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         for (pos = 0; pos < active_nr; pos++) {
 275                 struct cache_entry *ce = active_cache[pos];
 276                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 277                         continue;
 278                 match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
 279         }
 280
 281         if (report_path_error(ps_matched, opts->pathspec, opts->prefix))
 282                 return 1;
 283
 284         /* "checkout -m path" to recreate conflicted state */
 285         if (opts->merge)
 286                 unmerge_cache(opts->pathspec);
 287
 288         /* Any unmerged paths? */
 289         for (pos = 0; pos < active_nr; pos++) {
 290                 struct cache_entry *ce = active_cache[pos];
 291                 if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 292                         if (!ce_stage(ce))
 293                                 continue;
 294                         if (opts->force) {
 295                                 warning(_("path '%s' is unmerged"), ce->name);
 296                         } else if (stage) {
 297                                 errs |= check_stage(stage, ce, pos);
 298                         } else if (opts->merge) {
 299                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 300                         } else {
 301                                 errs = 1;
 302                                 error(_("path '%s' is unmerged"), ce->name);
 303                         }
 304                         pos = skip_same_name(ce, pos) - 1;
 305                 }
 306         }
 307         if (errs)
 308                 return 1;
 309
 310         /* Now we are committed to check them out */
 311         memset(&state, 0, sizeof(state));
 312         state.force = 1;
 313         state.refresh_cache = 1;
 314         for (pos = 0; pos < active_nr; pos++) {
 315                 struct cache_entry *ce = active_cache[pos];
 316                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 317                         continue;
 318                 if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 319                         if (!ce_stage(ce)) {
 320                                 errs |= checkout_entry(ce, &state, NULL);
 321                                 continue;
 322                         }
 323                         if (stage)
 324                                 errs |= checkout_stage(stage, ce, pos, &state);
 325                         else if (merge)
 326                                 errs |= checkout_merged(pos, &state);
 327                         pos = skip_same_name(ce, pos) - 1;
 328                 }
 329         }
 330
 331         if (write_cache(newfd, active_cache, active_nr) ||
 332             commit_locked_index(lock_file))
 333                 die(_("unable to write new index file"));
 334
 335         read_ref_full("HEAD", rev, 0, &flag);
 336         head = lookup_commit_reference_gently(rev, 1);
 337
 338         errs |= post_checkout_hook(head, head, 0);
 339         return errs;
 340 }
 341
 342 static void show_local_changes(struct object *head,
 343                                const struct diff_options *opts)
 344 {
 345         struct rev_info rev;
 346         /* I think we want full paths, even if we're in a subdirectory. */
 347         init_revisions(&rev, NULL);
 348         rev.diffopt.flags = opts->flags;
 349         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 350         diff_setup_done(&rev.diffopt);
 351         add_pending_object(&rev, head, NULL);
 352         run_diff_index(&rev, 0);
 353 }
 354
 355 static void describe_detached_head(const char *msg, struct commit *commit)
 356 {
 357         struct strbuf sb = STRBUF_INIT;
 358         parse_commit(commit);
 359         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 360         fprintf(stderr, "%s %s... %s\n", msg,
 361                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 362         strbuf_release(&sb);
 363 }
 364
 365 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 366                       int worktree, int *writeout_error)
 367 {
 368         struct unpack_trees_options opts;
 369         struct tree_desc tree_desc;
 370
 371         memset(&opts, 0, sizeof(opts));
 372         opts.head_idx = -1;
 373         opts.update = worktree;
 374         opts.skip_unmerged = !worktree;
 375         opts.reset = 1;
 376         opts.merge = 1;
 377         opts.fn = oneway_merge;
 378         opts.verbose_update = !o->quiet && isatty(2);
 379         opts.src_index = &the_index;
 380         opts.dst_index = &the_index;
 381         parse_tree(tree);
 382         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 383         switch (unpack_trees(1, &tree_desc, &opts)) {
 384         case -2:
 385                 *writeout_error = 1;
 386                 /*
 387                  * We return 0 nevertheless, as the index is all right
 388                  * and more importantly we have made best efforts to
 389                  * update paths in the work tree, and we cannot revert
 390                  * them.
