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
  41         const char *new_branch;
  42         const char *new_branch_force;
  43         const char *new_orphan_branch;
  44         int new_branch_log;
  45         enum branch_track track;
  46         struct diff_options diff_options;
  47
  48         int branch_exists;
  49         const char *prefix;
  50         struct pathspec pathspec;
  51         struct tree *source_tree;
  52 };
  53
  54 static int post_checkout_hook(struct commit *old, struct commit *new,
  55                               int changed)
  56 {
  57         return run_hook_le(NULL, "post-checkout",
  58                            sha1_to_hex(old ? old->object.sha1 : null_sha1),
  59                            sha1_to_hex(new ? new->object.sha1 : null_sha1),
  60                            changed ? "1" : "0", NULL);
  61         /* "new" can be NULL when checking out from the index before
  62            a commit exists. */
  63
  64 }
  65
  66 static int update_some(const unsigned char *sha1, struct strbuf *base,
  67                 const char *pathname, unsigned mode, int stage, void *context)
  68 {
  69         int len;
  70         struct cache_entry *ce;
  71         int pos;
  72
  73         if (S_ISDIR(mode))
  74                 return READ_TREE_RECURSIVE;
  75
  76         len = base->len + strlen(pathname);
  77         ce = xcalloc(1, cache_entry_size(len));
  78         hashcpy(ce->sha1, sha1);
  79         memcpy(ce->name, base->buf, base->len);
  80         memcpy(ce->name + base->len, pathname, len - base->len);
  81         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  82         ce->ce_namelen = len;
  83         ce->ce_mode = create_ce_mode(mode);
  84
  85         /*
  86          * If the entry is the same as the current index, we can leave the old
  87          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  88          * do the right thing.
  89          */
  90         pos = cache_name_pos(ce->name, ce->ce_namelen);
  91         if (pos >= 0) {
  92                 struct cache_entry *old = active_cache[pos];
  93                 if (ce->ce_mode == old->ce_mode &&
  94                     !hashcmp(ce->sha1, old->sha1)) {
  95                         old->ce_flags |= CE_UPDATE;
  96                         free(ce);
  97                         return 0;
  98                 }
  99         }
 100
 101         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 102         return 0;
 103 }
 104
 105 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 106 {
 107         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 108
 109         /* update the index with the given tree's info
 110          * for all args, expanding wildcards, and exit
 111          * with any non-zero return code.
 112          */
 113         return 0;
 114 }
 115
 116 static int skip_same_name(const struct cache_entry *ce, int pos)
 117 {
 118         while (++pos < active_nr &&
 119                !strcmp(active_cache[pos]->name, ce->name))
 120                 ; /* skip */
 121         return pos;
 122 }
 123
 124 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 125 {
 126         while (pos < active_nr &&
 127                !strcmp(active_cache[pos]->name, ce->name)) {
 128                 if (ce_stage(active_cache[pos]) == stage)
 129                         return 0;
 130                 pos++;
 131         }
 132         if (stage == 2)
 133                 return error(_("path '%s' does not have our version"), ce->name);
 134         else
 135                 return error(_("path '%s' does not have their version"), ce->name);
 136 }
 137
 138 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 139 {
 140         unsigned seen = 0;
 141         const char *name = ce->name;
 142
 143         while (pos < active_nr) {
 144                 ce = active_cache[pos];
 145                 if (strcmp(name, ce->name))
 146                         break;
 147                 seen |= (1 << ce_stage(ce));
 148                 pos++;
 149         }
 150         if ((stages & seen) != stages)
 151                 return error(_("path '%s' does not have all necessary versions"),
 152                              name);
 153         return 0;
 154 }
 155
 156 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 157                           struct checkout *state)
 158 {
 159         while (pos < active_nr &&
 160                !strcmp(active_cache[pos]->name, ce->name)) {
 161                 if (ce_stage(active_cache[pos]) == stage)
 162                         return checkout_entry(active_cache[pos], state, NULL);
 163                 pos++;
 164         }
 165         if (stage == 2)
 166                 return error(_("path '%s' does not have our version"), ce->name);
 167         else
 168                 return error(_("path '%s' does not have their version"), ce->name);
 169 }
 170
 171 static int checkout_merged(int pos, struct checkout *state)
 172 {
 173         struct cache_entry *ce = active_cache[pos];
 174         const char *path = ce->name;
 175         mmfile_t ancestor, ours, theirs;
 176         int status;
 177         unsigned char sha1[20];
 178         mmbuffer_t result_buf;
 179         unsigned char threeway[3][20];
 180         unsigned mode = 0;
 181
 182         memset(threeway, 0, sizeof(threeway));
 183         while (pos < active_nr) {
 184                 int stage;
 185                 stage = ce_stage(ce);
 186                 if (!stage || strcmp(path, ce->name))
 187                         break;
 188                 hashcpy(threeway[stage - 1], ce->sha1);
 189                 if (stage == 2)
 190                         mode = create_ce_mode(ce->ce_mode);
 191                 pos++;
 192                 ce = active_cache[pos];
 193         }
