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