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         struct pathspec pathspec;
  50         struct tree *source_tree;
  51 };
  52
  53 static int post_checkout_hook(struct commit *old, struct commit *new,
  54                               int changed)
  55 {
  56         return run_hook(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(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, 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, 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.raw);
 270
 271         ps_matched = xcalloc(1, opts->pathspec.nr);
 272
 273         /*
 274          * Make sure all pathspecs participated in locating the paths
 275          * to be checked out.
 276          */
 277         for (pos = 0; pos < active_nr; pos++) {
 278                 struct cache_entry *ce = active_cache[pos];
 279                 ce->ce_flags &= ~CE_MATCHED;
 280                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 281                         continue;
 282                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 283                         /*
 284                          * "git checkout tree-ish -- path", but this entry
 285                          * is in the original index; it will not be checked
 286                          * out to the working tree and it does not matter
 287                          * if pathspec matched this entry.  We will not do
 288                          * anything to this entry at all.
 289                          */
 290                         continue;
 291                 /*
 292                  * Either this entry came from the tree-ish we are
 293                  * checking the paths out of, or we are checking out
 294                  * of the index.
 295                  *
 296                  * If it comes from the tree-ish, we already know it
 297                  * matches the pathspec and could just stamp
 298                  * CE_MATCHED to it from update_some(). But we still
 299                  * need ps_matched and read_tree_recursive (and
 300                  * eventually tree_entry_interesting) cannot fill
 301                  * ps_matched yet. Once it can, we can avoid calling
 302                  * match_pathspec() for _all_ entries when
 303                  * opts->source_tree != NULL.
 304                  */
 305                 if (match_pathspec_depth(&opts->pathspec, ce->name, ce_namelen(ce),
 306                                    0, ps_matched))
 307                         ce->ce_flags |= CE_MATCHED;
 308         }
 309
 310         if (report_path_error(ps_matched, opts->pathspec.raw, opts->prefix)) {
 311                 free(ps_matched);
 312                 return 1;
 313         }
 314         free(ps_matched);
 315
 316         /* "checkout -m path" to recreate conflicted state */
 317         if (opts->merge)
 318                 unmerge_marked_index(&the_index);
 319
 320         /* Any unmerged paths? */
 321         for (pos = 0; pos < active_nr; pos++) {
 322                 struct cache_entry *ce = active_cache[pos];
 323                 if (ce->ce_flags & CE_MATCHED) {
 324                         if (!ce_stage(ce))
 325                                 continue;
 326                         if (opts->force) {
 327                                 warning(_("path '%s' is unmerged"), ce->name);
 328                         } else if (stage) {
 329                                 errs |= check_stage(stage, ce, pos);
 330                         } else if (opts->merge) {
 331                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 332                         } else {
 333                                 errs = 1;
 334                                 error(_("path '%s' is unmerged"), ce->name);
 335                         }
 336                         pos = skip_same_name(ce, pos) - 1;
 337                 }
 338         }
 339         if (errs)
 340                 return 1;
 341
 342         /* Now we are committed to check them out */
 343         memset(&state, 0, sizeof(state));
 344         state.force = 1;
 345         state.refresh_cache = 1;
 346         for (pos = 0; pos < active_nr; pos++) {
 347                 struct cache_entry *ce = active_cache[pos];
 348                 if (ce->ce_flags & CE_MATCHED) {
 349                         if (!ce_stage(ce)) {
 350                                 errs |= checkout_entry(ce, &state, NULL);
 351                                 continue;
 352                         }
 353                         if (stage)
 354                                 errs |= checkout_stage(stage, ce, pos, &state);
 355                         else if (merge)
 356                                 errs |= checkout_merged(pos, &state);
 357                         pos = skip_same_name(ce, pos) - 1;
 358                 }
 359         }
 360
 361         if (write_cache(newfd, active_cache, active_nr) ||
 362             commit_locked_index(lock_file))
 363                 die(_("unable to write new index file"));
 364
 365         read_ref_full("HEAD", rev, 0, &flag);
