21bac3a561dfa253d54f35f052c83e132396b598
   1#include "builtin.h"
   2#include "config.h"
   3#include "checkout.h"
   4#include "lockfile.h"
   5#include "parse-options.h"
   6#include "refs.h"
   7#include "object-store.h"
   8#include "commit.h"
   9#include "tree.h"
  10#include "tree-walk.h"
  11#include "cache-tree.h"
  12#include "unpack-trees.h"
  13#include "dir.h"
  14#include "run-command.h"
  15#include "merge-recursive.h"
  16#include "branch.h"
  17#include "diff.h"
  18#include "revision.h"
  19#include "remote.h"
  20#include "blob.h"
  21#include "xdiff-interface.h"
  22#include "ll-merge.h"
  23#include "resolve-undo.h"
  24#include "submodule-config.h"
  25#include "submodule.h"
  26
  27static int checkout_optimize_new_branch;
  28
  29static const char * const checkout_usage[] = {
  30        N_("git checkout [<options>] <branch>"),
  31        N_("git checkout [<options>] [<branch>] -- <file>..."),
  32        NULL,
  33};
  34
  35struct checkout_opts {
  36        int patch_mode;
  37        int quiet;
  38        int merge;
  39        int force;
  40        int force_detach;
  41        int writeout_stage;
  42        int overwrite_ignore;
  43        int ignore_skipworktree;
  44        int ignore_other_worktrees;
  45        int show_progress;
  46        /*
  47         * If new checkout options are added, skip_merge_working_tree
  48         * should be updated accordingly.
  49         */
  50
  51        const char *new_branch;
  52        const char *new_branch_force;
  53        const char *new_orphan_branch;
  54        int new_branch_log;
  55        enum branch_track track;
  56        struct diff_options diff_options;
  57
  58        int branch_exists;
  59        const char *prefix;
  60        struct pathspec pathspec;
  61        struct tree *source_tree;
  62};
  63
  64static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  65                              int changed)
  66{
  67        return run_hook_le(NULL, "post-checkout",
  68                           oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  69                           oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  70                           changed ? "1" : "0", NULL);
  71        /* "new_commit" can be NULL when checking out from the index before
  72           a commit exists. */
  73
  74}
  75
  76static int update_some(const struct object_id *oid, struct strbuf *base,
  77                const char *pathname, unsigned mode, int stage, void *context)
  78{
  79        int len;
  80        struct cache_entry *ce;
  81        int pos;
  82
  83        if (S_ISDIR(mode))
  84                return READ_TREE_RECURSIVE;
  85
  86        len = base->len + strlen(pathname);
  87        ce = xcalloc(1, cache_entry_size(len));
  88        oidcpy(&ce->oid, oid);
  89        memcpy(ce->name, base->buf, base->len);
  90        memcpy(ce->name + base->len, pathname, len - base->len);
  91        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  92        ce->ce_namelen = len;
  93        ce->ce_mode = create_ce_mode(mode);
  94
  95        /*
  96         * If the entry is the same as the current index, we can leave the old
  97         * entry in place. Whether it is UPTODATE or not, checkout_entry will
  98         * do the right thing.
  99         */
 100        pos = cache_name_pos(ce->name, ce->ce_namelen);
 101        if (pos >= 0) {
 102                struct cache_entry *old = active_cache[pos];
 103                if (ce->ce_mode == old->ce_mode &&
 104                    !oidcmp(&ce->oid, &old->oid)) {
 105                        old->ce_flags |= CE_UPDATE;
 106                        free(ce);
 107                        return 0;
 108                }
 109        }
 110
 111        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 112        return 0;
 113}
 114
 115static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 116{
 117        read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 118
 119        /* update the index with the given tree's info
 120         * for all args, expanding wildcards, and exit
 121         * with any non-zero return code.
 122         */
 123        return 0;
 124}
 125
 126static int skip_same_name(const struct cache_entry *ce, int pos)
 127{
 128        while (++pos < active_nr &&
 129               !strcmp(active_cache[pos]->name, ce->name))
 130                ; /* skip */
 131        return pos;
 132}
 133
 134static int check_stage(int stage, const struct cache_entry *ce, int pos)
 135{
 136        while (pos < active_nr &&
 137               !strcmp(active_cache[pos]->name, ce->name)) {
 138                if (ce_stage(active_cache[pos]) == stage)
 139                        return 0;
 140                pos++;
 141        }
 142        if (stage == 2)
 143                return error(_("path '%s' does not have our version"), ce->name);
 144        else
 145                return error(_("path '%s' does not have their version"), ce->name);
 146}
 147
 148static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 149{
 150        unsigned seen = 0;
 151        const char *name = ce->name;
 152
 153        while (pos < active_nr) {
 154                ce = active_cache[pos];
 155                if (strcmp(name, ce->name))
 156                        break;
 157                seen |= (1 << ce_stage(ce));
 158                pos++;
 159        }
 160        if ((stages & seen) != stages)
 161                return error(_("path '%s' does not have all necessary versions"),
 162                             name);
 163        return 0;
 164}
 165
 166static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 167                          const struct checkout *state)
 168{
 169        while (pos < active_nr &&
 170               !strcmp(active_cache[pos]->name, ce->name)) {
 171                if (ce_stage(active_cache[pos]) == stage)
 172                        return checkout_entry(active_cache[pos], state, NULL);
 173                pos++;
 174        }
 175        if (stage == 2)
 176                return error(_("path '%s' does not have our version"), ce->name);
 177        else
 178                return error(_("path '%s' does not have their version"), ce->name);
 179}
 180
 181static int checkout_merged(int pos, const struct checkout *state)
 182{
 183        struct cache_entry *ce = active_cache[pos];
