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         resolve_ref("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, opts->track);
 547                 new->name = opts->new_branch;
 548                 setup_branch_path(new);
 549         }
 550
 551         old_desc = old->name;
 552         if (!old_desc && old->commit)
 553                 old_desc = sha1_to_hex(old->commit->object.sha1);
 554         strbuf_addf(&msg, "checkout: moving from %s to %s",
 555                     old_desc ? old_desc : "(invalid)", new->name);
 556
 557         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 558                 /* Nothing to do. */
 559         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 560                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 561                            REF_NODEREF, DIE_ON_ERR);
 562                 if (!opts->quiet) {
 563                         if (old->path && advice_detached_head)
 564                                 detach_advice(old->path, new->name);
 565                         describe_detached_head(_("HEAD is now at"), new->commit);
 566                 }
 567         } else if (new->path) { /* Switch branches. */
 568                 create_symref("HEAD", new->path, msg.buf);
 569                 if (!opts->quiet) {
 570                         if (old->path && !strcmp(new->path, old->path)) {
 571                                 fprintf(stderr, _("Already on '%s'\n"),
 572                                         new->name);
 573                         } else if (opts->new_branch) {
 574                                 if (opts->branch_exists)
 575                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 576                                 else
 577                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 578                         } else {
 579                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 580                                         new->name);
 581                         }
 582                 }
 583                 if (old->path && old->name) {
 584                         char log_file[PATH_MAX], ref_file[PATH_MAX];
 585
 586                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
 587                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
 588                         if (!file_exists(ref_file) && file_exists(log_file))
 589                                 remove_path(log_file);
 590                 }
 591         }
 592         remove_branch_state();
 593         strbuf_release(&msg);
 594         if (!opts->quiet &&
 595             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 596                 report_tracking(new);
 597 }
 598
 599 static int add_pending_uninteresting_ref(const char *refname,
 600                                          const unsigned char *sha1,
 601                                          int flags, void *cb_data)
 602 {
 603         add_pending_sha1(cb_data, refname, sha1, flags | UNINTERESTING);
 604         return 0;
 605 }
 606
 607 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 608 {
 609         parse_commit(commit);
 610         strbuf_addstr(sb, "  ");
 611         strbuf_addstr(sb,
 612                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 613         strbuf_addch(sb, ' ');
 614         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 615         strbuf_addch(sb, '\n');
 616 }
 617
 618 #define ORPHAN_CUTOFF 4
 619 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 620 {
 621         struct commit *c, *last = NULL;
 622         struct strbuf sb = STRBUF_INIT;
 623         int lost = 0;
 624         while ((c = get_revision(revs)) != NULL) {
 625                 if (lost < ORPHAN_CUTOFF)
 626                         describe_one_orphan(&sb, c);
 627                 last = c;
 628                 lost++;
 629         }
 630         if (ORPHAN_CUTOFF < lost) {
 631                 int more = lost - ORPHAN_CUTOFF;
 632                 if (more == 1)
 633                         describe_one_orphan(&sb, last);
 634                 else
 635                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 636         }
 637
 638         fprintf(stderr,
 639                 Q_(
 640                 /* The singular version */
 641                 "Warning: you are leaving %d commit behind, "
 642                 "not connected to\n"
 643                 "any of your branches:\n\n"
 644                 "%s\n",
 645                 /* The plural version */
 646                 "Warning: you are leaving %d commits behind, "
 647                 "not connected to\n"
 648                 "any of your branches:\n\n"
 649                 "%s\n",
 650                 /* Give ngettext() the count */
 651                 lost),
 652                 lost,
 653                 sb.buf);
 654         strbuf_release(&sb);
 655
 656         if (advice_detached_head)
 657                 fprintf(stderr,
 658                         _(
 659                         "If you want to keep them by creating a new branch, "
 660                         "this may be a good time\nto do so with:\n\n"
 661                         " git branch new_branch_name %s\n\n"),
 662                         sha1_to_hex(commit->object.sha1));
 663 }
 664
 665 /*
 666  * We are about to leave commit that was at the tip of a detached
 667  * HEAD.  If it is not reachable from any ref, this is the last chance
 668  * for the user to do so without resorting to reflog.
