builtin/checkout.c

   1 #include "builtin.h"
   2 #include "lockfile.h"
   3 #include "parse-options.h"
   4 #include "refs.h"
   5 #include "commit.h"
   6 #include "tree.h"
   7 #include "tree-walk.h"
   8 #include "cache-tree.h"
   9 #include "unpack-trees.h"
  10 #include "dir.h"
  11 #include "run-command.h"
  12 #include "merge-recursive.h"
  13 #include "branch.h"
  14 #include "diff.h"
  15 #include "revision.h"
  16 #include "remote.h"
  17 #include "blob.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "resolve-undo.h"
  21 #include "submodule.h"
  22 #include "argv-array.h"
  23
  24 static const char * const checkout_usage[] = {
  25         N_("git checkout [options] <branch>"),
  26         N_("git checkout [options] [<branch>] -- <file>..."),
  27         NULL,
  28 };
  29
  30 struct checkout_opts {
  31         int patch_mode;
  32         int quiet;
  33         int merge;
  34         int force;
  35         int force_detach;
  36         int writeout_stage;
  37         int overwrite_ignore;
  38         int ignore_skipworktree;
  39
  40         const char *new_branch;
  41         const char *new_branch_force;
  42         const char *new_orphan_branch;
  43         int new_branch_log;
  44         enum branch_track track;
  45         struct diff_options diff_options;
  46
  47         int branch_exists;
  48         const char *prefix;
  49         struct pathspec pathspec;
  50         struct tree *source_tree;
  51 };
  52
  53 static int post_checkout_hook(struct commit *old, struct commit *new,
  54                               int changed)
  55 {
  56         return run_hook_le(NULL, "post-checkout",
  57                            sha1_to_hex(old ? old->object.sha1 : null_sha1),
  58                            sha1_to_hex(new ? new->object.sha1 : null_sha1),
  59                            changed ? "1" : "0", NULL);
  60         /* "new" can be NULL when checking out from the index before
  61            a commit exists. */
  62
  63 }
  64
  65 static int update_some(const unsigned char *sha1, const char *base, int baselen,
  66                 const char *pathname, unsigned mode, int stage, void *context)
  67 {
  68         int len;
  69         struct cache_entry *ce;
  70
  71         if (S_ISDIR(mode))
  72                 return READ_TREE_RECURSIVE;
  73
  74         len = baselen + strlen(pathname);
  75         ce = xcalloc(1, cache_entry_size(len));
  76         hashcpy(ce->sha1, sha1);
  77         memcpy(ce->name, base, baselen);
  78         memcpy(ce->name + baselen, pathname, len - baselen);
  79         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  80         ce->ce_namelen = len;
  81         ce->ce_mode = create_ce_mode(mode);
  82         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
  83         return 0;
  84 }
  85
  86 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
  87 {
  88         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
  89
  90         /* update the index with the given tree's info
  91          * for all args, expanding wildcards, and exit
  92          * with any non-zero return code.
  93          */
  94         return 0;
  95 }
  96
  97 static int skip_same_name(const struct cache_entry *ce, int pos)
  98 {
  99         while (++pos < active_nr &&
 100                !strcmp(active_cache[pos]->name, ce->name))
 101                 ; /* skip */
 102         return pos;
 103 }
 104
 105 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 106 {
 107         while (pos < active_nr &&
 108                !strcmp(active_cache[pos]->name, ce->name)) {
 109                 if (ce_stage(active_cache[pos]) == stage)
 110                         return 0;
 111                 pos++;
 112         }
 113         if (stage == 2)
 114                 return error(_("path '%s' does not have our version"), ce->name);
 115         else
 116                 return error(_("path '%s' does not have their version"), ce->name);
 117 }
 118
 119 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 120 {
 121         unsigned seen = 0;
 122         const char *name = ce->name;
 123
 124         while (pos < active_nr) {
 125                 ce = active_cache[pos];
 126                 if (strcmp(name, ce->name))
 127                         break;
 128                 seen |= (1 << ce_stage(ce));
 129                 pos++;
 130         }
 131         if ((stages & seen) != stages)
 132                 return error(_("path '%s' does not have all necessary versions"),
 133                              name);
 134         return 0;
 135 }
 136
 137 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 138                           struct checkout *state)
 139 {
 140         while (pos < active_nr &&
 141                !strcmp(active_cache[pos]->name, ce->name)) {
 142                 if (ce_stage(active_cache[pos]) == stage)
 143                         return checkout_entry(active_cache[pos], state, NULL);
 144                 pos++;
 145         }
 146         if (stage == 2)
 147                 return error(_("path '%s' does not have our version"), ce->name);
 148         else
 149                 return error(_("path '%s' does not have their version"), ce->name);
 150 }
 151
 152 static int checkout_merged(int pos, struct checkout *state)
 153 {
 154         struct cache_entry *ce = active_cache[pos];
 155         const char *path = ce->name;
 156         mmfile_t ancestor, ours, theirs;
 157         int status;
 158         unsigned char sha1[20];
 159         mmbuffer_t result_buf;
 160         unsigned char threeway[3][20];
 161         unsigned mode = 0;
 162
 163         memset(threeway, 0, sizeof(threeway));
 164         while (pos < active_nr) {
 165                 int stage;
 166                 stage = ce_stage(ce);
 167                 if (!stage || strcmp(path, ce->name))
 168                         break;
 169                 hashcpy(threeway[stage - 1], ce->sha1);
