93fc2a58157d5cf89a257359491384c7b00c2255
   1#define USE_THE_INDEX_COMPATIBILITY_MACROS
   2#include "builtin.h"
   3#include "advice.h"
   4#include "blob.h"
   5#include "branch.h"
   6#include "cache-tree.h"
   7#include "checkout.h"
   8#include "commit.h"
   9#include "config.h"
  10#include "diff.h"
  11#include "dir.h"
  12#include "ll-merge.h"
  13#include "lockfile.h"
  14#include "merge-recursive.h"
  15#include "object-store.h"
  16#include "parse-options.h"
  17#include "refs.h"
  18#include "remote.h"
  19#include "resolve-undo.h"
  20#include "revision.h"
  21#include "run-command.h"
  22#include "submodule.h"
  23#include "submodule-config.h"
  24#include "tree.h"
  25#include "tree-walk.h"
  26#include "unpack-trees.h"
  27#include "xdiff-interface.h"
  28
  29static int checkout_optimize_new_branch;
  30
  31static const char * const checkout_usage[] = {
  32        N_("git checkout [<options>] <branch>"),
  33        N_("git checkout [<options>] [<branch>] -- <file>..."),
  34        NULL,
  35};
  36
  37struct checkout_opts {
  38        int patch_mode;
  39        int quiet;
  40        int merge;
  41        int force;
  42        int force_detach;
  43        int writeout_stage;
  44        int overwrite_ignore;
  45        int ignore_skipworktree;
  46        int ignore_other_worktrees;
  47        int show_progress;
  48        int count_checkout_paths;
  49        int overlay_mode;
  50        int no_dwim_new_local_branch;
  51
  52        /*
  53         * If new checkout options are added, skip_merge_working_tree
  54         * should be updated accordingly.
  55         */
  56
  57        const char *new_branch;
  58        const char *new_branch_force;
  59        const char *new_orphan_branch;
  60        int new_branch_log;
  61        enum branch_track track;
  62        struct diff_options diff_options;
  63        char *conflict_style;
  64
  65        int branch_exists;
  66        const char *prefix;
  67        struct pathspec pathspec;
  68        struct tree *source_tree;
  69};
  70
  71static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  72                              int changed)
  73{
  74        return run_hook_le(NULL, "post-checkout",
  75                           oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  76                           oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  77                           changed ? "1" : "0", NULL);
  78        /* "new_commit" can be NULL when checking out from the index before
  79           a commit exists. */
  80
  81}
  82
  83static int update_some(const struct object_id *oid, struct strbuf *base,
  84                const char *pathname, unsigned mode, int stage, void *context)
  85{
  86        int len;
  87        struct cache_entry *ce;
  88        int pos;
  89
  90        if (S_ISDIR(mode))
  91                return READ_TREE_RECURSIVE;
  92
  93        len = base->len + strlen(pathname);
  94        ce = make_empty_cache_entry(&the_index, len);
  95        oidcpy(&ce->oid, oid);
  96        memcpy(ce->name, base->buf, base->len);
  97        memcpy(ce->name + base->len, pathname, len - base->len);
  98        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  99        ce->ce_namelen = len;
 100        ce->ce_mode = create_ce_mode(mode);
 101
 102        /*
 103         * If the entry is the same as the current index, we can leave the old
 104         * entry in place. Whether it is UPTODATE or not, checkout_entry will
 105         * do the right thing.
 106         */
 107        pos = cache_name_pos(ce->name, ce->ce_namelen);
 108        if (pos >= 0) {
 109                struct cache_entry *old = active_cache[pos];
 110                if (ce->ce_mode == old->ce_mode &&
 111                    oideq(&ce->oid, &old->oid)) {
 112                        old->ce_flags |= CE_UPDATE;
 113                        discard_cache_entry(ce);
 114                        return 0;
 115                }
 116        }
 117
 118        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 119        return 0;
 120}
 121
 122static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 123{
 124        read_tree_recursive(the_repository, tree, "", 0, 0,
 125                            pathspec, update_some, NULL);
 126
 127        /* update the index with the given tree's info
 128         * for all args, expanding wildcards, and exit
 129         * with any non-zero return code.
 130         */
 131        return 0;
 132}
 133
 134static int skip_same_name(const struct cache_entry *ce, int pos)
 135{
 136        while (++pos < active_nr &&
 137               !strcmp(active_cache[pos]->name, ce->name))
 138                ; /* skip */
 139        return pos;
 140}
 141
 142static int check_stage(int stage, const struct cache_entry *ce, int pos,
 143                       int overlay_mode)
 144{
 145        while (pos < active_nr &&
 146               !strcmp(active_cache[pos]->name, ce->name)) {
 147                if (ce_stage(active_cache[pos]) == stage)
 148                        return 0;
 149                pos++;
 150        }
 151        if (!overlay_mode)
 152                return 0;
 153        if (stage == 2)
 154                return error(_("path '%s' does not have our version"), ce->name);
 155        else
 156                return error(_("path '%s' does not have their version"), ce->name);
 157}
 158
 159static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 160{
 161        unsigned seen = 0;
 162        const char *name = ce->name;
 163
 164        while (pos < active_nr) {
 165                ce = active_cache[pos];
 166                if (strcmp(name, ce->name))
 167                        break;
 168                seen |= (1 << ce_stage(ce));
 169                pos++;
 170        }
 171        if ((stages & seen) != stages)
 172                return error(_("path '%s' does not have all necessary versions"),
 173                             name);
 174        return 0;
 175}
 176
 177static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 178                          const struct checkout *state, int *nr_checkouts,
 179                          int overlay_mode)
 180{
 181        while (pos < active_nr &&
 182               !strcmp(active_cache[pos]->name, ce->name)) {
 183                if (ce_stage(active_cache[pos]) == stage)
 184                        return checkout_entry(active_cache[pos], state,
 185                                              NULL, nr_checkouts);
 186                pos++;
 187        }
 188        if (!overlay_mode) {
 189                unlink_entry(ce);
 190                return 0;
 191        }
 192        if (stage == 2)
 193                return error(_("path '%s' does not have our version"), ce->name);
 194        else
 195                return error(_("path '%s' does not have their version"), ce->name);
 196}
 197
 198static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
 199{
 200        struct cache_entry *ce = active_cache[pos];
 201        const char *path = ce->name;
 202        mmfile_t ancestor, ours, theirs;
 203        int status;
 204        struct object_id oid;
 205        mmbuffer_t result_buf;
 206        struct object_id threeway[3];
 207        unsigned mode = 0;
 208
 209        memset(threeway, 0, sizeof(threeway));
 210        while (pos < active_nr) {
 211                int stage;
 212                stage = ce_stage(ce);
 213                if (!stage || strcmp(path, ce->name))
 214                        break;
 215                oidcpy(&threeway[stage - 1], &ce->oid);
 216                if (stage == 2)
 217                        mode = create_ce_mode(ce->ce_mode);
 218                pos++;
 219                ce = active_cache[pos];
 220        }
 221        if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 222                return error(_("path '%s' does not have necessary versions"), path);
 223
 224        read_mmblob(&ancestor, &threeway[0]);
 225        read_mmblob(&ours, &threeway[1]);
 226        read_mmblob(&theirs, &threeway[2]);
 227
 228        /*
 229         * NEEDSWORK: re-create conflicts from merges with
 230         * merge.renormalize set, too
 231         */
 232        status = ll_merge(&result_buf, path, &ancestor, "base",
 233                          &ours, "ours", &theirs, "theirs",
 234                          state->istate, NULL);
 235        free(ancestor.ptr);
 236        free(ours.ptr);
 237        free(theirs.ptr);
 238        if (status < 0 || !result_buf.ptr) {
 239                free(result_buf.ptr);
 240                return error(_("path '%s': cannot merge"), path);
 241        }
 242
 243        /*
 244         * NEEDSWORK:
 245         * There is absolutely no reason to write this as a blob object
 246         * and create a phony cache entry.  This hack is primarily to get
 247         * to the write_entry() machinery that massages the contents to
 248         * work-tree format and writes out which only allows it for a
 249         * cache entry.  The code in write_entry() needs to be refactored
 250         * to allow us to feed a <buffer, size, mode> instead of a cache
 251         * entry.  Such a refactoring would help merge_recursive as well
 252         * (it also writes the merge result to the object database even
 253         * when it may contain conflicts).