 669  */
 670 static void orphaned_commit_warning(struct commit *commit)
 671 {
 672         struct rev_info revs;
 673         struct object *object = &commit->object;
 674         struct object_array refs;
 675
 676         init_revisions(&revs, NULL);
 677         setup_revisions(0, NULL, &revs, NULL);
 678
 679         object->flags &= ~UNINTERESTING;
 680         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 681
 682         for_each_ref(add_pending_uninteresting_ref, &revs);
 683
 684         refs = revs.pending;
 685         revs.leak_pending = 1;
 686
 687         if (prepare_revision_walk(&revs))
 688                 die(_("internal error in revision walk"));
 689         if (!(commit->object.flags & UNINTERESTING))
 690                 suggest_reattach(commit, &revs);
 691         else
 692                 describe_detached_head(_("Previous HEAD position was"), commit);
 693
 694         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 695         free(refs.objects);
 696 }
 697
 698 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 699 {
 700         int ret = 0;
 701         struct branch_info old;
 702         unsigned char rev[20];
 703         int flag;
 704         memset(&old, 0, sizeof(old));
 705         old.path = xstrdup(resolve_ref("HEAD", rev, 0, &flag));
 706         old.commit = lookup_commit_reference_gently(rev, 1);
 707         if (!(flag & REF_ISSYMREF)) {
 708                 free((char *)old.path);
 709                 old.path = NULL;
 710         }
 711
 712         if (old.path && !prefixcmp(old.path, "refs/heads/"))
 713                 old.name = old.path + strlen("refs/heads/");
 714
 715         if (!new->name) {
 716                 new->name = "HEAD";
 717                 new->commit = old.commit;
 718                 if (!new->commit)
 719                         die(_("You are on a branch yet to be born"));
 720                 parse_commit(new->commit);
 721         }
 722
 723         ret = merge_working_tree(opts, &old, new);
 724         if (ret)
 725                 return ret;
 726
 727         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 728                 orphaned_commit_warning(old.commit);
 729
 730         update_refs_for_switch(opts, &old, new);
 731
 732         ret = post_checkout_hook(old.commit, new->commit, 1);
 733         free((char *)old.path);
 734         return ret || opts->writeout_error;
 735 }
 736
 737 static int git_checkout_config(const char *var, const char *value, void *cb)
 738 {
 739         if (!strcmp(var, "diff.ignoresubmodules")) {
 740                 struct checkout_opts *opts = cb;
 741                 handle_ignore_submodules_arg(&opts->diff_options, value);
 742                 return 0;
 743         }
 744
 745         if (!prefixcmp(var, "submodule."))
 746                 return parse_submodule_config_option(var, value);
 747
 748         return git_xmerge_config(var, value, NULL);
 749 }
 750
 751 static int interactive_checkout(const char *revision, const char **pathspec,
 752                                 struct checkout_opts *opts)
 753 {
 754         return run_add_interactive(revision, "--patch=checkout", pathspec);
 755 }
 756
 757 struct tracking_name_data {
 758         const char *name;
 759         char *remote;
 760         int unique;
 761 };
 762
 763 static int check_tracking_name(const char *refname, const unsigned char *sha1,
 764                                int flags, void *cb_data)
 765 {
 766         struct tracking_name_data *cb = cb_data;
 767         const char *slash;
 768
 769         if (prefixcmp(refname, "refs/remotes/"))
 770                 return 0;
 771         slash = strchr(refname + 13, '/');
 772         if (!slash || strcmp(slash + 1, cb->name))
 773                 return 0;
 774         if (cb->remote) {
 775                 cb->unique = 0;
 776                 return 0;
 777         }
 778         cb->remote = xstrdup(refname);
 779         return 0;
 780 }
 781
 782 static const char *unique_tracking_name(const char *name)
 783 {
 784         struct tracking_name_data cb_data = { NULL, NULL, 1 };
 785         cb_data.name = name;
 786         for_each_ref(check_tracking_name, &cb_data);
 787         if (cb_data.unique)
 788                 return cb_data.remote;
 789         free(cb_data.remote);
 790         return NULL;
 791 }
 792
 793 static int parse_branchname_arg(int argc, const char **argv,
 794                                 int dwim_new_local_branch_ok,
 795                                 struct branch_info *new,
 796                                 struct tree **source_tree,
 797                                 unsigned char rev[20],
 798                                 const char **new_branch)
 799 {
 800         int argcount = 0;
 801         unsigned char branch_rev[20];
 802         const char *arg;
 803         int has_dash_dash;
 804
 805         /*
 806          * case 1: git checkout <ref> -- [<paths>]
 807          *
 808          *   <ref> must be a valid tree, everything after the '--' must be
 809          *   a path.
 810          *
 811          * case 2: git checkout -- [<paths>]
 812          *
 813          *   everything after the '--' must be paths.
 814          *
 815          * case 3: git checkout <something> [<paths>]
 816          *
 817          *   With no paths, if <something> is a commit, that is to
 818          *   switch to the branch or detach HEAD at it.  As a special case,
 819          *   if <something> is A...B (missing A or B means HEAD but you can
 820          *   omit at most one side), and if there is a unique merge base
 821          *   between A and B, A...B names that merge base.
