builtin/checkout.c

   1 #include "builtin.h"
   2 #include "lockfile.h"
   3 #include "parse-options.h"
   4 #include "refs.h"
   5 #include "commit.h"
   6 #include "tree.h"
   7 #include "tree-walk.h"
   8 #include "cache-tree.h"
   9 #include "unpack-trees.h"
  10 #include "dir.h"
  11 #include "run-command.h"
  12 #include "merge-recursive.h"
  13 #include "branch.h"
  14 #include "diff.h"
  15 #include "revision.h"
  16 #include "remote.h"
  17 #include "blob.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "resolve-undo.h"
  21 #include "submodule.h"
  22 #include "argv-array.h"
  23
  24 static const char * const checkout_usage[] = {
  25         N_("git checkout [<options>] <branch>"),
  26         N_("git checkout [<options>] [<branch>] -- <file>..."),
  27         NULL,
  28 };
  29
  30 struct checkout_opts {
  31         int patch_mode;
  32         int quiet;
  33         int merge;
  34         int force;
  35         int force_detach;
  36         int writeout_stage;
  37         int overwrite_ignore;
  38         int ignore_skipworktree;
  39
  40         const char *new_branch;
  41         const char *new_branch_force;
  42         const char *new_orphan_branch;
  43         int new_branch_log;
  44         enum branch_track track;
  45         struct diff_options diff_options;
  46
  47         int branch_exists;
  48         const char *prefix;
  49         struct pathspec pathspec;
  50         struct tree *source_tree;
  51 };
  52
  53 static int post_checkout_hook(struct commit *old, struct commit *new,
  54                               int changed)
  55 {
  56         return run_hook_le(NULL, "post-checkout",
  57                            sha1_to_hex(old ? old->object.sha1 : null_sha1),
  58                            sha1_to_hex(new ? new->object.sha1 : null_sha1),
  59                            changed ? "1" : "0", NULL);
  60         /* "new" can be NULL when checking out from the index before
  61            a commit exists. */
  62
  63 }
  64
  65 static int update_some(const unsigned char *sha1, struct strbuf *base,
  66                 const char *pathname, unsigned mode, int stage, void *context)
  67 {
  68         int len;
  69         struct cache_entry *ce;
  70         int pos;
  71
  72         if (S_ISDIR(mode))
  73                 return READ_TREE_RECURSIVE;
  74
  75         len = base->len + strlen(pathname);
  76         ce = xcalloc(1, cache_entry_size(len));
  77         hashcpy(ce->sha1, sha1);
  78         memcpy(ce->name, base->buf, base->len);
  79         memcpy(ce->name + base->len, pathname, len - base->len);
  80         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  81         ce->ce_namelen = len;
  82         ce->ce_mode = create_ce_mode(mode);
  83
  84         /*
  85          * If the entry is the same as the current index, we can leave the old
  86          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  87          * do the right thing.
  88          */
  89         pos = cache_name_pos(ce->name, ce->ce_namelen);
  90         if (pos >= 0) {
  91                 struct cache_entry *old = active_cache[pos];
  92                 if (ce->ce_mode == old->ce_mode &&
  93                     !hashcmp(ce->sha1, old->sha1)) {
  94                         old->ce_flags |= CE_UPDATE;
  95                         free(ce);
  96                         return 0;
  97                 }
  98         }
  99
 100         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 101         return 0;
 102 }
 103
 104 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 105 {
 106         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 107
 108         /* update the index with the given tree's info
 109          * for all args, expanding wildcards, and exit
 110          * with any non-zero return code.
 111          */
 112         return 0;
 113 }
 114
 115 static int skip_same_name(const struct cache_entry *ce, int pos)
 116 {
 117         while (++pos < active_nr &&
 118                !strcmp(active_cache[pos]->name, ce->name))
 119                 ; /* skip */
 120         return pos;
 121 }
 122
 123 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 124 {
 125         while (pos < active_nr &&
 126                !strcmp(active_cache[pos]->name, ce->name)) {
 127                 if (ce_stage(active_cache[pos]) == stage)
 128                         return 0;
 129                 pos++;
 130         }
 131         if (stage == 2)
 132                 return error(_("path '%s' does not have our version"), ce->name);
 133         else
 134                 return error(_("path '%s' does not have their version"), ce->name);
 135 }
 136
 137 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 138 {
 139         unsigned seen = 0;
 140         const char *name = ce->name;
 141
 142         while (pos < active_nr) {
 143                 ce = active_cache[pos];
 144                 if (strcmp(name, ce->name))
 145                         break;
 146                 seen |= (1 << ce_stage(ce));
 147                 pos++;
 148         }
 149         if ((stages & seen) != stages)
 150                 return error(_("path '%s' does not have all necessary versions"),
 151                              name);
 152         return 0;
 153 }
 154
 155 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 156                           struct checkout *state)
 157 {
 158         while (pos < active_nr &&
 159                !strcmp(active_cache[pos]->name, ce->name)) {
 160                 if (ce_stage(active_cache[pos]) == stage)
 161                         return checkout_entry(active_cache[pos], state, NULL);
 162                 pos++;
 163         }
 164         if (stage == 2)
 165                 return error(_("path '%s' does not have our version"), ce->name);
 166         else
 167                 return error(_("path '%s' does not have their version"), ce->name);
 168 }
 169
 170 static int checkout_merged(int pos, struct checkout *state)
