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

   1 #include "builtin.h"
   2 #include "config.h"
   3 #include "checkout.h"
   4 #include "lockfile.h"
   5 #include "parse-options.h"
   6 #include "refs.h"
   7 #include "commit.h"
   8 #include "tree.h"
   9 #include "tree-walk.h"
  10 #include "cache-tree.h"
  11 #include "unpack-trees.h"
  12 #include "dir.h"
  13 #include "run-command.h"
  14 #include "merge-recursive.h"
  15 #include "branch.h"
  16 #include "diff.h"
  17 #include "revision.h"
  18 #include "remote.h"
  19 #include "blob.h"
  20 #include "xdiff-interface.h"
  21 #include "ll-merge.h"
  22 #include "resolve-undo.h"
  23 #include "submodule-config.h"
  24 #include "submodule.h"
  25
  26 static const char * const checkout_usage[] = {
  27         N_("git checkout [<options>] <branch>"),
  28         N_("git checkout [<options>] [<branch>] -- <file>..."),
  29         NULL,
  30 };
  31
  32 struct checkout_opts {
  33         int patch_mode;
  34         int quiet;
  35         int merge;
  36         int force;
  37         int force_detach;
  38         int writeout_stage;
  39         int overwrite_ignore;
  40         int ignore_skipworktree;
  41         int ignore_other_worktrees;
  42         int show_progress;
  43
  44         const char *new_branch;
  45         const char *new_branch_force;
  46         const char *new_orphan_branch;
  47         int new_branch_log;
  48         enum branch_track track;
  49         struct diff_options diff_options;
  50
  51         int branch_exists;
  52         const char *prefix;
  53         struct pathspec pathspec;
  54         struct tree *source_tree;
  55 };
  56
  57 static int post_checkout_hook(struct commit *old, struct commit *new,
  58                               int changed)
  59 {
  60         return run_hook_le(NULL, "post-checkout",
  61                            oid_to_hex(old ? &old->object.oid : &null_oid),
  62                            oid_to_hex(new ? &new->object.oid : &null_oid),
  63                            changed ? "1" : "0", NULL);
  64         /* "new" can be NULL when checking out from the index before
  65            a commit exists. */
  66
  67 }
  68
  69 static int update_some(const unsigned char *sha1, struct strbuf *base,
  70                 const char *pathname, unsigned mode, int stage, void *context)
  71 {
  72         int len;
  73         struct cache_entry *ce;
  74         int pos;
  75
  76         if (S_ISDIR(mode))
  77                 return READ_TREE_RECURSIVE;
  78
  79         len = base->len + strlen(pathname);
  80         ce = xcalloc(1, cache_entry_size(len));
  81         hashcpy(ce->oid.hash, sha1);
  82         memcpy(ce->name, base->buf, base->len);
  83         memcpy(ce->name + base->len, pathname, len - base->len);
  84         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  85         ce->ce_namelen = len;
  86         ce->ce_mode = create_ce_mode(mode);
  87
  88         /*
  89          * If the entry is the same as the current index, we can leave the old
  90          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  91          * do the right thing.
  92          */
  93         pos = cache_name_pos(ce->name, ce->ce_namelen);
  94         if (pos >= 0) {
  95                 struct cache_entry *old = active_cache[pos];
  96                 if (ce->ce_mode == old->ce_mode &&
  97                     !oidcmp(&ce->oid, &old->oid)) {
  98                         old->ce_flags |= CE_UPDATE;
  99                         free(ce);
 100                         return 0;
 101                 }
 102         }
 103
 104         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 105         return 0;
 106 }
 107
 108 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 109 {
 110         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 111
 112         /* update the index with the given tree's info
 113          * for all args, expanding wildcards, and exit
 114          * with any non-zero return code.
