builtin/checkout.c

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