git.oblomov.eu Git - git/blob - 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                     !ce_intent_to_add(old) &&
 130                     oideq(&ce->oid, &old->oid)) {
 131                         old->ce_flags |= CE_UPDATE;
 132                         discard_cache_entry(ce);
 133                         return 0;
 134                 }
 135         }
 136
 137         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 138         return 0;
 139 }
 140
 141 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 142 {
 143         read_tree_recursive(the_repository, tree, "", 0, 0,
 144                             pathspec, update_some, NULL);
 145
 146         /* update the index with the given tree's info
 147          * for all args, expanding wildcards, and exit
 148          * with any non-zero return code.
 149          */
 150         return 0;
 151 }
 152
 153 static int skip_same_name(const struct cache_entry *ce, int pos)
 154 {
 155         while (++pos < active_nr &&
 156                !strcmp(active_cache[pos]->name, ce->name))
 157                 ; /* skip */
 158         return pos;
 159 }
 160
 161 static int check_stage(int stage, const struct cache_entry *ce, int pos,
 162                        int overlay_mode)
 163 {
 164         while (pos < active_nr &&
 165                !strcmp(active_cache[pos]->name, ce->name)) {
 166                 if (ce_stage(active_cache[pos]) == stage)
 167                         return 0;
 168                 pos++;
 169         }
 170         if (!overlay_mode)
 171                 return 0;
 172         if (stage == 2)
 173                 return error(_("path '%s' does not have our version"), ce->name);
 174         else
 175                 return error(_("path '%s' does not have their version"), ce->name);
 176 }
 177
 178 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 179 {
 180         unsigned seen = 0;
 181         const char *name = ce->name;
 182
 183         while (pos < active_nr) {
 184                 ce = active_cache[pos];
 185                 if (strcmp(name, ce->name))
 186                         break;
 187                 seen |= (1 << ce_stage(ce));
 188                 pos++;
 189         }
 190         if ((stages & seen) != stages)
 191                 return error(_("path '%s' does not have all necessary versions"),
 192                              name);
 193         return 0;
 194 }
 195
 196 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 197                           const struct checkout *state, int *nr_checkouts,
 198                           int overlay_mode)
 199 {
 200         while (pos < active_nr &&
 201                !strcmp(active_cache[pos]->name, ce->name)) {
 202                 if (ce_stage(active_cache[pos]) == stage)
 203                         return checkout_entry(active_cache[pos], state,
 204                                               NULL, nr_checkouts);
 205                 pos++;
 206         }
 207         if (!overlay_mode) {
 208                 unlink_entry(ce);
 209                 return 0;
 210         }
 211         if (stage == 2)
 212                 return error(_("path '%s' does not have our version"), ce->name);
 213         else
 214                 return error(_("path '%s' does not have their version"), ce->name);
 215 }
 216
 217 static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
 218 {
 219         struct cache_entry *ce = active_cache[pos];
 220         const char *path = ce->name;
 221         mmfile_t ancestor, ours, theirs;
 222         int status;
 223         struct object_id oid;
 224         mmbuffer_t result_buf;
 225         struct object_id threeway[3];
 226         unsigned mode = 0;
 227
 228         memset(threeway, 0, sizeof(threeway));
 229         while (pos < active_nr) {
 230                 int stage;
 231                 stage = ce_stage(ce);
 232                 if (!stage || strcmp(path, ce->name))
 233                         break;
 234                 oidcpy(&threeway[stage - 1], &ce->oid);
 235                 if (stage == 2)
 236                         mode = create_ce_mode(ce->ce_mode);
 237                 pos++;
 238                 ce = active_cache[pos];
 239         }
 240         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 241                 return error(_("path '%s' does not have necessary versions"), path);
 242
 243         read_mmblob(&ancestor, &threeway[0]);
 244         read_mmblob(&ours, &threeway[1]);
 245         read_mmblob(&theirs, &threeway[2]);
 246
 247         /*
 248          * NEEDSWORK: re-create conflicts from merges with
 249          * merge.renormalize set, too
 250          */
 251         status = ll_merge(&result_buf, path, &ancestor, "base",
 252                           &ours, "ours", &theirs, "theirs",
 253                           state->istate, NULL);
 254         free(ancestor.ptr);
 255         free(ours.ptr);
 256         free(theirs.ptr);
 257         if (status < 0 || !result_buf.ptr) {
 258                 free(result_buf.ptr);
 259                 return error(_("path '%s': cannot merge"), path);
 260         }
 261
 262         /*
 263          * NEEDSWORK:
 264          * There is absolutely no reason to write this as a blob object
 265          * and create a phony cache entry.  This hack is primarily to get
 266          * to the write_entry() machinery that massages the contents to
 267          * work-tree format and writes out which only allows it for a
 268          * cache entry.  The code in write_entry() needs to be refactored
 269          * to allow us to feed a <buffer, size, mode> instead of a cache
 270          * entry.  Such a refactoring would help merge_recursive as well
 271          * (it also writes the merge result to the object database even
 272          * when it may contain conflicts).
 273          */
 274         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 275                 die(_("Unable to add merge result for '%s'"), path);
 276         free(result_buf.ptr);
 277         ce = make_transient_cache_entry(mode, &oid, path, 2);
 278         if (!ce)
 279                 die(_("make_cache_entry failed for path '%s'"), path);
 280         status = checkout_entry(ce, state, NULL, nr_checkouts);
 281         discard_cache_entry(ce);
 282         return status;
 283 }
 284
 285 static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
 286                                          char *ps_matched,
 287                                          const struct checkout_opts *opts)
 288 {
 289         ce->ce_flags &= ~CE_MATCHED;
 290         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 291                 return;
 292         if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 293                 /*
 294                  * "git checkout tree-ish -- path", but this entry
 295                  * is in the original index but is not in tree-ish
 296                  * or does not match the pathspec; it will not be
 297                  * checked out to the working tree.  We will not do
 298                  * anything to this entry at all.
 299                  */
 300                 return;
 301         /*
 302          * Either this entry came from the tree-ish we are
 303          * checking the paths out of, or we are checking out
 304          * of the index.
 305          *
 306          * If it comes from the tree-ish, we already know it
 307          * matches the pathspec and could just stamp
 308          * CE_MATCHED to it from update_some(). But we still
 309          * need ps_matched and read_tree_recursive (and
 310          * eventually tree_entry_interesting) cannot fill
 311          * ps_matched yet. Once it can, we can avoid calling
 312          * match_pathspec() for _all_ entries when
 313          * opts->source_tree != NULL.
 314          */
 315         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 316                 ce->ce_flags |= CE_MATCHED;
 317 }
 318
 319 static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
 320                                             char *ps_matched,
 321                                             const struct checkout_opts *opts)
 322 {
 323         ce->ce_flags &= ~CE_MATCHED;
 324         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 325                 return;
 326         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
 327                 ce->ce_flags |= CE_MATCHED;
 328                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 329                         /*
 330                          * In overlay mode, but the path is not in
 331                          * tree-ish, which means we should remove it
 332                          * from the index and the working tree.
