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 overwrite_ignore;
  37
  38         /* not set by parse_options */
  39         int branch_exists;
  40
  41         const char *new_branch;
  42         const char *new_branch_force;
  43         const char *new_orphan_branch;
  44         int new_branch_log;
  45         enum branch_track track;
  46         struct diff_options diff_options;
  47 };
  48
  49 static int post_checkout_hook(struct commit *old, struct commit *new,
  50                               int changed)
  51 {
  52         return run_hook(NULL, "post-checkout",
  53                         sha1_to_hex(old ? old->object.sha1 : null_sha1),
  54                         sha1_to_hex(new ? new->object.sha1 : null_sha1),
  55                         changed ? "1" : "0", NULL);
  56         /* "new" can be NULL when checking out from the index before
  57            a commit exists. */
  58
  59 }
  60
  61 static int update_some(const unsigned char *sha1, const char *base, int baselen,
  62                 const char *pathname, unsigned mode, int stage, void *context)
  63 {
  64         int len;
  65         struct cache_entry *ce;
  66
  67         if (S_ISDIR(mode))
  68                 return READ_TREE_RECURSIVE;
  69
  70         len = baselen + strlen(pathname);
  71         ce = xcalloc(1, cache_entry_size(len));
  72         hashcpy(ce->sha1, sha1);
  73         memcpy(ce->name, base, baselen);
  74         memcpy(ce->name + baselen, pathname, len - baselen);
  75         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  76         ce->ce_namelen = len;
  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, const 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,
 312                                const struct diff_options *opts)
 313 {
 314         struct rev_info rev;
 315         /* I think we want full paths, even if we're in a subdirectory. */
 316         init_revisions(&rev, NULL);
 317         rev.diffopt.flags = opts->flags;
 318         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 319         diff_setup_done(&rev.diffopt);
 320         add_pending_object(&rev, head, NULL);
 321         run_diff_index(&rev, 0);
 322 }
 323
 324 static void describe_detached_head(const char *msg, struct commit *commit)
 325 {
 326         struct strbuf sb = STRBUF_INIT;
 327         parse_commit(commit);
 328         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 329         fprintf(stderr, "%s %s... %s\n", msg,
 330                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 331         strbuf_release(&sb);
 332 }
 333
 334 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 335                       int worktree, int *writeout_error)
 336 {
 337         struct unpack_trees_options opts;
 338         struct tree_desc tree_desc;
 339
 340         memset(&opts, 0, sizeof(opts));
 341         opts.head_idx = -1;
 342         opts.update = worktree;
 343         opts.skip_unmerged = !worktree;
 344         opts.reset = 1;
 345         opts.merge = 1;
 346         opts.fn = oneway_merge;
 347         opts.verbose_update = !o->quiet && isatty(2);
 348         opts.src_index = &the_index;
 349         opts.dst_index = &the_index;
 350         parse_tree(tree);
 351         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 352         switch (unpack_trees(1, &tree_desc, &opts)) {
 353         case -2:
 354                 *writeout_error = 1;
 355                 /*
 356                  * We return 0 nevertheless, as the index is all right
 357                  * and more importantly we have made best efforts to
 358                  * update paths in the work tree, and we cannot revert
 359                  * them.