 184        const char *path = ce->name;
 185        mmfile_t ancestor, ours, theirs;
 186        int status;
 187        struct object_id oid;
 188        mmbuffer_t result_buf;
 189        struct object_id threeway[3];
 190        unsigned mode = 0;
 191
 192        memset(threeway, 0, sizeof(threeway));
 193        while (pos < active_nr) {
 194                int stage;
 195                stage = ce_stage(ce);
 196                if (!stage || strcmp(path, ce->name))
 197                        break;
 198                oidcpy(&threeway[stage - 1], &ce->oid);
 199                if (stage == 2)
 200                        mode = create_ce_mode(ce->ce_mode);
 201                pos++;
 202                ce = active_cache[pos];
 203        }
 204        if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 205                return error(_("path '%s' does not have necessary versions"), path);
 206
 207        read_mmblob(&ancestor, &threeway[0]);
 208        read_mmblob(&ours, &threeway[1]);
 209        read_mmblob(&theirs, &threeway[2]);
 210
 211        /*
 212         * NEEDSWORK: re-create conflicts from merges with
 213         * merge.renormalize set, too
 214         */
 215        status = ll_merge(&result_buf, path, &ancestor, "base",
 216                          &ours, "ours", &theirs, "theirs", NULL);
 217        free(ancestor.ptr);
 218        free(ours.ptr);
 219        free(theirs.ptr);
 220        if (status < 0 || !result_buf.ptr) {
 221                free(result_buf.ptr);
 222                return error(_("path '%s': cannot merge"), path);
 223        }
 224
 225        /*
 226         * NEEDSWORK:
 227         * There is absolutely no reason to write this as a blob object
 228         * and create a phony cache entry.  This hack is primarily to get
 229         * to the write_entry() machinery that massages the contents to
 230         * work-tree format and writes out which only allows it for a
 231         * cache entry.  The code in write_entry() needs to be refactored
 232         * to allow us to feed a <buffer, size, mode> instead of a cache
 233         * entry.  Such a refactoring would help merge_recursive as well
 234         * (it also writes the merge result to the object database even
 235         * when it may contain conflicts).
 236         */
 237        if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 238                die(_("Unable to add merge result for '%s'"), path);
 239        free(result_buf.ptr);
 240        ce = make_cache_entry(mode, oid.hash, path, 2, 0);
 241        if (!ce)
 242                die(_("make_cache_entry failed for path '%s'"), path);
 243        status = checkout_entry(ce, state, NULL);
 244        free(ce);
 245        return status;
 246}
 247
 248static int checkout_paths(const struct checkout_opts *opts,
 249                          const char *revision)
 250{
 251        int pos;
 252        struct checkout state = CHECKOUT_INIT;
 253        static char *ps_matched;
 254        struct object_id rev;
 255        struct commit *head;
 256        int errs = 0;
 257        struct lock_file lock_file = LOCK_INIT;
 258
 259        if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 260                die(_("'%s' cannot be used with updating paths"), "--track");
 261
 262        if (opts->new_branch_log)
 263                die(_("'%s' cannot be used with updating paths"), "-l");
 264
 265        if (opts->force && opts->patch_mode)
 266                die(_("'%s' cannot be used with updating paths"), "-f");
 267
 268        if (opts->force_detach)
 269                die(_("'%s' cannot be used with updating paths"), "--detach");
 270
 271        if (opts->merge && opts->patch_mode)
 272                die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 273
 274        if (opts->force && opts->merge)
 275                die(_("'%s' cannot be used with %s"), "-f", "-m");
 276
 277        if (opts->new_branch)
 278                die(_("Cannot update paths and switch to branch '%s' at the same time."),
 279                    opts->new_branch);
 280
 281        if (opts->patch_mode)
 282                return run_add_interactive(revision, "--patch=checkout",
 283                                           &opts->pathspec);
 284
 285        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 286        if (read_cache_preload(&opts->pathspec) < 0)
 287                return error(_("index file corrupt"));
 288
 289        if (opts->source_tree)
 290                read_tree_some(opts->source_tree, &opts->pathspec);
 291
 292        ps_matched = xcalloc(opts->pathspec.nr, 1);
 293
 294        /*
 295         * Make sure all pathspecs participated in locating the paths
 296         * to be checked out.
 297         */
 298        for (pos = 0; pos < active_nr; pos++) {
 299                struct cache_entry *ce = active_cache[pos];
 300                ce->ce_flags &= ~CE_MATCHED;
 301                if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 302                        continue;
 303                if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 304                        /*
 305                         * "git checkout tree-ish -- path", but this entry
 306                         * is in the original index; it will not be checked
 307                         * out to the working tree and it does not matter
 308                         * if pathspec matched this entry.  We will not do
 309                         * anything to this entry at all.
 310                         */
 311                        continue;
 312                /*
 313                 * Either this entry came from the tree-ish we are
 314                 * checking the paths out of, or we are checking out
 315                 * of the index.
 316                 *
 317                 * If it comes from the tree-ish, we already know it
 318                 * matches the pathspec and could just stamp
 319                 * CE_MATCHED to it from update_some(). But we still
 320                 * need ps_matched and read_tree_recursive (and
 321                 * eventually tree_entry_interesting) cannot fill
 322                 * ps_matched yet. Once it can, we can avoid calling
 323                 * match_pathspec() for _all_ entries when
 324                 * opts->source_tree != NULL.