 366         head = lookup_commit_reference_gently(rev, 1);
 367
 368         errs |= post_checkout_hook(head, head, 0);
 369         return errs;
 370 }
 371
 372 static void show_local_changes(struct object *head,
 373                                const struct diff_options *opts)
 374 {
 375         struct rev_info rev;
 376         /* I think we want full paths, even if we're in a subdirectory. */
 377         init_revisions(&rev, NULL);
 378         rev.diffopt.flags = opts->flags;
 379         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 380         diff_setup_done(&rev.diffopt);
 381         add_pending_object(&rev, head, NULL);
 382         run_diff_index(&rev, 0);
 383 }
 384
 385 static void describe_detached_head(const char *msg, struct commit *commit)
 386 {
 387         struct strbuf sb = STRBUF_INIT;
 388         parse_commit(commit);
 389         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 390         fprintf(stderr, "%s %s... %s\n", msg,
 391                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 392         strbuf_release(&sb);
 393 }
 394
 395 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 396                       int worktree, int *writeout_error)
 397 {
 398         struct unpack_trees_options opts;
 399         struct tree_desc tree_desc;
 400
 401         memset(&opts, 0, sizeof(opts));
 402         opts.head_idx = -1;
 403         opts.update = worktree;
 404         opts.skip_unmerged = !worktree;
 405         opts.reset = 1;
 406         opts.merge = 1;
 407         opts.fn = oneway_merge;
 408         opts.verbose_update = !o->quiet && isatty(2);
 409         opts.src_index = &the_index;
 410         opts.dst_index = &the_index;
 411         parse_tree(tree);
 412         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 413         switch (unpack_trees(1, &tree_desc, &opts)) {
 414         case -2:
 415                 *writeout_error = 1;
 416                 /*
 417                  * We return 0 nevertheless, as the index is all right
 418                  * and more importantly we have made best efforts to
 419                  * update paths in the work tree, and we cannot revert
 420                  * them.
 421                  */
 422         case 0:
 423                 return 0;
 424         default:
 425                 return 128;
 426         }
 427 }
 428
 429 struct branch_info {
 430         const char *name; /* The short name used */
 431         const char *path; /* The full name of a real branch */
 432         struct commit *commit; /* The named commit */
 433 };
 434
 435 static void setup_branch_path(struct branch_info *branch)
 436 {
 437         struct strbuf buf = STRBUF_INIT;
 438
 439         strbuf_branchname(&buf, branch->name);
 440         if (strcmp(buf.buf, branch->name))
 441                 branch->name = xstrdup(buf.buf);
 442         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 443         branch->path = strbuf_detach(&buf, NULL);
 444 }
 445
 446 static int merge_working_tree(const struct checkout_opts *opts,
 447                               struct branch_info *old,
 448                               struct branch_info *new,
 449                               int *writeout_error)
 450 {
 451         int ret;
 452         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 453         int newfd = hold_locked_index(lock_file, 1);
 454
 455         if (read_cache_preload(NULL) < 0)
 456                 return error(_("corrupt index file"));
 457
 458         resolve_undo_clear();
 459         if (opts->force) {
 460                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 461                 if (ret)
 462                         return ret;
 463         } else {
 464                 struct tree_desc trees[2];
 465                 struct tree *tree;
 466                 struct unpack_trees_options topts;
 467
 468                 memset(&topts, 0, sizeof(topts));
 469                 topts.head_idx = -1;
 470                 topts.src_index = &the_index;
 471                 topts.dst_index = &the_index;
 472
 473                 setup_unpack_trees_porcelain(&topts, "checkout");
 474
 475                 refresh_cache(REFRESH_QUIET);
 476
 477                 if (unmerged_cache()) {
 478                         error(_("you need to resolve your current index first"));
 479                         return 1;
 480                 }
 481
 482                 /* 2-way merge to the new branch */
 483                 topts.initial_checkout = is_cache_unborn();
 484                 topts.update = 1;
 485                 topts.merge = 1;
 486                 topts.gently = opts->merge && old->commit;
 487                 topts.verbose_update = !opts->quiet && isatty(2);
 488                 topts.fn = twoway_merge;
 489                 if (opts->overwrite_ignore) {
 490                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 491                         topts.dir->flags |= DIR_SHOW_IGNORED;
 492                         setup_standard_excludes(topts.dir);
 493                 }
 494                 tree = parse_tree_indirect(old->commit ?