 391                  */
 392         case 0:
 393                 return 0;
 394         default:
 395                 return 128;
 396         }
 397 }
 398
 399 struct branch_info {
 400         const char *name; /* The short name used */
 401         const char *path; /* The full name of a real branch */
 402         struct commit *commit; /* The named commit */
 403 };
 404
 405 static void setup_branch_path(struct branch_info *branch)
 406 {
 407         struct strbuf buf = STRBUF_INIT;
 408
 409         strbuf_branchname(&buf, branch->name);
 410         if (strcmp(buf.buf, branch->name))
 411                 branch->name = xstrdup(buf.buf);
 412         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 413         branch->path = strbuf_detach(&buf, NULL);
 414 }
 415
 416 static int merge_working_tree(const struct checkout_opts *opts,
 417                               struct branch_info *old,
 418                               struct branch_info *new,
 419                               int *writeout_error)
 420 {
 421         int ret;
 422         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 423         int newfd = hold_locked_index(lock_file, 1);
 424
 425         if (read_cache_preload(NULL) < 0)
 426                 return error(_("corrupt index file"));
 427
 428         resolve_undo_clear();
 429         if (opts->force) {
 430                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 431                 if (ret)
 432                         return ret;
 433         } else {
 434                 struct tree_desc trees[2];
 435                 struct tree *tree;
 436                 struct unpack_trees_options topts;
 437
 438                 memset(&topts, 0, sizeof(topts));
 439                 topts.head_idx = -1;
 440                 topts.src_index = &the_index;
 441                 topts.dst_index = &the_index;
 442
 443                 setup_unpack_trees_porcelain(&topts, "checkout");
 444
 445                 refresh_cache(REFRESH_QUIET);
 446
 447                 if (unmerged_cache()) {
 448                         error(_("you need to resolve your current index first"));
 449                         return 1;
 450                 }
 451
 452                 /* 2-way merge to the new branch */
 453                 topts.initial_checkout = is_cache_unborn();
 454                 topts.update = 1;
 455                 topts.merge = 1;
 456                 topts.gently = opts->merge && old->commit;
 457                 topts.verbose_update = !opts->quiet && isatty(2);
 458                 topts.fn = twoway_merge;
 459                 if (opts->overwrite_ignore) {
 460                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 461                         topts.dir->flags |= DIR_SHOW_IGNORED;
 462                         setup_standard_excludes(topts.dir);
 463                 }
 464                 tree = parse_tree_indirect(old->commit ?
 465                                            old->commit->object.sha1 :
 466                                            EMPTY_TREE_SHA1_BIN);
 467                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 468                 tree = parse_tree_indirect(new->commit->object.sha1);
 469                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 470
 471                 ret = unpack_trees(2, trees, &topts);
 472                 if (ret == -1) {
 473                         /*
 474                          * Unpack couldn't do a trivial merge; either
 475                          * give up or do a real merge, depending on
 476                          * whether the merge flag was used.
 477                          */
 478                         struct tree *result;
 479                         struct tree *work;
 480                         struct merge_options o;
 481                         if (!opts->merge)
 482                                 return 1;
 483
 484                         /*
 485                          * Without old->commit, the below is the same as
 486                          * the two-tree unpack we already tried and failed.
 487                          */
 488                         if (!old->commit)
 489                                 return 1;
 490
 491                         /* Do more real merge */
 492
 493                         /*
 494                          * We update the index fully, then write the
 495                          * tree from the index, then merge the new
 496                          * branch with the current tree, with the old
 497                          * branch as the base. Then we reset the index
 498                          * (but not the working tree) to the new
 499                          * branch, leaving the working tree as the
 500                          * merged version, but skipping unmerged
 501                          * entries in the index.
 502                          */
 503
 504                         add_files_to_cache(NULL, NULL, 0);
 505                         /*
 506                          * NEEDSWORK: carrying over local changes
 507                          * when branches have different end-of-line
 508                          * normalization (or clean+smudge rules) is
 509                          * a pain; plumb in an option to set
 510                          * o.renormalize?
