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