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         int pos;
  71
  72         if (S_ISDIR(mode))
  73                 return READ_TREE_RECURSIVE;
  74
  75         len = baselen + strlen(pathname);
  76         ce = xcalloc(1, cache_entry_size(len));
  77         hashcpy(ce->sha1, sha1);
  78         memcpy(ce->name, base, baselen);
  79         memcpy(ce->name + baselen, pathname, len - baselen);
  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         int newfd;
 247         struct lock_file *lock_file;
 248
 249         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 250                 die(_("'%s' cannot be used with updating paths"), "--track");
 251
 252         if (opts->new_branch_log)
 253                 die(_("'%s' cannot be used with updating paths"), "-l");
 254
 255         if (opts->force && opts->patch_mode)
 256                 die(_("'%s' cannot be used with updating paths"), "-f");
 257
 258         if (opts->force_detach)
 259                 die(_("'%s' cannot be used with updating paths"), "--detach");
 260
 261         if (opts->merge && opts->patch_mode)
 262                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 263
 264         if (opts->force && opts->merge)
 265                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 266
 267         if (opts->new_branch)
 268                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 269                     opts->new_branch);
 270
 271         if (opts->patch_mode)
 272                 return run_add_interactive(revision, "--patch=checkout",
 273                                            &opts->pathspec);
 274
 275         lock_file = xcalloc(1, sizeof(struct lock_file));
 276
 277         newfd = hold_locked_index(lock_file, 1);
 278         if (read_cache_preload(&opts->pathspec) < 0)
 279                 return error(_("corrupt index file"));
 280
 281         if (opts->source_tree)
 282                 read_tree_some(opts->source_tree, &opts->pathspec);
 283
 284         ps_matched = xcalloc(1, opts->pathspec.nr);
 285
 286         /*
 287          * Make sure all pathspecs participated in locating the paths
 288          * to be checked out.
 289          */
 290         for (pos = 0; pos < active_nr; pos++) {
 291                 struct cache_entry *ce = active_cache[pos];
 292                 ce->ce_flags &= ~CE_MATCHED;
 293                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 294                         continue;
 295                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 296                         /*
 297                          * "git checkout tree-ish -- path", but this entry
 298                          * is in the original index; it will not be checked
 299                          * out to the working tree and it does not matter
 300                          * if pathspec matched this entry.  We will not do
 301                          * anything to this entry at all.
 302                          */
 303                         continue;
 304                 /*
 305                  * Either this entry came from the tree-ish we are
 306                  * checking the paths out of, or we are checking out
 307                  * of the index.
 308                  *
 309                  * If it comes from the tree-ish, we already know it
 310                  * matches the pathspec and could just stamp
 311                  * CE_MATCHED to it from update_some(). But we still
 312                  * need ps_matched and read_tree_recursive (and
 313                  * eventually tree_entry_interesting) cannot fill
 314                  * ps_matched yet. Once it can, we can avoid calling
 315                  * match_pathspec() for _all_ entries when
 316                  * opts->source_tree != NULL.