 325                 */
 326                if (ce_path_match(ce, &opts->pathspec, ps_matched))
 327                        ce->ce_flags |= CE_MATCHED;
 328        }
 329
 330        if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 331                free(ps_matched);
 332                return 1;
 333        }
 334        free(ps_matched);
 335
 336        /* "checkout -m path" to recreate conflicted state */
 337        if (opts->merge)
 338                unmerge_marked_index(&the_index);
 339
 340        /* Any unmerged paths? */
 341        for (pos = 0; pos < active_nr; pos++) {
 342                const struct cache_entry *ce = active_cache[pos];
 343                if (ce->ce_flags & CE_MATCHED) {
 344                        if (!ce_stage(ce))
 345                                continue;
 346                        if (opts->force) {
 347                                warning(_("path '%s' is unmerged"), ce->name);
 348                        } else if (opts->writeout_stage) {
 349                                errs |= check_stage(opts->writeout_stage, ce, pos);
 350                        } else if (opts->merge) {
 351                                errs |= check_stages((1<<2) | (1<<3), ce, pos);
 352                        } else {
 353                                errs = 1;
 354                                error(_("path '%s' is unmerged"), ce->name);
 355                        }
 356                        pos = skip_same_name(ce, pos) - 1;
 357                }
 358        }
 359        if (errs)
 360                return 1;
 361
 362        /* Now we are committed to check them out */
 363        state.force = 1;
 364        state.refresh_cache = 1;
 365        state.istate = &the_index;
 366
 367        enable_delayed_checkout(&state);
 368        for (pos = 0; pos < active_nr; pos++) {
 369                struct cache_entry *ce = active_cache[pos];
 370                if (ce->ce_flags & CE_MATCHED) {
 371                        if (!ce_stage(ce)) {
 372                                errs |= checkout_entry(ce, &state, NULL);
 373                                continue;
 374                        }
 375                        if (opts->writeout_stage)
 376                                errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 377                        else if (opts->merge)
 378                                errs |= checkout_merged(pos, &state);
 379                        pos = skip_same_name(ce, pos) - 1;
 380                }
 381        }
 382        errs |= finish_delayed_checkout(&state);
 383
 384        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 385                die(_("unable to write new index file"));
 386
 387        read_ref_full("HEAD", 0, &rev, NULL);
 388        head = lookup_commit_reference_gently(&rev, 1);
 389
 390        errs |= post_checkout_hook(head, head, 0);
 391        return errs;
 392}
 393
 394static void show_local_changes(struct object *head,
 395                               const struct diff_options *opts)
 396{
 397        struct rev_info rev;
 398        /* I think we want full paths, even if we're in a subdirectory. */
 399        init_revisions(&rev, NULL);
 400        rev.diffopt.flags = opts->flags;
 401        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 402        diff_setup_done(&rev.diffopt);
 403        add_pending_object(&rev, head, NULL);
 404        run_diff_index(&rev, 0);
 405}
 406
 407static void describe_detached_head(const char *msg, struct commit *commit)
 408{
 409        struct strbuf sb = STRBUF_INIT;
 410
 411        if (!parse_commit(commit))
 412                pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 413        if (print_sha1_ellipsis()) {
 414                fprintf(stderr, "%s %s... %s\n", msg,
 415                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 416        } else {
 417                fprintf(stderr, "%s %s %s\n", msg,
 418                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 419        }
 420        strbuf_release(&sb);
 421}
 422
 423static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 424                      int worktree, int *writeout_error)
 425{
 426        struct unpack_trees_options opts;
 427        struct tree_desc tree_desc;
 428
 429        memset(&opts, 0, sizeof(opts));
 430        opts.head_idx = -1;
 431        opts.update = worktree;
 432        opts.skip_unmerged = !worktree;
 433        opts.reset = 1;
 434        opts.merge = 1;
 435        opts.fn = oneway_merge;
 436        opts.verbose_update = o->show_progress;
 437        opts.src_index = &the_index;
 438        opts.dst_index = &the_index;
 439        parse_tree(tree);
 440        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 441        switch (unpack_trees(1, &tree_desc, &opts)) {
 442        case -2:
 443                *writeout_error = 1;
 444                /*
 445                 * We return 0 nevertheless, as the index is all right
 446                 * and more importantly we have made best efforts to
 447                 * update paths in the work tree, and we cannot revert
 448                 * them.
 449                 */
 450                /* fallthrough */
 451        case 0:
 452                return 0;
 453        default:
 454                return 128;
 455        }
 456}
 457
 458struct branch_info {
 459        const char *name; /* The short name used */
 460        const char *path; /* The full name of a real branch */
 461        struct commit *commit; /* The named commit */
 462        /*
 463         * if not null the branch is detached because it's already
 464         * checked out in this checkout
 465         */
 466        char *checkout;
 467};
 468
 469static void setup_branch_path(struct branch_info *branch)
 470{
 471        struct strbuf buf = STRBUF_INIT;
 472
 473        strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 474        if (strcmp(buf.buf, branch->name))
 475                branch->name = xstrdup(buf.buf);
 476        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 477        branch->path = strbuf_detach(&buf, NULL);
 478}
 479
 480/*
 481 * Skip merging the trees, updating the index and working directory if and
 482 * only if we are creating a new branch via "git checkout -b <new_branch>."
 483 */
 484static int skip_merge_working_tree(const struct checkout_opts *opts,
 485        const struct branch_info *old_branch_info,
 486        const struct branch_info *new_branch_info)
 487{
 488        /*
 489         * Do the merge if sparse checkout is on and the user has not opted in
 490         * to the optimized behavior
 491         */
 492        if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
 493                return 0;
 494
 495        /*
 496         * We must do the merge if we are actually moving to a new commit.
 497         */
 498        if (!old_branch_info->commit || !new_branch_info->commit ||
 499                oidcmp(&old_branch_info->commit->object.oid, &new_branch_info->commit->object.oid))
 500                return 0;
 501
 502        /*
 503         * opts->patch_mode cannot be used with switching branches so is
 504         * not tested here
 505         */
 506
 507        /*
 508         * opts->quiet only impacts output so doesn't require a merge
 509         */
 510
 511        /*
 512         * Honor the explicit request for a three-way merge or to throw away
 513         * local changes
 514         */
 515        if (opts->merge || opts->force)
 516                return 0;
 517
 518        /*
 519         * --detach is documented as "updating the index and the files in the
 520         * working tree" but this optimization skips those steps so fall through
 521         * to the regular code path.
