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         int pathspec_file_nul;
  74         const char *pathspec_from_file;
  75
  76         const char *new_branch;
  77         const char *new_branch_force;
  78         const char *new_orphan_branch;
  79         int new_branch_log;
  80         enum branch_track track;
  81         struct diff_options diff_options;
  82         char *conflict_style;
  83
  84         int branch_exists;
  85         const char *prefix;
  86         struct pathspec pathspec;
  87         const char *from_treeish;
  88         struct tree *source_tree;
  89 };
  90
  91 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  92                               int changed)
  93 {
  94         return run_hook_le(NULL, "post-checkout",
  95                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  96                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  97                            changed ? "1" : "0", NULL);
  98         /* "new_commit" can be NULL when checking out from the index before
  99            a commit exists. */
 100
 101 }
 102
 103 static int update_some(const struct object_id *oid, struct strbuf *base,
 104                 const char *pathname, unsigned mode, int stage, void *context)
 105 {
 106         int len;
 107         struct cache_entry *ce;
 108         int pos;
 109
 110         if (S_ISDIR(mode))
 111                 return READ_TREE_RECURSIVE;
 112
 113         len = base->len + strlen(pathname);
 114         ce = make_empty_cache_entry(&the_index, len);
 115         oidcpy(&ce->oid, oid);
 116         memcpy(ce->name, base->buf, base->len);
 117         memcpy(ce->name + base->len, pathname, len - base->len);
 118         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
 119         ce->ce_namelen = len;
 120         ce->ce_mode = create_ce_mode(mode);
 121
 122         /*
 123          * If the entry is the same as the current index, we can leave the old
 124          * entry in place. Whether it is UPTODATE or not, checkout_entry will
 125          * do the right thing.
 126          */
 127         pos = cache_name_pos(ce->name, ce->ce_namelen);
 128         if (pos >= 0) {
 129                 struct cache_entry *old = active_cache[pos];
 130                 if (ce->ce_mode == old->ce_mode &&
 131                     !ce_intent_to_add(old) &&
 132                     oideq(&ce->oid, &old->oid)) {
 133                         old->ce_flags |= CE_UPDATE;
 134                         discard_cache_entry(ce);
 135                         return 0;
 136                 }
 137         }
 138
 139         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 140         return 0;
 141 }
 142
 143 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 144 {
 145         read_tree_recursive(the_repository, tree, "", 0, 0,
 146                             pathspec, update_some, NULL);
 147
 148         /* update the index with the given tree's info
 149          * for all args, expanding wildcards, and exit
 150          * with any non-zero return code.
 151          */
 152         return 0;
 153 }
 154
 155 static int skip_same_name(const struct cache_entry *ce, int pos)
 156 {
 157         while (++pos < active_nr &&
 158                !strcmp(active_cache[pos]->name, ce->name))
 159                 ; /* skip */
 160         return pos;
 161 }
 162
 163 static int check_stage(int stage, const struct cache_entry *ce, int pos,
 164                        int overlay_mode)
 165 {
 166         while (pos < active_nr &&
 167                !strcmp(active_cache[pos]->name, ce->name)) {
 168                 if (ce_stage(active_cache[pos]) == stage)
 169                         return 0;
 170                 pos++;
 171         }
 172         if (!overlay_mode)
 173                 return 0;
 174         if (stage == 2)
 175                 return error(_("path '%s' does not have our version"), ce->name);
 176         else
 177                 return error(_("path '%s' does not have their version"), ce->name);
 178 }
 179
 180 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 181 {
 182         unsigned seen = 0;
 183         const char *name = ce->name;
 184
 185         while (pos < active_nr) {
 186                 ce = active_cache[pos];
 187                 if (strcmp(name, ce->name))
 188                         break;
 189                 seen |= (1 << ce_stage(ce));
 190                 pos++;
 191         }
 192         if ((stages & seen) != stages)
 193                 return error(_("path '%s' does not have all necessary versions"),
 194                              name);
 195         return 0;
 196 }
 197
 198 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 199                           const struct checkout *state, int *nr_checkouts,
 200                           int overlay_mode)
 201 {
 202         while (pos < active_nr &&
 203                !strcmp(active_cache[pos]->name, ce->name)) {
 204                 if (ce_stage(active_cache[pos]) == stage)
 205                         return checkout_entry(active_cache[pos], state,
 206                                               NULL, nr_checkouts);
 207                 pos++;
 208         }
 209         if (!overlay_mode) {
 210                 unlink_entry(ce);
 211                 return 0;
 212         }
 213         if (stage == 2)
 214                 return error(_("path '%s' does not have our version"), ce->name);
 215         else
 216                 return error(_("path '%s' does not have their version"), ce->name);
 217 }
 218
 219 static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
 220 {
 221         struct cache_entry *ce = active_cache[pos];
 222         const char *path = ce->name;
 223         mmfile_t ancestor, ours, theirs;
 224         int status;
 225         struct object_id oid;
 226         mmbuffer_t result_buf;
 227         struct object_id threeway[3];
 228         unsigned mode = 0;
 229
 230         memset(threeway, 0, sizeof(threeway));
 231         while (pos < active_nr) {
 232                 int stage;
 233                 stage = ce_stage(ce);
 234                 if (!stage || strcmp(path, ce->name))
 235                         break;
 236                 oidcpy(&threeway[stage - 1], &ce->oid);
 237                 if (stage == 2)
 238                         mode = create_ce_mode(ce->ce_mode);
 239                 pos++;
 240                 ce = active_cache[pos];
 241         }
 242         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 243                 return error(_("path '%s' does not have necessary versions"), path);
 244
 245         read_mmblob(&ancestor, &threeway[0]);
 246         read_mmblob(&ours, &threeway[1]);
 247         read_mmblob(&theirs, &threeway[2]);
 248
 249         /*
 250          * NEEDSWORK: re-create conflicts from merges with
 251          * merge.renormalize set, too
 252          */
 253         status = ll_merge(&result_buf, path, &ancestor, "base",
 254                           &ours, "ours", &theirs, "theirs",
 255                           state->istate, NULL);
 256         free(ancestor.ptr);
 257         free(ours.ptr);
 258         free(theirs.ptr);
 259         if (status < 0 || !result_buf.ptr) {
 260                 free(result_buf.ptr);
 261                 return error(_("path '%s': cannot merge"), path);
 262         }
 263
 264         /*
 265          * NEEDSWORK:
 266          * There is absolutely no reason to write this as a blob object
 267          * and create a phony cache entry.  This hack is primarily to get
 268          * to the write_entry() machinery that massages the contents to
 269          * work-tree format and writes out which only allows it for a
 270          * cache entry.  The code in write_entry() needs to be refactored
 271          * to allow us to feed a <buffer, size, mode> instead of a cache
 272          * entry.  Such a refactoring would help merge_recursive as well
 273          * (it also writes the merge result to the object database even
 274          * when it may contain conflicts).
 275          */
 276         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 277                 die(_("Unable to add merge result for '%s'"), path);
 278         free(result_buf.ptr);
 279         ce = make_transient_cache_entry(mode, &oid, path, 2);
 280         if (!ce)
 281                 die(_("make_cache_entry failed for path '%s'"), path);
 282         status = checkout_entry(ce, state, NULL, nr_checkouts);
 283         discard_cache_entry(ce);
 284         return status;
 285 }
 286
 287 static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
 288                                          char *ps_matched,
 289                                          const struct checkout_opts *opts)
 290 {
 291         ce->ce_flags &= ~CE_MATCHED;
 292         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 293                 return;
 294         if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 295                 /*
 296                  * "git checkout tree-ish -- path", but this entry
 297                  * is in the original index but is not in tree-ish
 298                  * or does not match the pathspec; it will not be
 299                  * checked out to the working tree.  We will not do
 300                  * anything to this entry at all.