 317                  */
 318                 if (match_pathspec_depth(&opts->pathspec, ce->name, ce_namelen(ce),
 319                                    0, ps_matched))
 320                         ce->ce_flags |= CE_MATCHED;
 321         }
 322
 323         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 324                 free(ps_matched);
 325                 return 1;
 326         }
 327         free(ps_matched);
 328
 329         /* "checkout -m path" to recreate conflicted state */
 330         if (opts->merge)
 331                 unmerge_marked_index(&the_index);
 332
 333         /* Any unmerged paths? */
 334         for (pos = 0; pos < active_nr; pos++) {
 335                 const struct cache_entry *ce = active_cache[pos];
 336                 if (ce->ce_flags & CE_MATCHED) {
 337                         if (!ce_stage(ce))
 338                                 continue;
 339                         if (opts->force) {
 340                                 warning(_("path '%s' is unmerged"), ce->name);
 341                         } else if (opts->writeout_stage) {
 342                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 343                         } else if (opts->merge) {
 344                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 345                         } else {
 346                                 errs = 1;
 347                                 error(_("path '%s' is unmerged"), ce->name);
 348                         }
 349                         pos = skip_same_name(ce, pos) - 1;
 350                 }
 351         }
 352         if (errs)
 353                 return 1;
 354
 355         /* Now we are committed to check them out */
 356         memset(&state, 0, sizeof(state));
 357         state.force = 1;
 358         state.refresh_cache = 1;
 359         for (pos = 0; pos < active_nr; pos++) {
 360                 struct cache_entry *ce = active_cache[pos];
 361                 if (ce->ce_flags & CE_MATCHED) {
 362                         if (!ce_stage(ce)) {
 363                                 errs |= checkout_entry(ce, &state, NULL);
 364                                 continue;
 365                         }
 366                         if (opts->writeout_stage)
 367                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 368                         else if (opts->merge)
 369                                 errs |= checkout_merged(pos, &state);
 370                         pos = skip_same_name(ce, pos) - 1;
 371                 }
 372         }
 373
 374         if (write_cache(newfd, active_cache, active_nr) ||
 375             commit_locked_index(lock_file))
 376                 die(_("unable to write new index file"));
 377
 378         read_ref_full("HEAD", rev, 0, &flag);
 379         head = lookup_commit_reference_gently(rev, 1);
 380
 381         errs |= post_checkout_hook(head, head, 0);
 382         return errs;
 383 }
 384
 385 static void show_local_changes(struct object *head,
 386                                const struct diff_options *opts)
 387 {
 388         struct rev_info rev;
 389         /* I think we want full paths, even if we're in a subdirectory. */
 390         init_revisions(&rev, NULL);
 391         rev.diffopt.flags = opts->flags;
 392         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 393         diff_setup_done(&rev.diffopt);
 394         add_pending_object(&rev, head, NULL);
 395         run_diff_index(&rev, 0);
 396 }
 397
 398 static void describe_detached_head(const char *msg, struct commit *commit)
 399 {
 400         struct strbuf sb = STRBUF_INIT;
 401         parse_commit(commit);
 402         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 403         fprintf(stderr, "%s %s... %s\n", msg,
 404                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 405         strbuf_release(&sb);
 406 }
 407
 408 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 409                       int worktree, int *writeout_error)
 410 {
 411         struct unpack_trees_options opts;
 412         struct tree_desc tree_desc;
 413
 414         memset(&opts, 0, sizeof(opts));
 415         opts.head_idx = -1;
 416         opts.update = worktree;
 417         opts.skip_unmerged = !worktree;
 418         opts.reset = 1;
 419         opts.merge = 1;
 420         opts.fn = oneway_merge;
 421         opts.verbose_update = !o->quiet && isatty(2);
 422         opts.src_index = &the_index;
 423         opts.dst_index = &the_index;
 424         parse_tree(tree);
 425         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 426         switch (unpack_trees(1, &tree_desc, &opts)) {
 427         case -2:
 428                 *writeout_error = 1;
 429                 /*
 430                  * We return 0 nevertheless, as the index is all right
 431                  * and more importantly we have made best efforts to
 432                  * update paths in the work tree, and we cannot revert
 433                  * them.
 434                  */
 435         case 0:
 436                 return 0;
 437         default:
 438                 return 128;
 439         }
 440 }
 441
 442 struct branch_info {
 443         const char *name; /* The short name used */
 444         const char *path; /* The full name of a real branch */
 445         struct commit *commit; /* The named commit */
 446 };
 447
 448 static void setup_branch_path(struct branch_info *branch)
 449 {
 450         struct strbuf buf = STRBUF_INIT;
 451
 452         strbuf_branchname(&buf, branch->name);
 453         if (strcmp(buf.buf, branch->name))
 454                 branch->name = xstrdup(buf.buf);
 455         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 456         branch->path = strbuf_detach(&buf, NULL);
 457 }
 458
 459 static int merge_working_tree(const struct checkout_opts *opts,
 460                               struct branch_info *old,
 461                               struct branch_info *new,
 462                               int *writeout_error)
 463 {
 464         int ret;
 465         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 466         int newfd = hold_locked_index(lock_file, 1);
 467
 468         if (read_cache_preload(NULL) < 0)
 469                 return error(_("corrupt index file"));
 470
 471         resolve_undo_clear();
 472         if (opts->force) {
 473                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 474                 if (ret)
 475                         return ret;
 476         } else {
 477                 struct tree_desc trees[2];
 478                 struct tree *tree;
 479                 struct unpack_trees_options topts;
 480
 481                 memset(&topts, 0, sizeof(topts));
 482                 topts.head_idx = -1;
 483                 topts.src_index = &the_index;
 484                 topts.dst_index = &the_index;
 485
 486                 setup_unpack_trees_porcelain(&topts, "checkout");
 487
 488                 refresh_cache(REFRESH_QUIET);
 489
 490                 if (unmerged_cache()) {
 491                         error(_("you need to resolve your current index first"));
 492                         return 1;
 493                 }
 494
 495                 /* 2-way merge to the new branch */
 496                 topts.initial_checkout = is_cache_unborn();
 497                 topts.update = 1;
 498                 topts.merge = 1;
 499                 topts.gently = opts->merge && old->commit;
 500                 topts.verbose_update = !opts->quiet && isatty(2);
 501                 topts.fn = twoway_merge;
 502                 if (opts->overwrite_ignore) {
 503                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 504                         topts.dir->flags |= DIR_SHOW_IGNORED;
 505                         setup_standard_excludes(topts.dir);
 506                 }
 507                 tree = parse_tree_indirect(old->commit ?