 194         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
 195                 return error(_("path '%s' does not have necessary versions"), path);
 196
 197         read_mmblob(&ancestor, threeway[0]);
 198         read_mmblob(&ours, threeway[1]);
 199         read_mmblob(&theirs, threeway[2]);
 200
 201         /*
 202          * NEEDSWORK: re-create conflicts from merges with
 203          * merge.renormalize set, too
 204          */
 205         status = ll_merge(&result_buf, path, &ancestor, "base",
 206                           &ours, "ours", &theirs, "theirs", NULL);
 207         free(ancestor.ptr);
 208         free(ours.ptr);
 209         free(theirs.ptr);
 210         if (status < 0 || !result_buf.ptr) {
 211                 free(result_buf.ptr);
 212                 return error(_("path '%s': cannot merge"), path);
 213         }
 214
 215         /*
 216          * NEEDSWORK:
 217          * There is absolutely no reason to write this as a blob object
 218          * and create a phony cache entry just to leak.  This hack is
 219          * primarily to get to the write_entry() machinery that massages
 220          * the contents to work-tree format and writes out which only
 221          * allows it for a cache entry.  The code in write_entry() needs
 222          * to be refactored to allow us to feed a <buffer, size, mode>
 223          * instead of a cache entry.  Such a refactoring would help
 224          * merge_recursive as well (it also writes the merge result to the
 225          * object database even when it may contain conflicts).
 226          */
 227         if (write_sha1_file(result_buf.ptr, result_buf.size,
 228                             blob_type, sha1))
 229                 die(_("Unable to add merge result for '%s'"), path);
 230         ce = make_cache_entry(mode, sha1, path, 2, 0);
 231         if (!ce)
 232                 die(_("make_cache_entry failed for path '%s'"), path);
 233         status = checkout_entry(ce, state, NULL);
 234         return status;
 235 }
 236
 237 static int checkout_paths(const struct checkout_opts *opts,
 238                           const char *revision)
 239 {
 240         int pos;
 241         struct checkout state;
 242         static char *ps_matched;
 243         unsigned char rev[20];
 244         int flag;
 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, 1);
 278         if (read_cache_preload(&opts->pathspec) < 0)
 279                 return error(_("corrupt index file"));
 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         memset(&state, 0, sizeof(state));
 356         state.force = 1;
 357         state.refresh_cache = 1;
 358         state.istate = &the_index;
 359         for (pos = 0; pos < active_nr; pos++) {
 360                 struct cache_entry *ce = active_cache[pos];
 361                 if (ce->ce_flags & CE_MATCHED) {
 362                         if (!ce_stage(ce)) {
 363                                 errs |= checkout_entry(ce, &state, NULL);
 364                                 continue;
 365                         }
 366                         if (opts->writeout_stage)
 367                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 368                         else if (opts->merge)
 369                                 errs |= checkout_merged(pos, &state);
 370                         pos = skip_same_name(ce, pos) - 1;
 371                 }
 372         }
 373
 374         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 375                 die(_("unable to write new index file"));
 376
 377         read_ref_full("HEAD", 0, rev, &flag);
 378         head = lookup_commit_reference_gently(rev, 1);
 379
 380         errs |= post_checkout_hook(head, head, 0);
 381         return errs;
 382 }
 383
 384 static void show_local_changes(struct object *head,
 385                                const struct diff_options *opts)
 386 {
 387         struct rev_info rev;
 388         /* I think we want full paths, even if we're in a subdirectory. */
 389         init_revisions(&rev, NULL);
 390         rev.diffopt.flags = opts->flags;
 391         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 392         diff_setup_done(&rev.diffopt);
 393         add_pending_object(&rev, head, NULL);
 394         run_diff_index(&rev, 0);
 395 }
 396
 397 static void describe_detached_head(const char *msg, struct commit *commit)
 398 {
 399         struct strbuf sb = STRBUF_INIT;
 400         if (!parse_commit(commit))
 401                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 402         fprintf(stderr, "%s %s... %s\n", msg,
 403                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 404         strbuf_release(&sb);
 405 }
 406
 407 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 408                       int worktree, int *writeout_error)
 409 {
 410         struct unpack_trees_options opts;
 411         struct tree_desc tree_desc;
 412
 413         memset(&opts, 0, sizeof(opts));
 414         opts.head_idx = -1;
 415         opts.update = worktree;
 416         opts.skip_unmerged = !worktree;
 417         opts.reset = 1;
 418         opts.merge = 1;
 419         opts.fn = oneway_merge;
 420         opts.verbose_update = !o->quiet && isatty(2);
 421         opts.src_index = &the_index;
 422         opts.dst_index = &the_index;
 423         parse_tree(tree);
 424         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 425         switch (unpack_trees(1, &tree_desc, &opts)) {
 426         case -2:
 427                 *writeout_error = 1;
 428                 /*
 429                  * We return 0 nevertheless, as the index is all right
 430                  * and more importantly we have made best efforts to
 431                  * update paths in the work tree, and we cannot revert
 432                  * them.