 360                  */
 361         case 0:
 362                 return 0;
 363         default:
 364                 return 128;
 365         }
 366 }
 367
 368 struct branch_info {
 369         const char *name; /* The short name used */
 370         const char *path; /* The full name of a real branch */
 371         struct commit *commit; /* The named commit */
 372 };
 373
 374 static void setup_branch_path(struct branch_info *branch)
 375 {
 376         struct strbuf buf = STRBUF_INIT;
 377
 378         strbuf_branchname(&buf, branch->name);
 379         if (strcmp(buf.buf, branch->name))
 380                 branch->name = xstrdup(buf.buf);
 381         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 382         branch->path = strbuf_detach(&buf, NULL);
 383 }
 384
 385 static int merge_working_tree(const struct checkout_opts *opts,
 386                               struct branch_info *old,
 387                               struct branch_info *new,
 388                               int *writeout_error)
 389 {
 390         int ret;
 391         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 392         int newfd = hold_locked_index(lock_file, 1);
 393
 394         if (read_cache_preload(NULL) < 0)
 395                 return error(_("corrupt index file"));
 396
 397         resolve_undo_clear();
 398         if (opts->force) {
 399                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 400                 if (ret)
 401                         return ret;
 402         } else {
 403                 struct tree_desc trees[2];
 404                 struct tree *tree;
 405                 struct unpack_trees_options topts;
 406
 407                 memset(&topts, 0, sizeof(topts));
 408                 topts.head_idx = -1;
 409                 topts.src_index = &the_index;
 410                 topts.dst_index = &the_index;
 411
 412                 setup_unpack_trees_porcelain(&topts, "checkout");
 413
 414                 refresh_cache(REFRESH_QUIET);
 415
 416                 if (unmerged_cache()) {
 417                         error(_("you need to resolve your current index first"));
 418                         return 1;
 419                 }
 420
 421                 /* 2-way merge to the new branch */
 422                 topts.initial_checkout = is_cache_unborn();
 423                 topts.update = 1;
 424                 topts.merge = 1;
 425                 topts.gently = opts->merge && old->commit;
 426                 topts.verbose_update = !opts->quiet && isatty(2);
 427                 topts.fn = twoway_merge;
 428                 if (opts->overwrite_ignore) {
 429                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 430                         topts.dir->flags |= DIR_SHOW_IGNORED;
 431                         setup_standard_excludes(topts.dir);
 432                 }
 433                 tree = parse_tree_indirect(old->commit ?
 434                                            old->commit->object.sha1 :
 435                                            EMPTY_TREE_SHA1_BIN);
 436                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 437                 tree = parse_tree_indirect(new->commit->object.sha1);
 438                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 439
 440                 ret = unpack_trees(2, trees, &topts);
 441                 if (ret == -1) {
 442                         /*
 443                          * Unpack couldn't do a trivial merge; either
 444                          * give up or do a real merge, depending on
 445                          * whether the merge flag was used.
 446                          */
 447                         struct tree *result;
 448                         struct tree *work;
 449                         struct merge_options o;
 450                         if (!opts->merge)
 451                                 return 1;
 452
 453                         /*
 454                          * Without old->commit, the below is the same as
 455                          * the two-tree unpack we already tried and failed.
 456                          */
 457                         if (!old->commit)
 458                                 return 1;
 459
 460                         /* Do more real merge */
 461
 462                         /*
 463                          * We update the index fully, then write the
 464                          * tree from the index, then merge the new
 465                          * branch with the current tree, with the old
 466                          * branch as the base. Then we reset the index
 467                          * (but not the working tree) to the new
 468                          * branch, leaving the working tree as the
 469                          * merged version, but skipping unmerged
 470                          * entries in the index.
 471                          */
 472
 473                         add_files_to_cache(NULL, NULL, 0);
 474                         /*
 475                          * NEEDSWORK: carrying over local changes
 476                          * when branches have different end-of-line
 477                          * normalization (or clean+smudge rules) is
 478                          * a pain; plumb in an option to set
 479                          * o.renormalize?