 170                 if (stage == 2)
 171                         mode = create_ce_mode(ce->ce_mode);
 172                 pos++;
 173                 ce = active_cache[pos];
 174         }
 175         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
 176                 return error(_("path '%s' does not have necessary versions"), path);
 177
 178         read_mmblob(&ancestor, threeway[0]);
 179         read_mmblob(&ours, threeway[1]);
 180         read_mmblob(&theirs, threeway[2]);
 181
 182         /*
 183          * NEEDSWORK: re-create conflicts from merges with
 184          * merge.renormalize set, too
 185          */
 186         status = ll_merge(&result_buf, path, &ancestor, "base",
 187                           &ours, "ours", &theirs, "theirs", NULL);
 188         free(ancestor.ptr);
 189         free(ours.ptr);
 190         free(theirs.ptr);
 191         if (status < 0 || !result_buf.ptr) {
 192                 free(result_buf.ptr);
 193                 return error(_("path '%s': cannot merge"), path);
 194         }
 195
 196         /*
 197          * NEEDSWORK:
 198          * There is absolutely no reason to write this as a blob object
 199          * and create a phony cache entry just to leak.  This hack is
 200          * primarily to get to the write_entry() machinery that massages
 201          * the contents to work-tree format and writes out which only
 202          * allows it for a cache entry.  The code in write_entry() needs
 203          * to be refactored to allow us to feed a <buffer, size, mode>
 204          * instead of a cache entry.  Such a refactoring would help
 205          * merge_recursive as well (it also writes the merge result to the
 206          * object database even when it may contain conflicts).
 207          */
 208         if (write_sha1_file(result_buf.ptr, result_buf.size,
 209                             blob_type, sha1))
 210                 die(_("Unable to add merge result for '%s'"), path);
 211         ce = make_cache_entry(mode, sha1, path, 2, 0);
 212         if (!ce)
 213                 die(_("make_cache_entry failed for path '%s'"), path);
 214         status = checkout_entry(ce, state, NULL);
 215         return status;
 216 }
 217
 218 static int checkout_paths(const struct checkout_opts *opts,
 219                           const char *revision)
 220 {
 221         int pos;
 222         struct checkout state;
 223         static char *ps_matched;
 224         unsigned char rev[20];
 225         int flag;
 226         struct commit *head;
 227         int errs = 0;
 228         struct lock_file *lock_file;
 229
 230         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 231                 die(_("'%s' cannot be used with updating paths"), "--track");
 232
 233         if (opts->new_branch_log)
 234                 die(_("'%s' cannot be used with updating paths"), "-l");
 235
 236         if (opts->force && opts->patch_mode)
 237                 die(_("'%s' cannot be used with updating paths"), "-f");
 238
 239         if (opts->force_detach)
 240                 die(_("'%s' cannot be used with updating paths"), "--detach");
 241
 242         if (opts->merge && opts->patch_mode)
 243                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 244
 245         if (opts->force && opts->merge)
 246                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 247
 248         if (opts->new_branch)
 249                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 250                     opts->new_branch);
 251
 252         if (opts->patch_mode)
 253                 return run_add_interactive(revision, "--patch=checkout",
 254                                            &opts->pathspec);
 255
 256         lock_file = xcalloc(1, sizeof(struct lock_file));
 257
 258         hold_locked_index(lock_file, 1);
 259         if (read_cache_preload(&opts->pathspec) < 0)
 260                 return error(_("corrupt index file"));
 261
 262         if (opts->source_tree)
 263                 read_tree_some(opts->source_tree, &opts->pathspec);
 264
 265         ps_matched = xcalloc(1, opts->pathspec.nr);
 266
 267         /*
 268          * Make sure all pathspecs participated in locating the paths
 269          * to be checked out.
 270          */
 271         for (pos = 0; pos < active_nr; pos++) {
 272                 struct cache_entry *ce = active_cache[pos];
 273                 ce->ce_flags &= ~CE_MATCHED;
 274                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 275                         continue;
 276                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 277                         /*
 278                          * "git checkout tree-ish -- path", but this entry
 279                          * is in the original index; it will not be checked
 280                          * out to the working tree and it does not matter
 281                          * if pathspec matched this entry.  We will not do
 282                          * anything to this entry at all.
 283                          */
 284                         continue;
 285                 /*
 286                  * Either this entry came from the tree-ish we are
 287                  * checking the paths out of, or we are checking out
 288                  * of the index.
 289                  *
 290                  * If it comes from the tree-ish, we already know it
 291                  * matches the pathspec and could just stamp
 292                  * CE_MATCHED to it from update_some(). But we still
 293                  * need ps_matched and read_tree_recursive (and
 294                  * eventually tree_entry_interesting) cannot fill
 295                  * ps_matched yet. Once it can, we can avoid calling
 296                  * match_pathspec() for _all_ entries when
 297                  * opts->source_tree != NULL.