 433                  */
 434         case 0:
 435                 return 0;
 436         default:
 437                 return 128;
 438         }
 439 }
 440
 441 struct branch_info {
 442         const char *name; /* The short name used */
 443         const char *path; /* The full name of a real branch */
 444         struct commit *commit; /* The named commit */
 445         /*
 446          * if not null the branch is detached because it's already
 447          * checked out in this checkout
 448          */
 449         char *checkout;
 450 };
 451
 452 static void setup_branch_path(struct branch_info *branch)
 453 {
 454         struct strbuf buf = STRBUF_INIT;
 455
 456         strbuf_branchname(&buf, branch->name);
 457         if (strcmp(buf.buf, branch->name))
 458                 branch->name = xstrdup(buf.buf);
 459         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 460         branch->path = strbuf_detach(&buf, NULL);
 461 }
 462
 463 static int merge_working_tree(const struct checkout_opts *opts,
 464                               struct branch_info *old,
 465                               struct branch_info *new,
 466                               int *writeout_error)
 467 {
 468         int ret;
 469         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 470
 471         hold_locked_index(lock_file, 1);
 472         if (read_cache_preload(NULL) < 0)
 473                 return error(_("corrupt index file"));
 474
 475         resolve_undo_clear();
 476         if (opts->force) {
 477                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 478                 if (ret)
 479                         return ret;
 480         } else {
 481                 struct tree_desc trees[2];
 482                 struct tree *tree;
 483                 struct unpack_trees_options topts;
 484
 485                 memset(&topts, 0, sizeof(topts));
 486                 topts.head_idx = -1;
 487                 topts.src_index = &the_index;
 488                 topts.dst_index = &the_index;
 489
 490                 setup_unpack_trees_porcelain(&topts, "checkout");
 491
 492                 refresh_cache(REFRESH_QUIET);
 493
 494                 if (unmerged_cache()) {
 495                         error(_("you need to resolve your current index first"));
 496                         return 1;
 497                 }
 498
 499                 /* 2-way merge to the new branch */
 500                 topts.initial_checkout = is_cache_unborn();
 501                 topts.update = 1;
 502                 topts.merge = 1;
 503                 topts.gently = opts->merge && old->commit;
 504                 topts.verbose_update = !opts->quiet && isatty(2);
 505                 topts.fn = twoway_merge;
 506                 if (opts->overwrite_ignore) {
 507                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 508                         topts.dir->flags |= DIR_SHOW_IGNORED;
 509                         setup_standard_excludes(topts.dir);
 510                 }
 511                 tree = parse_tree_indirect(old->commit ?
 512                                            old->commit->object.sha1 :
 513                                            EMPTY_TREE_SHA1_BIN);
 514                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 515                 tree = parse_tree_indirect(new->commit->object.sha1);
 516                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 517
 518                 ret = unpack_trees(2, trees, &topts);
 519                 if (ret == -1) {
 520                         /*
 521                          * Unpack couldn't do a trivial merge; either
 522                          * give up or do a real merge, depending on
 523                          * whether the merge flag was used.
 524                          */
 525                         struct tree *result;
 526                         struct tree *work;
 527                         struct merge_options o;
 528                         if (!opts->merge)
 529                                 return 1;
 530
 531                         /*
 532                          * Without old->commit, the below is the same as
 533                          * the two-tree unpack we already tried and failed.
 534                          */
 535                         if (!old->commit)
 536                                 return 1;
 537
 538                         /* Do more real merge */
 539
 540                         /*
 541                          * We update the index fully, then write the
 542                          * tree from the index, then merge the new
 543                          * branch with the current tree, with the old
 544                          * branch as the base. Then we reset the index
 545                          * (but not the working tree) to the new
 546                          * branch, leaving the working tree as the
 547                          * merged version, but skipping unmerged
 548                          * entries in the index.
 549                          */
 550
 551                         add_files_to_cache(NULL, NULL, 0);
 552                         /*
 553                          * NEEDSWORK: carrying over local changes
 554                          * when branches have different end-of-line
 555                          * normalization (or clean+smudge rules) is
 556                          * a pain; plumb in an option to set
 557                          * o.renormalize?