 254         */
 255        if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 256                die(_("Unable to add merge result for '%s'"), path);
 257        free(result_buf.ptr);
 258        ce = make_transient_cache_entry(mode, &oid, path, 2);
 259        if (!ce)
 260                die(_("make_cache_entry failed for path '%s'"), path);
 261        status = checkout_entry(ce, state, NULL, nr_checkouts);
 262        discard_cache_entry(ce);
 263        return status;
 264}
 265
 266static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
 267                                         char *ps_matched,
 268                                         const struct checkout_opts *opts)
 269{
 270        ce->ce_flags &= ~CE_MATCHED;
 271        if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 272                return;
 273        if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 274                /*
 275                 * "git checkout tree-ish -- path", but this entry
 276                 * is in the original index but is not in tree-ish
 277                 * or does not match the pathspec; it will not be
 278                 * checked out to the working tree.  We will not do
 279                 * anything to this entry at all.
 280                 */
 281                return;
 282        /*
 283         * Either this entry came from the tree-ish we are
 284         * checking the paths out of, or we are checking out
 285         * of the index.
 286         *
 287         * If it comes from the tree-ish, we already know it
 288         * matches the pathspec and could just stamp
 289         * CE_MATCHED to it from update_some(). But we still
 290         * need ps_matched and read_tree_recursive (and
 291         * eventually tree_entry_interesting) cannot fill
 292         * ps_matched yet. Once it can, we can avoid calling
 293         * match_pathspec() for _all_ entries when
 294         * opts->source_tree != NULL.
 295         */
 296        if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 297                ce->ce_flags |= CE_MATCHED;
 298}
 299
 300static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
 301                                            char *ps_matched,
 302                                            const struct checkout_opts *opts)
 303{
 304        ce->ce_flags &= ~CE_MATCHED;
 305        if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 306                return;
 307        if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
 308                ce->ce_flags |= CE_MATCHED;
 309                if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 310                        /*
 311                         * In overlay mode, but the path is not in
 312                         * tree-ish, which means we should remove it
 313                         * from the index and the working tree.
 314                         */
 315                        ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
 316        }
 317}
 318
 319static int checkout_paths(const struct checkout_opts *opts,
 320                          const char *revision)
 321{
 322        int pos;
 323        struct checkout state = CHECKOUT_INIT;
 324        static char *ps_matched;
 325        struct object_id rev;
 326        struct commit *head;
 327        int errs = 0;
 328        struct lock_file lock_file = LOCK_INIT;
 329        int nr_checkouts = 0, nr_unmerged = 0;
 330
 331        trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
 332
 333        if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 334                die(_("'%s' cannot be used with updating paths"), "--track");
 335
 336        if (opts->new_branch_log)
 337                die(_("'%s' cannot be used with updating paths"), "-l");
 338
 339        if (opts->force && opts->patch_mode)
 340                die(_("'%s' cannot be used with updating paths"), "-f");
 341
 342        if (opts->force_detach)
 343                die(_("'%s' cannot be used with updating paths"), "--detach");
 344
 345        if (opts->merge && opts->patch_mode)
 346                die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 347
 348        if (opts->force && opts->merge)
 349                die(_("'%s' cannot be used with %s"), "-f", "-m");
 350
 351        if (opts->new_branch)
 352                die(_("Cannot update paths and switch to branch '%s' at the same time."),
 353                    opts->new_branch);
 354
 355        if (opts->patch_mode)
 356                return run_add_interactive(revision, "--patch=checkout",
 357                                           &opts->pathspec);
 358
 359        repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 360        if (read_cache_preload(&opts->pathspec) < 0)
 361                return error(_("index file corrupt"));
 362
 363        if (opts->source_tree)
 364                read_tree_some(opts->source_tree, &opts->pathspec);
 365
 366        ps_matched = xcalloc(opts->pathspec.nr, 1);
 367
 368        /*
 369         * Make sure all pathspecs participated in locating the paths
 370         * to be checked out.
