd);
-               return error(_("could not read '%s'."), todo_file);
-       }
-       close(fd);
-       if (parse_insn_buffer(todo_list.buf.buf, &todo_list) < 0) {
-               todo_list_release(&todo_list);
-               return -1;
-       }
-
+       init_commit_todo_item(&commit_todo);
        /*
         * The hashmap maps onelines to the respective todo list index.
         *
@@ -2824,34 +5213,33 @@ int rearrange_squash(void)
         * In that case, last[i] will indicate the index of the latest item to
         * be moved to appear after the i'th.
         */
-       hashmap_init(&subject2item, (hashmap_cmp_fn) subject2item_cmp,
-                    NULL, todo_list.nr);
-       ALLOC_ARRAY(next, todo_list.nr);
-       ALLOC_ARRAY(tail, todo_list.nr);
-       ALLOC_ARRAY(subjects, todo_list.nr);
-       for (i = 0; i < todo_list.nr; i++) {
+       hashmap_init(&subject2item, subject2item_cmp, NULL, todo_list->nr);
+       ALLOC_ARRAY(next, todo_list->nr);
+       ALLOC_ARRAY(tail, todo_list->nr);
+       ALLOC_ARRAY(subjects, todo_list->nr);
+       for (i = 0; i < todo_list->nr; i++) {
                struct strbuf buf = STRBUF_INIT;
-               struct todo_item *item = todo_list.items + i;
+               struct todo_item *item = todo_list->items + i;
                const char *commit_buffer, *subject, *p;
                size_t subject_len;
                int i2 = -1;
                struct subject2item_entry *entry;
 
                next[i] = tail[i] = -1;
-               if (item->command >= TODO_EXEC) {
+               if (!item->commit || item->command == TODO_DROP) {
                        subjects[i] = NULL;
                        continue;
                }
 
                if (is_fixup(item->command)) {
-                       todo_list_release(&todo_list);
+                       clear_commit_todo_item(&commit_todo);
                        return error(_("the script was already rearranged."));
                }
 
-               item->commit->util = item;
+               *commit_todo_item_at(&commit_todo, item->commit) = item;
 
                parse_commit(item->commit);
-               commit_buffer = get_commit_buffer(item->commit, NULL);
+               commit_buffer = logmsg_reencode(item->commit, NULL, "UTF-8");
                find_commit_subject(commit_buffer, &subject);
                format_subject(&buf, subject, " ");
                subject = subjects[i] = strbuf_detach(&buf, &subject_len);
@@ -2868,17 +5256,20 @@ int rearrange_squash(void)
                                        break;
                        }
 
-                       if ((entry = hashmap_get_from_hash(&subject2item,
-                                                          strhash(p), p)))
+                       entry = hashmap_get_entry_from_hash(&subject2item,
+                                               strhash(p), p,
+                                               struct subject2item_entry,
+                                               entry);
+                       if (entry)
                                /* found by title */
                                i2 = entry->i;
                        else if (!strchr(p, ' ') &&
                                 (commit2 =
                                  lookup_commit_reference_by_name(p)) &&
-                                commit2->util)
+                                *commit_todo_item_at(&commit_todo, commit2))
                                /* found by commit name */
-                               i2 = (struct todo_item *)commit2->util
-                                       - todo_list.items;
+                               i2 = *commit_todo_item_at(&commit_todo, commit2)
+                                       - todo_list->items;
                        else {
                                /* copy can be a prefix of the commit subject */
                                for (i2 = 0; i2 < i; i2++)
@@ -2891,7 +5282,7 @@ int rearrange_squash(void)
                }
                if (i2 >= 0) {
                        rearranged = 1;
-                       todo_list.items[i].command =
+                       todo_list->items[i].command =
                                starts_with(subject, "fixup!") ?
                                TODO_FIXUP : TODO_SQUASH;
                        if (next[i2] < 0)
@@ -2903,16 +5294,15 @@ int rearrange_squash(void)
                                                strhash(subject), subject)) {
                        FLEX_ALLOC_MEM(entry, subject, subject, subject_len);
                        entry->i = i;
-                       hashmap_entry_init(entry, strhash(entry->subject));
-                       hashmap_put(&subject2item, entry);
+                       hashmap_entry_init(&entry->entry,
+                                       strhash(entry->subject));
+                       hashmap_put(&subject2item, &entry->entry);
                }
        }
 
        if (rearranged) {
-               struct strbuf buf = STRBUF_INIT;
-
-               for (i = 0; i < todo_list.nr; i++) {
-                       enum todo_command command = todo_list.items[i].command;
+               for (i = 0; i < todo_list->nr; i++) {
+                       enum todo_command command = todo_list->items[i].command;
                        int cur = i;
 
                        /*
@@ -2923,46 +5313,26 @@ int rearrange_squash(void)
                                continue;
 
                        while (cur >= 0) {
-                               int offset = todo_list.items[cur].offset_in_buf;
-                               int end_offset = cur + 1 < todo_list.nr ?
-                                       todo_list.items[cur + 1].offset_in_buf :
-                                       todo_list.buf.len;
-                               char *bol = todo_list.buf.buf + offset;
-                               char *eol = todo_list.buf.buf + end_offset;
-
-                               /* replace 'pick', by 'fixup' or 'squash' */
-                               command = todo_list.items[cur].command;
-                               if (is_fixup(command)) {
-                                       strbuf_addstr(&buf,
-                                               todo_command_info[command].str);
-                                       bol += strcspn(bol, " \t");
-                               }
-
-                               strbuf_add(&buf, bol, eol - bol);
-
+                               ALLOC_GROW(items, nr + 1, alloc);
+                               items[nr++] = todo_list->items[cur];
                                cur = next[cur];
                        }
                }
 
-               fd = open(todo_file, O_WRONLY);
-               if (fd < 0)
-                       res = error_errno(_("could not open '%s'"), todo_file);
-               else if (write(fd, buf.buf, buf.len) < 0)
-                       res = error_errno(_("could not write to '%s'"), todo_file);
-               else if (ftruncate(fd, buf.len) < 0)
-                       res = error_errno(_("could not truncate '%s'"),
-                                          todo_file);
-               close(fd);
-               strbuf_release(&buf);
+               FREE_AND_NULL(todo_list->items);
+               todo_list->items = items;
+               todo_list->nr = nr;
+               todo_list->alloc = alloc;
        }
 
        free(next);
        free(tail);
-       for (i = 0; i < todo_list.nr; i++)
+       for (i = 0; i < todo_list->nr; i++)
                free(subjects[i]);
        free(subjects);
-       hashmap_free(&subject2item, 1);
-       todo_list_release(&todo_list);
+       hashmap_free_entries(&subject2item, struct subject2item_entry, entry);
 
-       return res;
+       clear_commit_todo_item(&commit_todo);
+
+       return 0;
 }