 333                          */
 334                         ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
 335         }
 336 }
 337
 338 static int checkout_worktree(const struct checkout_opts *opts)
 339 {
 340         struct checkout state = CHECKOUT_INIT;
 341         int nr_checkouts = 0, nr_unmerged = 0;
 342         int errs = 0;
 343         int pos;
 344
 345         state.force = 1;
 346         state.refresh_cache = 1;
 347         state.istate = &the_index;
 348
 349         enable_delayed_checkout(&state);
 350         for (pos = 0; pos < active_nr; pos++) {
 351                 struct cache_entry *ce = active_cache[pos];
 352                 if (ce->ce_flags & CE_MATCHED) {
 353                         if (!ce_stage(ce)) {
 354                                 errs |= checkout_entry(ce, &state,
 355                                                        NULL, &nr_checkouts);
 356                                 continue;
 357                         }
 358                         if (opts->writeout_stage)
 359                                 errs |= checkout_stage(opts->writeout_stage,
 360                                                        ce, pos,
 361                                                        &state,
 362                                                        &nr_checkouts, opts->overlay_mode);
 363                         else if (opts->merge)
 364                                 errs |= checkout_merged(pos, &state,
 365                                                         &nr_unmerged);
 366                         pos = skip_same_name(ce, pos) - 1;
 367                 }
 368         }
 369         remove_marked_cache_entries(&the_index, 1);
 370         remove_scheduled_dirs();
 371         errs |= finish_delayed_checkout(&state, &nr_checkouts);
 372
 373         if (opts->count_checkout_paths) {
 374                 if (nr_unmerged)
 375                         fprintf_ln(stderr, Q_("Recreated %d merge conflict",
 376                                               "Recreated %d merge conflicts",
 377                                               nr_unmerged),
 378                                    nr_unmerged);
 379                 if (opts->source_tree)
 380                         fprintf_ln(stderr, Q_("Updated %d path from %s",
 381                                               "Updated %d paths from %s",
 382                                               nr_checkouts),
 383                                    nr_checkouts,
 384                                    find_unique_abbrev(&opts->source_tree->object.oid,
 385                                                       DEFAULT_ABBREV));
 386                 else if (!nr_unmerged || nr_checkouts)
 387                         fprintf_ln(stderr, Q_("Updated %d path from the index",
 388                                               "Updated %d paths from the index",
 389                                               nr_checkouts),
 390                                    nr_checkouts);
 391         }
 392
 393         return errs;
 394 }
 395
 396 static int checkout_paths(const struct checkout_opts *opts,
 397                           const char *revision)
 398 {
 399         int pos;
 400         static char *ps_matched;
 401         struct object_id rev;
 402         struct commit *head;
 403         int errs = 0;
 404         struct lock_file lock_file = LOCK_INIT;
 405         int checkout_index;
 406
 407         trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
 408
 409         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 410                 die(_("'%s' cannot be used with updating paths"), "--track");
 411
 412         if (opts->new_branch_log)
 413                 die(_("'%s' cannot be used with updating paths"), "-l");
 414
 415         if (opts->ignore_unmerged && opts->patch_mode)
 416                 die(_("'%s' cannot be used with updating paths"),
 417                     opts->ignore_unmerged_opt);
 418
 419         if (opts->force_detach)
 420                 die(_("'%s' cannot be used with updating paths"), "--detach");
 421
 422         if (opts->merge && opts->patch_mode)
 423                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 424
 425         if (opts->ignore_unmerged && opts->merge)
 426                 die(_("'%s' cannot be used with %s"),
 427                     opts->ignore_unmerged_opt, "-m");
 428
 429         if (opts->new_branch)
 430                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 431                     opts->new_branch);
 432
 433         if (!opts->checkout_worktree && !opts->checkout_index)
 434                 die(_("neither '%s' or '%s' is specified"),
 435                     "--staged", "--worktree");
 436
 437         if (!opts->checkout_worktree && !opts->from_treeish)
 438                 die(_("'%s' must be used when '%s' is not specified"),
 439                     "--worktree", "--source");
 440
 441         if (opts->checkout_index && !opts->checkout_worktree &&
 442             opts->writeout_stage)
 443                 die(_("'%s' or '%s' cannot be used with %s"),
 444                     "--ours", "--theirs", "--staged");
 445
 446         if (opts->checkout_index && !opts->checkout_worktree &&
 447             opts->merge)
 448                 die(_("'%s' or '%s' cannot be used with %s"),
 449                     "--merge", "--conflict", "--staged");
 450
 451         if (opts->patch_mode) {
 452                 const char *patch_mode;
 453
 454                 if (opts->checkout_index && opts->checkout_worktree)
 455                         patch_mode = "--patch=checkout";
 456                 else if (opts->checkout_index && !opts->checkout_worktree)
 457                         patch_mode = "--patch=reset";
 458                 else if (!opts->checkout_index && opts->checkout_worktree)
 459                         patch_mode = "--patch=worktree";
 460                 else
 461                         BUG("either flag must have been set, worktree=%d, index=%d",
 462                             opts->checkout_worktree, opts->checkout_index);
 463                 return run_add_interactive(revision, patch_mode, &opts->pathspec);
 464         }
 465
 466         repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 467         if (read_cache_preload(&opts->pathspec) < 0)
 468                 return error(_("index file corrupt"));
 469
 470         if (opts->source_tree)
 471                 read_tree_some(opts->source_tree, &opts->pathspec);
 472
 473         ps_matched = xcalloc(opts->pathspec.nr, 1);
 474
 475         /*
 476          * Make sure all pathspecs participated in locating the paths
 477          * to be checked out.
 478          */
 479         for (pos = 0; pos < active_nr; pos++)
 480                 if (opts->overlay_mode)
 481                         mark_ce_for_checkout_overlay(active_cache[pos],
 482                                                      ps_matched,
 483                                                      opts);
 484                 else
 485                         mark_ce_for_checkout_no_overlay(active_cache[pos],
 486                                                         ps_matched,
 487                                                         opts);
 488
 489         if (report_path_error(ps_matched, &opts->pathspec)) {
 490                 free(ps_matched);
 491                 return 1;
 492         }
 493         free(ps_matched);
 494
 495         /* "checkout -m path" to recreate conflicted state */
 496         if (opts->merge)
 497                 unmerge_marked_index(&the_index);
 498
 499         /* Any unmerged paths? */
 500         for (pos = 0; pos < active_nr; pos++) {
 501                 const struct cache_entry *ce = active_cache[pos];
 502                 if (ce->ce_flags & CE_MATCHED) {
 503                         if (!ce_stage(ce))
 504                                 continue;
 505                         if (opts->ignore_unmerged) {
 506                                 if (!opts->quiet)
 507                                         warning(_("path '%s' is unmerged"), ce->name);
 508                         } else if (opts->writeout_stage) {
 509                                 errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
 510                         } else if (opts->merge) {
 511                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 512                         } else {
 513                                 errs = 1;
 514                                 error(_("path '%s' is unmerged"), ce->name);
 515                         }
 516                         pos = skip_same_name(ce, pos) - 1;
 517                 }
 518         }
 519         if (errs)
 520                 return 1;
 521
 522         /* Now we are committed to check them out */
 523         if (opts->checkout_worktree)
 524                 errs |= checkout_worktree(opts);
 525
 526         /*
 527          * Allow updating the index when checking out from the index.
 528          * This is to save new stat info.
 529          */
 530         if (opts->checkout_worktree && !opts->checkout_index && !opts->source_tree)
 531                 checkout_index = 1;
 532         else
 533                 checkout_index = opts->checkout_index;
 534
 535         if (checkout_index) {
 536                 if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 537                         die(_("unable to write new index file"));
 538         } else {
 539                 /*
 540                  * NEEDSWORK: if --worktree is not specified, we
 541                  * should save stat info of checked out files in the
 542                  * index to avoid the next (potentially costly)
 543                  * refresh. But it's a bit tricker to do...
