builtin/checkout.c

   1 #define USE_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "builtin.h"
   3 #include "advice.h"
   4 #include "blob.h"
   5 #include "branch.h"
   6 #include "cache-tree.h"
   7 #include "checkout.h"
   8 #include "commit.h"
   9 #include "config.h"
  10 #include "diff.h"
  11 #include "dir.h"
  12 #include "ll-merge.h"
  13 #include "lockfile.h"
  14 #include "merge-recursive.h"
  15 #include "object-store.h"
  16 #include "parse-options.h"
  17 #include "refs.h"
  18 #include "remote.h"
  19 #include "resolve-undo.h"
  20 #include "revision.h"
  21 #include "run-command.h"
  22 #include "submodule.h"
  23 #include "submodule-config.h"
  24 #include "tree.h"
  25 #include "tree-walk.h"
  26 #include "unpack-trees.h"
  27 #include "wt-status.h"
  28 #include "xdiff-interface.h"
  29
  30 static const char * const checkout_usage[] = {
  31         N_("git checkout [<options>] <branch>"),
  32         N_("git checkout [<options>] [<branch>] -- <file>..."),
  33         NULL,
  34 };
  35
  36 static const char * const switch_branch_usage[] = {
  37         N_("git switch [<options>] [<branch>]"),
  38         NULL,
  39 };
  40
  41 static const char * const restore_usage[] = {
  42         N_("git restore [<options>] [--source=<branch>] <file>..."),
  43         NULL,
  44 };
  45
  46 struct checkout_opts {
  47         int patch_mode;
  48         int quiet;
  49         int merge;
  50         int force;
  51         int force_detach;
  52         int implicit_detach;
  53         int writeout_stage;
  54         int overwrite_ignore;
  55         int ignore_skipworktree;
  56         int ignore_other_worktrees;
  57         int show_progress;
  58         int count_checkout_paths;
  59         int overlay_mode;
  60         int dwim_new_local_branch;
  61         int discard_changes;
  62         int accept_ref;
  63         int accept_pathspec;
  64         int switch_branch_doing_nothing_is_ok;
  65         int only_merge_on_switching_branches;
  66         int can_switch_when_in_progress;
  67         int orphan_from_empty_tree;
  68         int empty_pathspec_ok;
  69         int checkout_index;
  70         int checkout_worktree;
  71         const char *ignore_unmerged_opt;
  72         int ignore_unmerged;
  73
  74         const char *new_branch;
  75         const char *new_branch_force;
  76         const char *new_orphan_branch;
  77         int new_branch_log;
  78         enum branch_track track;
  79         struct diff_options diff_options;
  80         char *conflict_style;
  81
  82         int branch_exists;
  83         const char *prefix;
  84         struct pathspec pathspec;
  85         const char *from_treeish;
  86         struct tree *source_tree;
  87 };
  88
  89 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  90                               int changed)
  91 {
  92         return run_hook_le(NULL, "post-checkout",
  93                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  94                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  95                            changed ? "1" : "0", NULL);
  96         /* "new_commit" can be NULL when checking out from the index before
  97            a commit exists. */
  98
  99 }
 100
 101 static int update_some(const struct object_id *oid, struct strbuf *base,
 102                 const char *pathname, unsigned mode, int stage, void *context)
 103 {
 104         int len;
 105         struct cache_entry *ce;
 106         int pos;
 107
 108         if (S_ISDIR(mode))
 109                 return READ_TREE_RECURSIVE;
 110
 111         len = base->len + strlen(pathname);
 112         ce = make_empty_cache_entry(&the_index, len);
 113         oidcpy(&ce->oid, oid);
 114         memcpy(ce->name, base->buf, base->len);
 115         memcpy(ce->name + base->len, pathname, len - base->len);
 116         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
 117         ce->ce_namelen = len;
 118         ce->ce_mode = create_ce_mode(mode);
 119
 120         /*
 121          * If the entry is the same as the current index, we can leave the old
 122          * entry in place. Whether it is UPTODATE or not, checkout_entry will
 123          * do the right thing.
 124          */
 125         pos = cache_name_pos(ce->name, ce->ce_namelen);
 126         if (pos >= 0) {
 127                 struct cache_entry *old = active_cache[pos];
 128                 if (ce->ce_mode == old->ce_mode &&
 129                     oideq(&ce->oid, &old->oid)) {
 130                         old->ce_flags |= CE_UPDATE;
 131                         discard_cache_entry(ce);
 132                         return 0;
 133                 }
 134         }
 135
 136         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 137         return 0;
 138 }
 139
 140 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 141 {
 142         read_tree_recursive(the_repository, tree, "", 0, 0,
 143                             pathspec, update_some, NULL);
 144
 145         /* update the index with the given tree's info
 146          * for all args, expanding wildcards, and exit
 147          * with any non-zero return code.
 148          */
 149         return 0;
 150 }
 151
 152 static int skip_same_name(const struct cache_entry *ce, int pos)
 153 {
 154         while (++pos < active_nr &&
 155                !strcmp(active_cache[pos]->name, ce->name))
 156                 ; /* skip */
 157         return pos;
 158 }
 159
 160 static int check_stage(int stage, const struct cache_entry *ce, int pos,
 161                        int overlay_mode)
 162 {
 163         while (pos < active_nr &&
 164                !strcmp(active_cache[pos]->name, ce->name)) {
 165                 if (ce_stage(active_cache[pos]) == stage)
 166                         return 0;
 167                 pos++;
 168         }
 169         if (!overlay_mode)
 170                 return 0;
 171         if (stage == 2)
 172                 return error(_("path '%s' does not have our version"), ce->name);
 173         else
 174                 return error(_("path '%s' does not have their version"), ce->name);
 175 }
 176
 177 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 178 {
 179         unsigned seen = 0;
 180         const char *name = ce->name;
 181
 182         while (pos < active_nr) {
 183                 ce = active_cache[pos];
 184                 if (strcmp(name, ce->name))
 185                         break;
 186                 seen |= (1 << ce_stage(ce));
 187                 pos++;
 188         }
 189         if ((stages & seen) != stages)
 190                 return error(_("path '%s' does not have all necessary versions"),
 191                              name);
 192         return 0;
 193 }
 194
 195 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 196                           const struct checkout *state, int *nr_checkouts,
 197                           int overlay_mode)
 198 {
 199         while (pos < active_nr &&
 200                !strcmp(active_cache[pos]->name, ce->name)) {
 201                 if (ce_stage(active_cache[pos]) == stage)
 202                         return checkout_entry(active_cache[pos], state,
 203                                               NULL, nr_checkouts);
 204                 pos++;
 205         }
 206         if (!overlay_mode) {
 207                 unlink_entry(ce);
 208                 return 0;
 209         }
 210         if (stage == 2)
 211                 return error(_("path '%s' does not have our version"), ce->name);
 212         else
 213                 return error(_("path '%s' does not have their version"), ce->name);
 214 }
 215
 216 static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
 217 {
 218         struct cache_entry *ce = active_cache[pos];
 219         const char *path = ce->name;
 220         mmfile_t ancestor, ours, theirs;
 221         int status;
 222         struct object_id oid;
 223         mmbuffer_t result_buf;
 224         struct object_id threeway[3];
 225         unsigned mode = 0;
 226
 227         memset(threeway, 0, sizeof(threeway));
 228         while (pos < active_nr) {
 229                 int stage;
 230                 stage = ce_stage(ce);
 231                 if (!stage || strcmp(path, ce->name))
 232                         break;
 233                 oidcpy(&threeway[stage - 1], &ce->oid);
 234                 if (stage == 2)
 235                         mode = create_ce_mode(ce->ce_mode);
 236                 pos++;
 237                 ce = active_cache[pos];
 238         }
 239         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 240                 return error(_("path '%s' does not have necessary versions"), path);
 241
 242         read_mmblob(&ancestor, &threeway[0]);
 243         read_mmblob(&ours, &threeway[1]);
 244         read_mmblob(&theirs, &threeway[2]);
 245
 246         /*
 247          * NEEDSWORK: re-create conflicts from merges with
 248          * merge.renormalize set, too
 249          */
 250         status = ll_merge(&result_buf, path, &ancestor, "base",
 251                           &ours, "ours", &theirs, "theirs",
 252                           state->istate, NULL);
 253         free(ancestor.ptr);
 254         free(ours.ptr);
 255         free(theirs.ptr);
 256         if (status < 0 || !result_buf.ptr) {
 257                 free(result_buf.ptr);
 258                 return error(_("path '%s': cannot merge"), path);
 259         }
 260
 261         /*
 262          * NEEDSWORK:
 263          * There is absolutely no reason to write this as a blob object
 264          * and create a phony cache entry.  This hack is primarily to get
 265          * to the write_entry() machinery that massages the contents to
 266          * work-tree format and writes out which only allows it for a
 267          * cache entry.  The code in write_entry() needs to be refactored
 268          * to allow us to feed a <buffer, size, mode> instead of a cache
 269          * entry.  Such a refactoring would help merge_recursive as well
 270          * (it also writes the merge result to the object database even
 271          * when it may contain conflicts).
