Imported Upstream version 2.30.0
[platform/upstream/git.git] / refs.c
diff --git a/refs.c b/refs.c
index 9a318c8..13dc2c3 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -9,13 +9,15 @@
 #include "iterator.h"
 #include "refs.h"
 #include "refs/refs-internal.h"
+#include "run-command.h"
 #include "object-store.h"
 #include "object.h"
 #include "tag.h"
 #include "submodule.h"
 #include "worktree.h"
-#include "argv-array.h"
+#include "strvec.h"
 #include "repository.h"
+#include "sigchain.h"
 
 /*
  * List of all available backends
@@ -63,7 +65,7 @@ static unsigned char refname_disposition[256] = {
  * not legal.  It is legal if it is something reasonable to have under
  * ".git/refs/"; We do not like it if:
  *
- * - any path component of it begins with ".", or
+ * - it begins with ".", or
  * - it has double dots "..", or
  * - it has ASCII control characters, or
  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
@@ -71,31 +73,63 @@ static unsigned char refname_disposition[256] = {
  * - it ends with a "/", or
  * - it ends with ".lock", or
  * - it contains a "@{" portion
+ *
+ * When sanitized is not NULL, instead of rejecting the input refname
+ * as an error, try to come up with a usable replacement for the input
+ * refname in it.
  */
-static int check_refname_component(const char *refname, int *flags)
+static int check_refname_component(const char *refname, int *flags,
+                                  struct strbuf *sanitized)
 {
        const char *cp;
        char last = '\0';
+       size_t component_start = 0; /* garbage - not a reasonable initial value */
+
+       if (sanitized)
+               component_start = sanitized->len;
 
        for (cp = refname; ; cp++) {
                int ch = *cp & 255;
                unsigned char disp = refname_disposition[ch];
+
+               if (sanitized && disp != 1)
+                       strbuf_addch(sanitized, ch);
+
                switch (disp) {
                case 1:
                        goto out;
                case 2:
-                       if (last == '.')
-                               return -1; /* Refname contains "..". */
+                       if (last == '.') { /* Refname contains "..". */
+                               if (sanitized)
+                                       /* collapse ".." to single "." */
+                                       strbuf_setlen(sanitized, sanitized->len - 1);
+                               else
+                                       return -1;
+                       }
                        break;
                case 3:
-                       if (last == '@')
-                               return -1; /* Refname contains "@{". */
+                       if (last == '@') { /* Refname contains "@{". */
+                               if (sanitized)
+                                       sanitized->buf[sanitized->len-1] = '-';
+                               else
+                                       return -1;
+                       }
                        break;
                case 4:
-                       return -1;
+                       /* forbidden char */
+                       if (sanitized)
+                               sanitized->buf[sanitized->len-1] = '-';
+                       else
+                               return -1;
+                       break;
                case 5:
-                       if (!(*flags & REFNAME_REFSPEC_PATTERN))
-                               return -1; /* refspec can't be a pattern */
+                       if (!(*flags & REFNAME_REFSPEC_PATTERN)) {
+                               /* refspec can't be a pattern */
+                               if (sanitized)
+                                       sanitized->buf[sanitized->len-1] = '-';
+                               else
+                                       return -1;
+                       }
 
                        /*
                         * Unset the pattern flag so that we only accept
@@ -109,26 +143,48 @@ static int check_refname_component(const char *refname, int *flags)
 out:
        if (cp == refname)
                return 0; /* Component has zero length. */
-       if (refname[0] == '.')
-               return -1; /* Component starts with '.'. */
+
+       if (refname[0] == '.') { /* Component starts with '.'. */
+               if (sanitized)
+                       sanitized->buf[component_start] = '-';
+               else
+                       return -1;
+       }
        if (cp - refname >= LOCK_SUFFIX_LEN &&
-           !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
-               return -1; /* Refname ends with ".lock". */
+           !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN)) {
+               if (!sanitized)
+                       return -1;
+               /* Refname ends with ".lock". */
+               while (strbuf_strip_suffix(sanitized, LOCK_SUFFIX)) {
+                       /* try again in case we have .lock.lock */
+               }
+       }
        return cp - refname;
 }
 
-int check_refname_format(const char *refname, int flags)
+static int check_or_sanitize_refname(const char *refname, int flags,
+                                    struct strbuf *sanitized)
 {
        int component_len, component_count = 0;
 