 544                  */
 545                 rollback_lock_file(&lock_file);
 546         }
 547
 548         read_ref_full("HEAD", 0, &rev, NULL);
 549         head = lookup_commit_reference_gently(the_repository, &rev, 1);
 550
 551         errs |= post_checkout_hook(head, head, 0);
 552         return errs;
 553 }
 554
 555 static void show_local_changes(struct object *head,
 556                                const struct diff_options *opts)
 557 {
 558         struct rev_info rev;
 559         /* I think we want full paths, even if we're in a subdirectory. */
 560         repo_init_revisions(the_repository, &rev, NULL);
 561         rev.diffopt.flags = opts->flags;
 562         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 563         diff_setup_done(&rev.diffopt);
 564         add_pending_object(&rev, head, NULL);
 565         run_diff_index(&rev, 0);
 566 }
 567
 568 static void describe_detached_head(const char *msg, struct commit *commit)
 569 {
 570         struct strbuf sb = STRBUF_INIT;
 571
 572         if (!parse_commit(commit))
 573                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 574         if (print_sha1_ellipsis()) {
 575                 fprintf(stderr, "%s %s... %s\n", msg,
 576                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 577         } else {
 578                 fprintf(stderr, "%s %s %s\n", msg,
 579                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 580         }
 581         strbuf_release(&sb);
 582 }
 583
 584 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 585                       int worktree, int *writeout_error)
 586 {
 587         struct unpack_trees_options opts;
 588         struct tree_desc tree_desc;
 589
 590         memset(&opts, 0, sizeof(opts));
 591         opts.head_idx = -1;
 592         opts.update = worktree;
 593         opts.skip_unmerged = !worktree;
 594         opts.reset = 1;
 595         opts.merge = 1;
 596         opts.fn = oneway_merge;
 597         opts.verbose_update = o->show_progress;
 598         opts.src_index = &the_index;
 599         opts.dst_index = &the_index;
 600         parse_tree(tree);
 601         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 602         switch (unpack_trees(1, &tree_desc, &opts)) {
 603         case -2:
 604                 *writeout_error = 1;
 605                 /*
 606                  * We return 0 nevertheless, as the index is all right
 607                  * and more importantly we have made best efforts to
 608                  * update paths in the work tree, and we cannot revert
 609                  * them.
 610                  */
 611                 /* fallthrough */
 612         case 0:
 613                 return 0;
 614         default:
 615                 return 128;
 616         }
 617 }
 618
 619 struct branch_info {
 620         const char *name; /* The short name used */
 621         const char *path; /* The full name of a real branch */
 622         struct commit *commit; /* The named commit */
 623         /*
 624          * if not null the branch is detached because it's already
 625          * checked out in this checkout
 626          */
 627         char *checkout;
 628 };
 629
 630 static void setup_branch_path(struct branch_info *branch)
 631 {
 632         struct strbuf buf = STRBUF_INIT;
 633
 634         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 635         if (strcmp(buf.buf, branch->name))
 636                 branch->name = xstrdup(buf.buf);
 637         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 638         branch->path = strbuf_detach(&buf, NULL);
 639 }
 640
 641 static int merge_working_tree(const struct checkout_opts *opts,
 642                               struct branch_info *old_branch_info,
 643                               struct branch_info *new_branch_info,
 644                               int *writeout_error)
 645 {
 646         int ret;
 647         struct lock_file lock_file = LOCK_INIT;
 648         struct tree *new_tree;
 649
 650         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 651         if (read_cache_preload(NULL) < 0)
 652                 return error(_("index file corrupt"));
 653
 654         resolve_undo_clear();
 655         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 656                 if (new_branch_info->commit)
 657                         BUG("'switch --orphan' should never accept a commit as starting point");
 658                 new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
 659         } else
 660                 new_tree = get_commit_tree(new_branch_info->commit);
 661         if (opts->discard_changes) {
 662                 ret = reset_tree(new_tree, opts, 1, writeout_error);
 663                 if (ret)
 664                         return ret;
 665         } else {
 666                 struct tree_desc trees[2];
 667                 struct tree *tree;
 668                 struct unpack_trees_options topts;
 669
 670                 memset(&topts, 0, sizeof(topts));
 671                 topts.head_idx = -1;
 672                 topts.src_index = &the_index;
 673                 topts.dst_index = &the_index;
 674
 675                 setup_unpack_trees_porcelain(&topts, "checkout");
 676
 677                 refresh_cache(REFRESH_QUIET);
 678
 679                 if (unmerged_cache()) {
 680                         error(_("you need to resolve your current index first"));
 681                         return 1;
 682                 }
 683
 684                 /* 2-way merge to the new branch */
 685                 topts.initial_checkout = is_cache_unborn();
 686                 topts.update = 1;
 687                 topts.merge = 1;
 688                 topts.quiet = opts->merge && old_branch_info->commit;
 689                 topts.verbose_update = opts->show_progress;
 690                 topts.fn = twoway_merge;
 691                 if (opts->overwrite_ignore) {
 692                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 693                         topts.dir->flags |= DIR_SHOW_IGNORED;
 694                         setup_standard_excludes(topts.dir);
 695                 }
 696                 tree = parse_tree_indirect(old_branch_info->commit ?
 697                                            &old_branch_info->commit->object.oid :
 698                                            the_hash_algo->empty_tree);
 699                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 700                 parse_tree(new_tree);
 701                 tree = new_tree;
 702                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 703
 704                 ret = unpack_trees(2, trees, &topts);
 705                 clear_unpack_trees_porcelain(&topts);
 706                 if (ret == -1) {
 707                         /*
 708                          * Unpack couldn't do a trivial merge; either
 709                          * give up or do a real merge, depending on
 710                          * whether the merge flag was used.
 711                          */
 712                         struct tree *result;
 713                         struct tree *work;
 714                         struct tree *old_tree;
 715                         struct merge_options o;
 716                         struct strbuf sb = STRBUF_INIT;
 717
 718                         if (!opts->merge)
 719                                 return 1;
 720
 721                         /*
 722                          * Without old_branch_info->commit, the below is the same as
 723                          * the two-tree unpack we already tried and failed.
 724                          */
 725                         if (!old_branch_info->commit)
 726                                 return 1;
 727                         old_tree = get_commit_tree(old_branch_info->commit);
 728
 729                         if (repo_index_has_changes(the_repository, old_tree, &sb))
 730                                 die(_("cannot continue with staged changes in "
 731                                       "the following files:\n%s"), sb.buf);
 732                         strbuf_release(&sb);
 733
 734                         /* Do more real merge */
 735
 736                         /*
 737                          * We update the index fully, then write the
 738                          * tree from the index, then merge the new
 739                          * branch with the current tree, with the old
 740                          * branch as the base. Then we reset the index
 741                          * (but not the working tree) to the new
 742                          * branch, leaving the working tree as the
 743                          * merged version, but skipping unmerged
 744                          * entries in the index.
 745                          */
 746
 747                         add_files_to_cache(NULL, NULL, 0);
 748                         /*
 749                          * NEEDSWORK: carrying over local changes
 750                          * when branches have different end-of-line
 751                          * normalization (or clean+smudge rules) is
 752                          * a pain; plumb in an option to set
 753                          * o.renormalize?