 522         */
 523        if (opts->force_detach)
 524                return 0;
 525
 526        /*
 527         * opts->writeout_stage cannot be used with switching branches so is
 528         * not tested here
 529         */
 530
 531        /*
 532         * Honor the explicit ignore requests
 533         */
 534        if (!opts->overwrite_ignore || opts->ignore_skipworktree ||
 535                opts->ignore_other_worktrees)
 536                return 0;
 537
 538        /*
 539         * opts->show_progress only impacts output so doesn't require a merge
 540         */
 541
 542        /*
 543         * If we aren't creating a new branch any changes or updates will
 544         * happen in the existing branch.  Since that could only be updating
 545         * the index and working directory, we don't want to skip those steps
 546         * or we've defeated any purpose in running the command.
 547         */
 548        if (!opts->new_branch)
 549                return 0;
 550
 551        /*
 552         * new_branch_force is defined to "create/reset and checkout a branch"
 553         * so needs to go through the merge to do the reset
 554         */
 555        if (opts->new_branch_force)
 556                return 0;
 557
 558        /*
 559         * A new orphaned branch requrires the index and the working tree to be
 560         * adjusted to <start_point>
 561         */
 562        if (opts->new_orphan_branch)
 563                return 0;
 564
 565        /*
 566         * Remaining variables are not checkout options but used to track state
 567         */
 568
 569        return 1;
 570}
 571
 572static int merge_working_tree(const struct checkout_opts *opts,
 573                              struct branch_info *old_branch_info,
 574                              struct branch_info *new_branch_info,
 575                              int *writeout_error)
 576{
 577        int ret;
 578        struct lock_file lock_file = LOCK_INIT;
 579
 580        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 581        if (read_cache_preload(NULL) < 0)
 582                return error(_("index file corrupt"));
 583
 584        resolve_undo_clear();
 585        if (opts->force) {
 586                ret = reset_tree(get_commit_tree(new_branch_info->commit),
 587                                 opts, 1, writeout_error);
 588                if (ret)
 589                        return ret;
 590        } else {
 591                struct tree_desc trees[2];
 592                struct tree *tree;
 593                struct unpack_trees_options topts;
 594
 595                memset(&topts, 0, sizeof(topts));
 596                topts.head_idx = -1;
 597                topts.src_index = &the_index;
 598                topts.dst_index = &the_index;
 599
 600                setup_unpack_trees_porcelain(&topts, "checkout");
 601
 602                refresh_cache(REFRESH_QUIET);
 603
 604                if (unmerged_cache()) {
 605                        error(_("you need to resolve your current index first"));
 606                        return 1;
 607                }
 608
 609                /* 2-way merge to the new branch */
 610                topts.initial_checkout = is_cache_unborn();
 611                topts.update = 1;
 612                topts.merge = 1;
 613                topts.gently = opts->merge && old_branch_info->commit;
 614                topts.verbose_update = opts->show_progress;
 615                topts.fn = twoway_merge;
 616                if (opts->overwrite_ignore) {
 617                        topts.dir = xcalloc(1, sizeof(*topts.dir));
 618                        topts.dir->flags |= DIR_SHOW_IGNORED;
 619                        setup_standard_excludes(topts.dir);
 620                }
 621                tree = parse_tree_indirect(old_branch_info->commit ?
 622                                           &old_branch_info->commit->object.oid :
 623                                           the_hash_algo->empty_tree);
 624                init_tree_desc(&trees[0], tree->buffer, tree->size);
 625                tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
 626                init_tree_desc(&trees[1], tree->buffer, tree->size);
 627
 628                ret = unpack_trees(2, trees, &topts);
 629                clear_unpack_trees_porcelain(&topts);
 630                if (ret == -1) {
 631                        /*
 632                         * Unpack couldn't do a trivial merge; either
 633                         * give up or do a real merge, depending on
 634                         * whether the merge flag was used.
 635                         */
 636                        struct tree *result;
 637                        struct tree *work;
 638                        struct merge_options o;
 639                        if (!opts->merge)
 640                                return 1;
 641
 642                        /*
 643                         * Without old_branch_info->commit, the below is the same as
 644                         * the two-tree unpack we already tried and failed.
 645                         */
 646                        if (!old_branch_info->commit)
 647                                return 1;
 648
 649                        /* Do more real merge */
 650
 651                        /*
 652                         * We update the index fully, then write the
 653                         * tree from the index, then merge the new
 654                         * branch with the current tree, with the old
 655                         * branch as the base. Then we reset the index
 656                         * (but not the working tree) to the new
 657                         * branch, leaving the working tree as the
 658                         * merged version, but skipping unmerged
 659                         * entries in the index.
 660                         */
 661
 662                        add_files_to_cache(NULL, NULL, 0);
 663                        /*
 664                         * NEEDSWORK: carrying over local changes
 665                         * when branches have different end-of-line
 666                         * normalization (or clean+smudge rules) is
 667                         * a pain; plumb in an option to set
 668                         * o.renormalize?