 371         */
 372        for (pos = 0; pos < active_nr; pos++)
 373                if (opts->overlay_mode)
 374                        mark_ce_for_checkout_overlay(active_cache[pos],
 375                                                     ps_matched,
 376                                                     opts);
 377                else
 378                        mark_ce_for_checkout_no_overlay(active_cache[pos],
 379                                                        ps_matched,
 380                                                        opts);
 381
 382        if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 383                free(ps_matched);
 384                return 1;
 385        }
 386        free(ps_matched);
 387
 388        /* "checkout -m path" to recreate conflicted state */
 389        if (opts->merge)
 390                unmerge_marked_index(&the_index);
 391
 392        /* Any unmerged paths? */
 393        for (pos = 0; pos < active_nr; pos++) {
 394                const struct cache_entry *ce = active_cache[pos];
 395                if (ce->ce_flags & CE_MATCHED) {
 396                        if (!ce_stage(ce))
 397                                continue;
 398                        if (opts->force) {
 399                                warning(_("path '%s' is unmerged"), ce->name);
 400                        } else if (opts->writeout_stage) {
 401                                errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
 402                        } else if (opts->merge) {
 403                                errs |= check_stages((1<<2) | (1<<3), ce, pos);
 404                        } else {
 405                                errs = 1;
 406                                error(_("path '%s' is unmerged"), ce->name);
 407                        }
 408                        pos = skip_same_name(ce, pos) - 1;
 409                }
 410        }
 411        if (errs)
 412                return 1;
 413
 414        /* Now we are committed to check them out */
 415        state.force = 1;
 416        state.refresh_cache = 1;
 417        state.istate = &the_index;
 418
 419        enable_delayed_checkout(&state);
 420        for (pos = 0; pos < active_nr; pos++) {
 421                struct cache_entry *ce = active_cache[pos];
 422                if (ce->ce_flags & CE_MATCHED) {
 423                        if (!ce_stage(ce)) {
 424                                errs |= checkout_entry(ce, &state,
 425                                                       NULL, &nr_checkouts);
 426                                continue;
 427                        }
 428                        if (opts->writeout_stage)
 429                                errs |= checkout_stage(opts->writeout_stage,
 430                                                       ce, pos,
 431                                                       &state,
 432                                                       &nr_checkouts, opts->overlay_mode);
 433                        else if (opts->merge)
 434                                errs |= checkout_merged(pos, &state,
 435                                                        &nr_unmerged);
 436                        pos = skip_same_name(ce, pos) - 1;
 437                }
 438        }
 439        remove_marked_cache_entries(&the_index, 1);
 440        remove_scheduled_dirs();
 441        errs |= finish_delayed_checkout(&state, &nr_checkouts);
 442
 443        if (opts->count_checkout_paths) {
 444                if (nr_unmerged)
 445                        fprintf_ln(stderr, Q_("Recreated %d merge conflict",
 446                                              "Recreated %d merge conflicts",
 447                                              nr_unmerged),
 448                                   nr_unmerged);
 449                if (opts->source_tree)
 450                        fprintf_ln(stderr, Q_("Updated %d path from %s",
 451                                              "Updated %d paths from %s",
 452                                              nr_checkouts),
 453                                   nr_checkouts,
 454                                   find_unique_abbrev(&opts->source_tree->object.oid,
 455                                                      DEFAULT_ABBREV));
 456                else if (!nr_unmerged || nr_checkouts)
 457                        fprintf_ln(stderr, Q_("Updated %d path from the index",
 458                                              "Updated %d paths from the index",
 459                                              nr_checkouts),
 460                                   nr_checkouts);
 461        }
 462
 463        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 464                die(_("unable to write new index file"));
 465
 466        read_ref_full("HEAD", 0, &rev, NULL);
 467        head = lookup_commit_reference_gently(the_repository, &rev, 1);
 468
 469        errs |= post_checkout_hook(head, head, 0);
 470        return errs;
 471}
 472
 473static void show_local_changes(struct object *head,
 474                               const struct diff_options *opts)
 475{
 476        struct rev_info rev;
 477        /* I think we want full paths, even if we're in a subdirectory. */
 478        repo_init_revisions(the_repository, &rev, NULL);
 479        rev.diffopt.flags = opts->flags;
 480        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 481        diff_setup_done(&rev.diffopt);
 482        add_pending_object(&rev, head, NULL);
 483        run_diff_index(&rev, 0);
 484}
 485
 486static void describe_detached_head(const char *msg, struct commit *commit)
 487{
 488        struct strbuf sb = STRBUF_INIT;
 489
 490        if (!parse_commit(commit))
 491                pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 492        if (print_sha1_ellipsis()) {
 493                fprintf(stderr, "%s %s... %s\n", msg,
 494                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 495        } else {
 496                fprintf(stderr, "%s %s %s\n", msg,
 497                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 498        }
 499        strbuf_release(&sb);
 500}
 501
 502static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 503                      int worktree, int *writeout_error)
 504{
 505        struct unpack_trees_options opts;
 506        struct tree_desc tree_desc;
 507
 508        memset(&opts, 0, sizeof(opts));
 509        opts.head_idx = -1;
 510        opts.update = worktree;
 511        opts.skip_unmerged = !worktree;
 512        opts.reset = 1;
 513        opts.merge = 1;
 514        opts.fn = oneway_merge;
 515        opts.verbose_update = o->show_progress;
 516        opts.src_index = &the_index;
 517        opts.dst_index = &the_index;
 518        parse_tree(tree);
 519        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 520        switch (unpack_trees(1, &tree_desc, &opts)) {
 521        case -2:
 522                *writeout_error = 1;
 523                /*
 524                 * We return 0 nevertheless, as the index is all right
 525                 * and more importantly we have made best efforts to
 526                 * update paths in the work tree, and we cannot revert
 527                 * them.
 528                 */
 529                /* fallthrough */
 530        case 0:
 531                return 0;
 532        default:
 533                return 128;
 534        }
 535}
 536
 537struct branch_info {
 538        const char *name; /* The short name used */
 539        const char *path; /* The full name of a real branch */
 540        struct commit *commit; /* The named commit */
 541        /*
 542         * if not null the branch is detached because it's already
 543         * checked out in this checkout
 544         */
 545        char *checkout;
 546};
 547
 548static void setup_branch_path(struct branch_info *branch)
 549{
 550        struct strbuf buf = STRBUF_INIT;
 551
 552        strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 553        if (strcmp(buf.buf, branch->name))
 554                branch->name = xstrdup(buf.buf);
 555        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 556        branch->path = strbuf_detach(&buf, NULL);
 557}
 558
 559/*
 560 * Skip merging the trees, updating the index and working directory if and
 561 * only if we are creating a new branch via "git checkout -b <new_branch>."
 562 */
 563static int skip_merge_working_tree(const struct checkout_opts *opts,
 564        const struct branch_info *old_branch_info,
 565        const struct branch_info *new_branch_info)
 566{
 567        /*
 568         * Do the merge if sparse checkout is on and the user has not opted in
 569         * to the optimized behavior
 570         */
 571        if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
 572                return 0;
 573
 574        /*
 575         * We must do the merge if we are actually moving to a new commit.