 171 {
 172         struct cache_entry *ce = active_cache[pos];
 173         const char *path = ce->name;
 174         mmfile_t ancestor, ours, theirs;
 175         int status;
 176         unsigned char sha1[20];
 177         mmbuffer_t result_buf;
 178         unsigned char threeway[3][20];
 179         unsigned mode = 0;
 180
 181         memset(threeway, 0, sizeof(threeway));
 182         while (pos < active_nr) {
 183                 int stage;
 184                 stage = ce_stage(ce);
 185                 if (!stage || strcmp(path, ce->name))
 186                         break;
 187                 hashcpy(threeway[stage - 1], ce->sha1);
 188                 if (stage == 2)
 189                         mode = create_ce_mode(ce->ce_mode);
 190                 pos++;
 191                 ce = active_cache[pos];
 192         }
 193         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
 194                 return error(_("path '%s' does not have necessary versions"), path);
 195
 196         read_mmblob(&ancestor, threeway[0]);
 197         read_mmblob(&ours, threeway[1]);
 198         read_mmblob(&theirs, threeway[2]);
 199
 200         /*
 201          * NEEDSWORK: re-create conflicts from merges with
 202          * merge.renormalize set, too
 203          */
 204         status = ll_merge(&result_buf, path, &ancestor, "base",
 205                           &ours, "ours", &theirs, "theirs", NULL);
 206         free(ancestor.ptr);
 207         free(ours.ptr);
 208         free(theirs.ptr);
 209         if (status < 0 || !result_buf.ptr) {
 210                 free(result_buf.ptr);
 211                 return error(_("path '%s': cannot merge"), path);
 212         }
 213
 214         /*
 215          * NEEDSWORK:
 216          * There is absolutely no reason to write this as a blob object
 217          * and create a phony cache entry just to leak.  This hack is
 218          * primarily to get to the write_entry() machinery that massages
 219          * the contents to work-tree format and writes out which only
 220          * allows it for a cache entry.  The code in write_entry() needs
 221          * to be refactored to allow us to feed a <buffer, size, mode>
 222          * instead of a cache entry.  Such a refactoring would help
 223          * merge_recursive as well (it also writes the merge result to the
 224          * object database even when it may contain conflicts).
 225          */
 226         if (write_sha1_file(result_buf.ptr, result_buf.size,
 227                             blob_type, sha1))
 228                 die(_("Unable to add merge result for '%s'"), path);
 229         ce = make_cache_entry(mode, sha1, path, 2, 0);
 230         if (!ce)
 231                 die(_("make_cache_entry failed for path '%s'"), path);
 232         status = checkout_entry(ce, state, NULL);
 233         return status;
 234 }
 235
 236 static int checkout_paths(const struct checkout_opts *opts,
 237                           const char *revision)
 238 {
 239         int pos;
 240         struct checkout state;
 241         static char *ps_matched;
 242         unsigned char rev[20];
 243         int flag;
 244         struct commit *head;
 245         int errs = 0;
 246         struct lock_file *lock_file;
 247
 248         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 249                 die(_("'%s' cannot be used with updating paths"), "--track");
 250
 251         if (opts->new_branch_log)
 252                 die(_("'%s' cannot be used with updating paths"), "-l");
 253
 254         if (opts->force && opts->patch_mode)
 255                 die(_("'%s' cannot be used with updating paths"), "-f");
 256
 257         if (opts->force_detach)
 258                 die(_("'%s' cannot be used with updating paths"), "--detach");
 259
 260         if (opts->merge && opts->patch_mode)
 261                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 262
 263         if (opts->force && opts->merge)
 264                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 265
 266         if (opts->new_branch)
 267                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 268                     opts->new_branch);
 269
 270         if (opts->patch_mode)
 271                 return run_add_interactive(revision, "--patch=checkout",
 272                                            &opts->pathspec);
 273
 274         lock_file = xcalloc(1, sizeof(struct lock_file));
 275
 276         hold_locked_index(lock_file, 1);
 277         if (read_cache_preload(&opts->pathspec) < 0)
 278                 return error(_("corrupt index file"));
 279
 280         if (opts->source_tree)
 281                 read_tree_some(opts->source_tree, &opts->pathspec);
 282
 283         ps_matched = xcalloc(1, opts->pathspec.nr);
 284
 285         /*
 286          * Make sure all pathspecs participated in locating the paths
 287          * to be checked out.
 288          */
 289         for (pos = 0; pos < active_nr; pos++) {
 290                 struct cache_entry *ce = active_cache[pos];
 291                 ce->ce_flags &= ~CE_MATCHED;
 292                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 293                         continue;
 294                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 295                         /*
 296                          * "git checkout tree-ish -- path", but this entry
 297                          * is in the original index; it will not be checked
 298                          * out to the working tree and it does not matter
 299                          * if pathspec matched this entry.  We will not do
 300                          * anything to this entry at all.
 301                          */
 302                         continue;
 303                 /*
 304                  * Either this entry came from the tree-ish we are
 305                  * checking the paths out of, or we are checking out
 306                  * of the index.