 508                                            old->commit->object.sha1 :
 509                                            EMPTY_TREE_SHA1_BIN);
 510                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 511                 tree = parse_tree_indirect(new->commit->object.sha1);
 512                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 513
 514                 ret = unpack_trees(2, trees, &topts);
 515                 if (ret == -1) {
 516                         /*
 517                          * Unpack couldn't do a trivial merge; either
 518                          * give up or do a real merge, depending on
 519                          * whether the merge flag was used.
 520                          */
 521                         struct tree *result;
 522                         struct tree *work;
 523                         struct merge_options o;
 524                         if (!opts->merge)
 525                                 return 1;
 526
 527                         /*
 528                          * Without old->commit, the below is the same as
 529                          * the two-tree unpack we already tried and failed.
 530                          */
 531                         if (!old->commit)
 532                                 return 1;
 533
 534                         /* Do more real merge */
 535
 536                         /*
 537                          * We update the index fully, then write the
 538                          * tree from the index, then merge the new
 539                          * branch with the current tree, with the old
 540                          * branch as the base. Then we reset the index
 541                          * (but not the working tree) to the new
 542                          * branch, leaving the working tree as the
 543                          * merged version, but skipping unmerged
 544                          * entries in the index.
 545                          */
 546
 547                         add_files_to_cache(NULL, NULL, 0);
 548                         /*
 549                          * NEEDSWORK: carrying over local changes
 550                          * when branches have different end-of-line
 551                          * normalization (or clean+smudge rules) is
 552                          * a pain; plumb in an option to set
 553                          * o.renormalize?
 554                          */
 555                         init_merge_options(&o);
 556                         o.verbosity = 0;
 557                         work = write_tree_from_memory(&o);
 558
 559                         ret = reset_tree(new->commit->tree, opts, 1,
 560                                          writeout_error);
 561                         if (ret)
 562                                 return ret;
 563                         o.ancestor = old->name;
 564                         o.branch1 = new->name;
 565                         o.branch2 = "local";
 566                         merge_trees(&o, new->commit->tree, work,
 567                                 old->commit->tree, &result);
 568                         ret = reset_tree(new->commit->tree, opts, 0,
 569                                          writeout_error);
 570                         if (ret)
 571                                 return ret;
 572                 }
 573         }
 574
 575         if (write_cache(newfd, active_cache, active_nr) ||
 576             commit_locked_index(lock_file))
 577                 die(_("unable to write new index file"));
 578
 579         if (!opts->force && !opts->quiet)
 580                 show_local_changes(&new->commit->object, &opts->diff_options);
 581
 582         return 0;
 583 }
 584
 585 static void report_tracking(struct branch_info *new)
 586 {
 587         struct strbuf sb = STRBUF_INIT;
 588         struct branch *branch = branch_get(new->name);
 589
 590         if (!format_tracking_info(branch, &sb))
 591                 return;
 592         fputs(sb.buf, stdout);
 593         strbuf_release(&sb);
 594 }
 595
 596 static void update_refs_for_switch(const struct checkout_opts *opts,
 597                                    struct branch_info *old,
 598                                    struct branch_info *new)
 599 {
 600         struct strbuf msg = STRBUF_INIT;
 601         const char *old_desc, *reflog_msg;
 602         if (opts->new_branch) {
 603                 if (opts->new_orphan_branch) {
 604                         if (opts->new_branch_log && !log_all_ref_updates) {
 605                                 int temp;
 606                                 char log_file[PATH_MAX];
 607                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 608
 609                                 temp = log_all_ref_updates;
 610                                 log_all_ref_updates = 1;
 611                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 612                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 613                                             opts->new_orphan_branch);
 614                                         log_all_ref_updates = temp;
 615                                         return;
 616                                 }
 617                                 log_all_ref_updates = temp;
 618                         }
 619                 }
 620                 else
 621                         create_branch(old->name, opts->new_branch, new->name,
 622                                       opts->new_branch_force ? 1 : 0,
 623                                       opts->new_branch_log,
 624                                       opts->new_branch_force ? 1 : 0,
 625                                       opts->quiet,
 626                                       opts->track);
