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

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