 307                  *
 308                  * If it comes from the tree-ish, we already know it
 309                  * matches the pathspec and could just stamp
 310                  * CE_MATCHED to it from update_some(). But we still
 311                  * need ps_matched and read_tree_recursive (and
 312                  * eventually tree_entry_interesting) cannot fill
 313                  * ps_matched yet. Once it can, we can avoid calling
 314                  * match_pathspec() for _all_ entries when
 315                  * opts->source_tree != NULL.
 316                  */
 317                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
 318                         ce->ce_flags |= CE_MATCHED;
 319         }
 320
 321         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 322                 free(ps_matched);
 323                 return 1;
 324         }
 325         free(ps_matched);
 326
 327         /* "checkout -m path" to recreate conflicted state */
 328         if (opts->merge)
 329                 unmerge_marked_index(&the_index);
 330
 331         /* Any unmerged paths? */
 332         for (pos = 0; pos < active_nr; pos++) {
 333                 const struct cache_entry *ce = active_cache[pos];
 334                 if (ce->ce_flags & CE_MATCHED) {
 335                         if (!ce_stage(ce))
 336                                 continue;
 337                         if (opts->force) {
 338                                 warning(_("path '%s' is unmerged"), ce->name);
 339                         } else if (opts->writeout_stage) {
 340                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 341                         } else if (opts->merge) {
 342                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 343                         } else {
 344                                 errs = 1;
 345                                 error(_("path '%s' is unmerged"), ce->name);
 346                         }
 347                         pos = skip_same_name(ce, pos) - 1;
 348                 }
 349         }
 350         if (errs)
 351                 return 1;
 352
 353         /* Now we are committed to check them out */
 354         memset(&state, 0, sizeof(state));
 355         state.force = 1;
 356         state.refresh_cache = 1;
 357         state.istate = &the_index;
 358         for (pos = 0; pos < active_nr; pos++) {
 359                 struct cache_entry *ce = active_cache[pos];
 360                 if (ce->ce_flags & CE_MATCHED) {
 361                         if (!ce_stage(ce)) {
 362                                 errs |= checkout_entry(ce, &state, NULL);
 363                                 continue;
 364                         }
 365                         if (opts->writeout_stage)
 366                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 367                         else if (opts->merge)
 368                                 errs |= checkout_merged(pos, &state);
 369                         pos = skip_same_name(ce, pos) - 1;
 370                 }
 371         }
 372
 373         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 374                 die(_("unable to write new index file"));
 375
 376         read_ref_full("HEAD", 0, rev, &flag);
 377         head = lookup_commit_reference_gently(rev, 1);
 378
 379         errs |= post_checkout_hook(head, head, 0);
 380         return errs;
 381 }
 382
 383 static void show_local_changes(struct object *head,
 384                                const struct diff_options *opts)
 385 {
 386         struct rev_info rev;
 387         /* I think we want full paths, even if we're in a subdirectory. */
 388         init_revisions(&rev, NULL);
 389         rev.diffopt.flags = opts->flags;
 390         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 391         diff_setup_done(&rev.diffopt);
 392         add_pending_object(&rev, head, NULL);
 393         run_diff_index(&rev, 0);
 394 }
 395
 396 static void describe_detached_head(const char *msg, struct commit *commit)
 397 {
 398         struct strbuf sb = STRBUF_INIT;
 399         if (!parse_commit(commit))
 400                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 401         fprintf(stderr, "%s %s... %s\n", msg,
 402                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 403         strbuf_release(&sb);
 404 }
 405
 406 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 407                       int worktree, int *writeout_error)
 408 {
 409         struct unpack_trees_options opts;
 410         struct tree_desc tree_desc;
 411
 412         memset(&opts, 0, sizeof(opts));
 413         opts.head_idx = -1;
 414         opts.update = worktree;
 415         opts.skip_unmerged = !worktree;
 416         opts.reset = 1;
 417         opts.merge = 1;
 418         opts.fn = oneway_merge;
 419         opts.verbose_update = !o->quiet && isatty(2);
 420         opts.src_index = &the_index;
 421         opts.dst_index = &the_index;
 422         parse_tree(tree);
 423         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 424         switch (unpack_trees(1, &tree_desc, &opts)) {
 425         case -2:
 426                 *writeout_error = 1;
 427                 /*
 428                  * We return 0 nevertheless, as the index is all right
 429                  * and more importantly we have made best efforts to
 430                  * update paths in the work tree, and we cannot revert
 431                  * them.