 480                          */
 481                         init_merge_options(&o);
 482                         o.verbosity = 0;
 483                         work = write_tree_from_memory(&o);
 484
 485                         ret = reset_tree(new->commit->tree, opts, 1,
 486                                          writeout_error);
 487                         if (ret)
 488                                 return ret;
 489                         o.ancestor = old->name;
 490                         o.branch1 = new->name;
 491                         o.branch2 = "local";
 492                         merge_trees(&o, new->commit->tree, work,
 493                                 old->commit->tree, &result);
 494                         ret = reset_tree(new->commit->tree, opts, 0,
 495                                          writeout_error);
 496                         if (ret)
 497                                 return ret;
 498                 }
 499         }
 500
 501         if (write_cache(newfd, active_cache, active_nr) ||
 502             commit_locked_index(lock_file))
 503                 die(_("unable to write new index file"));
 504
 505         if (!opts->force && !opts->quiet)
 506                 show_local_changes(&new->commit->object, &opts->diff_options);
 507
 508         return 0;
 509 }
 510
 511 static void report_tracking(struct branch_info *new)
 512 {
 513         struct strbuf sb = STRBUF_INIT;
 514         struct branch *branch = branch_get(new->name);
 515
 516         if (!format_tracking_info(branch, &sb))
 517                 return;
 518         fputs(sb.buf, stdout);
 519         strbuf_release(&sb);
 520 }
 521
 522 static void update_refs_for_switch(const struct checkout_opts *opts,
 523                                    struct branch_info *old,
 524                                    struct branch_info *new)
 525 {
 526         struct strbuf msg = STRBUF_INIT;
 527         const char *old_desc;
 528         if (opts->new_branch) {
 529                 if (opts->new_orphan_branch) {
 530                         if (opts->new_branch_log && !log_all_ref_updates) {
 531                                 int temp;
 532                                 char log_file[PATH_MAX];
 533                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 534
 535                                 temp = log_all_ref_updates;
 536                                 log_all_ref_updates = 1;
 537                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 538                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 539                                             opts->new_orphan_branch);
 540                                         log_all_ref_updates = temp;
 541                                         return;
 542                                 }
 543                                 log_all_ref_updates = temp;
 544                         }
 545                 }
 546                 else
 547                         create_branch(old->name, opts->new_branch, new->name,
 548                                       opts->new_branch_force ? 1 : 0,
 549                                       opts->new_branch_log,
 550                                       opts->new_branch_force ? 1 : 0,
 551                                       opts->quiet,
 552                                       opts->track);
 553                 new->name = opts->new_branch;
 554                 setup_branch_path(new);
 555         }
 556
 557         old_desc = old->name;
 558         if (!old_desc && old->commit)
 559                 old_desc = sha1_to_hex(old->commit->object.sha1);
 560         strbuf_addf(&msg, "checkout: moving from %s to %s",
 561                     old_desc ? old_desc : "(invalid)", new->name);
 562
 563         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 564                 /* Nothing to do. */
 565         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 566                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 567                            REF_NODEREF, DIE_ON_ERR);
 568                 if (!opts->quiet) {
 569                         if (old->path && advice_detached_head)
 570                                 detach_advice(new->name);
 571                         describe_detached_head(_("HEAD is now at"), new->commit);
 572                 }
 573         } else if (new->path) { /* Switch branches. */
 574                 create_symref("HEAD", new->path, msg.buf);
 575                 if (!opts->quiet) {
 576                         if (old->path && !strcmp(new->path, old->path)) {
 577                                 if (opts->new_branch_force)
 578                                         fprintf(stderr, _("Reset branch '%s'\n"),
 579                                                 new->name);
 580                                 else
 581                                         fprintf(stderr, _("Already on '%s'\n"),
 582                                                 new->name);
 583                         } else if (opts->new_branch) {
 584                                 if (opts->branch_exists)
 585                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 586                                 else
 587                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 588                         } else {
 589                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 590                                         new->name);
 591                         }
 592                 }
 593                 if (old->path && old->name) {
 594                         char log_file[PATH_MAX], ref_file[PATH_MAX];
 595
 596                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
 597                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
 598                         if (!file_exists(ref_file) && file_exists(log_file))
 599                                 remove_path(log_file);
 600                 }
