builtin / checkout.con commit Merge branch 'dt/reflog-tests' (0188f32)
   1#include "builtin.h"
   2#include "lockfile.h"
   3#include "parse-options.h"
   4#include "refs.h"
   5#include "commit.h"
   6#include "tree.h"
   7#include "tree-walk.h"
   8#include "cache-tree.h"
   9#include "unpack-trees.h"
  10#include "dir.h"
  11#include "run-command.h"
  12#include "merge-recursive.h"
  13#include "branch.h"
  14#include "diff.h"
  15#include "revision.h"
  16#include "remote.h"
  17#include "blob.h"
  18#include "xdiff-interface.h"
  19#include "ll-merge.h"
  20#include "resolve-undo.h"
  21#include "submodule.h"
  22
  23static const char * const checkout_usage[] = {
  24        N_("git checkout [<options>] <branch>"),
  25        N_("git checkout [<options>] [<branch>] -- <file>..."),
  26        NULL,
  27};
  28
  29struct checkout_opts {
  30        int patch_mode;
  31        int quiet;
  32        int merge;
  33        int force;
  34        int force_detach;
  35        int writeout_stage;
  36        int overwrite_ignore;
  37        int ignore_skipworktree;
  38        int ignore_other_worktrees;
  39
  40        const char *new_branch;
  41        const char *new_branch_force;
  42        const char *new_orphan_branch;
  43        int new_branch_log;
  44        enum branch_track track;
  45        struct diff_options diff_options;
  46
  47        int branch_exists;
  48        const char *prefix;
  49        struct pathspec pathspec;
  50        struct tree *source_tree;
  51};
  52
  53static int post_checkout_hook(struct commit *old, struct commit *new,
  54                              int changed)
  55{
  56        return run_hook_le(NULL, "post-checkout",
  57                           sha1_to_hex(old ? old->object.sha1 : null_sha1),
  58                           sha1_to_hex(new ? new->object.sha1 : null_sha1),
  59                           changed ? "1" : "0", NULL);
  60        /* "new" can be NULL when checking out from the index before
  61           a commit exists. */
  62
  63}
  64
  65static int update_some(const unsigned char *sha1, struct strbuf *base,
  66                const char *pathname, unsigned mode, int stage, void *context)
  67{
  68        int len;
  69        struct cache_entry *ce;
  70        int pos;
  71
  72        if (S_ISDIR(mode))
  73                return READ_TREE_RECURSIVE;
  74
  75        len = base->len + strlen(pathname);
  76        ce = xcalloc(1, cache_entry_size(len));
  77        hashcpy(ce->sha1, sha1);
  78        memcpy(ce->name, base->buf, base->len);
  79        memcpy(ce->name + base->len, pathname, len - base->len);
  80        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  81        ce->ce_namelen = len;
  82        ce->ce_mode = create_ce_mode(mode);
  83
  84        /*
  85         * If the entry is the same as the current index, we can leave the old
  86         * entry in place. Whether it is UPTODATE or not, checkout_entry will
  87         * do the right thing.
  88         */
  89        pos = cache_name_pos(ce->name, ce->ce_namelen);
  90        if (pos >= 0) {
  91                struct cache_entry *old = active_cache[pos];
  92                if (ce->ce_mode == old->ce_mode &&
  93                    !hashcmp(ce->sha1, old->sha1)) {
  94                        old->ce_flags |= CE_UPDATE;
  95                        free(ce);
  96                        return 0;
  97                }
  98        }
  99
 100        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 101        return 0;
 102}
 103
 104static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 105{
 106        read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 107
 108        /* update the index with the given tree's info
 109         * for all args, expanding wildcards, and exit
 110         * with any non-zero return code.