 432                  */
 433         case 0:
 434                 return 0;
 435         default:
 436                 return 128;
 437         }
 438 }
 439
 440 struct branch_info {
 441         const char *name; /* The short name used */
 442         const char *path; /* The full name of a real branch */
 443         struct commit *commit; /* The named commit */
 444 };
 445
 446 static void setup_branch_path(struct branch_info *branch)
 447 {
 448         struct strbuf buf = STRBUF_INIT;
 449
 450         strbuf_branchname(&buf, branch->name);
 451         if (strcmp(buf.buf, branch->name))
 452                 branch->name = xstrdup(buf.buf);
 453         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 454         branch->path = strbuf_detach(&buf, NULL);
 455 }
 456
 457 static int merge_working_tree(const struct checkout_opts *opts,
 458                               struct branch_info *old,
 459                               struct branch_info *new,
 460                               int *writeout_error)
 461 {
 462         int ret;
 463         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 464
 465         hold_locked_index(lock_file, 1);
 466         if (read_cache_preload(NULL) < 0)
 467                 return error(_("corrupt index file"));
 468
 469         resolve_undo_clear();
 470         if (opts->force) {
 471                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 472                 if (ret)
 473                         return ret;
 474         } else {
 475                 struct tree_desc trees[2];
 476                 struct tree *tree;
 477                 struct unpack_trees_options topts;
 478
 479                 memset(&topts, 0, sizeof(topts));
 480                 topts.head_idx = -1;
 481                 topts.src_index = &the_index;
 482                 topts.dst_index = &the_index;
 483
 484                 setup_unpack_trees_porcelain(&topts, "checkout");
 485
 486                 refresh_cache(REFRESH_QUIET);
 487
 488                 if (unmerged_cache()) {
 489                         error(_("you need to resolve your current index first"));
 490                         return 1;
 491                 }
 492
 493                 /* 2-way merge to the new branch */
 494                 topts.initial_checkout = is_cache_unborn();
 495                 topts.update = 1;
 496                 topts.merge = 1;
 497                 topts.gently = opts->merge && old->commit;
 498                 topts.verbose_update = !opts->quiet && isatty(2);
 499                 topts.fn = twoway_merge;
 500                 if (opts->overwrite_ignore) {
 501                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 502                         topts.dir->flags |= DIR_SHOW_IGNORED;
 503                         setup_standard_excludes(topts.dir);
 504                 }
 505                 tree = parse_tree_indirect(old->commit ?
 506                                            old->commit->object.sha1 :
 507                                            EMPTY_TREE_SHA1_BIN);
 508                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 509                 tree = parse_tree_indirect(new->commit->object.sha1);
 510                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 511
 512                 ret = unpack_trees(2, trees, &topts);
 513                 if (ret == -1) {
 514                         /*
 515                          * Unpack couldn't do a trivial merge; either
 516                          * give up or do a real merge, depending on
 517                          * whether the merge flag was used.
 518                          */
 519                         struct tree *result;
 520                         struct tree *work;
 521                         struct merge_options o;
 522                         if (!opts->merge)
 523                                 return 1;
 524
 525                         /*
 526                          * Without old->commit, the below is the same as
 527                          * the two-tree unpack we already tried and failed.
 528                          */
 529                         if (!old->commit)
 530                                 return 1;
 531
 532                         /* Do more real merge */
 533
 534                         /*
 535                          * We update the index fully, then write the
 536                          * tree from the index, then merge the new
 537                          * branch with the current tree, with the old
 538                          * branch as the base. Then we reset the index
 539                          * (but not the working tree) to the new
 540                          * branch, leaving the working tree as the
 541                          * merged version, but skipping unmerged
 542                          * entries in the index.
 543                          */
 544
 545                         add_files_to_cache(NULL, NULL, 0);
 546                         /*
 547                          * NEEDSWORK: carrying over local changes
 548                          * when branches have different end-of-line
 549                          * normalization (or clean+smudge rules) is
 550                          * a pain; plumb in an option to set
 551                          * o.renormalize?
 552                          */
 553                         init_merge_options(&o);
 554                         o.verbosity = 0;
 555                         work = write_tree_from_memory(&o);
 556
 557                         ret = reset_tree(new->commit->tree, opts, 1,
 558                                          writeout_error);
 559                         if (ret)
 560                                 return ret;
 561                         o.ancestor = old->name;
 562                         o.branch1 = new->name;
 563                         o.branch2 = "local";
 564                         merge_trees(&o, new->commit->tree, work,
 565                                 old->commit->tree, &result);
 566                         ret = reset_tree(new->commit->tree, opts, 0,
 567                                          writeout_error);
 568                         if (ret)
 569                                 return ret;
 570                 }
 571         }
 572
 573         if (!active_cache_tree)
 574                 active_cache_tree = cache_tree();
 575
 576         if (!cache_tree_fully_valid(active_cache_tree))
 577                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 578
 579         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 580                 die(_("unable to write new index file"));
 581
 582         if (!opts->force && !opts->quiet)
 583                 show_local_changes(&new->commit->object, &opts->diff_options);
 584
 585         return 0;
 586 }
 587
 588 static void report_tracking(struct branch_info *new)
 589 {
 590         struct strbuf sb = STRBUF_INIT;
 591         struct branch *branch = branch_get(new->name);
 592
 593         if (!format_tracking_info(branch, &sb))
 594                 return;
 595         fputs(sb.buf, stdout);
 596         strbuf_release(&sb);
 597 }
 598
 599 static void update_refs_for_switch(const struct checkout_opts *opts,
