git.oblomov.eu Git - git/blob - 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
  22 static const char * const checkout_usage[] = {
  23         "git checkout [options] <branch>",
  24         "git checkout [options] [<branch>] -- <file>...",
  25         NULL,
  26 };
  27
  28 struct checkout_opts {
  29         int quiet;
  30         int merge;
  31         int force;
  32         int writeout_stage;
  33         int writeout_error;
  34
  35         const char *new_branch;
  36         int new_branch_log;
  37         enum branch_track track;
  38 };
  39
  40 static int post_checkout_hook(struct commit *old, struct commit *new,
  41                               int changed)
  42 {
  43         return run_hook(NULL, "post-checkout",
  44                         sha1_to_hex(old ? old->object.sha1 : null_sha1),
  45                         sha1_to_hex(new ? new->object.sha1 : null_sha1),
  46                         changed ? "1" : "0", NULL);
  47         /* "new" can be NULL when checking out from the index before
  48            a commit exists. */
  49
  50 }
  51
  52 static int update_some(const unsigned char *sha1, const char *base, int baselen,
  53                 const char *pathname, unsigned mode, int stage, void *context)
  54 {
  55         int len;
  56         struct cache_entry *ce;
  57
  58         if (S_ISDIR(mode))
  59                 return READ_TREE_RECURSIVE;
  60
  61         len = baselen + strlen(pathname);
  62         ce = xcalloc(1, cache_entry_size(len));
  63         hashcpy(ce->sha1, sha1);
  64         memcpy(ce->name, base, baselen);
  65         memcpy(ce->name + baselen, pathname, len - baselen);
  66         ce->ce_flags = create_ce_flags(len, 0);
  67         ce->ce_mode = create_ce_mode(mode);
  68         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
  69         return 0;
  70 }
  71
  72 static int read_tree_some(struct tree *tree, const char **pathspec)
  73 {
  74         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
  75
  76         /* update the index with the given tree's info
  77          * for all args, expanding wildcards, and exit
  78          * with any non-zero return code.
  79          */
  80         return 0;
  81 }
  82
  83 static int skip_same_name(struct cache_entry *ce, int pos)
  84 {
  85         while (++pos < active_nr &&
  86                !strcmp(active_cache[pos]->name, ce->name))
  87                 ; /* skip */
  88         return pos;
  89 }
  90
  91 static int check_stage(int stage, struct cache_entry *ce, int pos)
  92 {
  93         while (pos < active_nr &&
  94                !strcmp(active_cache[pos]->name, ce->name)) {
  95                 if (ce_stage(active_cache[pos]) == stage)
  96                         return 0;
  97                 pos++;
  98         }
  99         return error("path '%s' does not have %s version",
 100                      ce->name,
 101                      (stage == 2) ? "our" : "their");
 102 }
 103
 104 static int check_all_stages(struct cache_entry *ce, int pos)
 105 {
 106         if (ce_stage(ce) != 1 ||
 107             active_nr <= pos + 2 ||
 108             strcmp(active_cache[pos+1]->name, ce->name) ||
 109             ce_stage(active_cache[pos+1]) != 2 ||
 110             strcmp(active_cache[pos+2]->name, ce->name) ||
 111             ce_stage(active_cache[pos+2]) != 3)
 112                 return error("path '%s' does not have all three versions",
 113                              ce->name);
 114         return 0;
 115 }
 116
 117 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 118                           struct checkout *state)
 119 {
 120         while (pos < active_nr &&
 121                !strcmp(active_cache[pos]->name, ce->name)) {
 122                 if (ce_stage(active_cache[pos]) == stage)
 123                         return checkout_entry(active_cache[pos], state, NULL);
 124                 pos++;
 125         }
 126         return error("path '%s' does not have %s version",
 127                      ce->name,
 128                      (stage == 2) ? "our" : "their");
 129 }
 130
 131 /* NEEDSWORK: share with merge-recursive */
 132 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 133 {
 134         unsigned long size;
 135         enum object_type type;
 136
 137         if (!hashcmp(sha1, null_sha1)) {
 138                 mm->ptr = xstrdup("");
 139                 mm->size = 0;
 140                 return;
 141         }
 142
 143         mm->ptr = read_sha1_file(sha1, &type, &size);
 144         if (!mm->ptr || type != OBJ_BLOB)
 145                 die("unable to read blob object %s", sha1_to_hex(sha1));
 146         mm->size = size;
 147 }
 148
 149 static int checkout_merged(int pos, struct checkout *state)
 150 {
 151         struct cache_entry *ce = active_cache[pos];
 152         const char *path = ce->name;
 153         mmfile_t ancestor, ours, theirs;
 154         int status;
 155         unsigned char sha1[20];
 156         mmbuffer_t result_buf;
 157
 158         if (ce_stage(ce) != 1 ||
 159             active_nr <= pos + 2 ||
 160             strcmp(active_cache[pos+1]->name, path) ||
 161             ce_stage(active_cache[pos+1]) != 2 ||