-       if (!strcmp(refname, "@"))
+       if (!strcmp(refname, "@")) {
                /* Refname is a single character '@'. */
-               return -1;
+               if (sanitized)
+                       strbuf_addch(sanitized, '-');
+               else
+                       return -1;
+       }
 
        while (1) {
+               if (sanitized && sanitized->len)
+                       strbuf_complete(sanitized, '/');
+
                /* We are at the start of a path component. */
-               component_len = check_refname_component(refname, &flags);
-               if (component_len <= 0)
+               component_len = check_refname_component(refname, &flags,
+                                                       sanitized);
+               if (sanitized && component_len == 0)
+                       ; /* OK, omit empty component */
+               else if (component_len <= 0)
                        return -1;
 
                component_count++;
@@ -138,13 +194,29 @@ int check_refname_format(const char *refname, int flags)
                refname += component_len + 1;
        }
 
-       if (refname[component_len - 1] == '.')
-               return -1; /* Refname ends with '.'. */
+       if (refname[component_len - 1] == '.') {
+               /* Refname ends with '.'. */
+               if (sanitized)
+                       ; /* omit ending dot */
+               else
+                       return -1;
+       }
        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
                return -1; /* Refname has only one component. */
        return 0;
 }
 
+int check_refname_format(const char *refname, int flags)
+{
+       return check_or_sanitize_refname(refname, flags, NULL);
+}
+
+void sanitize_refname_component(const char *refname, struct strbuf *out)
+{
+       if (check_or_sanitize_refname(refname, REFNAME_ALLOW_ONELEVEL, out))
+               BUG("sanitizing refname '%s' check returned error", refname);
+}
+
 int refname_is_safe(const char *refname)
 {
        const char *rest;
@@ -188,7 +260,7 @@ int ref_resolves_to_object(const char *refname,
 {
        if (flags & REF_ISBROKEN)
                return 0;
-       if (!has_sha1_file(oid->hash)) {
+       if (!has_object_file(oid)) {
                error(_("%s does not point to a valid object!"), refname);
                return 0;
        }
@@ -217,6 +289,7 @@ char *resolve_refdup(const char *refname, int resolve_flags,
 /* The argument to filter_refs */
 struct ref_filter {
        const char *pattern;
+       const char *prefix;
        each_ref_fn *fn;
        void *cb_data;
 };
@@ -240,53 +313,14 @@ int read_ref(const char *refname, struct object_id *oid)
        return read_ref_full(refname, RESOLVE_REF_READING, oid, NULL);
 }
 
-int ref_exists(const char *refname)
+int refs_ref_exists(struct ref_store *refs, const char *refname)
 {
-       return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, NULL, NULL);
-}
-
-static int match_ref_pattern(const char *refname,
-                            const struct string_list_item *item)
-{
-       int matched = 0;
-       if (item->util == NULL) {
-               if (!wildmatch(item->string, refname, 0))
-                       matched = 1;
-       } else {
-               const char *rest;
-               if (skip_prefix(refname, item->string, &rest) &&
-                   (!*rest || *rest == '/'))
-                       matched = 1;
-       }
-       return matched;
+       return !!refs_resolve_ref_unsafe(refs, refname, RESOLVE_REF_READING, NULL, NULL);
 }
 
-int ref_filter_match(const char *refname,
-                    const struct string_list *include_patterns,
-                    const struct string_list *exclude_patterns)
+int ref_exists(const char *refname)
 {
-       struct string_list_item *item;
-
-       if (exclude_patterns && exclude_patterns->nr) {
-               for_each_string_list_item(item, exclude_patterns) {
-                       if (match_ref_pattern(refname, item))
-                               return 0;
-               }
-       }
-
-       if (include_patterns && include_patterns->nr) {
-               int found = 0;
-               for_each_string_list_item(item, include_patterns) {
-                       if (match_ref_pattern(refname, item)) {
-                               found = 1;
-                               break;
-                       }
-               }
-
-               if (!found)
-                       return 0;
-       }
-       return 1;
+       return refs_ref_exists(get_main_ref_store(the_repository), refname);
 }
 
 static int filter_refs(const char *refname, const struct object_id *oid,
@@ -296,16 +330,18 @@ static int filter_refs(const char *refname, const struct object_id *oid,
 
        if (wildmatch(filter->pattern, refname, 0))
                return 0;
+       if (filter->prefix)
+               skip_prefix(refname, filter->prefix, &refname);
        return filter->fn(refname, oid, flags, filter->cb_data);
 }
 
 enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
 {
-       struct object *o = lookup_unknown_object(name->hash);
+       struct object *o = lookup_unknown_object(name);
 
        if (o->type == OBJ_NONE) {
                int type = oid_object_info(the_repository, name, NULL);
-               if (type < 0 || !object_as_type(the_repository, o, type, 0))
+               if (type < 0 || !object_as_type(o, type, 0))
                        return PEEL_INVALID;
        }
 