 601         }
 602         remove_branch_state();
 603         strbuf_release(&msg);
 604         if (!opts->quiet &&
 605             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 606                 report_tracking(new);
 607 }
 608
 609 static int add_pending_uninteresting_ref(const char *refname,
 610                                          const unsigned char *sha1,
 611                                          int flags, void *cb_data)
 612 {
 613         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 614         return 0;
 615 }
 616
 617 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 618 {
 619         parse_commit(commit);
 620         strbuf_addstr(sb, "  ");
 621         strbuf_addstr(sb,
 622                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 623         strbuf_addch(sb, ' ');
 624         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 625         strbuf_addch(sb, '\n');
 626 }
 627
 628 #define ORPHAN_CUTOFF 4
 629 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 630 {
 631         struct commit *c, *last = NULL;
 632         struct strbuf sb = STRBUF_INIT;
 633         int lost = 0;
 634         while ((c = get_revision(revs)) != NULL) {
 635                 if (lost < ORPHAN_CUTOFF)
 636                         describe_one_orphan(&sb, c);
 637                 last = c;
 638                 lost++;
 639         }
 640         if (ORPHAN_CUTOFF < lost) {
 641                 int more = lost - ORPHAN_CUTOFF;
 642                 if (more == 1)
 643                         describe_one_orphan(&sb, last);
 644                 else
 645                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 646         }
 647
 648         fprintf(stderr,
 649                 Q_(
 650                 /* The singular version */
 651                 "Warning: you are leaving %d commit behind, "
 652                 "not connected to\n"
 653                 "any of your branches:\n\n"
 654                 "%s\n",
 655                 /* The plural version */
 656                 "Warning: you are leaving %d commits behind, "
 657                 "not connected to\n"
 658                 "any of your branches:\n\n"
 659                 "%s\n",
 660                 /* Give ngettext() the count */
 661                 lost),
 662                 lost,
 663                 sb.buf);
 664         strbuf_release(&sb);
 665
 666         if (advice_detached_head)
 667                 fprintf(stderr,
 668                         _(
 669                         "If you want to keep them by creating a new branch, "
 670                         "this may be a good time\nto do so with:\n\n"
 671                         " git branch new_branch_name %s\n\n"),
 672                         sha1_to_hex(commit->object.sha1));
 673 }
 674
 675 /*
 676  * We are about to leave commit that was at the tip of a detached
 677  * HEAD.  If it is not reachable from any ref, this is the last chance
 678  * for the user to do so without resorting to reflog.
 679  */
 680 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 681 {
 682         struct rev_info revs;
 683         struct object *object = &old->object;
 684         struct object_array refs;
 685
 686         init_revisions(&revs, NULL);
 687         setup_revisions(0, NULL, &revs, NULL);
 688
 689         object->flags &= ~UNINTERESTING;
 690         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 691
 692         for_each_ref(add_pending_uninteresting_ref, &revs);
 693         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 694
 695         refs = revs.pending;
 696         revs.leak_pending = 1;
 697
 698         if (prepare_revision_walk(&revs))
 699                 die(_("internal error in revision walk"));
 700         if (!(old->object.flags & UNINTERESTING))
 701                 suggest_reattach(old, &revs);
 702         else
 703                 describe_detached_head(_("Previous HEAD position was"), old);
 704
 705         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 706         free(refs.objects);
 707 }
 708
 709 static int switch_branches(const struct checkout_opts *opts, struct branch_info *new)
 710 {
 711         int ret = 0;
 712         struct branch_info old;
 713         void *path_to_free;
 714         unsigned char rev[20];
 715         int flag, writeout_error = 0;
 716         memset(&old, 0, sizeof(old));
 717         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
 718         old.commit = lookup_commit_reference_gently(rev, 1);
 719         if (!(flag & REF_ISSYMREF))
 720                 old.path = NULL;
 721
 722         if (old.path && !prefixcmp(old.path, "refs/heads/"))
 723                 old.name = old.path + strlen("refs/heads/");
 724
 725         if (!new->name) {
 726                 new->name = "HEAD";
 727                 new->commit = old.commit;
 728                 if (!new->commit)
 729                         die(_("You are on a branch yet to be born"));
 730                 parse_commit(new->commit);
 731         }
 732
 733         ret = merge_working_tree(opts, &old, new, &writeout_error);
 734         if (ret) {
 735                 free(path_to_free);
 736                 return ret;
 737         }
 738
 739         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 740                 orphaned_commit_warning(old.commit, new->commit);
 741
 742         update_refs_for_switch(opts, &old, new);
 743
 744         ret = post_checkout_hook(old.commit, new->commit, 1);
 745         free(path_to_free);
 746         return ret || writeout_error;
 747 }
 748
 749 static int git_checkout_config(const char *var, const char *value, void *cb)
 750 {
 751         if (!strcmp(var, "diff.ignoresubmodules")) {
 752                 struct checkout_opts *opts = cb;
 753                 handle_ignore_submodules_arg(&opts->diff_options, value);
 754                 return 0;
 755         }
 756
 757         if (!prefixcmp(var, "submodule."))