 301                  */
 302                 return;
 303         /*
 304          * Either this entry came from the tree-ish we are
 305          * checking the paths out of, or we are checking out
 306          * of the index.
 307          *
 308          * If it comes from the tree-ish, we already know it
 309          * matches the pathspec and could just stamp
 310          * CE_MATCHED to it from update_some(). But we still
 311          * need ps_matched and read_tree_recursive (and
 312          * eventually tree_entry_interesting) cannot fill
 313          * ps_matched yet. Once it can, we can avoid calling
 314          * match_pathspec() for _all_ entries when
 315          * opts->source_tree != NULL.
 316          */
 317         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 318                 ce->ce_flags |= CE_MATCHED;
 319 }
 320
 321 static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
 322                                             char *ps_matched,
 323                                             const struct checkout_opts *opts)
 324 {
 325         ce->ce_flags &= ~CE_MATCHED;
 326         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 327                 return;
 328         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
 329                 ce->ce_flags |= CE_MATCHED;
 330                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 331                         /*
 332                          * In overlay mode, but the path is not in
 333                          * tree-ish, which means we should remove it
 334                          * from the index and the working tree.
 335                          */
 336                         ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
 337         }
 338 }
 339
 340 static int checkout_worktree(const struct checkout_opts *opts)
 341 {
 342         struct checkout state = CHECKOUT_INIT;
 343         int nr_checkouts = 0, nr_unmerged = 0;
 344         int errs = 0;
 345         int pos;
 346
 347         state.force = 1;
 348         state.refresh_cache = 1;
 349         state.istate = &the_index;
 350
 351         enable_delayed_checkout(&state);
 352         for (pos = 0; pos < active_nr; pos++) {
 353                 struct cache_entry *ce = active_cache[pos];
 354                 if (ce->ce_flags & CE_MATCHED) {
 355                         if (!ce_stage(ce)) {
 356                                 errs |= checkout_entry(ce, &state,
 357                                                        NULL, &nr_checkouts);
 358                                 continue;
 359                         }
 360                         if (opts->writeout_stage)
 361                                 errs |= checkout_stage(opts->writeout_stage,
 362                                                        ce, pos,
 363                                                        &state,
 364                                                        &nr_checkouts, opts->overlay_mode);
 365                         else if (opts->merge)
 366                                 errs |= checkout_merged(pos, &state,
 367                                                         &nr_unmerged);
 368                         pos = skip_same_name(ce, pos) - 1;
 369                 }
 370         }
 371         remove_marked_cache_entries(&the_index, 1);
 372         remove_scheduled_dirs();
 373         errs |= finish_delayed_checkout(&state, &nr_checkouts);
 374
 375         if (opts->count_checkout_paths) {
 376                 if (nr_unmerged)
 377                         fprintf_ln(stderr, Q_("Recreated %d merge conflict",
 378                                               "Recreated %d merge conflicts",
 379                                               nr_unmerged),
 380                                    nr_unmerged);
 381                 if (opts->source_tree)
 382                         fprintf_ln(stderr, Q_("Updated %d path from %s",
 383                                               "Updated %d paths from %s",
 384                                               nr_checkouts),
 385                                    nr_checkouts,
 386                                    find_unique_abbrev(&opts->source_tree->object.oid,
 387                                                       DEFAULT_ABBREV));
 388                 else if (!nr_unmerged || nr_checkouts)
 389                         fprintf_ln(stderr, Q_("Updated %d path from the index",
 390                                               "Updated %d paths from the index",
 391                                               nr_checkouts),
 392                                    nr_checkouts);
 393         }
 394
 395         return errs;
 396 }
 397
 398 static int checkout_paths(const struct checkout_opts *opts,
 399                           const char *revision)
 400 {
 401         int pos;
 402         static char *ps_matched;
 403         struct object_id rev;
 404         struct commit *head;
 405         int errs = 0;
 406         struct lock_file lock_file = LOCK_INIT;
 407         int checkout_index;
 408
 409         trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
 410
 411         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 412                 die(_("'%s' cannot be used with updating paths"), "--track");
 413
 414         if (opts->new_branch_log)
 415                 die(_("'%s' cannot be used with updating paths"), "-l");
 416
 417         if (opts->ignore_unmerged && opts->patch_mode)
 418                 die(_("'%s' cannot be used with updating paths"),
 419                     opts->ignore_unmerged_opt);
 420
 421         if (opts->force_detach)
 422                 die(_("'%s' cannot be used with updating paths"), "--detach");
 423
 424         if (opts->merge && opts->patch_mode)
 425                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 426
 427         if (opts->ignore_unmerged && opts->merge)
 428                 die(_("'%s' cannot be used with %s"),
 429                     opts->ignore_unmerged_opt, "-m");
 430
 431         if (opts->new_branch)
 432                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 433                     opts->new_branch);
 434
 435         if (!opts->checkout_worktree && !opts->checkout_index)
 436                 die(_("neither '%s' or '%s' is specified"),
 437                     "--staged", "--worktree");
 438
 439         if (!opts->checkout_worktree && !opts->from_treeish)
 440                 die(_("'%s' must be used when '%s' is not specified"),
 441                     "--worktree", "--source");
 442
 443         if (opts->checkout_index && !opts->checkout_worktree &&
 444             opts->writeout_stage)
 445                 die(_("'%s' or '%s' cannot be used with %s"),
 446                     "--ours", "--theirs", "--staged");
 447
 448         if (opts->checkout_index && !opts->checkout_worktree &&
 449             opts->merge)
 450                 die(_("'%s' or '%s' cannot be used with %s"),
 451                     "--merge", "--conflict", "--staged");
 452
 453         if (opts->patch_mode) {
 454                 const char *patch_mode;
 455
 456                 if (opts->checkout_index && opts->checkout_worktree)
 457                         patch_mode = "--patch=checkout";
 458                 else if (opts->checkout_index && !opts->checkout_worktree)
 459                         patch_mode = "--patch=reset";
 460                 else if (!opts->checkout_index && opts->checkout_worktree)
 461                         patch_mode = "--patch=worktree";
 462                 else
 463                         BUG("either flag must have been set, worktree=%d, index=%d",
 464                             opts->checkout_worktree, opts->checkout_index);
 465                 return run_add_interactive(revision, patch_mode, &opts->pathspec);
 466         }
 467
 468         repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 469         if (read_cache_preload(&opts->pathspec) < 0)
 470                 return error(_("index file corrupt"));
 471
 472         if (opts->source_tree)
 473                 read_tree_some(opts->source_tree, &opts->pathspec);
 474
 475         ps_matched = xcalloc(opts->pathspec.nr, 1);
 476
 477         /*
 478          * Make sure all pathspecs participated in locating the paths
 479          * to be checked out.
 480          */
 481         for (pos = 0; pos < active_nr; pos++)
 482                 if (opts->overlay_mode)
 483                         mark_ce_for_checkout_overlay(active_cache[pos],
 484                                                      ps_matched,
 485                                                      opts);
 486                 else
 487                         mark_ce_for_checkout_no_overlay(active_cache[pos],
 488                                                         ps_matched,
 489                                                         opts);
 490
 491         if (report_path_error(ps_matched, &opts->pathspec)) {
 492                 free(ps_matched);
 493                 return 1;
 494         }
 495         free(ps_matched);
 496
 497         /* "checkout -m path" to recreate conflicted state */
 498         if (opts->merge)
 499                 unmerge_marked_index(&the_index);
 500
 501         /* Any unmerged paths? */
 502         for (pos = 0; pos < active_nr; pos++) {
 503                 const struct cache_entry *ce = active_cache[pos];
 504                 if (ce->ce_flags & CE_MATCHED) {
 505                         if (!ce_stage(ce))
 506                                 continue;
 507                         if (opts->ignore_unmerged) {
 508                                 if (!opts->quiet)
 509                                         warning(_("path '%s' is unmerged"), ce->name);
 510                         } else if (opts->writeout_stage) {
 511                                 errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
 512                         } else if (opts->merge) {
 513                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 514                         } else {
 515                                 errs = 1;
 516                                 error(_("path '%s' is unmerged"), ce->name);
 517                         }
 518                         pos = skip_same_name(ce, pos) - 1;
 519                 }
 520         }
 521         if (errs)
 522                 return 1;
 523
 524         /* Now we are committed to check them out */
 525         if (opts->checkout_worktree)
 526                 errs |= checkout_worktree(opts);
 527         else
 528                 remove_marked_cache_entries(&the_index, 1);
 529
 530         /*
 531          * Allow updating the index when checking out from the index.
