git.oblomov.eu Git - git/blob - builtin/checkout.c

   1 #include "builtin.h"
   2 #include "lockfile.h"
   3 #include "parse-options.h"
   4 #include "refs.h"
   5 #include "commit.h"
   6 #include "tree.h"
   7 #include "tree-walk.h"
   8 #include "cache-tree.h"
   9 #include "unpack-trees.h"
  10 #include "dir.h"
  11 #include "run-command.h"
  12 #include "merge-recursive.h"
  13 #include "branch.h"
  14 #include "diff.h"
  15 #include "revision.h"
  16 #include "remote.h"
  17 #include "blob.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "resolve-undo.h"
  21 #include "submodule.h"
  22 #include "argv-array.h"
  23
  24 static const char * const checkout_usage[] = {
  25         N_("git checkout [options] <branch>"),
  26         N_("git checkout [options] [<branch>] -- <file>..."),
  27         NULL,
  28 };
  29
  30 struct checkout_opts {
  31         int patch_mode;
  32         int quiet;
  33         int merge;
  34         int force;
  35         int force_detach;
  36         int writeout_stage;
  37         int overwrite_ignore;
  38         int ignore_skipworktree;
  39
  40         const char *new_branch;
  41         const char *new_branch_force;
  42         const char *new_orphan_branch;
  43         int new_branch_log;
  44         enum branch_track track;
  45         struct diff_options diff_options;
  46
  47         int branch_exists;
  48         const char *prefix;
  49         struct pathspec pathspec;
  50         struct tree *source_tree;
  51 };
  52
  53 static int post_checkout_hook(struct commit *old, struct commit *new,
  54                               int changed)
  55 {
  56         return run_hook_le(NULL, "post-checkout",
  57                            sha1_to_hex(old ? old->object.sha1 : null_sha1),
  58                            sha1_to_hex(new ? new->object.sha1 : null_sha1),
  59                            changed ? "1" : "0", NULL);
  60         /* "new" can be NULL when checking out from the index before
  61            a commit exists. */
  62
  63 }
  64
  65 static int update_some(const unsigned char *sha1, const char *base, int baselen,
  66                 const char *pathname, unsigned mode, int stage, void *context)
  67 {
  68         int len;
  69         struct cache_entry *ce;
  70
  71         if (S_ISDIR(mode))
  72                 return READ_TREE_RECURSIVE;
  73
  74         len = baselen + strlen(pathname);
  75         ce = xcalloc(1, cache_entry_size(len));
  76         hashcpy(ce->sha1, sha1);
  77         memcpy(ce->name, base, baselen);
  78         memcpy(ce->name + baselen, pathname, len - baselen);
  79         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  80         ce->ce_namelen = len;
  81         ce->ce_mode = create_ce_mode(mode);
  82         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
  83         return 0;
  84 }
  85
  86 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
  87 {
  88         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
  89
  90         /* update the index with the given tree's info
  91          * for all args, expanding wildcards, and exit
  92          * with any non-zero return code.
  93          */
  94         return 0;
  95 }
  96
  97 static int skip_same_name(const struct cache_entry *ce, int pos)
  98 {
  99         while (++pos < active_nr &&
 100                !strcmp(active_cache[pos]->name, ce->name))
 101                 ; /* skip */
 102         return pos;
 103 }
 104
 105 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 106 {
 107         while (pos < active_nr &&
 108                !strcmp(active_cache[pos]->name, ce->name)) {
 109                 if (ce_stage(active_cache[pos]) == stage)
 110                         return 0;
 111                 pos++;
 112         }
 113         if (stage == 2)
 114                 return error(_("path '%s' does not have our version"), ce->name);
 115         else
 116                 return error(_("path '%s' does not have their version"), ce->name);
 117 }
 118
 119 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 120 {
 121         unsigned seen = 0;
 122         const char *name = ce->name;
 123
 124         while (pos < active_nr) {
 125                 ce = active_cache[pos];
 126                 if (strcmp(name, ce->name))
 127                         break;
 128                 seen |= (1 << ce_stage(ce));
 129                 pos++;
 130         }
 131         if ((stages & seen) != stages)
 132                 return error(_("path '%s' does not have all necessary versions"),
 133                              name);
 134         return 0;
 135 }
 136
 137 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 138                           struct checkout *state)
 139 {
 140         while (pos < active_nr &&
 141                !strcmp(active_cache[pos]->name, ce->name)) {
 142                 if (ce_stage(active_cache[pos]) == stage)
 143                         return checkout_entry(active_cache[pos], state, NULL);
 144                 pos++;
 145         }
 146         if (stage == 2)
 147                 return error(_("path '%s' does not have our version"), ce->name);
 148         else
 149                 return error(_("path '%s' does not have their version"), ce->name);
 150 }
 151
 152 static int checkout_merged(int pos, struct checkout *state)
 153 {
 154         struct cache_entry *ce = active_cache[pos];
 155         const char *path = ce->name;
 156         mmfile_t ancestor, ours, theirs;
 157         int status;
 158         unsigned char sha1[20];
 159         mmbuffer_t result_buf;
 160         unsigned char threeway[3][20];
 161         unsigned mode = 0;
 162
 163         memset(threeway, 0, sizeof(threeway));
 164         while (pos < active_nr) {
 165                 int stage;
 166                 stage = ce_stage(ce);
 167                 if (!stage || strcmp(path, ce->name))
 168                         break;