 758                 return parse_submodule_config_option(var, value);
 759
 760         return git_xmerge_config(var, value, NULL);
 761 }
 762
 763 static int interactive_checkout(const char *revision, const char **pathspec,
 764                                 struct checkout_opts *opts)
 765 {
 766         return run_add_interactive(revision, "--patch=checkout", pathspec);
 767 }
 768
 769 struct tracking_name_data {
 770         const char *name;
 771         char *remote;
 772         int unique;
 773 };
 774
 775 static int check_tracking_name(const char *refname, const unsigned char *sha1,
 776                                int flags, void *cb_data)
 777 {
 778         struct tracking_name_data *cb = cb_data;
 779         const char *slash;
 780
 781         if (prefixcmp(refname, "refs/remotes/"))
 782                 return 0;
 783         slash = strchr(refname + 13, '/');
 784         if (!slash || strcmp(slash + 1, cb->name))
 785                 return 0;
 786         if (cb->remote) {
 787                 cb->unique = 0;
 788                 return 0;
 789         }
 790         cb->remote = xstrdup(refname);
 791         return 0;
 792 }
 793
 794 static const char *unique_tracking_name(const char *name)
 795 {
 796         struct tracking_name_data cb_data = { NULL, NULL, 1 };
 797         cb_data.name = name;
 798         for_each_ref(check_tracking_name, &cb_data);
 799         if (cb_data.unique)
 800                 return cb_data.remote;
 801         free(cb_data.remote);
 802         return NULL;
 803 }
 804
 805 static int parse_branchname_arg(int argc, const char **argv,
 806                                 int dwim_new_local_branch_ok,
 807                                 struct branch_info *new,
 808                                 struct tree **source_tree,
 809                                 unsigned char rev[20],
 810                                 const char **new_branch)
 811 {
 812         int argcount = 0;
 813         unsigned char branch_rev[20];
 814         const char *arg;
 815         int has_dash_dash;
 816
 817         /*
 818          * case 1: git checkout <ref> -- [<paths>]
 819          *
 820          *   <ref> must be a valid tree, everything after the '--' must be
 821          *   a path.
 822          *
 823          * case 2: git checkout -- [<paths>]
 824          *
 825          *   everything after the '--' must be paths.
 826          *
 827          * case 3: git checkout <something> [<paths>]
 828          *
 829          *   With no paths, if <something> is a commit, that is to
 830          *   switch to the branch or detach HEAD at it.  As a special case,
 831          *   if <something> is A...B (missing A or B means HEAD but you can
 832          *   omit at most one side), and if there is a unique merge base
 833          *   between A and B, A...B names that merge base.
 834          *
 835          *   With no paths, if <something> is _not_ a commit, no -t nor -b
 836          *   was given, and there is a tracking branch whose name is
 837          *   <something> in one and only one remote, then this is a short-hand
 838          *   to fork local <something> from that remote-tracking branch.
 839          *
 840          *   Otherwise <something> shall not be ambiguous.
 841          *   - If it's *only* a reference, treat it like case (1).
 842          *   - If it's only a path, treat it like case (2).
 843          *   - else: fail.
 844          *
 845          */
 846         if (!argc)
 847                 return 0;
 848
 849         if (!strcmp(argv[0], "--"))     /* case (2) */
 850                 return 1;
 851
 852         arg = argv[0];
 853         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 854
 855         if (!strcmp(arg, "-"))
 856                 arg = "@{-1}";
 857
 858         if (get_sha1_mb(arg, rev)) {
 859                 if (has_dash_dash)          /* case (1) */
 860                         die(_("invalid reference: %s"), arg);
 861                 if (dwim_new_local_branch_ok &&
 862                     !check_filename(NULL, arg) &&
 863                     argc == 1) {
 864                         const char *remote = unique_tracking_name(arg);
 865                         if (!remote || get_sha1(remote, rev))
 866                                 return argcount;
 867                         *new_branch = arg;
 868                         arg = remote;
 869                         /* DWIMmed to create local branch */
 870                 } else {
 871                         return argcount;
 872                 }
 873         }
 874
 875         /* we can't end up being in (2) anymore, eat the argument */
 876         argcount++;
 877         argv++;
 878         argc--;
 879
 880         new->name = arg;
 881         setup_branch_path(new);
 882
 883         if (!check_refname_format(new->path, 0) &&
 884             !read_ref(new->path, branch_rev))
 885                 hashcpy(rev, branch_rev);
 886         else
 887                 new->path = NULL; /* not an existing branch */
 888
 889         new->commit = lookup_commit_reference_gently(rev, 1);
 890         if (!new->commit) {
 891                 /* not a commit */
 892                 *source_tree = parse_tree_indirect(rev);
 893         } else {
 894                 parse_commit(new->commit);
 895                 *source_tree = new->commit->tree;
 896         }
 897
 898         if (!*source_tree)                   /* case (1): want a tree */
 899                 die(_("reference is not a tree: %s"), arg);
 900         if (!has_dash_dash) {/* case (3 -> 1) */
 901                 /*
 902                  * Do not complain the most common case
 903                  *      git checkout branch
 904                  * even if there happen to be a file called 'branch';
 905                  * it would be extremely annoying.