@@ -458,6 +494,7 @@ int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
        }
 
        filter.pattern = real_pattern.buf;
+       filter.prefix = prefix;
        filter.fn = fn;
        filter.cb_data = cb_data;
        ret = for_each_ref(filter_refs, &filter);
@@ -516,13 +553,62 @@ int refname_match(const char *abbrev_name, const char *full_name)
  * Given a 'prefix' expand it by the rules in 'ref_rev_parse_rules' and add
  * the results to 'prefixes'
  */
-void expand_ref_prefix(struct argv_array *prefixes, const char *prefix)
+void expand_ref_prefix(struct strvec *prefixes, const char *prefix)
 {
        const char **p;
        int len = strlen(prefix);
 
        for (p = ref_rev_parse_rules; *p; p++)
-               argv_array_pushf(prefixes, *p, len, prefix);
+               strvec_pushf(prefixes, *p, len, prefix);
+}
+
+static const char default_branch_name_advice[] = N_(
+"Using '%s' as the name for the initial branch. This default branch name\n"
+"is subject to change. To configure the initial branch name to use in all\n"
+"of your new repositories, which will suppress this warning, call:\n"
+"\n"
+"\tgit config --global init.defaultBranch <name>\n"
+"\n"
+"Names commonly chosen instead of 'master' are 'main', 'trunk' and\n"
+"'development'. The just-created branch can be renamed via this command:\n"
+"\n"
+"\tgit branch -m <name>\n"
+);
+
+char *repo_default_branch_name(struct repository *r, int quiet)
+{
+       const char *config_key = "init.defaultbranch";
+       const char *config_display_key = "init.defaultBranch";
+       char *ret = NULL, *full_ref;
+       const char *env = getenv("GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME");
+
+       if (env && *env)
+               ret = xstrdup(env);
+       else if (repo_config_get_string(r, config_key, &ret) < 0)
+               die(_("could not retrieve `%s`"), config_display_key);
+
+       if (!ret) {
+               ret = xstrdup("master");
+               if (!quiet)
+                       advise(_(default_branch_name_advice), ret);
+       }
+
+       full_ref = xstrfmt("refs/heads/%s", ret);
+       if (check_refname_format(full_ref, 0))
+               die(_("invalid branch name: %s = %s"), config_display_key, ret);
+       free(full_ref);
+
+       return ret;
+}
+
+const char *git_default_branch_name(int quiet)
+{
+       static char *ret;
+
+       if (!ret)
+               ret = repo_default_branch_name(the_repository, quiet);
+
+       return ret;
 }
 
 /*
@@ -530,10 +616,15 @@ void expand_ref_prefix(struct argv_array *prefixes, const char *prefix)
  * later free()ing) if the string passed in is a magic short-hand form
  * to name a branch.
  */
-static char *substitute_branch_name(const char **string, int *len)
+static char *substitute_branch_name(struct repository *r,
+                                   const char **string, int *len,
+                                   int nonfatal_dangling_mark)
 {
        struct strbuf buf = STRBUF_INIT;
-       int ret = interpret_branch_name(*string, *len, &buf, 0);
+       struct interpret_branch_name_options options = {
+               .nonfatal_dangling_mark = nonfatal_dangling_mark
+       };
+       int ret = repo_interpret_branch_name(r, *string, *len, &buf, &options);
 
        if (ret == *len) {
                size_t size;
@@ -545,15 +636,18 @@ static char *substitute_branch_name(const char **string, int *len)
        return NULL;
 }
 
-int dwim_ref(const char *str, int len, struct object_id *oid, char **ref)
+int repo_dwim_ref(struct repository *r, const char *str, int len,
+                 struct object_id *oid, char **ref, int nonfatal_dangling_mark)
 {
-       char *last_branch = substitute_branch_name(&str, &len);
-       int   refs_found  = expand_ref(str, len, oid, ref);
+       char *last_branch = substitute_branch_name(r, &str, &len,
+                                                  nonfatal_dangling_mark);
+       int   refs_found  = expand_ref(r, str, len, oid, ref);
        free(last_branch);
        return refs_found;
 }
 