 169                 hashcpy(threeway[stage - 1], ce->sha1);
 170                 if (stage == 2)
 171                         mode = create_ce_mode(ce->ce_mode);
 172                 pos++;
 173                 ce = active_cache[pos];
 174         }
 175         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
 176                 return error(_("path '%s' does not have necessary versions"), path);
 177
 178         read_mmblob(&ancestor, threeway[0]);
 179         read_mmblob(&ours, threeway[1]);
 180         read_mmblob(&theirs, threeway[2]);
 181
 182         /*
 183          * NEEDSWORK: re-create conflicts from merges with
 184          * merge.renormalize set, too
 185          */
 186         status = ll_merge(&result_buf, path, &ancestor, "base",
 187                           &ours, "ours", &theirs, "theirs", NULL);
 188         free(ancestor.ptr);
 189         free(ours.ptr);
 190         free(theirs.ptr);
 191         if (status < 0 || !result_buf.ptr) {
 192                 free(result_buf.ptr);
 193                 return error(_("path '%s': cannot merge"), path);
 194         }
 195
 196         /*
 197          * NEEDSWORK:
 198          * There is absolutely no reason to write this as a blob object
 199          * and create a phony cache entry just to leak.  This hack is
 200          * primarily to get to the write_entry() machinery that massages
 201          * the contents to work-tree format and writes out which only
 202          * allows it for a cache entry.  The code in write_entry() needs
 203          * to be refactored to allow us to feed a <buffer, size, mode>
 204          * instead of a cache entry.  Such a refactoring would help
 205          * merge_recursive as well (it also writes the merge result to the
 206          * object database even when it may contain conflicts).
 207          */
 208         if (write_sha1_file(result_buf.ptr, result_buf.size,
 209                             blob_type, sha1))
 210                 die(_("Unable to add merge result for '%s'"), path);
 211         ce = make_cache_entry(mode, sha1, path, 2, 0);
 212         if (!ce)
 213                 die(_("make_cache_entry failed for path '%s'"), path);
 214         status = checkout_entry(ce, state, NULL);
 215         return status;
 216 }
 217
 218 static int checkout_paths(const struct checkout_opts *opts,
 219                           const char *revision)
 220 {
 221         int pos;
 222         struct checkout state;
 223         static char *ps_matched;
 224         unsigned char rev[20];
 225         int flag;
 226         struct commit *head;
 227         int errs = 0;
 228         struct lock_file *lock_file;
 229
 230         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 231                 die(_("'%s' cannot be used with updating paths"), "--track");
 232
 233         if (opts->new_branch_log)
 234                 die(_("'%s' cannot be used with updating paths"), "-l");
 235
 236         if (opts->force && opts->patch_mode)
 237                 die(_("'%s' cannot be used with updating paths"), "-f");
 238
 239         if (opts->force_detach)
 240                 die(_("'%s' cannot be used with updating paths"), "--detach");
 241
 242         if (opts->merge && opts->patch_mode)
 243                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 244
 245         if (opts->force && opts->merge)
 246                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 247
 248         if (opts->new_branch)
 249                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 250                     opts->new_branch);
 251
 252         if (opts->patch_mode)
 253                 return run_add_interactive(revision, "--patch=checkout",
 254                                            &opts->pathspec);
 255
 256         lock_file = xcalloc(1, sizeof(struct lock_file));
 257
 258         hold_locked_index(lock_file, 1);
 259         if (read_cache_preload(&opts->pathspec) < 0)
 260                 return error(_("corrupt index file"));
 261
 262         if (opts->source_tree)
 263                 read_tree_some(opts->source_tree, &opts->pathspec);
 264
 265         ps_matched = xcalloc(1, opts->pathspec.nr);
 266
 267         /*
 268          * Make sure all pathspecs participated in locating the paths
 269          * to be checked out.
 270          */
 271         for (pos = 0; pos < active_nr; pos++) {
 272                 struct cache_entry *ce = active_cache[pos];
 273                 ce->ce_flags &= ~CE_MATCHED;
 274                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 275                         continue;
 276                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 277                         /*
 278                          * "git checkout tree-ish -- path", but this entry
 279                          * is in the original index; it will not be checked
 280                          * out to the working tree and it does not matter
 281                          * if pathspec matched this entry.  We will not do
 282                          * anything to this entry at all.
 283                          */
 284                         continue;
 285                 /*
 286                  * Either this entry came from the tree-ish we are
 287                  * checking the paths out of, or we are checking out
 288                  * of the index.
 289                  *
 290                  * If it comes from the tree-ish, we already know it
 291                  * matches the pathspec and could just stamp
 292                  * CE_MATCHED to it from update_some(). But we still
 293                  * need ps_matched and read_tree_recursive (and
 294                  * eventually tree_entry_interesting) cannot fill
 295                  * ps_matched yet. Once it can, we can avoid calling
 296                  * match_pathspec() for _all_ entries when
 297                  * opts->source_tree != NULL.