 111         */
 112        return 0;
 113}
 114
 115static int skip_same_name(const struct cache_entry *ce, int pos)
 116{
 117        while (++pos < active_nr &&
 118               !strcmp(active_cache[pos]->name, ce->name))
 119                ; /* skip */
 120        return pos;
 121}
 122
 123static int check_stage(int stage, const struct cache_entry *ce, int pos)
 124{
 125        while (pos < active_nr &&
 126               !strcmp(active_cache[pos]->name, ce->name)) {
 127                if (ce_stage(active_cache[pos]) == stage)
 128                        return 0;
 129                pos++;
 130        }
 131        if (stage == 2)
 132                return error(_("path '%s' does not have our version"), ce->name);
 133        else
 134                return error(_("path '%s' does not have their version"), ce->name);
 135}
 136
 137static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 138{
 139        unsigned seen = 0;
 140        const char *name = ce->name;
 141
 142        while (pos < active_nr) {
 143                ce = active_cache[pos];
 144                if (strcmp(name, ce->name))
 145                        break;
 146                seen |= (1 << ce_stage(ce));
 147                pos++;
 148        }
 149        if ((stages & seen) != stages)
 150                return error(_("path '%s' does not have all necessary versions"),
 151                             name);
 152        return 0;
 153}
 154
 155static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 156                          struct checkout *state)
 157{
 158        while (pos < active_nr &&
 159               !strcmp(active_cache[pos]->name, ce->name)) {
 160                if (ce_stage(active_cache[pos]) == stage)
 161                        return checkout_entry(active_cache[pos], state, NULL);
 162                pos++;
 163        }
 164        if (stage == 2)
 165                return error(_("path '%s' does not have our version"), ce->name);
 166        else
 167                return error(_("path '%s' does not have their version"), ce->name);
 168}
 169
 170static int checkout_merged(int pos, struct checkout *state)
 171{
 172        struct cache_entry *ce = active_cache[pos];
 173        const char *path = ce->name;
 174        mmfile_t ancestor, ours, theirs;
 175        int status;
 176        unsigned char sha1[20];
 177        mmbuffer_t result_buf;
 178        unsigned char threeway[3][20];
 179        unsigned mode = 0;
 180
 181        memset(threeway, 0, sizeof(threeway));
 182        while (pos < active_nr) {
 183                int stage;
 184                stage = ce_stage(ce);
 185                if (!stage || strcmp(path, ce->name))
 186                        break;
 187                hashcpy(threeway[stage - 1], ce->sha1);
 188                if (stage == 2)
 189                        mode = create_ce_mode(ce->ce_mode);
 190                pos++;
 191                ce = active_cache[pos];
 192        }
 193        if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
 194                return error(_("path '%s' does not have necessary versions"), path);
 195
 196        read_mmblob(&ancestor, threeway[0]);
 197        read_mmblob(&ours, threeway[1]);
 198        read_mmblob(&theirs, threeway[2]);
 199
 200        /*
 201         * NEEDSWORK: re-create conflicts from merges with
 202         * merge.renormalize set, too
 203         */
 204        status = ll_merge(&result_buf, path, &ancestor, "base",
 205                          &ours, "ours", &theirs, "theirs", NULL);
 206        free(ancestor.ptr);
 207        free(ours.ptr);
 208        free(theirs.ptr);
 209        if (status < 0 || !result_buf.ptr) {
 210                free(result_buf.ptr);
 211                return error(_("path '%s': cannot merge"), path);
 212        }
 213
 214        /*
 215         * NEEDSWORK:
 216         * There is absolutely no reason to write this as a blob object
 217         * and create a phony cache entry just to leak.  This hack is
 218         * primarily to get to the write_entry() machinery that massages
 219         * the contents to work-tree format and writes out which only
 220         * allows it for a cache entry.  The code in write_entry() needs
 221         * to be refactored to allow us to feed a <buffer, size, mode>
 222         * instead of a cache entry.  Such a refactoring would help
 223         * merge_recursive as well (it also writes the merge result to the
 224         * object database even when it may contain conflicts).