 669                         */
 670                        init_merge_options(&o);
 671                        o.verbosity = 0;
 672                        work = write_tree_from_memory(&o);
 673
 674                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 675                                         opts, 1,
 676                                         writeout_error);
 677                        if (ret)
 678                                return ret;
 679                        o.ancestor = old_branch_info->name;
 680                        o.branch1 = new_branch_info->name;
 681                        o.branch2 = "local";
 682                        ret = merge_trees(&o,
 683                                          get_commit_tree(new_branch_info->commit),
 684                                          work,
 685                                          get_commit_tree(old_branch_info->commit),
 686                                          &result);
 687                        if (ret < 0)
 688                                exit(128);
 689                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 690                                         opts, 0,
 691                                         writeout_error);
 692                        strbuf_release(&o.obuf);
 693                        if (ret)
 694                                return ret;
 695                }
 696        }
 697
 698        if (!active_cache_tree)
 699                active_cache_tree = cache_tree();
 700
 701        if (!cache_tree_fully_valid(active_cache_tree))
 702                cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 703
 704        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 705                die(_("unable to write new index file"));
 706
 707        if (!opts->force && !opts->quiet)
 708                show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 709
 710        return 0;
 711}
 712
 713static void report_tracking(struct branch_info *new_branch_info)
 714{
 715        struct strbuf sb = STRBUF_INIT;
 716        struct branch *branch = branch_get(new_branch_info->name);
 717
 718        if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 719                return;
 720        fputs(sb.buf, stdout);
 721        strbuf_release(&sb);
 722}
 723
 724static void update_refs_for_switch(const struct checkout_opts *opts,
 725                                   struct branch_info *old_branch_info,
 726                                   struct branch_info *new_branch_info)
 727{
 728        struct strbuf msg = STRBUF_INIT;
 729        const char *old_desc, *reflog_msg;
 730        if (opts->new_branch) {
 731                if (opts->new_orphan_branch) {
 732                        char *refname;
 733
 734                        refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 735                        if (opts->new_branch_log &&
 736                            !should_autocreate_reflog(refname)) {
 737                                int ret;
 738                                struct strbuf err = STRBUF_INIT;
 739
 740                                ret = safe_create_reflog(refname, 1, &err);
 741                                if (ret) {
 742                                        fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 743                                                opts->new_orphan_branch, err.buf);
 744                                        strbuf_release(&err);
 745                                        free(refname);
 746                                        return;
 747                                }
 748                                strbuf_release(&err);
 749                        }
 750                        free(refname);
 751                }
 752                else
 753                        create_branch(opts->new_branch, new_branch_info->name,
 754                                      opts->new_branch_force ? 1 : 0,
 755                                      opts->new_branch_force ? 1 : 0,
 756                                      opts->new_branch_log,
 757                                      opts->quiet,
 758                                      opts->track);
 759                new_branch_info->name = opts->new_branch;
 760                setup_branch_path(new_branch_info);
 761        }
 762
 763        old_desc = old_branch_info->name;
 764        if (!old_desc && old_branch_info->commit)
 765                old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 766
 767        reflog_msg = getenv("GIT_REFLOG_ACTION");
 768        if (!reflog_msg)
 769                strbuf_addf(&msg, "checkout: moving from %s to %s",
 770                        old_desc ? old_desc : "(invalid)", new_branch_info->name);
 771        else
 772                strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 773
 774        if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 775                /* Nothing to do. */
 776        } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 777                update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 778                           REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 779                if (!opts->quiet) {
 780                        if (old_branch_info->path &&
 781                            advice_detached_head && !opts->force_detach)
 782                                detach_advice(new_branch_info->name);
 783                        describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 784                }
 785        } else if (new_branch_info->path) {     /* Switch branches. */
 786                if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 787                        die(_("unable to update HEAD"));
 788                if (!opts->quiet) {
 789                        if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 790                                if (opts->new_branch_force)
 791                                        fprintf(stderr, _("Reset branch '%s'\n"),
 792                                                new_branch_info->name);
 793                                else
 794                                        fprintf(stderr, _("Already on '%s'\n"),
 795                                                new_branch_info->name);
 796                        } else if (opts->new_branch) {
 797                                if (opts->branch_exists)
 798                                        fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 799                                else
 800                                        fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 801                        } else {
 802                                fprintf(stderr, _("Switched to branch '%s'\n"),
 803                                        new_branch_info->name);
 804                        }
 805                }
 806                if (old_branch_info->path && old_branch_info->name) {
 807                        if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 808                                delete_reflog(old_branch_info->path);
 809                }
 810        }
 811        remove_branch_state();
 812        strbuf_release(&msg);
 813        if (!opts->quiet &&
 814            (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 815                report_tracking(new_branch_info);
 816}
 817
 818static int add_pending_uninteresting_ref(const char *refname,
 819                                         const struct object_id *oid,
 820                                         int flags, void *cb_data)
 821{
 822        add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 823        return 0;
 824}
 825
 826static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 827{
 828        strbuf_addstr(sb, "  ");
 829        strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 830        strbuf_addch(sb, ' ');
 831        if (!parse_commit(commit))
 832                pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 833        strbuf_addch(sb, '\n');
 834}
 835
 836#define ORPHAN_CUTOFF 4
 837static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 838{
 839        struct commit *c, *last = NULL;
 840        struct strbuf sb = STRBUF_INIT;
 841        int lost = 0;
 842        while ((c = get_revision(revs)) != NULL) {
 843                if (lost < ORPHAN_CUTOFF)
 844                        describe_one_orphan(&sb, c);
 845                last = c;
 846                lost++;
 847        }
 848        if (ORPHAN_CUTOFF < lost) {
 849                int more = lost - ORPHAN_CUTOFF;
 850                if (more == 1)
 851                        describe_one_orphan(&sb, last);
 852                else
 853                        strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 854        }
 855
 856        fprintf(stderr,
 857                Q_(
 858                /* The singular version */
 859                "Warning: you are leaving %d commit behind, "
 860                "not connected to\n"
 861                "any of your branches:\n\n"
 862                "%s\n",
 863                /* The plural version */
 864                "Warning: you are leaving %d commits behind, "
 865                "not connected to\n"
 866                "any of your branches:\n\n"
 867                "%s\n",
 868                /* Give ngettext() the count */
 869                lost),
 870                lost,
 871                sb.buf);
 872        strbuf_release(&sb);
 873
 874        if (advice_detached_head)
 875                fprintf(stderr,
 876                        Q_(
 877                        /* The singular version */
 878                        "If you want to keep it by creating a new branch, "
 879                        "this may be a good time\nto do so with:\n\n"
 880                        " git branch <new-branch-name> %s\n\n",
 881                        /* The plural version */
 882                        "If you want to keep them by creating a new branch, "
 883                        "this may be a good time\nto do so with:\n\n"
 884                        " git branch <new-branch-name> %s\n\n",
 885                        /* Give ngettext() the count */
 886                        lost),
 887                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 888}
 889
 890/*
 891 * We are about to leave commit that was at the tip of a detached
 892 * HEAD.  If it is not reachable from any ref, this is the last chance
 893 * for the user to do so without resorting to reflog.