 115          */
 116         return 0;
 117 }
 118
 119 static int skip_same_name(const struct cache_entry *ce, int pos)
 120 {
 121         while (++pos < active_nr &&
 122                !strcmp(active_cache[pos]->name, ce->name))
 123                 ; /* skip */
 124         return pos;
 125 }
 126
 127 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 128 {
 129         while (pos < active_nr &&
 130                !strcmp(active_cache[pos]->name, ce->name)) {
 131                 if (ce_stage(active_cache[pos]) == stage)
 132                         return 0;
 133                 pos++;
 134         }
 135         if (stage == 2)
 136                 return error(_("path '%s' does not have our version"), ce->name);
 137         else
 138                 return error(_("path '%s' does not have their version"), ce->name);
 139 }
 140
 141 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 142 {
 143         unsigned seen = 0;
 144         const char *name = ce->name;
 145
 146         while (pos < active_nr) {
 147                 ce = active_cache[pos];
 148                 if (strcmp(name, ce->name))
 149                         break;
 150                 seen |= (1 << ce_stage(ce));
 151                 pos++;
 152         }
 153         if ((stages & seen) != stages)
 154                 return error(_("path '%s' does not have all necessary versions"),
 155                              name);
 156         return 0;
 157 }
 158
 159 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 160                           const struct checkout *state)
 161 {
 162         while (pos < active_nr &&
 163                !strcmp(active_cache[pos]->name, ce->name)) {
 164                 if (ce_stage(active_cache[pos]) == stage)
 165                         return checkout_entry(active_cache[pos], state, NULL);
 166                 pos++;
 167         }
 168         if (stage == 2)
 169                 return error(_("path '%s' does not have our version"), ce->name);
 170         else
 171                 return error(_("path '%s' does not have their version"), ce->name);
 172 }
 173
 174 static int checkout_merged(int pos, const struct checkout *state)
 175 {
 176         struct cache_entry *ce = active_cache[pos];
 177         const char *path = ce->name;
 178         mmfile_t ancestor, ours, theirs;
 179         int status;
 180         struct object_id oid;
 181         mmbuffer_t result_buf;
 182         struct object_id threeway[3];
 183         unsigned mode = 0;
 184
 185         memset(threeway, 0, sizeof(threeway));
 186         while (pos < active_nr) {
 187                 int stage;
 188                 stage = ce_stage(ce);
 189                 if (!stage || strcmp(path, ce->name))
 190                         break;
 191                 oidcpy(&threeway[stage - 1], &ce->oid);
 192                 if (stage == 2)
 193                         mode = create_ce_mode(ce->ce_mode);
 194                 pos++;
 195                 ce = active_cache[pos];
 196         }
 197         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 198                 return error(_("path '%s' does not have necessary versions"), path);
 199
 200         read_mmblob(&ancestor, &threeway[0]);
 201         read_mmblob(&ours, &threeway[1]);
 202         read_mmblob(&theirs, &threeway[2]);
 203
 204         /*
 205          * NEEDSWORK: re-create conflicts from merges with
 206          * merge.renormalize set, too
 207          */
 208         status = ll_merge(&result_buf, path, &ancestor, "base",
 209                           &ours, "ours", &theirs, "theirs", NULL);
 210         free(ancestor.ptr);
 211         free(ours.ptr);
 212         free(theirs.ptr);
 213         if (status < 0 || !result_buf.ptr) {
 214                 free(result_buf.ptr);
 215                 return error(_("path '%s': cannot merge"), path);
 216         }
 217
 218         /*
 219          * NEEDSWORK:
 220          * There is absolutely no reason to write this as a blob object
 221          * and create a phony cache entry.  This hack is primarily to get
 222          * to the write_entry() machinery that massages the contents to
 223          * work-tree format and writes out which only allows it for a
 224          * cache entry.  The code in write_entry() needs to be refactored
 225          * to allow us to feed a <buffer, size, mode> instead of a cache
 226          * entry.  Such a refactoring would help merge_recursive as well
 227          * (it also writes the merge result to the object database even
 228          * when it may contain conflicts).
 229          */
 230         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 231                 die(_("Unable to add merge result for '%s'"), path);
 232         free(result_buf.ptr);
 233         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
 234         if (!ce)
 235                 die(_("make_cache_entry failed for path '%s'"), path);
 236         status = checkout_entry(ce, state, NULL);
 237         free(ce);
 238         return status;
 239 }
 240
 241 static int checkout_paths(const struct checkout_opts *opts,
 242                           const char *revision)
 243 {
 244         int pos;
 245         struct checkout state = CHECKOUT_INIT;
 246         static char *ps_matched;
 247         struct object_id rev;
 248         struct commit *head;
 249         int errs = 0;
 250         struct lock_file lock_file = LOCK_INIT;
 251
 252         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 253                 die(_("'%s' cannot be used with updating paths"), "--track");
 254
 255         if (opts->new_branch_log)
 256                 die(_("'%s' cannot be used with updating paths"), "-l");
 257
 258         if (opts->force && opts->patch_mode)
 259                 die(_("'%s' cannot be used with updating paths"), "-f");
 260
 261         if (opts->force_detach)
 262                 die(_("'%s' cannot be used with updating paths"), "--detach");
 263
 264         if (opts->merge && opts->patch_mode)
 265                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 266
 267         if (opts->force && opts->merge)
 268                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 269
 270         if (opts->new_branch)
 271                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 272                     opts->new_branch);
 273
 274         if (opts->patch_mode)
 275                 return run_add_interactive(revision, "--patch=checkout",
 276                                            &opts->pathspec);
 277
 278         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 279         if (read_cache_preload(&opts->pathspec) < 0)
 280                 return error(_("index file corrupt"));
 281
 282         if (opts->source_tree)
 283                 read_tree_some(opts->source_tree, &opts->pathspec);
 284
 285         ps_matched = xcalloc(opts->pathspec.nr, 1);
 286
 287         /*
 288          * Make sure all pathspecs participated in locating the paths
 289          * to be checked out.
 290          */
 291         for (pos = 0; pos < active_nr; pos++) {
 292                 struct cache_entry *ce = active_cache[pos];
 293                 ce->ce_flags &= ~CE_MATCHED;
 294                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 295                         continue;
 296                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 297                         /*
 298                          * "git checkout tree-ish -- path", but this entry
 299                          * is in the original index; it will not be checked
 300                          * out to the working tree and it does not matter
 301                          * if pathspec matched this entry.  We will not do
 302                          * anything to this entry at all.