 600                                    struct branch_info *old,
 601                                    struct branch_info *new)
 602 {
 603         struct strbuf msg = STRBUF_INIT;
 604         const char *old_desc, *reflog_msg;
 605         if (opts->new_branch) {
 606                 if (opts->new_orphan_branch) {
 607                         if (opts->new_branch_log && !log_all_ref_updates) {
 608                                 int temp;
 609                                 char log_file[PATH_MAX];
 610                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 611
 612                                 temp = log_all_ref_updates;
 613                                 log_all_ref_updates = 1;
 614                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 615                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 616                                             opts->new_orphan_branch);
 617                                         log_all_ref_updates = temp;
 618                                         return;
 619                                 }
 620                                 log_all_ref_updates = temp;
 621                         }
 622                 }
 623                 else
 624                         create_branch(old->name, opts->new_branch, new->name,
 625                                       opts->new_branch_force ? 1 : 0,
 626                                       opts->new_branch_log,
 627                                       opts->new_branch_force ? 1 : 0,
 628                                       opts->quiet,
 629                                       opts->track);
 630                 new->name = opts->new_branch;
 631                 setup_branch_path(new);
 632         }
 633
 634         old_desc = old->name;
 635         if (!old_desc && old->commit)
 636                 old_desc = sha1_to_hex(old->commit->object.sha1);
 637
 638         reflog_msg = getenv("GIT_REFLOG_ACTION");
 639         if (!reflog_msg)
 640                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 641                         old_desc ? old_desc : "(invalid)", new->name);
 642         else
 643                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 644
 645         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 646                 /* Nothing to do. */
 647         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 648                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 649                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 650                 if (!opts->quiet) {
 651                         if (old->path && advice_detached_head)
 652                                 detach_advice(new->name);
 653                         describe_detached_head(_("HEAD is now at"), new->commit);
 654                 }
 655         } else if (new->path) { /* Switch branches. */
 656                 create_symref("HEAD", new->path, msg.buf);
 657                 if (!opts->quiet) {
 658                         if (old->path && !strcmp(new->path, old->path)) {
 659                                 if (opts->new_branch_force)
 660                                         fprintf(stderr, _("Reset branch '%s'\n"),
 661                                                 new->name);
 662                                 else
 663                                         fprintf(stderr, _("Already on '%s'\n"),
 664                                                 new->name);
 665                         } else if (opts->new_branch) {
 666                                 if (opts->branch_exists)
 667                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 668                                 else
 669                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 670                         } else {
 671                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 672                                         new->name);
 673                         }
 674                 }
 675                 if (old->path && old->name) {
 676                         if (!ref_exists(old->path) && reflog_exists(old->path))
 677                                 delete_reflog(old->path);
 678                 }
 679         }
 680         remove_branch_state();
 681         strbuf_release(&msg);
 682         if (!opts->quiet &&
 683             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 684                 report_tracking(new);
 685 }
 686
 687 static int add_pending_uninteresting_ref(const char *refname,
 688                                          const unsigned char *sha1,
 689                                          int flags, void *cb_data)
 690 {
 691         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 692         return 0;
 693 }
 694
 695 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 696 {
 697         strbuf_addstr(sb, "  ");
 698         strbuf_addstr(sb,
 699                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 700         strbuf_addch(sb, ' ');
 701         if (!parse_commit(commit))
 702                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 703         strbuf_addch(sb, '\n');
 704 }
 705
 706 #define ORPHAN_CUTOFF 4
 707 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 708 {
 709         struct commit *c, *last = NULL;
 710         struct strbuf sb = STRBUF_INIT;
 711         int lost = 0;
 712         while ((c = get_revision(revs)) != NULL) {
 713                 if (lost < ORPHAN_CUTOFF)
 714                         describe_one_orphan(&sb, c);
 715                 last = c;
 716                 lost++;
 717         }
 718         if (ORPHAN_CUTOFF < lost) {
 719                 int more = lost - ORPHAN_CUTOFF;
 720                 if (more == 1)
 721                         describe_one_orphan(&sb, last);
 722                 else
 723                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 724         }
 725
 726         fprintf(stderr,
 727                 Q_(
 728                 /* The singular version */
 729                 "Warning: you are leaving %d commit behind, "
 730                 "not connected to\n"
 731                 "any of your branches:\n\n"
 732                 "%s\n",
 733                 /* The plural version */
 734                 "Warning: you are leaving %d commits behind, "
 735                 "not connected to\n"
 736                 "any of your branches:\n\n"
 737                 "%s\n",
 738                 /* Give ngettext() the count */
 739                 lost),
 740                 lost,
 741                 sb.buf);
 742         strbuf_release(&sb);
 743
 744         if (advice_detached_head)
 745                 fprintf(stderr,
 746                         _(
 747                         "If you want to keep them by creating a new branch, "
 748                         "this may be a good time\nto do so with:\n\n"
 749                         " git branch <new-branch-name> %s\n\n"),
 750                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 751 }
 752
 753 /*
 754  * We are about to leave commit that was at the tip of a detached
 755  * HEAD.  If it is not reachable from any ref, this is the last chance
 756  * for the user to do so without resorting to reflog.