 298                  */
 299                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
 300                         ce->ce_flags |= CE_MATCHED;
 301         }
 302
 303         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 304                 free(ps_matched);
 305                 return 1;
 306         }
 307         free(ps_matched);
 308
 309         /* "checkout -m path" to recreate conflicted state */
 310         if (opts->merge)
 311                 unmerge_marked_index(&the_index);
 312
 313         /* Any unmerged paths? */
 314         for (pos = 0; pos < active_nr; pos++) {
 315                 const struct cache_entry *ce = active_cache[pos];
 316                 if (ce->ce_flags & CE_MATCHED) {
 317                         if (!ce_stage(ce))
 318                                 continue;
 319                         if (opts->force) {
 320                                 warning(_("path '%s' is unmerged"), ce->name);
 321                         } else if (opts->writeout_stage) {
 322                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 323                         } else if (opts->merge) {
 324                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 325                         } else {
 326                                 errs = 1;
 327                                 error(_("path '%s' is unmerged"), ce->name);
 328                         }
 329                         pos = skip_same_name(ce, pos) - 1;
 330                 }
 331         }
 332         if (errs)
 333                 return 1;
 334
 335         /* Now we are committed to check them out */
 336         memset(&state, 0, sizeof(state));
 337         state.force = 1;
 338         state.refresh_cache = 1;
 339         state.istate = &the_index;
 340         for (pos = 0; pos < active_nr; pos++) {
 341                 struct cache_entry *ce = active_cache[pos];
 342                 if (ce->ce_flags & CE_MATCHED) {
 343                         if (!ce_stage(ce)) {
 344                                 errs |= checkout_entry(ce, &state, NULL);
 345                                 continue;
 346                         }
 347                         if (opts->writeout_stage)
 348                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 349                         else if (opts->merge)
 350                                 errs |= checkout_merged(pos, &state);
 351                         pos = skip_same_name(ce, pos) - 1;
 352                 }
 353         }
 354
 355         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 356                 die(_("unable to write new index file"));
 357
 358         read_ref_full("HEAD", 0, rev, &flag);
 359         head = lookup_commit_reference_gently(rev, 1);
 360
 361         errs |= post_checkout_hook(head, head, 0);
 362         return errs;
 363 }
 364
 365 static void show_local_changes(struct object *head,
 366                                const struct diff_options *opts)
 367 {
 368         struct rev_info rev;
 369         /* I think we want full paths, even if we're in a subdirectory. */
 370         init_revisions(&rev, NULL);
 371         rev.diffopt.flags = opts->flags;
 372         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 373         diff_setup_done(&rev.diffopt);
 374         add_pending_object(&rev, head, NULL);
 375         run_diff_index(&rev, 0);
 376 }
 377
 378 static void describe_detached_head(const char *msg, struct commit *commit)
 379 {
 380         struct strbuf sb = STRBUF_INIT;
 381         if (!parse_commit(commit))
 382                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 383         fprintf(stderr, "%s %s... %s\n", msg,
 384                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 385         strbuf_release(&sb);
 386 }
 387
 388 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 389                       int worktree, int *writeout_error)
 390 {
 391         struct unpack_trees_options opts;
 392         struct tree_desc tree_desc;
 393
 394         memset(&opts, 0, sizeof(opts));
 395         opts.head_idx = -1;
 396         opts.update = worktree;
 397         opts.skip_unmerged = !worktree;
 398         opts.reset = 1;
 399         opts.merge = 1;
 400         opts.fn = oneway_merge;
 401         opts.verbose_update = !o->quiet && isatty(2);
 402         opts.src_index = &the_index;
 403         opts.dst_index = &the_index;
 404         parse_tree(tree);
 405         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 406         switch (unpack_trees(1, &tree_desc, &opts)) {
 407         case -2:
 408                 *writeout_error = 1;
 409                 /*
 410                  * We return 0 nevertheless, as the index is all right
 411                  * and more importantly we have made best efforts to
 412                  * update paths in the work tree, and we cannot revert
 413                  * them.