 627                 new->name = opts->new_branch;
 628                 setup_branch_path(new);
 629         }
 630
 631         old_desc = old->name;
 632         if (!old_desc && old->commit)
 633                 old_desc = sha1_to_hex(old->commit->object.sha1);
 634
 635         reflog_msg = getenv("GIT_REFLOG_ACTION");
 636         if (!reflog_msg)
 637                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 638                         old_desc ? old_desc : "(invalid)", new->name);
 639         else
 640                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 641
 642         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 643                 /* Nothing to do. */
 644         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 645                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 646                            REF_NODEREF, DIE_ON_ERR);
 647                 if (!opts->quiet) {
 648                         if (old->path && advice_detached_head)
 649                                 detach_advice(new->name);
 650                         describe_detached_head(_("HEAD is now at"), new->commit);
 651                 }
 652         } else if (new->path) { /* Switch branches. */
 653                 create_symref("HEAD", new->path, msg.buf);
 654                 if (!opts->quiet) {
 655                         if (old->path && !strcmp(new->path, old->path)) {
 656                                 if (opts->new_branch_force)
 657                                         fprintf(stderr, _("Reset branch '%s'\n"),
 658                                                 new->name);
 659                                 else
 660                                         fprintf(stderr, _("Already on '%s'\n"),
 661                                                 new->name);
 662                         } else if (opts->new_branch) {
 663                                 if (opts->branch_exists)
 664                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 665                                 else
 666                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 667                         } else {
 668                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 669                                         new->name);
 670                         }
 671                 }
 672                 if (old->path && old->name) {
 673                         char log_file[PATH_MAX], ref_file[PATH_MAX];
 674
 675                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
 676                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
 677                         if (!file_exists(ref_file) && file_exists(log_file))
 678                                 remove_path(log_file);
 679                 }
 680         }
 681         remove_branch_state();
 682         strbuf_release(&msg);
 683         if (!opts->quiet &&
 684             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 685                 report_tracking(new);
 686 }
 687
 688 static int add_pending_uninteresting_ref(const char *refname,
 689                                          const unsigned char *sha1,
 690                                          int flags, void *cb_data)
 691 {
 692         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 693         return 0;
 694 }
 695
 696 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 697 {
 698         parse_commit(commit);
 699         strbuf_addstr(sb, "  ");
 700         strbuf_addstr(sb,
 701                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 702         strbuf_addch(sb, ' ');
 703         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 704         strbuf_addch(sb, '\n');
 705 }
 706
 707 #define ORPHAN_CUTOFF 4
 708 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 709 {
 710         struct commit *c, *last = NULL;
 711         struct strbuf sb = STRBUF_INIT;
 712         int lost = 0;
 713         while ((c = get_revision(revs)) != NULL) {
 714                 if (lost < ORPHAN_CUTOFF)
 715                         describe_one_orphan(&sb, c);
 716                 last = c;
 717                 lost++;
 718         }
 719         if (ORPHAN_CUTOFF < lost) {
 720                 int more = lost - ORPHAN_CUTOFF;
 721                 if (more == 1)
 722                         describe_one_orphan(&sb, last);
 723                 else
 724                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 725         }
 726
 727         fprintf(stderr,
 728                 Q_(
 729                 /* The singular version */
 730                 "Warning: you are leaving %d commit behind, "
 731                 "not connected to\n"
 732                 "any of your branches:\n\n"
 733                 "%s\n",
 734                 /* The plural version */
 735                 "Warning: you are leaving %d commits behind, "
 736                 "not connected to\n"
 737                 "any of your branches:\n\n"
 738                 "%s\n",
 739                 /* Give ngettext() the count */
 740                 lost),
 741                 lost,
 742                 sb.buf);
 743         strbuf_release(&sb);
 744
 745         if (advice_detached_head)
 746                 fprintf(stderr,
 747                         _(
 748                         "If you want to keep them by creating a new branch, "
 749                         "this may be a good time\nto do so with:\n\n"
 750                         " git branch new_branch_name %s\n\n"),
 751                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 752 }
 753
 754 /*
 755  * We are about to leave commit that was at the tip of a detached
 756  * HEAD.  If it is not reachable from any ref, this is the last chance
 757  * for the user to do so without resorting to reflog.