 298                  */
 299                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
 300                         ce->ce_flags |= CE_MATCHED;
 301         }
 302
 303         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 304                 free(ps_matched);
 305                 return 1;
 306         }
 307         free(ps_matched);
 308
 309         /* "checkout -m path" to recreate conflicted state */
 310         if (opts->merge)
 311                 unmerge_marked_index(&the_index);
 312
 313         /* Any unmerged paths? */
 314         for (pos = 0; pos < active_nr; pos++) {
 315                 const struct cache_entry *ce = active_cache[pos];
 316                 if (ce->ce_flags & CE_MATCHED) {
 317                         if (!ce_stage(ce))
 318                                 continue;
 319                         if (opts->force) {
 320                                 warning(_("path '%s' is unmerged"), ce->name);
 321                         } else if (opts->writeout_stage) {
 322                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 323                         } else if (opts->merge) {
 324                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 325                         } else {
 326                                 errs = 1;
 327                                 error(_("path '%s' is unmerged"), ce->name);
 328                         }
 329                         pos = skip_same_name(ce, pos) - 1;
 330                 }
 331         }
 332         if (errs)
 333                 return 1;
 334
 335         /* Now we are committed to check them out */
 336         memset(&state, 0, sizeof(state));
 337         state.force = 1;
 338         state.refresh_cache = 1;
 339         state.istate = &the_index;
 340         for (pos = 0; pos < active_nr; pos++) {
 341                 struct cache_entry *ce = active_cache[pos];
 342                 if (ce->ce_flags & CE_MATCHED) {
 343                         if (!ce_stage(ce)) {
 344                                 errs |= checkout_entry(ce, &state, NULL);
 345                                 continue;
 346                         }
 347                         if (opts->writeout_stage)
 348                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 349                         else if (opts->merge)
 350                                 errs |= checkout_merged(pos, &state);
 351                         pos = skip_same_name(ce, pos) - 1;
 352                 }
 353         }
 354
 355         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 356                 die(_("unable to write new index file"));
 357
 358         read_ref_full("HEAD", 0, rev, &flag);
 359         head = lookup_commit_reference_gently(rev, 1);
 360
 361         errs |= post_checkout_hook(head, head, 0);
 362         return errs;
 363 }
 364
 365 static void show_local_changes(struct object *head,
 366                                const struct diff_options *opts)
 367 {
 368         struct rev_info rev;
 369         /* I think we want full paths, even if we're in a subdirectory. */
 370         init_revisions(&rev, NULL);
 371         rev.diffopt.flags = opts->flags;
 372         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 373         diff_setup_done(&rev.diffopt);
 374         add_pending_object(&rev, head, NULL);
 375         run_diff_index(&rev, 0);
 376 }
 377
 378 static void describe_detached_head(const char *msg, struct commit *commit)
 379 {
 380         struct strbuf sb = STRBUF_INIT;
 381         if (!parse_commit(commit))
 382                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 383         fprintf(stderr, "%s %s... %s\n", msg,
 384                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 385         strbuf_release(&sb);
 386 }
 387
 388 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 389                       int worktree, int *writeout_error)
 390 {
 391         struct unpack_trees_options opts;
 392         struct tree_desc tree_desc;
 393
 394         memset(&opts, 0, sizeof(opts));
 395         opts.head_idx = -1;
 396         opts.update = worktree;
 397         opts.skip_unmerged = !worktree;
 398         opts.reset = 1;
 399         opts.merge = 1;
 400         opts.fn = oneway_merge;
 401         opts.verbose_update = !o->quiet && isatty(2);
 402         opts.src_index = &the_index;
 403         opts.dst_index = &the_index;
 404         parse_tree(tree);
 405         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 406         switch (unpack_trees(1, &tree_desc, &opts)) {
 407         case -2:
 408                 *writeout_error = 1;
 409                 /*
 410                  * We return 0 nevertheless, as the index is all right
 411                  * and more importantly we have made best efforts to
 412                  * update paths in the work tree, and we cannot revert
 413                  * them.