 576         */
 577        if (!old_branch_info->commit || !new_branch_info->commit ||
 578                !oideq(&old_branch_info->commit->object.oid,
 579                       &new_branch_info->commit->object.oid))
 580                return 0;
 581
 582        /*
 583         * opts->patch_mode cannot be used with switching branches so is
 584         * not tested here
 585         */
 586
 587        /*
 588         * opts->quiet only impacts output so doesn't require a merge
 589         */
 590
 591        /*
 592         * Honor the explicit request for a three-way merge or to throw away
 593         * local changes
 594         */
 595        if (opts->merge || opts->force)
 596                return 0;
 597
 598        /*
 599         * --detach is documented as "updating the index and the files in the
 600         * working tree" but this optimization skips those steps so fall through
 601         * to the regular code path.
 602         */
 603        if (opts->force_detach)
 604                return 0;
 605
 606        /*
 607         * opts->writeout_stage cannot be used with switching branches so is
 608         * not tested here
 609         */
 610
 611        /*
 612         * Honor the explicit ignore requests
 613         */
 614        if (!opts->overwrite_ignore || opts->ignore_skipworktree ||
 615                opts->ignore_other_worktrees)
 616                return 0;
 617
 618        /*
 619         * opts->show_progress only impacts output so doesn't require a merge
 620         */
 621
 622        /*
 623         * opts->overlay_mode cannot be used with switching branches so is
 624         * not tested here
 625         */
 626
 627        /*
 628         * If we aren't creating a new branch any changes or updates will
 629         * happen in the existing branch.  Since that could only be updating
 630         * the index and working directory, we don't want to skip those steps
 631         * or we've defeated any purpose in running the command.
 632         */
 633        if (!opts->new_branch)
 634                return 0;
 635
 636        /*
 637         * new_branch_force is defined to "create/reset and checkout a branch"
 638         * so needs to go through the merge to do the reset
 639         */
 640        if (opts->new_branch_force)
 641                return 0;
 642
 643        /*
 644         * A new orphaned branch requrires the index and the working tree to be
 645         * adjusted to <start_point>
 646         */
 647        if (opts->new_orphan_branch)
 648                return 0;
 649
 650        /*
 651         * Remaining variables are not checkout options but used to track state
 652         */
 653
 654         /*
 655          * Do the merge if this is the initial checkout. We cannot use
 656          * is_cache_unborn() here because the index hasn't been loaded yet
 657          * so cache_nr and timestamp.sec are always zero.
 658          */
 659        if (!file_exists(get_index_file()))
 660                return 0;
 661
 662        return 1;
 663}
 664
 665static int merge_working_tree(const struct checkout_opts *opts,
 666                              struct branch_info *old_branch_info,
 667                              struct branch_info *new_branch_info,
 668                              int *writeout_error)
 669{
 670        int ret;
 671        struct lock_file lock_file = LOCK_INIT;
 672
 673        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 674        if (read_cache_preload(NULL) < 0)
 675                return error(_("index file corrupt"));
 676
 677        resolve_undo_clear();
 678        if (opts->force) {
 679                ret = reset_tree(get_commit_tree(new_branch_info->commit),
 680                                 opts, 1, writeout_error);
 681                if (ret)
 682                        return ret;
 683        } else {
 684                struct tree_desc trees[2];
 685                struct tree *tree;
 686                struct unpack_trees_options topts;
 687
 688                memset(&topts, 0, sizeof(topts));
 689                topts.head_idx = -1;
 690                topts.src_index = &the_index;
 691                topts.dst_index = &the_index;
 692
 693                setup_unpack_trees_porcelain(&topts, "checkout");
 694
 695                refresh_cache(REFRESH_QUIET);
 696
 697                if (unmerged_cache()) {
 698                        error(_("you need to resolve your current index first"));
 699                        return 1;
 700                }
 701
 702                /* 2-way merge to the new branch */
 703                topts.initial_checkout = is_cache_unborn();
 704                topts.update = 1;
 705                topts.merge = 1;
 706                topts.gently = opts->merge && old_branch_info->commit;
 707                topts.verbose_update = opts->show_progress;
 708                topts.fn = twoway_merge;
 709                if (opts->overwrite_ignore) {
 710                        topts.dir = xcalloc(1, sizeof(*topts.dir));
 711                        topts.dir->flags |= DIR_SHOW_IGNORED;
 712                        setup_standard_excludes(topts.dir);
 713                }
 714                tree = parse_tree_indirect(old_branch_info->commit ?
 715                                           &old_branch_info->commit->object.oid :
 716                                           the_hash_algo->empty_tree);
 717                init_tree_desc(&trees[0], tree->buffer, tree->size);
 718                tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
 719                init_tree_desc(&trees[1], tree->buffer, tree->size);
 720
 721                ret = unpack_trees(2, trees, &topts);
 722                clear_unpack_trees_porcelain(&topts);
 723                if (ret == -1) {
 724                        /*
 725                         * Unpack couldn't do a trivial merge; either
 726                         * give up or do a real merge, depending on
 727                         * whether the merge flag was used.
 728                         */
 729                        struct tree *result;
 730                        struct tree *work;
 731                        struct merge_options o;
 732                        if (!opts->merge)
 733                                return 1;
 734
 735                        /*
 736                         * Without old_branch_info->commit, the below is the same as
 737                         * the two-tree unpack we already tried and failed.
 738                         */
 739                        if (!old_branch_info->commit)
 740                                return 1;
 741
 742                        /* Do more real merge */
 743
 744                        /*
 745                         * We update the index fully, then write the
 746                         * tree from the index, then merge the new
 747                         * branch with the current tree, with the old
 748                         * branch as the base. Then we reset the index
 749                         * (but not the working tree) to the new
 750                         * branch, leaving the working tree as the
 751                         * merged version, but skipping unmerged
 752                         * entries in the index.
 753                         */
 754
 755                        add_files_to_cache(NULL, NULL, 0);
 756                        /*
 757                         * NEEDSWORK: carrying over local changes
 758                         * when branches have different end-of-line
 759                         * normalization (or clean+smudge rules) is
 760                         * a pain; plumb in an option to set
 761                         * o.renormalize?