 758  */
 759 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 760 {
 761         struct rev_info revs;
 762         struct object *object = &old->object;
 763         struct object_array refs;
 764
 765         init_revisions(&revs, NULL);
 766         setup_revisions(0, NULL, &revs, NULL);
 767
 768         object->flags &= ~UNINTERESTING;
 769         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 770
 771         for_each_ref(add_pending_uninteresting_ref, &revs);
 772         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 773
 774         refs = revs.pending;
 775         revs.leak_pending = 1;
 776
 777         if (prepare_revision_walk(&revs))
 778                 die(_("internal error in revision walk"));
 779         if (!(old->object.flags & UNINTERESTING))
 780                 suggest_reattach(old, &revs);
 781         else
 782                 describe_detached_head(_("Previous HEAD position was"), old);
 783
 784         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 785         free(refs.objects);
 786 }
 787
 788 static int switch_branches(const struct checkout_opts *opts,
 789                            struct branch_info *new)
 790 {
 791         int ret = 0;
 792         struct branch_info old;
 793         void *path_to_free;
 794         unsigned char rev[20];
 795         int flag, writeout_error = 0;
 796         memset(&old, 0, sizeof(old));
 797         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
 798         old.commit = lookup_commit_reference_gently(rev, 1);
 799         if (!(flag & REF_ISSYMREF))
 800                 old.path = NULL;
 801
 802         if (old.path && !prefixcmp(old.path, "refs/heads/"))
 803                 old.name = old.path + strlen("refs/heads/");
 804
 805         if (!new->name) {
 806                 new->name = "HEAD";
 807                 new->commit = old.commit;
 808                 if (!new->commit)
 809                         die(_("You are on a branch yet to be born"));
 810                 parse_commit(new->commit);
 811         }
 812
 813         ret = merge_working_tree(opts, &old, new, &writeout_error);
 814         if (ret) {
 815                 free(path_to_free);
 816                 return ret;
 817         }
 818
 819         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 820                 orphaned_commit_warning(old.commit, new->commit);
 821
 822         update_refs_for_switch(opts, &old, new);
 823
 824         ret = post_checkout_hook(old.commit, new->commit, 1);
 825         free(path_to_free);
 826         return ret || writeout_error;
 827 }
 828
 829 static int git_checkout_config(const char *var, const char *value, void *cb)
 830 {
 831         if (!strcmp(var, "diff.ignoresubmodules")) {
 832                 struct checkout_opts *opts = cb;
 833                 handle_ignore_submodules_arg(&opts->diff_options, value);
 834                 return 0;
 835         }
 836
 837         if (!prefixcmp(var, "submodule."))