 511                          */
 512                         init_merge_options(&o);
 513                         o.verbosity = 0;
 514                         work = write_tree_from_memory(&o);
 515
 516                         ret = reset_tree(new->commit->tree, opts, 1,
 517                                          writeout_error);
 518                         if (ret)
 519                                 return ret;
 520                         o.ancestor = old->name;
 521                         o.branch1 = new->name;
 522                         o.branch2 = "local";
 523                         merge_trees(&o, new->commit->tree, work,
 524                                 old->commit->tree, &result);
 525                         ret = reset_tree(new->commit->tree, opts, 0,
 526                                          writeout_error);
 527                         if (ret)
 528                                 return ret;
 529                 }
 530         }
 531
 532         if (write_cache(newfd, active_cache, active_nr) ||
 533             commit_locked_index(lock_file))
 534                 die(_("unable to write new index file"));
 535
 536         if (!opts->force && !opts->quiet)
 537                 show_local_changes(&new->commit->object, &opts->diff_options);
 538
 539         return 0;
 540 }
 541
 542 static void report_tracking(struct branch_info *new)
 543 {
 544         struct strbuf sb = STRBUF_INIT;
 545         struct branch *branch = branch_get(new->name);
 546
 547         if (!format_tracking_info(branch, &sb))
 548                 return;
 549         fputs(sb.buf, stdout);
 550         strbuf_release(&sb);
 551 }
 552
 553 static void update_refs_for_switch(const struct checkout_opts *opts,
 554                                    struct branch_info *old,
 555                                    struct branch_info *new)
 556 {
 557         struct strbuf msg = STRBUF_INIT;
 558         const char *old_desc;
 559         if (opts->new_branch) {
 560                 if (opts->new_orphan_branch) {
 561                         if (opts->new_branch_log && !log_all_ref_updates) {
 562                                 int temp;
 563                                 char log_file[PATH_MAX];
 564                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 565
 566                                 temp = log_all_ref_updates;
 567                                 log_all_ref_updates = 1;
 568                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 569                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 570                                             opts->new_orphan_branch);
 571                                         log_all_ref_updates = temp;
 572                                         return;
 573                                 }
 574                                 log_all_ref_updates = temp;
 575                         }
 576                 }
 577                 else
 578                         create_branch(old->name, opts->new_branch, new->name,
 579                                       opts->new_branch_force ? 1 : 0,
 580                                       opts->new_branch_log,
 581                                       opts->new_branch_force ? 1 : 0,
 582                                       opts->quiet,
 583                                       opts->track);
 584                 new->name = opts->new_branch;
 585                 setup_branch_path(new);
 586         }
 587
 588         old_desc = old->name;
 589         if (!old_desc && old->commit)
 590                 old_desc = sha1_to_hex(old->commit->object.sha1);
 591         strbuf_addf(&msg, "checkout: moving from %s to %s",
 592                     old_desc ? old_desc : "(invalid)", new->name);
 593
 594         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 595                 /* Nothing to do. */
 596         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 597                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 598                            REF_NODEREF, DIE_ON_ERR);
 599                 if (!opts->quiet) {
 600                         if (old->path && advice_detached_head)
 601                                 detach_advice(new->name);
 602                         describe_detached_head(_("HEAD is now at"), new->commit);
 603                 }
 604         } else if (new->path) { /* Switch branches. */
 605                 create_symref("HEAD", new->path, msg.buf);
 606                 if (!opts->quiet) {
 607                         if (old->path && !strcmp(new->path, old->path)) {
 608                                 if (opts->new_branch_force)
 609                                         fprintf(stderr, _("Reset branch '%s'\n"),
 610                                                 new->name);
 611                                 else
 612                                         fprintf(stderr, _("Already on '%s'\n"),
 613                                                 new->name);
 614                         } else if (opts->new_branch) {
 615                                 if (opts->branch_exists)
 616                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 617                                 else
 618                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 619                         } else {
 620                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 621                                         new->name);
 622                         }
 623                 }
 624                 if (old->path && old->name) {
 625                         char log_file[PATH_MAX], ref_file[PATH_MAX];
 626
 627                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
 628                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
 629                         if (!file_exists(ref_file) && file_exists(log_file))
 630                                 remove_path(log_file);
 631                 }
 632         }