 162             strcmp(active_cache[pos+2]->name, path) ||
 163             ce_stage(active_cache[pos+2]) != 3)
 164                 return error("path '%s' does not have all 3 versions", path);
 165
 166         fill_mm(active_cache[pos]->sha1, &ancestor);
 167         fill_mm(active_cache[pos+1]->sha1, &ours);
 168         fill_mm(active_cache[pos+2]->sha1, &theirs);
 169
 170         status = ll_merge(&result_buf, path, &ancestor,
 171                           &ours, "ours", &theirs, "theirs", 1);
 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                           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                 match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
 233         }
 234
 235         if (report_path_error(ps_matched, pathspec, 0))
 236                 return 1;
 237
 238         /* Any unmerged paths? */
 239         for (pos = 0; pos < active_nr; pos++) {
 240                 struct cache_entry *ce = active_cache[pos];
 241                 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 242                         if (!ce_stage(ce))
 243                                 continue;
 244                         if (opts->force) {
 245                                 warning("path '%s' is unmerged", ce->name);
 246                         } else if (stage) {
 247                                 errs |= check_stage(stage, ce, pos);
 248                         } else if (opts->merge) {
 249                                 errs |= check_all_stages(ce, pos);
 250                         } else {
 251                                 errs = 1;
 252                                 error("path '%s' is unmerged", ce->name);
 253                         }
 254                         pos = skip_same_name(ce, pos) - 1;
 255                 }
 256         }
 257         if (errs)
 258                 return 1;
 259
 260         /* Now we are committed to check them out */
 261         memset(&state, 0, sizeof(state));
 262         state.force = 1;
 263         state.refresh_cache = 1;
 264         for (pos = 0; pos < active_nr; pos++) {
 265                 struct cache_entry *ce = active_cache[pos];
 266                 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 267                         if (!ce_stage(ce)) {
 268                                 errs |= checkout_entry(ce, &state, NULL);
 269                                 continue;
 270                         }
 271                         if (stage)
 272                                 errs |= checkout_stage(stage, ce, pos, &state);
 273                         else if (merge)
 274                                 errs |= checkout_merged(pos, &state);
 275                         pos = skip_same_name(ce, pos) - 1;
 276                 }
 277         }
 278
 279         if (write_cache(newfd, active_cache, active_nr) ||
 280             commit_locked_index(lock_file))
 281                 die("unable to write new index file");
 282
 283         resolve_ref("HEAD", rev, 0, &flag);
 284         head = lookup_commit_reference_gently(rev, 1);
 285
 286         errs |= post_checkout_hook(head, head, 0);
 287         return errs;
 288 }
 289
 290 static void show_local_changes(struct object *head)
 291 {
 292         struct rev_info rev;
 293         /* I think we want full paths, even if we're in a subdirectory. */
 294         init_revisions(&rev, NULL);
 295         rev.abbrev = 0;
 296         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 297         if (diff_setup_done(&rev.diffopt) < 0)
 298                 die("diff_setup_done failed");
 299         add_pending_object(&rev, head, NULL);
 300         run_diff_index(&rev, 0);
 301 }
 302
 303 static void describe_detached_head(char *msg, struct commit *commit)
 304 {
 305         struct strbuf sb = STRBUF_INIT;
 306         struct pretty_print_context ctx = {0};
 307         parse_commit(commit);
 308         pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, &ctx);
 309         fprintf(stderr, "%s %s... %s\n", msg,
 310                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 311         strbuf_release(&sb);
 312 }
 313
 314 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
 315 {
 316         struct unpack_trees_options opts;
 317         struct tree_desc tree_desc;
 318
 319         memset(&opts, 0, sizeof(opts));
 320         opts.head_idx = -1;
 321         opts.update = worktree;
 322         opts.skip_unmerged = !worktree;
 323         opts.reset = 1;
 324         opts.merge = 1;
 325         opts.fn = oneway_merge;
 326         opts.verbose_update = !o->quiet;
 327         opts.src_index = &the_index;
 328         opts.dst_index = &the_index;
 329         parse_tree(tree);
 330         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 331         switch (unpack_trees(1, &tree_desc, &opts)) {
 332         case -2:
 333                 o->writeout_error = 1;
 334                 /*
 335                  * We return 0 nevertheless, as the index is all right
 336                  * and more importantly we have made best efforts to
 337                  * update paths in the work tree, and we cannot revert
 338                  * them.