 838                 return parse_submodule_config_option(var, value);
 839
 840         return git_xmerge_config(var, value, NULL);
 841 }
 842
 843 struct tracking_name_data {
 844         /* const */ char *src_ref;
 845         char *dst_ref;
 846         unsigned char *dst_sha1;
 847         int unique;
 848 };
 849
 850 static int check_tracking_name(struct remote *remote, void *cb_data)
 851 {
 852         struct tracking_name_data *cb = cb_data;
 853         struct refspec query;
 854         memset(&query, 0, sizeof(struct refspec));
 855         query.src = cb->src_ref;
 856         if (remote_find_tracking(remote, &query) ||
 857             get_sha1(query.dst, cb->dst_sha1)) {
 858                 free(query.dst);
 859                 return 0;
 860         }
 861         if (cb->dst_ref) {
 862                 free(query.dst);
 863                 cb->unique = 0;
 864                 return 0;
 865         }
 866         cb->dst_ref = query.dst;
 867         return 0;
 868 }
 869
 870 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 871 {
 872         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 873         char src_ref[PATH_MAX];
 874         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 875         cb_data.src_ref = src_ref;
 876         cb_data.dst_sha1 = sha1;
 877         for_each_remote(check_tracking_name, &cb_data);
 878         if (cb_data.unique)
 879                 return cb_data.dst_ref;
 880         free(cb_data.dst_ref);
 881         return NULL;
 882 }
 883
 884 static int parse_branchname_arg(int argc, const char **argv,
 885                                 int dwim_new_local_branch_ok,
 886                                 struct branch_info *new,
 887                                 struct tree **source_tree,
 888                                 unsigned char rev[20],
 889                                 const char **new_branch)
 890 {
 891         int argcount = 0;
 892         unsigned char branch_rev[20];
 893         const char *arg;
 894         int dash_dash_pos;
 895         int has_dash_dash = 0;
 896         int i;
 897
 898         /*
 899          * case 1: git checkout <ref> -- [<paths>]
 900          *
 901          *   <ref> must be a valid tree, everything after the '--' must be
 902          *   a path.
 903          *
 904          * case 2: git checkout -- [<paths>]
 905          *
 906          *   everything after the '--' must be paths.
 907          *
 908          * case 3: git checkout <something> [--]
 909          *
 910          *   (a) If <something> is a commit, that is to
 911          *       switch to the branch or detach HEAD at it.  As a special case,
 912          *       if <something> is A...B (missing A or B means HEAD but you can
 913          *       omit at most one side), and if there is a unique merge base
 914          *       between A and B, A...B names that merge base.
 915          *
 916          *   (b) If <something> is _not_ a commit, either "--" is present
 917          *       or <something> is not a path, no -t nor -b was given, and
 918          *       and there is a tracking branch whose name is <something>
 919          *       in one and only one remote, then this is a short-hand to
 920          *       fork local <something> from that remote-tracking branch.
 921          *
 922          *   (c) Otherwise, if "--" is present, treat it like case (1).
 923          *
 924          *   (d) Otherwise :
 925          *       - if it's a reference, treat it like case (1)
 926          *       - else if it's a path, treat it like case (2)
 927          *       - else: fail.
 928          *
 929          * case 4: git checkout <something> <paths>
 930          *
 931          *   The first argument must not be ambiguous.
 932          *   - If it's *only* a reference, treat it like case (1).
 933          *   - If it's only a path, treat it like case (2).
 934          *   - else: fail.
 935          *
 936          */
 937         if (!argc)
 938                 return 0;
 939
 940         arg = argv[0];
 941         dash_dash_pos = -1;
 942         for (i = 0; i < argc; i++) {
 943                 if (!strcmp(argv[i], "--")) {
 944                         dash_dash_pos = i;
 945                         break;
 946                 }
 947         }
 948         if (dash_dash_pos == 0)
 949                 return 1; /* case (2) */
 950         else if (dash_dash_pos == 1)
 951                 has_dash_dash = 1; /* case (3) or (1) */
 952         else if (dash_dash_pos >= 2)
 953                 die(_("only one reference expected, %d given."), dash_dash_pos);
 954
 955         if (!strcmp(arg, "-"))
 956                 arg = "@{-1}";
 957
 958         if (get_sha1_mb(arg, rev)) {
 959                 /*
 960                  * Either case (3) or (4), with <something> not being
 961                  * a commit, or an attempt to use case (1) with an
 962                  * invalid ref.
 963                  *
 964                  * It's likely an error, but we need to find out if
 965                  * we should auto-create the branch, case (3).(b).
 966                  */
 967                 int recover_with_dwim = dwim_new_local_branch_ok;
 968
 969                 if (check_filename(NULL, arg) && !has_dash_dash)
 970                         recover_with_dwim = 0;
 971                 /*
 972                  * Accept "git checkout foo" and "git checkout foo --"
 973                  * as candidates for dwim.