 633         remove_branch_state();
 634         strbuf_release(&msg);
 635         if (!opts->quiet &&
 636             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 637                 report_tracking(new);
 638 }
 639
 640 static int add_pending_uninteresting_ref(const char *refname,
 641                                          const unsigned char *sha1,
 642                                          int flags, void *cb_data)
 643 {
 644         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 645         return 0;
 646 }
 647
 648 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 649 {
 650         parse_commit(commit);
 651         strbuf_addstr(sb, "  ");
 652         strbuf_addstr(sb,
 653                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 654         strbuf_addch(sb, ' ');
 655         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 656         strbuf_addch(sb, '\n');
 657 }
 658
 659 #define ORPHAN_CUTOFF 4
 660 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 661 {
 662         struct commit *c, *last = NULL;
 663         struct strbuf sb = STRBUF_INIT;
 664         int lost = 0;
 665         while ((c = get_revision(revs)) != NULL) {
 666                 if (lost < ORPHAN_CUTOFF)
 667                         describe_one_orphan(&sb, c);
 668                 last = c;
 669                 lost++;
 670         }
 671         if (ORPHAN_CUTOFF < lost) {
 672                 int more = lost - ORPHAN_CUTOFF;
 673                 if (more == 1)
 674                         describe_one_orphan(&sb, last);
 675                 else
 676                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 677         }
 678
 679         fprintf(stderr,
 680                 Q_(
 681                 /* The singular version */
 682                 "Warning: you are leaving %d commit behind, "
 683                 "not connected to\n"
 684                 "any of your branches:\n\n"
 685                 "%s\n",
 686                 /* The plural version */
 687                 "Warning: you are leaving %d commits behind, "
 688                 "not connected to\n"
 689                 "any of your branches:\n\n"
 690                 "%s\n",
 691                 /* Give ngettext() the count */
 692                 lost),
 693                 lost,
 694                 sb.buf);
 695         strbuf_release(&sb);
 696
 697         if (advice_detached_head)
 698                 fprintf(stderr,
 699                         _(
 700                         "If you want to keep them by creating a new branch, "
 701                         "this may be a good time\nto do so with:\n\n"
 702                         " git branch new_branch_name %s\n\n"),
 703                         sha1_to_hex(commit->object.sha1));
 704 }
 705
 706 /*
 707  * We are about to leave commit that was at the tip of a detached
 708  * HEAD.  If it is not reachable from any ref, this is the last chance
 709  * for the user to do so without resorting to reflog.
 710  */
 711 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 712 {
 713         struct rev_info revs;
 714         struct object *object = &old->object;
 715         struct object_array refs;
 716
 717         init_revisions(&revs, NULL);
 718         setup_revisions(0, NULL, &revs, NULL);
 719
 720         object->flags &= ~UNINTERESTING;
 721         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 722
 723         for_each_ref(add_pending_uninteresting_ref, &revs);
 724         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 725
 726         refs = revs.pending;
 727         revs.leak_pending = 1;
 728
 729         if (prepare_revision_walk(&revs))
 730                 die(_("internal error in revision walk"));
 731         if (!(old->object.flags & UNINTERESTING))
 732                 suggest_reattach(old, &revs);
 733         else
 734                 describe_detached_head(_("Previous HEAD position was"), old);
 735
 736         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 737         free(refs.objects);
 738 }
 739
 740 static int switch_branches(const struct checkout_opts *opts,
 741                            struct branch_info *new)
 742 {
 743         int ret = 0;
 744         struct branch_info old;
 745         void *path_to_free;
 746         unsigned char rev[20];
 747         int flag, writeout_error = 0;
 748         memset(&old, 0, sizeof(old));
 749         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
 750         old.commit = lookup_commit_reference_gently(rev, 1);
 751         if (!(flag & REF_ISSYMREF))
 752                 old.path = NULL;
 753
 754         if (old.path && !prefixcmp(old.path, "refs/heads/"))
 755                 old.name = old.path + strlen("refs/heads/");
 756
 757         if (!new->name) {
 758                 new->name = "HEAD";
 759                 new->commit = old.commit;
 760                 if (!new->commit)
 761                         die(_("You are on a branch yet to be born"));
 762                 parse_commit(new->commit);
 763         }
 764
 765         ret = merge_working_tree(opts, &old, new, &writeout_error);
 766         if (ret) {
 767                 free(path_to_free);
 768                 return ret;
 769         }
 770
 771         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 772                 orphaned_commit_warning(old.commit, new->commit);
 773
 774         update_refs_for_switch(opts, &old, new);
 775
 776         ret = post_checkout_hook(old.commit, new->commit, 1);
 777         free(path_to_free);
 778         return ret || writeout_error;
 779 }
 780
 781 static int git_checkout_config(const char *var, const char *value, void *cb)
 782 {
 783         if (!strcmp(var, "diff.ignoresubmodules")) {
 784                 struct checkout_opts *opts = cb;
 785                 handle_ignore_submodules_arg(&opts->diff_options, value);
 786                 return 0;
 787         }
 788
 789         if (!prefixcmp(var, "submodule."))