 414                  */
 415         case 0:
 416                 return 0;
 417         default:
 418                 return 128;
 419         }
 420 }
 421
 422 struct branch_info {
 423         const char *name; /* The short name used */
 424         const char *path; /* The full name of a real branch */
 425         struct commit *commit; /* The named commit */
 426 };
 427
 428 static void setup_branch_path(struct branch_info *branch)
 429 {
 430         struct strbuf buf = STRBUF_INIT;
 431
 432         strbuf_branchname(&buf, branch->name);
 433         if (strcmp(buf.buf, branch->name))
 434                 branch->name = xstrdup(buf.buf);
 435         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 436         branch->path = strbuf_detach(&buf, NULL);
 437 }
 438
 439 static int merge_working_tree(const struct checkout_opts *opts,
 440                               struct branch_info *old,
 441                               struct branch_info *new,
 442                               int *writeout_error)
 443 {
 444         int ret;
 445         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 446
 447         hold_locked_index(lock_file, 1);
 448         if (read_cache_preload(NULL) < 0)
 449                 return error(_("corrupt index file"));
 450
 451         resolve_undo_clear();
 452         if (opts->force) {
 453                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 454                 if (ret)
 455                         return ret;
 456         } else {
 457                 struct tree_desc trees[2];
 458                 struct tree *tree;
 459                 struct unpack_trees_options topts;
 460
 461                 memset(&topts, 0, sizeof(topts));
 462                 topts.head_idx = -1;
 463                 topts.src_index = &the_index;
 464                 topts.dst_index = &the_index;
 465
 466                 setup_unpack_trees_porcelain(&topts, "checkout");
 467
 468                 refresh_cache(REFRESH_QUIET);
 469
 470                 if (unmerged_cache()) {
 471                         error(_("you need to resolve your current index first"));
 472                         return 1;
 473                 }
 474
 475                 /* 2-way merge to the new branch */
 476                 topts.initial_checkout = is_cache_unborn();
 477                 topts.update = 1;
 478                 topts.merge = 1;
 479                 topts.gently = opts->merge && old->commit;
 480                 topts.verbose_update = !opts->quiet && isatty(2);
 481                 topts.fn = twoway_merge;
 482                 if (opts->overwrite_ignore) {
 483                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 484                         topts.dir->flags |= DIR_SHOW_IGNORED;
 485                         setup_standard_excludes(topts.dir);
 486                 }
 487                 tree = parse_tree_indirect(old->commit ?
 488                                            old->commit->object.sha1 :
 489                                            EMPTY_TREE_SHA1_BIN);
 490                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 491                 tree = parse_tree_indirect(new->commit->object.sha1);
 492                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 493
 494                 ret = unpack_trees(2, trees, &topts);
 495                 if (ret == -1) {
 496                         /*
 497                          * Unpack couldn't do a trivial merge; either
 498                          * give up or do a real merge, depending on
 499                          * whether the merge flag was used.
 500                          */
 501                         struct tree *result;
 502                         struct tree *work;
 503                         struct merge_options o;
 504                         if (!opts->merge)
 505                                 return 1;
 506
 507                         /*
 508                          * Without old->commit, the below is the same as
 509                          * the two-tree unpack we already tried and failed.
 510                          */
 511                         if (!old->commit)
 512                                 return 1;
 513
 514                         /* Do more real merge */
 515
 516                         /*
 517                          * We update the index fully, then write the
 518                          * tree from the index, then merge the new
 519                          * branch with the current tree, with the old
 520                          * branch as the base. Then we reset the index
 521                          * (but not the working tree) to the new
 522                          * branch, leaving the working tree as the
 523                          * merged version, but skipping unmerged
 524                          * entries in the index.
 525                          */
 526
 527                         add_files_to_cache(NULL, NULL, 0);
 528                         /*
 529                          * NEEDSWORK: carrying over local changes
 530                          * when branches have different end-of-line
 531                          * normalization (or clean+smudge rules) is
 532                          * a pain; plumb in an option to set
 533                          * o.renormalize?
 534                          */
 535                         init_merge_options(&o);
 536                         o.verbosity = 0;
 537                         work = write_tree_from_memory(&o);
 538
 539                         ret = reset_tree(new->commit->tree, opts, 1,
 540                                          writeout_error);
 541                         if (ret)
 542                                 return ret;
 543                         o.ancestor = old->name;
 544                         o.branch1 = new->name;
 545                         o.branch2 = "local";
 546                         merge_trees(&o, new->commit->tree, work,
 547                                 old->commit->tree, &result);
 548                         ret = reset_tree(new->commit->tree, opts, 0,
 549                                          writeout_error);
 550                         if (ret)
 551                                 return ret;
 552                 }
 553         }
 554
 555         if (!active_cache_tree)
 556                 active_cache_tree = cache_tree();
 557
 558         if (!cache_tree_fully_valid(active_cache_tree))
 559                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 560
 561         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 562                 die(_("unable to write new index file"));
 563
 564         if (!opts->force && !opts->quiet)
 565                 show_local_changes(&new->commit->object, &opts->diff_options);
 566
 567         return 0;
 568 }
 569
 570 static void report_tracking(struct branch_info *new)
 571 {
 572         struct strbuf sb = STRBUF_INIT;
 573         struct branch *branch = branch_get(new->name);
 574
 575         if (!format_tracking_info(branch, &sb))
 576                 return;
 577         fputs(sb.buf, stdout);
 578         strbuf_release(&sb);
 579 }
 580
 581 static void update_refs_for_switch(const struct checkout_opts *opts,