 414                  */
 415         case 0:
 416                 return 0;
 417         default:
 418                 return 128;
 419         }
 420 }
 421
 422 struct branch_info {
 423         const char *name; /* The short name used */
 424         const char *path; /* The full name of a real branch */
 425         struct commit *commit; /* The named commit */
 426 };
 427
 428 static void setup_branch_path(struct branch_info *branch)
 429 {
 430         struct strbuf buf = STRBUF_INIT;
 431
 432         strbuf_branchname(&buf, branch->name);
 433         if (strcmp(buf.buf, branch->name))
 434                 branch->name = xstrdup(buf.buf);
 435         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 436         branch->path = strbuf_detach(&buf, NULL);
 437 }
 438
 439 static int merge_working_tree(const struct checkout_opts *opts,
 440                               struct branch_info *old,
 441                               struct branch_info *new,
 442                               int *writeout_error)
 443 {
 444         int ret;
 445         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 446
 447         hold_locked_index(lock_file, 1);
 448         if (read_cache_preload(NULL) < 0)
 449                 return error(_("corrupt index file"));
 450
 451         resolve_undo_clear();
 452         if (opts->force) {
 453                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 454                 if (ret)
 455                         return ret;
 456         } else {
 457                 struct tree_desc trees[2];
 458                 struct tree *tree;
 459                 struct unpack_trees_options topts;
 460
 461                 memset(&topts, 0, sizeof(topts));
 462                 topts.head_idx = -1;
 463                 topts.src_index = &the_index;
 464                 topts.dst_index = &the_index;
 465
 466                 setup_unpack_trees_porcelain(&topts, "checkout");
 467
 468                 refresh_cache(REFRESH_QUIET);
 469
 470                 if (unmerged_cache()) {
 471                         error(_("you need to resolve your current index first"));
 472                         return 1;
 473                 }
 474
 475                 /* 2-way merge to the new branch */
 476                 topts.initial_checkout = is_cache_unborn();
 477                 topts.update = 1;
 478                 topts.merge = 1;
 479                 topts.gently = opts->merge && old->commit;
 480                 topts.verbose_update = !opts->quiet && isatty(2);
 481                 topts.fn = twoway_merge;
 482                 if (opts->overwrite_ignore) {
 483                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 484                         topts.dir->flags |= DIR_SHOW_IGNORED;
 485                         setup_standard_excludes(topts.dir);
 486                 }
 487                 tree = parse_tree_indirect(old->commit ?
 488                                            old->commit->object.sha1 :
 489                                            EMPTY_TREE_SHA1_BIN);
 490                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 491                 tree = parse_tree_indirect(new->commit->object.sha1);
 492                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 493
 494                 ret = unpack_trees(2, trees, &topts);
 495                 if (ret == -1) {
 496                         /*
 497                          * Unpack couldn't do a trivial merge; either
 498                          * give up or do a real merge, depending on
 499                          * whether the merge flag was used.
 500                          */
 501                         struct tree *result;
 502                         struct tree *work;
 503                         struct merge_options o;
 504                         if (!opts->merge)
 505                                 return 1;
 506
 507                         /*
 508                          * Without old->commit, the below is the same as
 509                          * the two-tree unpack we already tried and failed.
 510                          */
 511                         if (!old->commit)
 512                                 return 1;
 513
 514                         /* Do more real merge */
 515
 516                         /*
 517                          * We update the index fully, then write the
 518                          * tree from the index, then merge the new
 519                          * branch with the current tree, with the old
 520                          * branch as the base. Then we reset the index
 521                          * (but not the working tree) to the new
 522                          * branch, leaving the working tree as the
 523                          * merged version, but skipping unmerged
 524                          * entries in the index.
 525                          */
 526
 527                         add_files_to_cache(NULL, NULL, 0);
 528                         /*
 529                          * NEEDSWORK: carrying over local changes
 530                          * when branches have different end-of-line
 531                          * normalization (or clean+smudge rules) is
 532                          * a pain; plumb in an option to set
 533                          * o.renormalize?
 534                          */
 535                         init_merge_options(&o);
 536                         o.verbosity = 0;
 537                         work = write_tree_from_memory(&o);
 538
 539                         ret = reset_tree(new->commit->tree, opts, 1,
 540                                          writeout_error);
 541                         if (ret)
 542                                 return ret;
 543                         o.ancestor = old->name;
 544                         o.branch1 = new->name;
 545                         o.branch2 = "local";
 546                         merge_trees(&o, new->commit->tree, work,
 547                                 old->commit->tree, &result);
 548                         ret = reset_tree(new->commit->tree, opts, 0,
 549                                          writeout_error);
 550                         if (ret)
 551                                 return ret;
 552                 }
 553         }
 554
 555         if (!active_cache_tree)
 556                 active_cache_tree = cache_tree();
 557
 558         if (!cache_tree_fully_valid(active_cache_tree))
 559                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 560
 561         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 562                 die(_("unable to write new index file"));
 563
 564         if (!opts->force && !opts->quiet)
 565                 show_local_changes(&new->commit->object, &opts->diff_options);
 566
 567         return 0;
 568 }
 569
 570 static void report_tracking(struct branch_info *new)
 571 {
 572         struct strbuf sb = STRBUF_INIT;
 573         struct branch *branch = branch_get(new->name);
 574
 575         if (!format_tracking_info(branch, &sb))
 576                 return;
 577         fputs(sb.buf, stdout);
 578         strbuf_release(&sb);
 579 }
 580
 581 static void update_refs_for_switch(const struct checkout_opts *opts,
 582                                    struct branch_info *old,
 583                                    struct branch_info *new)
