git.oblomov.eu Git - git/blob - 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-config.h"
  22 #include "submodule.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         int ignore_other_worktrees;
  40         int show_progress;
  41
  42         const char *new_branch;
  43         const char *new_branch_force;
  44         const char *new_orphan_branch;
  45         int new_branch_log;
  46         enum branch_track track;
  47         struct diff_options diff_options;
  48
  49         int branch_exists;
  50         const char *prefix;
  51         struct pathspec pathspec;
  52         struct tree *source_tree;
  53 };
  54
  55 static int post_checkout_hook(struct commit *old, struct commit *new,
  56                               int changed)
  57 {
  58         return run_hook_le(NULL, "post-checkout",
  59                            oid_to_hex(old ? &old->object.oid : &null_oid),
  60                            oid_to_hex(new ? &new->object.oid : &null_oid),
  61                            changed ? "1" : "0", NULL);
  62         /* "new" can be NULL when checking out from the index before
  63            a commit exists. */
  64
  65 }
  66
  67 static int update_some(const unsigned char *sha1, struct strbuf *base,
  68                 const char *pathname, unsigned mode, int stage, void *context)
  69 {
  70         int len;
  71         struct cache_entry *ce;
  72         int pos;
  73
  74         if (S_ISDIR(mode))
  75                 return READ_TREE_RECURSIVE;
  76
  77         len = base->len + strlen(pathname);
  78         ce = xcalloc(1, cache_entry_size(len));
  79         hashcpy(ce->oid.hash, sha1);
  80         memcpy(ce->name, base->buf, base->len);
  81         memcpy(ce->name + base->len, pathname, len - base->len);
  82         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  83         ce->ce_namelen = len;
  84         ce->ce_mode = create_ce_mode(mode);
  85
  86         /*
  87          * If the entry is the same as the current index, we can leave the old
  88          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  89          * do the right thing.
  90          */
  91         pos = cache_name_pos(ce->name, ce->ce_namelen);
  92         if (pos >= 0) {
  93                 struct cache_entry *old = active_cache[pos];
  94                 if (ce->ce_mode == old->ce_mode &&
  95                     !oidcmp(&ce->oid, &old->oid)) {
  96                         old->ce_flags |= CE_UPDATE;
  97                         free(ce);
  98                         return 0;
  99                 }
 100         }
 101
 102         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 103         return 0;
 104 }
 105
 106 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 107 {
 108         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 109
 110         /* update the index with the given tree's info
 111          * for all args, expanding wildcards, and exit
 112          * with any non-zero return code.
 113          */
 114         return 0;
 115 }
 116
 117 static int skip_same_name(const struct cache_entry *ce, int pos)
 118 {
 119         while (++pos < active_nr &&
 120                !strcmp(active_cache[pos]->name, ce->name))
 121                 ; /* skip */
 122         return pos;
 123 }
 124
 125 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 126 {
 127         while (pos < active_nr &&
 128                !strcmp(active_cache[pos]->name, ce->name)) {
 129                 if (ce_stage(active_cache[pos]) == stage)
 130                         return 0;
 131                 pos++;
 132         }
 133         if (stage == 2)
 134                 return error(_("path '%s' does not have our version"), ce->name);
 135         else
 136                 return error(_("path '%s' does not have their version"), ce->name);
 137 }
 138
 139 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 140 {
 141         unsigned seen = 0;
 142         const char *name = ce->name;
 143
 144         while (pos < active_nr) {
 145                 ce = active_cache[pos];
 146                 if (strcmp(name, ce->name))
 147                         break;
 148                 seen |= (1 << ce_stage(ce));
 149                 pos++;
 150         }
 151         if ((stages & seen) != stages)
 152                 return error(_("path '%s' does not have all necessary versions"),
 153                              name);
 154         return 0;
 155 }
 156
 157 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 158                           const struct checkout *state)
 159 {
 160         while (pos < active_nr &&
 161                !strcmp(active_cache[pos]->name, ce->name)) {
 162                 if (ce_stage(active_cache[pos]) == stage)
 163                         return checkout_entry(active_cache[pos], state, NULL);
 164                 pos++;
 165         }
 166         if (stage == 2)
 167                 return error(_("path '%s' does not have our version"), ce->name);
 168         else
 169                 return error(_("path '%s' does not have their version"), ce->name);
 170 }
 171
 172 static int checkout_merged(int pos, const struct checkout *state)
 173 {
 174         struct cache_entry *ce = active_cache[pos];
 175         const char *path = ce->name;
 176         mmfile_t ancestor, ours, theirs;
 177         int status;
 178         struct object_id oid;
 179         mmbuffer_t result_buf;
 180         struct object_id threeway[3];
 181         unsigned mode = 0;
 182
 183         memset(threeway, 0, sizeof(threeway));
 184         while (pos < active_nr) {
 185                 int stage;
 186                 stage = ce_stage(ce);
 187                 if (!stage || strcmp(path, ce->name))
 188                         break;
 189                 oidcpy(&threeway[stage - 1], &ce->oid);
 190                 if (stage == 2)
 191                         mode = create_ce_mode(ce->ce_mode);
 192                 pos++;
 193                 ce = active_cache[pos];
 194         }
 195         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 196                 return error(_("path '%s' does not have necessary versions"), path);
 197
 198         read_mmblob(&ancestor, &threeway[0]);
 199         read_mmblob(&ours, &threeway[1]);
 200         read_mmblob(&theirs, &threeway[2]);
 201
 202         /*
 203          * NEEDSWORK: re-create conflicts from merges with
 204          * merge.renormalize set, too
 205          */
 206         status = ll_merge(&result_buf, path, &ancestor, "base",
 207                           &ours, "ours", &theirs, "theirs", NULL);
 208         free(ancestor.ptr);
 209         free(ours.ptr);
 210         free(theirs.ptr);
 211         if (status < 0 || !result_buf.ptr) {
 212                 free(result_buf.ptr);
 213                 return error(_("path '%s': cannot merge"), path);
 214         }
 215
 216         /*
 217          * NEEDSWORK:
 218          * There is absolutely no reason to write this as a blob object
 219          * and create a phony cache entry just to leak.  This hack is
 220          * primarily to get to the write_entry() machinery that massages
 221          * the contents to work-tree format and writes out which only
 222          * allows it for a cache entry.  The code in write_entry() needs
 223          * to be refactored to allow us to feed a <buffer, size, mode>
 224          * instead of a cache entry.  Such a refactoring would help
 225          * merge_recursive as well (it also writes the merge result to the
 226          * object database even when it may contain conflicts).