 582                                    struct branch_info *old,
 583                                    struct branch_info *new)
 584 {
 585         struct strbuf msg = STRBUF_INIT;
 586         const char *old_desc, *reflog_msg;
 587         if (opts->new_branch) {
 588                 if (opts->new_orphan_branch) {
 589                         if (opts->new_branch_log && !log_all_ref_updates) {
 590                                 int temp;
 591                                 char log_file[PATH_MAX];
 592                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 593
 594                                 temp = log_all_ref_updates;
 595                                 log_all_ref_updates = 1;
 596                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 597                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 598                                             opts->new_orphan_branch);
 599                                         log_all_ref_updates = temp;
 600                                         return;
 601                                 }
 602                                 log_all_ref_updates = temp;
 603                         }
 604                 }
 605                 else
 606                         create_branch(old->name, opts->new_branch, new->name,
 607                                       opts->new_branch_force ? 1 : 0,
 608                                       opts->new_branch_log,
 609                                       opts->new_branch_force ? 1 : 0,
 610                                       opts->quiet,
 611                                       opts->track);
 612                 new->name = opts->new_branch;
 613                 setup_branch_path(new);
 614         }
 615
 616         old_desc = old->name;
 617         if (!old_desc && old->commit)
 618                 old_desc = sha1_to_hex(old->commit->object.sha1);
 619
 620         reflog_msg = getenv("GIT_REFLOG_ACTION");
 621         if (!reflog_msg)
 622                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 623                         old_desc ? old_desc : "(invalid)", new->name);
 624         else
 625                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 626
 627         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 628                 /* Nothing to do. */
 629         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 630                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 631                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 632                 if (!opts->quiet) {
 633                         if (old->path && advice_detached_head)
 634                                 detach_advice(new->name);
 635                         describe_detached_head(_("HEAD is now at"), new->commit);
 636                 }
 637         } else if (new->path) { /* Switch branches. */
 638                 create_symref("HEAD", new->path, msg.buf);
 639                 if (!opts->quiet) {
 640                         if (old->path && !strcmp(new->path, old->path)) {
 641                                 if (opts->new_branch_force)
 642                                         fprintf(stderr, _("Reset branch '%s'\n"),
 643                                                 new->name);
 644                                 else
 645                                         fprintf(stderr, _("Already on '%s'\n"),
 646                                                 new->name);
 647                         } else if (opts->new_branch) {
 648                                 if (opts->branch_exists)
 649                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 650                                 else
 651                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 652                         } else {
 653                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 654                                         new->name);
 655                         }
 656                 }
 657                 if (old->path && old->name) {
 658                         if (!ref_exists(old->path) && reflog_exists(old->path))
 659                                 delete_reflog(old->path);
 660                 }
 661         }
 662         remove_branch_state();
 663         strbuf_release(&msg);
 664         if (!opts->quiet &&
 665             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 666                 report_tracking(new);
 667 }
 668
 669 static int add_pending_uninteresting_ref(const char *refname,
 670                                          const unsigned char *sha1,
 671                                          int flags, void *cb_data)
 672 {
 673         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 674         return 0;
 675 }
 676
 677 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 678 {
 679         strbuf_addstr(sb, "  ");
 680         strbuf_addstr(sb,
 681                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 682         strbuf_addch(sb, ' ');
 683         if (!parse_commit(commit))
 684                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 685         strbuf_addch(sb, '\n');
 686 }
 687
 688 #define ORPHAN_CUTOFF 4
 689 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 690 {
 691         struct commit *c, *last = NULL;
 692         struct strbuf sb = STRBUF_INIT;
 693         int lost = 0;
 694         while ((c = get_revision(revs)) != NULL) {
 695                 if (lost < ORPHAN_CUTOFF)
 696                         describe_one_orphan(&sb, c);
 697                 last = c;
 698                 lost++;
 699         }
 700         if (ORPHAN_CUTOFF < lost) {
 701                 int more = lost - ORPHAN_CUTOFF;
 702                 if (more == 1)
 703                         describe_one_orphan(&sb, last);
 704                 else
 705                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 706         }
 707
 708         fprintf(stderr,
 709                 Q_(
 710                 /* The singular version */
 711                 "Warning: you are leaving %d commit behind, "
 712                 "not connected to\n"
 713                 "any of your branches:\n\n"
 714                 "%s\n",
 715                 /* The plural version */
 716                 "Warning: you are leaving %d commits behind, "
 717                 "not connected to\n"
 718                 "any of your branches:\n\n"
 719                 "%s\n",
 720                 /* Give ngettext() the count */
 721                 lost),
 722                 lost,
 723                 sb.buf);
 724         strbuf_release(&sb);
 725
 726         if (advice_detached_head)
 727                 fprintf(stderr,
 728                         _(
 729                         "If you want to keep them by creating a new branch, "
 730                         "this may be a good time\nto do so with:\n\n"
 731                         " git branch new_branch_name %s\n\n"),
 732                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 733 }
 734
 735 /*
 736  * We are about to leave commit that was at the tip of a detached
 737  * HEAD.  If it is not reachable from any ref, this is the last chance
 738  * for the user to do so without resorting to reflog.