 584 {
 585         struct strbuf msg = STRBUF_INIT;
 586         const char *old_desc, *reflog_msg;
 587         if (opts->new_branch) {
 588                 if (opts->new_orphan_branch) {
 589                         if (opts->new_branch_log && !log_all_ref_updates) {
 590                                 int temp;
 591                                 struct strbuf log_file = STRBUF_INIT;
 592                                 int ret;
 593                                 const char *ref_name;
 594
 595                                 ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 596                                 temp = log_all_ref_updates;
 597                                 log_all_ref_updates = 1;
 598                                 ret = log_ref_setup(ref_name, &log_file);
 599                                 log_all_ref_updates = temp;
 600                                 strbuf_release(&log_file);
 601                                 if (ret) {
 602                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
 603                                             opts->new_orphan_branch);
 604                                         return;
 605                                 }
 606                         }
 607                 }
 608                 else
 609                         create_branch(old->name, opts->new_branch, new->name,
 610                                       opts->new_branch_force ? 1 : 0,
 611                                       opts->new_branch_log,
 612                                       opts->new_branch_force ? 1 : 0,
 613                                       opts->quiet,
 614                                       opts->track);
 615                 new->name = opts->new_branch;
 616                 setup_branch_path(new);
 617         }
 618
 619         old_desc = old->name;
 620         if (!old_desc && old->commit)
 621                 old_desc = sha1_to_hex(old->commit->object.sha1);
 622
 623         reflog_msg = getenv("GIT_REFLOG_ACTION");
 624         if (!reflog_msg)
 625                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 626                         old_desc ? old_desc : "(invalid)", new->name);
 627         else
 628                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 629
 630         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 631                 /* Nothing to do. */
 632         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 633                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 634                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 635                 if (!opts->quiet) {
 636                         if (old->path && advice_detached_head)
 637                                 detach_advice(new->name);
 638                         describe_detached_head(_("HEAD is now at"), new->commit);
 639                 }
 640         } else if (new->path) { /* Switch branches. */
 641                 create_symref("HEAD", new->path, msg.buf);
 642                 if (!opts->quiet) {
 643                         if (old->path && !strcmp(new->path, old->path)) {
 644                                 if (opts->new_branch_force)
 645                                         fprintf(stderr, _("Reset branch '%s'\n"),
 646                                                 new->name);
 647                                 else
 648                                         fprintf(stderr, _("Already on '%s'\n"),
 649                                                 new->name);
 650                         } else if (opts->new_branch) {
 651                                 if (opts->branch_exists)
 652                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 653                                 else
 654                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 655                         } else {
 656                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 657                                         new->name);
 658                         }
 659                 }
 660                 if (old->path && old->name) {
 661                         if (!ref_exists(old->path) && reflog_exists(old->path))
 662                                 delete_reflog(old->path);
 663                 }
 664         }
 665         remove_branch_state();
 666         strbuf_release(&msg);
 667         if (!opts->quiet &&
 668             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 669                 report_tracking(new);
 670 }
 671
 672 static int add_pending_uninteresting_ref(const char *refname,
 673                                          const unsigned char *sha1,
 674                                          int flags, void *cb_data)
 675 {
 676         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
 677         return 0;
 678 }
 679
 680 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 681 {
 682         strbuf_addstr(sb, "  ");
 683         strbuf_addstr(sb,
 684                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 685         strbuf_addch(sb, ' ');
 686         if (!parse_commit(commit))
 687                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 688         strbuf_addch(sb, '\n');
 689 }
 690
 691 #define ORPHAN_CUTOFF 4
 692 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 693 {
 694         struct commit *c, *last = NULL;
 695         struct strbuf sb = STRBUF_INIT;
 696         int lost = 0;
 697         while ((c = get_revision(revs)) != NULL) {
 698                 if (lost < ORPHAN_CUTOFF)
 699                         describe_one_orphan(&sb, c);
 700                 last = c;
 701                 lost++;
 702         }
 703         if (ORPHAN_CUTOFF < lost) {
 704                 int more = lost - ORPHAN_CUTOFF;
 705                 if (more == 1)
 706                         describe_one_orphan(&sb, last);
 707                 else
 708                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 709         }
 710
 711         fprintf(stderr,
 712                 Q_(
 713                 /* The singular version */
 714                 "Warning: you are leaving %d commit behind, "
 715                 "not connected to\n"
 716                 "any of your branches:\n\n"
 717                 "%s\n",
 718                 /* The plural version */
 719                 "Warning: you are leaving %d commits behind, "
 720                 "not connected to\n"
 721                 "any of your branches:\n\n"
 722                 "%s\n",
 723                 /* Give ngettext() the count */
 724                 lost),
 725                 lost,
 726                 sb.buf);
 727         strbuf_release(&sb);
 728
 729         if (advice_detached_head)
 730                 fprintf(stderr,
 731                         _(
 732                         "If you want to keep them by creating a new branch, "
 733                         "this may be a good time\nto do so with:\n\n"
 734                         " git branch new_branch_name %s\n\n"),
 735                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 736 }
 737
 738 /*
 739  * We are about to leave commit that was at the tip of a detached
 740  * HEAD.  If it is not reachable from any ref, this is the last chance
 741  * for the user to do so without resorting to reflog.