 762                         */
 763                        init_merge_options(&o, the_repository);
 764                        o.verbosity = 0;
 765                        work = write_tree_from_memory(&o);
 766
 767                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 768                                         opts, 1,
 769                                         writeout_error);
 770                        if (ret)
 771                                return ret;
 772                        o.ancestor = old_branch_info->name;
 773                        o.branch1 = new_branch_info->name;
 774                        o.branch2 = "local";
 775                        ret = merge_trees(&o,
 776                                          get_commit_tree(new_branch_info->commit),
 777                                          work,
 778                                          get_commit_tree(old_branch_info->commit),
 779                                          &result);
 780                        if (ret < 0)
 781                                exit(128);
 782                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 783                                         opts, 0,
 784                                         writeout_error);
 785                        strbuf_release(&o.obuf);
 786                        if (ret)
 787                                return ret;
 788                }
 789        }
 790
 791        if (!active_cache_tree)
 792                active_cache_tree = cache_tree();
 793
 794        if (!cache_tree_fully_valid(active_cache_tree))
 795                cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 796
 797        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 798                die(_("unable to write new index file"));
 799
 800        if (!opts->force && !opts->quiet)
 801                show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 802
 803        return 0;
 804}
 805
 806static void report_tracking(struct branch_info *new_branch_info)
 807{
 808        struct strbuf sb = STRBUF_INIT;
 809        struct branch *branch = branch_get(new_branch_info->name);
 810
 811        if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 812                return;
 813        fputs(sb.buf, stdout);
 814        strbuf_release(&sb);
 815}
 816
 817static void update_refs_for_switch(const struct checkout_opts *opts,
 818                                   struct branch_info *old_branch_info,
 819                                   struct branch_info *new_branch_info)
 820{
 821        struct strbuf msg = STRBUF_INIT;
 822        const char *old_desc, *reflog_msg;
 823        if (opts->new_branch) {
 824                if (opts->new_orphan_branch) {
 825                        char *refname;
 826
 827                        refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 828                        if (opts->new_branch_log &&
 829                            !should_autocreate_reflog(refname)) {
 830                                int ret;
 831                                struct strbuf err = STRBUF_INIT;
 832
 833                                ret = safe_create_reflog(refname, 1, &err);
 834                                if (ret) {
 835                                        fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 836                                                opts->new_orphan_branch, err.buf);
 837                                        strbuf_release(&err);
 838                                        free(refname);
 839                                        return;
 840                                }
 841                                strbuf_release(&err);
 842                        }
 843                        free(refname);
 844                }
 845                else
 846                        create_branch(the_repository,
 847                                      opts->new_branch, new_branch_info->name,
 848                                      opts->new_branch_force ? 1 : 0,
 849                                      opts->new_branch_force ? 1 : 0,
 850                                      opts->new_branch_log,
 851                                      opts->quiet,
 852                                      opts->track);
 853                new_branch_info->name = opts->new_branch;
 854                setup_branch_path(new_branch_info);
 855        }
 856
 857        old_desc = old_branch_info->name;
 858        if (!old_desc && old_branch_info->commit)
 859                old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 860
 861        reflog_msg = getenv("GIT_REFLOG_ACTION");
 862        if (!reflog_msg)
 863                strbuf_addf(&msg, "checkout: moving from %s to %s",
 864                        old_desc ? old_desc : "(invalid)", new_branch_info->name);
 865        else
 866                strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 867
 868        if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 869                /* Nothing to do. */
 870        } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 871                update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 872                           REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 873                if (!opts->quiet) {
 874                        if (old_branch_info->path &&
 875                            advice_detached_head && !opts->force_detach)
 876                                detach_advice(new_branch_info->name);
 877                        describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 878                }
 879        } else if (new_branch_info->path) {     /* Switch branches. */
 880                if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 881                        die(_("unable to update HEAD"));
 882                if (!opts->quiet) {
 883                        if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 884                                if (opts->new_branch_force)
 885                                        fprintf(stderr, _("Reset branch '%s'\n"),
 886                                                new_branch_info->name);
 887                                else
 888                                        fprintf(stderr, _("Already on '%s'\n"),
 889                                                new_branch_info->name);
 890                        } else if (opts->new_branch) {
 891                                if (opts->branch_exists)
 892                                        fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 893                                else
 894                                        fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 895                        } else {
 896                                fprintf(stderr, _("Switched to branch '%s'\n"),
 897                                        new_branch_info->name);
 898                        }
 899                }
 900                if (old_branch_info->path && old_branch_info->name) {
 901                        if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 902                                delete_reflog(old_branch_info->path);
 903                }
 904        }
 905        remove_branch_state(the_repository, !opts->quiet);
 906        strbuf_release(&msg);
 907        if (!opts->quiet &&
 908            (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 909                report_tracking(new_branch_info);
 910}
 911
 912static int add_pending_uninteresting_ref(const char *refname,
 913                                         const struct object_id *oid,
 914                                         int flags, void *cb_data)
 915{
 916        add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 917        return 0;
 918}
 919
 920static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 921{
 922        strbuf_addstr(sb, "  ");
 923        strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 924        strbuf_addch(sb, ' ');
 925        if (!parse_commit(commit))
 926                pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 927        strbuf_addch(sb, '\n');
 928}
 929
 930#define ORPHAN_CUTOFF 4
 931static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 932{
 933        struct commit *c, *last = NULL;
 934        struct strbuf sb = STRBUF_INIT;
 935        int lost = 0;
 936        while ((c = get_revision(revs)) != NULL) {
 937                if (lost < ORPHAN_CUTOFF)
 938                        describe_one_orphan(&sb, c);
 939                last = c;
 940                lost++;
 941        }
 942        if (ORPHAN_CUTOFF < lost) {
 943                int more = lost - ORPHAN_CUTOFF;
 944                if (more == 1)
 945                        describe_one_orphan(&sb, last);
 946                else
 947                        strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 948        }
 949
 950        fprintf(stderr,
 951                Q_(
 952                /* The singular version */
 953                "Warning: you are leaving %d commit behind, "
 954                "not connected to\n"
 955                "any of your branches:\n\n"
 956                "%s\n",
 957                /* The plural version */
 958                "Warning: you are leaving %d commits behind, "
 959                "not connected to\n"
 960                "any of your branches:\n\n"
 961                "%s\n",
 962                /* Give ngettext() the count */
 963                lost),
 964                lost,
 965                sb.buf);
 966        strbuf_release(&sb);
 967
 968        if (advice_detached_head)
 969                fprintf(stderr,
 970                        Q_(
 971                        /* The singular version */
 972                        "If you want to keep it by creating a new branch, "
 973                        "this may be a good time\nto do so with:\n\n"
 974                        " git branch <new-branch-name> %s\n\n",
 975                        /* The plural version */
 976                        "If you want to keep them by creating a new branch, "
 977                        "this may be a good time\nto do so with:\n\n"
 978                        " git branch <new-branch-name> %s\n\n",
 979                        /* Give ngettext() the count */
 980                        lost),
 981                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 982}
 983
 984/*
 985 * We are about to leave commit that was at the tip of a detached
 986 * HEAD.  If it is not reachable from any ref, this is the last chance
 987 * for the user to do so without resorting to reflog.