 303                          */
 304                         continue;
 305                 /*
 306                  * Either this entry came from the tree-ish we are
 307                  * checking the paths out of, or we are checking out
 308                  * of the index.
 309                  *
 310                  * If it comes from the tree-ish, we already know it
 311                  * matches the pathspec and could just stamp
 312                  * CE_MATCHED to it from update_some(). But we still
 313                  * need ps_matched and read_tree_recursive (and
 314                  * eventually tree_entry_interesting) cannot fill
 315                  * ps_matched yet. Once it can, we can avoid calling
 316                  * match_pathspec() for _all_ entries when
 317                  * opts->source_tree != NULL.
 318                  */
 319                 if (ce_path_match(ce, &opts->pathspec, 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         state.force = 1;
 357         state.refresh_cache = 1;
 358         state.istate = &the_index;
 359
 360         enable_delayed_checkout(&state);
 361         for (pos = 0; pos < active_nr; pos++) {
 362                 struct cache_entry *ce = active_cache[pos];
 363                 if (ce->ce_flags & CE_MATCHED) {
 364                         if (!ce_stage(ce)) {
 365                                 errs |= checkout_entry(ce, &state, NULL);
 366                                 continue;
 367                         }
 368                         if (opts->writeout_stage)
 369                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 370                         else if (opts->merge)
 371                                 errs |= checkout_merged(pos, &state);
 372                         pos = skip_same_name(ce, pos) - 1;
 373                 }
 374         }
 375         errs |= finish_delayed_checkout(&state);
 376
 377         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 378                 die(_("unable to write new index file"));
 379
 380         read_ref_full("HEAD", 0, &rev, NULL);
 381         head = lookup_commit_reference_gently(&rev, 1);
 382
 383         errs |= post_checkout_hook(head, head, 0);
 384         return errs;
 385 }
 386
 387 static void show_local_changes(struct object *head,
 388                                const struct diff_options *opts)
 389 {
 390         struct rev_info rev;
 391         /* I think we want full paths, even if we're in a subdirectory. */
 392         init_revisions(&rev, NULL);
 393         rev.diffopt.flags = opts->flags;
 394         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 395         diff_setup_done(&rev.diffopt);
 396         add_pending_object(&rev, head, NULL);
 397         run_diff_index(&rev, 0);
 398 }
 399
 400 static void describe_detached_head(const char *msg, struct commit *commit)
 401 {
 402         struct strbuf sb = STRBUF_INIT;
 403
 404         if (!parse_commit(commit))
 405                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 406         if (print_sha1_ellipsis()) {
 407                 fprintf(stderr, "%s %s... %s\n", msg,
 408                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
 409         } else {
 410                 fprintf(stderr, "%s %s %s\n", msg,
 411                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
 412         }
 413         strbuf_release(&sb);
 414 }
 415
 416 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 417                       int worktree, int *writeout_error)
 418 {
 419         struct unpack_trees_options opts;
 420         struct tree_desc tree_desc;
 421
 422         memset(&opts, 0, sizeof(opts));
 423         opts.head_idx = -1;
 424         opts.update = worktree;
 425         opts.skip_unmerged = !worktree;
 426         opts.reset = 1;
 427         opts.merge = 1;
 428         opts.fn = oneway_merge;
 429         opts.verbose_update = o->show_progress;
 430         opts.src_index = &the_index;
 431         opts.dst_index = &the_index;
 432         parse_tree(tree);
 433         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 434         switch (unpack_trees(1, &tree_desc, &opts)) {
 435         case -2:
 436                 *writeout_error = 1;
 437                 /*
 438                  * We return 0 nevertheless, as the index is all right
 439                  * and more importantly we have made best efforts to
 440                  * update paths in the work tree, and we cannot revert
 441                  * them.
 442                  */
 443                 /* fallthrough */
 444         case 0:
 445                 return 0;
 446         default:
 447                 return 128;
 448         }
 449 }
 450
 451 struct branch_info {
 452         const char *name; /* The short name used */
 453         const char *path; /* The full name of a real branch */
 454         struct commit *commit; /* The named commit */
 455         /*
 456          * if not null the branch is detached because it's already
 457          * checked out in this checkout
 458          */
 459         char *checkout;
 460 };
 461
 462 static void setup_branch_path(struct branch_info *branch)
 463 {
 464         struct strbuf buf = STRBUF_INIT;
 465
 466         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 467         if (strcmp(buf.buf, branch->name))
 468                 branch->name = xstrdup(buf.buf);
 469         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 470         branch->path = strbuf_detach(&buf, NULL);
 471 }
 472
 473 static int merge_working_tree(const struct checkout_opts *opts,
 474                               struct branch_info *old,
 475                               struct branch_info *new,
 476                               int *writeout_error)
 477 {
 478         int ret;
 479         struct lock_file lock_file = LOCK_INIT;
 480
 481         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 482         if (read_cache_preload(NULL) < 0)
 483                 return error(_("index file corrupt"));
 484
 485         resolve_undo_clear();
 486         if (opts->force) {
 487                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 488                 if (ret)
 489                         return ret;
 490         } else {
 491                 struct tree_desc trees[2];
 492                 struct tree *tree;
 493                 struct unpack_trees_options topts;
 494
 495                 memset(&topts, 0, sizeof(topts));
 496                 topts.head_idx = -1;
 497                 topts.src_index = &the_index;
 498                 topts.dst_index = &the_index;
 499
 500                 setup_unpack_trees_porcelain(&topts, "checkout");
 501
 502                 refresh_cache(REFRESH_QUIET);
 503
 504                 if (unmerged_cache()) {
 505                         error(_("you need to resolve your current index first"));
 506                         return 1;
 507                 }
 508
 509                 /* 2-way merge to the new branch */
 510                 topts.initial_checkout = is_cache_unborn();
 511                 topts.update = 1;
 512                 topts.merge = 1;
 513                 topts.gently = opts->merge && old->commit;
 514                 topts.verbose_update = opts->show_progress;
 515                 topts.fn = twoway_merge;
 516                 if (opts->overwrite_ignore) {
 517                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 518                         topts.dir->flags |= DIR_SHOW_IGNORED;
 519                         setup_standard_excludes(topts.dir);
 520                 }
 521                 tree = parse_tree_indirect(old->commit ?