 822          *
 823          *   With no paths, if <something> is _not_ a commit, no -t nor -b
 824          *   was given, and there is a tracking branch whose name is
 825          *   <something> in one and only one remote, then this is a short-hand
 826          *   to fork local <something> from that remote-tracking branch.
 827          *
 828          *   Otherwise <something> shall not be ambiguous.
 829          *   - If it's *only* a reference, treat it like case (1).
 830          *   - If it's only a path, treat it like case (2).
 831          *   - else: fail.
 832          *
 833          */
 834         if (!argc)
 835                 return 0;
 836
 837         if (!strcmp(argv[0], "--"))     /* case (2) */
 838                 return 1;
 839
 840         arg = argv[0];
 841         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 842
 843         if (!strcmp(arg, "-"))
 844                 arg = "@{-1}";
 845
 846         if (get_sha1_mb(arg, rev)) {
 847                 if (has_dash_dash)          /* case (1) */
 848                         die(_("invalid reference: %s"), arg);
 849                 if (dwim_new_local_branch_ok &&
 850                     !check_filename(NULL, arg) &&
 851                     argc == 1) {
 852                         const char *remote = unique_tracking_name(arg);
 853                         if (!remote || get_sha1(remote, rev))
 854                                 return argcount;
 855                         *new_branch = arg;
 856                         arg = remote;
 857                         /* DWIMmed to create local branch */
 858                 } else {
 859                         return argcount;
 860                 }
 861         }
 862
 863         /* we can't end up being in (2) anymore, eat the argument */
 864         argcount++;
 865         argv++;
 866         argc--;
 867
 868         new->name = arg;
 869         setup_branch_path(new);
 870
 871         if (!check_refname_format(new->path, 0) &&
 872             resolve_ref(new->path, branch_rev, 1, NULL))
 873                 hashcpy(rev, branch_rev);
 874         else
 875                 new->path = NULL; /* not an existing branch */
 876
 877         new->commit = lookup_commit_reference_gently(rev, 1);
 878         if (!new->commit) {
 879                 /* not a commit */
 880                 *source_tree = parse_tree_indirect(rev);
 881         } else {
 882                 parse_commit(new->commit);
 883                 *source_tree = new->commit->tree;
 884         }
 885
 886         if (!*source_tree)                   /* case (1): want a tree */
 887                 die(_("reference is not a tree: %s"), arg);
 888         if (!has_dash_dash) {/* case (3 -> 1) */
 889                 /*
 890                  * Do not complain the most common case
 891                  *      git checkout branch
 892                  * even if there happen to be a file called 'branch';
 893                  * it would be extremely annoying.
 894                  */
 895                 if (argc)
 896                         verify_non_filename(NULL, arg);
 897         } else {
 898                 argcount++;
 899                 argv++;
 900                 argc--;
 901         }
 902
 903         return argcount;
 904 }
 905
 906 int cmd_checkout(int argc, const char **argv, const char *prefix)
 907 {
 908         struct checkout_opts opts;
 909         unsigned char rev[20];
 910         struct branch_info new;
 911         struct tree *source_tree = NULL;
 912         char *conflict_style = NULL;
 913         int patch_mode = 0;
 914         int dwim_new_local_branch = 1;
 915         struct option options[] = {
 916                 OPT__QUIET(&opts.quiet, "suppress progress reporting"),
 917                 OPT_STRING('b', NULL, &opts.new_branch, "branch",
 918                            "create and checkout a new branch"),
 919                 OPT_STRING('B', NULL, &opts.new_branch_force, "branch",
 920                            "create/reset and checkout a branch"),
 921                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "create reflog for new branch"),
 922                 OPT_BOOLEAN(0, "detach", &opts.force_detach, "detach the HEAD at named commit"),
 923                 OPT_SET_INT('t', "track",  &opts.track, "set upstream info for new branch",
 924                         BRANCH_TRACK_EXPLICIT),
 925                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, "new branch", "new unparented branch"),
 926                 OPT_SET_INT('2', "ours", &opts.writeout_stage, "checkout our version for unmerged files",
 927                             2),
 928                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "checkout their version for unmerged files",
 929                             3),
 930                 OPT__FORCE(&opts.force, "force checkout (throw away local modifications)"),
 931                 OPT_BOOLEAN('m', "merge", &opts.merge, "perform a 3-way merge with the new branch"),
 932                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, "update ignored files (default)"),
 933                 OPT_STRING(0, "conflict", &conflict_style, "style",
 934                            "conflict style (merge or diff3)"),
 935                 OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
 936                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
 937                   "second guess 'git checkout no-such-branch'",
 938                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
 939                 OPT_END(),
 940         };
 941
 942         memset(&opts, 0, sizeof(opts));
 943         memset(&new, 0, sizeof(new));