 532          * This is to save new stat info.
 533          */
 534         if (opts->checkout_worktree && !opts->checkout_index && !opts->source_tree)
 535                 checkout_index = 1;
 536         else
 537                 checkout_index = opts->checkout_index;
 538
 539         if (checkout_index) {
 540                 if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 541                         die(_("unable to write new index file"));
 542         } else {
 543                 /*
 544                  * NEEDSWORK: if --worktree is not specified, we
 545                  * should save stat info of checked out files in the
 546                  * index to avoid the next (potentially costly)
 547                  * refresh. But it's a bit tricker to do...
 548                  */
 549                 rollback_lock_file(&lock_file);
 550         }
 551
 552         read_ref_full("HEAD", 0, &rev, NULL);
 553         head = lookup_commit_reference_gently(the_repository, &rev, 1);
 554
 555         errs |= post_checkout_hook(head, head, 0);
 556         return errs;
 557 }
 558
 559 static void show_local_changes(struct object *head,
 560                                const struct diff_options *opts)
 561 {
 562         struct rev_info rev;
 563         /* I think we want full paths, even if we're in a subdirectory. */
 564         repo_init_revisions(the_repository, &rev, NULL);
 565         rev.diffopt.flags = opts->flags;
 566         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 567         diff_setup_done(&rev.diffopt);
 568         add_pending_object(&rev, head, NULL);
 569         run_diff_index(&rev, 0);
 570 }
 571
 572 static void describe_detached_head(const char *msg, struct commit *commit)
 573 {
 574         struct strbuf sb = STRBUF_INIT;
 575
 576         if (!parse_commit(commit))
 577                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 578         if (print_sha1_ellipsis()) {
 579                 fprintf(stderr, "%s %s... %s\n", msg,
 580                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 581         } else {
 582                 fprintf(stderr, "%s %s %s\n", msg,
 583                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 584         }
 585         strbuf_release(&sb);
 586 }
 587
 588 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 589                       int worktree, int *writeout_error)
 590 {
 591         struct unpack_trees_options opts;
 592         struct tree_desc tree_desc;
 593
 594         memset(&opts, 0, sizeof(opts));
 595         opts.head_idx = -1;
 596         opts.update = worktree;
 597         opts.skip_unmerged = !worktree;
 598         opts.reset = 1;
 599         opts.merge = 1;
 600         opts.fn = oneway_merge;
 601         opts.verbose_update = o->show_progress;
 602         opts.src_index = &the_index;
 603         opts.dst_index = &the_index;
 604         parse_tree(tree);
 605         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 606         switch (unpack_trees(1, &tree_desc, &opts)) {
 607         case -2:
 608                 *writeout_error = 1;
 609                 /*
 610                  * We return 0 nevertheless, as the index is all right
 611                  * and more importantly we have made best efforts to
 612                  * update paths in the work tree, and we cannot revert
 613                  * them.
 614                  */
 615                 /* fallthrough */
 616         case 0:
 617                 return 0;
 618         default:
 619                 return 128;
 620         }
 621 }
 622
 623 struct branch_info {
 624         const char *name; /* The short name used */
 625         const char *path; /* The full name of a real branch */
 626         struct commit *commit; /* The named commit */
 627         /*
 628          * if not null the branch is detached because it's already
 629          * checked out in this checkout
 630          */
 631         char *checkout;
 632 };
 633
 634 static void setup_branch_path(struct branch_info *branch)
 635 {
 636         struct strbuf buf = STRBUF_INIT;
 637
 638         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 639         if (strcmp(buf.buf, branch->name))
 640                 branch->name = xstrdup(buf.buf);
 641         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 642         branch->path = strbuf_detach(&buf, NULL);
 643 }
 644
 645 static int merge_working_tree(const struct checkout_opts *opts,
 646                               struct branch_info *old_branch_info,
 647                               struct branch_info *new_branch_info,
 648                               int *writeout_error)
 649 {
 650         int ret;
 651         struct lock_file lock_file = LOCK_INIT;
 652         struct tree *new_tree;
 653
 654         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 655         if (read_cache_preload(NULL) < 0)
 656                 return error(_("index file corrupt"));
 657
 658         resolve_undo_clear();
 659         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 660                 if (new_branch_info->commit)
 661                         BUG("'switch --orphan' should never accept a commit as starting point");
 662                 new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
 663         } else
 664                 new_tree = get_commit_tree(new_branch_info->commit);
 665         if (opts->discard_changes) {
 666                 ret = reset_tree(new_tree, opts, 1, writeout_error);
 667                 if (ret)
 668                         return ret;
 669         } else {
 670                 struct tree_desc trees[2];
 671                 struct tree *tree;
 672                 struct unpack_trees_options topts;
 673
 674                 memset(&topts, 0, sizeof(topts));
 675                 topts.head_idx = -1;
 676                 topts.src_index = &the_index;
 677                 topts.dst_index = &the_index;
 678
 679                 setup_unpack_trees_porcelain(&topts, "checkout");
 680
 681                 refresh_cache(REFRESH_QUIET);
 682
 683                 if (unmerged_cache()) {
 684                         error(_("you need to resolve your current index first"));
 685                         return 1;
 686                 }
 687
 688                 /* 2-way merge to the new branch */
 689                 topts.initial_checkout = is_cache_unborn();
 690                 topts.update = 1;
 691                 topts.merge = 1;
 692                 topts.quiet = opts->merge && old_branch_info->commit;
 693                 topts.verbose_update = opts->show_progress;
 694                 topts.fn = twoway_merge;
 695                 if (opts->overwrite_ignore) {
 696                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 697                         topts.dir->flags |= DIR_SHOW_IGNORED;
 698                         setup_standard_excludes(topts.dir);
 699                 }
 700                 tree = parse_tree_indirect(old_branch_info->commit ?
 701                                            &old_branch_info->commit->object.oid :
 702                                            the_hash_algo->empty_tree);
 703                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 704                 parse_tree(new_tree);
 705                 tree = new_tree;
 706                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 707
 708                 ret = unpack_trees(2, trees, &topts);
 709                 clear_unpack_trees_porcelain(&topts);
 710                 if (ret == -1) {
 711                         /*
 712                          * Unpack couldn't do a trivial merge; either
 713                          * give up or do a real merge, depending on
 714                          * whether the merge flag was used.
 715                          */
 716                         struct tree *work;
 717                         struct tree *old_tree;
 718                         struct merge_options o;
 719                         struct strbuf sb = STRBUF_INIT;
 720                         struct strbuf old_commit_shortname = STRBUF_INIT;
 721
 722                         if (!opts->merge)
 723                                 return 1;
 724
 725                         /*
 726                          * Without old_branch_info->commit, the below is the same as
 727                          * the two-tree unpack we already tried and failed.