 272          */
 273         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 274                 die(_("Unable to add merge result for '%s'"), path);
 275         free(result_buf.ptr);
 276         ce = make_transient_cache_entry(mode, &oid, path, 2);
 277         if (!ce)
 278                 die(_("make_cache_entry failed for path '%s'"), path);
 279         status = checkout_entry(ce, state, NULL, nr_checkouts);
 280         discard_cache_entry(ce);
 281         return status;
 282 }
 283
 284 static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
 285                                          char *ps_matched,
 286                                          const struct checkout_opts *opts)
 287 {
 288         ce->ce_flags &= ~CE_MATCHED;
 289         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 290                 return;
 291         if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 292                 /*
 293                  * "git checkout tree-ish -- path", but this entry
 294                  * is in the original index but is not in tree-ish
 295                  * or does not match the pathspec; it will not be
 296                  * checked out to the working tree.  We will not do
 297                  * anything to this entry at all.
 298                  */
 299                 return;
 300         /*
 301          * Either this entry came from the tree-ish we are
 302          * checking the paths out of, or we are checking out
 303          * of the index.
 304          *
 305          * If it comes from the tree-ish, we already know it
 306          * matches the pathspec and could just stamp
 307          * CE_MATCHED to it from update_some(). But we still
 308          * need ps_matched and read_tree_recursive (and
 309          * eventually tree_entry_interesting) cannot fill
 310          * ps_matched yet. Once it can, we can avoid calling
 311          * match_pathspec() for _all_ entries when
 312          * opts->source_tree != NULL.
 313          */
 314         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 315                 ce->ce_flags |= CE_MATCHED;
 316 }
 317
 318 static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
 319                                             char *ps_matched,
 320                                             const struct checkout_opts *opts)
 321 {
 322         ce->ce_flags &= ~CE_MATCHED;
 323         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 324                 return;
 325         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
 326                 ce->ce_flags |= CE_MATCHED;
 327                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 328                         /*
 329                          * In overlay mode, but the path is not in
 330                          * tree-ish, which means we should remove it
 331                          * from the index and the working tree.
 332                          */
 333                         ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
 334         }
 335 }
 336
 337 static int checkout_worktree(const struct checkout_opts *opts)
 338 {
 339         struct checkout state = CHECKOUT_INIT;
 340         int nr_checkouts = 0, nr_unmerged = 0;
 341         int errs = 0;
 342         int pos;
 343
 344         state.force = 1;
 345         state.refresh_cache = 1;
 346         state.istate = &the_index;
 347
 348         enable_delayed_checkout(&state);
 349         for (pos = 0; pos < active_nr; pos++) {
 350                 struct cache_entry *ce = active_cache[pos];
 351                 if (ce->ce_flags & CE_MATCHED) {
 352                         if (!ce_stage(ce)) {
 353                                 errs |= checkout_entry(ce, &state,
 354                                                        NULL, &nr_checkouts);
 355                                 continue;
 356                         }
 357                         if (opts->writeout_stage)
 358                                 errs |= checkout_stage(opts->writeout_stage,
 359                                                        ce, pos,
 360                                                        &state,
 361                                                        &nr_checkouts, opts->overlay_mode);
 362                         else if (opts->merge)
 363                                 errs |= checkout_merged(pos, &state,
 364                                                         &nr_unmerged);
 365                         pos = skip_same_name(ce, pos) - 1;
 366                 }
 367         }
 368         remove_marked_cache_entries(&the_index, 1);
 369         remove_scheduled_dirs();
 370         errs |= finish_delayed_checkout(&state, &nr_checkouts);
 371
 372         if (opts->count_checkout_paths) {
 373                 if (nr_unmerged)
 374                         fprintf_ln(stderr, Q_("Recreated %d merge conflict",
 375                                               "Recreated %d merge conflicts",
 376                                               nr_unmerged),
 377                                    nr_unmerged);
 378                 if (opts->source_tree)
 379                         fprintf_ln(stderr, Q_("Updated %d path from %s",
 380                                               "Updated %d paths from %s",
 381                                               nr_checkouts),
 382                                    nr_checkouts,
 383                                    find_unique_abbrev(&opts->source_tree->object.oid,
 384                                                       DEFAULT_ABBREV));
 385                 else if (!nr_unmerged || nr_checkouts)
 386                         fprintf_ln(stderr, Q_("Updated %d path from the index",
 387                                               "Updated %d paths from the index",
 388                                               nr_checkouts),
 389                                    nr_checkouts);
 390         }
 391
 392         return errs;
 393 }
 394
 395 static int checkout_paths(const struct checkout_opts *opts,
 396                           const char *revision)
 397 {
 398         int pos;
 399         static char *ps_matched;
 400         struct object_id rev;
 401         struct commit *head;
 402         int errs = 0;
 403         struct lock_file lock_file = LOCK_INIT;
 404         int checkout_index;
 405
 406         trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
 407
 408         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 409                 die(_("'%s' cannot be used with updating paths"), "--track");
 410
 411         if (opts->new_branch_log)
 412                 die(_("'%s' cannot be used with updating paths"), "-l");
 413
 414         if (opts->ignore_unmerged && opts->patch_mode)
 415                 die(_("'%s' cannot be used with updating paths"),
 416                     opts->ignore_unmerged_opt);
 417
 418         if (opts->force_detach)
 419                 die(_("'%s' cannot be used with updating paths"), "--detach");
 420
 421         if (opts->merge && opts->patch_mode)
 422                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 423
 424         if (opts->ignore_unmerged && opts->merge)
 425                 die(_("'%s' cannot be used with %s"),
 426                     opts->ignore_unmerged_opt, "-m");
 427
 428         if (opts->new_branch)
 429                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 430                     opts->new_branch);
 431
 432         if (!opts->checkout_worktree && !opts->checkout_index)
 433                 die(_("neither '%s' or '%s' is specified"),
 434                     "--staged", "--worktree");
 435
 436         if (!opts->checkout_worktree && !opts->from_treeish)
 437                 die(_("'%s' must be used when '%s' is not specified"),
 438                     "--worktree", "--source");
 439
 440         if (opts->checkout_index && !opts->checkout_worktree &&
 441             opts->writeout_stage)
 442                 die(_("'%s' or '%s' cannot be used with %s"),
 443                     "--ours", "--theirs", "--staged");
 444
 445         if (opts->checkout_index && !opts->checkout_worktree &&
 446             opts->merge)
 447                 die(_("'%s' or '%s' cannot be used with %s"),
 448                     "--merge", "--conflict", "--staged");
 449
 450         if (opts->patch_mode) {
 451                 const char *patch_mode;
 452
 453                 if (opts->checkout_index && opts->checkout_worktree)
 454                         patch_mode = "--patch=checkout";
 455                 else if (opts->checkout_index && !opts->checkout_worktree)
 456                         patch_mode = "--patch=reset";
 457                 else if (!opts->checkout_index && opts->checkout_worktree)
 458                         patch_mode = "--patch=worktree";
 459                 else
 460                         BUG("either flag must have been set, worktree=%d, index=%d",
 461                             opts->checkout_worktree, opts->checkout_index);
 462                 return run_add_interactive(revision, patch_mode, &opts->pathspec);
 463         }
 464
 465         repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 466         if (read_cache_preload(&opts->pathspec) < 0)
 467                 return error(_("index file corrupt"));
 468
 469         if (opts->source_tree)
 470                 read_tree_some(opts->source_tree, &opts->pathspec);
 471
 472         ps_matched = xcalloc(opts->pathspec.nr, 1);
 473
 474         /*
 475          * Make sure all pathspecs participated in locating the paths
 476          * to be checked out.