 906                  */
 907                 if (argc)
 908                         verify_non_filename(NULL, arg);
 909         } else {
 910                 argcount++;
 911                 argv++;
 912                 argc--;
 913         }
 914
 915         return argcount;
 916 }
 917
 918 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
 919 {
 920         int status;
 921         struct strbuf branch_ref = STRBUF_INIT;
 922
 923         if (!opts->new_branch)
 924                 die(_("You are on a branch yet to be born"));
 925         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
 926         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
 927         strbuf_release(&branch_ref);
 928         return status;
 929 }
 930
 931 int cmd_checkout(int argc, const char **argv, const char *prefix)
 932 {
 933         struct checkout_opts opts;
 934         unsigned char rev[20];
 935         struct branch_info new;
 936         struct tree *source_tree = NULL;
 937         char *conflict_style = NULL;
 938         int patch_mode = 0;
 939         int dwim_new_local_branch = 1;
 940         struct option options[] = {
 941                 OPT__QUIET(&opts.quiet, "suppress progress reporting"),
 942                 OPT_STRING('b', NULL, &opts.new_branch, "branch",
 943                            "create and checkout a new branch"),
 944                 OPT_STRING('B', NULL, &opts.new_branch_force, "branch",
 945                            "create/reset and checkout a branch"),
 946                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "create reflog for new branch"),
 947                 OPT_BOOLEAN(0, "detach", &opts.force_detach, "detach the HEAD at named commit"),
 948                 OPT_SET_INT('t', "track",  &opts.track, "set upstream info for new branch",
 949                         BRANCH_TRACK_EXPLICIT),
 950                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, "new branch", "new unparented branch"),
 951                 OPT_SET_INT('2', "ours", &opts.writeout_stage, "checkout our version for unmerged files",
 952                             2),
 953                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "checkout their version for unmerged files",
 954                             3),
 955                 OPT__FORCE(&opts.force, "force checkout (throw away local modifications)"),
 956                 OPT_BOOLEAN('m', "merge", &opts.merge, "perform a 3-way merge with the new branch"),
 957                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, "update ignored files (default)"),
 958                 OPT_STRING(0, "conflict", &conflict_style, "style",
 959                            "conflict style (merge or diff3)"),
 960                 OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
 961                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
 962                   "second guess 'git checkout no-such-branch'",
 963                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
 964                 OPT_END(),
 965         };
 966
 967         memset(&opts, 0, sizeof(opts));
 968         memset(&new, 0, sizeof(new));
 969         opts.overwrite_ignore = 1;
 970
 971         gitmodules_config();
 972         git_config(git_checkout_config, &opts);
 973
 974         opts.track = BRANCH_TRACK_UNSPECIFIED;
 975
 976         argc = parse_options(argc, argv, prefix, options, checkout_usage,
 977                              PARSE_OPT_KEEP_DASHDASH);
 978
 979         /* we can assume from now on new_branch = !new_branch_force */
 980         if (opts.new_branch && opts.new_branch_force)
 981                 die(_("-B cannot be used with -b"));
 982
 983         /* copy -B over to -b, so that we can just check the latter */
 984         if (opts.new_branch_force)
 985                 opts.new_branch = opts.new_branch_force;
 986
 987         if (patch_mode && (opts.track > 0 || opts.new_branch
 988                            || opts.new_branch_log || opts.merge || opts.force
 989                            || opts.force_detach))
 990                 die (_("--patch is incompatible with all other options"));
 991
 992         if (opts.force_detach && (opts.new_branch || opts.new_orphan_branch))
 993                 die(_("--detach cannot be used with -b/-B/--orphan"));
 994         if (opts.force_detach && 0 < opts.track)
 995                 die(_("--detach cannot be used with -t"));
 996
 997         /* --track without -b should DWIM */
 998         if (0 < opts.track && !opts.new_branch) {
 999                 const char *argv0 = argv[0];
1000                 if (!argc || !strcmp(argv0, "--"))