 227          */
 228         if (write_sha1_file(result_buf.ptr, result_buf.size,
 229                             blob_type, oid.hash))
 230                 die(_("Unable to add merge result for '%s'"), path);
 231         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
 232         if (!ce)
 233                 die(_("make_cache_entry failed for path '%s'"), path);
 234         status = checkout_entry(ce, state, NULL);
 235         return status;
 236 }
 237
 238 static int checkout_paths(const struct checkout_opts *opts,
 239                           const char *revision)
 240 {
 241         int pos;
 242         struct checkout state = CHECKOUT_INIT;
 243         static char *ps_matched;
 244         struct object_id rev;
 245         struct commit *head;
 246         int errs = 0;
 247         struct lock_file *lock_file;
 248
 249         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 250                 die(_("'%s' cannot be used with updating paths"), "--track");
 251
 252         if (opts->new_branch_log)
 253                 die(_("'%s' cannot be used with updating paths"), "-l");
 254
 255         if (opts->force && opts->patch_mode)
 256                 die(_("'%s' cannot be used with updating paths"), "-f");
 257
 258         if (opts->force_detach)
 259                 die(_("'%s' cannot be used with updating paths"), "--detach");
 260
 261         if (opts->merge && opts->patch_mode)
 262                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 263
 264         if (opts->force && opts->merge)
 265                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 266
 267         if (opts->new_branch)
 268                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 269                     opts->new_branch);
 270
 271         if (opts->patch_mode)
 272                 return run_add_interactive(revision, "--patch=checkout",
 273                                            &opts->pathspec);
 274
 275         lock_file = xcalloc(1, sizeof(struct lock_file));
 276
 277         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
 278         if (read_cache_preload(&opts->pathspec) < 0)
 279                 return error(_("index file corrupt"));
 280
 281         if (opts->source_tree)
 282                 read_tree_some(opts->source_tree, &opts->pathspec);
 283
 284         ps_matched = xcalloc(opts->pathspec.nr, 1);
 285
 286         /*
 287          * Make sure all pathspecs participated in locating the paths
 288          * to be checked out.
 289          */
 290         for (pos = 0; pos < active_nr; pos++) {
 291                 struct cache_entry *ce = active_cache[pos];
 292                 ce->ce_flags &= ~CE_MATCHED;
 293                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 294                         continue;
 295                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 296                         /*
 297                          * "git checkout tree-ish -- path", but this entry
 298                          * is in the original index; it will not be checked
 299                          * out to the working tree and it does not matter
 300                          * if pathspec matched this entry.  We will not do
 301                          * anything to this entry at all.
 302                          */
 303                         continue;
 304                 /*
 305                  * Either this entry came from the tree-ish we are
 306                  * checking the paths out of, or we are checking out
 307                  * of the index.
 308                  *
 309                  * If it comes from the tree-ish, we already know it
 310                  * matches the pathspec and could just stamp
 311                  * CE_MATCHED to it from update_some(). But we still
 312                  * need ps_matched and read_tree_recursive (and
 313                  * eventually tree_entry_interesting) cannot fill
 314                  * ps_matched yet. Once it can, we can avoid calling
 315                  * match_pathspec() for _all_ entries when
 316                  * opts->source_tree != NULL.