-int expand_ref(const char *str, int len, struct object_id *oid, char **ref)
+int expand_ref(struct repository *repo, const char *str, int len,
+              struct object_id *oid, char **ref)
 {
        const char **p, *r;
        int refs_found = 0;
@@ -568,8 +662,9 @@ int expand_ref(const char *str, int len, struct object_id *oid, char **ref)
                this_result = refs_found ? &oid_from_ref : oid;
                strbuf_reset(&fullref);
                strbuf_addf(&fullref, *p, len, str);
-               r = resolve_ref_unsafe(fullref.buf, RESOLVE_REF_READING,
-                                      this_result, &flag);
+               r = refs_resolve_ref_unsafe(get_main_ref_store(repo),
+                                           fullref.buf, RESOLVE_REF_READING,
+                                           this_result, &flag);
                if (r) {
                        if (!refs_found++)
                                *ref = xstrdup(r);
@@ -585,9 +680,11 @@ int expand_ref(const char *str, int len, struct object_id *oid, char **ref)
        return refs_found;
 }
 
-int dwim_log(const char *str, int len, struct object_id *oid, char **log)
+int repo_dwim_log(struct repository *r, const char *str, int len,
+                 struct object_id *oid, char **log)
 {
-       char *last_branch = substitute_branch_name(&str, &len);
+       struct ref_store *refs = get_main_ref_store(r);
+       char *last_branch = substitute_branch_name(r, &str, &len, 0);
        const char **p;
        int logs_found = 0;
        struct strbuf path = STRBUF_INIT;
@@ -599,13 +696,15 @@ int dwim_log(const char *str, int len, struct object_id *oid, char **log)
 
                strbuf_reset(&path);
                strbuf_addf(&path, *p, len, str);
-               ref = resolve_ref_unsafe(path.buf, RESOLVE_REF_READING,
-                                        &hash, NULL);
+               ref = refs_resolve_ref_unsafe(refs, path.buf,
+                                             RESOLVE_REF_READING,
+                                             &hash, NULL);
                if (!ref)
                        continue;
-               if (reflog_exists(path.buf))
+               if (refs_reflog_exists(refs, path.buf))
                        it = path.buf;
-               else if (strcmp(ref, path.buf) && reflog_exists(ref))
+               else if (strcmp(ref, path.buf) &&
+                        refs_reflog_exists(refs, ref))
                        it = ref;
                else
                        continue;
@@ -621,11 +720,16 @@ int dwim_log(const char *str, int len, struct object_id *oid, char **log)
        return logs_found;
 }
 
+int dwim_log(const char *str, int len, struct object_id *oid, char **log)
+{
+       return repo_dwim_log(the_repository, str, len, oid, log);
+}
+
 static int is_per_worktree_ref(const char *refname)
 {
-       return !strcmp(refname, "HEAD") ||
-               starts_with(refname, "refs/bisect/") ||
-               starts_with(refname, "refs/rewritten/");
+       return starts_with(refname, "refs/worktree/") ||
+              starts_with(refname, "refs/bisect/") ||
+              starts_with(refname, "refs/rewritten/");
 }
 
 static int is_pseudoref_syntax(const char *refname)
@@ -640,13 +744,34 @@ static int is_pseudoref_syntax(const char *refname)
        return 1;
 }
 
+static int is_main_pseudoref_syntax(const char *refname)
+{
+       return skip_prefix(refname, "main-worktree/", &refname) &&
+               *refname &&
+               is_pseudoref_syntax(refname);
+}
+
+static int is_other_pseudoref_syntax(const char *refname)
+{
+       if (!skip_prefix(refname, "worktrees/", &refname))
+               return 0;
+       refname = strchr(refname, '/');
+       if (!refname || !refname[1])
+               return 0;
+       return is_pseudoref_syntax(refname + 1);
+}
+
 enum ref_type ref_type(const char *refname)
 {
        if (is_per_worktree_ref(refname))
                return REF_TYPE_PER_WORKTREE;
        if (is_pseudoref_syntax(refname))
                return REF_TYPE_PSEUDOREF;
-       return REF_TYPE_NORMAL;
+       if (is_main_pseudoref_syntax(refname))
+               return REF_TYPE_MAIN_PSEUDOREF;
+       if (is_other_pseudoref_syntax(refname))
+               return REF_TYPE_OTHER_PSEUDOREF;
+       return REF_TYPE_NORMAL;
 }
 
 long get_files_ref_lock_timeout_ms(void)
@@ -664,102 +789,6 @@ long get_files_ref_lock_timeout_ms(void)
        return timeout_ms;
 }
 