 225         */
 226        if (write_sha1_file(result_buf.ptr, result_buf.size,
 227                            blob_type, sha1))
 228                die(_("Unable to add merge result for '%s'"), path);
 229        ce = make_cache_entry(mode, sha1, path, 2, 0);
 230        if (!ce)
 231                die(_("make_cache_entry failed for path '%s'"), path);
 232        status = checkout_entry(ce, state, NULL);
 233        return status;
 234}
 235
 236static int checkout_paths(const struct checkout_opts *opts,
 237                          const char *revision)
 238{
 239        int pos;
 240        struct checkout state;
 241        static char *ps_matched;
 242        unsigned char rev[20];
 243        int flag;
 244        struct commit *head;
 245        int errs = 0;
 246        struct lock_file *lock_file;
 247
 248        if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 249                die(_("'%s' cannot be used with updating paths"), "--track");
 250
 251        if (opts->new_branch_log)
 252                die(_("'%s' cannot be used with updating paths"), "-l");
 253
 254        if (opts->force && opts->patch_mode)
 255                die(_("'%s' cannot be used with updating paths"), "-f");
 256
 257        if (opts->force_detach)
 258                die(_("'%s' cannot be used with updating paths"), "--detach");
 259
 260        if (opts->merge && opts->patch_mode)
 261                die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 262
 263        if (opts->force && opts->merge)
 264                die(_("'%s' cannot be used with %s"), "-f", "-m");
 265
 266        if (opts->new_branch)
 267                die(_("Cannot update paths and switch to branch '%s' at the same time."),
 268                    opts->new_branch);
 269
 270        if (opts->patch_mode)
 271                return run_add_interactive(revision, "--patch=checkout",
 272                                           &opts->pathspec);
 273
 274        lock_file = xcalloc(1, sizeof(struct lock_file));
 275
 276        hold_locked_index(lock_file, 1);
 277        if (read_cache_preload(&opts->pathspec) < 0)
 278                return error(_("corrupt index file"));
 279
 280        if (opts->source_tree)
 281                read_tree_some(opts->source_tree, &opts->pathspec);
 282
 283        ps_matched = xcalloc(1, opts->pathspec.nr);
 284
 285        /*
 286         * Make sure all pathspecs participated in locating the paths
 287         * to be checked out.
 288         */
 289        for (pos = 0; pos < active_nr; pos++) {
 290                struct cache_entry *ce = active_cache[pos];
 291                ce->ce_flags &= ~CE_MATCHED;
 292                if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 293                        continue;
 294                if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 295                        /*
 296                         * "git checkout tree-ish -- path", but this entry
 297                         * is in the original index; it will not be checked
 298                         * out to the working tree and it does not matter
 299                         * if pathspec matched this entry.  We will not do
 300                         * anything to this entry at all.
 301                         */
 302                        continue;
 303                /*
 304                 * Either this entry came from the tree-ish we are
 305                 * checking the paths out of, or we are checking out
 306                 * of the index.
 307                 *
 308                 * If it comes from the tree-ish, we already know it
 309                 * matches the pathspec and could just stamp
 310                 * CE_MATCHED to it from update_some(). But we still
 311                 * need ps_matched and read_tree_recursive (and
 312                 * eventually tree_entry_interesting) cannot fill
 313                 * ps_matched yet. Once it can, we can avoid calling
 314                 * match_pathspec() for _all_ entries when
 315                 * opts->source_tree != NULL.
 316                 */
 317                if (ce_path_match(ce, &opts->pathspec, ps_matched))
 318                        ce->ce_flags |= CE_MATCHED;
 319        }
 320
 321        if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 322                free(ps_matched);
 323                return 1;
 324        }
 325        free(ps_matched);
 326
 327        /* "checkout -m path" to recreate conflicted state */
 328        if (opts->merge)
 329                unmerge_marked_index(&the_index);
 330
 331        /* Any unmerged paths? */
 332        for (pos = 0; pos < active_nr; pos++) {
 333                const struct cache_entry *ce = active_cache[pos];
 334                if (ce->ce_flags & CE_MATCHED) {
 335                        if (!ce_stage(ce))
 336                                continue;
 337                        if (opts->force) {
 338                                warning(_("path '%s' is unmerged"), ce->name);
 339                        } else if (opts->writeout_stage) {
 340                                errs |= check_stage(opts->writeout_stage, ce, pos);
 341                        } else if (opts->merge) {
 342                                errs |= check_stages((1<<2) | (1<<3), ce, pos);
 343                        } else {
 344                                errs = 1;
 345                                error(_("path '%s' is unmerged"), ce->name);
 346                        }
 347                        pos = skip_same_name(ce, pos) - 1;
 348                }
 349        }
 350        if (errs)
 351                return 1;
 352
 353        /* Now we are committed to check them out */
 354        memset(&state, 0, sizeof(state));
 355        state.force = 1;
 356        state.refresh_cache = 1;
 357        state.istate = &the_index;
 358        for (pos = 0; pos < active_nr; pos++) {
 359                struct cache_entry *ce = active_cache[pos];