 317                  */
 318                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
 319                         ce->ce_flags |= CE_MATCHED;
 320         }
 321
 322         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 323                 free(ps_matched);
 324                 return 1;
 325         }
 326         free(ps_matched);
 327
 328         /* "checkout -m path" to recreate conflicted state */
 329         if (opts->merge)
 330                 unmerge_marked_index(&the_index);
 331
 332         /* Any unmerged paths? */
 333         for (pos = 0; pos < active_nr; pos++) {
 334                 const struct cache_entry *ce = active_cache[pos];
 335                 if (ce->ce_flags & CE_MATCHED) {
 336                         if (!ce_stage(ce))
 337                                 continue;
 338                         if (opts->force) {
 339                                 warning(_("path '%s' is unmerged"), ce->name);
 340                         } else if (opts->writeout_stage) {
 341                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 342                         } else if (opts->merge) {
 343                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 344                         } else {
 345                                 errs = 1;
 346                                 error(_("path '%s' is unmerged"), ce->name);
 347                         }
 348                         pos = skip_same_name(ce, pos) - 1;
 349                 }
 350         }
 351         if (errs)
 352                 return 1;
 353
 354         /* Now we are committed to check them out */
 355         state.force = 1;
 356         state.refresh_cache = 1;
 357         state.istate = &the_index;
 358         for (pos = 0; pos < active_nr; pos++) {
 359                 struct cache_entry *ce = active_cache[pos];
 360                 if (ce->ce_flags & CE_MATCHED) {
 361                         if (!ce_stage(ce)) {
 362                                 errs |= checkout_entry(ce, &state, NULL);
 363                                 continue;
 364                         }
 365                         if (opts->writeout_stage)
 366                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 367                         else if (opts->merge)
 368                                 errs |= checkout_merged(pos, &state);
 369                         pos = skip_same_name(ce, pos) - 1;
 370                 }
 371         }
 372
 373         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 374                 die(_("unable to write new index file"));
 375
 376         read_ref_full("HEAD", 0, rev.hash, NULL);
 377         head = lookup_commit_reference_gently(rev.hash, 1);
 378
 379         errs |= post_checkout_hook(head, head, 0);
 380         return errs;
 381 }
 382
 383 static void show_local_changes(struct object *head,
 384                                const struct diff_options *opts)
 385 {
 386         struct rev_info rev;
 387         /* I think we want full paths, even if we're in a subdirectory. */
 388         init_revisions(&rev, NULL);
 389         rev.diffopt.flags = opts->flags;
 390         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 391         diff_setup_done(&rev.diffopt);
 392         add_pending_object(&rev, head, NULL);
 393         run_diff_index(&rev, 0);
 394 }
 395
 396 static void describe_detached_head(const char *msg, struct commit *commit)
 397 {
 398         struct strbuf sb = STRBUF_INIT;
 399         if (!parse_commit(commit))
 400                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 401         fprintf(stderr, "%s %s... %s\n", msg,
 402                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
 403         strbuf_release(&sb);
 404 }
 405
 406 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 407                       int worktree, int *writeout_error)
 408 {
 409         struct unpack_trees_options opts;
 410         struct tree_desc tree_desc;
 411
 412         memset(&opts, 0, sizeof(opts));
 413         opts.head_idx = -1;
 414         opts.update = worktree;
 415         opts.skip_unmerged = !worktree;
 416         opts.reset = 1;
 417         opts.merge = 1;
 418         opts.fn = oneway_merge;
 419         opts.verbose_update = o->show_progress;
 420         opts.src_index = &the_index;
 421         opts.dst_index = &the_index;
 422         parse_tree(tree);
 423         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 424         switch (unpack_trees(1, &tree_desc, &opts)) {
 425         case -2:
 426                 *writeout_error = 1;
 427                 /*
 428                  * We return 0 nevertheless, as the index is all right
 429                  * and more importantly we have made best efforts to
 430                  * update paths in the work tree, and we cannot revert
 431                  * them.
 432                  */
 433         case 0:
 434                 return 0;
 435         default:
 436                 return 128;
 437         }
 438 }
 439
 440 struct branch_info {
 441         const char *name; /* The short name used */
 442         const char *path; /* The full name of a real branch */
 443         struct commit *commit; /* The named commit */
 444         /*
 445          * if not null the branch is detached because it's already
 446          * checked out in this checkout
 447          */
 448         char *checkout;
 449 };
 450
 451 static void setup_branch_path(struct branch_info *branch)
 452 {
 453         struct strbuf buf = STRBUF_INIT;
 454
 455         strbuf_branchname(&buf, branch->name);
 456         if (strcmp(buf.buf, branch->name))
 457                 branch->name = xstrdup(buf.buf);
 458         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 459         branch->path = strbuf_detach(&buf, NULL);
 460 }
 461
 462 static int merge_working_tree(const struct checkout_opts *opts,
 463                               struct branch_info *old,
 464                               struct branch_info *new,
 465                               int *writeout_error)
 466 {
 467         int ret;
 468         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 469
 470         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
 471         if (read_cache_preload(NULL) < 0)
 472                 return error(_("index file corrupt"));
 473
 474         resolve_undo_clear();
 475         if (opts->force) {
 476                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 477                 if (ret)
 478                         return ret;
 479         } else {
 480                 struct tree_desc trees[2];
 481                 struct tree *tree;
 482                 struct unpack_trees_options topts;
 483
 484                 memset(&topts, 0, sizeof(topts));
 485                 topts.head_idx = -1;
 486                 topts.src_index = &the_index;
 487                 topts.dst_index = &the_index;
 488
 489                 setup_unpack_trees_porcelain(&topts, "checkout");
 490
 491                 refresh_cache(REFRESH_QUIET);
 492
 493                 if (unmerged_cache()) {
 494                         error(_("you need to resolve your current index first"));
 495                         return 1;
 496                 }
 497
 498                 /* 2-way merge to the new branch */
 499                 topts.initial_checkout = is_cache_unborn();
 500                 topts.update = 1;
 501                 topts.merge = 1;
 502                 topts.gently = opts->merge && old->commit;
 503                 topts.verbose_update = opts->show_progress;
 504                 topts.fn = twoway_merge;
 505                 if (opts->overwrite_ignore) {
 506                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 507                         topts.dir->flags |= DIR_SHOW_IGNORED;
 508                         setup_standard_excludes(topts.dir);
 509                 }
 510                 tree = parse_tree_indirect(old->commit ?