 477          */
 478         for (pos = 0; pos < active_nr; pos++)
 479                 if (opts->overlay_mode)
 480                         mark_ce_for_checkout_overlay(active_cache[pos],
 481                                                      ps_matched,
 482                                                      opts);
 483                 else
 484                         mark_ce_for_checkout_no_overlay(active_cache[pos],
 485                                                         ps_matched,
 486                                                         opts);
 487
 488         if (report_path_error(ps_matched, &opts->pathspec)) {
 489                 free(ps_matched);
 490                 return 1;
 491         }
 492         free(ps_matched);
 493
 494         /* "checkout -m path" to recreate conflicted state */
 495         if (opts->merge)
 496                 unmerge_marked_index(&the_index);
 497
 498         /* Any unmerged paths? */
 499         for (pos = 0; pos < active_nr; pos++) {
 500                 const struct cache_entry *ce = active_cache[pos];
 501                 if (ce->ce_flags & CE_MATCHED) {
 502                         if (!ce_stage(ce))
 503                                 continue;
 504                         if (opts->ignore_unmerged) {
 505                                 if (!opts->quiet)
 506                                         warning(_("path '%s' is unmerged"), ce->name);
 507                         } else if (opts->writeout_stage) {
 508                                 errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
 509                         } else if (opts->merge) {
 510                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 511                         } else {
 512                                 errs = 1;
 513                                 error(_("path '%s' is unmerged"), ce->name);
 514                         }
 515                         pos = skip_same_name(ce, pos) - 1;
 516                 }
 517         }
 518         if (errs)
 519                 return 1;
 520
 521         /* Now we are committed to check them out */
 522         if (opts->checkout_worktree)
 523                 errs |= checkout_worktree(opts);
 524
 525         /*
 526          * Allow updating the index when checking out from the index.
 527          * This is to save new stat info.
 528          */
 529         if (opts->checkout_worktree && !opts->checkout_index && !opts->source_tree)
 530                 checkout_index = 1;
 531         else
 532                 checkout_index = opts->checkout_index;
 533
 534         if (checkout_index) {
 535                 if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 536                         die(_("unable to write new index file"));
 537         } else {
 538                 /*
 539                  * NEEDSWORK: if --worktree is not specified, we
 540                  * should save stat info of checked out files in the
 541                  * index to avoid the next (potentially costly)
 542                  * refresh. But it's a bit tricker to do...
 543                  */
 544                 rollback_lock_file(&lock_file);
 545         }
 546
 547         read_ref_full("HEAD", 0, &rev, NULL);
 548         head = lookup_commit_reference_gently(the_repository, &rev, 1);
 549
 550         errs |= post_checkout_hook(head, head, 0);
 551         return errs;
 552 }
 553
 554 static void show_local_changes(struct object *head,
 555                                const struct diff_options *opts)
 556 {
 557         struct rev_info rev;
 558         /* I think we want full paths, even if we're in a subdirectory. */
 559         repo_init_revisions(the_repository, &rev, NULL);
 560         rev.diffopt.flags = opts->flags;
 561         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 562         diff_setup_done(&rev.diffopt);
 563         add_pending_object(&rev, head, NULL);
 564         run_diff_index(&rev, 0);
 565 }
 566
 567 static void describe_detached_head(const char *msg, struct commit *commit)
 568 {
 569         struct strbuf sb = STRBUF_INIT;
 570
 571         if (!parse_commit(commit))
 572                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 573         if (print_sha1_ellipsis()) {
 574                 fprintf(stderr, "%s %s... %s\n", msg,
 575                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 576         } else {
 577                 fprintf(stderr, "%s %s %s\n", msg,
 578                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 579         }
 580         strbuf_release(&sb);
 581 }
 582
 583 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 584                       int worktree, int *writeout_error)
 585 {
 586         struct unpack_trees_options opts;
 587         struct tree_desc tree_desc;
 588
 589         memset(&opts, 0, sizeof(opts));
 590         opts.head_idx = -1;
 591         opts.update = worktree;
 592         opts.skip_unmerged = !worktree;
 593         opts.reset = 1;
 594         opts.merge = 1;
 595         opts.fn = oneway_merge;
 596         opts.verbose_update = o->show_progress;
 597         opts.src_index = &the_index;
 598         opts.dst_index = &the_index;
 599         parse_tree(tree);
 600         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 601         switch (unpack_trees(1, &tree_desc, &opts)) {
 602         case -2:
 603                 *writeout_error = 1;
 604                 /*
 605                  * We return 0 nevertheless, as the index is all right
 606                  * and more importantly we have made best efforts to
 607                  * update paths in the work tree, and we cannot revert
 608                  * them.
 609                  */
 610                 /* fallthrough */
 611         case 0:
 612                 return 0;
 613         default:
 614                 return 128;
 615         }
 616 }
 617
 618 struct branch_info {
 619         const char *name; /* The short name used */
 620         const char *path; /* The full name of a real branch */
 621         struct commit *commit; /* The named commit */
 622         /*
 623          * if not null the branch is detached because it's already
 624          * checked out in this checkout
 625          */
 626         char *checkout;
 627 };
 628
 629 static void setup_branch_path(struct branch_info *branch)
 630 {
 631         struct strbuf buf = STRBUF_INIT;
 632
 633         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 634         if (strcmp(buf.buf, branch->name))
 635                 branch->name = xstrdup(buf.buf);
 636         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 637         branch->path = strbuf_detach(&buf, NULL);
 638 }
 639
 640 static int merge_working_tree(const struct checkout_opts *opts,
 641                               struct branch_info *old_branch_info,
 642                               struct branch_info *new_branch_info,
 643                               int *writeout_error)
 644 {
 645         int ret;
 646         struct lock_file lock_file = LOCK_INIT;
 647         struct tree *new_tree;
 648
 649         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 650         if (read_cache_preload(NULL) < 0)
 651                 return error(_("index file corrupt"));
 652
 653         resolve_undo_clear();
 654         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 655                 if (new_branch_info->commit)
 656                         BUG("'switch --orphan' should never accept a commit as starting point");
 657                 new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
 658         } else
 659                 new_tree = get_commit_tree(new_branch_info->commit);
 660         if (opts->discard_changes) {
 661                 ret = reset_tree(new_tree, opts, 1, writeout_error);
 662                 if (ret)
 663                         return ret;
 664         } else {
 665                 struct tree_desc trees[2];
 666                 struct tree *tree;
 667                 struct unpack_trees_options topts;
 668
 669                 memset(&topts, 0, sizeof(topts));
 670                 topts.head_idx = -1;
 671                 topts.src_index = &the_index;
 672                 topts.dst_index = &the_index;
 673
 674                 setup_unpack_trees_porcelain(&topts, "checkout");
 675
 676                 refresh_cache(REFRESH_QUIET);
 677
 678                 if (unmerged_cache()) {
 679                         error(_("you need to resolve your current index first"));
 680                         return 1;
 681                 }
 682
 683                 /* 2-way merge to the new branch */
 684                 topts.initial_checkout = is_cache_unborn();
 685                 topts.update = 1;
 686                 topts.merge = 1;
 687                 topts.quiet = opts->merge && old_branch_info->commit;
 688                 topts.verbose_update = opts->show_progress;
 689                 topts.fn = twoway_merge;
 690                 if (opts->overwrite_ignore) {
 691                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 692                         topts.dir->flags |= DIR_SHOW_IGNORED;
 693                         setup_standard_excludes(topts.dir);
 694                 }
 695                 tree = parse_tree_indirect(old_branch_info->commit ?