 728                          */
 729                         if (!old_branch_info->commit)
 730                                 return 1;
 731                         old_tree = get_commit_tree(old_branch_info->commit);
 732
 733                         if (repo_index_has_changes(the_repository, old_tree, &sb))
 734                                 die(_("cannot continue with staged changes in "
 735                                       "the following files:\n%s"), sb.buf);
 736                         strbuf_release(&sb);
 737
 738                         /* Do more real merge */
 739
 740                         /*
 741                          * We update the index fully, then write the
 742                          * tree from the index, then merge the new
 743                          * branch with the current tree, with the old
 744                          * branch as the base. Then we reset the index
 745                          * (but not the working tree) to the new
 746                          * branch, leaving the working tree as the
 747                          * merged version, but skipping unmerged
 748                          * entries in the index.
 749                          */
 750
 751                         add_files_to_cache(NULL, NULL, 0);
 752                         /*
 753                          * NEEDSWORK: carrying over local changes
 754                          * when branches have different end-of-line
 755                          * normalization (or clean+smudge rules) is
 756                          * a pain; plumb in an option to set
 757                          * o.renormalize?
 758                          */
 759                         init_merge_options(&o, the_repository);
 760                         o.verbosity = 0;
 761                         work = write_in_core_index_as_tree(the_repository);
 762
 763                         ret = reset_tree(new_tree,
 764                                          opts, 1,
 765                                          writeout_error);
 766                         if (ret)
 767                                 return ret;
 768                         o.ancestor = old_branch_info->name;
 769                         if (old_branch_info->name == NULL) {
 770                                 strbuf_add_unique_abbrev(&old_commit_shortname,
 771                                                          &old_branch_info->commit->object.oid,
 772                                                          DEFAULT_ABBREV);
 773                                 o.ancestor = old_commit_shortname.buf;
 774                         }
 775                         o.branch1 = new_branch_info->name;
 776                         o.branch2 = "local";
 777                         ret = merge_trees(&o,
 778                                           new_tree,
 779                                           work,
 780                                           old_tree);
 781                         if (ret < 0)
 782                                 exit(128);
 783                         ret = reset_tree(new_tree,
 784                                          opts, 0,
 785                                          writeout_error);
 786                         strbuf_release(&o.obuf);
 787                         strbuf_release(&old_commit_shortname);
 788                         if (ret)
 789                                 return ret;
 790                 }
 791         }
 792
 793         if (!active_cache_tree)
 794                 active_cache_tree = cache_tree();
 795
 796         if (!cache_tree_fully_valid(active_cache_tree))
 797                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 798
 799         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 800                 die(_("unable to write new index file"));
 801
 802         if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
 803                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 804
 805         return 0;
 806 }
 807
 808 static void report_tracking(struct branch_info *new_branch_info)
 809 {
 810         struct strbuf sb = STRBUF_INIT;
 811         struct branch *branch = branch_get(new_branch_info->name);
 812
 813         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 814                 return;
 815         fputs(sb.buf, stdout);
 816         strbuf_release(&sb);
 817 }
 818
 819 static void update_refs_for_switch(const struct checkout_opts *opts,
 820                                    struct branch_info *old_branch_info,
 821                                    struct branch_info *new_branch_info)
 822 {
 823         struct strbuf msg = STRBUF_INIT;
 824         const char *old_desc, *reflog_msg;
 825         if (opts->new_branch) {
 826                 if (opts->new_orphan_branch) {
 827                         char *refname;
 828
 829                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 830                         if (opts->new_branch_log &&
 831                             !should_autocreate_reflog(refname)) {
 832                                 int ret;
 833                                 struct strbuf err = STRBUF_INIT;
 834
 835                                 ret = safe_create_reflog(refname, 1, &err);
 836                                 if (ret) {
 837                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 838                                                 opts->new_orphan_branch, err.buf);
 839                                         strbuf_release(&err);
 840                                         free(refname);
 841                                         return;
 842                                 }
 843                                 strbuf_release(&err);
 844                         }
 845                         free(refname);
 846                 }
 847                 else
 848                         create_branch(the_repository,
 849                                       opts->new_branch, new_branch_info->name,
 850                                       opts->new_branch_force ? 1 : 0,
 851                                       opts->new_branch_force ? 1 : 0,
 852                                       opts->new_branch_log,
 853                                       opts->quiet,
 854                                       opts->track);
 855                 new_branch_info->name = opts->new_branch;
 856                 setup_branch_path(new_branch_info);
 857         }
 858
 859         old_desc = old_branch_info->name;
 860         if (!old_desc && old_branch_info->commit)
 861                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 862
 863         reflog_msg = getenv("GIT_REFLOG_ACTION");
 864         if (!reflog_msg)
 865                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 866                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 867         else
 868                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 869
 870         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 871                 /* Nothing to do. */
 872         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 873                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 874                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 875                 if (!opts->quiet) {
 876                         if (old_branch_info->path &&
 877                             advice_detached_head && !opts->force_detach)
 878                                 detach_advice(new_branch_info->name);
 879                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 880                 }
 881         } else if (new_branch_info->path) {     /* Switch branches. */
 882                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 883                         die(_("unable to update HEAD"));
 884                 if (!opts->quiet) {
 885                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 886                                 if (opts->new_branch_force)
 887                                         fprintf(stderr, _("Reset branch '%s'\n"),
 888                                                 new_branch_info->name);
 889                                 else
 890                                         fprintf(stderr, _("Already on '%s'\n"),
 891                                                 new_branch_info->name);
 892                         } else if (opts->new_branch) {
 893                                 if (opts->branch_exists)
 894                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 895                                 else
 896                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 897                         } else {
 898                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 899                                         new_branch_info->name);
 900                         }
 901                 }
 902                 if (old_branch_info->path && old_branch_info->name) {
 903                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 904                                 delete_reflog(old_branch_info->path);
 905                 }
 906         }
 907         remove_branch_state(the_repository, !opts->quiet);
 908         strbuf_release(&msg);
 909         if (!opts->quiet &&
 910             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 911                 report_tracking(new_branch_info);
 912 }
 913
 914 static int add_pending_uninteresting_ref(const char *refname,
 915                                          const struct object_id *oid,
 916                                          int flags, void *cb_data)
 917 {
 918         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 919         return 0;
 920 }
 921
 922 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 923 {
 924         strbuf_addstr(sb, "  ");
 925         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 926         strbuf_addch(sb, ' ');
 927         if (!parse_commit(commit))
 928                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 929         strbuf_addch(sb, '\n');
 930 }
 931
 932 #define ORPHAN_CUTOFF 4
 933 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 934 {
 935         struct commit *c, *last = NULL;
 936         struct strbuf sb = STRBUF_INIT;
 937         int lost = 0;
 938         while ((c = get_revision(revs)) != NULL) {
 939                 if (lost < ORPHAN_CUTOFF)
 940                         describe_one_orphan(&sb, c);
 941                 last = c;
 942                 lost++;
 943         }
 944         if (ORPHAN_CUTOFF < lost) {
 945                 int more = lost - ORPHAN_CUTOFF;
 946                 if (more == 1)
 947                         describe_one_orphan(&sb, last);
 948                 else
 949                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 950         }
 951
 952         fprintf(stderr,
 953                 Q_(
 954                 /* The singular version */
 955                 "Warning: you are leaving %d commit behind, "
 956                 "not connected to\n"
 957                 "any of your branches:\n\n"
 958                 "%s\n",
 959                 /* The plural version */
 960                 "Warning: you are leaving %d commits behind, "
 961                 "not connected to\n"
 962                 "any of your branches:\n\n"
 963                 "%s\n",
 964                 /* Give ngettext() the count */
 965                 lost),
 966                 lost,
 967                 sb.buf);
 968         strbuf_release(&sb);
 969
 970         if (advice_detached_head)
 971                 fprintf(stderr,
 972                         Q_(
 973                         /* The singular version */
 974                         "If you want to keep it 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                         /* The plural version */
 978                         "If you want to keep them by creating a new branch, "
 979                         "this may be a good time\nto do so with:\n\n"
 980                         " git branch <new-branch-name> %s\n\n",
 981                         /* Give ngettext() the count */
 982                         lost),
 983                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 984 }
 985
 986 /*
 987  * We are about to leave commit that was at the tip of a detached
 988  * HEAD.  If it is not reachable from any ref, this is the last chance
 989  * for the user to do so without resorting to reflog.