 511                                            old->commit->object.oid.hash :
 512                                            EMPTY_TREE_SHA1_BIN);
 513                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 514                 tree = parse_tree_indirect(new->commit->object.oid.hash);
 515                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 516
 517                 ret = unpack_trees(2, trees, &topts);
 518                 if (ret == -1) {
 519                         /*
 520                          * Unpack couldn't do a trivial merge; either
 521                          * give up or do a real merge, depending on
 522                          * whether the merge flag was used.
 523                          */
 524                         struct tree *result;
 525                         struct tree *work;
 526                         struct merge_options o;
 527                         if (!opts->merge)
 528                                 return 1;
 529
 530                         /*
 531                          * Without old->commit, the below is the same as
 532                          * the two-tree unpack we already tried and failed.
 533                          */
 534                         if (!old->commit)
 535                                 return 1;
 536
 537                         /* Do more real merge */
 538
 539                         /*
 540                          * We update the index fully, then write the
 541                          * tree from the index, then merge the new
 542                          * branch with the current tree, with the old
 543                          * branch as the base. Then we reset the index
 544                          * (but not the working tree) to the new
 545                          * branch, leaving the working tree as the
 546                          * merged version, but skipping unmerged
 547                          * entries in the index.
 548                          */
 549
 550                         add_files_to_cache(NULL, NULL, 0);
 551                         /*
 552                          * NEEDSWORK: carrying over local changes
 553                          * when branches have different end-of-line
 554                          * normalization (or clean+smudge rules) is
 555                          * a pain; plumb in an option to set
 556                          * o.renormalize?
 557                          */
 558                         init_merge_options(&o);
 559                         o.verbosity = 0;
 560                         work = write_tree_from_memory(&o);
 561
 562                         ret = reset_tree(new->commit->tree, opts, 1,
 563                                          writeout_error);
 564                         if (ret)
 565                                 return ret;
 566                         o.ancestor = old->name;
 567                         o.branch1 = new->name;
 568                         o.branch2 = "local";
 569                         ret = merge_trees(&o, new->commit->tree, work,
 570                                 old->commit->tree, &result);
 571                         if (ret < 0)
 572                                 exit(128);
 573                         ret = reset_tree(new->commit->tree, opts, 0,
 574                                          writeout_error);
 575                         strbuf_release(&o.obuf);
 576                         if (ret)
 577                                 return ret;
 578                 }
 579         }
 580
 581         if (!active_cache_tree)
 582                 active_cache_tree = cache_tree();
 583
 584         if (!cache_tree_fully_valid(active_cache_tree))
 585                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 586
 587         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 588                 die(_("unable to write new index file"));
 589
 590         if (!opts->force && !opts->quiet)
 591                 show_local_changes(&new->commit->object, &opts->diff_options);
 592
 593         return 0;
 594 }
 595
 596 static void report_tracking(struct branch_info *new)
 597 {
 598         struct strbuf sb = STRBUF_INIT;
 599         struct branch *branch = branch_get(new->name);
 600
 601         if (!format_tracking_info(branch, &sb))
 602                 return;
 603         fputs(sb.buf, stdout);
 604         strbuf_release(&sb);
 605 }
 606
 607 static void update_refs_for_switch(const struct checkout_opts *opts,
 608                                    struct branch_info *old,
 609                                    struct branch_info *new)
 610 {
 611         struct strbuf msg = STRBUF_INIT;
 612         const char *old_desc, *reflog_msg;
 613         if (opts->new_branch) {
 614                 if (opts->new_orphan_branch) {
 615                         char *refname;
 616
 617                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 618                         if (opts->new_branch_log &&
 619                             !should_autocreate_reflog(refname)) {
 620                                 int ret;
 621                                 struct strbuf err = STRBUF_INIT;
 622
 623                                 ret = safe_create_reflog(refname, 1, &err);
 624                                 if (ret) {
 625                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 626                                                 opts->new_orphan_branch, err.buf);
 627                                         strbuf_release(&err);
 628                                         free(refname);
 629                                         return;
 630                                 }
 631                                 strbuf_release(&err);
 632                         }
 633                         free(refname);
 634                 }
 635                 else
 636                         create_branch(opts->new_branch, new->name,
 637                                       opts->new_branch_force ? 1 : 0,
 638                                       opts->new_branch_log,
 639                                       opts->new_branch_force ? 1 : 0,
 640                                       opts->quiet,