 339                  */
 340         case 0:
 341                 return 0;
 342         default:
 343                 return 128;
 344         }
 345 }
 346
 347 struct branch_info {
 348         const char *name; /* The short name used */
 349         const char *path; /* The full name of a real branch */
 350         struct commit *commit; /* The named commit */
 351 };
 352
 353 static void setup_branch_path(struct branch_info *branch)
 354 {
 355         struct strbuf buf = STRBUF_INIT;
 356
 357         strbuf_branchname(&buf, branch->name);
 358         if (strcmp(buf.buf, branch->name))
 359                 branch->name = xstrdup(buf.buf);
 360         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 361         branch->path = strbuf_detach(&buf, NULL);
 362 }
 363
 364 static int merge_working_tree(struct checkout_opts *opts,
 365                               struct branch_info *old, struct branch_info *new)
 366 {
 367         int ret;
 368         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 369         int newfd = hold_locked_index(lock_file, 1);
 370
 371         if (read_cache_preload(NULL) < 0)
 372                 return error("corrupt index file");
 373
 374         resolve_undo_clear();
 375         if (opts->force) {
 376                 ret = reset_tree(new->commit->tree, opts, 1);
 377                 if (ret)
 378                         return ret;
 379         } else {
 380                 struct tree_desc trees[2];
 381                 struct tree *tree;
 382                 struct unpack_trees_options topts;
 383
 384                 memset(&topts, 0, sizeof(topts));
 385                 topts.head_idx = -1;
 386                 topts.src_index = &the_index;
 387                 topts.dst_index = &the_index;
 388
 389                 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
 390
 391                 refresh_cache(REFRESH_QUIET);
 392
 393                 if (unmerged_cache()) {
 394                         error("you need to resolve your current index first");
 395                         return 1;
 396                 }
 397
 398                 /* 2-way merge to the new branch */
 399                 topts.initial_checkout = is_cache_unborn();
 400                 topts.update = 1;
 401                 topts.merge = 1;
 402                 topts.gently = opts->merge;
 403                 topts.verbose_update = !opts->quiet;
 404                 topts.fn = twoway_merge;
 405                 topts.dir = xcalloc(1, sizeof(*topts.dir));
 406                 topts.dir->flags |= DIR_SHOW_IGNORED;
 407                 topts.dir->exclude_per_dir = ".gitignore";
 408                 tree = parse_tree_indirect(old->commit ?
 409                                            old->commit->object.sha1 :
 410                                            (unsigned char *)EMPTY_TREE_SHA1_BIN);
 411                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 412                 tree = parse_tree_indirect(new->commit->object.sha1);
 413                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 414
 415                 ret = unpack_trees(2, trees, &topts);
 416                 if (ret == -1) {
 417                         /*
 418                          * Unpack couldn't do a trivial merge; either
 419                          * give up or do a real merge, depending on
 420                          * whether the merge flag was used.
 421                          */
 422                         struct tree *result;
 423                         struct tree *work;
 424                         struct merge_options o;
 425                         if (!opts->merge)
 426                                 return 1;
 427                         parse_commit(old->commit);
 428
 429                         /* Do more real merge */
 430
 431                         /*
 432                          * We update the index fully, then write the
 433                          * tree from the index, then merge the new
 434                          * branch with the current tree, with the old
 435                          * branch as the base. Then we reset the index
 436                          * (but not the working tree) to the new
 437                          * branch, leaving the working tree as the
 438                          * merged version, but skipping unmerged
 439                          * entries in the index.