 495                                            old->commit->object.sha1 :
 496                                            EMPTY_TREE_SHA1_BIN);
 497                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 498                 tree = parse_tree_indirect(new->commit->object.sha1);
 499                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 500
 501                 ret = unpack_trees(2, trees, &topts);
 502                 if (ret == -1) {
 503                         /*
 504                          * Unpack couldn't do a trivial merge; either
 505                          * give up or do a real merge, depending on
 506                          * whether the merge flag was used.
 507                          */
 508                         struct tree *result;
 509                         struct tree *work;
 510                         struct merge_options o;
 511                         if (!opts->merge)
 512                                 return 1;
 513
 514                         /*
 515                          * Without old->commit, the below is the same as
 516                          * the two-tree unpack we already tried and failed.
 517                          */
 518                         if (!old->commit)
 519                                 return 1;
 520
 521                         /* Do more real merge */
 522
 523                         /*
 524                          * We update the index fully, then write the
 525                          * tree from the index, then merge the new
 526                          * branch with the current tree, with the old
 527                          * branch as the base. Then we reset the index
 528                          * (but not the working tree) to the new
 529                          * branch, leaving the working tree as the
 530                          * merged version, but skipping unmerged
 531                          * entries in the index.
 532                          */
 533
 534                         add_files_to_cache(NULL, NULL, 0);
 535                         /*
 536                          * NEEDSWORK: carrying over local changes
 537                          * when branches have different end-of-line
 538                          * normalization (or clean+smudge rules) is
 539                          * a pain; plumb in an option to set
 540                          * o.renormalize?
 541                          */
 542                         init_merge_options(&o);
 543                         o.verbosity = 0;
 544                         work = write_tree_from_memory(&o);
 545
 546                         ret = reset_tree(new->commit->tree, opts, 1,
 547                                          writeout_error);
 548                         if (ret)
 549                                 return ret;
 550                         o.ancestor = old->name;
 551                         o.branch1 = new->name;
 552                         o.branch2 = "local";
 553                         merge_trees(&o, new->commit->tree, work,
 554                                 old->commit->tree, &result);
 555                         ret = reset_tree(new->commit->tree, opts, 0,
 556                                          writeout_error);
 557                         if (ret)
 558                                 return ret;
 559                 }
 560         }
 561
 562         if (write_cache(newfd, active_cache, active_nr) ||
 563             commit_locked_index(lock_file))
 564                 die(_("unable to write new index file"));
 565
 566         if (!opts->force && !opts->quiet)
 567                 show_local_changes(&new->commit->object, &opts->diff_options);
 568
 569         return 0;
 570 }
 571
 572 static void report_tracking(struct branch_info *new)
 573 {
 574         struct strbuf sb = STRBUF_INIT;
 575         struct branch *branch = branch_get(new->name);
 576
 577         if (!format_tracking_info(branch, &sb))
 578                 return;
 579         fputs(sb.buf, stdout);
 580         strbuf_release(&sb);
 581 }
 582
 583 static void update_refs_for_switch(const struct checkout_opts *opts,
 584                                    struct branch_info *old,
 585                                    struct branch_info *new)
 586 {
 587         struct strbuf msg = STRBUF_INIT;
 588         const char *old_desc, *reflog_msg;
 589         if (opts->new_branch) {
 590                 if (opts->new_orphan_branch) {
 591                         if (opts->new_branch_log && !log_all_ref_updates) {
 592                                 int temp;
 593                                 char log_file[PATH_MAX];
 594                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 595
 596                                 temp = log_all_ref_updates;
 597                                 log_all_ref_updates = 1;
 598                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 599                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 600                                             opts->new_orphan_branch);
 601                                         log_all_ref_updates = temp;
 602                                         return;
 603                                 }
 604                                 log_all_ref_updates = temp;
 605                         }
 606                 }
 607                 else
 608                         create_branch(old->name, opts->new_branch, new->name,
 609                                       opts->new_branch_force ? 1 : 0,
 610                                       opts->new_branch_log,
 611                                       opts->new_branch_force ? 1 : 0,
 612                                       opts->quiet,
 613                                       opts->track);