 944         opts.overwrite_ignore = 1;
 945
 946         gitmodules_config();
 947         git_config(git_checkout_config, &opts);
 948
 949         opts.track = BRANCH_TRACK_UNSPECIFIED;
 950
 951         argc = parse_options(argc, argv, prefix, options, checkout_usage,
 952                              PARSE_OPT_KEEP_DASHDASH);
 953
 954         /* we can assume from now on new_branch = !new_branch_force */
 955         if (opts.new_branch && opts.new_branch_force)
 956                 die(_("-B cannot be used with -b"));
 957
 958         /* copy -B over to -b, so that we can just check the latter */
 959         if (opts.new_branch_force)
 960                 opts.new_branch = opts.new_branch_force;
 961
 962         if (patch_mode && (opts.track > 0 || opts.new_branch
 963                            || opts.new_branch_log || opts.merge || opts.force
 964                            || opts.force_detach))
 965                 die (_("--patch is incompatible with all other options"));
 966
 967         if (opts.force_detach && (opts.new_branch || opts.new_orphan_branch))
 968                 die(_("--detach cannot be used with -b/-B/--orphan"));
 969         if (opts.force_detach && 0 < opts.track)
 970                 die(_("--detach cannot be used with -t"));
 971
 972         /* --track without -b should DWIM */
 973         if (0 < opts.track && !opts.new_branch) {
 974                 const char *argv0 = argv[0];
 975                 if (!argc || !strcmp(argv0, "--"))
 976                         die (_("--track needs a branch name"));
 977                 if (!prefixcmp(argv0, "refs/"))
 978                         argv0 += 5;
 979                 if (!prefixcmp(argv0, "remotes/"))
 980                         argv0 += 8;
 981                 argv0 = strchr(argv0, '/');
 982                 if (!argv0 || !argv0[1])
 983                         die (_("Missing branch name; try -b"));
 984                 opts.new_branch = argv0 + 1;
 985         }
 986
 987         if (opts.new_orphan_branch) {
 988                 if (opts.new_branch)
 989                         die(_("--orphan and -b|-B are mutually exclusive"));
 990                 if (opts.track > 0)
 991                         die(_("--orphan cannot be used with -t"));
 992                 opts.new_branch = opts.new_orphan_branch;
 993         }
 994
 995         if (conflict_style) {
 996                 opts.merge = 1; /* implied */
 997                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
 998         }
 999
1000         if (opts.force && opts.merge)
1001                 die(_("git checkout: -f and -m are incompatible"));
1002
1003         /*
1004          * Extract branch name from command line arguments, so
1005          * all that is left is pathspecs.
1006          *
1007          * Handle
1008          *
1009          *  1) git checkout <tree> -- [<paths>]
1010          *  2) git checkout -- [<paths>]
1011          *  3) git checkout <something> [<paths>]
1012          *
1013          * including "last branch" syntax and DWIM-ery for names of
1014          * remote branches, erroring out for invalid or ambiguous cases.
1015          */
1016         if (argc) {
1017                 int dwim_ok =
1018                         !patch_mode &&
1019                         dwim_new_local_branch &&
1020                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1021                         !opts.new_branch;
1022                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1023                                 &new, &source_tree, rev, &opts.new_branch);
1024                 argv += n;
1025                 argc -= n;
1026         }
1027
1028         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
1029                 opts.track = git_branch_track;
1030
1031         if (argc) {
1032                 const char **pathspec = get_pathspec(prefix, argv);
1033
1034                 if (!pathspec)
1035                         die(_("invalid path specification"));
1036
1037                 if (patch_mode)
1038                         return interactive_checkout(new.name, pathspec, &opts);
1039
1040                 /* Checkout paths */
1041                 if (opts.new_branch) {
1042                         if (argc == 1) {
1043                                 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]);
1044                         } else {
1045                                 die(_("git checkout: updating paths is incompatible with switching branches."));
1046                         }
1047                 }
1048
1049                 if (opts.force_detach)
1050                         die(_("git checkout: --detach does not take a path argument"));
1051
1052                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1053                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index."));
1054
1055                 return checkout_paths(source_tree, pathspec, prefix, &opts);
1056         }
1057
1058         if (patch_mode)
1059                 return interactive_checkout(new.name, NULL, &opts);
1060
1061         if (opts.new_branch) {
1062                 struct strbuf buf = STRBUF_INIT;
1063
1064                 opts.branch_exists = validate_new_branchname(opts.new_branch, &buf,
1065                                                              !!opts.new_branch_force, 0);
1066
1067                 strbuf_release(&buf);
1068         }
1069
1070         if (new.name && !new.commit) {
1071                 die(_("Cannot switch branch to a non-commit."));
1072         }
1073         if (opts.writeout_stage)
1074                 die(_("--ours/--theirs is incompatible with switching branches."));
1075
1076         return switch_branches(&opts, &new);
1077 }