 894 */
 895static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 896{
 897        struct rev_info revs;
 898        struct object *object = &old_commit->object;
 899
 900        init_revisions(&revs, NULL);
 901        setup_revisions(0, NULL, &revs, NULL);
 902
 903        object->flags &= ~UNINTERESTING;
 904        add_pending_object(&revs, object, oid_to_hex(&object->oid));
 905
 906        for_each_ref(add_pending_uninteresting_ref, &revs);
 907        add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
 908
 909        if (prepare_revision_walk(&revs))
 910                die(_("internal error in revision walk"));
 911        if (!(old_commit->object.flags & UNINTERESTING))
 912                suggest_reattach(old_commit, &revs);
 913        else
 914                describe_detached_head(_("Previous HEAD position was"), old_commit);
 915
 916        /* Clean up objects used, as they will be reused. */
 917        clear_commit_marks_all(ALL_REV_FLAGS);
 918}
 919
 920static int switch_branches(const struct checkout_opts *opts,
 921                           struct branch_info *new_branch_info)
 922{
 923        int ret = 0;
 924        struct branch_info old_branch_info;
 925        void *path_to_free;
 926        struct object_id rev;
 927        int flag, writeout_error = 0;
 928        memset(&old_branch_info, 0, sizeof(old_branch_info));
 929        old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 930        if (old_branch_info.path)
 931                old_branch_info.commit = lookup_commit_reference_gently(&rev, 1);
 932        if (!(flag & REF_ISSYMREF))
 933                old_branch_info.path = NULL;
 934
 935        if (old_branch_info.path)
 936                skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
 937
 938        if (!new_branch_info->name) {
 939                new_branch_info->name = "HEAD";
 940                new_branch_info->commit = old_branch_info.commit;
 941                if (!new_branch_info->commit)
 942                        die(_("You are on a branch yet to be born"));
 943                parse_commit_or_die(new_branch_info->commit);
 944        }
 945
 946        /* optimize the "checkout -b <new_branch> path */
 947        if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
 948                if (!checkout_optimize_new_branch && !opts->quiet) {
 949                        if (read_cache_preload(NULL) < 0)
 950                                return error(_("index file corrupt"));
 951                        show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 952                }
 953        } else {
 954                ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 955                if (ret) {
 956                        free(path_to_free);
 957                        return ret;
 958                }
 959        }
 960
 961        if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
 962                orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
 963
 964        update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 965
 966        ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 967        free(path_to_free);
 968        return ret || writeout_error;
 969}
 970
 971static int git_checkout_config(const char *var, const char *value, void *cb)
 972{
 973        if (!strcmp(var, "checkout.optimizenewbranch")) {
 974                checkout_optimize_new_branch = git_config_bool(var, value);
 975                return 0;
 976        }
 977
 978        if (!strcmp(var, "diff.ignoresubmodules")) {
 979                struct checkout_opts *opts = cb;
 980                handle_ignore_submodules_arg(&opts->diff_options, value);
 981                return 0;
 982        }
 983
 984        if (starts_with(var, "submodule."))
 985                return git_default_submodule_config(var, value, NULL);
 986
 987        return git_xmerge_config(var, value, NULL);
 988}
 989
 990static int parse_branchname_arg(int argc, const char **argv,
 991                                int dwim_new_local_branch_ok,
 992                                struct branch_info *new_branch_info,
 993                                struct checkout_opts *opts,
 994                                struct object_id *rev)
 995{
 996        struct tree **source_tree = &opts->source_tree;
 997        const char **new_branch = &opts->new_branch;
 998        int argcount = 0;
 999        struct object_id branch_rev;
1000        const char *arg;
1001        int dash_dash_pos;
1002        int has_dash_dash = 0;
1003        int i;
1004
1005        /*
1006         * case 1: git checkout <ref> -- [<paths>]
1007         *
1008         *   <ref> must be a valid tree, everything after the '--' must be
1009         *   a path.
1010         *
1011         * case 2: git checkout -- [<paths>]
1012         *
1013         *   everything after the '--' must be paths.
1014         *
1015         * case 3: git checkout <something> [--]
1016         *
1017         *   (a) If <something> is a commit, that is to
1018         *       switch to the branch or detach HEAD at it.  As a special case,
1019         *       if <something> is A...B (missing A or B means HEAD but you can
1020         *       omit at most one side), and if there is a unique merge base
1021         *       between A and B, A...B names that merge base.
1022         *
1023         *   (b) If <something> is _not_ a commit, either "--" is present
1024         *       or <something> is not a path, no -t or -b was given, and
1025         *       and there is a tracking branch whose name is <something>
1026         *       in one and only one remote, then this is a short-hand to
1027         *       fork local <something> from that remote-tracking branch.
1028         *
1029         *   (c) Otherwise, if "--" is present, treat it like case (1).
1030         *
1031         *   (d) Otherwise :
1032         *       - if it's a reference, treat it like case (1)
1033         *       - else if it's a path, treat it like case (2)
1034         *       - else: fail.
1035         *
1036         * case 4: git checkout <something> <paths>
1037         *
1038         *   The first argument must not be ambiguous.
1039         *   - If it's *only* a reference, treat it like case (1).