 558                          */
 559                         init_merge_options(&o);
 560                         o.verbosity = 0;
 561                         work = write_tree_from_memory(&o);
 562
 563                         ret = reset_tree(new->commit->tree, opts, 1,
 564                                          writeout_error);
 565                         if (ret)
 566                                 return ret;
 567                         o.ancestor = old->name;
 568                         o.branch1 = new->name;
 569                         o.branch2 = "local";
 570                         merge_trees(&o, new->commit->tree, work,
 571                                 old->commit->tree, &result);
 572                         ret = reset_tree(new->commit->tree, opts, 0,
 573                                          writeout_error);
 574                         if (ret)
 575                                 return ret;
 576                 }
 577         }
 578
 579         if (!active_cache_tree)
 580                 active_cache_tree = cache_tree();
 581
 582         if (!cache_tree_fully_valid(active_cache_tree))
 583                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 584
 585         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 586                 die(_("unable to write new index file"));
 587
 588         if (!opts->force && !opts->quiet)
 589                 show_local_changes(&new->commit->object, &opts->diff_options);
 590
 591         return 0;
 592 }
 593
 594 static void report_tracking(struct branch_info *new)
 595 {
 596         struct strbuf sb = STRBUF_INIT;
 597         struct branch *branch = branch_get(new->name);
 598
 599         if (!format_tracking_info(branch, &sb))
 600                 return;
 601         fputs(sb.buf, stdout);
 602         strbuf_release(&sb);
 603 }
 604
 605 static void update_refs_for_switch(const struct checkout_opts *opts,
 606                                    struct branch_info *old,
 607                                    struct branch_info *new)
 608 {
 609         struct strbuf msg = STRBUF_INIT;
 610         const char *old_desc, *reflog_msg;
 611         if (opts->new_branch) {
 612                 if (opts->new_orphan_branch) {
 613                         if (opts->new_branch_log && !log_all_ref_updates) {
 614                                 int ret;
 615                                 char *refname;
 616                                 struct strbuf err = STRBUF_INIT;
 617
 618                                 refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 619                                 ret = safe_create_reflog(refname, 1, &err);
 620                                 free(refname);
 621                                 if (ret) {
 622                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 623                                                 opts->new_orphan_branch, err.buf);
 624                                         strbuf_release(&err);
 625                                         return;
 626                                 }
 627                                 strbuf_release(&err);
 628                         }
 629                 }
 630                 else
 631                         create_branch(old->name, opts->new_branch, new->name,
 632                                       opts->new_branch_force ? 1 : 0,
 633                                       opts->new_branch_log,
 634                                       opts->new_branch_force ? 1 : 0,
 635                                       opts->quiet,
 636                                       opts->track);
 637                 new->name = opts->new_branch;
 638                 setup_branch_path(new);
 639         }
 640
 641         old_desc = old->name;
 642         if (!old_desc && old->commit)
 643                 old_desc = sha1_to_hex(old->commit->object.sha1);
 644
 645         reflog_msg = getenv("GIT_REFLOG_ACTION");
 646         if (!reflog_msg)
 647                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 648                         old_desc ? old_desc : "(invalid)", new->name);
 649         else
 650                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 651
 652         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 653                 /* Nothing to do. */
 654         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 655                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 656                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 657                 if (!opts->quiet) {
 658                         if (old->path && advice_detached_head)
 659                                 detach_advice(new->name);
 660                         describe_detached_head(_("HEAD is now at"), new->commit);
 661                 }
 662         } else if (new->path) { /* Switch branches. */
 663                 create_symref("HEAD", new->path, msg.buf);
 664                 if (!opts->quiet) {
 665                         if (old->path && !strcmp(new->path, old->path)) {
 666                                 if (opts->new_branch_force)
 667                                         fprintf(stderr, _("Reset branch '%s'\n"),
 668                                                 new->name);
 669                                 else
 670                                         fprintf(stderr, _("Already on '%s'\n"),
 671                                                 new->name);
 672                         } else if (opts->new_branch) {
 673                                 if (opts->branch_exists)
 674                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 675                                 else
 676                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 677                         } else {
 678                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 679                                         new->name);
 680                         }
 681                 }
 682                 if (old->path && old->name) {
 683                         if (!ref_exists(old->path) && reflog_exists(old->path))
 684                                 delete_reflog(old->path);
 685                 }
 686         }
 687         remove_branch_state();
 688         strbuf_release(&msg);
 689         if (!opts->quiet &&