 739  */
 740 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 741 {
 742         struct rev_info revs;
 743         struct object *object = &old->object;
 744         struct object_array refs;
 745
 746         init_revisions(&revs, NULL);
 747         setup_revisions(0, NULL, &revs, NULL);
 748
 749         object->flags &= ~UNINTERESTING;
 750         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 751
 752         for_each_ref(add_pending_uninteresting_ref, &revs);
 753         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 754
 755         refs = revs.pending;
 756         revs.leak_pending = 1;
 757
 758         if (prepare_revision_walk(&revs))
 759                 die(_("internal error in revision walk"));
 760         if (!(old->object.flags & UNINTERESTING))
 761                 suggest_reattach(old, &revs);
 762         else
 763                 describe_detached_head(_("Previous HEAD position was"), old);
 764
 765         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 766         free(refs.objects);
 767 }
 768
 769 static int switch_branches(const struct checkout_opts *opts,
 770                            struct branch_info *new)
 771 {
 772         int ret = 0;
 773         struct branch_info old;
 774         void *path_to_free;
 775         unsigned char rev[20];
 776         int flag, writeout_error = 0;
 777         memset(&old, 0, sizeof(old));
 778         old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 779         old.commit = lookup_commit_reference_gently(rev, 1);
 780         if (!(flag & REF_ISSYMREF))
 781                 old.path = NULL;
 782
 783         if (old.path)
 784                 skip_prefix(old.path, "refs/heads/", &old.name);
 785
 786         if (!new->name) {
 787                 new->name = "HEAD";
 788                 new->commit = old.commit;
 789                 if (!new->commit)
 790                         die(_("You are on a branch yet to be born"));
 791                 parse_commit_or_die(new->commit);
 792         }
 793
 794         ret = merge_working_tree(opts, &old, new, &writeout_error);
 795         if (ret) {
 796                 free(path_to_free);
 797                 return ret;
 798         }
 799
 800         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 801                 orphaned_commit_warning(old.commit, new->commit);
 802
 803         update_refs_for_switch(opts, &old, new);
 804
 805         ret = post_checkout_hook(old.commit, new->commit, 1);
 806         free(path_to_free);
 807         return ret || writeout_error;
 808 }
 809
 810 static int git_checkout_config(const char *var, const char *value, void *cb)
 811 {
 812         if (!strcmp(var, "diff.ignoresubmodules")) {
 813                 struct checkout_opts *opts = cb;
 814                 handle_ignore_submodules_arg(&opts->diff_options, value);
 815                 return 0;
 816         }
 817
 818         if (starts_with(var, "submodule."))
 819                 return parse_submodule_config_option(var, value);
 820
 821         return git_xmerge_config(var, value, NULL);
 822 }
 823
 824 struct tracking_name_data {
 825         /* const */ char *src_ref;
 826         char *dst_ref;
 827         unsigned char *dst_sha1;
 828         int unique;
 829 };
 830
 831 static int check_tracking_name(struct remote *remote, void *cb_data)
 832 {
 833         struct tracking_name_data *cb = cb_data;
 834         struct refspec query;
 835         memset(&query, 0, sizeof(struct refspec));
 836         query.src = cb->src_ref;
 837         if (remote_find_tracking(remote, &query) ||
 838             get_sha1(query.dst, cb->dst_sha1)) {
 839                 free(query.dst);
 840                 return 0;
 841         }
 842         if (cb->dst_ref) {
 843                 free(query.dst);
 844                 cb->unique = 0;
 845                 return 0;
 846         }
 847         cb->dst_ref = query.dst;
 848         return 0;
 849 }
 850
 851 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 852 {
 853         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 854         char src_ref[PATH_MAX];
 855         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 856         cb_data.src_ref = src_ref;
 857         cb_data.dst_sha1 = sha1;
 858         for_each_remote(check_tracking_name, &cb_data);
 859         if (cb_data.unique)
 860                 return cb_data.dst_ref;
 861         free(cb_data.dst_ref);
 862         return NULL;
 863 }
 864
 865 static int parse_branchname_arg(int argc, const char **argv,
 866                                 int dwim_new_local_branch_ok,
 867                                 struct branch_info *new,
 868                                 struct tree **source_tree,
 869                                 unsigned char rev[20],
 870                                 const char **new_branch)
 871 {
 872         int argcount = 0;
 873         unsigned char branch_rev[20];
 874         const char *arg;
 875         int dash_dash_pos;
 876         int has_dash_dash = 0;
 877         int i;
 878
 879         /*
 880          * case 1: git checkout <ref> -- [<paths>]
 881          *
 882          *   <ref> must be a valid tree, everything after the '--' must be
 883          *   a path.
 884          *
 885          * case 2: git checkout -- [<paths>]
 886          *
 887          *   everything after the '--' must be paths.
 888          *
 889          * case 3: git checkout <something> [--]
 890          *
 891          *   (a) If <something> is a commit, that is to
 892          *       switch to the branch or detach HEAD at it.  As a special case,
 893          *       if <something> is A...B (missing A or B means HEAD but you can
 894          *       omit at most one side), and if there is a unique merge base
 895          *       between A and B, A...B names that merge base.
 896          *
 897          *   (b) If <something> is _not_ a commit, either "--" is present
 898          *       or <something> is not a path, no -t or -b was given, and
 899          *       and there is a tracking branch whose name is <something>
 900          *       in one and only one remote, then this is a short-hand to
 901          *       fork local <something> from that remote-tracking branch.
 902          *
 903          *   (c) Otherwise, if "--" is present, treat it like case (1).
 904          *
 905          *   (d) Otherwise :
 906          *       - if it's a reference, treat it like case (1)
 907          *       - else if it's a path, treat it like case (2)
 908          *       - else: fail.
 909          *
 910          * case 4: git checkout <something> <paths>
 911          *
 912          *   The first argument must not be ambiguous.