 614                 new->name = opts->new_branch;
 615                 setup_branch_path(new);
 616         }
 617
 618         old_desc = old->name;
 619         if (!old_desc && old->commit)
 620                 old_desc = sha1_to_hex(old->commit->object.sha1);
 621
 622         reflog_msg = getenv("GIT_REFLOG_ACTION");
 623         if (!reflog_msg)
 624                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 625                         old_desc ? old_desc : "(invalid)", new->name);
 626         else
 627                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 628
 629         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 630                 /* Nothing to do. */
 631         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 632                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 633                            REF_NODEREF, DIE_ON_ERR);
 634                 if (!opts->quiet) {
 635                         if (old->path && advice_detached_head)
 636                                 detach_advice(new->name);
 637                         describe_detached_head(_("HEAD is now at"), new->commit);
 638                 }
 639         } else if (new->path) { /* Switch branches. */
 640                 create_symref("HEAD", new->path, msg.buf);
 641                 if (!opts->quiet) {
 642                         if (old->path && !strcmp(new->path, old->path)) {
 643                                 if (opts->new_branch_force)
 644                                         fprintf(stderr, _("Reset branch '%s'\n"),
 645                                                 new->name);
 646                                 else
 647                                         fprintf(stderr, _("Already on '%s'\n"),
 648                                                 new->name);
 649                         } else if (opts->new_branch) {
 650                                 if (opts->branch_exists)
 651                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 652                                 else
 653                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 654                         } else {
 655                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 656                                         new->name);
 657                         }
 658                 }
 659                 if (old->path && old->name) {
 660                         char log_file[PATH_MAX], ref_file[PATH_MAX];
 661
 662                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
 663                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
 664                         if (!file_exists(ref_file) && file_exists(log_file))
 665                                 remove_path(log_file);
 666                 }
 667         }
 668         remove_branch_state();
 669         strbuf_release(&msg);
 670         if (!opts->quiet &&
 671             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 672                 report_tracking(new);
 673 }
 674
 675 static int add_pending_uninteresting_ref(const char *refname,
 676                                          const unsigned char *sha1,
 677                                          int flags, void *cb_data)
 678 {
 679         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 680         return 0;
 681 }
 682
 683 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 684 {
 685         parse_commit(commit);
 686         strbuf_addstr(sb, "  ");
 687         strbuf_addstr(sb,
 688                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 689         strbuf_addch(sb, ' ');
 690         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 691         strbuf_addch(sb, '\n');
 692 }
 693
 694 #define ORPHAN_CUTOFF 4
 695 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 696 {
 697         struct commit *c, *last = NULL;
 698         struct strbuf sb = STRBUF_INIT;
 699         int lost = 0;
 700         while ((c = get_revision(revs)) != NULL) {
 701                 if (lost < ORPHAN_CUTOFF)
 702                         describe_one_orphan(&sb, c);
 703                 last = c;
 704                 lost++;
 705         }
 706         if (ORPHAN_CUTOFF < lost) {
 707                 int more = lost - ORPHAN_CUTOFF;
 708                 if (more == 1)
 709                         describe_one_orphan(&sb, last);
 710                 else
 711                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 712         }
 713
 714         fprintf(stderr,
 715                 Q_(
 716                 /* The singular version */
 717                 "Warning: you are leaving %d commit behind, "
 718                 "not connected to\n"
 719                 "any of your branches:\n\n"
 720                 "%s\n",
 721                 /* The plural version */
 722                 "Warning: you are leaving %d commits behind, "
 723                 "not connected to\n"
 724                 "any of your branches:\n\n"
 725                 "%s\n",
 726                 /* Give ngettext() the count */
 727                 lost),
 728                 lost,
 729                 sb.buf);
 730         strbuf_release(&sb);
 731
 732         if (advice_detached_head)
 733                 fprintf(stderr,
 734                         _(
 735                         "If you want to keep them by creating a new branch, "
 736                         "this may be a good time\nto do so with:\n\n"
 737                         " git branch new_branch_name %s\n\n"),
 738                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 739 }
 740
 741 /*
 742  * We are about to leave commit that was at the tip of a detached
 743  * HEAD.  If it is not reachable from any ref, this is the last chance
 744  * for the user to do so without resorting to reflog.