 754                          */
 755                         init_merge_options(&o, the_repository);
 756                         o.verbosity = 0;
 757                         work = write_tree_from_memory(&o);
 758
 759                         ret = reset_tree(new_tree,
 760                                          opts, 1,
 761                                          writeout_error);
 762                         if (ret)
 763                                 return ret;
 764                         o.ancestor = old_branch_info->name;
 765                         o.branch1 = new_branch_info->name;
 766                         o.branch2 = "local";
 767                         ret = merge_trees(&o,
 768                                           new_tree,
 769                                           work,
 770                                           old_tree,
 771                                           &result);
 772                         if (ret < 0)
 773                                 exit(128);
 774                         ret = reset_tree(new_tree,
 775                                          opts, 0,
 776                                          writeout_error);
 777                         strbuf_release(&o.obuf);
 778                         if (ret)
 779                                 return ret;
 780                 }
 781         }
 782
 783         if (!active_cache_tree)
 784                 active_cache_tree = cache_tree();
 785
 786         if (!cache_tree_fully_valid(active_cache_tree))
 787                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 788
 789         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 790                 die(_("unable to write new index file"));
 791
 792         if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
 793                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 794
 795         return 0;
 796 }
 797
 798 static void report_tracking(struct branch_info *new_branch_info)
 799 {
 800         struct strbuf sb = STRBUF_INIT;
 801         struct branch *branch = branch_get(new_branch_info->name);
 802
 803         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 804                 return;
 805         fputs(sb.buf, stdout);
 806         strbuf_release(&sb);
 807 }
 808
 809 static void update_refs_for_switch(const struct checkout_opts *opts,
 810                                    struct branch_info *old_branch_info,
 811                                    struct branch_info *new_branch_info)
 812 {
 813         struct strbuf msg = STRBUF_INIT;
 814         const char *old_desc, *reflog_msg;
 815         if (opts->new_branch) {
 816                 if (opts->new_orphan_branch) {
 817                         char *refname;
 818
 819                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 820                         if (opts->new_branch_log &&
 821                             !should_autocreate_reflog(refname)) {
 822                                 int ret;
 823                                 struct strbuf err = STRBUF_INIT;
 824
 825                                 ret = safe_create_reflog(refname, 1, &err);
 826                                 if (ret) {
 827                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 828                                                 opts->new_orphan_branch, err.buf);
 829                                         strbuf_release(&err);
 830                                         free(refname);
 831                                         return;
 832                                 }
 833                                 strbuf_release(&err);
 834                         }
 835                         free(refname);
 836                 }
 837                 else
 838                         create_branch(the_repository,
 839                                       opts->new_branch, new_branch_info->name,
 840                                       opts->new_branch_force ? 1 : 0,
 841                                       opts->new_branch_force ? 1 : 0,
 842                                       opts->new_branch_log,
 843                                       opts->quiet,
 844                                       opts->track);
 845                 new_branch_info->name = opts->new_branch;
 846                 setup_branch_path(new_branch_info);
 847         }
 848
 849         old_desc = old_branch_info->name;
 850         if (!old_desc && old_branch_info->commit)
 851                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 852
 853         reflog_msg = getenv("GIT_REFLOG_ACTION");
 854         if (!reflog_msg)
 855                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 856                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 857         else
 858                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 859
 860         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 861                 /* Nothing to do. */
 862         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 863                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 864                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 865                 if (!opts->quiet) {
 866                         if (old_branch_info->path &&
 867                             advice_detached_head && !opts->force_detach)
 868                                 detach_advice(new_branch_info->name);
 869                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 870                 }
 871         } else if (new_branch_info->path) {     /* Switch branches. */
 872                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 873                         die(_("unable to update HEAD"));
 874                 if (!opts->quiet) {
 875                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 876                                 if (opts->new_branch_force)
 877                                         fprintf(stderr, _("Reset branch '%s'\n"),
 878                                                 new_branch_info->name);
 879                                 else
 880                                         fprintf(stderr, _("Already on '%s'\n"),
 881                                                 new_branch_info->name);
 882                         } else if (opts->new_branch) {
 883                                 if (opts->branch_exists)
 884                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 885                                 else
 886                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 887                         } else {
 888                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 889                                         new_branch_info->name);
 890                         }
 891                 }
 892                 if (old_branch_info->path && old_branch_info->name) {
 893                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 894                                 delete_reflog(old_branch_info->path);
 895                 }
 896         }
 897         remove_branch_state(the_repository, !opts->quiet);
 898         strbuf_release(&msg);
 899         if (!opts->quiet &&
 900             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 901                 report_tracking(new_branch_info);
 902 }
 903
 904 static int add_pending_uninteresting_ref(const char *refname,
 905                                          const struct object_id *oid,
 906                                          int flags, void *cb_data)
 907 {
 908         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 909         return 0;
 910 }
 911
 912 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 913 {
 914         strbuf_addstr(sb, "  ");
 915         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 916         strbuf_addch(sb, ' ');
 917         if (!parse_commit(commit))
 918                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 919         strbuf_addch(sb, '\n');
 920 }
 921
 922 #define ORPHAN_CUTOFF 4
 923 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 924 {
 925         struct commit *c, *last = NULL;
 926         struct strbuf sb = STRBUF_INIT;
 927         int lost = 0;
 928         while ((c = get_revision(revs)) != NULL) {
 929                 if (lost < ORPHAN_CUTOFF)
 930                         describe_one_orphan(&sb, c);
 931                 last = c;
 932                 lost++;
 933         }
 934         if (ORPHAN_CUTOFF < lost) {
 935                 int more = lost - ORPHAN_CUTOFF;
 936                 if (more == 1)
 937                         describe_one_orphan(&sb, last);
 938                 else
 939                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 940         }
 941
 942         fprintf(stderr,
 943                 Q_(
 944                 /* The singular version */
 945                 "Warning: you are leaving %d commit behind, "
 946                 "not connected to\n"
 947                 "any of your branches:\n\n"
 948                 "%s\n",
 949                 /* The plural version */
 950                 "Warning: you are leaving %d commits behind, "
 951                 "not connected to\n"
 952                 "any of your branches:\n\n"
 953                 "%s\n",
 954                 /* Give ngettext() the count */
 955                 lost),
 956                 lost,
 957                 sb.buf);
 958         strbuf_release(&sb);
 959
 960         if (advice_detached_head)
 961                 fprintf(stderr,
 962                         Q_(
 963                         /* The singular version */
 964                         "If you want to keep it by creating a new branch, "
 965                         "this may be a good time\nto do so with:\n\n"
 966                         " git branch <new-branch-name> %s\n\n",
 967                         /* The plural version */
 968                         "If you want to keep them by creating a new branch, "
 969                         "this may be a good time\nto do so with:\n\n"
 970                         " git branch <new-branch-name> %s\n\n",
 971                         /* Give ngettext() the count */
 972                         lost),
 973                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 974 }
 975
 976 /*
 977  * We are about to leave commit that was at the tip of a detached
 978  * HEAD.  If it is not reachable from any ref, this is the last chance
 979  * for the user to do so without resorting to reflog.