 641                                       opts->track);
 642                 new->name = opts->new_branch;
 643                 setup_branch_path(new);
 644         }
 645
 646         old_desc = old->name;
 647         if (!old_desc && old->commit)
 648                 old_desc = oid_to_hex(&old->commit->object.oid);
 649
 650         reflog_msg = getenv("GIT_REFLOG_ACTION");
 651         if (!reflog_msg)
 652                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 653                         old_desc ? old_desc : "(invalid)", new->name);
 654         else
 655                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 656
 657         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 658                 /* Nothing to do. */
 659         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 660                 update_ref(msg.buf, "HEAD", new->commit->object.oid.hash, NULL,
 661                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 662                 if (!opts->quiet) {
 663                         if (old->path &&
 664                             advice_detached_head && !opts->force_detach)
 665                                 detach_advice(new->name);
 666                         describe_detached_head(_("HEAD is now at"), new->commit);
 667                 }
 668         } else if (new->path) { /* Switch branches. */
 669                 if (create_symref("HEAD", new->path, msg.buf) < 0)
 670                         die(_("unable to update HEAD"));
 671                 if (!opts->quiet) {
 672                         if (old->path && !strcmp(new->path, old->path)) {
 673                                 if (opts->new_branch_force)
 674                                         fprintf(stderr, _("Reset branch '%s'\n"),
 675                                                 new->name);
 676                                 else
 677                                         fprintf(stderr, _("Already on '%s'\n"),
 678                                                 new->name);
 679                         } else if (opts->new_branch) {
 680                                 if (opts->branch_exists)
 681                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 682                                 else
 683                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 684                         } else {
 685                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 686                                         new->name);
 687                         }
 688                 }
 689                 if (old->path && old->name) {
 690                         if (!ref_exists(old->path) && reflog_exists(old->path))
 691                                 delete_reflog(old->path);
 692                 }
 693         }
 694         remove_branch_state();
 695         strbuf_release(&msg);
 696         if (!opts->quiet &&
 697             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 698                 report_tracking(new);
 699 }
 700
 701 static int add_pending_uninteresting_ref(const char *refname,
 702                                          const struct object_id *oid,
 703                                          int flags, void *cb_data)
 704 {
 705         add_pending_sha1(cb_data, refname, oid->hash, UNINTERESTING);
 706         return 0;
 707 }
 708
 709 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 710 {
 711         strbuf_addstr(sb, "  ");
 712         strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
 713         strbuf_addch(sb, ' ');
 714         if (!parse_commit(commit))
 715                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 716         strbuf_addch(sb, '\n');
 717 }
 718
 719 #define ORPHAN_CUTOFF 4
 720 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 721 {
 722         struct commit *c, *last = NULL;
 723         struct strbuf sb = STRBUF_INIT;
 724         int lost = 0;
 725         while ((c = get_revision(revs)) != NULL) {
 726                 if (lost < ORPHAN_CUTOFF)
 727                         describe_one_orphan(&sb, c);
 728                 last = c;
 729                 lost++;
 730         }
 731         if (ORPHAN_CUTOFF < lost) {
 732                 int more = lost - ORPHAN_CUTOFF;
 733                 if (more == 1)
 734                         describe_one_orphan(&sb, last);
 735                 else
 736                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 737         }
 738
 739         fprintf(stderr,
 740                 Q_(
 741                 /* The singular version */
 742                 "Warning: you are leaving %d commit behind, "
 743                 "not connected to\n"
 744                 "any of your branches:\n\n"
 745                 "%s\n",
 746                 /* The plural version */
 747                 "Warning: you are leaving %d commits behind, "
 748                 "not connected to\n"
 749                 "any of your branches:\n\n"
 750                 "%s\n",
 751                 /* Give ngettext() the count */
 752                 lost),
 753                 lost,
 754                 sb.buf);
 755         strbuf_release(&sb);
 756
 757         if (advice_detached_head)
 758                 fprintf(stderr,
 759                         Q_(
 760                         /* The singular version */
 761                         "If you want to keep it by creating a new branch, "
 762                         "this may be a good time\nto do so with:\n\n"
 763                         " git branch <new-branch-name> %s\n\n",
 764                         /* The plural version */
 765                         "If you want to keep them by creating a new branch, "
 766                         "this may be a good time\nto do so with:\n\n"
 767                         " git branch <new-branch-name> %s\n\n",
 768                         /* Give ngettext() the count */
 769                         lost),
 770                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
 771 }
 772
 773 /*
 774  * We are about to leave commit that was at the tip of a detached
 775  * HEAD.  If it is not reachable from any ref, this is the last chance
 776  * for the user to do so without resorting to reflog.