 690             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 691                 report_tracking(new);
 692 }
 693
 694 static int add_pending_uninteresting_ref(const char *refname,
 695                                          const struct object_id *oid,
 696                                          int flags, void *cb_data)
 697 {
 698         add_pending_sha1(cb_data, refname, oid->hash, UNINTERESTING);
 699         return 0;
 700 }
 701
 702 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 703 {
 704         strbuf_addstr(sb, "  ");
 705         strbuf_addstr(sb,
 706                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 707         strbuf_addch(sb, ' ');
 708         if (!parse_commit(commit))
 709                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 710         strbuf_addch(sb, '\n');
 711 }
 712
 713 #define ORPHAN_CUTOFF 4
 714 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 715 {
 716         struct commit *c, *last = NULL;
 717         struct strbuf sb = STRBUF_INIT;
 718         int lost = 0;
 719         while ((c = get_revision(revs)) != NULL) {
 720                 if (lost < ORPHAN_CUTOFF)
 721                         describe_one_orphan(&sb, c);
 722                 last = c;
 723                 lost++;
 724         }
 725         if (ORPHAN_CUTOFF < lost) {
 726                 int more = lost - ORPHAN_CUTOFF;
 727                 if (more == 1)
 728                         describe_one_orphan(&sb, last);
 729                 else
 730                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 731         }
 732
 733         fprintf(stderr,
 734                 Q_(
 735                 /* The singular version */
 736                 "Warning: you are leaving %d commit behind, "
 737                 "not connected to\n"
 738                 "any of your branches:\n\n"
 739                 "%s\n",
 740                 /* The plural version */
 741                 "Warning: you are leaving %d commits behind, "
 742                 "not connected to\n"
 743                 "any of your branches:\n\n"
 744                 "%s\n",
 745                 /* Give ngettext() the count */
 746                 lost),
 747                 lost,
 748                 sb.buf);
 749         strbuf_release(&sb);
 750
 751         if (advice_detached_head)
 752                 fprintf(stderr,
 753                         Q_(
 754                         /* The singular version */
 755                         "If you want to keep it by creating a new branch, "
 756                         "this may be a good time\nto do so with:\n\n"
 757                         " git branch <new-branch-name> %s\n\n",
 758                         /* The plural version */
 759                         "If you want to keep them by creating a new branch, "
 760                         "this may be a good time\nto do so with:\n\n"
 761                         " git branch <new-branch-name> %s\n\n",
 762                         /* Give ngettext() the count */
 763                         lost),
 764                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 765 }
 766
 767 /*
 768  * We are about to leave commit that was at the tip of a detached
 769  * HEAD.  If it is not reachable from any ref, this is the last chance
 770  * for the user to do so without resorting to reflog.
 771  */
 772 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 773 {
 774         struct rev_info revs;
 775         struct object *object = &old->object;
 776         struct object_array refs;
 777
 778         init_revisions(&revs, NULL);
 779         setup_revisions(0, NULL, &revs, NULL);
 780
 781         object->flags &= ~UNINTERESTING;
 782         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 783
 784         for_each_ref(add_pending_uninteresting_ref, &revs);
 785         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 786
 787         refs = revs.pending;
 788         revs.leak_pending = 1;
 789
 790         if (prepare_revision_walk(&revs))
 791                 die(_("internal error in revision walk"));
 792         if (!(old->object.flags & UNINTERESTING))
 793                 suggest_reattach(old, &revs);
 794         else
 795                 describe_detached_head(_("Previous HEAD position was"), old);
 796
 797         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 798         free(refs.objects);
 799 }
 800
 801 static int switch_branches(const struct checkout_opts *opts,
 802                            struct branch_info *new)
 803 {
 804         int ret = 0;
 805         struct branch_info old;
 806         void *path_to_free;
 807         unsigned char rev[20];
 808         int flag, writeout_error = 0;
 809         memset(&old, 0, sizeof(old));
 810         old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 811         old.commit = lookup_commit_reference_gently(rev, 1);
 812         if (!(flag & REF_ISSYMREF))
 813                 old.path = NULL;
 814
 815         if (old.path)
 816                 skip_prefix(old.path, "refs/heads/", &old.name);
 817
 818         if (!new->name) {
 819                 new->name = "HEAD";
 820                 new->commit = old.commit;
 821                 if (!new->commit)
 822                         die(_("You are on a branch yet to be born"));
 823                 parse_commit_or_die(new->commit);
 824         }
 825
 826         ret = merge_working_tree(opts, &old, new, &writeout_error);
 827         if (ret) {
 828                 free(path_to_free);
 829                 return ret;
 830         }
 831
 832         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 833                 orphaned_commit_warning(old.commit, new->commit);
 834
 835         update_refs_for_switch(opts, &old, new);
 836
 837         ret = post_checkout_hook(old.commit, new->commit, 1);
 838         free(path_to_free);
 839         return ret || writeout_error;
 840 }
 841
 842 static int git_checkout_config(const char *var, const char *value, void *cb)
 843 {
 844         if (!strcmp(var, "diff.ignoresubmodules")) {
 845                 struct checkout_opts *opts = cb;
 846                 handle_ignore_submodules_arg(&opts->diff_options, value);
 847                 return 0;
 848         }
 849
 850         if (starts_with(var, "submodule."))