 790                 return parse_submodule_config_option(var, value);
 791
 792         return git_xmerge_config(var, value, NULL);
 793 }
 794
 795 struct tracking_name_data {
 796         const char *name;
 797         char *remote;
 798         int unique;
 799 };
 800
 801 static int check_tracking_name(const char *refname, const unsigned char *sha1,
 802                                int flags, void *cb_data)
 803 {
 804         struct tracking_name_data *cb = cb_data;
 805         const char *slash;
 806
 807         if (prefixcmp(refname, "refs/remotes/"))
 808                 return 0;
 809         slash = strchr(refname + 13, '/');
 810         if (!slash || strcmp(slash + 1, cb->name))
 811                 return 0;
 812         if (cb->remote) {
 813                 cb->unique = 0;
 814                 return 0;
 815         }
 816         cb->remote = xstrdup(refname);
 817         return 0;
 818 }
 819
 820 static const char *unique_tracking_name(const char *name)
 821 {
 822         struct tracking_name_data cb_data = { NULL, NULL, 1 };
 823         cb_data.name = name;
 824         for_each_ref(check_tracking_name, &cb_data);
 825         if (cb_data.unique)
 826                 return cb_data.remote;
 827         free(cb_data.remote);
 828         return NULL;
 829 }
 830
 831 static int parse_branchname_arg(int argc, const char **argv,
 832                                 int dwim_new_local_branch_ok,
 833                                 struct branch_info *new,
 834                                 struct tree **source_tree,
 835                                 unsigned char rev[20],
 836                                 const char **new_branch)
 837 {
 838         int argcount = 0;
 839         unsigned char branch_rev[20];
 840         const char *arg;
 841         int has_dash_dash;
 842
 843         /*
 844          * case 1: git checkout <ref> -- [<paths>]
 845          *
 846          *   <ref> must be a valid tree, everything after the '--' must be
 847          *   a path.
 848          *
 849          * case 2: git checkout -- [<paths>]
 850          *
 851          *   everything after the '--' must be paths.
 852          *
 853          * case 3: git checkout <something> [<paths>]
 854          *
 855          *   With no paths, if <something> is a commit, that is to
 856          *   switch to the branch or detach HEAD at it.  As a special case,
 857          *   if <something> is A...B (missing A or B means HEAD but you can
 858          *   omit at most one side), and if there is a unique merge base
 859          *   between A and B, A...B names that merge base.
 860          *
 861          *   With no paths, if <something> is _not_ a commit, no -t nor -b
 862          *   was given, and there is a tracking branch whose name is
 863          *   <something> in one and only one remote, then this is a short-hand
 864          *   to fork local <something> from that remote-tracking branch.
 865          *
 866          *   Otherwise <something> shall not be ambiguous.
 867          *   - If it's *only* a reference, treat it like case (1).
 868          *   - If it's only a path, treat it like case (2).
 869          *   - else: fail.