 980  */
 981 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 982 {
 983         struct rev_info revs;
 984         struct object *object = &old_commit->object;
 985
 986         repo_init_revisions(the_repository, &revs, NULL);
 987         setup_revisions(0, NULL, &revs, NULL);
 988
 989         object->flags &= ~UNINTERESTING;
 990         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 991
 992         for_each_ref(add_pending_uninteresting_ref, &revs);
 993         if (new_commit)
 994                 add_pending_oid(&revs, "HEAD",
 995                                 &new_commit->object.oid,
 996                                 UNINTERESTING);
 997
 998         if (prepare_revision_walk(&revs))
 999                 die(_("internal error in revision walk"));
1000         if (!(old_commit->object.flags & UNINTERESTING))
1001                 suggest_reattach(old_commit, &revs);
1002         else
1003                 describe_detached_head(_("Previous HEAD position was"), old_commit);
1004
1005         /* Clean up objects used, as they will be reused. */
1006         clear_commit_marks_all(ALL_REV_FLAGS);
1007 }
1008
1009 static int switch_branches(const struct checkout_opts *opts,
1010                            struct branch_info *new_branch_info)
1011 {
1012         int ret = 0;
1013         struct branch_info old_branch_info;
1014         void *path_to_free;
1015         struct object_id rev;
1016         int flag, writeout_error = 0;
1017         int do_merge = 1;
1018
1019         trace2_cmd_mode("branch");
1020
1021         memset(&old_branch_info, 0, sizeof(old_branch_info));
1022         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1023         if (old_branch_info.path)
1024                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1025         if (!(flag & REF_ISSYMREF))
1026                 old_branch_info.path = NULL;
1027
1028         if (old_branch_info.path)
1029                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1030
1031         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
1032                 if (new_branch_info->name)
1033                         BUG("'switch --orphan' should never accept a commit as starting point");
1034                 new_branch_info->commit = NULL;
1035                 new_branch_info->name = "(empty)";
1036                 do_merge = 1;
1037         }
1038
1039         if (!new_branch_info->name) {
1040                 new_branch_info->name = "HEAD";
1041                 new_branch_info->commit = old_branch_info.commit;
1042                 if (!new_branch_info->commit)
1043                         die(_("You are on a branch yet to be born"));
1044                 parse_commit_or_die(new_branch_info->commit);
1045
1046                 if (opts->only_merge_on_switching_branches)
1047                         do_merge = 0;
1048         }
1049
1050         if (do_merge) {
1051                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1052                 if (ret) {
1053                         free(path_to_free);
1054                         return ret;
1055                 }
1056         }
1057
1058         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1059                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1060
1061         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1062
1063         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1064         free(path_to_free);
1065         return ret || writeout_error;
1066 }
1067
1068 static int git_checkout_config(const char *var, const char *value, void *cb)
1069 {
1070         if (!strcmp(var, "diff.ignoresubmodules")) {
1071                 struct checkout_opts *opts = cb;
1072                 handle_ignore_submodules_arg(&opts->diff_options, value);
1073                 return 0;
1074         }
1075
1076         if (starts_with(var, "submodule."))
1077                 return git_default_submodule_config(var, value, NULL);
1078
1079         return git_xmerge_config(var, value, NULL);
1080 }
1081
1082 static void setup_new_branch_info_and_source_tree(
1083         struct branch_info *new_branch_info,
1084         struct checkout_opts *opts,
1085         struct object_id *rev,
1086         const char *arg)
1087 {
1088         struct tree **source_tree = &opts->source_tree;
1089         struct object_id branch_rev;
1090
1091         new_branch_info->name = arg;
1092         setup_branch_path(new_branch_info);
1093
1094         if (!check_refname_format(new_branch_info->path, 0) &&
1095             !read_ref(new_branch_info->path, &branch_rev))
1096                 oidcpy(rev, &branch_rev);
1097         else
1098                 new_branch_info->path = NULL; /* not an existing branch */
1099
1100         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1101         if (!new_branch_info->commit) {
1102                 /* not a commit */
1103                 *source_tree = parse_tree_indirect(rev);
1104         } else {
1105                 parse_commit_or_die(new_branch_info->commit);
1106                 *source_tree = get_commit_tree(new_branch_info->commit);
1107         }
1108 }
1109
1110 static int parse_branchname_arg(int argc, const char **argv,
1111                                 int dwim_new_local_branch_ok,
1112                                 struct branch_info *new_branch_info,
1113                                 struct checkout_opts *opts,
1114                                 struct object_id *rev,
1115                                 int *dwim_remotes_matched)
1116 {
1117         const char **new_branch = &opts->new_branch;
1118         int argcount = 0;
1119         const char *arg;
1120         int dash_dash_pos;
1121         int has_dash_dash = 0;
1122         int i;
1123
1124         /*
1125          * case 1: git checkout <ref> -- [<paths>]
1126          *
1127          *   <ref> must be a valid tree, everything after the '--' must be
1128          *   a path.
1129          *
1130          * case 2: git checkout -- [<paths>]
1131          *
1132          *   everything after the '--' must be paths.
1133          *
1134          * case 3: git checkout <something> [--]
1135          *
1136          *   (a) If <something> is a commit, that is to
1137          *       switch to the branch or detach HEAD at it.  As a special case,
1138          *       if <something> is A...B (missing A or B means HEAD but you can
1139          *       omit at most one side), and if there is a unique merge base
1140          *       between A and B, A...B names that merge base.
1141          *
1142          *   (b) If <something> is _not_ a commit, either "--" is present
1143          *       or <something> is not a path, no -t or -b was given, and
1144          *       and there is a tracking branch whose name is <something>
1145          *       in one and only one remote (or if the branch exists on the
1146          *       remote named in checkout.defaultRemote), then this is a
1147          *       short-hand to fork local <something> from that
1148          *       remote-tracking branch.
1149          *
1150          *   (c) Otherwise, if "--" is present, treat it like case (1).
1151          *
1152          *   (d) Otherwise :
1153          *       - if it's a reference, treat it like case (1)
1154          *       - else if it's a path, treat it like case (2)
1155          *       - else: fail.
1156          *
1157          * case 4: git checkout <something> <paths>
1158          *
1159          *   The first argument must not be ambiguous.
1160          *   - If it's *only* a reference, treat it like case (1).
1161          *   - If it's only a path, treat it like case (2).
1162          *   - else: fail.
1163          *
1164          */
1165         if (!argc)
1166                 return 0;
1167
1168         if (!opts->accept_pathspec) {
1169                 if (argc > 1)
1170                         die(_("only one reference expected"));
1171                 has_dash_dash = 1; /* helps disambiguate */
1172         }
1173
1174         arg = argv[0];
1175         dash_dash_pos = -1;
1176         for (i = 0; i < argc; i++) {
1177                 if (opts->accept_pathspec && !strcmp(argv[i], "--")) {
1178                         dash_dash_pos = i;
1179                         break;
1180                 }
1181         }
1182         if (dash_dash_pos == 0)
1183                 return 1; /* case (2) */
1184         else if (dash_dash_pos == 1)
1185                 has_dash_dash = 1; /* case (3) or (1) */
1186         else if (dash_dash_pos >= 2)
1187                 die(_("only one reference expected, %d given."), dash_dash_pos);
1188         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1189
1190         if (!strcmp(arg, "-"))
1191                 arg = "@{-1}";
1192
1193         if (get_oid_mb(arg, rev)) {
1194                 /*
1195                  * Either case (3) or (4), with <something> not being
1196                  * a commit, or an attempt to use case (1) with an
1197                  * invalid ref.
1198                  *
1199                  * It's likely an error, but we need to find out if
1200                  * we should auto-create the branch, case (3).(b).