 745  */
 746 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 747 {
 748         struct rev_info revs;
 749         struct object *object = &old->object;
 750         struct object_array refs;
 751
 752         init_revisions(&revs, NULL);
 753         setup_revisions(0, NULL, &revs, NULL);
 754
 755         object->flags &= ~UNINTERESTING;
 756         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 757
 758         for_each_ref(add_pending_uninteresting_ref, &revs);
 759         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 760
 761         refs = revs.pending;
 762         revs.leak_pending = 1;
 763
 764         if (prepare_revision_walk(&revs))
 765                 die(_("internal error in revision walk"));
 766         if (!(old->object.flags & UNINTERESTING))
 767                 suggest_reattach(old, &revs);
 768         else
 769                 describe_detached_head(_("Previous HEAD position was"), old);
 770
 771         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 772         free(refs.objects);
 773 }
 774
 775 static int switch_branches(const struct checkout_opts *opts,
 776                            struct branch_info *new)
 777 {
 778         int ret = 0;
 779         struct branch_info old;
 780         void *path_to_free;
 781         unsigned char rev[20];
 782         int flag, writeout_error = 0;
 783         memset(&old, 0, sizeof(old));
 784         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
 785         old.commit = lookup_commit_reference_gently(rev, 1);
 786         if (!(flag & REF_ISSYMREF))
 787                 old.path = NULL;
 788
 789         if (old.path && !prefixcmp(old.path, "refs/heads/"))
 790                 old.name = old.path + strlen("refs/heads/");
 791
 792         if (!new->name) {
 793                 new->name = "HEAD";
 794                 new->commit = old.commit;
 795                 if (!new->commit)
 796                         die(_("You are on a branch yet to be born"));
 797                 parse_commit(new->commit);
 798         }
 799
 800         ret = merge_working_tree(opts, &old, new, &writeout_error);
 801         if (ret) {
 802                 free(path_to_free);
 803                 return ret;
 804         }
 805
 806         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 807                 orphaned_commit_warning(old.commit, new->commit);
 808
 809         update_refs_for_switch(opts, &old, new);
 810
 811         ret = post_checkout_hook(old.commit, new->commit, 1);
 812         free(path_to_free);
 813         return ret || writeout_error;
 814 }
 815
 816 static int git_checkout_config(const char *var, const char *value, void *cb)
 817 {
 818         if (!strcmp(var, "diff.ignoresubmodules")) {
 819                 struct checkout_opts *opts = cb;
 820                 handle_ignore_submodules_arg(&opts->diff_options, value);
 821                 return 0;
 822         }
 823
 824         if (!prefixcmp(var, "submodule."))
