git.oblomov.eu Git - git/blob - builtin/checkout.c

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