 522                                            &old->commit->object.oid :
 523                                            the_hash_algo->empty_tree);
 524                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 525                 tree = parse_tree_indirect(&new->commit->object.oid);
 526                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 527
 528                 ret = unpack_trees(2, trees, &topts);
 529                 if (ret == -1) {
 530                         /*
 531                          * Unpack couldn't do a trivial merge; either
 532                          * give up or do a real merge, depending on
 533                          * whether the merge flag was used.
 534                          */
 535                         struct tree *result;
 536                         struct tree *work;
 537                         struct merge_options o;
 538                         if (!opts->merge)
 539                                 return 1;
 540
 541                         /*
 542                          * Without old->commit, the below is the same as
 543                          * the two-tree unpack we already tried and failed.
 544                          */
 545                         if (!old->commit)
 546                                 return 1;
 547
 548                         /* Do more real merge */
 549
 550                         /*
 551                          * We update the index fully, then write the
 552                          * tree from the index, then merge the new
 553                          * branch with the current tree, with the old
 554                          * branch as the base. Then we reset the index
 555                          * (but not the working tree) to the new
 556                          * branch, leaving the working tree as the
 557                          * merged version, but skipping unmerged
 558                          * entries in the index.
 559                          */
 560
 561                         add_files_to_cache(NULL, NULL, 0);
 562                         /*
 563                          * NEEDSWORK: carrying over local changes
 564                          * when branches have different end-of-line
 565                          * normalization (or clean+smudge rules) is
 566                          * a pain; plumb in an option to set
 567                          * o.renormalize?
 568                          */
 569                         init_merge_options(&o);
 570                         o.verbosity = 0;
 571                         work = write_tree_from_memory(&o);
 572
 573                         ret = reset_tree(new->commit->tree, opts, 1,
 574                                          writeout_error);
 575                         if (ret)
 576                                 return ret;
 577                         o.ancestor = old->name;
 578                         o.branch1 = new->name;
 579                         o.branch2 = "local";
 580                         ret = merge_trees(&o, new->commit->tree, work,
 581                                 old->commit->tree, &result);
 582                         if (ret < 0)
 583                                 exit(128);
 584                         ret = reset_tree(new->commit->tree, opts, 0,
 585                                          writeout_error);
 586                         strbuf_release(&o.obuf);
 587                         if (ret)
 588                                 return ret;
 589                 }
 590         }
 591
 592         if (!active_cache_tree)
 593                 active_cache_tree = cache_tree();
 594
 595         if (!cache_tree_fully_valid(active_cache_tree))
 596                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 597
 598         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 599                 die(_("unable to write new index file"));
 600
 601         if (!opts->force && !opts->quiet)
 602                 show_local_changes(&new->commit->object, &opts->diff_options);
 603
 604         return 0;
 605 }
 606
 607 static void report_tracking(struct branch_info *new)
 608 {
 609         struct strbuf sb = STRBUF_INIT;
 610         struct branch *branch = branch_get(new->name);
 611
 612         if (!format_tracking_info(branch, &sb))
 613                 return;
 614         fputs(sb.buf, stdout);
 615         strbuf_release(&sb);
 616 }
 617
 618 static void update_refs_for_switch(const struct checkout_opts *opts,
 619                                    struct branch_info *old,
 620                                    struct branch_info *new)
 621 {
 622         struct strbuf msg = STRBUF_INIT;
 623         const char *old_desc, *reflog_msg;
 624         if (opts->new_branch) {
 625                 if (opts->new_orphan_branch) {
 626                         char *refname;
 627
 628                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 629                         if (opts->new_branch_log &&
 630                             !should_autocreate_reflog(refname)) {
 631                                 int ret;
 632                                 struct strbuf err = STRBUF_INIT;
 633
 634                                 ret = safe_create_reflog(refname, 1, &err);
 635                                 if (ret) {
 636                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 637                                                 opts->new_orphan_branch, err.buf);
 638                                         strbuf_release(&err);
 639                                         free(refname);
 640                                         return;
 641                                 }
 642                                 strbuf_release(&err);
 643                         }
 644                         free(refname);
 645                 }
 646                 else
 647                         create_branch(opts->new_branch, new->name,
 648                                       opts->new_branch_force ? 1 : 0,
 649                                       opts->new_branch_force ? 1 : 0,
 650                                       opts->new_branch_log,
 651                                       opts->quiet,