 913          *   - If it's *only* a reference, treat it like case (1).
 914          *   - If it's only a path, treat it like case (2).
 915          *   - else: fail.
 916          *
 917          */
 918         if (!argc)
 919                 return 0;
 920
 921         arg = argv[0];
 922         dash_dash_pos = -1;
 923         for (i = 0; i < argc; i++) {
 924                 if (!strcmp(argv[i], "--")) {
 925                         dash_dash_pos = i;
 926                         break;
 927                 }
 928         }
 929         if (dash_dash_pos == 0)
 930                 return 1; /* case (2) */
 931         else if (dash_dash_pos == 1)
 932                 has_dash_dash = 1; /* case (3) or (1) */
 933         else if (dash_dash_pos >= 2)
 934                 die(_("only one reference expected, %d given."), dash_dash_pos);
 935
 936         if (!strcmp(arg, "-"))
 937                 arg = "@{-1}";
 938
 939         if (get_sha1_mb(arg, rev)) {
 940                 /*
 941                  * Either case (3) or (4), with <something> not being
 942                  * a commit, or an attempt to use case (1) with an
 943                  * invalid ref.
 944                  *
 945                  * It's likely an error, but we need to find out if
 946                  * we should auto-create the branch, case (3).(b).
 947                  */
 948                 int recover_with_dwim = dwim_new_local_branch_ok;
 949
 950                 if (check_filename(NULL, arg) && !has_dash_dash)
 951                         recover_with_dwim = 0;
 952                 /*
 953                  * Accept "git checkout foo" and "git checkout foo --"
 954                  * as candidates for dwim.
 955                  */
 956                 if (!(argc == 1 && !has_dash_dash) &&
 957                     !(argc == 2 && has_dash_dash))
 958                         recover_with_dwim = 0;
 959
 960                 if (recover_with_dwim) {
 961                         const char *remote = unique_tracking_name(arg, rev);
 962                         if (remote) {
 963                                 *new_branch = arg;
 964                                 arg = remote;
 965                                 /* DWIMmed to create local branch, case (3).(b) */
 966                         } else {
 967                                 recover_with_dwim = 0;
 968                         }
 969                 }
 970
 971                 if (!recover_with_dwim) {
 972                         if (has_dash_dash)
 973                                 die(_("invalid reference: %s"), arg);
 974                         return argcount;
 975                 }
 976         }
 977
 978         /* we can't end up being in (2) anymore, eat the argument */
 979         argcount++;
 980         argv++;
 981         argc--;
 982
 983         new->name = arg;
 984         setup_branch_path(new);
 985
 986         if (!check_refname_format(new->path, 0) &&
 987             !read_ref(new->path, branch_rev))
 988                 hashcpy(rev, branch_rev);
 989         else
 990                 new->path = NULL; /* not an existing branch */
 991
 992         new->commit = lookup_commit_reference_gently(rev, 1);
 993         if (!new->commit) {
 994                 /* not a commit */
 995                 *source_tree = parse_tree_indirect(rev);
 996         } else {
 997                 parse_commit_or_die(new->commit);
 998                 *source_tree = new->commit->tree;
 999         }
1000
1001         if (!*source_tree)                   /* case (1): want a tree */
1002                 die(_("reference is not a tree: %s"), arg);
1003         if (!has_dash_dash) {/* case (3).(d) -> (1) */
1004                 /*
1005                  * Do not complain the most common case
1006                  *      git checkout branch
1007                  * even if there happen to be a file called 'branch';
1008                  * it would be extremely annoying.
1009                  */
1010                 if (argc)
1011                         verify_non_filename(NULL, arg);
1012         } else {
1013                 argcount++;
1014                 argv++;
1015                 argc--;
1016         }
1017
1018         return argcount;
1019 }
1020
1021 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1022 {
1023         int status;
1024         struct strbuf branch_ref = STRBUF_INIT;
1025
1026         if (!opts->new_branch)
1027                 die(_("You are on a branch yet to be born"));
1028         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1029         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1030         strbuf_release(&branch_ref);
1031         if (!opts->quiet)
1032                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1033                         opts->new_branch);
1034         return status;
1035 }
1036
1037 static int checkout_branch(struct checkout_opts *opts,
1038                            struct branch_info *new)
1039 {
1040         if (opts->pathspec.nr)
1041                 die(_("paths cannot be used with switching branches"));
1042
1043         if (opts->patch_mode)
1044                 die(_("'%s' cannot be used with switching branches"),
1045                     "--patch");
1046
1047         if (opts->writeout_stage)
1048                 die(_("'%s' cannot be used with switching branches"),
1049                     "--ours/--theirs");
1050
1051         if (opts->force && opts->merge)
1052                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1053
1054         if (opts->force_detach && opts->new_branch)
1055                 die(_("'%s' cannot be used with '%s'"),
1056                     "--detach", "-b/-B/--orphan");
1057
1058         if (opts->new_orphan_branch) {
1059                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1060                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1061         } else if (opts->force_detach) {
1062                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1063                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1064         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1065                 opts->track = git_branch_track;
1066
1067         if (new->name && !new->commit)
1068                 die(_("Cannot switch branch to a non-commit '%s'"),
1069                     new->name);
1070
1071         if (!new->commit && opts->new_branch) {
1072                 unsigned char rev[20];
1073                 int flag;
1074
1075                 if (!read_ref_full("HEAD", 0, rev, &flag) &&
1076                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1077                         return switch_unborn_to_new_branch(opts);
1078         }
1079         return switch_branches(opts, new);
1080 }
1081