 777  */
 778 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 779 {
 780         struct rev_info revs;
 781         struct object *object = &old->object;
 782         struct object_array refs;
 783
 784         init_revisions(&revs, NULL);
 785         setup_revisions(0, NULL, &revs, NULL);
 786
 787         object->flags &= ~UNINTERESTING;
 788         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 789
 790         for_each_ref(add_pending_uninteresting_ref, &revs);
 791         add_pending_sha1(&revs, "HEAD", new->object.oid.hash, UNINTERESTING);
 792
 793         refs = revs.pending;
 794         revs.leak_pending = 1;
 795
 796         if (prepare_revision_walk(&revs))
 797                 die(_("internal error in revision walk"));
 798         if (!(old->object.flags & UNINTERESTING))
 799                 suggest_reattach(old, &revs);
 800         else
 801                 describe_detached_head(_("Previous HEAD position was"), old);
 802
 803         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 804         free(refs.objects);
 805 }
 806
 807 static int switch_branches(const struct checkout_opts *opts,
 808                            struct branch_info *new)
 809 {
 810         int ret = 0;
 811         struct branch_info old;
 812         void *path_to_free;
 813         struct object_id rev;
 814         int flag, writeout_error = 0;
 815         memset(&old, 0, sizeof(old));
 816         old.path = path_to_free = resolve_refdup("HEAD", 0, rev.hash, &flag);
 817         old.commit = lookup_commit_reference_gently(rev.hash, 1);
 818         if (!(flag & REF_ISSYMREF))
 819                 old.path = NULL;
 820
 821         if (old.path)
 822                 skip_prefix(old.path, "refs/heads/", &old.name);
 823
 824         if (!new->name) {
 825                 new->name = "HEAD";
 826                 new->commit = old.commit;
 827                 if (!new->commit)
 828                         die(_("You are on a branch yet to be born"));
 829                 parse_commit_or_die(new->commit);
 830         }
 831
 832         ret = merge_working_tree(opts, &old, new, &writeout_error);
 833         if (ret) {
 834                 free(path_to_free);
 835                 return ret;
 836         }
 837
 838         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 839                 orphaned_commit_warning(old.commit, new->commit);
 840
 841         update_refs_for_switch(opts, &old, new);
 842
 843         ret = post_checkout_hook(old.commit, new->commit, 1);
 844         free(path_to_free);
 845         return ret || writeout_error;
 846 }
 847
 848 static int git_checkout_config(const char *var, const char *value, void *cb)
 849 {
 850         if (!strcmp(var, "diff.ignoresubmodules")) {
 851                 struct checkout_opts *opts = cb;
 852                 handle_ignore_submodules_arg(&opts->diff_options, value);
 853                 return 0;
 854         }
 855
 856         if (starts_with(var, "submodule."))
 857                 return parse_submodule_config_option(var, value);
 858
 859         return git_xmerge_config(var, value, NULL);
 860 }
 861
 862 struct tracking_name_data {
 863         /* const */ char *src_ref;
 864         char *dst_ref;
 865         struct object_id *dst_oid;
 866         int unique;
 867 };
 868
 869 static int check_tracking_name(struct remote *remote, void *cb_data)
 870 {
 871         struct tracking_name_data *cb = cb_data;
 872         struct refspec query;
 873         memset(&query, 0, sizeof(struct refspec));
 874         query.src = cb->src_ref;
 875         if (remote_find_tracking(remote, &query) ||
 876             get_oid(query.dst, cb->dst_oid)) {
 877                 free(query.dst);
 878                 return 0;
 879         }
 880         if (cb->dst_ref) {
 881                 free(query.dst);
 882                 cb->unique = 0;
 883                 return 0;
 884         }
 885         cb->dst_ref = query.dst;
 886         return 0;
 887 }
 888
 889 static const char *unique_tracking_name(const char *name, struct object_id *oid)
 890 {
 891         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 892         char src_ref[PATH_MAX];
 893         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 894         cb_data.src_ref = src_ref;
 895         cb_data.dst_oid = oid;
 896         for_each_remote(check_tracking_name, &cb_data);
 897         if (cb_data.unique)
 898                 return cb_data.dst_ref;
 899         free(cb_data.dst_ref);
 900         return NULL;
 901 }
 902
 903 static int parse_branchname_arg(int argc, const char **argv,
 904                                 int dwim_new_local_branch_ok,
 905                                 struct branch_info *new,
 906                                 struct checkout_opts *opts,
 907                                 struct object_id *rev)
 908 {
 909         struct tree **source_tree = &opts->source_tree;
 910         const char **new_branch = &opts->new_branch;
 911         int argcount = 0;
 912         struct object_id branch_rev;
 913         const char *arg;
 914         int dash_dash_pos;
 915         int has_dash_dash = 0;
 916         int i;
 917
 918         /*
 919          * case 1: git checkout <ref> -- [<paths>]
 920          *
 921          *   <ref> must be a valid tree, everything after the '--' must be
 922          *   a path.
 923          *
 924          * case 2: git checkout -- [<paths>]
 925          *
 926          *   everything after the '--' must be paths.
 927          *
 928          * case 3: git checkout <something> [--]
 929          *
 930          *   (a) If <something> is a commit, that is to
 931          *       switch to the branch or detach HEAD at it.  As a special case,
 932          *       if <something> is A...B (missing A or B means HEAD but you can
 933          *       omit at most one side), and if there is a unique merge base
 934          *       between A and B, A...B names that merge base.
 935          *
 936          *   (b) If <something> is _not_ a commit, either "--" is present
 937          *       or <something> is not a path, no -t or -b was given, and
 938          *       and there is a tracking branch whose name is <something>
 939          *       in one and only one remote, then this is a short-hand to
 940          *       fork local <something> from that remote-tracking branch.
 941          *
 942          *   (c) Otherwise, if "--" is present, treat it like case (1).
 943          *
 944          *   (d) Otherwise :
 945          *       - if it's a reference, treat it like case (1)
 946          *       - else if it's a path, treat it like case (2)
 947          *       - else: fail.
 948          *
 949          * case 4: git checkout <something> <paths>
 950          *
 951          *   The first argument must not be ambiguous.
 952          *   - If it's *only* a reference, treat it like case (1).
 953          *   - If it's only a path, treat it like case (2).
 954          *   - else: fail.