-static int write_pseudoref(const char *pseudoref, const struct object_id *oid,
-                          const struct object_id *old_oid, struct strbuf *err)
-{
-       const char *filename;
-       int fd;
-       struct lock_file lock = LOCK_INIT;
-       struct strbuf buf = STRBUF_INIT;
-       int ret = -1;
-
-       if (!oid)
-               return 0;
-
-       strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
-
-       filename = git_path("%s", pseudoref);
-       fd = hold_lock_file_for_update_timeout(&lock, filename, 0,
-                                              get_files_ref_lock_timeout_ms());
-       if (fd < 0) {
-               strbuf_addf(err, _("could not open '%s' for writing: %s"),
-                           filename, strerror(errno));
-               goto done;
-       }
-
-       if (old_oid) {
-               struct object_id actual_old_oid;
-
-               if (read_ref(pseudoref, &actual_old_oid)) {
-                       if (!is_null_oid(old_oid)) {
-                               strbuf_addf(err, _("could not read ref '%s'"),
-                                           pseudoref);
-                               rollback_lock_file(&lock);
-                               goto done;
-                       }
-               } else if (is_null_oid(old_oid)) {
-                       strbuf_addf(err, _("ref '%s' already exists"),
-                                   pseudoref);
-                       rollback_lock_file(&lock);
-                       goto done;
-               } else if (oidcmp(&actual_old_oid, old_oid)) {
-                       strbuf_addf(err, _("unexpected object ID when writing '%s'"),
-                                   pseudoref);
-                       rollback_lock_file(&lock);
-                       goto done;
-               }
-       }
-
-       if (write_in_full(fd, buf.buf, buf.len) < 0) {
-               strbuf_addf(err, _("could not write to '%s'"), filename);
-               rollback_lock_file(&lock);
-               goto done;
-       }
-
-       commit_lock_file(&lock);
-       ret = 0;
-done:
-       strbuf_release(&buf);
-       return ret;
-}
-
-static int delete_pseudoref(const char *pseudoref, const struct object_id *old_oid)
-{
-       const char *filename;
-
-       filename = git_path("%s", pseudoref);
-
-       if (old_oid && !is_null_oid(old_oid)) {
-               struct lock_file lock = LOCK_INIT;
-               int fd;
-               struct object_id actual_old_oid;
-
-               fd = hold_lock_file_for_update_timeout(
-                               &lock, filename, 0,
-                               get_files_ref_lock_timeout_ms());
-               if (fd < 0) {
-                       error_errno(_("could not open '%s' for writing"),
-                                   filename);
-                       return -1;
-               }
-               if (read_ref(pseudoref, &actual_old_oid))
-                       die(_("could not read ref '%s'"), pseudoref);
-               if (oidcmp(&actual_old_oid, old_oid)) {
-                       error(_("unexpected object ID when deleting '%s'"),
-                             pseudoref);
-                       rollback_lock_file(&lock);
-                       return -1;
-               }
-
-               unlink(filename);
-               rollback_lock_file(&lock);
-       } else {
-               unlink(filename);
-       }
-
-       return 0;
-}
-
 int refs_delete_ref(struct ref_store *refs, const char *msg,
                    const char *refname,
                    const struct object_id *old_oid,
@@ -768,11 +797,6 @@ int refs_delete_ref(struct ref_store *refs, const char *msg,
        struct ref_transaction *transaction;
        struct strbuf err = STRBUF_INIT;
 
-       if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
-               assert(refs == get_main_ref_store(the_repository));
-               return delete_pseudoref(refname, old_oid);
-       }
-
        transaction = ref_store_transaction_begin(refs, &err);
        if (!transaction ||
            ref_transaction_delete(transaction, refname, old_oid,
@@ -795,12 +819,11 @@ int delete_ref(const char *msg, const char *refname,
                               old_oid, flags);
 }
 
-void copy_reflog_msg(struct strbuf *sb, const char *msg)
+static void copy_reflog_msg(struct strbuf *sb, const char *msg)
 {
        char c;
        int wasspace = 1;
 
-       strbuf_addch(sb, '\t');
        while ((c = *msg++)) {
                if (wasspace && isspace(c))
                        continue;
@@ -812,6 +835,15 @@ void copy_reflog_msg(struct strbuf *sb, const char *msg)
        strbuf_rtrim(sb);
 }
 
+static char *normalize_reflog_message(const char *msg)
+{
+       struct strbuf sb = STRBUF_INIT;
+
+       if (msg && *msg)
+               copy_reflog_msg(&sb, msg);
+       return strbuf_detach(&sb, NULL);
+}
+
 int should_autocreate_reflog(const char *refname)
 {
        switch (log_all_ref_updates) {
@@ -875,13 +907,13 @@ static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
                 */
                if (!is_null_oid(&cb->ooid)) {
                        oidcpy(cb->oid, noid);
-                       if (oidcmp(&cb->ooid, noid))
+                       if (!oideq(&cb->ooid, noid))
                                warning(_("log for ref %s has gap after %s"),
                                        cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
                }
                else if (cb->date == cb->at_time)
                        oidcpy(cb->oid, noid);
-               else if (oidcmp(noid, cb->oid))
+               else if (!oideq(noid, cb->oid))
                        warning(_("log for ref %s unexpectedly ended on %s"),
                                cb->refname, show_date(cb->date, cb->tz,
                                                       DATE_MODE(RFC2822)));
@@ -918,7 +950,8 @@ static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid
        return 1;
 }
 