 757  */
 758 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 759 {
 760         struct rev_info revs;
 761         struct object *object = &old->object;
 762         struct object_array refs;
 763
 764         init_revisions(&revs, NULL);
 765         setup_revisions(0, NULL, &revs, NULL);
 766
 767         object->flags &= ~UNINTERESTING;
 768         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 769
 770         for_each_ref(add_pending_uninteresting_ref, &revs);
 771         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 772
 773         refs = revs.pending;
 774         revs.leak_pending = 1;
 775
 776         if (prepare_revision_walk(&revs))
 777                 die(_("internal error in revision walk"));
 778         if (!(old->object.flags & UNINTERESTING))
 779                 suggest_reattach(old, &revs);
 780         else
 781                 describe_detached_head(_("Previous HEAD position was"), old);
 782
 783         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 784         free(refs.objects);
 785 }
 786
 787 static int switch_branches(const struct checkout_opts *opts,
 788                            struct branch_info *new)
 789 {
 790         int ret = 0;
 791         struct branch_info old;
 792         void *path_to_free;
 793         unsigned char rev[20];
 794         int flag, writeout_error = 0;
 795         memset(&old, 0, sizeof(old));
 796         old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 797         old.commit = lookup_commit_reference_gently(rev, 1);
 798         if (!(flag & REF_ISSYMREF))
 799                 old.path = NULL;
 800
 801         if (old.path)
 802                 skip_prefix(old.path, "refs/heads/", &old.name);
 803
 804         if (!new->name) {
 805                 new->name = "HEAD";
 806                 new->commit = old.commit;
 807                 if (!new->commit)
 808                         die(_("You are on a branch yet to be born"));
 809                 parse_commit_or_die(new->commit);
 810         }
 811
 812         ret = merge_working_tree(opts, &old, new, &writeout_error);
 813         if (ret) {
 814                 free(path_to_free);
 815                 return ret;
 816         }
 817
 818         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 819                 orphaned_commit_warning(old.commit, new->commit);
 820
 821         update_refs_for_switch(opts, &old, new);
 822
 823         ret = post_checkout_hook(old.commit, new->commit, 1);
 824         free(path_to_free);
 825         return ret || writeout_error;
 826 }
 827
 828 static int git_checkout_config(const char *var, const char *value, void *cb)
 829 {
 830         if (!strcmp(var, "diff.ignoresubmodules")) {
 831                 struct checkout_opts *opts = cb;
 832                 handle_ignore_submodules_arg(&opts->diff_options, value);
 833                 return 0;
 834         }
 835
 836         if (starts_with(var, "submodule."))
 837                 return parse_submodule_config_option(var, value);
 838
 839         return git_xmerge_config(var, value, NULL);
 840 }
 841
 842 struct tracking_name_data {
 843         /* const */ char *src_ref;
 844         char *dst_ref;
 845         unsigned char *dst_sha1;
 846         int unique;
 847 };
 848
 849 static int check_tracking_name(struct remote *remote, void *cb_data)
 850 {
 851         struct tracking_name_data *cb = cb_data;
 852         struct refspec query;
 853         memset(&query, 0, sizeof(struct refspec));
 854         query.src = cb->src_ref;
 855         if (remote_find_tracking(remote, &query) ||
 856             get_sha1(query.dst, cb->dst_sha1)) {
 857                 free(query.dst);
 858                 return 0;
 859         }
 860         if (cb->dst_ref) {
 861                 free(query.dst);
 862                 cb->unique = 0;
 863                 return 0;
 864         }
 865         cb->dst_ref = query.dst;
 866         return 0;
 867 }
 868
 869 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 870 {
 871         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 872         char src_ref[PATH_MAX];
 873         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 874         cb_data.src_ref = src_ref;
 875         cb_data.dst_sha1 = sha1;
 876         for_each_remote(check_tracking_name, &cb_data);
 877         if (cb_data.unique)
 878                 return cb_data.dst_ref;
 879         free(cb_data.dst_ref);
 880         return NULL;
 881 }
 882
 883 static int parse_branchname_arg(int argc, const char **argv,
 884                                 int dwim_new_local_branch_ok,
 885                                 struct branch_info *new,
 886                                 struct tree **source_tree,
 887                                 unsigned char rev[20],
 888                                 const char **new_branch)
 889 {
 890         int argcount = 0;
 891         unsigned char branch_rev[20];
 892         const char *arg;
 893         int dash_dash_pos;
 894         int has_dash_dash = 0;
 895         int i;
 896
 897         /*
 898          * case 1: git checkout <ref> -- [<paths>]
 899          *
 900          *   <ref> must be a valid tree, everything after the '--' must be
 901          *   a path.
 902          *
 903          * case 2: git checkout -- [<paths>]
 904          *
 905          *   everything after the '--' must be paths.
 906          *
 907          * case 3: git checkout <something> [--]
 908          *
 909          *   (a) If <something> is a commit, that is to
 910          *       switch to the branch or detach HEAD at it.  As a special case,
 911          *       if <something> is A...B (missing A or B means HEAD but you can
 912          *       omit at most one side), and if there is a unique merge base
 913          *       between A and B, A...B names that merge base.
 914          *
 915          *   (b) If <something> is _not_ a commit, either "--" is present
 916          *       or <something> is not a path, no -t or -b was given, and
 917          *       and there is a tracking branch whose name is <something>
 918          *       in one and only one remote, then this is a short-hand to
 919          *       fork local <something> from that remote-tracking branch.
 920          *
 921          *   (c) Otherwise, if "--" is present, treat it like case (1).
 922          *
 923          *   (d) Otherwise :
 924          *       - if it's a reference, treat it like case (1)
 925          *       - else if it's a path, treat it like case (2)
 926          *       - else: fail.