 974                  */
 975                 if (!(argc == 1 && !has_dash_dash) &&
 976                     !(argc == 2 && has_dash_dash))
 977                         recover_with_dwim = 0;
 978
 979                 if (recover_with_dwim) {
 980                         const char *remote = unique_tracking_name(arg, rev);
 981                         if (remote) {
 982                                 *new_branch = arg;
 983                                 arg = remote;
 984                                 /* DWIMmed to create local branch, case (3).(b) */
 985                         } else {
 986                                 recover_with_dwim = 0;
 987                         }
 988                 }
 989
 990                 if (!recover_with_dwim) {
 991                         if (has_dash_dash)
 992                                 die(_("invalid reference: %s"), arg);
 993                         return argcount;
 994                 }
 995         }
 996
 997         /* we can't end up being in (2) anymore, eat the argument */
 998         argcount++;
 999         argv++;
1000         argc--;
1001
1002         new->name = arg;
1003         setup_branch_path(new);
1004
1005         if (!check_refname_format(new->path, 0) &&
1006             !read_ref(new->path, branch_rev))
1007                 hashcpy(rev, branch_rev);
1008         else
1009                 new->path = NULL; /* not an existing branch */
1010
1011         new->commit = lookup_commit_reference_gently(rev, 1);
1012         if (!new->commit) {
1013                 /* not a commit */
1014                 *source_tree = parse_tree_indirect(rev);
1015         } else {
1016                 parse_commit(new->commit);
1017                 *source_tree = new->commit->tree;
1018         }
1019
1020         if (!*source_tree)                   /* case (1): want a tree */
1021                 die(_("reference is not a tree: %s"), arg);
1022         if (!has_dash_dash) {/* case (3).(d) -> (1) */
1023                 /*
1024                  * Do not complain the most common case
1025                  *      git checkout branch
1026                  * even if there happen to be a file called 'branch';
1027                  * it would be extremely annoying.
1028                  */
1029                 if (argc)
1030                         verify_non_filename(NULL, arg);
1031         } else {
1032                 argcount++;
1033                 argv++;
1034                 argc--;
1035         }
1036
1037         return argcount;
1038 }
1039
1040 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1041 {
1042         int status;
1043         struct strbuf branch_ref = STRBUF_INIT;
1044
1045         if (!opts->new_branch)
1046                 die(_("You are on a branch yet to be born"));
1047         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1048         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1049         strbuf_release(&branch_ref);
1050         if (!opts->quiet)
1051                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1052                         opts->new_branch);
1053         return status;
1054 }
1055
1056 static int checkout_branch(struct checkout_opts *opts,
1057                            struct branch_info *new)
1058 {
1059         if (opts->pathspec.nr)
1060                 die(_("paths cannot be used with switching branches"));
1061
1062         if (opts->patch_mode)
1063                 die(_("'%s' cannot be used with switching branches"),
1064                     "--patch");
1065
1066         if (opts->writeout_stage)
1067                 die(_("'%s' cannot be used with switching branches"),
1068                     "--ours/--theirs");
1069
1070         if (opts->force && opts->merge)
1071                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1072
1073         if (opts->force_detach && opts->new_branch)
1074                 die(_("'%s' cannot be used with '%s'"),
1075                     "--detach", "-b/-B/--orphan");
1076
1077         if (opts->new_orphan_branch) {
1078                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1079                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1080         } else if (opts->force_detach) {
1081                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1082                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1083         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1084                 opts->track = git_branch_track;
1085
1086         if (new->name && !new->commit)
1087                 die(_("Cannot switch branch to a non-commit '%s'"),
1088                     new->name);
1089
1090         if (!new->commit && opts->new_branch) {
1091                 unsigned char rev[20];
1092                 int flag;
1093
1094                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
1095                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1096                         return switch_unborn_to_new_branch(opts);
1097         }
1098         return switch_branches(opts, new);
1099 }
1100
1101 int cmd_checkout(int argc, const char **argv, const char *prefix)
1102 {
1103         struct checkout_opts opts;
1104         struct branch_info new;
1105         char *conflict_style = NULL;
1106         int dwim_new_local_branch = 1;
1107         struct option options[] = {
1108                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1109                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1110                            N_("create and checkout a new branch")),
1111                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1112                            N_("create/reset and checkout a branch")),
1113                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1114                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1115                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1116                         BRANCH_TRACK_EXPLICIT),
1117                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new branch"), N_("new unparented branch")),
1118                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1119                             2),
1120                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1121                             3),
1122                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1123                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1124                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1125                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1126                            N_("conflict style (merge or diff3)")),
1127                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1128                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1129                          N_("do not limit pathspecs to sparse entries only")),
1130                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1131                                 N_("second guess 'git checkout no-such-branch'")),
1132                 OPT_END(),
1133         };
1134
1135         memset(&opts, 0, sizeof(opts));
1136         memset(&new, 0, sizeof(new));
1137         opts.overwrite_ignore = 1;
1138         opts.prefix = prefix;
1139
1140         gitmodules_config();
1141         git_config(git_checkout_config, &opts);
1142
1143         opts.track = BRANCH_TRACK_UNSPECIFIED;
1144
1145         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1146                              PARSE_OPT_KEEP_DASHDASH);
1147
1148         if (conflict_style) {
1149                 opts.merge = 1; /* implied */
1150                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1151         }
1152
1153         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1154                 die(_("-b, -B and --orphan are mutually exclusive"));
1155
1156         /*
1157          * From here on, new_branch will contain the branch to be checked out,
1158          * and new_branch_force and new_orphan_branch will tell us which one of
1159          * -b/-B/--orphan is being used.