 440                          */
 441
 442                         add_files_to_cache(NULL, NULL, 0);
 443                         init_merge_options(&o);
 444                         o.verbosity = 0;
 445                         work = write_tree_from_memory(&o);
 446
 447                         ret = reset_tree(new->commit->tree, opts, 1);
 448                         if (ret)
 449                                 return ret;
 450                         o.branch1 = new->name;
 451                         o.branch2 = "local";
 452                         merge_trees(&o, new->commit->tree, work,
 453                                 old->commit->tree, &result);
 454                         ret = reset_tree(new->commit->tree, opts, 0);
 455                         if (ret)
 456                                 return ret;
 457                 }
 458         }
 459
 460         if (write_cache(newfd, active_cache, active_nr) ||
 461             commit_locked_index(lock_file))
 462                 die("unable to write new index file");
 463
 464         if (!opts->force && !opts->quiet)
 465                 show_local_changes(&new->commit->object);
 466
 467         return 0;
 468 }
 469
 470 static void report_tracking(struct branch_info *new)
 471 {
 472         struct strbuf sb = STRBUF_INIT;
 473         struct branch *branch = branch_get(new->name);
 474
 475         if (!format_tracking_info(branch, &sb))
 476                 return;
 477         fputs(sb.buf, stdout);
 478         strbuf_release(&sb);
 479 }
 480
 481 static void update_refs_for_switch(struct checkout_opts *opts,
 482                                    struct branch_info *old,
 483                                    struct branch_info *new)
 484 {
 485         struct strbuf msg = STRBUF_INIT;
 486         const char *old_desc;
 487         if (opts->new_branch) {
 488                 create_branch(old->name, opts->new_branch, new->name, 0,
 489                               opts->new_branch_log, opts->track);
 490                 new->name = opts->new_branch;
 491                 setup_branch_path(new);
 492         }
 493
 494         old_desc = old->name;
 495         if (!old_desc && old->commit)
 496                 old_desc = sha1_to_hex(old->commit->object.sha1);
 497         strbuf_addf(&msg, "checkout: moving from %s to %s",
 498                     old_desc ? old_desc : "(invalid)", new->name);
 499
 500         if (new->path) {
 501                 create_symref("HEAD", new->path, msg.buf);
 502                 if (!opts->quiet) {
 503                         if (old->path && !strcmp(new->path, old->path))
 504                                 fprintf(stderr, "Already on '%s'\n",
 505                                         new->name);
 506                         else
 507                                 fprintf(stderr, "Switched to%s branch '%s'\n",
 508                                         opts->new_branch ? " a new" : "",
 509                                         new->name);
 510                 }
 511         } else if (strcmp(new->name, "HEAD")) {
 512                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 513                            REF_NODEREF, DIE_ON_ERR);
 514                 if (!opts->quiet) {
 515                         if (old->path)
 516                                 fprintf(stderr, "Note: moving to '%s' which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n  git checkout -b <new_branch_name>\n", new->name);
 517                         describe_detached_head("HEAD is now at", new->commit);
 518                 }
 519         }
 520         remove_branch_state();
 521         strbuf_release(&msg);
 522         if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
 523                 report_tracking(new);
 524 }
 525
 526 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 527 {
 528         int ret = 0;
 529         struct branch_info old;
 530         unsigned char rev[20];
 531         int flag;
 532         memset(&old, 0, sizeof(old));
 533         old.path = resolve_ref("HEAD", rev, 0, &flag);
 534         old.commit = lookup_commit_reference_gently(rev, 1);
 535         if (!(flag & REF_ISSYMREF))
 536                 old.path = NULL;
 537
 538         if (old.path && !prefixcmp(old.path, "refs/heads/"))
 539                 old.name = old.path + strlen("refs/heads/");
 540
 541         if (!new->name) {
 542                 new->name = "HEAD";
 543                 new->commit = old.commit;
 544                 if (!new->commit)
 545                         die("You are on a branch yet to be born");
 546                 parse_commit(new->commit);
 547         }
 548
 549         ret = merge_working_tree(opts, &old, new);
 550         if (ret)
 551                 return ret;
 552
 553         /*
 554          * If we were on a detached HEAD, but have now moved to
 555          * a new commit, we want to mention the old commit once more
 556          * to remind the user that it might be lost.