 927          *
 928          * case 4: git checkout <something> <paths>
 929          *
 930          *   The first argument must not be ambiguous.
 931          *   - If it's *only* a reference, treat it like case (1).
 932          *   - If it's only a path, treat it like case (2).
 933          *   - else: fail.
 934          *
 935          */
 936         if (!argc)
 937                 return 0;
 938
 939         arg = argv[0];
 940         dash_dash_pos = -1;
 941         for (i = 0; i < argc; i++) {
 942                 if (!strcmp(argv[i], "--")) {
 943                         dash_dash_pos = i;
 944                         break;
 945                 }
 946         }
 947         if (dash_dash_pos == 0)
 948                 return 1; /* case (2) */
 949         else if (dash_dash_pos == 1)
 950                 has_dash_dash = 1; /* case (3) or (1) */
 951         else if (dash_dash_pos >= 2)
 952                 die(_("only one reference expected, %d given."), dash_dash_pos);
 953
 954         if (!strcmp(arg, "-"))
 955                 arg = "@{-1}";
 956
 957         if (get_sha1_mb(arg, rev)) {
 958                 /*
 959                  * Either case (3) or (4), with <something> not being
 960                  * a commit, or an attempt to use case (1) with an
 961                  * invalid ref.
 962                  *
 963                  * It's likely an error, but we need to find out if
 964                  * we should auto-create the branch, case (3).(b).
 965                  */
 966                 int recover_with_dwim = dwim_new_local_branch_ok;
 967
 968                 if (check_filename(NULL, arg) && !has_dash_dash)
 969                         recover_with_dwim = 0;
 970                 /*
 971                  * Accept "git checkout foo" and "git checkout foo --"
 972                  * as candidates for dwim.
 973                  */
 974                 if (!(argc == 1 && !has_dash_dash) &&
 975                     !(argc == 2 && has_dash_dash))
 976                         recover_with_dwim = 0;
 977
 978                 if (recover_with_dwim) {
 979                         const char *remote = unique_tracking_name(arg, rev);
 980                         if (remote) {
 981                                 *new_branch = arg;
 982                                 arg = remote;
 983                                 /* DWIMmed to create local branch, case (3).(b) */
 984                         } else {
 985                                 recover_with_dwim = 0;
 986                         }
 987                 }
 988
 989                 if (!recover_with_dwim) {
 990                         if (has_dash_dash)
 991                                 die(_("invalid reference: %s"), arg);
 992                         return argcount;
 993                 }
 994         }
 995
 996         /* we can't end up being in (2) anymore, eat the argument */
 997         argcount++;
 998         argv++;
 999         argc--;
1000
1001         new->name = arg;
1002         setup_branch_path(new);
1003
1004         if (!check_refname_format(new->path, 0) &&
1005             !read_ref(new->path, branch_rev))
1006                 hashcpy(rev, branch_rev);
1007         else
1008                 new->path = NULL; /* not an existing branch */
1009
1010         new->commit = lookup_commit_reference_gently(rev, 1);
1011         if (!new->commit) {
1012                 /* not a commit */
1013                 *source_tree = parse_tree_indirect(rev);
1014         } else {
1015                 parse_commit_or_die(new->commit);
1016                 *source_tree = new->commit->tree;
1017         }
1018
1019         if (!*source_tree)                   /* case (1): want a tree */
1020                 die(_("reference is not a tree: %s"), arg);
1021         if (!has_dash_dash) {/* case (3).(d) -> (1) */
1022                 /*
1023                  * Do not complain the most common case
1024                  *      git checkout branch
1025                  * even if there happen to be a file called 'branch';
1026                  * it would be extremely annoying.