1201                  */
1202                 int recover_with_dwim = dwim_new_local_branch_ok;
1203
1204                 int could_be_checkout_paths = !has_dash_dash &&
1205                         check_filename(opts->prefix, arg);
1206
1207                 if (!has_dash_dash && !no_wildcard(arg))
1208                         recover_with_dwim = 0;
1209
1210                 /*
1211                  * Accept "git checkout foo", "git checkout foo --"
1212                  * and "git switch foo" as candidates for dwim.
1213                  */
1214                 if (!(argc == 1 && !has_dash_dash) &&
1215                     !(argc == 2 && has_dash_dash) &&
1216                     opts->accept_pathspec)
1217                         recover_with_dwim = 0;
1218
1219                 if (recover_with_dwim) {
1220                         const char *remote = unique_tracking_name(arg, rev,
1221                                                                   dwim_remotes_matched);
1222                         if (remote) {
1223                                 if (could_be_checkout_paths)
1224                                         die(_("'%s' could be both a local file and a tracking branch.\n"
1225                                               "Please use -- (and optionally --no-guess) to disambiguate"),
1226                                             arg);
1227                                 *new_branch = arg;
1228                                 arg = remote;
1229                                 /* DWIMmed to create local branch, case (3).(b) */
1230                         } else {
1231                                 recover_with_dwim = 0;
1232                         }
1233                 }
1234
1235                 if (!recover_with_dwim) {
1236                         if (has_dash_dash)
1237                                 die(_("invalid reference: %s"), arg);
1238                         return argcount;
1239                 }
1240         }
1241
1242         /* we can't end up being in (2) anymore, eat the argument */
1243         argcount++;
1244         argv++;
1245         argc--;
1246
1247         setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1248
1249         if (!opts->source_tree)                   /* case (1): want a tree */
1250                 die(_("reference is not a tree: %s"), arg);
1251
1252         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1253                 /*
1254                  * Do not complain the most common case
1255                  *      git checkout branch
1256                  * even if there happen to be a file called 'branch';
1257                  * it would be extremely annoying.
1258                  */
1259                 if (argc)
1260                         verify_non_filename(opts->prefix, arg);
1261         } else if (opts->accept_pathspec) {
1262                 argcount++;
1263                 argv++;
1264                 argc--;
1265         }
1266
1267         return argcount;
1268 }
1269
1270 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1271 {
1272         int status;
1273         struct strbuf branch_ref = STRBUF_INIT;
1274
1275         trace2_cmd_mode("unborn");
1276
1277         if (!opts->new_branch)
1278                 die(_("You are on a branch yet to be born"));
1279         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1280         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1281         strbuf_release(&branch_ref);
1282         if (!opts->quiet)
1283                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1284                         opts->new_branch);
1285         return status;
1286 }
1287
1288 static void die_expecting_a_branch(const struct branch_info *branch_info)
1289 {
1290         struct object_id oid;
1291         char *to_free;
1292
1293         if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free) == 1) {
1294                 const char *ref = to_free;
1295
1296                 if (skip_prefix(ref, "refs/tags/", &ref))
1297                         die(_("a branch is expected, got tag '%s'"), ref);
1298                 if (skip_prefix(ref, "refs/remotes/", &ref))
1299                         die(_("a branch is expected, got remote branch '%s'"), ref);
1300                 die(_("a branch is expected, got '%s'"), ref);
1301         }
1302         if (branch_info->commit)
1303                 die(_("a branch is expected, got commit '%s'"), branch_info->name);
1304         /*
1305          * This case should never happen because we already die() on
1306          * non-commit, but just in case.
1307          */
1308         die(_("a branch is expected, got '%s'"), branch_info->name);
1309 }
1310
1311 static void die_if_some_operation_in_progress(void)
1312 {
1313         struct wt_status_state state;
1314
1315         memset(&state, 0, sizeof(state));
1316         wt_status_get_state(the_repository, &state, 0);
1317
1318         if (state.merge_in_progress)
1319                 die(_("cannot switch branch while merging\n"
1320                       "Consider \"git merge --quit\" "
1321                       "or \"git worktree add\"."));
1322         if (state.am_in_progress)
1323                 die(_("cannot switch branch in the middle of an am session\n"
1324                       "Consider \"git am --quit\" "
1325                       "or \"git worktree add\"."));
1326         if (state.rebase_interactive_in_progress || state.rebase_in_progress)
1327                 die(_("cannot switch branch while rebasing\n"
1328                       "Consider \"git rebase --quit\" "
1329                       "or \"git worktree add\"."));
1330         if (state.cherry_pick_in_progress)
1331                 die(_("cannot switch branch while cherry-picking\n"
1332                       "Consider \"git cherry-pick --quit\" "
1333                       "or \"git worktree add\"."));
1334         if (state.revert_in_progress)
1335                 die(_("cannot switch branch while reverting\n"
1336                       "Consider \"git revert --quit\" "
1337                       "or \"git worktree add\"."));
1338         if (state.bisect_in_progress)
1339                 warning(_("you are switching branch while bisecting"));
1340 }
1341
1342 static int checkout_branch(struct checkout_opts *opts,
1343                            struct branch_info *new_branch_info)
1344 {
1345         if (opts->pathspec.nr)
1346                 die(_("paths cannot be used with switching branches"));
1347
1348         if (opts->patch_mode)
1349                 die(_("'%s' cannot be used with switching branches"),
1350                     "--patch");
1351
1352         if (opts->overlay_mode != -1)
1353                 die(_("'%s' cannot be used with switching branches"),
1354                     "--[no]-overlay");
1355
1356         if (opts->writeout_stage)
1357                 die(_("'%s' cannot be used with switching branches"),
1358                     "--ours/--theirs");
1359
1360         if (opts->force && opts->merge)
1361                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1362
1363         if (opts->discard_changes && opts->merge)
1364                 die(_("'%s' cannot be used with '%s'"), "--discard-changes", "--merge");
1365
1366         if (opts->force_detach && opts->new_branch)
1367                 die(_("'%s' cannot be used with '%s'"),
1368                     "--detach", "-b/-B/--orphan");
1369
1370         if (opts->new_orphan_branch) {
1371                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1372                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1373                 if (opts->orphan_from_empty_tree && new_branch_info->name)
1374                         die(_("'%s' cannot take <start-point>"), "--orphan");
1375         } else if (opts->force_detach) {
1376                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1377                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1378         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1379                 opts->track = git_branch_track;
1380
1381         if (new_branch_info->name && !new_branch_info->commit)
1382                 die(_("Cannot switch branch to a non-commit '%s'"),
1383                     new_branch_info->name);
1384
1385         if (!opts->switch_branch_doing_nothing_is_ok &&
1386             !new_branch_info->name &&
1387             !opts->new_branch &&
1388             !opts->force_detach)
1389                 die(_("missing branch or commit argument"));
1390
1391         if (!opts->implicit_detach &&
1392             !opts->force_detach &&
1393             !opts->new_branch &&
1394             !opts->new_branch_force &&
1395             new_branch_info->name &&
1396             !new_branch_info->path)
1397                 die_expecting_a_branch(new_branch_info);
1398
1399         if (!opts->can_switch_when_in_progress)
1400                 die_if_some_operation_in_progress();
1401
1402         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1403             !opts->ignore_other_worktrees) {
1404                 int flag;
1405                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1406                 if (head_ref &&
1407                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1408                         die_if_checked_out(new_branch_info->path, 1);
1409                 free(head_ref);
1410         }
1411
1412         if (!new_branch_info->commit && opts->new_branch) {
1413                 struct object_id rev;
1414                 int flag;
1415
1416                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1417                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1418                         return switch_unborn_to_new_branch(opts);
1419         }