 988 */
 989static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 990{
 991        struct rev_info revs;
 992        struct object *object = &old_commit->object;
 993
 994        repo_init_revisions(the_repository, &revs, NULL);
 995        setup_revisions(0, NULL, &revs, NULL);
 996
 997        object->flags &= ~UNINTERESTING;
 998        add_pending_object(&revs, object, oid_to_hex(&object->oid));
 999
1000        for_each_ref(add_pending_uninteresting_ref, &revs);
1001        add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
1002
1003        if (prepare_revision_walk(&revs))
1004                die(_("internal error in revision walk"));
1005        if (!(old_commit->object.flags & UNINTERESTING))
1006                suggest_reattach(old_commit, &revs);
1007        else
1008                describe_detached_head(_("Previous HEAD position was"), old_commit);
1009
1010        /* Clean up objects used, as they will be reused. */
1011        clear_commit_marks_all(ALL_REV_FLAGS);
1012}
1013
1014static int switch_branches(const struct checkout_opts *opts,
1015                           struct branch_info *new_branch_info)
1016{
1017        int ret = 0;
1018        struct branch_info old_branch_info;
1019        void *path_to_free;
1020        struct object_id rev;
1021        int flag, writeout_error = 0;
1022
1023        trace2_cmd_mode("branch");
1024
1025        memset(&old_branch_info, 0, sizeof(old_branch_info));
1026        old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1027        if (old_branch_info.path)
1028                old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1029        if (!(flag & REF_ISSYMREF))
1030                old_branch_info.path = NULL;
1031
1032        if (old_branch_info.path)
1033                skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1034
1035        if (!new_branch_info->name) {
1036                new_branch_info->name = "HEAD";
1037                new_branch_info->commit = old_branch_info.commit;
1038                if (!new_branch_info->commit)
1039                        die(_("You are on a branch yet to be born"));
1040                parse_commit_or_die(new_branch_info->commit);
1041        }
1042
1043        /* optimize the "checkout -b <new_branch> path */
1044        if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
1045                if (!checkout_optimize_new_branch && !opts->quiet) {
1046                        if (read_cache_preload(NULL) < 0)
1047                                return error(_("index file corrupt"));
1048                        show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
1049                }
1050        } else {
1051                ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1052                if (ret) {
1053                        free(path_to_free);
1054                        return ret;
1055                }
1056        }
1057
1058        if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1059                orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1060
1061        update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1062
1063        ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1064        free(path_to_free);
1065        return ret || writeout_error;
1066}
1067
1068static int git_checkout_config(const char *var, const char *value, void *cb)
1069{
1070        if (!strcmp(var, "checkout.optimizenewbranch")) {
1071                checkout_optimize_new_branch = git_config_bool(var, value);
1072                return 0;
1073        }
1074
1075        if (!strcmp(var, "diff.ignoresubmodules")) {
1076                struct checkout_opts *opts = cb;
1077                handle_ignore_submodules_arg(&opts->diff_options, value);
1078                return 0;
1079        }
1080
1081        if (starts_with(var, "submodule."))
1082                return git_default_submodule_config(var, value, NULL);
1083
1084        return git_xmerge_config(var, value, NULL);
1085}
1086
1087static void setup_new_branch_info_and_source_tree(
1088        struct branch_info *new_branch_info,
1089        struct checkout_opts *opts,
1090        struct object_id *rev,
1091        const char *arg)
1092{
1093        struct tree **source_tree = &opts->source_tree;
1094        struct object_id branch_rev;
1095
1096        new_branch_info->name = arg;
1097        setup_branch_path(new_branch_info);
1098
1099        if (!check_refname_format(new_branch_info->path, 0) &&
1100            !read_ref(new_branch_info->path, &branch_rev))
1101                oidcpy(rev, &branch_rev);
1102        else
1103                new_branch_info->path = NULL; /* not an existing branch */
1104
1105        new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1106        if (!new_branch_info->commit) {
1107                /* not a commit */
1108                *source_tree = parse_tree_indirect(rev);
1109        } else {
1110                parse_commit_or_die(new_branch_info->commit);
1111                *source_tree = get_commit_tree(new_branch_info->commit);
1112        }
1113}
1114
1115static int parse_branchname_arg(int argc, const char **argv,
1116                                int dwim_new_local_branch_ok,
1117                                struct branch_info *new_branch_info,
1118                                struct checkout_opts *opts,
1119                                struct object_id *rev,
1120                                int *dwim_remotes_matched)
1121{
1122        const char **new_branch = &opts->new_branch;
1123        int argcount = 0;
1124        const char *arg;
1125        int dash_dash_pos;
1126        int has_dash_dash = 0;
1127        int i;
1128
1129        /*
1130         * case 1: git checkout <ref> -- [<paths>]
1131         *
1132         *   <ref> must be a valid tree, everything after the '--' must be
1133         *   a path.
1134         *
1135         * case 2: git checkout -- [<paths>]
1136         *
1137         *   everything after the '--' must be paths.
1138         *
1139         * case 3: git checkout <something> [--]
1140         *
1141         *   (a) If <something> is a commit, that is to
1142         *       switch to the branch or detach HEAD at it.  As a special case,
1143         *       if <something> is A...B (missing A or B means HEAD but you can
1144         *       omit at most one side), and if there is a unique merge base
1145         *       between A and B, A...B names that merge base.
1146         *
1147         *   (b) If <something> is _not_ a commit, either "--" is present
1148         *       or <something> is not a path, no -t or -b was given, and
1149         *       and there is a tracking branch whose name is <something>
1150         *       in one and only one remote (or if the branch exists on the
1151         *       remote named in checkout.defaultRemote), then this is a
1152         *       short-hand to fork local <something> from that
1153         *       remote-tracking branch.
1154         *
1155         *   (c) Otherwise, if "--" is present, treat it like case (1).
1156         *
1157         *   (d) Otherwise :
1158         *       - if it's a reference, treat it like case (1)
1159         *       - else if it's a path, treat it like case (2)
1160         *       - else: fail.
1161         *
1162         * case 4: git checkout <something> <paths>
1163         *
1164         *   The first argument must not be ambiguous.
1165         *   - If it's *only* a reference, treat it like case (1).