 870          *
 871          */
 872         if (!argc)
 873                 return 0;
 874
 875         if (!strcmp(argv[0], "--"))     /* case (2) */
 876                 return 1;
 877
 878         arg = argv[0];
 879         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 880
 881         if (!strcmp(arg, "-"))
 882                 arg = "@{-1}";
 883
 884         if (get_sha1_mb(arg, rev)) {
 885                 if (has_dash_dash)          /* case (1) */
 886                         die(_("invalid reference: %s"), arg);
 887                 if (dwim_new_local_branch_ok &&
 888                     !check_filename(NULL, arg) &&
 889                     argc == 1) {
 890                         const char *remote = unique_tracking_name(arg);
 891                         if (!remote || get_sha1(remote, rev))
 892                                 return argcount;
 893                         *new_branch = arg;
 894                         arg = remote;
 895                         /* DWIMmed to create local branch */
 896                 } else {
 897                         return argcount;
 898                 }
 899         }
 900
 901         /* we can't end up being in (2) anymore, eat the argument */
 902         argcount++;
 903         argv++;
 904         argc--;
 905
 906         new->name = arg;
 907         setup_branch_path(new);
 908
 909         if (!check_refname_format(new->path, 0) &&
 910             !read_ref(new->path, branch_rev))
 911                 hashcpy(rev, branch_rev);
 912         else
 913                 new->path = NULL; /* not an existing branch */
 914
 915         new->commit = lookup_commit_reference_gently(rev, 1);
 916         if (!new->commit) {
 917                 /* not a commit */
 918                 *source_tree = parse_tree_indirect(rev);
 919         } else {
 920                 parse_commit(new->commit);
 921                 *source_tree = new->commit->tree;
 922         }
 923
 924         if (!*source_tree)                   /* case (1): want a tree */
 925                 die(_("reference is not a tree: %s"), arg);
 926         if (!has_dash_dash) {/* case (3 -> 1) */
 927                 /*
 928                  * Do not complain the most common case
 929                  *      git checkout branch
 930                  * even if there happen to be a file called 'branch';
 931                  * it would be extremely annoying.
 932                  */
 933                 if (argc)
 934                         verify_non_filename(NULL, arg);
 935         } else {
 936                 argcount++;
 937                 argv++;
 938                 argc--;
 939         }
 940
 941         return argcount;
 942 }
 943
 944 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
 945 {
 946         int status;
 947         struct strbuf branch_ref = STRBUF_INIT;
 948
 949         if (!opts->new_branch)
 950                 die(_("You are on a branch yet to be born"));
 951         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
 952         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
 953         strbuf_release(&branch_ref);
 954         if (!opts->quiet)
 955                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
 956                         opts->new_branch);
 957         return status;
 958 }
 959
 960 static int checkout_branch(struct checkout_opts *opts,
 961                            struct branch_info *new)
 962 {
 963         if (opts->pathspec)
 964                 die(_("paths cannot be used with switching branches"));
 965
 966         if (opts->patch_mode)
 967                 die(_("'%s' cannot be used with switching branches"),
 968                     "--patch");
 969
 970         if (opts->writeout_stage)
 971                 die(_("'%s' cannot be used with switching branches"),
 972                     "--ours/--theirs");
 973
 974         if (opts->force && opts->merge)
 975                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
 976
 977         if (opts->force_detach && opts->new_branch)
 978                 die(_("'%s' cannot be used with '%s'"),
 979                     "--detach", "-b/-B/--orphan");
 980
 981         if (opts->new_orphan_branch) {
 982                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 983                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
 984         } else if (opts->force_detach) {
 985                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 986                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
 987         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
 988                 opts->track = git_branch_track;
 989
 990         if (new->name && !new->commit)
 991                 die(_("Cannot switch branch to a non-commit '%s'"),
 992                     new->name);
 993
 994         if (!new->commit && opts->new_branch) {
 995                 unsigned char rev[20];
 996                 int flag;
 997
 998                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
 999                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1000                         return switch_unborn_to_new_branch(opts);
1001         }
1002         return switch_branches(opts, new);
1003 }
1004
1005 int cmd_checkout(int argc, const char **argv, const char *prefix)
1006 {
1007         struct checkout_opts opts;
1008         struct branch_info new;
1009         char *conflict_style = NULL;
1010         int dwim_new_local_branch = 1;
1011         struct option options[] = {
1012                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1013                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1014                            N_("create and checkout a new branch")),
1015                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1016                            N_("create/reset and checkout a branch")),
1017                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1018                 OPT_BOOLEAN(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1019                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1020                         BRANCH_TRACK_EXPLICIT),
1021                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new branch"), N_("new unparented branch")),
1022                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1023                             2),
1024                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1025                             3),
1026                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1027                 OPT_BOOLEAN('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1028                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1029                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1030                            N_("conflict style (merge or diff3)")),
1031                 OPT_BOOLEAN('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1032                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
1033                   N_("second guess 'git checkout no-such-branch'"),
1034                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
1035                 OPT_END(),
1036         };
1037
1038         memset(&opts, 0, sizeof(opts));
1039         memset(&new, 0, sizeof(new));
1040         opts.overwrite_ignore = 1;
1041         opts.prefix = prefix;
1042
1043         gitmodules_config();
1044         git_config(git_checkout_config, &opts);
1045
1046         opts.track = BRANCH_TRACK_UNSPECIFIED;
1047
1048         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1049                              PARSE_OPT_KEEP_DASHDASH);
1050
1051         if (conflict_style) {
1052                 opts.merge = 1; /* implied */
1053                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1054         }
1055
1056         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1057                 die(_("-b, -B and --orphan are mutually exclusive"));
1058
1059         /*
1060          * From here on, new_branch will contain the branch to be checked out,
1061          * and new_branch_force and new_orphan_branch will tell us which one of
1062          * -b/-B/--orphan is being used.