 990  */
 991 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 992 {
 993         struct rev_info revs;
 994         struct object *object = &old_commit->object;
 995
 996         repo_init_revisions(the_repository, &revs, NULL);
 997         setup_revisions(0, NULL, &revs, NULL);
 998
 999         object->flags &= ~UNINTERESTING;
1000         add_pending_object(&revs, object, oid_to_hex(&object->oid));
1001
1002         for_each_ref(add_pending_uninteresting_ref, &revs);
1003         if (new_commit)
1004                 add_pending_oid(&revs, "HEAD",
1005                                 &new_commit->object.oid,
1006                                 UNINTERESTING);
1007
1008         if (prepare_revision_walk(&revs))
1009                 die(_("internal error in revision walk"));
1010         if (!(old_commit->object.flags & UNINTERESTING))
1011                 suggest_reattach(old_commit, &revs);
1012         else
1013                 describe_detached_head(_("Previous HEAD position was"), old_commit);
1014
1015         /* Clean up objects used, as they will be reused. */
1016         clear_commit_marks_all(ALL_REV_FLAGS);
1017 }
1018
1019 static int switch_branches(const struct checkout_opts *opts,
1020                            struct branch_info *new_branch_info)
1021 {
1022         int ret = 0;
1023         struct branch_info old_branch_info;
1024         void *path_to_free;
1025         struct object_id rev;
1026         int flag, writeout_error = 0;
1027         int do_merge = 1;
1028
1029         trace2_cmd_mode("branch");
1030
1031         memset(&old_branch_info, 0, sizeof(old_branch_info));
1032         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1033         if (old_branch_info.path)
1034                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1035         if (!(flag & REF_ISSYMREF))
1036                 old_branch_info.path = NULL;
1037
1038         if (old_branch_info.path)
1039                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1040
1041         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
1042                 if (new_branch_info->name)
1043                         BUG("'switch --orphan' should never accept a commit as starting point");
1044                 new_branch_info->commit = NULL;
1045                 new_branch_info->name = "(empty)";
1046                 do_merge = 1;
1047         }
1048
1049         if (!new_branch_info->name) {
1050                 new_branch_info->name = "HEAD";
1051                 new_branch_info->commit = old_branch_info.commit;
1052                 if (!new_branch_info->commit)
1053                         die(_("You are on a branch yet to be born"));
1054                 parse_commit_or_die(new_branch_info->commit);
1055
1056                 if (opts->only_merge_on_switching_branches)
1057                         do_merge = 0;
1058         }
1059
1060         if (do_merge) {
1061                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1062                 if (ret) {
1063                         free(path_to_free);
1064                         return ret;
1065                 }
1066         }
1067
1068         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1069                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1070
1071         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1072
1073         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1074         free(path_to_free);
1075         return ret || writeout_error;
1076 }
1077
1078 static int git_checkout_config(const char *var, const char *value, void *cb)
1079 {
1080         if (!strcmp(var, "diff.ignoresubmodules")) {
1081                 struct checkout_opts *opts = cb;
1082                 handle_ignore_submodules_arg(&opts->diff_options, value);
1083                 return 0;
1084         }
1085
1086         if (starts_with(var, "submodule."))
1087                 return git_default_submodule_config(var, value, NULL);
1088
1089         return git_xmerge_config(var, value, NULL);
1090 }
1091
1092 static void setup_new_branch_info_and_source_tree(
1093         struct branch_info *new_branch_info,
1094         struct checkout_opts *opts,
1095         struct object_id *rev,
1096         const char *arg)
1097 {
1098         struct tree **source_tree = &opts->source_tree;
1099         struct object_id branch_rev;
1100
1101         new_branch_info->name = arg;
1102         setup_branch_path(new_branch_info);
1103
1104         if (!check_refname_format(new_branch_info->path, 0) &&
1105             !read_ref(new_branch_info->path, &branch_rev))
1106                 oidcpy(rev, &branch_rev);
1107         else
1108                 new_branch_info->path = NULL; /* not an existing branch */
1109
1110         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1111         if (!new_branch_info->commit) {
1112                 /* not a commit */
1113                 *source_tree = parse_tree_indirect(rev);
1114         } else {
1115                 parse_commit_or_die(new_branch_info->commit);
1116                 *source_tree = get_commit_tree(new_branch_info->commit);
1117         }
1118 }
1119
1120 static int parse_branchname_arg(int argc, const char **argv,
1121                                 int dwim_new_local_branch_ok,
1122                                 struct branch_info *new_branch_info,
1123                                 struct checkout_opts *opts,
1124                                 struct object_id *rev,
1125                                 int *dwim_remotes_matched)
1126 {
1127         const char **new_branch = &opts->new_branch;
1128         int argcount = 0;
1129         const char *arg;
1130         int dash_dash_pos;
1131         int has_dash_dash = 0;
1132         int i;
1133
1134         /*
1135          * case 1: git checkout <ref> -- [<paths>]
1136          *
1137          *   <ref> must be a valid tree, everything after the '--' must be
1138          *   a path.
1139          *
1140          * case 2: git checkout -- [<paths>]
1141          *
1142          *   everything after the '--' must be paths.
1143          *
1144          * case 3: git checkout <something> [--]
1145          *
1146          *   (a) If <something> is a commit, that is to
1147          *       switch to the branch or detach HEAD at it.  As a special case,
1148          *       if <something> is A...B (missing A or B means HEAD but you can
1149          *       omit at most one side), and if there is a unique merge base
1150          *       between A and B, A...B names that merge base.
1151          *
1152          *   (b) If <something> is _not_ a commit, either "--" is present
1153          *       or <something> is not a path, no -t or -b was given, and
1154          *       and there is a tracking branch whose name is <something>
1155          *       in one and only one remote (or if the branch exists on the
1156          *       remote named in checkout.defaultRemote), then this is a
1157          *       short-hand to fork local <something> from that
1158          *       remote-tracking branch.
1159          *
1160          *   (c) Otherwise, if "--" is present, treat it like case (1).
1161          *
1162          *   (d) Otherwise :
1163          *       - if it's a reference, treat it like case (1)
1164          *       - else if it's a path, treat it like case (2)
1165          *       - else: fail.
1166          *
1167          * case 4: git checkout <something> <paths>
1168          *
1169          *   The first argument must not be ambiguous.
1170          *   - If it's *only* a reference, treat it like case (1).
1171          *   - If it's only a path, treat it like case (2).
1172          *   - else: fail.
1173          *
1174          */
1175         if (!argc)
1176                 return 0;
1177
1178         if (!opts->accept_pathspec) {
1179                 if (argc > 1)
1180                         die(_("only one reference expected"));
1181                 has_dash_dash = 1; /* helps disambiguate */
1182         }
1183
1184         arg = argv[0];
1185         dash_dash_pos = -1;
1186         for (i = 0; i < argc; i++) {
1187                 if (opts->accept_pathspec && !strcmp(argv[i], "--")) {
1188                         dash_dash_pos = i;
1189                         break;
1190                 }
1191         }
1192         if (dash_dash_pos == 0)
1193                 return 1; /* case (2) */
1194         else if (dash_dash_pos == 1)
1195                 has_dash_dash = 1; /* case (3) or (1) */
1196         else if (dash_dash_pos >= 2)
1197                 die(_("only one reference expected, %d given."), dash_dash_pos);
1198         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1199
1200         if (!strcmp(arg, "-"))
1201                 arg = "@{-1}";
1202
1203         if (get_oid_mb(arg, rev)) {
1204                 /*
1205                  * Either case (3) or (4), with <something> not being
1206                  * a commit, or an attempt to use case (1) with an
1207                  * invalid ref.