-int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, int cnt,
+int read_ref_at(struct ref_store *refs, const char *refname,
+               unsigned int flags, timestamp_t at_time, int cnt,
                struct object_id *oid, char **msg,
                timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 {
@@ -934,7 +967,7 @@ int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, in
        cb.cutoff_cnt = cutoff_cnt;
        cb.oid = oid;
 
-       for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
+       refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent, &cb);
 
        if (!cb.reccnt) {
                if (flags & GET_OID_QUIETLY)
@@ -945,7 +978,7 @@ int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, in
        if (cb.found_it)
                return 0;
 
-       for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
+       refs_for_each_reflog_ent(refs, refname, read_ref_at_ent_oldest, &cb);
 
        return 1;
 }
@@ -1016,7 +1049,7 @@ struct ref_update *ref_transaction_add_update(
                oidcpy(&update->new_oid, new_oid);
        if (flags & REF_HAVE_OLD)
                oidcpy(&update->old_oid, old_oid);
-       update->msg = xstrdup_or_null(msg);
+       update->msg = normalize_reflog_message(msg);
        return update;
 }
 
@@ -1094,18 +1127,13 @@ int refs_update_ref(struct ref_store *refs, const char *msg,
        struct strbuf err = STRBUF_INIT;
        int ret = 0;
 
-       if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
-               assert(refs == get_main_ref_store(the_repository));
-               ret = write_pseudoref(refname, new_oid, old_oid, &err);
-       } else {
-               t = ref_store_transaction_begin(refs, &err);
-               if (!t ||
-                   ref_transaction_update(t, refname, new_oid, old_oid,
-                                          flags, msg, &err) ||
-                   ref_transaction_commit(t, &err)) {
-                       ret = 1;
-                       ref_transaction_free(t);
-               }
+       t = ref_store_transaction_begin(refs, &err);
+       if (!t ||
+           ref_transaction_update(t, refname, new_oid, old_oid, flags, msg,
+                                  &err) ||
+           ref_transaction_commit(t, &err)) {
+               ret = 1;
+               ref_transaction_free(t);
        }
        if (ret) {
                const char *str = _("update_ref failed for ref '%s': %s");
@@ -1138,7 +1166,8 @@ int update_ref(const char *msg, const char *refname,
                               old_oid, flags, onerr);
 }
 
-char *shorten_unambiguous_ref(const char *refname, int strict)
+char *refs_shorten_unambiguous_ref(struct ref_store *refs,
+                                  const char *refname, int strict)
 {
        int i;
        static char **scanf_fmts;
@@ -1216,7 +1245,7 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
                        strbuf_reset(&resolved_buf);
                        strbuf_addf(&resolved_buf, rule,
                                    short_name_len, short_name);
-                       if (ref_exists(resolved_buf.buf))
+                       if (refs_ref_exists(refs, resolved_buf.buf))
                                break;
                }
 
@@ -1235,6 +1264,12 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
        return xstrdup(refname);
 }
 
+char *shorten_unambiguous_ref(const char *refname, int strict)
+{
+       return refs_shorten_unambiguous_ref(get_main_ref_store(the_repository),
+                                           refname, strict);
+}
+
 static struct string_list *hide_refs;
 
 int parse_hide_refs_config(const char *var, const char *value, const char *section)
@@ -1511,11 +1546,37 @@ int for_each_rawref(each_ref_fn fn, void *cb_data)
        return refs_for_each_rawref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
+static int refs_read_special_head(struct ref_store *ref_store,
+                                 const char *refname, struct object_id *oid,
+                                 struct strbuf *referent, unsigned int *type)
+{
+       struct strbuf full_path = STRBUF_INIT;
+       struct strbuf content = STRBUF_INIT;
+       int result = -1;
+       strbuf_addf(&full_path, "%s/%s", ref_store->gitdir, refname);
+
+       if (strbuf_read_file(&content, full_path.buf, 0) < 0)
+               goto done;
+
+       result = parse_loose_ref_contents(content.buf, oid, referent, type);
+
+done:
+       strbuf_release(&full_path);
+       strbuf_release(&content);
+       return result;
+}
+
 int refs_read_raw_ref(struct ref_store *ref_store,
                      const char *refname, struct object_id *oid,
                      struct strbuf *referent, unsigned int *type)
 {
-       return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, type);
+       if (!strcmp(refname, "FETCH_HEAD") || !strcmp(refname, "MERGE_HEAD")) {
+               return refs_read_special_head(ref_store, refname, oid, referent,
+                                             type);
+       }
+
+       return ref_store->be->read_raw_ref(ref_store, refname, oid, referent,
+                                          type);
 }
 