 557          */
 558         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 559                 describe_detached_head("Previous HEAD position was", old.commit);
 560
 561         update_refs_for_switch(opts, &old, new);
 562
 563         ret = post_checkout_hook(old.commit, new->commit, 1);
 564         return ret || opts->writeout_error;
 565 }
 566
 567 static int git_checkout_config(const char *var, const char *value, void *cb)
 568 {
 569         return git_xmerge_config(var, value, cb);
 570 }
 571
 572 static int interactive_checkout(const char *revision, const char **pathspec,
 573                                 struct checkout_opts *opts)
 574 {
 575         return run_add_interactive(revision, "--patch=checkout", pathspec);
 576 }
 577
 578 struct tracking_name_data {
 579         const char *name;
 580         char *remote;
 581         int unique;
 582 };
 583
 584 static int check_tracking_name(const char *refname, const unsigned char *sha1,
 585                                int flags, void *cb_data)
 586 {
 587         struct tracking_name_data *cb = cb_data;
 588         const char *slash;
 589
 590         if (prefixcmp(refname, "refs/remotes/"))
 591                 return 0;
 592         slash = strchr(refname + 13, '/');
 593         if (!slash || strcmp(slash + 1, cb->name))
 594                 return 0;
 595         if (cb->remote) {
 596                 cb->unique = 0;
 597                 return 0;
 598         }
 599         cb->remote = xstrdup(refname);
 600         return 0;
 601 }
 602
 603 static const char *unique_tracking_name(const char *name)
 604 {
 605         struct tracking_name_data cb_data = { name, NULL, 1 };
 606         for_each_ref(check_tracking_name, &cb_data);
 607         if (cb_data.unique)
 608                 return cb_data.remote;
 609         free(cb_data.remote);
 610         return NULL;
 611 }
 612
 613 int cmd_checkout(int argc, const char **argv, const char *prefix)
 614 {
 615         struct checkout_opts opts;
 616         unsigned char rev[20];
 617         const char *arg;
 618         struct branch_info new;
 619         struct tree *source_tree = NULL;
 620         char *conflict_style = NULL;
 621         int patch_mode = 0;
 622         int dwim_new_local_branch = 1;
 623         struct option options[] = {
 624                 OPT__QUIET(&opts.quiet),
 625                 OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
 626                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
 627                 OPT_SET_INT('t', "track",  &opts.track, "track",
 628                         BRANCH_TRACK_EXPLICIT),
 629                 OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
 630                             2),
 631                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
 632                             3),
 633                 OPT_BOOLEAN('f', "force", &opts.force, "force"),
 634                 OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
 635                 OPT_STRING(0, "conflict", &conflict_style, "style",
 636                            "conflict style (merge or diff3)"),
 637                 OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
 638                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
 639                   "second guess 'git checkout no-such-branch'",
 640                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
 641                 OPT_END(),
 642         };
 643         int has_dash_dash;
 644
 645         memset(&opts, 0, sizeof(opts));
 646         memset(&new, 0, sizeof(new));
 647
 648         git_config(git_checkout_config, NULL);
 649
 650         opts.track = BRANCH_TRACK_UNSPECIFIED;
 651
 652         argc = parse_options(argc, argv, prefix, options, checkout_usage,
 653                              PARSE_OPT_KEEP_DASHDASH);
 654
 655         if (patch_mode && (opts.track > 0 || opts.new_branch
 656                            || opts.new_branch_log || opts.merge || opts.force))
 657                 die ("--patch is incompatible with all other options");
 658
 659         /* --track without -b should DWIM */
 660         if (0 < opts.track && !opts.new_branch) {
 661                 const char *argv0 = argv[0];
 662                 if (!argc || !strcmp(argv0, "--"))
 663                         die ("--track needs a branch name");
 664                 if (!prefixcmp(argv0, "refs/"))
 665                         argv0 += 5;
 666                 if (!prefixcmp(argv0, "remotes/"))
 667                         argv0 += 8;
 668                 argv0 = strchr(argv0, '/');
 669                 if (!argv0 || !argv0[1])
 670                         die ("Missing branch name; try -b");
 671                 opts.new_branch = argv0 + 1;
 672         }
 673
 674         if (conflict_style) {
 675                 opts.merge = 1; /* implied */
 676                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
 677         }
 678
 679         if (opts.force && opts.merge)
 680                 die("git checkout: -f and -m are incompatible");
 681
 682         /*
 683          * case 1: git checkout <ref> -- [<paths>]
 684          *
 685          *   <ref> must be a valid tree, everything after the '--' must be
 686          *   a path.
 687          *
 688          * case 2: git checkout -- [<paths>]
 689          *
 690          *   everything after the '--' must be paths.
 691          *
 692          * case 3: git checkout <something> [<paths>]
 693          *
 694          *   With no paths, if <something> is a commit, that is to
 695          *   switch to the branch or detach HEAD at it.