1082 int cmd_checkout(int argc, const char **argv, const char *prefix)
1083 {
1084         struct checkout_opts opts;
1085         struct branch_info new;
1086         char *conflict_style = NULL;
1087         int dwim_new_local_branch = 1;
1088         struct option options[] = {
1089                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1090                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1091                            N_("create and checkout a new branch")),
1092                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1093                            N_("create/reset and checkout a branch")),
1094                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1095                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1096                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1097                         BRANCH_TRACK_EXPLICIT),
1098                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1099                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1100                             2),
1101                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1102                             3),
1103                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1104                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1105                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1106                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1107                            N_("conflict style (merge or diff3)")),
1108                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1109                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1110                          N_("do not limit pathspecs to sparse entries only")),
1111                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1112                                 N_("second guess 'git checkout no-such-branch'")),
1113                 OPT_END(),
1114         };
1115
1116         memset(&opts, 0, sizeof(opts));
1117         memset(&new, 0, sizeof(new));
1118         opts.overwrite_ignore = 1;
1119         opts.prefix = prefix;
1120
1121         gitmodules_config();
1122         git_config(git_checkout_config, &opts);
1123
1124         opts.track = BRANCH_TRACK_UNSPECIFIED;
1125
1126         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1127                              PARSE_OPT_KEEP_DASHDASH);
1128
1129         if (conflict_style) {
1130                 opts.merge = 1; /* implied */
1131                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1132         }
1133
1134         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1135                 die(_("-b, -B and --orphan are mutually exclusive"));
1136
1137         /*
1138          * From here on, new_branch will contain the branch to be checked out,
1139          * and new_branch_force and new_orphan_branch will tell us which one of
1140          * -b/-B/--orphan is being used.
1141          */
1142         if (opts.new_branch_force)
1143                 opts.new_branch = opts.new_branch_force;
1144
1145         if (opts.new_orphan_branch)
1146                 opts.new_branch = opts.new_orphan_branch;
1147
1148         /* --track without -b/-B/--orphan should DWIM */
1149         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1150                 const char *argv0 = argv[0];
1151                 if (!argc || !strcmp(argv0, "--"))
1152                         die (_("--track needs a branch name"));
1153                 skip_prefix(argv0, "refs/", &argv0);
1154                 skip_prefix(argv0, "remotes/", &argv0);
1155                 argv0 = strchr(argv0, '/');
1156                 if (!argv0 || !argv0[1])
1157                         die (_("Missing branch name; try -b"));
1158                 opts.new_branch = argv0 + 1;
1159         }
1160
1161         /*
1162          * Extract branch name from command line arguments, so
1163          * all that is left is pathspecs.
1164          *
1165          * Handle
1166          *
1167          *  1) git checkout <tree> -- [<paths>]
1168          *  2) git checkout -- [<paths>]
1169          *  3) git checkout <something> [<paths>]
1170          *
1171          * including "last branch" syntax and DWIM-ery for names of
1172          * remote branches, erroring out for invalid or ambiguous cases.
1173          */
1174         if (argc) {
1175                 unsigned char rev[20];
1176                 int dwim_ok =
1177                         !opts.patch_mode &&
1178                         dwim_new_local_branch &&
1179                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1180                         !opts.new_branch;
1181                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1182                                              &new, &opts.source_tree,
1183                                              rev, &opts.new_branch);
1184                 argv += n;
1185                 argc -= n;
1186         }
1187
1188         if (argc) {
1189                 parse_pathspec(&opts.pathspec, 0,
1190                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1191                                prefix, argv);
1192
1193                 if (!opts.pathspec.nr)
1194                         die(_("invalid path specification"));
1195
1196                 /*
1197                  * Try to give more helpful suggestion.
1198                  * new_branch && argc > 1 will be caught later.
1199                  */
1200                 if (opts.new_branch && argc == 1)
1201                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1202                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1203                             opts.new_branch, argv[0]);
1204
1205                 if (opts.force_detach)
1206                         die(_("git checkout: --detach does not take a path argument '%s'"),
1207                             argv[0]);
1208
1209                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1210                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1211                               "checking out of the index."));
1212         }
1213
1214         if (opts.new_branch) {
1215                 struct strbuf buf = STRBUF_INIT;
1216
1217                 opts.branch_exists =
1218                         validate_new_branchname(opts.new_branch, &buf,
1219                                                 !!opts.new_branch_force,
1220                                                 !!opts.new_branch_force);
1221
1222                 strbuf_release(&buf);
1223         }
1224
1225         if (opts.patch_mode || opts.pathspec.nr)
1226                 return checkout_paths(&opts, new.name);
1227         else
1228                 return checkout_branch(&opts, &new);
1229 }