 /* This function needs to return a meaningful errno on failure */
@@ -1645,7 +1706,7 @@ int resolve_gitlink_ref(const char *submodule, const char *refname,
 
 struct ref_store_hash_entry
 {
-       struct hashmap_entry ent; /* must be the first member! */
+       struct hashmap_entry ent;
 
        struct ref_store *refs;
 
@@ -1654,11 +1715,16 @@ struct ref_store_hash_entry
 };
 
 static int ref_store_hash_cmp(const void *unused_cmp_data,
-                             const void *entry, const void *entry_or_key,
+                             const struct hashmap_entry *eptr,
+                             const struct hashmap_entry *entry_or_key,
                              const void *keydata)
 {
-       const struct ref_store_hash_entry *e1 = entry, *e2 = entry_or_key;
-       const char *name = keydata ? keydata : e2->name;
+       const struct ref_store_hash_entry *e1, *e2;
+       const char *name;
+
+       e1 = container_of(eptr, const struct ref_store_hash_entry, ent);
+       e2 = container_of(entry_or_key, const struct ref_store_hash_entry, ent);
+       name = keydata ? keydata : e2->name;
 
        return strcmp(e1->name, name);
 }
@@ -1669,7 +1735,7 @@ static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
        struct ref_store_hash_entry *entry;
 
        FLEX_ALLOC_STR(entry, name, name);
-       hashmap_entry_init(entry, strhash(name));
+       hashmap_entry_init(&entry->ent, strhash(name));
        entry->refs = refs;
        return entry;
 }
@@ -1688,12 +1754,15 @@ static struct ref_store *lookup_ref_store_map(struct hashmap *map,
                                              const char *name)
 {
        struct ref_store_hash_entry *entry;
+       unsigned int hash;
 
        if (!map->tablesize)
                /* It's initialized on demand in register_ref_store(). */
                return NULL;
 
-       entry = hashmap_get_from_hash(map, strhash(name), name);
+       hash = strhash(name);
+       entry = hashmap_get_entry_from_hash(map, hash, name,
+                                       struct ref_store_hash_entry, ent);
        return entry ? entry->refs : NULL;
 }
 
@@ -1717,14 +1786,15 @@ static struct ref_store *ref_store_init(const char *gitdir,
 
 struct ref_store *get_main_ref_store(struct repository *r)
 {
-       if (r->refs)
-               return r->refs;
+       if (r->refs_private)
+               return r->refs_private;
 
        if (!r->gitdir)
                BUG("attempting to get main_ref_store outside of repository");
 
-       r->refs = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
-       return r->refs;
+       r->refs_private = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
+       r->refs_private = maybe_debug_wrap_ref_store(r->gitdir, r->refs_private);
+       return r->refs_private;
 }
 
 /*
@@ -1736,10 +1806,13 @@ static void register_ref_store_map(struct hashmap *map,
                                   struct ref_store *refs,
                                   const char *name)
 {
+       struct ref_store_hash_entry *entry;
+
        if (!map->tablesize)
                hashmap_init(map, ref_store_hash_cmp, NULL, 0);
 
-       if (hashmap_put(map, alloc_ref_store_hash_entry(name, refs)))
+       entry = alloc_ref_store_hash_entry(name, refs);
+       if (hashmap_put(map, &entry->ent))
                BUG("%s ref_store '%s' initialized twice", type, name);
 }
 
@@ -1857,9 +1930,14 @@ int refs_create_symref(struct ref_store *refs,
                       const char *refs_heads_master,
                       const char *logmsg)
 {
-       return refs->be->create_symref(refs, ref_target,
-                                      refs_heads_master,
-                                      logmsg);
+       char *msg;
+       int retval;
+
+       msg = normalize_reflog_message(logmsg);
+       retval = refs->be->create_symref(refs, ref_target, refs_heads_master,
+                                        msg);
+       free(msg);
+       return retval;
 }
 
 int create_symref(const char *ref_target, const char *refs_heads_master,
@@ -1892,10 +1970,58 @@ int ref_update_reject_duplicates(struct string_list *refnames,
        return 0;
 }
 