 955          *
 956          */
 957         if (!argc)
 958                 return 0;
 959
 960         arg = argv[0];
 961         dash_dash_pos = -1;
 962         for (i = 0; i < argc; i++) {
 963                 if (!strcmp(argv[i], "--")) {
 964                         dash_dash_pos = i;
 965                         break;
 966                 }
 967         }
 968         if (dash_dash_pos == 0)
 969                 return 1; /* case (2) */
 970         else if (dash_dash_pos == 1)
 971                 has_dash_dash = 1; /* case (3) or (1) */
 972         else if (dash_dash_pos >= 2)
 973                 die(_("only one reference expected, %d given."), dash_dash_pos);
 974
 975         if (!strcmp(arg, "-"))
 976                 arg = "@{-1}";
 977
 978         if (get_oid_mb(arg, rev)) {
 979                 /*
 980                  * Either case (3) or (4), with <something> not being
 981                  * a commit, or an attempt to use case (1) with an
 982                  * invalid ref.
 983                  *
 984                  * It's likely an error, but we need to find out if
 985                  * we should auto-create the branch, case (3).(b).
 986                  */
 987                 int recover_with_dwim = dwim_new_local_branch_ok;
 988
 989                 if (!has_dash_dash &&
 990                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
 991                         recover_with_dwim = 0;
 992                 /*
 993                  * Accept "git checkout foo" and "git checkout foo --"
 994                  * as candidates for dwim.
 995                  */
 996                 if (!(argc == 1 && !has_dash_dash) &&
 997                     !(argc == 2 && has_dash_dash))
 998                         recover_with_dwim = 0;
 999
1000                 if (recover_with_dwim) {
1001                         const char *remote = unique_tracking_name(arg, rev);
1002                         if (remote) {
1003                                 *new_branch = arg;
1004                                 arg = remote;
1005                                 /* DWIMmed to create local branch, case (3).(b) */
1006                         } else {
1007                                 recover_with_dwim = 0;
1008                         }
1009                 }
1010
1011                 if (!recover_with_dwim) {
1012                         if (has_dash_dash)
1013                                 die(_("invalid reference: %s"), arg);
1014                         return argcount;
1015                 }
1016         }
1017
1018         /* we can't end up being in (2) anymore, eat the argument */
1019         argcount++;
1020         argv++;
1021         argc--;
1022
1023         new->name = arg;
1024         setup_branch_path(new);
1025
1026         if (!check_refname_format(new->path, 0) &&
1027             !read_ref(new->path, branch_rev.hash))
1028                 oidcpy(rev, &branch_rev);
1029         else
1030                 new->path = NULL; /* not an existing branch */
1031
1032         new->commit = lookup_commit_reference_gently(rev->hash, 1);
1033         if (!new->commit) {
1034                 /* not a commit */
1035                 *source_tree = parse_tree_indirect(rev->hash);
1036         } else {
1037                 parse_commit_or_die(new->commit);
1038                 *source_tree = new->commit->tree;
1039         }
1040
1041         if (!*source_tree)                   /* case (1): want a tree */
1042                 die(_("reference is not a tree: %s"), arg);
1043         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1044                 /*
1045                  * Do not complain the most common case
1046                  *      git checkout branch
1047                  * even if there happen to be a file called 'branch';
1048                  * it would be extremely annoying.
1049                  */
1050                 if (argc)
1051                         verify_non_filename(opts->prefix, arg);
1052         } else {
1053                 argcount++;
1054                 argv++;
1055                 argc--;
1056         }
1057
1058         return argcount;
1059 }
1060
1061 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1062 {
1063         int status;
1064         struct strbuf branch_ref = STRBUF_INIT;
1065
1066         if (!opts->new_branch)
1067                 die(_("You are on a branch yet to be born"));
1068         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1069         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1070         strbuf_release(&branch_ref);
1071         if (!opts->quiet)
1072                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1073                         opts->new_branch);
1074         return status;
1075 }
1076
1077 static int checkout_branch(struct checkout_opts *opts,
1078                            struct branch_info *new)
1079 {
1080         if (opts->pathspec.nr)
1081                 die(_("paths cannot be used with switching branches"));
1082
1083         if (opts->patch_mode)
1084                 die(_("'%s' cannot be used with switching branches"),
1085                     "--patch");
1086
1087         if (opts->writeout_stage)
1088                 die(_("'%s' cannot be used with switching branches"),
1089                     "--ours/--theirs");
1090
1091         if (opts->force && opts->merge)
1092                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1093
1094         if (opts->force_detach && opts->new_branch)
1095                 die(_("'%s' cannot be used with '%s'"),
1096                     "--detach", "-b/-B/--orphan");
1097
1098         if (opts->new_orphan_branch) {
1099                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1100                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1101         } else if (opts->force_detach) {
1102                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1103                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1104         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1105                 opts->track = git_branch_track;
1106
1107         if (new->name && !new->commit)
1108                 die(_("Cannot switch branch to a non-commit '%s'"),
1109                     new->name);
1110
1111         if (new->path && !opts->force_detach && !opts->new_branch &&
1112             !opts->ignore_other_worktrees) {
1113                 struct object_id oid;
1114                 int flag;
1115                 char *head_ref = resolve_refdup("HEAD", 0, oid.hash, &flag);
1116                 if (head_ref &&
1117                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1118                         die_if_checked_out(new->path, 1);
1119                 free(head_ref);
1120         }
1121
1122         if (!new->commit && opts->new_branch) {
1123                 struct object_id rev;
1124                 int flag;
1125
1126                 if (!read_ref_full("HEAD", 0, rev.hash, &flag) &&
1127                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1128                         return switch_unborn_to_new_branch(opts);
1129         }
1130         return switch_branches(opts, new);
1131 }
1132
1133 int cmd_checkout(int argc, const char **argv, const char *prefix)