 851                 return parse_submodule_config_option(var, value);
 852
 853         return git_xmerge_config(var, value, NULL);
 854 }
 855
 856 struct tracking_name_data {
 857         /* const */ char *src_ref;
 858         char *dst_ref;
 859         unsigned char *dst_sha1;
 860         int unique;
 861 };
 862
 863 static int check_tracking_name(struct remote *remote, void *cb_data)
 864 {
 865         struct tracking_name_data *cb = cb_data;
 866         struct refspec query;
 867         memset(&query, 0, sizeof(struct refspec));
 868         query.src = cb->src_ref;
 869         if (remote_find_tracking(remote, &query) ||
 870             get_sha1(query.dst, cb->dst_sha1)) {
 871                 free(query.dst);
 872                 return 0;
 873         }
 874         if (cb->dst_ref) {
 875                 free(query.dst);
 876                 cb->unique = 0;
 877                 return 0;
 878         }
 879         cb->dst_ref = query.dst;
 880         return 0;
 881 }
 882
 883 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 884 {
 885         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 886         char src_ref[PATH_MAX];
 887         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 888         cb_data.src_ref = src_ref;
 889         cb_data.dst_sha1 = sha1;
 890         for_each_remote(check_tracking_name, &cb_data);
 891         if (cb_data.unique)
 892                 return cb_data.dst_ref;
 893         free(cb_data.dst_ref);
 894         return NULL;
 895 }
 896
 897 static int parse_branchname_arg(int argc, const char **argv,
 898                                 int dwim_new_local_branch_ok,
 899                                 struct branch_info *new,
 900                                 struct checkout_opts *opts,
 901                                 unsigned char rev[20])
 902 {
 903         struct tree **source_tree = &opts->source_tree;
 904         const char **new_branch = &opts->new_branch;
 905         int argcount = 0;
 906         unsigned char branch_rev[20];
 907         const char *arg;
 908         int dash_dash_pos;
 909         int has_dash_dash = 0;
 910         int i;
 911
 912         /*
 913          * case 1: git checkout <ref> -- [<paths>]
 914          *
 915          *   <ref> must be a valid tree, everything after the '--' must be
 916          *   a path.
 917          *
 918          * case 2: git checkout -- [<paths>]
 919          *
 920          *   everything after the '--' must be paths.
 921          *
 922          * case 3: git checkout <something> [--]
 923          *
 924          *   (a) If <something> is a commit, that is to
 925          *       switch to the branch or detach HEAD at it.  As a special case,
 926          *       if <something> is A...B (missing A or B means HEAD but you can
 927          *       omit at most one side), and if there is a unique merge base
 928          *       between A and B, A...B names that merge base.
 929          *
 930          *   (b) If <something> is _not_ a commit, either "--" is present
 931          *       or <something> is not a path, no -t or -b was given, and
 932          *       and there is a tracking branch whose name is <something>
 933          *       in one and only one remote, then this is a short-hand to
 934          *       fork local <something> from that remote-tracking branch.
 935          *
 936          *   (c) Otherwise, if "--" is present, treat it like case (1).
 937          *
 938          *   (d) Otherwise :
 939          *       - if it's a reference, treat it like case (1)
 940          *       - else if it's a path, treat it like case (2)
 941          *       - else: fail.
 942          *
 943          * case 4: git checkout <something> <paths>
 944          *
 945          *   The first argument must not be ambiguous.
 946          *   - If it's *only* a reference, treat it like case (1).
 947          *   - If it's only a path, treat it like case (2).
 948          *   - else: fail.
 949          *
 950          */
 951         if (!argc)
 952                 return 0;
 953
 954         arg = argv[0];
 955         dash_dash_pos = -1;
 956         for (i = 0; i < argc; i++) {
 957                 if (!strcmp(argv[i], "--")) {
 958                         dash_dash_pos = i;
 959                         break;
 960                 }
 961         }
 962         if (dash_dash_pos == 0)
 963                 return 1; /* case (2) */
 964         else if (dash_dash_pos == 1)
 965                 has_dash_dash = 1; /* case (3) or (1) */
 966         else if (dash_dash_pos >= 2)
 967                 die(_("only one reference expected, %d given."), dash_dash_pos);
 968
 969         if (!strcmp(arg, "-"))
 970                 arg = "@{-1}";
 971
 972         if (get_sha1_mb(arg, rev)) {
 973                 /*
 974                  * Either case (3) or (4), with <something> not being
 975                  * a commit, or an attempt to use case (1) with an
 976                  * invalid ref.