 696                                            &old_branch_info->commit->object.oid :
 697                                            the_hash_algo->empty_tree);
 698                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 699                 parse_tree(new_tree);
 700                 tree = new_tree;
 701                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 702
 703                 ret = unpack_trees(2, trees, &topts);
 704                 clear_unpack_trees_porcelain(&topts);
 705                 if (ret == -1) {
 706                         /*
 707                          * Unpack couldn't do a trivial merge; either
 708                          * give up or do a real merge, depending on
 709                          * whether the merge flag was used.
 710                          */
 711                         struct tree *result;
 712                         struct tree *work;
 713                         struct tree *old_tree;
 714                         struct merge_options o;
 715                         struct strbuf sb = STRBUF_INIT;
 716
 717                         if (!opts->merge)
 718                                 return 1;
 719
 720                         /*
 721                          * Without old_branch_info->commit, the below is the same as
 722                          * the two-tree unpack we already tried and failed.
 723                          */
 724                         if (!old_branch_info->commit)
 725                                 return 1;
 726                         old_tree = get_commit_tree(old_branch_info->commit);
 727
 728                         if (repo_index_has_changes(the_repository, old_tree, &sb))
 729                                 die(_("cannot continue with staged changes in "
 730                                       "the following files:\n%s"), sb.buf);
 731                         strbuf_release(&sb);
 732
 733                         if (repo_index_has_changes(the_repository,
 734                                                    get_commit_tree(old_branch_info->commit),
 735                                                    &sb))
 736                                 warning(_("staged changes in the following files may be lost: %s"),
 737                                         sb.buf);
 738                         strbuf_release(&sb);
 739
 740                         /* Do more real merge */
 741
 742                         /*
 743                          * We update the index fully, then write the
 744                          * tree from the index, then merge the new
 745                          * branch with the current tree, with the old
 746                          * branch as the base. Then we reset the index
 747                          * (but not the working tree) to the new
 748                          * branch, leaving the working tree as the
 749                          * merged version, but skipping unmerged
 750                          * entries in the index.
 751                          */
 752
 753                         add_files_to_cache(NULL, NULL, 0);
 754                         /*
 755                          * NEEDSWORK: carrying over local changes
 756                          * when branches have different end-of-line
 757                          * normalization (or clean+smudge rules) is
 758                          * a pain; plumb in an option to set
 759                          * o.renormalize?
 760                          */
 761                         init_merge_options(&o, the_repository);
 762                         o.verbosity = 0;
 763                         work = write_tree_from_memory(&o);
 764
 765                         ret = reset_tree(new_tree,
 766                                          opts, 1,
 767                                          writeout_error);
 768                         if (ret)
 769                                 return ret;
 770                         o.ancestor = old_branch_info->name;
 771                         o.branch1 = new_branch_info->name;
 772                         o.branch2 = "local";
 773                         ret = merge_trees(&o,
 774                                           new_tree,
 775                                           work,
 776                                           old_tree,
 777                                           &result);
 778                         if (ret < 0)
 779                                 exit(128);
 780                         ret = reset_tree(new_tree,
 781                                          opts, 0,
 782                                          writeout_error);
 783                         strbuf_release(&o.obuf);
 784                         if (ret)
 785                                 return ret;
 786                 }
 787         }
 788
 789         if (!active_cache_tree)
 790                 active_cache_tree = cache_tree();
 791
 792         if (!cache_tree_fully_valid(active_cache_tree))
 793                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 794
 795         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 796                 die(_("unable to write new index file"));
 797
 798         if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
 799                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 800
 801         return 0;
 802 }
 803
 804 static void report_tracking(struct branch_info *new_branch_info)
 805 {
 806         struct strbuf sb = STRBUF_INIT;
 807         struct branch *branch = branch_get(new_branch_info->name);
 808
 809         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 810                 return;
 811         fputs(sb.buf, stdout);
 812         strbuf_release(&sb);
 813 }
 814
 815 static void update_refs_for_switch(const struct checkout_opts *opts,
 816                                    struct branch_info *old_branch_info,
 817                                    struct branch_info *new_branch_info)
 818 {
 819         struct strbuf msg = STRBUF_INIT;
 820         const char *old_desc, *reflog_msg;
 821         if (opts->new_branch) {
 822                 if (opts->new_orphan_branch) {
 823                         char *refname;
 824
 825                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 826                         if (opts->new_branch_log &&
 827                             !should_autocreate_reflog(refname)) {
 828                                 int ret;
 829                                 struct strbuf err = STRBUF_INIT;
 830
 831                                 ret = safe_create_reflog(refname, 1, &err);
 832                                 if (ret) {
 833                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 834                                                 opts->new_orphan_branch, err.buf);
 835                                         strbuf_release(&err);
 836                                         free(refname);
 837                                         return;
 838                                 }
 839                                 strbuf_release(&err);
 840                         }
 841                         free(refname);
 842                 }
 843                 else
 844                         create_branch(the_repository,
 845                                       opts->new_branch, new_branch_info->name,
 846                                       opts->new_branch_force ? 1 : 0,
 847                                       opts->new_branch_force ? 1 : 0,
 848                                       opts->new_branch_log,
 849                                       opts->quiet,
 850                                       opts->track);
 851                 new_branch_info->name = opts->new_branch;
 852                 setup_branch_path(new_branch_info);
 853         }
 854
 855         old_desc = old_branch_info->name;
 856         if (!old_desc && old_branch_info->commit)
 857                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 858
 859         reflog_msg = getenv("GIT_REFLOG_ACTION");
 860         if (!reflog_msg)
 861                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 862                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 863         else
 864                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 865
 866         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 867                 /* Nothing to do. */
 868         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 869                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 870                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 871                 if (!opts->quiet) {
 872                         if (old_branch_info->path &&
 873                             advice_detached_head && !opts->force_detach)
 874                                 detach_advice(new_branch_info->name);
 875                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 876                 }
 877         } else if (new_branch_info->path) {     /* Switch branches. */
 878                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 879                         die(_("unable to update HEAD"));
 880                 if (!opts->quiet) {
 881                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 882                                 if (opts->new_branch_force)
 883                                         fprintf(stderr, _("Reset branch '%s'\n"),
 884                                                 new_branch_info->name);
 885                                 else
 886                                         fprintf(stderr, _("Already on '%s'\n"),
 887                                                 new_branch_info->name);
 888                         } else if (opts->new_branch) {
 889                                 if (opts->branch_exists)
 890                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 891                                 else
 892                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 893                         } else {
 894                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 895                                         new_branch_info->name);
 896                         }
 897                 }
 898                 if (old_branch_info->path && old_branch_info->name) {
 899                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 900                                 delete_reflog(old_branch_info->path);
 901                 }
 902         }
 903         remove_branch_state(the_repository, !opts->quiet);
 904         strbuf_release(&msg);
 905         if (!opts->quiet &&
 906             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 907                 report_tracking(new_branch_info);
 908 }
 909
 910 static int add_pending_uninteresting_ref(const char *refname,
 911                                          const struct object_id *oid,
 912                                          int flags, void *cb_data)
 913 {
 914         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 915         return 0;
 916 }
 917
 918 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 919 {
 920         strbuf_addstr(sb, "  ");
 921         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 922         strbuf_addch(sb, ' ');
 923         if (!parse_commit(commit))
 924                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 925         strbuf_addch(sb, '\n');
 926 }
 927
 928 #define ORPHAN_CUTOFF 4
 929 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 930 {
 931         struct commit *c, *last = NULL;
 932         struct strbuf sb = STRBUF_INIT;
 933         int lost = 0;
 934         while ((c = get_revision(revs)) != NULL) {
 935                 if (lost < ORPHAN_CUTOFF)
 936                         describe_one_orphan(&sb, c);
 937                 last = c;
 938                 lost++;
 939         }
 940         if (ORPHAN_CUTOFF < lost) {
 941                 int more = lost - ORPHAN_CUTOFF;
 942                 if (more == 1)
 943                         describe_one_orphan(&sb, last);
 944                 else
 945                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 946         }
 947
 948         fprintf(stderr,
 949                 Q_(
 950                 /* The singular version */
 951                 "Warning: you are leaving %d commit behind, "
 952                 "not connected to\n"
 953                 "any of your branches:\n\n"
 954                 "%s\n",
 955                 /* The plural version */
 956                 "Warning: you are leaving %d commits behind, "
 957                 "not connected to\n"
 958                 "any of your branches:\n\n"
 959                 "%s\n",
 960                 /* Give ngettext() the count */
 961                 lost),
 962                 lost,
 963                 sb.buf);
 964         strbuf_release(&sb);
 965
 966         if (advice_detached_head)
 967                 fprintf(stderr,
 968                         Q_(
 969                         /* The singular version */
 970                         "If you want to keep it by creating a new branch, "
 971                         "this may be a good time\nto do so with:\n\n"
 972                         " git branch <new-branch-name> %s\n\n",
 973                         /* The plural version */
 974                         "If you want to keep them by creating a new branch, "
 975                         "this may be a good time\nto do so with:\n\n"
 976                         " git branch <new-branch-name> %s\n\n",
 977                         /* Give ngettext() the count */
 978                         lost),
 979                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 980 }
 981
 982 /*
 983  * We are about to leave commit that was at the tip of a detached
 984  * HEAD.  If it is not reachable from any ref, this is the last chance
 985  * for the user to do so without resorting to reflog.