1027                  */
1028                 if (argc)
1029                         verify_non_filename(NULL, arg);
1030         } else {
1031                 argcount++;
1032                 argv++;
1033                 argc--;
1034         }
1035
1036         return argcount;
1037 }
1038
1039 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1040 {
1041         int status;
1042         struct strbuf branch_ref = STRBUF_INIT;
1043
1044         if (!opts->new_branch)
1045                 die(_("You are on a branch yet to be born"));
1046         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1047         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1048         strbuf_release(&branch_ref);
1049         if (!opts->quiet)
1050                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1051                         opts->new_branch);
1052         return status;
1053 }
1054
1055 static int checkout_branch(struct checkout_opts *opts,
1056                            struct branch_info *new)
1057 {
1058         if (opts->pathspec.nr)
1059                 die(_("paths cannot be used with switching branches"));
1060
1061         if (opts->patch_mode)
1062                 die(_("'%s' cannot be used with switching branches"),
1063                     "--patch");
1064
1065         if (opts->writeout_stage)
1066                 die(_("'%s' cannot be used with switching branches"),
1067                     "--ours/--theirs");
1068
1069         if (opts->force && opts->merge)
1070                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1071
1072         if (opts->force_detach && opts->new_branch)
1073                 die(_("'%s' cannot be used with '%s'"),
1074                     "--detach", "-b/-B/--orphan");
1075
1076         if (opts->new_orphan_branch) {
1077                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1078                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1079         } else if (opts->force_detach) {
1080                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1081                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1082         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1083                 opts->track = git_branch_track;
1084
1085         if (new->name && !new->commit)
1086                 die(_("Cannot switch branch to a non-commit '%s'"),
1087                     new->name);
1088
1089         if (!new->commit && opts->new_branch) {
1090                 unsigned char rev[20];
1091                 int flag;
1092
1093                 if (!read_ref_full("HEAD", 0, rev, &flag) &&
1094                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1095                         return switch_unborn_to_new_branch(opts);
1096         }
1097         return switch_branches(opts, new);
1098 }
1099
1100 int cmd_checkout(int argc, const char **argv, const char *prefix)
1101 {
1102         struct checkout_opts opts;
1103         struct branch_info new;
1104         char *conflict_style = NULL;
1105         int dwim_new_local_branch = 1;
1106         struct option options[] = {
1107                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1108                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1109                            N_("create and checkout a new branch")),
1110                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1111                            N_("create/reset and checkout a branch")),
1112                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1113                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1114                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1115                         BRANCH_TRACK_EXPLICIT),
1116                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1117                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1118                             2),
1119                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1120                             3),
1121                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1122                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1123                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1124                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1125                            N_("conflict style (merge or diff3)")),
1126                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1127                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1128                          N_("do not limit pathspecs to sparse entries only")),
1129                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1130                                 N_("second guess 'git checkout <no-such-branch>'")),
1131                 OPT_END(),
1132         };
1133
1134         memset(&opts, 0, sizeof(opts));
1135         memset(&new, 0, sizeof(new));
1136         opts.overwrite_ignore = 1;
1137         opts.prefix = prefix;
1138
1139         gitmodules_config();
1140         git_config(git_checkout_config, &opts);
1141
1142         opts.track = BRANCH_TRACK_UNSPECIFIED;
1143
1144         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1145                              PARSE_OPT_KEEP_DASHDASH);
1146
1147         if (conflict_style) {
1148                 opts.merge = 1; /* implied */
1149                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1150         }
1151
1152         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1153                 die(_("-b, -B and --orphan are mutually exclusive"));
1154
1155         /*
1156          * From here on, new_branch will contain the branch to be checked out,
1157          * and new_branch_force and new_orphan_branch will tell us which one of
1158          * -b/-B/--orphan is being used.
1159          */
1160         if (opts.new_branch_force)
1161                 opts.new_branch = opts.new_branch_force;
1162
1163         if (opts.new_orphan_branch)
1164                 opts.new_branch = opts.new_orphan_branch;
1165
1166         /* --track without -b/-B/--orphan should DWIM */
1167         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1168                 const char *argv0 = argv[0];
1169                 if (!argc || !strcmp(argv0, "--"))
1170                         die (_("--track needs a branch name"));
1171                 skip_prefix(argv0, "refs/", &argv0);
1172                 skip_prefix(argv0, "remotes/", &argv0);
1173                 argv0 = strchr(argv0, '/');
1174                 if (!argv0 || !argv0[1])
1175                         die (_("Missing branch name; try -b"));
1176                 opts.new_branch = argv0 + 1;
1177         }
1178
1179         /*
1180          * Extract branch name from command line arguments, so
1181          * all that is left is pathspecs.
1182          *
1183          * Handle
1184          *
1185          *  1) git checkout <tree> -- [<paths>]
1186          *  2) git checkout -- [<paths>]
1187          *  3) git checkout <something> [<paths>]
1188          *
1189          * including "last branch" syntax and DWIM-ery for names of
1190          * remote branches, erroring out for invalid or ambiguous cases.
1191          */
1192         if (argc) {
1193                 unsigned char rev[20];
1194                 int dwim_ok =
1195                         !opts.patch_mode &&
1196                         dwim_new_local_branch &&
1197                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1198                         !opts.new_branch;
1199                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1200                                              &new, &opts.source_tree,
1201                                              rev, &opts.new_branch);
1202                 argv += n;
1203                 argc -= n;
1204         }
1205
1206         if (argc) {
1207                 parse_pathspec(&opts.pathspec, 0,
1208                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1209                                prefix, argv);
1210
1211                 if (!opts.pathspec.nr)
1212                         die(_("invalid path specification"));
1213
1214                 /*
1215                  * Try to give more helpful suggestion.
1216                  * new_branch && argc > 1 will be caught later.
1217                  */
1218                 if (opts.new_branch && argc == 1)
1219                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1220                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1221                             opts.new_branch, argv[0]);
1222
1223                 if (opts.force_detach)
1224                         die(_("git checkout: --detach does not take a path argument '%s'"),
1225                             argv[0]);
1226
1227                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1228                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1229                               "checking out of the index."));
1230         }
1231
1232         if (opts.new_branch) {
1233                 struct strbuf buf = STRBUF_INIT;
1234
1235                 opts.branch_exists =
1236                         validate_new_branchname(opts.new_branch, &buf,
1237                                                 !!opts.new_branch_force,
1238                                                 !!opts.new_branch_force);
1239
1240                 strbuf_release(&buf);
1241         }
1242
1243         if (opts.patch_mode || opts.pathspec.nr)
1244                 return checkout_paths(&opts, new.name);
1245         else
1246                 return checkout_branch(&opts, &new);
1247 }