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