 986  */
 987 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 988 {
 989         struct rev_info revs;
 990         struct object *object = &old_commit->object;
 991
 992         repo_init_revisions(the_repository, &revs, NULL);
 993         setup_revisions(0, NULL, &revs, NULL);
 994
 995         object->flags &= ~UNINTERESTING;
 996         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 997
 998         for_each_ref(add_pending_uninteresting_ref, &revs);
 999         if (new_commit)
1000                 add_pending_oid(&revs, "HEAD",
1001                                 &new_commit->object.oid,
1002                                 UNINTERESTING);
1003
1004         if (prepare_revision_walk(&revs))
1005                 die(_("internal error in revision walk"));
1006         if (!(old_commit->object.flags & UNINTERESTING))
1007                 suggest_reattach(old_commit, &revs);
1008         else
1009                 describe_detached_head(_("Previous HEAD position was"), old_commit);
1010
1011         /* Clean up objects used, as they will be reused. */
1012         clear_commit_marks_all(ALL_REV_FLAGS);
1013 }
1014
1015 static int switch_branches(const struct checkout_opts *opts,
1016                            struct branch_info *new_branch_info)
1017 {
1018         int ret = 0;
1019         struct branch_info old_branch_info;
1020         void *path_to_free;
1021         struct object_id rev;
1022         int flag, writeout_error = 0;
1023         int do_merge = 1;
1024
1025         trace2_cmd_mode("branch");
1026
1027         memset(&old_branch_info, 0, sizeof(old_branch_info));
1028         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1029         if (old_branch_info.path)
1030                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1031         if (!(flag & REF_ISSYMREF))
1032                 old_branch_info.path = NULL;
1033
1034         if (old_branch_info.path)
1035                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1036
1037         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
1038                 if (new_branch_info->name)
1039                         BUG("'switch --orphan' should never accept a commit as starting point");
1040                 new_branch_info->commit = NULL;
1041                 new_branch_info->name = "(empty)";
1042                 do_merge = 1;
1043         }
1044
1045         if (!new_branch_info->name) {
1046                 new_branch_info->name = "HEAD";
1047                 new_branch_info->commit = old_branch_info.commit;
1048                 if (!new_branch_info->commit)
1049                         die(_("You are on a branch yet to be born"));
1050                 parse_commit_or_die(new_branch_info->commit);
1051
1052                 if (opts->only_merge_on_switching_branches)
1053                         do_merge = 0;
1054         }
1055
1056         if (do_merge) {
1057                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1058                 if (ret) {
1059                         free(path_to_free);
1060                         return ret;
1061                 }
1062         }
1063
1064         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1065                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1066
1067         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1068
1069         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1070         free(path_to_free);
1071         return ret || writeout_error;
1072 }
1073
1074 static int git_checkout_config(const char *var, const char *value, void *cb)
1075 {
1076         if (!strcmp(var, "diff.ignoresubmodules")) {
1077                 struct checkout_opts *opts = cb;
1078                 handle_ignore_submodules_arg(&opts->diff_options, value);
1079                 return 0;
1080         }
1081
1082         if (starts_with(var, "submodule."))
1083                 return git_default_submodule_config(var, value, NULL);
1084
1085         return git_xmerge_config(var, value, NULL);
1086 }
1087
1088 static void setup_new_branch_info_and_source_tree(
1089         struct branch_info *new_branch_info,
1090         struct checkout_opts *opts,
1091         struct object_id *rev,
1092         const char *arg)
1093 {
1094         struct tree **source_tree = &opts->source_tree;
1095         struct object_id branch_rev;
1096
1097         new_branch_info->name = arg;
1098         setup_branch_path(new_branch_info);
1099
1100         if (!check_refname_format(new_branch_info->path, 0) &&
1101             !read_ref(new_branch_info->path, &branch_rev))
1102                 oidcpy(rev, &branch_rev);
1103         else
1104                 new_branch_info->path = NULL; /* not an existing branch */
1105
1106         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1107         if (!new_branch_info->commit) {
1108                 /* not a commit */
1109                 *source_tree = parse_tree_indirect(rev);
1110         } else {
1111                 parse_commit_or_die(new_branch_info->commit);
1112                 *source_tree = get_commit_tree(new_branch_info->commit);
1113         }
1114 }
1115
1116 static int parse_branchname_arg(int argc, const char **argv,
1117                                 int dwim_new_local_branch_ok,
1118                                 struct branch_info *new_branch_info,
1119                                 struct checkout_opts *opts,
1120                                 struct object_id *rev,
1121                                 int *dwim_remotes_matched)
1122 {
1123         const char **new_branch = &opts->new_branch;
1124         int argcount = 0;
1125         const char *arg;
1126         int dash_dash_pos;
1127         int has_dash_dash = 0;
1128         int i;
1129
1130         /*
1131          * case 1: git checkout <ref> -- [<paths>]
1132          *
1133          *   <ref> must be a valid tree, everything after the '--' must be
1134          *   a path.
1135          *
1136          * case 2: git checkout -- [<paths>]
1137          *
1138          *   everything after the '--' must be paths.
1139          *
1140          * case 3: git checkout <something> [--]
1141          *
1142          *   (a) If <something> is a commit, that is to
1143          *       switch to the branch or detach HEAD at it.  As a special case,
1144          *       if <something> is A...B (missing A or B means HEAD but you can
1145          *       omit at most one side), and if there is a unique merge base
1146          *       between A and B, A...B names that merge base.
1147          *
1148          *   (b) If <something> is _not_ a commit, either "--" is present
1149          *       or <something> is not a path, no -t or -b was given, and
1150          *       and there is a tracking branch whose name is <something>
1151          *       in one and only one remote (or if the branch exists on the
1152          *       remote named in checkout.defaultRemote), then this is a
1153          *       short-hand to fork local <something> from that
1154          *       remote-tracking branch.
1155          *
1156          *   (c) Otherwise, if "--" is present, treat it like case (1).