1040         *   - If it's only a path, treat it like case (2).
1041         *   - else: fail.
1042         *
1043         */
1044        if (!argc)
1045                return 0;
1046
1047        arg = argv[0];
1048        dash_dash_pos = -1;
1049        for (i = 0; i < argc; i++) {
1050                if (!strcmp(argv[i], "--")) {
1051                        dash_dash_pos = i;
1052                        break;
1053                }
1054        }
1055        if (dash_dash_pos == 0)
1056                return 1; /* case (2) */
1057        else if (dash_dash_pos == 1)
1058                has_dash_dash = 1; /* case (3) or (1) */
1059        else if (dash_dash_pos >= 2)
1060                die(_("only one reference expected, %d given."), dash_dash_pos);
1061
1062        if (!strcmp(arg, "-"))
1063                arg = "@{-1}";
1064
1065        if (get_oid_mb(arg, rev)) {
1066                /*
1067                 * Either case (3) or (4), with <something> not being
1068                 * a commit, or an attempt to use case (1) with an
1069                 * invalid ref.
1070                 *
1071                 * It's likely an error, but we need to find out if
1072                 * we should auto-create the branch, case (3).(b).
1073                 */
1074                int recover_with_dwim = dwim_new_local_branch_ok;
1075
1076                if (!has_dash_dash &&
1077                    (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
1078                        recover_with_dwim = 0;
1079                /*
1080                 * Accept "git checkout foo" and "git checkout foo --"
1081                 * as candidates for dwim.
1082                 */
1083                if (!(argc == 1 && !has_dash_dash) &&
1084                    !(argc == 2 && has_dash_dash))
1085                        recover_with_dwim = 0;
1086
1087                if (recover_with_dwim) {
1088                        const char *remote = unique_tracking_name(arg, rev);
1089                        if (remote) {
1090                                *new_branch = arg;
1091                                arg = remote;
1092                                /* DWIMmed to create local branch, case (3).(b) */
1093                        } else {
1094                                recover_with_dwim = 0;
1095                        }
1096                }
1097
1098                if (!recover_with_dwim) {
1099                        if (has_dash_dash)
1100                                die(_("invalid reference: %s"), arg);
1101                        return argcount;
1102                }
1103        }
1104
1105        /* we can't end up being in (2) anymore, eat the argument */
1106        argcount++;
1107        argv++;
1108        argc--;
1109
1110        new_branch_info->name = arg;
1111        setup_branch_path(new_branch_info);
1112
1113        if (!check_refname_format(new_branch_info->path, 0) &&
1114            !read_ref(new_branch_info->path, &branch_rev))
1115                oidcpy(rev, &branch_rev);
1116        else
1117                new_branch_info->path = NULL; /* not an existing branch */
1118
1119        new_branch_info->commit = lookup_commit_reference_gently(rev, 1);
1120        if (!new_branch_info->commit) {
1121                /* not a commit */
1122                *source_tree = parse_tree_indirect(rev);
1123        } else {
1124                parse_commit_or_die(new_branch_info->commit);
1125                *source_tree = get_commit_tree(new_branch_info->commit);
1126        }
1127
1128        if (!*source_tree)                   /* case (1): want a tree */
1129                die(_("reference is not a tree: %s"), arg);
1130        if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1131                /*
1132                 * Do not complain the most common case
1133                 *      git checkout branch
1134                 * even if there happen to be a file called 'branch';
1135                 * it would be extremely annoying.
1136                 */
1137                if (argc)
1138                        verify_non_filename(opts->prefix, arg);
1139        } else {
1140                argcount++;
1141                argv++;
1142                argc--;
1143        }
1144
1145        return argcount;
1146}
1147
1148static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1149{
1150        int status;
1151        struct strbuf branch_ref = STRBUF_INIT;
1152
1153        if (!opts->new_branch)
1154                die(_("You are on a branch yet to be born"));
1155        strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1156        status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1157        strbuf_release(&branch_ref);
1158        if (!opts->quiet)
1159                fprintf(stderr, _("Switched to a new branch '%s'\n"),
1160                        opts->new_branch);
1161        return status;
1162}
1163
1164static int checkout_branch(struct checkout_opts *opts,
1165                           struct branch_info *new_branch_info)
1166{
1167        if (opts->pathspec.nr)
1168                die(_("paths cannot be used with switching branches"));
1169
1170        if (opts->patch_mode)
1171                die(_("'%s' cannot be used with switching branches"),
1172                    "--patch");
1173
1174        if (opts->writeout_stage)
1175                die(_("'%s' cannot be used with switching branches"),
1176                    "--ours/--theirs");
1177
1178        if (opts->force && opts->merge)
1179                die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1180
1181        if (opts->force_detach && opts->new_branch)
1182                die(_("'%s' cannot be used with '%s'"),
1183                    "--detach", "-b/-B/--orphan");
1184
1185        if (opts->new_orphan_branch) {
1186                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1187                        die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1188        } else if (opts->force_detach) {
1189                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1190                        die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1191        } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1192                opts->track = git_branch_track;
1193
1194        if (new_branch_info->name && !new_branch_info->commit)
1195                die(_("Cannot switch branch to a non-commit '%s'"),
1196                    new_branch_info->name);
1197
1198        if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1199            !opts->ignore_other_worktrees) {
1200                int flag;
1201                char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1202                if (head_ref &&
1203                    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1204                        die_if_checked_out(new_branch_info->path, 1);
1205                free(head_ref);
1206        }
1207
1208        if (!new_branch_info->commit && opts->new_branch) {
1209                struct object_id rev;
1210                int flag;
1211
1212                if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1213                    (flag & REF_ISSYMREF) && is_null_oid(&rev))
1214                        return switch_unborn_to_new_branch(opts);
1215        }
1216        return switch_branches(opts, new_branch_info);
1217}
1218
1219int cmd_checkout(int argc, const char **argv, const char *prefix)
1220{
1221        struct checkout_opts opts;
1222        struct branch_info new_branch_info;
1223        char *conflict_style = NULL;
1224        int dwim_new_local_branch = 1;
1225        struct option options[] = {