 652                                       opts->track);
 653                 new->name = opts->new_branch;
 654                 setup_branch_path(new);
 655         }
 656
 657         old_desc = old->name;
 658         if (!old_desc && old->commit)
 659                 old_desc = oid_to_hex(&old->commit->object.oid);
 660
 661         reflog_msg = getenv("GIT_REFLOG_ACTION");
 662         if (!reflog_msg)
 663                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 664                         old_desc ? old_desc : "(invalid)", new->name);
 665         else
 666                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 667
 668         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 669                 /* Nothing to do. */
 670         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 671                 update_ref(msg.buf, "HEAD", &new->commit->object.oid, NULL,
 672                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 673                 if (!opts->quiet) {
 674                         if (old->path &&
 675                             advice_detached_head && !opts->force_detach)
 676                                 detach_advice(new->name);
 677                         describe_detached_head(_("HEAD is now at"), new->commit);
 678                 }
 679         } else if (new->path) { /* Switch branches. */
 680                 if (create_symref("HEAD", new->path, msg.buf) < 0)
 681                         die(_("unable to update HEAD"));
 682                 if (!opts->quiet) {
 683                         if (old->path && !strcmp(new->path, old->path)) {
 684                                 if (opts->new_branch_force)
 685                                         fprintf(stderr, _("Reset branch '%s'\n"),
 686                                                 new->name);
 687                                 else
 688                                         fprintf(stderr, _("Already on '%s'\n"),
 689                                                 new->name);
 690                         } else if (opts->new_branch) {
 691                                 if (opts->branch_exists)
 692                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 693                                 else
 694                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 695                         } else {
 696                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 697                                         new->name);
 698                         }
 699                 }
 700                 if (old->path && old->name) {
 701                         if (!ref_exists(old->path) && reflog_exists(old->path))
 702                                 delete_reflog(old->path);
 703                 }
 704         }
 705         remove_branch_state();
 706         strbuf_release(&msg);
 707         if (!opts->quiet &&
 708             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 709                 report_tracking(new);
 710 }
 711
 712 static int add_pending_uninteresting_ref(const char *refname,
 713                                          const struct object_id *oid,
 714                                          int flags, void *cb_data)
 715 {
 716         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 717         return 0;
 718 }
 719
 720 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 721 {
 722         strbuf_addstr(sb, "  ");
 723         strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
 724         strbuf_addch(sb, ' ');
 725         if (!parse_commit(commit))
 726                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 727         strbuf_addch(sb, '\n');
 728 }
 729
 730 #define ORPHAN_CUTOFF 4
 731 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 732 {
 733         struct commit *c, *last = NULL;
 734         struct strbuf sb = STRBUF_INIT;
 735         int lost = 0;
 736         while ((c = get_revision(revs)) != NULL) {
 737                 if (lost < ORPHAN_CUTOFF)
 738                         describe_one_orphan(&sb, c);
 739                 last = c;
 740                 lost++;
 741         }
 742         if (ORPHAN_CUTOFF < lost) {
 743                 int more = lost - ORPHAN_CUTOFF;
 744                 if (more == 1)
 745                         describe_one_orphan(&sb, last);
 746                 else
 747                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 748         }
 749
 750         fprintf(stderr,
 751                 Q_(
 752                 /* The singular version */
 753                 "Warning: you are leaving %d commit behind, "
 754                 "not connected to\n"
 755                 "any of your branches:\n\n"
 756                 "%s\n",
 757                 /* The plural version */
 758                 "Warning: you are leaving %d commits behind, "
 759                 "not connected to\n"
 760                 "any of your branches:\n\n"
 761                 "%s\n",
 762                 /* Give ngettext() the count */
 763                 lost),
 764                 lost,
 765                 sb.buf);
 766         strbuf_release(&sb);
 767
 768         if (advice_detached_head)
 769                 fprintf(stderr,
 770                         Q_(
 771                         /* The singular version */
 772                         "If you want to keep it by creating a new branch, "
 773                         "this may be a good time\nto do so with:\n\n"
 774                         " git branch <new-branch-name> %s\n\n",
 775                         /* The plural version */
 776                         "If you want to keep them by creating a new branch, "
 777                         "this may be a good time\nto do so with:\n\n"
 778                         " git branch <new-branch-name> %s\n\n",
 779                         /* Give ngettext() the count */
 780                         lost),
 781                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
 782 }
 783
 784 /*
 785  * We are about to leave commit that was at the tip of a detached
 786  * HEAD.  If it is not reachable from any ref, this is the last chance
 787  * for the user to do so without resorting to reflog.