1157          *
1158          *   (d) Otherwise :
1159          *       - if it's a reference, treat it like case (1)
1160          *       - else if it's a path, treat it like case (2)
1161          *       - else: fail.
1162          *
1163          * case 4: git checkout <something> <paths>
1164          *
1165          *   The first argument must not be ambiguous.
1166          *   - If it's *only* a reference, treat it like case (1).
1167          *   - If it's only a path, treat it like case (2).
1168          *   - else: fail.
1169          *
1170          */
1171         if (!argc)
1172                 return 0;
1173
1174         if (!opts->accept_pathspec) {
1175                 if (argc > 1)
1176                         die(_("only one reference expected"));
1177                 has_dash_dash = 1; /* helps disambiguate */
1178         }
1179
1180         arg = argv[0];
1181         dash_dash_pos = -1;
1182         for (i = 0; i < argc; i++) {
1183                 if (opts->accept_pathspec && !strcmp(argv[i], "--")) {
1184                         dash_dash_pos = i;
1185                         break;
1186                 }
1187         }
1188         if (dash_dash_pos == 0)
1189                 return 1; /* case (2) */
1190         else if (dash_dash_pos == 1)
1191                 has_dash_dash = 1; /* case (3) or (1) */
1192         else if (dash_dash_pos >= 2)
1193                 die(_("only one reference expected, %d given."), dash_dash_pos);
1194         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1195
1196         if (!strcmp(arg, "-"))
1197                 arg = "@{-1}";
1198
1199         if (get_oid_mb(arg, rev)) {
1200                 /*
1201                  * Either case (3) or (4), with <something> not being
1202                  * a commit, or an attempt to use case (1) with an
1203                  * invalid ref.
1204                  *
1205                  * It's likely an error, but we need to find out if
1206                  * we should auto-create the branch, case (3).(b).
1207                  */
1208                 int recover_with_dwim = dwim_new_local_branch_ok;
1209
1210                 int could_be_checkout_paths = !has_dash_dash &&
1211                         check_filename(opts->prefix, arg);
1212
1213                 if (!has_dash_dash && !no_wildcard(arg))
1214                         recover_with_dwim = 0;
1215
1216                 /*
1217                  * Accept "git checkout foo", "git checkout foo --"
1218                  * and "git switch foo" as candidates for dwim.
1219                  */
1220                 if (!(argc == 1 && !has_dash_dash) &&
1221                     !(argc == 2 && has_dash_dash) &&
1222                     opts->accept_pathspec)
1223                         recover_with_dwim = 0;
1224
1225                 if (recover_with_dwim) {
1226                         const char *remote = unique_tracking_name(arg, rev,
1227                                                                   dwim_remotes_matched);
1228                         if (remote) {
1229                                 if (could_be_checkout_paths)
1230                                         die(_("'%s' could be both a local file and a tracking branch.\n"
1231                                               "Please use -- (and optionally --no-guess) to disambiguate"),
1232                                             arg);
1233                                 *new_branch = arg;
1234                                 arg = remote;
1235                                 /* DWIMmed to create local branch, case (3).(b) */
1236                         } else {
1237                                 recover_with_dwim = 0;
1238                         }
1239                 }
1240
1241                 if (!recover_with_dwim) {
1242                         if (has_dash_dash)
1243                                 die(_("invalid reference: %s"), arg);
1244                         return argcount;
1245                 }
1246         }
1247
1248         /* we can't end up being in (2) anymore, eat the argument */
1249         argcount++;
1250         argv++;
1251         argc--;
1252
1253         setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1254
1255         if (!opts->source_tree)                   /* case (1): want a tree */
1256                 die(_("reference is not a tree: %s"), arg);
1257
1258         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1259                 /*
1260                  * Do not complain the most common case
1261                  *      git checkout branch
1262                  * even if there happen to be a file called 'branch';
1263                  * it would be extremely annoying.
1264                  */
1265                 if (argc)
1266                         verify_non_filename(opts->prefix, arg);
1267         } else if (opts->accept_pathspec) {
1268                 argcount++;
1269                 argv++;
1270                 argc--;
1271         }
1272
1273         return argcount;
1274 }
1275
1276 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1277 {
1278         int status;
1279         struct strbuf branch_ref = STRBUF_INIT;
1280
1281         trace2_cmd_mode("unborn");
1282
1283         if (!opts->new_branch)
1284                 die(_("You are on a branch yet to be born"));
1285         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1286         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1287         strbuf_release(&branch_ref);
1288         if (!opts->quiet)
1289                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1290                         opts->new_branch);
1291         return status;
1292 }
1293
1294 static void die_expecting_a_branch(const struct branch_info *branch_info)
1295 {
1296         struct object_id oid;
1297         char *to_free;
1298
1299         if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free) == 1) {
1300                 const char *ref = to_free;
1301
1302                 if (skip_prefix(ref, "refs/tags/", &ref))
1303                         die(_("a branch is expected, got tag '%s'"), ref);
1304                 if (skip_prefix(ref, "refs/remotes/", &ref))
1305                         die(_("a branch is expected, got remote branch '%s'"), ref);
1306                 die(_("a branch is expected, got '%s'"), ref);
1307         }
1308         if (branch_info->commit)
1309                 die(_("a branch is expected, got commit '%s'"), branch_info->name);
1310         /*
1311          * This case should never happen because we already die() on
1312          * non-commit, but just in case.
1313          */
1314         die(_("a branch is expected, got '%s'"), branch_info->name);
1315 }
1316
1317 static void die_if_some_operation_in_progress(void)
1318 {
1319         struct wt_status_state state;
1320
1321         memset(&state, 0, sizeof(state));
1322         wt_status_get_state(the_repository, &state, 0);
1323
1324         if (state.merge_in_progress)
1325                 die(_("cannot switch branch while merging\n"
1326                       "Consider \"git merge --quit\" "
1327                       "or \"git worktree add\"."));
1328         if (state.am_in_progress)
1329                 die(_("cannot switch branch in the middle of an am session\n"
1330                       "Consider \"git am --quit\" "
1331                       "or \"git worktree add\"."));
1332         if (state.rebase_interactive_in_progress || state.rebase_in_progress)
1333                 die(_("cannot switch branch while rebasing\n"
1334                       "Consider \"git rebase --quit\" "
1335                       "or \"git worktree add\"."));
1336         if (state.cherry_pick_in_progress)
1337                 die(_("cannot switch branch while cherry-picking\n"
1338                       "Consider \"git cherry-pick --quit\" "
1339                       "or \"git worktree add\"."));
1340         if (state.revert_in_progress)
1341                 die(_("cannot switch branch while reverting\n"
1342                       "Consider \"git revert --quit\" "
1343                       "or \"git worktree add\"."));
1344         if (state.bisect_in_progress)
1345                 warning(_("you are switching branch while bisecting"));
1346 }
1347
1348 static int checkout_branch(struct checkout_opts *opts,
1349                            struct branch_info *new_branch_info)
1350 {
1351         if (opts->pathspec.nr)
1352                 die(_("paths cannot be used with switching branches"));
1353
1354         if (opts->patch_mode)
1355                 die(_("'%s' cannot be used with switching branches"),
1356                     "--patch");
1357
1358         if (opts->overlay_mode != -1)
1359                 die(_("'%s' cannot be used with switching branches"),
1360                     "--[no]-overlay");
1361
1362         if (opts->writeout_stage)
1363                 die(_("'%s' cannot be used with switching branches"),
1364                     "--ours/--theirs");
1365
1366         if (opts->force && opts->merge)
1367                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1368
1369         if (opts->discard_changes && opts->merge)
1370                 die(_("'%s' cannot be used with '%s'"), "--discard-changes", "--merge");
1371
1372         if (opts->force_detach && opts->new_branch)
1373                 die(_("'%s' cannot be used with '%s'"),
1374                     "--detach", "-b/-B/--orphan");
1375
1376         if (opts->new_orphan_branch) {
1377                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1378                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1379                 if (opts->orphan_from_empty_tree && new_branch_info->name)
1380                         die(_("'%s' cannot take <start-point>"), "--orphan");
1381         } else if (opts->force_detach) {