 696          *
 697          *   With no paths, if <something> is _not_ a commit, no -t nor -b
 698          *   was given, and there is a tracking branch whose name is
 699          *   <something> in one and only one remote, then this is a short-hand
 700          *   to fork local <something> from that remote tracking branch.
 701          *
 702          *   Otherwise <something> shall not be ambiguous.
 703          *   - If it's *only* a reference, treat it like case (1).
 704          *   - If it's only a path, treat it like case (2).
 705          *   - else: fail.
 706          *
 707          */
 708         if (argc) {
 709                 if (!strcmp(argv[0], "--")) {       /* case (2) */
 710                         argv++;
 711                         argc--;
 712                         goto no_reference;
 713                 }
 714
 715                 arg = argv[0];
 716                 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 717
 718                 if (!strcmp(arg, "-"))
 719                         arg = "@{-1}";
 720
 721                 if (get_sha1(arg, rev)) {
 722                         if (has_dash_dash)          /* case (1) */
 723                                 die("invalid reference: %s", arg);
 724                         if (!patch_mode &&
 725                             dwim_new_local_branch &&
 726                             opts.track == BRANCH_TRACK_UNSPECIFIED &&
 727                             !opts.new_branch &&
 728                             !check_filename(NULL, arg) &&
 729                             argc == 1) {
 730                                 const char *remote = unique_tracking_name(arg);
 731                                 if (!remote || get_sha1(remote, rev))
 732                                         goto no_reference;
 733                                 opts.new_branch = arg;
 734                                 arg = remote;
 735                                 /* DWIMmed to create local branch */
 736                         }
 737                         else
 738                                 goto no_reference;
 739                 }
 740
 741                 /* we can't end up being in (2) anymore, eat the argument */
 742                 argv++;
 743                 argc--;
 744
 745                 new.name = arg;
 746                 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
 747                         setup_branch_path(&new);
 748                         if (resolve_ref(new.path, rev, 1, NULL))
 749                                 new.commit = lookup_commit_reference(rev);
 750                         else
 751                                 new.path = NULL;
 752                         parse_commit(new.commit);
 753                         source_tree = new.commit->tree;
 754                 } else
 755                         source_tree = parse_tree_indirect(rev);
 756
 757                 if (!source_tree)                   /* case (1): want a tree */
 758                         die("reference is not a tree: %s", arg);
 759                 if (!has_dash_dash) {/* case (3 -> 1) */
 760                         /*
 761                          * Do not complain the most common case
 762                          *      git checkout branch
 763                          * even if there happen to be a file called 'branch';
 764                          * it would be extremely annoying.
 765                          */
 766                         if (argc)
 767                                 verify_non_filename(NULL, arg);
 768                 }
 769                 else {
 770                         argv++;
 771                         argc--;
 772                 }
 773         }
 774
 775 no_reference:
 776
 777         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
 778                 opts.track = git_branch_track;
 779
 780         if (argc) {
 781                 const char **pathspec = get_pathspec(prefix, argv);
 782
 783                 if (!pathspec)
 784                         die("invalid path specification");
 785
 786                 if (patch_mode)
 787                         return interactive_checkout(new.name, pathspec, &opts);
 788
 789                 /* Checkout paths */
 790                 if (opts.new_branch) {
 791                         if (argc == 1) {
 792                                 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]);
 793                         } else {
 794                                 die("git checkout: updating paths is incompatible with switching branches.");
 795                         }
 796                 }
 797
 798                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
 799                         die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
 800
 801                 return checkout_paths(source_tree, pathspec, &opts);
 802         }
 803
 804         if (patch_mode)
 805                 return interactive_checkout(new.name, NULL, &opts);
 806
 807         if (opts.new_branch) {
 808                 struct strbuf buf = STRBUF_INIT;
 809                 if (strbuf_check_branch_ref(&buf, opts.new_branch))
 810                         die("git checkout: we do not like '%s' as a branch name.",
 811                             opts.new_branch);
 812                 if (!get_sha1(buf.buf, rev))
 813                         die("git checkout: branch %s already exists", opts.new_branch);
 814                 strbuf_release(&buf);
 815         }
 816
 817         if (new.name && !new.commit) {
 818                 die("Cannot switch branch to a non-commit.");
 819         }
 820         if (opts.writeout_stage)
 821                 die("--ours/--theirs is incompatible with switching branches.");
 822
 823         return switch_branches(&opts, &new);
 824 }