1420         return switch_branches(opts, new_branch_info);
1421 }
1422
1423 static struct option *add_common_options(struct checkout_opts *opts,
1424                                          struct option *prevopts)
1425 {
1426         struct option options[] = {
1427                 OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1428                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1429                             "checkout", "control recursive updating of submodules",
1430                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1431                 OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1432                 OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1433                 OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1434                            N_("conflict style (merge or diff3)")),
1435                 OPT_END()
1436         };
1437         struct option *newopts = parse_options_concat(prevopts, options);
1438         free(prevopts);
1439         return newopts;
1440 }
1441
1442 static struct option *add_common_switch_branch_options(
1443         struct checkout_opts *opts, struct option *prevopts)
1444 {
1445         struct option options[] = {
1446                 OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1447                 OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1448                         BRANCH_TRACK_EXPLICIT),
1449                 OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1450                            PARSE_OPT_NOCOMPLETE),
1451                 OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1452                 OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1453                            N_("update ignored files (default)"),
1454                            PARSE_OPT_NOCOMPLETE),
1455                 OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1456                          N_("do not check if another worktree is holding the given ref")),
1457                 OPT_END()
1458         };
1459         struct option *newopts = parse_options_concat(prevopts, options);
1460         free(prevopts);
1461         return newopts;
1462 }
1463
1464 static struct option *add_checkout_path_options(struct checkout_opts *opts,
1465                                                 struct option *prevopts)
1466 {
1467         struct option options[] = {
1468                 OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1469                               N_("checkout our version for unmerged files"),
1470                               2, PARSE_OPT_NONEG),
1471                 OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1472                               N_("checkout their version for unmerged files"),
1473                               3, PARSE_OPT_NONEG),
1474                 OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1475                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1476                          N_("do not limit pathspecs to sparse entries only")),
1477                 OPT_END()
1478         };
1479         struct option *newopts = parse_options_concat(prevopts, options);
1480         free(prevopts);
1481         return newopts;
1482 }
1483
1484 static int checkout_main(int argc, const char **argv, const char *prefix,
1485                          struct checkout_opts *opts, struct option *options,
1486                          const char * const usagestr[])
1487 {
1488         struct branch_info new_branch_info;
1489         int dwim_remotes_matched = 0;
1490         int parseopt_flags = 0;
1491
1492         memset(&new_branch_info, 0, sizeof(new_branch_info));
1493         opts->overwrite_ignore = 1;
1494         opts->prefix = prefix;
1495         opts->show_progress = -1;
1496
1497         git_config(git_checkout_config, opts);
1498
1499         opts->track = BRANCH_TRACK_UNSPECIFIED;
1500
1501         if (!opts->accept_pathspec && !opts->accept_ref)
1502                 BUG("make up your mind, you need to take _something_");
1503         if (opts->accept_pathspec && opts->accept_ref)
1504                 parseopt_flags = PARSE_OPT_KEEP_DASHDASH;
1505
1506         argc = parse_options(argc, argv, prefix, options,
1507                              usagestr, parseopt_flags);
1508
1509         if (opts->show_progress < 0) {
1510                 if (opts->quiet)
1511                         opts->show_progress = 0;
1512                 else
1513                         opts->show_progress = isatty(2);
1514         }
1515
1516         if (opts->conflict_style) {
1517                 opts->merge = 1; /* implied */
1518                 git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1519         }
1520         if (opts->force) {
1521                 opts->discard_changes = 1;
1522                 opts->ignore_unmerged_opt = "--force";
1523                 opts->ignore_unmerged = 1;
1524         }
1525
1526         if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1527                 die(_("-b, -B and --orphan are mutually exclusive"));
1528
1529         if (opts->overlay_mode == 1 && opts->patch_mode)
1530                 die(_("-p and --overlay are mutually exclusive"));
1531
1532         if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
1533                 if (opts->checkout_index < 0)
1534                         opts->checkout_index = 0;
1535                 if (opts->checkout_worktree < 0)
1536                         opts->checkout_worktree = 0;
1537         } else {
1538                 if (opts->checkout_index < 0)
1539                         opts->checkout_index = -opts->checkout_index - 1;
1540                 if (opts->checkout_worktree < 0)
1541                         opts->checkout_worktree = -opts->checkout_worktree - 1;
1542         }
1543         if (opts->checkout_index < 0 || opts->checkout_worktree < 0)
1544                 BUG("these flags should be non-negative by now");
1545         /*
1546          * convenient shortcut: "git restore --staged" equals
1547          * "git restore --staged --source HEAD"
1548          */
1549         if (!opts->from_treeish && opts->checkout_index && !opts->checkout_worktree)
1550                 opts->from_treeish = "HEAD";
1551
1552         /*
1553          * From here on, new_branch will contain the branch to be checked out,
1554          * and new_branch_force and new_orphan_branch will tell us which one of
1555          * -b/-B/--orphan is being used.
1556          */
1557         if (opts->new_branch_force)
1558                 opts->new_branch = opts->new_branch_force;
1559
1560         if (opts->new_orphan_branch)
1561                 opts->new_branch = opts->new_orphan_branch;
1562
1563         /* --track without -b/-B/--orphan should DWIM */
1564         if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1565                 const char *argv0 = argv[0];
1566                 if (!argc || !strcmp(argv0, "--"))
1567                         die(_("--track needs a branch name"));
1568                 skip_prefix(argv0, "refs/", &argv0);
1569                 skip_prefix(argv0, "remotes/", &argv0);
1570                 argv0 = strchr(argv0, '/');
1571                 if (!argv0 || !argv0[1])
1572                         die(_("missing branch name; try -b"));
1573                 opts->new_branch = argv0 + 1;
1574         }
1575
1576         /*
1577          * Extract branch name from command line arguments, so
1578          * all that is left is pathspecs.
1579          *
1580          * Handle
1581          *
1582          *  1) git checkout <tree> -- [<paths>]
1583          *  2) git checkout -- [<paths>]
1584          *  3) git checkout <something> [<paths>]
1585          *
1586          * including "last branch" syntax and DWIM-ery for names of
1587          * remote branches, erroring out for invalid or ambiguous cases.
1588          */
1589         if (argc && opts->accept_ref) {
1590                 struct object_id rev;
1591                 int dwim_ok =
1592                         !opts->patch_mode &&
1593                         opts->dwim_new_local_branch &&
1594                         opts->track == BRANCH_TRACK_UNSPECIFIED &&
1595                         !opts->new_branch;
1596                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1597                                              &new_branch_info, opts, &rev,
1598                                              &dwim_remotes_matched);
1599                 argv += n;
1600                 argc -= n;
1601         } else if (!opts->accept_ref && opts->from_treeish) {
1602                 struct object_id rev;
1603
1604                 if (get_oid_mb(opts->from_treeish, &rev))
1605                         die(_("could not resolve %s"), opts->from_treeish);
1606
1607                 setup_new_branch_info_and_source_tree(&new_branch_info,
1608                                                       opts, &rev,
1609                                                       opts->from_treeish);
1610
1611                 if (!opts->source_tree)
1612                         die(_("reference is not a tree: %s"), opts->from_treeish);
1613         }
1614
1615         if (opts->accept_pathspec && !opts->empty_pathspec_ok && !argc &&
1616             !opts->patch_mode)  /* patch mode is special */
1617                 die(_("you must specify path(s) to restore"));
1618
1619         if (argc) {
1620                 parse_pathspec(&opts->pathspec, 0,
1621                                opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1622                                prefix, argv);
1623
1624                 if (!opts->pathspec.nr)
1625                         die(_("invalid path specification"));
1626
1627                 /*
1628                  * Try to give more helpful suggestion.