1063          */
1064         if (opts.new_branch_force)
1065                 opts.new_branch = opts.new_branch_force;
1066
1067         if (opts.new_orphan_branch)
1068                 opts.new_branch = opts.new_orphan_branch;
1069
1070         /* --track without -b/-B/--orphan should DWIM */
1071         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1072                 const char *argv0 = argv[0];
1073                 if (!argc || !strcmp(argv0, "--"))
1074                         die (_("--track needs a branch name"));
1075                 if (!prefixcmp(argv0, "refs/"))
1076                         argv0 += 5;
1077                 if (!prefixcmp(argv0, "remotes/"))
1078                         argv0 += 8;
1079                 argv0 = strchr(argv0, '/');
1080                 if (!argv0 || !argv0[1])
1081                         die (_("Missing branch name; try -b"));
1082                 opts.new_branch = argv0 + 1;
1083         }
1084
1085         /*
1086          * Extract branch name from command line arguments, so
1087          * all that is left is pathspecs.
1088          *
1089          * Handle
1090          *
1091          *  1) git checkout <tree> -- [<paths>]
1092          *  2) git checkout -- [<paths>]
1093          *  3) git checkout <something> [<paths>]
1094          *
1095          * including "last branch" syntax and DWIM-ery for names of
1096          * remote branches, erroring out for invalid or ambiguous cases.
1097          */
1098         if (argc) {
1099                 unsigned char rev[20];
1100                 int dwim_ok =
1101                         !opts.patch_mode &&
1102                         dwim_new_local_branch &&
1103                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1104                         !opts.new_branch;
1105                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1106                                              &new, &opts.source_tree,
1107                                              rev, &opts.new_branch);
1108                 argv += n;
1109                 argc -= n;
1110         }
1111
1112         if (argc) {
1113                 opts.pathspec = get_pathspec(prefix, argv);
1114
1115                 if (!opts.pathspec)
1116                         die(_("invalid path specification"));
1117
1118                 /*
1119                  * Try to give more helpful suggestion.
1120                  * new_branch && argc > 1 will be caught later.
1121                  */
1122                 if (opts.new_branch && argc == 1)
1123                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1124                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1125                             opts.new_branch, argv[0]);
1126
1127                 if (opts.force_detach)
1128                         die(_("git checkout: --detach does not take a path argument '%s'"),
1129                             argv[0]);
1130
1131                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1132                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1133                               "checking out of the index."));
1134         }
1135
1136         if (opts.new_branch) {
1137                 struct strbuf buf = STRBUF_INIT;
1138
1139                 opts.branch_exists =
1140                         validate_new_branchname(opts.new_branch, &buf,
1141                                                 !!opts.new_branch_force,
1142                                                 !!opts.new_branch_force);
1143
1144                 strbuf_release(&buf);
1145         }
1146
1147         if (opts.patch_mode || opts.pathspec)
1148                 return checkout_paths(&opts, new.name);
1149         else
1150                 return checkout_branch(&opts, &new);
1151 }