 788  */
 789 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 790 {
 791         struct rev_info revs;
 792         struct object *object = &old->object;
 793
 794         init_revisions(&revs, NULL);
 795         setup_revisions(0, NULL, &revs, NULL);
 796
 797         object->flags &= ~UNINTERESTING;
 798         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 799
 800         for_each_ref(add_pending_uninteresting_ref, &revs);
 801         add_pending_oid(&revs, "HEAD", &new->object.oid, UNINTERESTING);
 802
 803         if (prepare_revision_walk(&revs))
 804                 die(_("internal error in revision walk"));
 805         if (!(old->object.flags & UNINTERESTING))
 806                 suggest_reattach(old, &revs);
 807         else
 808                 describe_detached_head(_("Previous HEAD position was"), old);
 809
 810         /* Clean up objects used, as they will be reused. */
 811         clear_commit_marks_all(ALL_REV_FLAGS);
 812 }
 813
 814 static int switch_branches(const struct checkout_opts *opts,
 815                            struct branch_info *new)
 816 {
 817         int ret = 0;
 818         struct branch_info old;
 819         void *path_to_free;
 820         struct object_id rev;
 821         int flag, writeout_error = 0;
 822         memset(&old, 0, sizeof(old));
 823         old.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 824         if (old.path)
 825                 old.commit = lookup_commit_reference_gently(&rev, 1);
 826         if (!(flag & REF_ISSYMREF))
 827                 old.path = NULL;
 828
 829         if (old.path)
 830                 skip_prefix(old.path, "refs/heads/", &old.name);
 831
 832         if (!new->name) {
 833                 new->name = "HEAD";
 834                 new->commit = old.commit;
 835                 if (!new->commit)
 836                         die(_("You are on a branch yet to be born"));
 837                 parse_commit_or_die(new->commit);
 838         }
 839
 840         ret = merge_working_tree(opts, &old, new, &writeout_error);
 841         if (ret) {
 842                 free(path_to_free);
 843                 return ret;
 844         }
 845
 846         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 847                 orphaned_commit_warning(old.commit, new->commit);
 848
 849         update_refs_for_switch(opts, &old, new);
 850
 851         ret = post_checkout_hook(old.commit, new->commit, 1);
 852         free(path_to_free);
 853         return ret || writeout_error;
 854 }
 855
 856 static int git_checkout_config(const char *var, const char *value, void *cb)
 857 {
 858         if (!strcmp(var, "diff.ignoresubmodules")) {
 859                 struct checkout_opts *opts = cb;
 860                 handle_ignore_submodules_arg(&opts->diff_options, value);
 861                 return 0;
 862         }
 863
 864         if (starts_with(var, "submodule."))
 865                 return git_default_submodule_config(var, value, NULL);
 866
 867         return git_xmerge_config(var, value, NULL);
 868 }
 869
 870 static int parse_branchname_arg(int argc, const char **argv,
 871                                 int dwim_new_local_branch_ok,
 872                                 struct branch_info *new,
 873                                 struct checkout_opts *opts,
 874                                 struct object_id *rev)
 875 {
 876         struct tree **source_tree = &opts->source_tree;
 877         const char **new_branch = &opts->new_branch;
 878         int argcount = 0;
 879         struct object_id branch_rev;
 880         const char *arg;
 881         int dash_dash_pos;
 882         int has_dash_dash = 0;
 883         int i;
 884
 885         /*
 886          * case 1: git checkout <ref> -- [<paths>]
 887          *
 888          *   <ref> must be a valid tree, everything after the '--' must be
 889          *   a path.
 890          *
 891          * case 2: git checkout -- [<paths>]
 892          *
 893          *   everything after the '--' must be paths.
 894          *
 895          * case 3: git checkout <something> [--]
 896          *
 897          *   (a) If <something> is a commit, that is to
 898          *       switch to the branch or detach HEAD at it.  As a special case,
 899          *       if <something> is A...B (missing A or B means HEAD but you can
 900          *       omit at most one side), and if there is a unique merge base
 901          *       between A and B, A...B names that merge base.
 902          *
 903          *   (b) If <something> is _not_ a commit, either "--" is present
 904          *       or <something> is not a path, no -t or -b was given, and
 905          *       and there is a tracking branch whose name is <something>
 906          *       in one and only one remote, then this is a short-hand to
 907          *       fork local <something> from that remote-tracking branch.
 908          *
 909          *   (c) Otherwise, if "--" is present, treat it like case (1).
 910          *
 911          *   (d) Otherwise :
 912          *       - if it's a reference, treat it like case (1)
 913          *       - else if it's a path, treat it like case (2)
 914          *       - else: fail.
 915          *
 916          * case 4: git checkout <something> <paths>
 917          *
 918          *   The first argument must not be ambiguous.
 919          *   - If it's *only* a reference, treat it like case (1).
 920          *   - If it's only a path, treat it like case (2).
 921          *   - else: fail.