1208                  *
1209                  * It's likely an error, but we need to find out if
1210                  * we should auto-create the branch, case (3).(b).
1211                  */
1212                 int recover_with_dwim = dwim_new_local_branch_ok;
1213
1214                 int could_be_checkout_paths = !has_dash_dash &&
1215                         check_filename(opts->prefix, arg);
1216
1217                 if (!has_dash_dash && !no_wildcard(arg))
1218                         recover_with_dwim = 0;
1219
1220                 /*
1221                  * Accept "git checkout foo", "git checkout foo --"
1222                  * and "git switch foo" as candidates for dwim.
1223                  */
1224                 if (!(argc == 1 && !has_dash_dash) &&
1225                     !(argc == 2 && has_dash_dash) &&
1226                     opts->accept_pathspec)
1227                         recover_with_dwim = 0;
1228
1229                 if (recover_with_dwim) {
1230                         const char *remote = unique_tracking_name(arg, rev,
1231                                                                   dwim_remotes_matched);
1232                         if (remote) {
1233                                 if (could_be_checkout_paths)
1234                                         die(_("'%s' could be both a local file and a tracking branch.\n"
1235                                               "Please use -- (and optionally --no-guess) to disambiguate"),
1236                                             arg);
1237                                 *new_branch = arg;
1238                                 arg = remote;
1239                                 /* DWIMmed to create local branch, case (3).(b) */
1240                         } else {
1241                                 recover_with_dwim = 0;
1242                         }
1243                 }
1244
1245                 if (!recover_with_dwim) {
1246                         if (has_dash_dash)
1247                                 die(_("invalid reference: %s"), arg);
1248                         return argcount;
1249                 }
1250         }
1251
1252         /* we can't end up being in (2) anymore, eat the argument */
1253         argcount++;
1254         argv++;
1255         argc--;
1256
1257         setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1258
1259         if (!opts->source_tree)                   /* case (1): want a tree */
1260                 die(_("reference is not a tree: %s"), arg);
1261
1262         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1263                 /*
1264                  * Do not complain the most common case
1265                  *      git checkout branch
1266                  * even if there happen to be a file called 'branch';
1267                  * it would be extremely annoying.
1268                  */
1269                 if (argc)
1270                         verify_non_filename(opts->prefix, arg);
1271         } else if (opts->accept_pathspec) {
1272                 argcount++;
1273                 argv++;
1274                 argc--;
1275         }
1276
1277         return argcount;
1278 }
1279
1280 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1281 {
1282         int status;
1283         struct strbuf branch_ref = STRBUF_INIT;
1284
1285         trace2_cmd_mode("unborn");
1286
1287         if (!opts->new_branch)
1288                 die(_("You are on a branch yet to be born"));
1289         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1290         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1291         strbuf_release(&branch_ref);
1292         if (!opts->quiet)
1293                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1294                         opts->new_branch);
1295         return status;
1296 }
1297
1298 static void die_expecting_a_branch(const struct branch_info *branch_info)
1299 {
1300         struct object_id oid;
1301         char *to_free;
1302
1303         if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free) == 1) {
1304                 const char *ref = to_free;
1305
1306                 if (skip_prefix(ref, "refs/tags/", &ref))
1307                         die(_("a branch is expected, got tag '%s'"), ref);
1308                 if (skip_prefix(ref, "refs/remotes/", &ref))
1309                         die(_("a branch is expected, got remote branch '%s'"), ref);
1310                 die(_("a branch is expected, got '%s'"), ref);
1311         }
1312         if (branch_info->commit)
1313                 die(_("a branch is expected, got commit '%s'"), branch_info->name);
1314         /*
1315          * This case should never happen because we already die() on
1316          * non-commit, but just in case.
1317          */
1318         die(_("a branch is expected, got '%s'"), branch_info->name);
1319 }
1320
1321 static void die_if_some_operation_in_progress(void)
1322 {
1323         struct wt_status_state state;
1324
1325         memset(&state, 0, sizeof(state));
1326         wt_status_get_state(the_repository, &state, 0);
1327
1328         if (state.merge_in_progress)
1329                 die(_("cannot switch branch while merging\n"
1330                       "Consider \"git merge --quit\" "
1331                       "or \"git worktree add\"."));
1332         if (state.am_in_progress)
1333                 die(_("cannot switch branch in the middle of an am session\n"
1334                       "Consider \"git am --quit\" "
1335                       "or \"git worktree add\"."));
1336         if (state.rebase_interactive_in_progress || state.rebase_in_progress)
1337                 die(_("cannot switch branch while rebasing\n"
1338                       "Consider \"git rebase --quit\" "
1339                       "or \"git worktree add\"."));
1340         if (state.cherry_pick_in_progress)
1341                 die(_("cannot switch branch while cherry-picking\n"
1342                       "Consider \"git cherry-pick --quit\" "
1343                       "or \"git worktree add\"."));
1344         if (state.revert_in_progress)
1345                 die(_("cannot switch branch while reverting\n"
1346                       "Consider \"git revert --quit\" "
1347                       "or \"git worktree add\"."));
1348         if (state.bisect_in_progress)
1349                 warning(_("you are switching branch while bisecting"));
1350 }
1351
1352 static int checkout_branch(struct checkout_opts *opts,
1353                            struct branch_info *new_branch_info)
1354 {
1355         if (opts->pathspec.nr)
1356                 die(_("paths cannot be used with switching branches"));
1357
1358         if (opts->patch_mode)
1359                 die(_("'%s' cannot be used with switching branches"),
1360                     "--patch");
1361
1362         if (opts->overlay_mode != -1)
1363                 die(_("'%s' cannot be used with switching branches"),
1364                     "--[no]-overlay");
1365
1366         if (opts->writeout_stage)
1367                 die(_("'%s' cannot be used with switching branches"),
1368                     "--ours/--theirs");
1369
1370         if (opts->force && opts->merge)
1371                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1372
1373         if (opts->discard_changes && opts->merge)
1374                 die(_("'%s' cannot be used with '%s'"), "--discard-changes", "--merge");
1375
1376         if (opts->force_detach && opts->new_branch)
1377                 die(_("'%s' cannot be used with '%s'"),
1378                     "--detach", "-b/-B/--orphan");
1379
1380         if (opts->new_orphan_branch) {
1381                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1382                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1383                 if (opts->orphan_from_empty_tree && new_branch_info->name)
1384                         die(_("'%s' cannot take <start-point>"), "--orphan");
1385         } else if (opts->force_detach) {
1386                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1387                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1388         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1389                 opts->track = git_branch_track;
1390
1391         if (new_branch_info->name && !new_branch_info->commit)
1392                 die(_("Cannot switch branch to a non-commit '%s'"),
1393                     new_branch_info->name);
1394
1395         if (!opts->switch_branch_doing_nothing_is_ok &&
1396             !new_branch_info->name &&
1397             !opts->new_branch &&
1398             !opts->force_detach)
1399                 die(_("missing branch or commit argument"));
1400
1401         if (!opts->implicit_detach &&
1402             !opts->force_detach &&
1403             !opts->new_branch &&
1404             !opts->new_branch_force &&
1405             new_branch_info->name &&
1406             !new_branch_info->path)
1407                 die_expecting_a_branch(new_branch_info);
1408
1409         if (!opts->can_switch_when_in_progress)
1410                 die_if_some_operation_in_progress();
1411
1412         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1413             !opts->ignore_other_worktrees) {
1414                 int flag;
1415                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1416                 if (head_ref &&
1417                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1418                         die_if_checked_out(new_branch_info->path, 1);
1419                 free(head_ref);
1420         }
1421
1422         if (!new_branch_info->commit && opts->new_branch) {
1423                 struct object_id rev;
1424                 int flag;
1425
1426                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1427                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1428                         return switch_unborn_to_new_branch(opts);