1629                  * new_branch && argc > 1 will be caught later.
1630                  */
1631                 if (opts->new_branch && argc == 1)
1632                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1633                                 argv[0], opts->new_branch);
1634
1635                 if (opts->force_detach)
1636                         die(_("git checkout: --detach does not take a path argument '%s'"),
1637                             argv[0]);
1638
1639                 if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1640                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1641                               "checking out of the index."));
1642         }
1643
1644         if (opts->new_branch) {
1645                 struct strbuf buf = STRBUF_INIT;
1646
1647                 if (opts->new_branch_force)
1648                         opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1649                 else
1650                         opts->branch_exists =
1651                                 validate_new_branchname(opts->new_branch, &buf, 0);
1652                 strbuf_release(&buf);
1653         }
1654
1655         UNLEAK(opts);
1656         if (opts->patch_mode || opts->pathspec.nr) {
1657                 int ret = checkout_paths(opts, new_branch_info.name);
1658                 if (ret && dwim_remotes_matched > 1 &&
1659                     advice_checkout_ambiguous_remote_branch_name)
1660                         advise(_("'%s' matched more than one remote tracking branch.\n"
1661                                  "We found %d remotes with a reference that matched. So we fell back\n"
1662                                  "on trying to resolve the argument as a path, but failed there too!\n"
1663                                  "\n"
1664                                  "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1665                                  "you can do so by fully qualifying the name with the --track option:\n"
1666                                  "\n"
1667                                  "    git checkout --track origin/<name>\n"
1668                                  "\n"
1669                                  "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1670                                  "one remote, e.g. the 'origin' remote, consider setting\n"
1671                                  "checkout.defaultRemote=origin in your config."),
1672                                argv[0],
1673                                dwim_remotes_matched);
1674                 return ret;
1675         } else {
1676                 return checkout_branch(opts, &new_branch_info);
1677         }
1678 }
1679
1680 int cmd_checkout(int argc, const char **argv, const char *prefix)
1681 {
1682         struct checkout_opts opts;
1683         struct option *options;
1684         struct option checkout_options[] = {
1685                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1686                            N_("create and checkout a new branch")),
1687                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1688                            N_("create/reset and checkout a branch")),
1689                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1690                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1691                          N_("second guess 'git checkout <no-such-branch>' (default)")),
1692                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1693                 OPT_END()
1694         };
1695         int ret;
1696
1697         memset(&opts, 0, sizeof(opts));
1698         opts.dwim_new_local_branch = 1;
1699         opts.switch_branch_doing_nothing_is_ok = 1;
1700         opts.only_merge_on_switching_branches = 0;
1701         opts.accept_ref = 1;
1702         opts.accept_pathspec = 1;
1703         opts.implicit_detach = 1;
1704         opts.can_switch_when_in_progress = 1;
1705         opts.orphan_from_empty_tree = 0;
1706         opts.empty_pathspec_ok = 1;
1707         opts.overlay_mode = -1;
1708         opts.checkout_index = -2;    /* default on */
1709         opts.checkout_worktree = -2; /* default on */
1710
1711         if (argc == 3 && !strcmp(argv[1], "-b")) {
1712                 /*
1713                  * User ran 'git checkout -b <branch>' and expects
1714                  * the same behavior as 'git switch -c <branch>'.
1715                  */
1716                 opts.switch_branch_doing_nothing_is_ok = 0;
1717                 opts.only_merge_on_switching_branches = 1;
1718         }
1719
1720         options = parse_options_dup(checkout_options);
1721         options = add_common_options(&opts, options);
1722         options = add_common_switch_branch_options(&opts, options);
1723         options = add_checkout_path_options(&opts, options);
1724
1725         ret = checkout_main(argc, argv, prefix, &opts,
1726                             options, checkout_usage);
1727         FREE_AND_NULL(options);
1728         return ret;
1729 }
1730
1731 int cmd_switch(int argc, const char **argv, const char *prefix)
1732 {
1733         struct checkout_opts opts;
1734         struct option *options = NULL;
1735         struct option switch_options[] = {
1736                 OPT_STRING('c', "create", &opts.new_branch, N_("branch"),
1737                            N_("create and switch to a new branch")),
1738                 OPT_STRING('C', "force-create", &opts.new_branch_force, N_("branch"),
1739                            N_("create/reset and switch to a branch")),
1740                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1741                          N_("second guess 'git switch <no-such-branch>'")),
1742                 OPT_BOOL(0, "discard-changes", &opts.discard_changes,
1743                          N_("throw away local modifications")),
1744                 OPT_END()
1745         };
1746         int ret;
1747
1748         memset(&opts, 0, sizeof(opts));
1749         opts.dwim_new_local_branch = 1;
1750         opts.accept_ref = 1;
1751         opts.accept_pathspec = 0;
1752         opts.switch_branch_doing_nothing_is_ok = 0;
1753         opts.only_merge_on_switching_branches = 1;
1754         opts.implicit_detach = 0;
1755         opts.can_switch_when_in_progress = 0;
1756         opts.orphan_from_empty_tree = 1;
1757         opts.overlay_mode = -1;
1758
1759         options = parse_options_dup(switch_options);
1760         options = add_common_options(&opts, options);
1761         options = add_common_switch_branch_options(&opts, options);
1762
1763         ret = checkout_main(argc, argv, prefix, &opts,
1764                             options, switch_branch_usage);
1765         FREE_AND_NULL(options);
1766         return ret;
1767 }
1768
1769 int cmd_restore(int argc, const char **argv, const char *prefix)
1770 {
1771         struct checkout_opts opts;
1772         struct option *options;
1773         struct option restore_options[] = {
1774                 OPT_STRING('s', "source", &opts.from_treeish, "<tree-ish>",
1775                            N_("which tree-ish to checkout from")),
1776                 OPT_BOOL('S', "staged", &opts.checkout_index,
1777                            N_("restore the index")),
1778                 OPT_BOOL('W', "worktree", &opts.checkout_worktree,
1779                            N_("restore the working tree (default)")),
1780                 OPT_BOOL(0, "ignore-unmerged", &opts.ignore_unmerged,
1781                          N_("ignore unmerged entries")),
1782                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
1783                 OPT_END()
1784         };
1785         int ret;
1786
1787         memset(&opts, 0, sizeof(opts));
1788         opts.accept_ref = 0;
1789         opts.accept_pathspec = 1;
1790         opts.empty_pathspec_ok = 0;
1791         opts.overlay_mode = 0;
1792         opts.checkout_index = -1;    /* default off */
1793         opts.checkout_worktree = -2; /* default on */
1794         opts.ignore_unmerged_opt = "--ignore-unmerged";
1795
1796         options = parse_options_dup(restore_options);
1797         options = add_common_options(&opts, options);
1798         options = add_checkout_path_options(&opts, options);
1799
1800         ret = checkout_main(argc, argv, prefix, &opts,
1801                             options, restore_usage);
1802         FREE_AND_NULL(options);
1803         return ret;
1804 }