 825                 return parse_submodule_config_option(var, value);
 826
 827         return git_xmerge_config(var, value, NULL);
 828 }
 829
 830 struct tracking_name_data {
 831         /* const */ char *src_ref;
 832         char *dst_ref;
 833         unsigned char *dst_sha1;
 834         int unique;
 835 };
 836
 837 static int check_tracking_name(struct remote *remote, void *cb_data)
 838 {
 839         struct tracking_name_data *cb = cb_data;
 840         struct refspec query;
 841         memset(&query, 0, sizeof(struct refspec));
 842         query.src = cb->src_ref;
 843         if (remote_find_tracking(remote, &query) ||
 844             get_sha1(query.dst, cb->dst_sha1)) {
 845                 free(query.dst);
 846                 return 0;
 847         }
 848         if (cb->dst_ref) {
 849                 free(query.dst);
 850                 cb->unique = 0;
 851                 return 0;
 852         }
 853         cb->dst_ref = query.dst;
 854         return 0;
 855 }
 856
 857 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 858 {
 859         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 860         char src_ref[PATH_MAX];
 861         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 862         cb_data.src_ref = src_ref;
 863         cb_data.dst_sha1 = sha1;
 864         for_each_remote(check_tracking_name, &cb_data);
 865         if (cb_data.unique)
 866                 return cb_data.dst_ref;
 867         free(cb_data.dst_ref);
 868         return NULL;
 869 }
 870
 871 static int parse_branchname_arg(int argc, const char **argv,
 872                                 int dwim_new_local_branch_ok,
 873                                 struct branch_info *new,
 874                                 struct tree **source_tree,
 875                                 unsigned char rev[20],
 876                                 const char **new_branch)
 877 {
 878         int argcount = 0;
 879         unsigned char branch_rev[20];
 880         const char *arg;
 881         int has_dash_dash;
 882
 883         /*
 884          * case 1: git checkout <ref> -- [<paths>]
 885          *
 886          *   <ref> must be a valid tree, everything after the '--' must be
 887          *   a path.
 888          *
 889          * case 2: git checkout -- [<paths>]
 890          *
 891          *   everything after the '--' must be paths.
 892          *
 893          * case 3: git checkout <something> [<paths>]
 894          *
 895          *   With no paths, if <something> is a commit, that is to
 896          *   switch to the branch or detach HEAD at it.  As a special case,
 897          *   if <something> is A...B (missing A or B means HEAD but you can
 898          *   omit at most one side), and if there is a unique merge base
 899          *   between A and B, A...B names that merge base.
 900          *
 901          *   With no paths, if <something> is _not_ a commit, no -t nor -b
 902          *   was given, and there is a tracking branch whose name is
 903          *   <something> in one and only one remote, then this is a short-hand
 904          *   to fork local <something> from that remote-tracking branch.
 905          *
 906          *   Otherwise <something> shall not be ambiguous.
 907          *   - If it's *only* a reference, treat it like case (1).
 908          *   - If it's only a path, treat it like case (2).
 909          *   - else: fail.
 910          *
 911          */
 912         if (!argc)
 913                 return 0;
 914
 915         if (!strcmp(argv[0], "--"))     /* case (2) */
 916                 return 1;
 917
 918         arg = argv[0];
 919         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 920
 921         if (!strcmp(arg, "-"))
 922                 arg = "@{-1}";
 923
 924         if (get_sha1_mb(arg, rev)) {
 925                 if (has_dash_dash)          /* case (1) */
 926                         die(_("invalid reference: %s"), arg);
 927                 if (dwim_new_local_branch_ok &&
 928                     !check_filename(NULL, arg) &&
 929                     argc == 1) {
 930                         const char *remote = unique_tracking_name(arg, rev);
 931                         if (!remote)
 932                                 return argcount;
 933                         *new_branch = arg;
 934                         arg = remote;
 935                         /* DWIMmed to create local branch */
 936                 } else {
 937                         return argcount;
 938                 }
 939         }
 940
 941         /* we can't end up being in (2) anymore, eat the argument */
 942         argcount++;
 943         argv++;
 944         argc--;
 945
 946         new->name = arg;
 947         setup_branch_path(new);
 948
 949         if (!check_refname_format(new->path, 0) &&
 950             !read_ref(new->path, branch_rev))
 951                 hashcpy(rev, branch_rev);
 952         else
 953                 new->path = NULL; /* not an existing branch */
 954
 955         new->commit = lookup_commit_reference_gently(rev, 1);
 956         if (!new->commit) {
 957                 /* not a commit */
 958                 *source_tree = parse_tree_indirect(rev);
 959         } else {
 960                 parse_commit(new->commit);
 961                 *source_tree = new->commit->tree;
 962         }
 963
 964         if (!*source_tree)                   /* case (1): want a tree */
 965                 die(_("reference is not a tree: %s"), arg);
 966         if (!has_dash_dash) {/* case (3 -> 1) */
 967                 /*
 968                  * Do not complain the most common case
 969                  *      git checkout branch
 970                  * even if there happen to be a file called 'branch';
 971                  * it would be extremely annoying.