 742  */
 743 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 744 {
 745         struct rev_info revs;
 746         struct object *object = &old->object;
 747         struct object_array refs;
 748
 749         init_revisions(&revs, NULL);
 750         setup_revisions(0, NULL, &revs, NULL);
 751
 752         object->flags &= ~UNINTERESTING;
 753         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 754
 755         for_each_ref(add_pending_uninteresting_ref, &revs);
 756         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 757
 758         refs = revs.pending;
 759         revs.leak_pending = 1;
 760
 761         if (prepare_revision_walk(&revs))
 762                 die(_("internal error in revision walk"));
 763         if (!(old->object.flags & UNINTERESTING))
 764                 suggest_reattach(old, &revs);
 765         else
 766                 describe_detached_head(_("Previous HEAD position was"), old);
 767
 768         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 769         free(refs.objects);
 770 }
 771
 772 static int switch_branches(const struct checkout_opts *opts,
 773                            struct branch_info *new)
 774 {
 775         int ret = 0;
 776         struct branch_info old;
 777         void *path_to_free;
 778         unsigned char rev[20];
 779         int flag, writeout_error = 0;
 780         memset(&old, 0, sizeof(old));
 781         old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 782         old.commit = lookup_commit_reference_gently(rev, 1);
 783         if (!(flag & REF_ISSYMREF))
 784                 old.path = NULL;
 785
 786         if (old.path)
 787                 skip_prefix(old.path, "refs/heads/", &old.name);
 788
 789         if (!new->name) {
 790                 new->name = "HEAD";
 791                 new->commit = old.commit;
 792                 if (!new->commit)
 793                         die(_("You are on a branch yet to be born"));
 794                 parse_commit_or_die(new->commit);
 795         }
 796
 797         ret = merge_working_tree(opts, &old, new, &writeout_error);
 798         if (ret) {
 799                 free(path_to_free);
 800                 return ret;
 801         }
 802
 803         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 804                 orphaned_commit_warning(old.commit, new->commit);
 805
 806         update_refs_for_switch(opts, &old, new);
 807
 808         ret = post_checkout_hook(old.commit, new->commit, 1);
 809         free(path_to_free);
 810         return ret || writeout_error;
 811 }
 812
 813 static int git_checkout_config(const char *var, const char *value, void *cb)
 814 {
 815         if (!strcmp(var, "diff.ignoresubmodules")) {
 816                 struct checkout_opts *opts = cb;
 817                 handle_ignore_submodules_arg(&opts->diff_options, value);
 818                 return 0;
 819         }
 820
 821         if (starts_with(var, "submodule."))
 822                 return parse_submodule_config_option(var, value);
 823
 824         return git_xmerge_config(var, value, NULL);
 825 }
 826
 827 struct tracking_name_data {
 828         /* const */ char *src_ref;
 829         char *dst_ref;
 830         unsigned char *dst_sha1;
 831         int unique;
 832 };
 833
 834 static int check_tracking_name(struct remote *remote, void *cb_data)
 835 {
 836         struct tracking_name_data *cb = cb_data;
 837         struct refspec query;
 838         memset(&query, 0, sizeof(struct refspec));
 839         query.src = cb->src_ref;
 840         if (remote_find_tracking(remote, &query) ||
 841             get_sha1(query.dst, cb->dst_sha1)) {
 842                 free(query.dst);
 843                 return 0;
 844         }
 845         if (cb->dst_ref) {
 846                 free(query.dst);
 847                 cb->unique = 0;
 848                 return 0;
 849         }
 850         cb->dst_ref = query.dst;
 851         return 0;
 852 }
 853
 854 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 855 {
 856         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 857         char src_ref[PATH_MAX];
 858         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 859         cb_data.src_ref = src_ref;
 860         cb_data.dst_sha1 = sha1;
 861         for_each_remote(check_tracking_name, &cb_data);
 862         if (cb_data.unique)
 863                 return cb_data.dst_ref;
 864         free(cb_data.dst_ref);
 865         return NULL;
 866 }
 867
 868 static int parse_branchname_arg(int argc, const char **argv,
 869                                 int dwim_new_local_branch_ok,
 870                                 struct branch_info *new,
 871                                 struct tree **source_tree,
 872                                 unsigned char rev[20],
 873                                 const char **new_branch)
 874 {
 875         int argcount = 0;
 876         unsigned char branch_rev[20];
 877         const char *arg;
 878         int dash_dash_pos;
 879         int has_dash_dash = 0;
 880         int i;
 881
 882         /*
 883          * case 1: git checkout <ref> -- [<paths>]
 884          *
 885          *   <ref> must be a valid tree, everything after the '--' must be
 886          *   a path.
 887          *
 888          * case 2: git checkout -- [<paths>]
 889          *
 890          *   everything after the '--' must be paths.
 891          *
 892          * case 3: git checkout <something> [--]
 893          *
 894          *   (a) If <something> is a commit, that is to
 895          *       switch to the branch or detach HEAD at it.  As a special case,
 896          *       if <something> is A...B (missing A or B means HEAD but you can
 897          *       omit at most one side), and if there is a unique merge base
 898          *       between A and B, A...B names that merge base.
 899          *
 900          *   (b) If <something> is _not_ a commit, either "--" is present
 901          *       or <something> is not a path, no -t or -b was given, and
 902          *       and there is a tracking branch whose name is <something>
 903          *       in one and only one remote, then this is a short-hand to
 904          *       fork local <something> from that remote-tracking branch.
 905          *
 906          *   (c) Otherwise, if "--" is present, treat it like case (1).
 907          *
 908          *   (d) Otherwise :
 909          *       - if it's a reference, treat it like case (1)
 910          *       - else if it's a path, treat it like case (2)
 911          *       - else: fail.
