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