1001                         die (_("--track needs a branch name"));
1002                 if (!prefixcmp(argv0, "refs/"))
1003                         argv0 += 5;
1004                 if (!prefixcmp(argv0, "remotes/"))
1005                         argv0 += 8;
1006                 argv0 = strchr(argv0, '/');
1007                 if (!argv0 || !argv0[1])
1008                         die (_("Missing branch name; try -b"));
1009                 opts.new_branch = argv0 + 1;
1010         }
1011
1012         if (opts.new_orphan_branch) {
1013                 if (opts.new_branch)
1014                         die(_("--orphan and -b|-B are mutually exclusive"));
1015                 if (opts.track > 0)
1016                         die(_("--orphan cannot be used with -t"));
1017                 opts.new_branch = opts.new_orphan_branch;
1018         }
1019
1020         if (conflict_style) {
1021                 opts.merge = 1; /* implied */
1022                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1023         }
1024
1025         if (opts.force && opts.merge)
1026                 die(_("git checkout: -f and -m are incompatible"));
1027
1028         /*
1029          * Extract branch name from command line arguments, so
1030          * all that is left is pathspecs.
1031          *
1032          * Handle
1033          *
1034          *  1) git checkout <tree> -- [<paths>]
1035          *  2) git checkout -- [<paths>]
1036          *  3) git checkout <something> [<paths>]
1037          *
1038          * including "last branch" syntax and DWIM-ery for names of
1039          * remote branches, erroring out for invalid or ambiguous cases.
1040          */
1041         if (argc) {
1042                 int dwim_ok =
1043                         !patch_mode &&
1044                         dwim_new_local_branch &&
1045                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1046                         !opts.new_branch;
1047                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1048                                 &new, &source_tree, rev, &opts.new_branch);
1049                 argv += n;
1050                 argc -= n;
1051         }
1052
1053         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
1054                 opts.track = git_branch_track;
1055
1056         if (argc) {
1057                 const char **pathspec = get_pathspec(prefix, argv);
1058
1059                 if (!pathspec)
1060                         die(_("invalid path specification"));
1061
1062                 if (patch_mode)
1063                         return interactive_checkout(new.name, pathspec, &opts);
1064
1065                 /* Checkout paths */
1066                 if (opts.new_branch) {
1067                         if (argc == 1) {
1068                                 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]);
1069                         } else {
1070                                 die(_("git checkout: updating paths is incompatible with switching branches."));
1071                         }
1072                 }
1073
1074                 if (opts.force_detach)
1075                         die(_("git checkout: --detach does not take a path argument"));
1076
1077                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1078                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index."));
1079
1080                 return checkout_paths(source_tree, pathspec, prefix, &opts);
1081         }
1082
1083         if (patch_mode)
1084                 return interactive_checkout(new.name, NULL, &opts);
1085
1086         if (opts.new_branch) {
1087                 struct strbuf buf = STRBUF_INIT;
1088
1089                 opts.branch_exists = validate_new_branchname(opts.new_branch, &buf,
1090                                                              !!opts.new_branch_force,
1091                                                              !!opts.new_branch_force);
1092
1093                 strbuf_release(&buf);
1094         }
1095
1096         if (new.name && !new.commit) {
1097                 die(_("Cannot switch branch to a non-commit."));
1098         }
1099         if (opts.writeout_stage)
1100                 die(_("--ours/--theirs is incompatible with switching branches."));
1101
1102         if (!new.commit && opts.new_branch) {
1103                 unsigned char rev[20];
1104                 int flag;
1105
1106                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
1107                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1108                         return switch_unborn_to_new_branch(&opts);
1109         }
1110         return switch_branches(&opts, &new);
1111 }