1134 {
1135         struct checkout_opts opts;
1136         struct branch_info new;
1137         char *conflict_style = NULL;
1138         int dwim_new_local_branch = 1;
1139         struct option options[] = {
1140                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1141                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1142                            N_("create and checkout a new branch")),
1143                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1144                            N_("create/reset and checkout a branch")),
1145                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1146                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1147                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1148                         BRANCH_TRACK_EXPLICIT),
1149                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1150                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1151                             2),
1152                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1153                             3),
1154                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1155                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1156                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1157                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1158                            N_("conflict style (merge or diff3)")),
1159                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1160                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1161                          N_("do not limit pathspecs to sparse entries only")),
1162                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1163                                 N_("second guess 'git checkout <no-such-branch>'")),
1164                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1165                          N_("do not check if another worktree is holding the given ref")),
1166                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1167                 OPT_END(),
1168         };
1169
1170         memset(&opts, 0, sizeof(opts));
1171         memset(&new, 0, sizeof(new));
1172         opts.overwrite_ignore = 1;
1173         opts.prefix = prefix;
1174         opts.show_progress = -1;
1175
1176         gitmodules_config();
1177         git_config(git_checkout_config, &opts);
1178
1179         opts.track = BRANCH_TRACK_UNSPECIFIED;
1180
1181         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1182                              PARSE_OPT_KEEP_DASHDASH);
1183
1184         if (opts.show_progress < 0) {
1185                 if (opts.quiet)
1186                         opts.show_progress = 0;
1187                 else
1188                         opts.show_progress = isatty(2);
1189         }
1190
1191         if (conflict_style) {
1192                 opts.merge = 1; /* implied */
1193                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1194         }
1195
1196         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1197                 die(_("-b, -B and --orphan are mutually exclusive"));
1198
1199         /*
1200          * From here on, new_branch will contain the branch to be checked out,
1201          * and new_branch_force and new_orphan_branch will tell us which one of
1202          * -b/-B/--orphan is being used.
1203          */
1204         if (opts.new_branch_force)
1205                 opts.new_branch = opts.new_branch_force;
1206
1207         if (opts.new_orphan_branch)
1208                 opts.new_branch = opts.new_orphan_branch;
1209
1210         /* --track without -b/-B/--orphan should DWIM */
1211         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1212                 const char *argv0 = argv[0];
1213                 if (!argc || !strcmp(argv0, "--"))
1214                         die (_("--track needs a branch name"));
1215                 skip_prefix(argv0, "refs/", &argv0);
1216                 skip_prefix(argv0, "remotes/", &argv0);
1217                 argv0 = strchr(argv0, '/');
1218                 if (!argv0 || !argv0[1])
1219                         die (_("Missing branch name; try -b"));
1220                 opts.new_branch = argv0 + 1;
1221         }
1222
1223         /*
1224          * Extract branch name from command line arguments, so
1225          * all that is left is pathspecs.
1226          *
1227          * Handle
1228          *
1229          *  1) git checkout <tree> -- [<paths>]
1230          *  2) git checkout -- [<paths>]
1231          *  3) git checkout <something> [<paths>]
1232          *
1233          * including "last branch" syntax and DWIM-ery for names of
1234          * remote branches, erroring out for invalid or ambiguous cases.
1235          */
1236         if (argc) {
1237                 struct object_id rev;
1238                 int dwim_ok =
1239                         !opts.patch_mode &&
1240                         dwim_new_local_branch &&
1241                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1242                         !opts.new_branch;
1243                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1244                                              &new, &opts, &rev);
1245                 argv += n;
1246                 argc -= n;
1247         }
1248
1249         if (argc) {
1250                 parse_pathspec(&opts.pathspec, 0,
1251                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1252                                prefix, argv);
1253
1254                 if (!opts.pathspec.nr)
1255                         die(_("invalid path specification"));
1256
1257                 /*
1258                  * Try to give more helpful suggestion.
1259                  * new_branch && argc > 1 will be caught later.
1260                  */
1261                 if (opts.new_branch && argc == 1)
1262                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1263                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1264                             opts.new_branch, argv[0]);
1265
1266                 if (opts.force_detach)
1267                         die(_("git checkout: --detach does not take a path argument '%s'"),
1268                             argv[0]);
1269
1270                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1271                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1272                               "checking out of the index."));
1273         }
1274
1275         if (opts.new_branch) {
1276                 struct strbuf buf = STRBUF_INIT;
1277
1278                 opts.branch_exists =
1279                         validate_new_branchname(opts.new_branch, &buf,
1280                                                 !!opts.new_branch_force,
1281                                                 !!opts.new_branch_force);
1282
1283                 strbuf_release(&buf);
1284         }
1285
1286         if (opts.patch_mode || opts.pathspec.nr)
1287                 return checkout_paths(&opts, new.name);
1288         else
1289                 return checkout_branch(&opts, &new);
1290 }