 922          *
 923          */
 924         if (!argc)
 925                 return 0;
 926
 927         arg = argv[0];
 928         dash_dash_pos = -1;
 929         for (i = 0; i < argc; i++) {
 930                 if (!strcmp(argv[i], "--")) {
 931                         dash_dash_pos = i;
 932                         break;
 933                 }
 934         }
 935         if (dash_dash_pos == 0)
 936                 return 1; /* case (2) */
 937         else if (dash_dash_pos == 1)
 938                 has_dash_dash = 1; /* case (3) or (1) */
 939         else if (dash_dash_pos >= 2)
 940                 die(_("only one reference expected, %d given."), dash_dash_pos);
 941
 942         if (!strcmp(arg, "-"))
 943                 arg = "@{-1}";
 944
 945         if (get_oid_mb(arg, rev)) {
 946                 /*
 947                  * Either case (3) or (4), with <something> not being
 948                  * a commit, or an attempt to use case (1) with an
 949                  * invalid ref.
 950                  *
 951                  * It's likely an error, but we need to find out if
 952                  * we should auto-create the branch, case (3).(b).
 953                  */
 954                 int recover_with_dwim = dwim_new_local_branch_ok;
 955
 956                 if (!has_dash_dash &&
 957                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
 958                         recover_with_dwim = 0;
 959                 /*
 960                  * Accept "git checkout foo" and "git checkout foo --"
 961                  * as candidates for dwim.
 962                  */
 963                 if (!(argc == 1 && !has_dash_dash) &&
 964                     !(argc == 2 && has_dash_dash))
 965                         recover_with_dwim = 0;
 966
 967                 if (recover_with_dwim) {
 968                         const char *remote = unique_tracking_name(arg, rev);
 969                         if (remote) {
 970                                 *new_branch = arg;
 971                                 arg = remote;
 972                                 /* DWIMmed to create local branch, case (3).(b) */
 973                         } else {
 974                                 recover_with_dwim = 0;
 975                         }
 976                 }
 977
 978                 if (!recover_with_dwim) {
 979                         if (has_dash_dash)
 980                                 die(_("invalid reference: %s"), arg);
 981                         return argcount;
 982                 }
 983         }
 984
 985         /* we can't end up being in (2) anymore, eat the argument */
 986         argcount++;
 987         argv++;
 988         argc--;
 989
 990         new->name = arg;
 991         setup_branch_path(new);
 992
 993         if (!check_refname_format(new->path, 0) &&
 994             !read_ref(new->path, &branch_rev))
 995                 oidcpy(rev, &branch_rev);
 996         else
 997                 new->path = NULL; /* not an existing branch */
 998
 999         new->commit = lookup_commit_reference_gently(rev, 1);
1000         if (!new->commit) {
1001                 /* not a commit */
1002                 *source_tree = parse_tree_indirect(rev);
1003         } else {
1004                 parse_commit_or_die(new->commit);
1005                 *source_tree = new->commit->tree;
1006         }
1007
1008         if (!*source_tree)                   /* case (1): want a tree */
1009                 die(_("reference is not a tree: %s"), arg);
1010         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1011                 /*
1012                  * Do not complain the most common case
1013                  *      git checkout branch
1014                  * even if there happen to be a file called 'branch';
1015                  * it would be extremely annoying.
1016                  */
1017                 if (argc)
1018                         verify_non_filename(opts->prefix, arg);
1019         } else {
1020                 argcount++;
1021                 argv++;
1022                 argc--;
1023         }
1024
1025         return argcount;
1026 }
1027
1028 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1029 {
1030         int status;
1031         struct strbuf branch_ref = STRBUF_INIT;
1032
1033         if (!opts->new_branch)
1034                 die(_("You are on a branch yet to be born"));
1035         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1036         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1037         strbuf_release(&branch_ref);
1038         if (!opts->quiet)
1039                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1040                         opts->new_branch);
1041         return status;
1042 }
1043
1044 static int checkout_branch(struct checkout_opts *opts,
1045                            struct branch_info *new)
1046 {
1047         if (opts->pathspec.nr)
1048                 die(_("paths cannot be used with switching branches"));
1049
1050         if (opts->patch_mode)
1051                 die(_("'%s' cannot be used with switching branches"),
1052                     "--patch");
1053
1054         if (opts->writeout_stage)
1055                 die(_("'%s' cannot be used with switching branches"),
1056                     "--ours/--theirs");
1057
1058         if (opts->force && opts->merge)
1059                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1060
1061         if (opts->force_detach && opts->new_branch)
1062                 die(_("'%s' cannot be used with '%s'"),
1063                     "--detach", "-b/-B/--orphan");
1064
1065         if (opts->new_orphan_branch) {
1066                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1067                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1068         } else if (opts->force_detach) {
1069                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1070                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1071         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1072                 opts->track = git_branch_track;
1073
1074         if (new->name && !new->commit)
1075                 die(_("Cannot switch branch to a non-commit '%s'"),
1076                     new->name);
1077
1078         if (new->path && !opts->force_detach && !opts->new_branch &&
1079             !opts->ignore_other_worktrees) {
1080                 int flag;
1081                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1082                 if (head_ref &&
1083                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1084                         die_if_checked_out(new->path, 1);
1085                 free(head_ref);
1086         }
1087
1088         if (!new->commit && opts->new_branch) {
1089                 struct object_id rev;
1090                 int flag;
1091
1092                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1093                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1094                         return switch_unborn_to_new_branch(opts);
1095         }
1096         return switch_branches(opts, new);
1097 }
1098
1099 int cmd_checkout(int argc, const char **argv, const char *prefix)
1100 {
1101         struct checkout_opts opts;
1102         struct branch_info new;