1429         }
1430         return switch_branches(opts, new_branch_info);
1431 }
1432
1433 static struct option *add_common_options(struct checkout_opts *opts,
1434                                          struct option *prevopts)
1435 {
1436         struct option options[] = {
1437                 OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1438                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1439                             "checkout", "control recursive updating of submodules",
1440                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1441                 OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1442                 OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1443                 OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1444                            N_("conflict style (merge or diff3)")),
1445                 OPT_END()
1446         };
1447         struct option *newopts = parse_options_concat(prevopts, options);
1448         free(prevopts);
1449         return newopts;
1450 }
1451
1452 static struct option *add_common_switch_branch_options(
1453         struct checkout_opts *opts, struct option *prevopts)
1454 {
1455         struct option options[] = {
1456                 OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1457                 OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1458                         BRANCH_TRACK_EXPLICIT),
1459                 OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1460                            PARSE_OPT_NOCOMPLETE),
1461                 OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1462                 OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1463                            N_("update ignored files (default)"),
1464                            PARSE_OPT_NOCOMPLETE),
1465                 OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1466                          N_("do not check if another worktree is holding the given ref")),
1467                 OPT_END()
1468         };
1469         struct option *newopts = parse_options_concat(prevopts, options);
1470         free(prevopts);
1471         return newopts;
1472 }
1473
1474 static struct option *add_checkout_path_options(struct checkout_opts *opts,
1475                                                 struct option *prevopts)
1476 {
1477         struct option options[] = {
1478                 OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1479                               N_("checkout our version for unmerged files"),
1480                               2, PARSE_OPT_NONEG),
1481                 OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1482                               N_("checkout their version for unmerged files"),
1483                               3, PARSE_OPT_NONEG),
1484                 OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1485                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1486                          N_("do not limit pathspecs to sparse entries only")),
1487                 OPT_PATHSPEC_FROM_FILE(&opts->pathspec_from_file),
1488                 OPT_PATHSPEC_FILE_NUL(&opts->pathspec_file_nul),
1489                 OPT_END()
1490         };
1491         struct option *newopts = parse_options_concat(prevopts, options);
1492         free(prevopts);
1493         return newopts;
1494 }
1495
1496 static int checkout_main(int argc, const char **argv, const char *prefix,
1497                          struct checkout_opts *opts, struct option *options,
1498                          const char * const usagestr[])
1499 {
1500         struct branch_info new_branch_info;
1501         int dwim_remotes_matched = 0;
1502         int parseopt_flags = 0;
1503
1504         memset(&new_branch_info, 0, sizeof(new_branch_info));
1505         opts->overwrite_ignore = 1;
1506         opts->prefix = prefix;
1507         opts->show_progress = -1;
1508
1509         git_config(git_checkout_config, opts);
1510
1511         opts->track = BRANCH_TRACK_UNSPECIFIED;
1512
1513         if (!opts->accept_pathspec && !opts->accept_ref)
1514                 BUG("make up your mind, you need to take _something_");
1515         if (opts->accept_pathspec && opts->accept_ref)
1516                 parseopt_flags = PARSE_OPT_KEEP_DASHDASH;
1517
1518         argc = parse_options(argc, argv, prefix, options,
1519                              usagestr, parseopt_flags);
1520
1521         if (opts->show_progress < 0) {
1522                 if (opts->quiet)
1523                         opts->show_progress = 0;
1524                 else
1525                         opts->show_progress = isatty(2);
1526         }
1527
1528         if (opts->conflict_style) {
1529                 opts->merge = 1; /* implied */
1530                 git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1531         }
1532         if (opts->force) {
1533                 opts->discard_changes = 1;
1534                 opts->ignore_unmerged_opt = "--force";
1535                 opts->ignore_unmerged = 1;
1536         }
1537
1538         if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1539                 die(_("-b, -B and --orphan are mutually exclusive"));
1540
1541         if (opts->overlay_mode == 1 && opts->patch_mode)
1542                 die(_("-p and --overlay are mutually exclusive"));
1543
1544         if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
1545                 if (opts->checkout_index < 0)
1546                         opts->checkout_index = 0;
1547                 if (opts->checkout_worktree < 0)
1548                         opts->checkout_worktree = 0;
1549         } else {
1550                 if (opts->checkout_index < 0)
1551                         opts->checkout_index = -opts->checkout_index - 1;
1552                 if (opts->checkout_worktree < 0)
1553                         opts->checkout_worktree = -opts->checkout_worktree - 1;
1554         }
1555         if (opts->checkout_index < 0 || opts->checkout_worktree < 0)
1556                 BUG("these flags should be non-negative by now");
1557         /*
1558          * convenient shortcut: "git restore --staged" equals
1559          * "git restore --staged --source HEAD"
1560          */
1561         if (!opts->from_treeish && opts->checkout_index && !opts->checkout_worktree)
1562                 opts->from_treeish = "HEAD";
1563
1564         /*
1565          * From here on, new_branch will contain the branch to be checked out,
1566          * and new_branch_force and new_orphan_branch will tell us which one of
1567          * -b/-B/--orphan is being used.
1568          */
1569         if (opts->new_branch_force)
1570                 opts->new_branch = opts->new_branch_force;
1571
1572         if (opts->new_orphan_branch)
1573                 opts->new_branch = opts->new_orphan_branch;
1574
1575         /* --track without -b/-B/--orphan should DWIM */
1576         if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1577                 const char *argv0 = argv[0];
1578                 if (!argc || !strcmp(argv0, "--"))
1579                         die(_("--track needs a branch name"));
1580                 skip_prefix(argv0, "refs/", &argv0);
1581                 skip_prefix(argv0, "remotes/", &argv0);
1582                 argv0 = strchr(argv0, '/');
1583                 if (!argv0 || !argv0[1])
1584                         die(_("missing branch name; try -b"));
1585                 opts->new_branch = argv0 + 1;
1586         }
1587
1588         /*
1589          * Extract branch name from command line arguments, so
1590          * all that is left is pathspecs.
1591          *
1592          * Handle
1593          *
1594          *  1) git checkout <tree> -- [<paths>]
1595          *  2) git checkout -- [<paths>]
1596          *  3) git checkout <something> [<paths>]
1597          *
1598          * including "last branch" syntax and DWIM-ery for names of
1599          * remote branches, erroring out for invalid or ambiguous cases.
1600          */
1601         if (argc && opts->accept_ref) {
1602                 struct object_id rev;
1603                 int dwim_ok =
1604                         !opts->patch_mode &&
1605                         opts->dwim_new_local_branch &&
1606                         opts->track == BRANCH_TRACK_UNSPECIFIED &&
1607                         !opts->new_branch;
1608                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1609                                              &new_branch_info, opts, &rev,
1610                                              &dwim_remotes_matched);
1611                 argv += n;
1612                 argc -= n;
1613         } else if (!opts->accept_ref && opts->from_treeish) {
1614                 struct object_id rev;
1615
1616                 if (get_oid_mb(opts->from_treeish, &rev))
1617                         die(_("could not resolve %s"), opts->from_treeish);
1618
1619                 setup_new_branch_info_and_source_tree(&new_branch_info,
1620                                                       opts, &rev,
1621                                                       opts->from_treeish);
1622
1623                 if (!opts->source_tree)
1624                         die(_("reference is not a tree: %s"), opts->from_treeish);
1625         }
1626
1627         if (argc) {
1628                 parse_pathspec(&opts->pathspec, 0,
1629                                opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1630                                prefix, argv);
1631
1632                 if (!opts->pathspec.nr)
1633                         die(_("invalid path specification"));
1634
1635                 /*
1636                  * Try to give more helpful suggestion.
1637                  * new_branch && argc > 1 will be caught later.