1226                OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1227                OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1228                           N_("create and checkout a new branch")),
1229                OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1230                           N_("create/reset and checkout a branch")),
1231                OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1232                OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1233                OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1234                        BRANCH_TRACK_EXPLICIT),
1235                OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1236                OPT_SET_INT_F('2', "ours", &opts.writeout_stage,
1237                              N_("checkout our version for unmerged files"),
1238                              2, PARSE_OPT_NONEG),
1239                OPT_SET_INT_F('3', "theirs", &opts.writeout_stage,
1240                              N_("checkout their version for unmerged files"),
1241                              3, PARSE_OPT_NONEG),
1242                OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)"),
1243                           PARSE_OPT_NOCOMPLETE),
1244                OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1245                OPT_BOOL_F(0, "overwrite-ignore", &opts.overwrite_ignore,
1246                           N_("update ignored files (default)"),
1247                           PARSE_OPT_NOCOMPLETE),
1248                OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1249                           N_("conflict style (merge or diff3)")),
1250                OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1251                OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1252                         N_("do not limit pathspecs to sparse entries only")),
1253                OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1254                                N_("second guess 'git checkout <no-such-branch>'")),
1255                OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1256                         N_("do not check if another worktree is holding the given ref")),
1257                { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1258                            "checkout", "control recursive updating of submodules",
1259                            PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1260                OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1261                OPT_END(),
1262        };
1263
1264        memset(&opts, 0, sizeof(opts));
1265        memset(&new_branch_info, 0, sizeof(new_branch_info));
1266        opts.overwrite_ignore = 1;
1267        opts.prefix = prefix;
1268        opts.show_progress = -1;
1269
1270        git_config(git_checkout_config, &opts);
1271
1272        opts.track = BRANCH_TRACK_UNSPECIFIED;
1273
1274        argc = parse_options(argc, argv, prefix, options, checkout_usage,
1275                             PARSE_OPT_KEEP_DASHDASH);
1276
1277        if (opts.show_progress < 0) {
1278                if (opts.quiet)
1279                        opts.show_progress = 0;
1280                else
1281                        opts.show_progress = isatty(2);
1282        }
1283
1284        if (conflict_style) {
1285                opts.merge = 1; /* implied */
1286                git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1287        }
1288
1289        if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1290                die(_("-b, -B and --orphan are mutually exclusive"));
1291
1292        /*
1293         * From here on, new_branch will contain the branch to be checked out,
1294         * and new_branch_force and new_orphan_branch will tell us which one of
1295         * -b/-B/--orphan is being used.
1296         */
1297        if (opts.new_branch_force)
1298                opts.new_branch = opts.new_branch_force;
1299
1300        if (opts.new_orphan_branch)
1301                opts.new_branch = opts.new_orphan_branch;
1302
1303        /* --track without -b/-B/--orphan should DWIM */
1304        if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1305                const char *argv0 = argv[0];
1306                if (!argc || !strcmp(argv0, "--"))
1307                        die (_("--track needs a branch name"));
1308                skip_prefix(argv0, "refs/", &argv0);
1309                skip_prefix(argv0, "remotes/", &argv0);
1310                argv0 = strchr(argv0, '/');
1311                if (!argv0 || !argv0[1])
1312                        die (_("Missing branch name; try -b"));
1313                opts.new_branch = argv0 + 1;
1314        }
1315
1316        /*
1317         * Extract branch name from command line arguments, so
1318         * all that is left is pathspecs.
1319         *
1320         * Handle
1321         *
1322         *  1) git checkout <tree> -- [<paths>]
1323         *  2) git checkout -- [<paths>]
1324         *  3) git checkout <something> [<paths>]
1325         *
1326         * including "last branch" syntax and DWIM-ery for names of
1327         * remote branches, erroring out for invalid or ambiguous cases.
1328         */
1329        if (argc) {
1330                struct object_id rev;
1331                int dwim_ok =
1332                        !opts.patch_mode &&
1333                        dwim_new_local_branch &&
1334                        opts.track == BRANCH_TRACK_UNSPECIFIED &&
1335                        !opts.new_branch;
1336                int n = parse_branchname_arg(argc, argv, dwim_ok,
1337                                             &new_branch_info, &opts, &rev);
1338                argv += n;
1339                argc -= n;
1340        }
1341
1342        if (argc) {
1343                parse_pathspec(&opts.pathspec, 0,
1344                               opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1345                               prefix, argv);
1346
1347                if (!opts.pathspec.nr)
1348                        die(_("invalid path specification"));
1349
1350                /*
1351                 * Try to give more helpful suggestion.
1352                 * new_branch && argc > 1 will be caught later.
1353                 */
1354                if (opts.new_branch && argc == 1)
1355                        die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1356                                argv[0], opts.new_branch);
1357
1358                if (opts.force_detach)
1359                        die(_("git checkout: --detach does not take a path argument '%s'"),
1360                            argv[0]);
1361
1362                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1363                        die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1364                              "checking out of the index."));
1365        }
1366
1367        if (opts.new_branch) {
1368                struct strbuf buf = STRBUF_INIT;
1369
1370                if (opts.new_branch_force)
1371                        opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1372                else
1373                        opts.branch_exists =
1374                                validate_new_branchname(opts.new_branch, &buf, 0);
1375                strbuf_release(&buf);
1376        }
1377
1378        UNLEAK(opts);
1379        if (opts.patch_mode || opts.pathspec.nr)
1380                return checkout_paths(&opts, new_branch_info.name);
1381        else
1382                return checkout_branch(&opts, &new_branch_info);
1383}