 972                  */
 973                 if (argc)
 974                         verify_non_filename(NULL, arg);
 975         } else {
 976                 argcount++;
 977                 argv++;
 978                 argc--;
 979         }
 980
 981         return argcount;
 982 }
 983
 984 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
 985 {
 986         int status;
 987         struct strbuf branch_ref = STRBUF_INIT;
 988
 989         if (!opts->new_branch)
 990                 die(_("You are on a branch yet to be born"));
 991         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
 992         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
 993         strbuf_release(&branch_ref);
 994         if (!opts->quiet)
 995                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
 996                         opts->new_branch);
 997         return status;
 998 }
 999
1000 static int checkout_branch(struct checkout_opts *opts,
1001                            struct branch_info *new)
1002 {
1003         if (opts->pathspec.nr)
1004                 die(_("paths cannot be used with switching branches"));
1005
1006         if (opts->patch_mode)
1007                 die(_("'%s' cannot be used with switching branches"),
1008                     "--patch");
1009
1010         if (opts->writeout_stage)
1011                 die(_("'%s' cannot be used with switching branches"),
1012                     "--ours/--theirs");
1013
1014         if (opts->force && opts->merge)
1015                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1016
1017         if (opts->force_detach && opts->new_branch)
1018                 die(_("'%s' cannot be used with '%s'"),
1019                     "--detach", "-b/-B/--orphan");
1020
1021         if (opts->new_orphan_branch) {
1022                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1023                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1024         } else if (opts->force_detach) {
1025                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1026                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1027         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1028                 opts->track = git_branch_track;
1029
1030         if (new->name && !new->commit)
1031                 die(_("Cannot switch branch to a non-commit '%s'"),
1032                     new->name);
1033
1034         if (!new->commit && opts->new_branch) {
1035                 unsigned char rev[20];
1036                 int flag;
1037
1038                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
1039                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1040                         return switch_unborn_to_new_branch(opts);
1041         }
1042         return switch_branches(opts, new);
1043 }
1044
1045 int cmd_checkout(int argc, const char **argv, const char *prefix)
1046 {
1047         struct checkout_opts opts;
1048         struct branch_info new;
1049         char *conflict_style = NULL;
1050         int dwim_new_local_branch = 1;
1051         struct option options[] = {
1052                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1053                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1054                            N_("create and checkout a new branch")),
1055                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1056                            N_("create/reset and checkout a branch")),
1057                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1058                 OPT_BOOLEAN(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1059                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1060                         BRANCH_TRACK_EXPLICIT),
1061                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new branch"), N_("new unparented branch")),
1062                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1063                             2),
1064                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1065                             3),
1066                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1067                 OPT_BOOLEAN('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1068                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1069                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1070                            N_("conflict style (merge or diff3)")),
1071                 OPT_BOOLEAN('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1072                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1073                          N_("do not limit pathspecs to sparse entries only")),
1074                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
1075                   N_("second guess 'git checkout no-such-branch'"),
1076                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
1077                 OPT_END(),
1078         };
1079
1080         memset(&opts, 0, sizeof(opts));
1081         memset(&new, 0, sizeof(new));
1082         opts.overwrite_ignore = 1;
1083         opts.prefix = prefix;
1084
1085         gitmodules_config();
1086         git_config(git_checkout_config, &opts);
1087
1088         opts.track = BRANCH_TRACK_UNSPECIFIED;
1089
1090         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1091                              PARSE_OPT_KEEP_DASHDASH);
1092
1093         if (conflict_style) {
1094                 opts.merge = 1; /* implied */
1095                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1096         }
1097
1098         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1099                 die(_("-b, -B and --orphan are mutually exclusive"));
1100
1101         /*
1102          * From here on, new_branch will contain the branch to be checked out,
1103          * and new_branch_force and new_orphan_branch will tell us which one of
1104          * -b/-B/--orphan is being used.