 977                  *
 978                  * It's likely an error, but we need to find out if
 979                  * we should auto-create the branch, case (3).(b).
 980                  */
 981                 int recover_with_dwim = dwim_new_local_branch_ok;
 982
 983                 if (check_filename(NULL, arg) && !has_dash_dash)
 984                         recover_with_dwim = 0;
 985                 /*
 986                  * Accept "git checkout foo" and "git checkout foo --"
 987                  * as candidates for dwim.
 988                  */
 989                 if (!(argc == 1 && !has_dash_dash) &&
 990                     !(argc == 2 && has_dash_dash))
 991                         recover_with_dwim = 0;
 992
 993                 if (recover_with_dwim) {
 994                         const char *remote = unique_tracking_name(arg, rev);
 995                         if (remote) {
 996                                 *new_branch = arg;
 997                                 arg = remote;
 998                                 /* DWIMmed to create local branch, case (3).(b) */
 999                         } else {
1000                                 recover_with_dwim = 0;
1001                         }
1002                 }
1003
1004                 if (!recover_with_dwim) {
1005                         if (has_dash_dash)
1006                                 die(_("invalid reference: %s"), arg);
1007                         return argcount;
1008                 }
1009         }
1010
1011         /* we can't end up being in (2) anymore, eat the argument */
1012         argcount++;
1013         argv++;
1014         argc--;
1015
1016         new->name = arg;
1017         setup_branch_path(new);
1018
1019         if (!check_refname_format(new->path, 0) &&
1020             !read_ref(new->path, branch_rev))
1021                 hashcpy(rev, branch_rev);
1022         else
1023                 new->path = NULL; /* not an existing branch */
1024
1025         new->commit = lookup_commit_reference_gently(rev, 1);
1026         if (!new->commit) {
1027                 /* not a commit */
1028                 *source_tree = parse_tree_indirect(rev);
1029         } else {
1030                 parse_commit_or_die(new->commit);
1031                 *source_tree = new->commit->tree;
1032         }
1033
1034         if (!*source_tree)                   /* case (1): want a tree */
1035                 die(_("reference is not a tree: %s"), arg);
1036         if (!has_dash_dash) {/* case (3).(d) -> (1) */
1037                 /*
1038                  * Do not complain the most common case
1039                  *      git checkout branch
1040                  * even if there happen to be a file called 'branch';
1041                  * it would be extremely annoying.
1042                  */
1043                 if (argc)
1044                         verify_non_filename(NULL, arg);
1045         } else {
1046                 argcount++;
1047                 argv++;
1048                 argc--;
1049         }
1050
1051         return argcount;
1052 }
1053
1054 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1055 {
1056         int status;
1057         struct strbuf branch_ref = STRBUF_INIT;
1058
1059         if (!opts->new_branch)
1060                 die(_("You are on a branch yet to be born"));
1061         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1062         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1063         strbuf_release(&branch_ref);
1064         if (!opts->quiet)
1065                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1066                         opts->new_branch);
1067         return status;
1068 }
1069
1070 static int checkout_branch(struct checkout_opts *opts,
1071                            struct branch_info *new)
1072 {
1073         if (opts->pathspec.nr)
1074                 die(_("paths cannot be used with switching branches"));
1075
1076         if (opts->patch_mode)
1077                 die(_("'%s' cannot be used with switching branches"),
1078                     "--patch");
1079
1080         if (opts->writeout_stage)
1081                 die(_("'%s' cannot be used with switching branches"),
1082                     "--ours/--theirs");
1083
1084         if (opts->force && opts->merge)
1085                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1086
1087         if (opts->force_detach && opts->new_branch)
1088                 die(_("'%s' cannot be used with '%s'"),
1089                     "--detach", "-b/-B/--orphan");
1090
1091         if (opts->new_orphan_branch) {
1092                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1093                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1094         } else if (opts->force_detach) {
1095                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1096                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1097         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1098                 opts->track = git_branch_track;
1099
1100         if (new->name && !new->commit)
1101                 die(_("Cannot switch branch to a non-commit '%s'"),
1102                     new->name);
1103
1104         if (new->path && !opts->force_detach && !opts->new_branch &&
1105             !opts->ignore_other_worktrees) {
1106                 unsigned char sha1[20];
1107                 int flag;
1108                 char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
1109                 if (head_ref &&
1110                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1111                         die_if_checked_out(new->path);
1112                 free(head_ref);
1113         }
1114
1115         if (!new->commit && opts->new_branch) {
1116                 unsigned char rev[20];
1117                 int flag;
1118
1119                 if (!read_ref_full("HEAD", 0, rev, &flag) &&
1120                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1121                         return switch_unborn_to_new_branch(opts);
1122         }
1123         return switch_branches(opts, new);
1124 }
1125
1126 int cmd_checkout(int argc, const char **argv, const char *prefix)
1127 {
1128         struct checkout_opts opts;
1129         struct branch_info new;
1130         char *conflict_style = NULL;
1131         int dwim_new_local_branch = 1;
1132         struct option options[] = {
1133                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1134                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1135                            N_("create and checkout a new branch")),