1160          */
1161         if (opts.new_branch_force)
1162                 opts.new_branch = opts.new_branch_force;
1163
1164         if (opts.new_orphan_branch)
1165                 opts.new_branch = opts.new_orphan_branch;
1166
1167         /* --track without -b/-B/--orphan should DWIM */
1168         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1169                 const char *argv0 = argv[0];
1170                 if (!argc || !strcmp(argv0, "--"))
1171                         die (_("--track needs a branch name"));
1172                 if (!prefixcmp(argv0, "refs/"))
1173                         argv0 += 5;
1174                 if (!prefixcmp(argv0, "remotes/"))
1175                         argv0 += 8;
1176                 argv0 = strchr(argv0, '/');
1177                 if (!argv0 || !argv0[1])
1178                         die (_("Missing branch name; try -b"));
1179                 opts.new_branch = argv0 + 1;
1180         }
1181
1182         /*
1183          * Extract branch name from command line arguments, so
1184          * all that is left is pathspecs.
1185          *
1186          * Handle
1187          *
1188          *  1) git checkout <tree> -- [<paths>]
1189          *  2) git checkout -- [<paths>]
1190          *  3) git checkout <something> [<paths>]
1191          *
1192          * including "last branch" syntax and DWIM-ery for names of
1193          * remote branches, erroring out for invalid or ambiguous cases.
1194          */
1195         if (argc) {
1196                 unsigned char rev[20];
1197                 int dwim_ok =
1198                         !opts.patch_mode &&
1199                         dwim_new_local_branch &&
1200                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1201                         !opts.new_branch;
1202                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1203                                              &new, &opts.source_tree,
1204                                              rev, &opts.new_branch);
1205                 argv += n;
1206                 argc -= n;
1207         }
1208
1209         if (argc) {
1210                 parse_pathspec(&opts.pathspec, 0,
1211                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1212                                prefix, argv);
1213
1214                 if (!opts.pathspec.nr)
1215                         die(_("invalid path specification"));
1216
1217                 /*
1218                  * Try to give more helpful suggestion.
1219                  * new_branch && argc > 1 will be caught later.
1220                  */
1221                 if (opts.new_branch && argc == 1)
1222                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1223                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1224                             opts.new_branch, argv[0]);
1225
1226                 if (opts.force_detach)
1227                         die(_("git checkout: --detach does not take a path argument '%s'"),
1228                             argv[0]);
1229
1230                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1231                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1232                               "checking out of the index."));
1233         }
1234
1235         if (opts.new_branch) {
1236                 struct strbuf buf = STRBUF_INIT;
1237
1238                 opts.branch_exists =
1239                         validate_new_branchname(opts.new_branch, &buf,
1240                                                 !!opts.new_branch_force,
1241                                                 !!opts.new_branch_force);
1242
1243                 strbuf_release(&buf);
1244         }
1245
1246         if (opts.patch_mode || opts.pathspec.nr)
1247                 return checkout_paths(&opts, new.name);
1248         else
1249                 return checkout_branch(&opts, &new);
1250 }