 912          *
 913          * case 4: git checkout <something> <paths>
 914          *
 915          *   The first argument must not be ambiguous.
 916          *   - If it's *only* a reference, treat it like case (1).
 917          *   - If it's only a path, treat it like case (2).
 918          *   - else: fail.
 919          *
 920          */
 921         if (!argc)
 922                 return 0;
 923
 924         arg = argv[0];
 925         dash_dash_pos = -1;
 926         for (i = 0; i < argc; i++) {
 927                 if (!strcmp(argv[i], "--")) {
 928                         dash_dash_pos = i;
 929                         break;
 930                 }
 931         }
 932         if (dash_dash_pos == 0)
 933                 return 1; /* case (2) */
 934         else if (dash_dash_pos == 1)
 935                 has_dash_dash = 1; /* case (3) or (1) */
 936         else if (dash_dash_pos >= 2)
 937                 die(_("only one reference expected, %d given."), dash_dash_pos);
 938
 939         if (!strcmp(arg, "-"))
 940                 arg = "@{-1}";
 941
 942         if (get_sha1_mb(arg, rev)) {
 943                 /*
 944                  * Either case (3) or (4), with <something> not being
 945                  * a commit, or an attempt to use case (1) with an
 946                  * invalid ref.
 947                  *
 948                  * It's likely an error, but we need to find out if
 949                  * we should auto-create the branch, case (3).(b).
 950                  */
 951                 int recover_with_dwim = dwim_new_local_branch_ok;
 952
 953                 if (check_filename(NULL, arg) && !has_dash_dash)
 954                         recover_with_dwim = 0;
 955                 /*
 956                  * Accept "git checkout foo" and "git checkout foo --"
 957                  * as candidates for dwim.
 958                  */
 959                 if (!(argc == 1 && !has_dash_dash) &&
 960                     !(argc == 2 && has_dash_dash))
 961                         recover_with_dwim = 0;
 962
 963                 if (recover_with_dwim) {
 964                         const char *remote = unique_tracking_name(arg, rev);
 965                         if (remote) {
 966                                 *new_branch = arg;
 967                                 arg = remote;
 968                                 /* DWIMmed to create local branch, case (3).(b) */
 969                         } else {
 970                                 recover_with_dwim = 0;
 971                         }
 972                 }
 973
 974                 if (!recover_with_dwim) {
 975                         if (has_dash_dash)
 976                                 die(_("invalid reference: %s"), arg);
 977                         return argcount;
 978                 }
 979         }
 980
 981         /* we can't end up being in (2) anymore, eat the argument */
 982         argcount++;
 983         argv++;
 984         argc--;
 985
 986         new->name = arg;
 987         setup_branch_path(new);
 988
 989         if (!check_refname_format(new->path, 0) &&
 990             !read_ref(new->path, branch_rev))
 991                 hashcpy(rev, branch_rev);
 992         else
 993                 new->path = NULL; /* not an existing branch */
 994
 995         new->commit = lookup_commit_reference_gently(rev, 1);
 996         if (!new->commit) {
 997                 /* not a commit */
 998                 *source_tree = parse_tree_indirect(rev);
 999         } else {
1000                 parse_commit_or_die(new->commit);
1001                 *source_tree = new->commit->tree;
1002         }
1003
1004         if (!*source_tree)                   /* case (1): want a tree */
1005                 die(_("reference is not a tree: %s"), arg);
1006         if (!has_dash_dash) {/* case (3).(d) -> (1) */
1007                 /*
1008                  * Do not complain the most common case
1009                  *      git checkout branch
1010                  * even if there happen to be a file called 'branch';
1011                  * it would be extremely annoying.
1012                  */
1013                 if (argc)
1014                         verify_non_filename(NULL, arg);
1015         } else {
1016                 argcount++;
1017                 argv++;
1018                 argc--;
1019         }
1020
1021         return argcount;
1022 }
1023
1024 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1025 {
1026         int status;
1027         struct strbuf branch_ref = STRBUF_INIT;
1028
1029         if (!opts->new_branch)
1030                 die(_("You are on a branch yet to be born"));
1031         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1032         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1033         strbuf_release(&branch_ref);
1034         if (!opts->quiet)
1035                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1036                         opts->new_branch);
1037         return status;
1038 }
1039
1040 static int checkout_branch(struct checkout_opts *opts,
1041                            struct branch_info *new)
1042 {
1043         if (opts->pathspec.nr)
1044                 die(_("paths cannot be used with switching branches"));
1045
1046         if (opts->patch_mode)
1047                 die(_("'%s' cannot be used with switching branches"),
1048                     "--patch");
1049
1050         if (opts->writeout_stage)
1051                 die(_("'%s' cannot be used with switching branches"),
1052                     "--ours/--theirs");
1053
1054         if (opts->force && opts->merge)
1055                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1056
1057         if (opts->force_detach && opts->new_branch)
1058                 die(_("'%s' cannot be used with '%s'"),
1059                     "--detach", "-b/-B/--orphan");
1060
1061         if (opts->new_orphan_branch) {
1062                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1063                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1064         } else if (opts->force_detach) {
1065                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1066                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1067         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1068                 opts->track = git_branch_track;
1069
1070         if (new->name && !new->commit)
1071                 die(_("Cannot switch branch to a non-commit '%s'"),
1072                     new->name);
1073
1074         if (!new->commit && opts->new_branch) {
1075                 unsigned char rev[20];
1076                 int flag;
1077
1078                 if (!read_ref_full("HEAD", 0, rev, &flag) &&
1079                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1080                         return switch_unborn_to_new_branch(opts);
1081         }