1382                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1383                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1384         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1385                 opts->track = git_branch_track;
1386
1387         if (new_branch_info->name && !new_branch_info->commit)
1388                 die(_("Cannot switch branch to a non-commit '%s'"),
1389                     new_branch_info->name);
1390
1391         if (!opts->switch_branch_doing_nothing_is_ok &&
1392             !new_branch_info->name &&
1393             !opts->new_branch &&
1394             !opts->force_detach)
1395                 die(_("missing branch or commit argument"));
1396
1397         if (!opts->implicit_detach &&
1398             !opts->force_detach &&
1399             !opts->new_branch &&
1400             !opts->new_branch_force &&
1401             new_branch_info->name &&
1402             !new_branch_info->path)
1403                 die_expecting_a_branch(new_branch_info);
1404
1405         if (!opts->can_switch_when_in_progress)
1406                 die_if_some_operation_in_progress();
1407
1408         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1409             !opts->ignore_other_worktrees) {
1410                 int flag;
1411                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1412                 if (head_ref &&
1413                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1414                         die_if_checked_out(new_branch_info->path, 1);
1415                 free(head_ref);
1416         }
1417
1418         if (!new_branch_info->commit && opts->new_branch) {
1419                 struct object_id rev;
1420                 int flag;
1421
1422                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1423                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1424                         return switch_unborn_to_new_branch(opts);
1425         }
1426         return switch_branches(opts, new_branch_info);
1427 }
1428
1429 static struct option *add_common_options(struct checkout_opts *opts,
1430                                          struct option *prevopts)
1431 {
1432         struct option options[] = {
1433                 OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1434                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1435                             "checkout", "control recursive updating of submodules",
1436                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1437                 OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1438                 OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1439                 OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1440                            N_("conflict style (merge or diff3)")),
1441                 OPT_END()
1442         };
1443         struct option *newopts = parse_options_concat(prevopts, options);
1444         free(prevopts);
1445         return newopts;
1446 }
1447
1448 static struct option *add_common_switch_branch_options(
1449         struct checkout_opts *opts, struct option *prevopts)
1450 {
1451         struct option options[] = {
1452                 OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1453                 OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1454                         BRANCH_TRACK_EXPLICIT),
1455                 OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1456                            PARSE_OPT_NOCOMPLETE),
1457                 OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1458                 OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1459                            N_("update ignored files (default)"),
1460                            PARSE_OPT_NOCOMPLETE),
1461                 OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1462                          N_("do not check if another worktree is holding the given ref")),
1463                 OPT_END()
1464         };
1465         struct option *newopts = parse_options_concat(prevopts, options);
1466         free(prevopts);
1467         return newopts;
1468 }
1469
1470 static struct option *add_checkout_path_options(struct checkout_opts *opts,
1471                                                 struct option *prevopts)
1472 {
1473         struct option options[] = {
1474                 OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1475                               N_("checkout our version for unmerged files"),
1476                               2, PARSE_OPT_NONEG),
1477                 OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1478                               N_("checkout their version for unmerged files"),
1479                               3, PARSE_OPT_NONEG),
1480                 OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1481                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1482                          N_("do not limit pathspecs to sparse entries only")),
1483                 OPT_END()
1484         };
1485         struct option *newopts = parse_options_concat(prevopts, options);
1486         free(prevopts);
1487         return newopts;
1488 }
1489
1490 static int checkout_main(int argc, const char **argv, const char *prefix,
1491                          struct checkout_opts *opts, struct option *options,
1492                          const char * const usagestr[])
1493 {
1494         struct branch_info new_branch_info;
1495         int dwim_remotes_matched = 0;
1496         int parseopt_flags = 0;
1497
1498         memset(&new_branch_info, 0, sizeof(new_branch_info));
1499         opts->overwrite_ignore = 1;
1500         opts->prefix = prefix;
1501         opts->show_progress = -1;
1502
1503         git_config(git_checkout_config, opts);
1504
1505         opts->track = BRANCH_TRACK_UNSPECIFIED;
1506
1507         if (!opts->accept_pathspec && !opts->accept_ref)
1508                 BUG("make up your mind, you need to take _something_");
1509         if (opts->accept_pathspec && opts->accept_ref)
1510                 parseopt_flags = PARSE_OPT_KEEP_DASHDASH;
1511
1512         argc = parse_options(argc, argv, prefix, options,
1513                              usagestr, parseopt_flags);
1514
1515         if (opts->show_progress < 0) {
1516                 if (opts->quiet)
1517                         opts->show_progress = 0;
1518                 else
1519                         opts->show_progress = isatty(2);
1520         }
1521
1522         if (opts->conflict_style) {
1523                 opts->merge = 1; /* implied */
1524                 git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1525         }
1526         if (opts->force) {
1527                 opts->discard_changes = 1;
1528                 opts->ignore_unmerged_opt = "--force";
1529                 opts->ignore_unmerged = 1;
1530         }
1531
1532         if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1533                 die(_("-b, -B and --orphan are mutually exclusive"));
1534
1535         if (opts->overlay_mode == 1 && opts->patch_mode)
1536                 die(_("-p and --overlay are mutually exclusive"));
1537
1538         if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
1539                 if (opts->checkout_index < 0)
1540                         opts->checkout_index = 0;
1541                 if (opts->checkout_worktree < 0)
1542                         opts->checkout_worktree = 0;
1543         } else {
1544                 if (opts->checkout_index < 0)
1545                         opts->checkout_index = -opts->checkout_index - 1;
1546                 if (opts->checkout_worktree < 0)
1547                         opts->checkout_worktree = -opts->checkout_worktree - 1;
1548         }
1549         if (opts->checkout_index < 0 || opts->checkout_worktree < 0)
1550                 BUG("these flags should be non-negative by now");
1551         /*
1552          * convenient shortcut: "git restore --staged" equals
1553          * "git restore --staged --source HEAD"
1554          */
1555         if (!opts->from_treeish && opts->checkout_index && !opts->checkout_worktree)
1556                 opts->from_treeish = "HEAD";
1557
1558         /*
1559          * From here on, new_branch will contain the branch to be checked out,
1560          * and new_branch_force and new_orphan_branch will tell us which one of
1561          * -b/-B/--orphan is being used.
1562          */
1563         if (opts->new_branch_force)
1564                 opts->new_branch = opts->new_branch_force;
1565
1566         if (opts->new_orphan_branch)
1567                 opts->new_branch = opts->new_orphan_branch;
1568
1569         /* --track without -b/-B/--orphan should DWIM */
1570         if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1571                 const char *argv0 = argv[0];
1572                 if (!argc || !strcmp(argv0, "--"))
1573                         die(_("--track needs a branch name"));
1574                 skip_prefix(argv0, "refs/", &argv0);
1575                 skip_prefix(argv0, "remotes/", &argv0);
1576                 argv0 = strchr(argv0, '/');
1577                 if (!argv0 || !argv0[1])
1578                         die(_("missing branch name; try -b"));
1579                 opts->new_branch = argv0 + 1;
1580         }
1581
1582         /*
1583          * Extract branch name from command line arguments, so
1584          * all that is left is pathspecs.
1585          *
1586          * Handle
1587          *
1588          *  1) git checkout <tree> -- [<paths>]
1589          *  2) git checkout -- [<paths>]
1590          *  3) git checkout <something> [<paths>]
1591          *
1592          * including "last branch" syntax and DWIM-ery for names of
1593          * remote branches, erroring out for invalid or ambiguous cases.