1166         *   - If it's only a path, treat it like case (2).
1167         *   - else: fail.
1168         *
1169         */
1170        if (!argc)
1171                return 0;
1172
1173        arg = argv[0];
1174        dash_dash_pos = -1;
1175        for (i = 0; i < argc; i++) {
1176                if (!strcmp(argv[i], "--")) {
1177                        dash_dash_pos = i;
1178                        break;
1179                }
1180        }
1181        if (dash_dash_pos == 0)
1182                return 1; /* case (2) */
1183        else if (dash_dash_pos == 1)
1184                has_dash_dash = 1; /* case (3) or (1) */
1185        else if (dash_dash_pos >= 2)
1186                die(_("only one reference expected, %d given."), dash_dash_pos);
1187        opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1188
1189        if (!strcmp(arg, "-"))
1190                arg = "@{-1}";
1191
1192        if (get_oid_mb(arg, rev)) {
1193                /*
1194                 * Either case (3) or (4), with <something> not being
1195                 * a commit, or an attempt to use case (1) with an
1196                 * invalid ref.
1197                 *
1198                 * It's likely an error, but we need to find out if
1199                 * we should auto-create the branch, case (3).(b).
1200                 */
1201                int recover_with_dwim = dwim_new_local_branch_ok;
1202
1203                int could_be_checkout_paths = !has_dash_dash &&
1204                        check_filename(opts->prefix, arg);
1205
1206                if (!has_dash_dash && !no_wildcard(arg))
1207                        recover_with_dwim = 0;
1208
1209                /*
1210                 * Accept "git checkout foo" and "git checkout foo --"
1211                 * as candidates for dwim.
1212                 */
1213                if (!(argc == 1 && !has_dash_dash) &&
1214                    !(argc == 2 && has_dash_dash))
1215                        recover_with_dwim = 0;
1216
1217                if (recover_with_dwim) {
1218                        const char *remote = unique_tracking_name(arg, rev,
1219                                                                  dwim_remotes_matched);
1220                        if (remote) {
1221                                if (could_be_checkout_paths)
1222                                        die(_("'%s' could be both a local file and a tracking branch.\n"
1223                                              "Please use -- (and optionally --no-guess) to disambiguate"),
1224                                            arg);
1225                                *new_branch = arg;
1226                                arg = remote;
1227                                /* DWIMmed to create local branch, case (3).(b) */
1228                        } else {
1229                                recover_with_dwim = 0;
1230                        }
1231                }
1232
1233                if (!recover_with_dwim) {
1234                        if (has_dash_dash)
1235                                die(_("invalid reference: %s"), arg);
1236                        return argcount;
1237                }
1238        }
1239
1240        /* we can't end up being in (2) anymore, eat the argument */
1241        argcount++;
1242        argv++;
1243        argc--;
1244
1245        setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1246
1247        if (!opts->source_tree)                   /* case (1): want a tree */
1248                die(_("reference is not a tree: %s"), arg);
1249
1250        if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1251                /*
1252                 * Do not complain the most common case
1253                 *      git checkout branch
1254                 * even if there happen to be a file called 'branch';
1255                 * it would be extremely annoying.
1256                 */
1257                if (argc)
1258                        verify_non_filename(opts->prefix, arg);
1259        } else {
1260                argcount++;
1261                argv++;
1262                argc--;
1263        }
1264
1265        return argcount;
1266}
1267
1268static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1269{
1270        int status;
1271        struct strbuf branch_ref = STRBUF_INIT;
1272
1273        trace2_cmd_mode("unborn");
1274
1275        if (!opts->new_branch)
1276                die(_("You are on a branch yet to be born"));
1277        strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1278        status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1279        strbuf_release(&branch_ref);
1280        if (!opts->quiet)
1281                fprintf(stderr, _("Switched to a new branch '%s'\n"),
1282                        opts->new_branch);
1283        return status;
1284}
1285
1286static int checkout_branch(struct checkout_opts *opts,
1287                           struct branch_info *new_branch_info)
1288{
1289        if (opts->pathspec.nr)
1290                die(_("paths cannot be used with switching branches"));
1291
1292        if (opts->patch_mode)
1293                die(_("'%s' cannot be used with switching branches"),
1294                    "--patch");
1295
1296        if (!opts->overlay_mode)
1297                die(_("'%s' cannot be used with switching branches"),
1298                    "--no-overlay");
1299
1300        if (opts->writeout_stage)
1301                die(_("'%s' cannot be used with switching branches"),
1302                    "--ours/--theirs");
1303
1304        if (opts->force && opts->merge)
1305                die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1306
1307        if (opts->force_detach && opts->new_branch)
1308                die(_("'%s' cannot be used with '%s'"),
1309                    "--detach", "-b/-B/--orphan");
1310
1311        if (opts->new_orphan_branch) {
1312                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1313                        die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1314        } else if (opts->force_detach) {
1315                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1316                        die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1317        } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1318                opts->track = git_branch_track;
1319
1320        if (new_branch_info->name && !new_branch_info->commit)
1321                die(_("Cannot switch branch to a non-commit '%s'"),
1322                    new_branch_info->name);
1323
1324        if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1325            !opts->ignore_other_worktrees) {
1326                int flag;
1327                char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1328                if (head_ref &&
1329                    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1330                        die_if_checked_out(new_branch_info->path, 1);
1331                free(head_ref);
1332        }
1333
1334        if (!new_branch_info->commit && opts->new_branch) {
1335                struct object_id rev;
1336                int flag;
1337
1338                if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1339                    (flag & REF_ISSYMREF) && is_null_oid(&rev))
1340                        return switch_unborn_to_new_branch(opts);
1341        }
1342        return switch_branches(opts, new_branch_info);
1343}
1344
1345int cmd_checkout(int argc, const char **argv, const char *prefix)
1346{
1347        struct checkout_opts real_opts;
1348        struct checkout_opts *opts = &real_opts;
1349        struct branch_info new_branch_info;
1350        int dwim_new_local_branch;
1351        int dwim_remotes_matched = 0;
1352        struct option options[] = {
1353                OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1354                OPT_STRING('b', NULL, &opts->new_branch, N_("branch"),
1355                           N_("create and checkout a new branch")),
1356                OPT_STRING('B', NULL, &opts->new_branch_force, N_("branch"),
1357                           N_("create/reset and checkout a branch")),
1358                OPT_BOOL('l', NULL, &opts->new_branch_log, N_("create reflog for new branch")),
1359                OPT_BOOL(0, "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1360                OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1361                        BRANCH_TRACK_EXPLICIT),
1362                OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1363                OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1364                              N_("checkout our version for unmerged files"),