1103         char *conflict_style = NULL;
1104         int dwim_new_local_branch = 1;
1105         struct option options[] = {
1106                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1107                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1108                            N_("create and checkout a new branch")),
1109                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1110                            N_("create/reset and checkout a branch")),
1111                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1112                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1113                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1114                         BRANCH_TRACK_EXPLICIT),
1115                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1116                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1117                             2),
1118                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1119                             3),
1120                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1121                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1122                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1123                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1124                            N_("conflict style (merge or diff3)")),
1125                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1126                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1127                          N_("do not limit pathspecs to sparse entries only")),
1128                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1129                                 N_("second guess 'git checkout <no-such-branch>'")),
1130                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1131                          N_("do not check if another worktree is holding the given ref")),
1132                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1133                             "checkout", "control recursive updating of submodules",
1134                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1135                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1136                 OPT_END(),
1137         };
1138
1139         memset(&opts, 0, sizeof(opts));
1140         memset(&new, 0, sizeof(new));
1141         opts.overwrite_ignore = 1;
1142         opts.prefix = prefix;
1143         opts.show_progress = -1;
1144
1145         git_config(git_checkout_config, &opts);
1146
1147         opts.track = BRANCH_TRACK_UNSPECIFIED;
1148
1149         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1150                              PARSE_OPT_KEEP_DASHDASH);
1151
1152         if (opts.show_progress < 0) {
1153                 if (opts.quiet)
1154                         opts.show_progress = 0;
1155                 else
1156                         opts.show_progress = isatty(2);
1157         }
1158
1159         if (conflict_style) {
1160                 opts.merge = 1; /* implied */
1161                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1162         }
1163
1164         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1165                 die(_("-b, -B and --orphan are mutually exclusive"));
1166
1167         /*
1168          * From here on, new_branch will contain the branch to be checked out,
1169          * and new_branch_force and new_orphan_branch will tell us which one of
1170          * -b/-B/--orphan is being used.
1171          */
1172         if (opts.new_branch_force)
1173                 opts.new_branch = opts.new_branch_force;
1174
1175         if (opts.new_orphan_branch)
1176                 opts.new_branch = opts.new_orphan_branch;
1177
1178         /* --track without -b/-B/--orphan should DWIM */
1179         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1180                 const char *argv0 = argv[0];
1181                 if (!argc || !strcmp(argv0, "--"))
1182                         die (_("--track needs a branch name"));
1183                 skip_prefix(argv0, "refs/", &argv0);
1184                 skip_prefix(argv0, "remotes/", &argv0);
1185                 argv0 = strchr(argv0, '/');
1186                 if (!argv0 || !argv0[1])
1187                         die (_("Missing branch name; try -b"));
1188                 opts.new_branch = argv0 + 1;
1189         }
1190
1191         /*
1192          * Extract branch name from command line arguments, so
1193          * all that is left is pathspecs.
1194          *
1195          * Handle
1196          *
1197          *  1) git checkout <tree> -- [<paths>]
1198          *  2) git checkout -- [<paths>]
1199          *  3) git checkout <something> [<paths>]
1200          *
1201          * including "last branch" syntax and DWIM-ery for names of
1202          * remote branches, erroring out for invalid or ambiguous cases.
1203          */
1204         if (argc) {
1205                 struct object_id rev;
1206                 int dwim_ok =
1207                         !opts.patch_mode &&
1208                         dwim_new_local_branch &&
1209                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1210                         !opts.new_branch;
1211                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1212                                              &new, &opts, &rev);
1213                 argv += n;
1214                 argc -= n;
1215         }
1216
1217         if (argc) {
1218                 parse_pathspec(&opts.pathspec, 0,
1219                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1220                                prefix, argv);
1221
1222                 if (!opts.pathspec.nr)
1223                         die(_("invalid path specification"));
1224
1225                 /*
1226                  * Try to give more helpful suggestion.
1227                  * new_branch && argc > 1 will be caught later.
1228                  */
1229                 if (opts.new_branch && argc == 1)
1230                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1231                                 argv[0], opts.new_branch);
1232
1233                 if (opts.force_detach)
1234                         die(_("git checkout: --detach does not take a path argument '%s'"),
1235                             argv[0]);
1236
1237                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1238                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1239                               "checking out of the index."));
1240         }
1241
1242         if (opts.new_branch) {
1243                 struct strbuf buf = STRBUF_INIT;
1244
1245                 if (opts.new_branch_force)
1246                         opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1247                 else
1248                         opts.branch_exists =
1249                                 validate_new_branchname(opts.new_branch, &buf, 0);
1250                 strbuf_release(&buf);
1251         }
1252
1253         UNLEAK(opts);
1254         if (opts.patch_mode || opts.pathspec.nr)
1255                 return checkout_paths(&opts, new.name);
1256         else
1257                 return checkout_branch(&opts, &new);
1258 }