1136                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1137                            N_("create/reset and checkout a branch")),
1138                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1139                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1140                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1141                         BRANCH_TRACK_EXPLICIT),
1142                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1143                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1144                             2),
1145                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1146                             3),
1147                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1148                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1149                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1150                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1151                            N_("conflict style (merge or diff3)")),
1152                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1153                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1154                          N_("do not limit pathspecs to sparse entries only")),
1155                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1156                                 N_("second guess 'git checkout <no-such-branch>'")),
1157                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1158                          N_("do not check if another worktree is holding the given ref")),
1159                 OPT_END(),
1160         };
1161
1162         memset(&opts, 0, sizeof(opts));
1163         memset(&new, 0, sizeof(new));
1164         opts.overwrite_ignore = 1;
1165         opts.prefix = prefix;
1166
1167         gitmodules_config();
1168         git_config(git_checkout_config, &opts);
1169
1170         opts.track = BRANCH_TRACK_UNSPECIFIED;
1171
1172         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1173                              PARSE_OPT_KEEP_DASHDASH);
1174
1175         if (conflict_style) {
1176                 opts.merge = 1; /* implied */
1177                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1178         }
1179
1180         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1181                 die(_("-b, -B and --orphan are mutually exclusive"));
1182
1183         /*
1184          * From here on, new_branch will contain the branch to be checked out,
1185          * and new_branch_force and new_orphan_branch will tell us which one of
1186          * -b/-B/--orphan is being used.
1187          */
1188         if (opts.new_branch_force)
1189                 opts.new_branch = opts.new_branch_force;
1190
1191         if (opts.new_orphan_branch)
1192                 opts.new_branch = opts.new_orphan_branch;
1193
1194         /* --track without -b/-B/--orphan should DWIM */
1195         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1196                 const char *argv0 = argv[0];
1197                 if (!argc || !strcmp(argv0, "--"))
1198                         die (_("--track needs a branch name"));
1199                 skip_prefix(argv0, "refs/", &argv0);
1200                 skip_prefix(argv0, "remotes/", &argv0);
1201                 argv0 = strchr(argv0, '/');
1202                 if (!argv0 || !argv0[1])
1203                         die (_("Missing branch name; try -b"));
1204                 opts.new_branch = argv0 + 1;
1205         }
1206
1207         /*
1208          * Extract branch name from command line arguments, so
1209          * all that is left is pathspecs.
1210          *
1211          * Handle
1212          *
1213          *  1) git checkout <tree> -- [<paths>]
1214          *  2) git checkout -- [<paths>]
1215          *  3) git checkout <something> [<paths>]
1216          *
1217          * including "last branch" syntax and DWIM-ery for names of
1218          * remote branches, erroring out for invalid or ambiguous cases.
1219          */
1220         if (argc) {
1221                 unsigned char rev[20];
1222                 int dwim_ok =
1223                         !opts.patch_mode &&
1224                         dwim_new_local_branch &&
1225                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1226                         !opts.new_branch;
1227                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1228                                              &new, &opts, rev);
1229                 argv += n;
1230                 argc -= n;
1231         }
1232
1233         if (argc) {
1234                 parse_pathspec(&opts.pathspec, 0,
1235                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1236                                prefix, argv);
1237
1238                 if (!opts.pathspec.nr)
1239                         die(_("invalid path specification"));
1240
1241                 /*
1242                  * Try to give more helpful suggestion.
1243                  * new_branch && argc > 1 will be caught later.
1244                  */
1245                 if (opts.new_branch && argc == 1)
1246                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1247                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1248                             opts.new_branch, argv[0]);
1249
1250                 if (opts.force_detach)
1251                         die(_("git checkout: --detach does not take a path argument '%s'"),
1252                             argv[0]);
1253
1254                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1255                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1256                               "checking out of the index."));
1257         }
1258
1259         if (opts.new_branch) {
1260                 struct strbuf buf = STRBUF_INIT;
1261
1262                 opts.branch_exists =
1263                         validate_new_branchname(opts.new_branch, &buf,
1264                                                 !!opts.new_branch_force,
1265                                                 !!opts.new_branch_force);
1266
1267                 strbuf_release(&buf);
1268         }
1269
1270         if (opts.patch_mode || opts.pathspec.nr)
1271                 return checkout_paths(&opts, new.name);
1272         else
1273                 return checkout_branch(&opts, &new);
1274 }