+static int run_transaction_hook(struct ref_transaction *transaction,
+                               const char *state)
+{
+       struct child_process proc = CHILD_PROCESS_INIT;
+       struct strbuf buf = STRBUF_INIT;
+       const char *hook;
+       int ret = 0, i;
+
+       hook = find_hook("reference-transaction");
+       if (!hook)
+               return ret;
+
+       strvec_pushl(&proc.args, hook, state, NULL);
+       proc.in = -1;
+       proc.stdout_to_stderr = 1;
+       proc.trace2_hook_name = "reference-transaction";
+
+       ret = start_command(&proc);
+       if (ret)
+               return ret;
+
+       sigchain_push(SIGPIPE, SIG_IGN);
+
+       for (i = 0; i < transaction->nr; i++) {
+               struct ref_update *update = transaction->updates[i];
+
+               strbuf_reset(&buf);
+               strbuf_addf(&buf, "%s %s %s\n",
+                           oid_to_hex(&update->old_oid),
+                           oid_to_hex(&update->new_oid),
+                           update->refname);
+
+               if (write_in_full(proc.in, buf.buf, buf.len) < 0) {
+                       if (errno != EPIPE)
+                               ret = -1;
+                       break;
+               }
+       }
+
+       close(proc.in);
+       sigchain_pop(SIGPIPE);
+       strbuf_release(&buf);
+
+       ret |= finish_command(&proc);
+       return ret;
+}
+
 int ref_transaction_prepare(struct ref_transaction *transaction,
                            struct strbuf *err)
 {
        struct ref_store *refs = transaction->ref_store;
+       int ret;
 
        switch (transaction->state) {
        case REF_TRANSACTION_OPEN:
@@ -1918,7 +2044,17 @@ int ref_transaction_prepare(struct ref_transaction *transaction,
                return -1;
        }
 
-       return refs->be->transaction_prepare(refs, transaction, err);
+       ret = refs->be->transaction_prepare(refs, transaction, err);
+       if (ret)
+               return ret;
+
+       ret = run_transaction_hook(transaction, "prepared");
+       if (ret) {
+               ref_transaction_abort(transaction, err);
+               die(_("ref updates aborted by hook"));
+       }
+
+       return 0;
 }
 
 int ref_transaction_abort(struct ref_transaction *transaction,
@@ -1942,6 +2078,8 @@ int ref_transaction_abort(struct ref_transaction *transaction,
                break;
        }
 
+       run_transaction_hook(transaction, "aborted");
+
        ref_transaction_free(transaction);
        return ret;
 }
@@ -1970,7 +2108,10 @@ int ref_transaction_commit(struct ref_transaction *transaction,
                break;
        }
 
-       return refs->be->transaction_finish(refs, transaction, err);
+       ret = refs->be->transaction_finish(refs, transaction, err);
+       if (!ret)
+               run_transaction_hook(transaction, "committed");
+       return ret;
 }
 
 int refs_verify_refname_available(struct ref_store *refs,
@@ -2174,10 +2315,16 @@ int initial_ref_transaction_commit(struct ref_transaction *transaction,
        return refs->be->initial_transaction_commit(refs, transaction, err);
 }
 
-int refs_delete_refs(struct ref_store *refs, const char *msg,
+int refs_delete_refs(struct ref_store *refs, const char *logmsg,
                     struct string_list *refnames, unsigned int flags)
 {
-       return refs->be->delete_refs(refs, msg, refnames, flags);
+       char *msg;
+       int retval;
+
+       msg = normalize_reflog_message(logmsg);
+       retval = refs->be->delete_refs(refs, msg, refnames, flags);
+       free(msg);
+       return retval;
 }
 
 int delete_refs(const char *msg, struct string_list *refnames,
@@ -2189,7 +2336,13 @@ int delete_refs(const char *msg, struct string_list *refnames,
 int refs_rename_ref(struct ref_store *refs, const char *oldref,
                    const char *newref, const char *logmsg)
 {
-       return refs->be->rename_ref(refs, oldref, newref, logmsg);
+       char *msg;
+       int retval;
+
+       msg = normalize_reflog_message(logmsg);
+       retval = refs->be->rename_ref(refs, oldref, newref, msg);
+       free(msg);
+       return retval;
 }
 
 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
@@ -2200,7 +2353,13 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
                    const char *newref, const char *logmsg)
 {
-       return refs->be->copy_ref(refs, oldref, newref, logmsg);
+       char *msg;
+       int retval;
+
+       msg = normalize_reflog_message(logmsg);
+       retval = refs->be->copy_ref(refs, oldref, newref, msg);
+       free(msg);
+       return retval;
 }
 
 int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)