1638                  */
1639                 if (opts->new_branch && argc == 1)
1640                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1641                                 argv[0], opts->new_branch);
1642
1643                 if (opts->force_detach)
1644                         die(_("git checkout: --detach does not take a path argument '%s'"),
1645                             argv[0]);
1646         }
1647
1648         if (opts->pathspec_from_file) {
1649                 if (opts->pathspec.nr)
1650                         die(_("--pathspec-from-file is incompatible with pathspec arguments"));
1651
1652                 if (opts->force_detach)
1653                         die(_("--pathspec-from-file is incompatible with --detach"));
1654
1655                 if (opts->patch_mode)
1656                         die(_("--pathspec-from-file is incompatible with --patch"));
1657
1658                 parse_pathspec_file(&opts->pathspec, 0,
1659                                     0,
1660                                     prefix, opts->pathspec_from_file, opts->pathspec_file_nul);
1661         } else if (opts->pathspec_file_nul) {
1662                 die(_("--pathspec-file-nul requires --pathspec-from-file"));
1663         }
1664
1665         if (opts->pathspec.nr) {
1666                 if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1667                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1668                               "checking out of the index."));
1669         } else {
1670                 if (opts->accept_pathspec && !opts->empty_pathspec_ok &&
1671                     !opts->patch_mode)  /* patch mode is special */
1672                         die(_("you must specify path(s) to restore"));
1673         }
1674
1675         if (opts->new_branch) {
1676                 struct strbuf buf = STRBUF_INIT;
1677
1678                 if (opts->new_branch_force)
1679                         opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1680                 else
1681                         opts->branch_exists =
1682                                 validate_new_branchname(opts->new_branch, &buf, 0);
1683                 strbuf_release(&buf);
1684         }
1685
1686         UNLEAK(opts);
1687         if (opts->patch_mode || opts->pathspec.nr) {
1688                 int ret = checkout_paths(opts, new_branch_info.name);
1689                 if (ret && dwim_remotes_matched > 1 &&
1690                     advice_checkout_ambiguous_remote_branch_name)
1691                         advise(_("'%s' matched more than one remote tracking branch.\n"
1692                                  "We found %d remotes with a reference that matched. So we fell back\n"
1693                                  "on trying to resolve the argument as a path, but failed there too!\n"
1694                                  "\n"
1695                                  "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1696                                  "you can do so by fully qualifying the name with the --track option:\n"
1697                                  "\n"
1698                                  "    git checkout --track origin/<name>\n"
1699                                  "\n"
1700                                  "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1701                                  "one remote, e.g. the 'origin' remote, consider setting\n"
1702                                  "checkout.defaultRemote=origin in your config."),
1703                                argv[0],
1704                                dwim_remotes_matched);
1705                 return ret;
1706         } else {
1707                 return checkout_branch(opts, &new_branch_info);
1708         }
1709 }
1710
1711 int cmd_checkout(int argc, const char **argv, const char *prefix)
1712 {
1713         struct checkout_opts opts;
1714         struct option *options;
1715         struct option checkout_options[] = {
1716                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1717                            N_("create and checkout a new branch")),
1718                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1719                            N_("create/reset and checkout a branch")),
1720                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1721                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1722                          N_("second guess 'git checkout <no-such-branch>' (default)")),
1723                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1724                 OPT_END()
1725         };
1726         int ret;
1727
1728         memset(&opts, 0, sizeof(opts));
1729         opts.dwim_new_local_branch = 1;
1730         opts.switch_branch_doing_nothing_is_ok = 1;
1731         opts.only_merge_on_switching_branches = 0;
1732         opts.accept_ref = 1;
1733         opts.accept_pathspec = 1;
1734         opts.implicit_detach = 1;
1735         opts.can_switch_when_in_progress = 1;
1736         opts.orphan_from_empty_tree = 0;
1737         opts.empty_pathspec_ok = 1;
1738         opts.overlay_mode = -1;
1739         opts.checkout_index = -2;    /* default on */
1740         opts.checkout_worktree = -2; /* default on */
1741
1742         if (argc == 3 && !strcmp(argv[1], "-b")) {
1743                 /*
1744                  * User ran 'git checkout -b <branch>' and expects
1745                  * the same behavior as 'git switch -c <branch>'.
1746                  */
1747                 opts.switch_branch_doing_nothing_is_ok = 0;
1748                 opts.only_merge_on_switching_branches = 1;
1749         }
1750
1751         options = parse_options_dup(checkout_options);
1752         options = add_common_options(&opts, options);
1753         options = add_common_switch_branch_options(&opts, options);
1754         options = add_checkout_path_options(&opts, options);
1755
1756         ret = checkout_main(argc, argv, prefix, &opts,
1757                             options, checkout_usage);
1758         FREE_AND_NULL(options);
1759         return ret;
1760 }
1761
1762 int cmd_switch(int argc, const char **argv, const char *prefix)
1763 {
1764         struct checkout_opts opts;
1765         struct option *options = NULL;
1766         struct option switch_options[] = {
1767                 OPT_STRING('c', "create", &opts.new_branch, N_("branch"),
1768                            N_("create and switch to a new branch")),
1769                 OPT_STRING('C', "force-create", &opts.new_branch_force, N_("branch"),
1770                            N_("create/reset and switch to a branch")),
1771                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1772                          N_("second guess 'git switch <no-such-branch>'")),
1773                 OPT_BOOL(0, "discard-changes", &opts.discard_changes,
1774                          N_("throw away local modifications")),
1775                 OPT_END()
1776         };
1777         int ret;
1778
1779         memset(&opts, 0, sizeof(opts));
1780         opts.dwim_new_local_branch = 1;
1781         opts.accept_ref = 1;
1782         opts.accept_pathspec = 0;
1783         opts.switch_branch_doing_nothing_is_ok = 0;
1784         opts.only_merge_on_switching_branches = 1;
1785         opts.implicit_detach = 0;
1786         opts.can_switch_when_in_progress = 0;
1787         opts.orphan_from_empty_tree = 1;
1788         opts.overlay_mode = -1;
1789
1790         options = parse_options_dup(switch_options);
1791         options = add_common_options(&opts, options);
1792         options = add_common_switch_branch_options(&opts, options);
1793
1794         ret = checkout_main(argc, argv, prefix, &opts,
1795                             options, switch_branch_usage);
1796         FREE_AND_NULL(options);
1797         return ret;
1798 }
1799
1800 int cmd_restore(int argc, const char **argv, const char *prefix)
1801 {
1802         struct checkout_opts opts;
1803         struct option *options;
1804         struct option restore_options[] = {
1805                 OPT_STRING('s', "source", &opts.from_treeish, "<tree-ish>",
1806                            N_("which tree-ish to checkout from")),
1807                 OPT_BOOL('S', "staged", &opts.checkout_index,
1808                            N_("restore the index")),
1809                 OPT_BOOL('W', "worktree", &opts.checkout_worktree,
1810                            N_("restore the working tree (default)")),
1811                 OPT_BOOL(0, "ignore-unmerged", &opts.ignore_unmerged,
1812                          N_("ignore unmerged entries")),
1813                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
1814                 OPT_END()
1815         };
1816         int ret;
1817
1818         memset(&opts, 0, sizeof(opts));
1819         opts.accept_ref = 0;
1820         opts.accept_pathspec = 1;
1821         opts.empty_pathspec_ok = 0;
1822         opts.overlay_mode = 0;
1823         opts.checkout_index = -1;    /* default off */
1824         opts.checkout_worktree = -2; /* default on */
1825         opts.ignore_unmerged_opt = "--ignore-unmerged";
1826
1827         options = parse_options_dup(restore_options);
1828         options = add_common_options(&opts, options);
1829         options = add_checkout_path_options(&opts, options);
1830
1831         ret = checkout_main(argc, argv, prefix, &opts,
1832                             options, restore_usage);
1833         FREE_AND_NULL(options);
1834         return ret;
1835 }