 360                if (ce->ce_flags & CE_MATCHED) {
 361                        if (!ce_stage(ce)) {
 362                                errs |= checkout_entry(ce, &state, NULL);
 363                                continue;
 364                        }
 365                        if (opts->writeout_stage)
 366                                errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 367                        else if (opts->merge)
 368                                errs |= checkout_merged(pos, &state);
 369                        pos = skip_same_name(ce, pos) - 1;
 370                }
 371        }
 372
 373        if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 374                die(_("unable to write new index file"));
 375
 376        read_ref_full("HEAD", 0, rev, &flag);
 377        head = lookup_commit_reference_gently(rev, 1);
 378
 379        errs |= post_checkout_hook(head, head, 0);
 380        return errs;
 381}
 382
 383static void show_local_changes(struct object *head,
 384                               const struct diff_options *opts)
 385{
 386        struct rev_info rev;
 387        /* I think we want full paths, even if we're in a subdirectory. */
 388        init_revisions(&rev, NULL);
 389        rev.diffopt.flags = opts->flags;
 390        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 391        diff_setup_done(&rev.diffopt);
 392        add_pending_object(&rev, head, NULL);
 393        run_diff_index(&rev, 0);
 394}
 395
 396static void describe_detached_head(const char *msg, struct commit *commit)
 397{
 398        struct strbuf sb = STRBUF_INIT;
 399        if (!parse_commit(commit))
 400                pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 401        fprintf(stderr, "%s %s... %s\n", msg,
 402                find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 403        strbuf_release(&sb);
 404}
 405
 406static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 407                      int worktree, int *writeout_error)
 408{
 409        struct unpack_trees_options opts;
 410        struct tree_desc tree_desc;
 411
 412        memset(&opts, 0, sizeof(opts));
 413        opts.head_idx = -1;
 414        opts.update = worktree;
 415        opts.skip_unmerged = !worktree;
 416        opts.reset = 1;
 417        opts.merge = 1;
 418        opts.fn = oneway_merge;
 419        opts.verbose_update = !o->quiet && isatty(2);
 420        opts.src_index = &the_index;
 421        opts.dst_index = &the_index;
 422        parse_tree(tree);
 423        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 424        switch (unpack_trees(1, &tree_desc, &opts)) {
 425        case -2:
 426                *writeout_error = 1;
 427                /*
 428                 * We return 0 nevertheless, as the index is all right
 429                 * and more importantly we have made best efforts to
 430                 * update paths in the work tree, and we cannot revert
 431                 * them.
 432                 */
 433        case 0:
 434                return 0;
 435        default:
 436                return 128;
 437        }
 438}
 439
 440struct branch_info {
 441        const char *name; /* The short name used */
 442        const char *path; /* The full name of a real branch */
 443        struct commit *commit; /* The named commit */
 444        /*
 445         * if not null the branch is detached because it's already
 446         * checked out in this checkout
 447         */
 448        char *checkout;
 449};
 450
 451static void setup_branch_path(struct branch_info *branch)
 452{
 453        struct strbuf buf = STRBUF_INIT;
 454
 455        strbuf_branchname(&buf, branch->name);
 456        if (strcmp(buf.buf, branch->name))
 457                branch->name = xstrdup(buf.buf);
 458        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 459        branch->path = strbuf_detach(&buf, NULL);
 460}
 461
 462static int merge_working_tree(const struct checkout_opts *opts,
 463                              struct branch_info *old,
 464                              struct branch_info *new,
 465                              int *writeout_error)
 466{
 467        int ret;
 468        struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 469
 470        hold_locked_index(lock_file, 1);
 471        if (read_cache_preload(NULL) < 0)
 472                return error(_("corrupt index file"));
 473
 474        resolve_undo_clear();
 475        if (opts->force) {
 476                ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 477                if (ret)
 478                        return ret;
 479        } else {
 480                struct tree_desc trees[2];
 481                struct tree *tree;
 482                struct unpack_trees_options topts;
 483
 484                memset(&topts, 0, sizeof(topts));
 485                topts.head_idx = -1;
 486                topts.src_index = &the_index;
 487                topts.dst_index = &the_index;
 488
 489                setup_unpack_trees_porcelain(&topts, "checkout");
 490
 491                refresh_cache(REFRESH_QUIET);
 492
 493                if (unmerged_cache()) {
 494                        error(_("you need to resolve your current index first"));
 495                        return 1;
 496                }
 497
 498                /* 2-way merge to the new branch */
 499                topts.initial_checkout = is_cache_unborn();
 500                topts.update = 1;
 501                topts.merge = 1;
 502                topts.gently = opts->merge && old->commit;
 503                topts.verbose_update = !opts->quiet && isatty(2);
 504                topts.fn = twoway_merge;
 505                if (opts->overwrite_ignore) {
 506                        topts.dir = xcalloc(1, sizeof(*topts.dir));
 507                        topts.dir->flags |= DIR_SHOW_IGNORED;
 508                        setup_standard_excludes(topts.dir);
 509                }
 510                tree = parse_tree_indirect(old->commit ?