1594          */
1595         if (argc && opts->accept_ref) {
1596                 struct object_id rev;
1597                 int dwim_ok =
1598                         !opts->patch_mode &&
1599                         opts->dwim_new_local_branch &&
1600                         opts->track == BRANCH_TRACK_UNSPECIFIED &&
1601                         !opts->new_branch;
1602                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1603                                              &new_branch_info, opts, &rev,
1604                                              &dwim_remotes_matched);
1605                 argv += n;
1606                 argc -= n;
1607         } else if (!opts->accept_ref && opts->from_treeish) {
1608                 struct object_id rev;
1609
1610                 if (get_oid_mb(opts->from_treeish, &rev))
1611                         die(_("could not resolve %s"), opts->from_treeish);
1612
1613                 setup_new_branch_info_and_source_tree(&new_branch_info,
1614                                                       opts, &rev,
1615                                                       opts->from_treeish);
1616
1617                 if (!opts->source_tree)
1618                         die(_("reference is not a tree: %s"), opts->from_treeish);
1619         }
1620
1621         if (opts->accept_pathspec && !opts->empty_pathspec_ok && !argc &&
1622             !opts->patch_mode)  /* patch mode is special */
1623                 die(_("you must specify path(s) to restore"));
1624
1625         if (argc) {
1626                 parse_pathspec(&opts->pathspec, 0,
1627                                opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1628                                prefix, argv);
1629
1630                 if (!opts->pathspec.nr)
1631                         die(_("invalid path specification"));
1632
1633                 /*
1634                  * Try to give more helpful suggestion.
1635                  * new_branch && argc > 1 will be caught later.
1636                  */
1637                 if (opts->new_branch && argc == 1)
1638                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1639                                 argv[0], opts->new_branch);
1640
1641                 if (opts->force_detach)
1642                         die(_("git checkout: --detach does not take a path argument '%s'"),
1643                             argv[0]);
1644
1645                 if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1646                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1647                               "checking out of the index."));
1648         }
1649
1650         if (opts->new_branch) {
1651                 struct strbuf buf = STRBUF_INIT;
1652
1653                 if (opts->new_branch_force)
1654                         opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1655                 else
1656                         opts->branch_exists =
1657                                 validate_new_branchname(opts->new_branch, &buf, 0);
1658                 strbuf_release(&buf);
1659         }
1660
1661         UNLEAK(opts);
1662         if (opts->patch_mode || opts->pathspec.nr) {
1663                 int ret = checkout_paths(opts, new_branch_info.name);
1664                 if (ret && dwim_remotes_matched > 1 &&
1665                     advice_checkout_ambiguous_remote_branch_name)
1666                         advise(_("'%s' matched more than one remote tracking branch.\n"
1667                                  "We found %d remotes with a reference that matched. So we fell back\n"
1668                                  "on trying to resolve the argument as a path, but failed there too!\n"
1669                                  "\n"
1670                                  "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1671                                  "you can do so by fully qualifying the name with the --track option:\n"
1672                                  "\n"
1673                                  "    git checkout --track origin/<name>\n"
1674                                  "\n"
1675                                  "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1676                                  "one remote, e.g. the 'origin' remote, consider setting\n"
1677                                  "checkout.defaultRemote=origin in your config."),
1678                                argv[0],
1679                                dwim_remotes_matched);
1680                 return ret;
1681         } else {
1682                 return checkout_branch(opts, &new_branch_info);
1683         }
1684 }
1685
1686 int cmd_checkout(int argc, const char **argv, const char *prefix)
1687 {
1688         struct checkout_opts opts;
1689         struct option *options;
1690         struct option checkout_options[] = {
1691                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1692                            N_("create and checkout a new branch")),
1693                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1694                            N_("create/reset and checkout a branch")),
1695                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1696                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1697                          N_("second guess 'git checkout <no-such-branch>' (default)")),
1698                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1699                 OPT_END()
1700         };
1701         int ret;
1702
1703         memset(&opts, 0, sizeof(opts));
1704         opts.dwim_new_local_branch = 1;
1705         opts.switch_branch_doing_nothing_is_ok = 1;
1706         opts.only_merge_on_switching_branches = 0;
1707         opts.accept_ref = 1;
1708         opts.accept_pathspec = 1;
1709         opts.implicit_detach = 1;
1710         opts.can_switch_when_in_progress = 1;
1711         opts.orphan_from_empty_tree = 0;
1712         opts.empty_pathspec_ok = 1;
1713         opts.overlay_mode = -1;
1714         opts.checkout_index = -2;    /* default on */
1715         opts.checkout_worktree = -2; /* default on */
1716
1717         options = parse_options_dup(checkout_options);
1718         options = add_common_options(&opts, options);
1719         options = add_common_switch_branch_options(&opts, options);
1720         options = add_checkout_path_options(&opts, options);
1721
1722         ret = checkout_main(argc, argv, prefix, &opts,
1723                             options, checkout_usage);
1724         FREE_AND_NULL(options);
1725         return ret;
1726 }
1727
1728 int cmd_switch(int argc, const char **argv, const char *prefix)
1729 {
1730         struct checkout_opts opts;
1731         struct option *options = NULL;
1732         struct option switch_options[] = {
1733                 OPT_STRING('c', "create", &opts.new_branch, N_("branch"),
1734                            N_("create and switch to a new branch")),
1735                 OPT_STRING('C', "force-create", &opts.new_branch_force, N_("branch"),
1736                            N_("create/reset and switch to a branch")),
1737                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1738                          N_("second guess 'git switch <no-such-branch>'")),
1739                 OPT_BOOL(0, "discard-changes", &opts.discard_changes,
1740                          N_("throw away local modifications")),
1741                 OPT_END()
1742         };
1743         int ret;
1744
1745         memset(&opts, 0, sizeof(opts));
1746         opts.dwim_new_local_branch = 1;
1747         opts.accept_ref = 1;
1748         opts.accept_pathspec = 0;
1749         opts.switch_branch_doing_nothing_is_ok = 0;
1750         opts.only_merge_on_switching_branches = 1;
1751         opts.implicit_detach = 0;
1752         opts.can_switch_when_in_progress = 0;
1753         opts.orphan_from_empty_tree = 1;
1754         opts.overlay_mode = -1;
1755
1756         options = parse_options_dup(switch_options);
1757         options = add_common_options(&opts, options);
1758         options = add_common_switch_branch_options(&opts, options);
1759
1760         ret = checkout_main(argc, argv, prefix, &opts,
1761                             options, switch_branch_usage);
1762         FREE_AND_NULL(options);
1763         return ret;
1764 }
1765
1766 int cmd_restore(int argc, const char **argv, const char *prefix)
1767 {
1768         struct checkout_opts opts;
1769         struct option *options;
1770         struct option restore_options[] = {
1771                 OPT_STRING('s', "source", &opts.from_treeish, "<tree-ish>",
1772                            N_("which tree-ish to checkout from")),
1773                 OPT_BOOL('S', "staged", &opts.checkout_index,
1774                            N_("restore the index")),
1775                 OPT_BOOL('W', "worktree", &opts.checkout_worktree,
1776                            N_("restore the working tree (default)")),
1777                 OPT_BOOL(0, "ignore-unmerged", &opts.ignore_unmerged,
1778                          N_("ignore unmerged entries")),
1779                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
1780                 OPT_END()
1781         };
1782         int ret;
1783
1784         memset(&opts, 0, sizeof(opts));
1785         opts.accept_ref = 0;
1786         opts.accept_pathspec = 1;
1787         opts.empty_pathspec_ok = 0;
1788         opts.overlay_mode = 0;
1789         opts.checkout_index = -1;    /* default off */
1790         opts.checkout_worktree = -2; /* default on */
1791         opts.ignore_unmerged_opt = "--ignore-unmerged";
1792
1793         options = parse_options_dup(restore_options);
1794         options = add_common_options(&opts, options);
1795         options = add_checkout_path_options(&opts, options);
1796
1797         ret = checkout_main(argc, argv, prefix, &opts,
1798                             options, restore_usage);
1799         FREE_AND_NULL(options);
1800         return ret;
1801 }