1082         return switch_branches(opts, new);
1083 }
1084
1085 int cmd_checkout(int argc, const char **argv, const char *prefix)
1086 {
1087         struct checkout_opts opts;
1088         struct branch_info new;
1089         char *conflict_style = NULL;
1090         int dwim_new_local_branch = 1;
1091         struct option options[] = {
1092                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1093                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1094                            N_("create and checkout a new branch")),
1095                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1096                            N_("create/reset and checkout a branch")),
1097                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1098                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1099                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1100                         BRANCH_TRACK_EXPLICIT),
1101                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1102                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1103                             2),
1104                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1105                             3),
1106                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1107                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1108                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1109                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1110                            N_("conflict style (merge or diff3)")),
1111                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1112                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1113                          N_("do not limit pathspecs to sparse entries only")),
1114                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1115                                 N_("second guess 'git checkout no-such-branch'")),
1116                 OPT_END(),
1117         };
1118
1119         memset(&opts, 0, sizeof(opts));
1120         memset(&new, 0, sizeof(new));
1121         opts.overwrite_ignore = 1;
1122         opts.prefix = prefix;
1123
1124         gitmodules_config();
1125         git_config(git_checkout_config, &opts);
1126
1127         opts.track = BRANCH_TRACK_UNSPECIFIED;
1128
1129         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1130                              PARSE_OPT_KEEP_DASHDASH);
1131
1132         if (conflict_style) {
1133                 opts.merge = 1; /* implied */
1134                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1135         }
1136
1137         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1138                 die(_("-b, -B and --orphan are mutually exclusive"));
1139
1140         /*
1141          * From here on, new_branch will contain the branch to be checked out,
1142          * and new_branch_force and new_orphan_branch will tell us which one of
1143          * -b/-B/--orphan is being used.
1144          */
1145         if (opts.new_branch_force)
1146                 opts.new_branch = opts.new_branch_force;
1147
1148         if (opts.new_orphan_branch)
1149                 opts.new_branch = opts.new_orphan_branch;
1150
1151         /* --track without -b/-B/--orphan should DWIM */
1152         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1153                 const char *argv0 = argv[0];
1154                 if (!argc || !strcmp(argv0, "--"))
1155                         die (_("--track needs a branch name"));
1156                 skip_prefix(argv0, "refs/", &argv0);
1157                 skip_prefix(argv0, "remotes/", &argv0);
1158                 argv0 = strchr(argv0, '/');
1159                 if (!argv0 || !argv0[1])
1160                         die (_("Missing branch name; try -b"));
1161                 opts.new_branch = argv0 + 1;
1162         }
1163
1164         /*
1165          * Extract branch name from command line arguments, so
1166          * all that is left is pathspecs.
1167          *
1168          * Handle
1169          *
1170          *  1) git checkout <tree> -- [<paths>]
1171          *  2) git checkout -- [<paths>]
1172          *  3) git checkout <something> [<paths>]
1173          *
1174          * including "last branch" syntax and DWIM-ery for names of
1175          * remote branches, erroring out for invalid or ambiguous cases.
1176          */
1177         if (argc) {
1178                 unsigned char rev[20];
1179                 int dwim_ok =
1180                         !opts.patch_mode &&
1181                         dwim_new_local_branch &&
1182                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1183                         !opts.new_branch;
1184                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1185                                              &new, &opts.source_tree,
1186                                              rev, &opts.new_branch);
1187                 argv += n;
1188                 argc -= n;
1189         }
1190
1191         if (argc) {
1192                 parse_pathspec(&opts.pathspec, 0,
1193                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1194                                prefix, argv);
1195
1196                 if (!opts.pathspec.nr)
1197                         die(_("invalid path specification"));
1198
1199                 /*
1200                  * Try to give more helpful suggestion.
1201                  * new_branch && argc > 1 will be caught later.
1202                  */
1203                 if (opts.new_branch && argc == 1)
1204                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1205                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1206                             opts.new_branch, argv[0]);
1207
1208                 if (opts.force_detach)
1209                         die(_("git checkout: --detach does not take a path argument '%s'"),
1210                             argv[0]);
1211
1212                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1213                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1214                               "checking out of the index."));
1215         }
1216
1217         if (opts.new_branch) {
1218                 struct strbuf buf = STRBUF_INIT;
1219
1220                 opts.branch_exists =
1221                         validate_new_branchname(opts.new_branch, &buf,
1222                                                 !!opts.new_branch_force,
1223                                                 !!opts.new_branch_force);
1224
1225                 strbuf_release(&buf);
1226         }
1227
1228         if (opts.patch_mode || opts.pathspec.nr)
1229                 return checkout_paths(&opts, new.name);
1230         else
1231                 return checkout_branch(&opts, &new);
1232 }