1105          */
1106         if (opts.new_branch_force)
1107                 opts.new_branch = opts.new_branch_force;
1108
1109         if (opts.new_orphan_branch)
1110                 opts.new_branch = opts.new_orphan_branch;
1111
1112         /* --track without -b/-B/--orphan should DWIM */
1113         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1114                 const char *argv0 = argv[0];
1115                 if (!argc || !strcmp(argv0, "--"))
1116                         die (_("--track needs a branch name"));
1117                 if (!prefixcmp(argv0, "refs/"))
1118                         argv0 += 5;
1119                 if (!prefixcmp(argv0, "remotes/"))
1120                         argv0 += 8;
1121                 argv0 = strchr(argv0, '/');
1122                 if (!argv0 || !argv0[1])
1123                         die (_("Missing branch name; try -b"));
1124                 opts.new_branch = argv0 + 1;
1125         }
1126
1127         /*
1128          * Extract branch name from command line arguments, so
1129          * all that is left is pathspecs.
1130          *
1131          * Handle
1132          *
1133          *  1) git checkout <tree> -- [<paths>]
1134          *  2) git checkout -- [<paths>]
1135          *  3) git checkout <something> [<paths>]
1136          *
1137          * including "last branch" syntax and DWIM-ery for names of
1138          * remote branches, erroring out for invalid or ambiguous cases.
1139          */
1140         if (argc) {
1141                 unsigned char rev[20];
1142                 int dwim_ok =
1143                         !opts.patch_mode &&
1144                         dwim_new_local_branch &&
1145                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1146                         !opts.new_branch;
1147                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1148                                              &new, &opts.source_tree,
1149                                              rev, &opts.new_branch);
1150                 argv += n;
1151                 argc -= n;
1152         }
1153
1154         if (argc) {
1155                 /*
1156                  * In patch mode (opts.patch_mode != 0), we pass the
1157                  * pathspec to an external program, git-add--interactive.
1158                  * Do not accept any kind of magic that that program
1159                  * cannot handle. Magic mask is pretty safe to be
1160                  * lifted for new magic when opts.patch_mode == 0.
1161                  */
1162                 parse_pathspec(&opts.pathspec, 0,
1163                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1164                                prefix, argv);
1165
1166                 if (!opts.pathspec.nr)
1167                         die(_("invalid path specification"));
1168
1169                 /*
1170                  * Try to give more helpful suggestion.
1171                  * new_branch && argc > 1 will be caught later.
1172                  */
1173                 if (opts.new_branch && argc == 1)
1174                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1175                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1176                             opts.new_branch, argv[0]);
1177
1178                 if (opts.force_detach)
1179                         die(_("git checkout: --detach does not take a path argument '%s'"),
1180                             argv[0]);
1181
1182                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1183                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1184                               "checking out of the index."));
1185         }
1186
1187         if (opts.new_branch) {
1188                 struct strbuf buf = STRBUF_INIT;
1189
1190                 opts.branch_exists =
1191                         validate_new_branchname(opts.new_branch, &buf,
1192                                                 !!opts.new_branch_force,
1193                                                 !!opts.new_branch_force);
1194
1195                 strbuf_release(&buf);
1196         }
1197
1198         if (opts.patch_mode || opts.pathspec.nr)
1199                 return checkout_paths(&opts, new.name);
1200         else
1201                 return checkout_branch(&opts, &new);
1202 }