1365                              2, PARSE_OPT_NONEG),
1366                OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1367                              N_("checkout their version for unmerged files"),
1368                              3, PARSE_OPT_NONEG),
1369                OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1370                           PARSE_OPT_NOCOMPLETE),
1371                OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1372                OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1373                           N_("update ignored files (default)"),
1374                           PARSE_OPT_NOCOMPLETE),
1375                OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1376                           N_("conflict style (merge or diff3)")),
1377                OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1378                OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1379                         N_("do not limit pathspecs to sparse entries only")),
1380                OPT_BOOL(0, "no-guess", &opts->no_dwim_new_local_branch,
1381                         N_("do not second guess 'git checkout <no-such-branch>'")),
1382                OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1383                         N_("do not check if another worktree is holding the given ref")),
1384                { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1385                            "checkout", "control recursive updating of submodules",
1386                            PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1387                OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1388                OPT_BOOL(0, "overlay", &opts->overlay_mode, N_("use overlay mode (default)")),
1389                OPT_END(),
1390        };
1391
1392        memset(opts, 0, sizeof(*opts));
1393        memset(&new_branch_info, 0, sizeof(new_branch_info));
1394        opts->overwrite_ignore = 1;
1395        opts->prefix = prefix;
1396        opts->show_progress = -1;
1397        opts->overlay_mode = -1;
1398        opts->no_dwim_new_local_branch = 0;
1399
1400        git_config(git_checkout_config, opts);
1401
1402        opts->track = BRANCH_TRACK_UNSPECIFIED;
1403
1404        argc = parse_options(argc, argv, prefix, options, checkout_usage,
1405                             PARSE_OPT_KEEP_DASHDASH);
1406
1407        dwim_new_local_branch = !opts->no_dwim_new_local_branch;
1408        if (opts->show_progress < 0) {
1409                if (opts->quiet)
1410                        opts->show_progress = 0;
1411                else
1412                        opts->show_progress = isatty(2);
1413        }
1414
1415        if (opts->conflict_style) {
1416                opts->merge = 1; /* implied */
1417                git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1418        }
1419
1420        if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1421                die(_("-b, -B and --orphan are mutually exclusive"));
1422
1423        if (opts->overlay_mode == 1 && opts->patch_mode)
1424                die(_("-p and --overlay are mutually exclusive"));
1425
1426        /*
1427         * From here on, new_branch will contain the branch to be checked out,
1428         * and new_branch_force and new_orphan_branch will tell us which one of
1429         * -b/-B/--orphan is being used.
1430         */
1431        if (opts->new_branch_force)
1432                opts->new_branch = opts->new_branch_force;
1433
1434        if (opts->new_orphan_branch)
1435                opts->new_branch = opts->new_orphan_branch;
1436
1437        /* --track without -b/-B/--orphan should DWIM */
1438        if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1439                const char *argv0 = argv[0];
1440                if (!argc || !strcmp(argv0, "--"))
1441                        die(_("--track needs a branch name"));
1442                skip_prefix(argv0, "refs/", &argv0);
1443                skip_prefix(argv0, "remotes/", &argv0);
1444                argv0 = strchr(argv0, '/');
1445                if (!argv0 || !argv0[1])
1446                        die(_("missing branch name; try -b"));
1447                opts->new_branch = argv0 + 1;
1448        }
1449
1450        /*
1451         * Extract branch name from command line arguments, so
1452         * all that is left is pathspecs.
1453         *
1454         * Handle
1455         *
1456         *  1) git checkout <tree> -- [<paths>]
1457         *  2) git checkout -- [<paths>]
1458         *  3) git checkout <something> [<paths>]
1459         *
1460         * including "last branch" syntax and DWIM-ery for names of
1461         * remote branches, erroring out for invalid or ambiguous cases.
1462         */
1463        if (argc) {
1464                struct object_id rev;
1465                int dwim_ok =
1466                        !opts->patch_mode &&
1467                        dwim_new_local_branch &&
1468                        opts->track == BRANCH_TRACK_UNSPECIFIED &&
1469                        !opts->new_branch;
1470                int n = parse_branchname_arg(argc, argv, dwim_ok,
1471                                             &new_branch_info, opts, &rev,
1472                                             &dwim_remotes_matched);
1473                argv += n;
1474                argc -= n;
1475        }
1476
1477        if (argc) {
1478                parse_pathspec(&opts->pathspec, 0,
1479                               opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1480                               prefix, argv);
1481
1482                if (!opts->pathspec.nr)
1483                        die(_("invalid path specification"));
1484
1485                /*
1486                 * Try to give more helpful suggestion.
1487                 * new_branch && argc > 1 will be caught later.
1488                 */
1489                if (opts->new_branch && argc == 1)
1490                        die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1491                                argv[0], opts->new_branch);
1492
1493                if (opts->force_detach)
1494                        die(_("git checkout: --detach does not take a path argument '%s'"),
1495                            argv[0]);
1496
1497                if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1498                        die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1499                              "checking out of the index."));
1500        }
1501
1502        if (opts->new_branch) {
1503                struct strbuf buf = STRBUF_INIT;
1504
1505                if (opts->new_branch_force)
1506                        opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1507                else
1508                        opts->branch_exists =
1509                                validate_new_branchname(opts->new_branch, &buf, 0);
1510                strbuf_release(&buf);
1511        }
1512
1513        UNLEAK(opts);
1514        if (opts->patch_mode || opts->pathspec.nr) {
1515                int ret = checkout_paths(opts, new_branch_info.name);
1516                if (ret && dwim_remotes_matched > 1 &&
1517                    advice_checkout_ambiguous_remote_branch_name)
1518                        advise(_("'%s' matched more than one remote tracking branch.\n"
1519                                 "We found %d remotes with a reference that matched. So we fell back\n"
1520                                 "on trying to resolve the argument as a path, but failed there too!\n"
1521                                 "\n"
1522                                 "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1523                                 "you can do so by fully qualifying the name with the --track option:\n"
1524                                 "\n"
1525                                 "    git checkout --track origin/<name>\n"
1526                                 "\n"
1527                                 "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1528                                 "one remote, e.g. the 'origin' remote, consider setting\n"
1529                                 "checkout.defaultRemote=origin in your config."),
1530                               argv[0],
1531                               dwim_remotes_matched);
1532                return ret;
1533        } else {
1534                return checkout_branch(opts, &new_branch_info);
1535        }
1536}