 511                                           old->commit->object.sha1 :
 512                                           EMPTY_TREE_SHA1_BIN);
 513                init_tree_desc(&trees[0], tree->buffer, tree->size);
 514                tree = parse_tree_indirect(new->commit->object.sha1);
 515                init_tree_desc(&trees[1], tree->buffer, tree->size);
 516
 517                ret = unpack_trees(2, trees, &topts);
 518                if (ret == -1) {
 519                        /*
 520                         * Unpack couldn't do a trivial merge; either
 521                         * give up or do a real merge, depending on
 522                         * whether the merge flag was used.
 523                         */
 524                        struct tree *result;
 525                        struct tree *work;
 526                        struct merge_options o;
 527                        if (!opts->merge)
 528                                return 1;
 529
 530                        /*
 531                         * Without old->commit, the below is the same as
 532                         * the two-tree unpack we already tried and failed.
 533                         */
 534                        if (!old->commit)
 535                                return 1;
 536
 537                        /* Do more real merge */
 538
 539                        /*
 540                         * We update the index fully, then write the
 541                         * tree from the index, then merge the new
 542                         * branch with the current tree, with the old
 543                         * branch as the base. Then we reset the index
 544                         * (but not the working tree) to the new
 545                         * branch, leaving the working tree as the
 546                         * merged version, but skipping unmerged
 547                         * entries in the index.
 548                         */
 549
 550                        add_files_to_cache(NULL, NULL, 0);
 551                        /*
 552                         * NEEDSWORK: carrying over local changes
 553                         * when branches have different end-of-line
 554                         * normalization (or clean+smudge rules) is
 555                         * a pain; plumb in an option to set
 556                         * o.renormalize?
 557                         */
 558                        init_merge_options(&o);
 559                        o.verbosity = 0;
 560                        work = write_tree_from_memory(&o);
 561
 562                        ret = reset_tree(new->commit->tree, opts, 1,
 563                                         writeout_error);
 564                        if (ret)
 565                                return ret;
 566                        o.ancestor = old->name;
 567                        o.branch1 = new->name;
 568                        o.branch2 = "local";
 569                        merge_trees(&o, new->commit->tree, work,
 570                                old->commit->tree, &result);
 571                        ret = reset_tree(new->commit->tree, opts, 0,
 572                                         writeout_error);
 573                        if (ret)
 574                                return ret;
 575                }
 576        }
 577
 578        if (!active_cache_tree)
 579                active_cache_tree = cache_tree();
 580
 581        if (!cache_tree_fully_valid(active_cache_tree))
 582                cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 583
 584        if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 585                die(_("unable to write new index file"));
 586
 587        if (!opts->force && !opts->quiet)
 588                show_local_changes(&new->commit->object, &opts->diff_options);
 589
 590        return 0;
 591}
 592
 593static void report_tracking(struct branch_info *new)
 594{
 595        struct strbuf sb = STRBUF_INIT;
 596        struct branch *branch = branch_get(new->name);
 597
 598        if (!format_tracking_info(branch, &sb))
 599                return;
 600        fputs(sb.buf, stdout);
 601        strbuf_release(&sb);
 602}
 603
 604static void update_refs_for_switch(const struct checkout_opts *opts,
 605                                   struct branch_info *old,
 606                                   struct branch_info *new)
 607{
 608        struct strbuf msg = STRBUF_INIT;
 609        const char *old_desc, *reflog_msg;
 610        if (opts->new_branch) {
 611                if (opts->new_orphan_branch) {
 612                        if (opts->new_branch_log && !log_all_ref_updates) {
 613                                int ret;
 614                                char *refname;
 615                                struct strbuf err = STRBUF_INIT;
 616
 617                                refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 618                                ret = safe_create_reflog(refname, 1, &err);
 619                                free(refname);
 620                                if (ret) {
 621                                        fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 622                                                opts->new_orphan_branch, err.buf);
 623                                        strbuf_release(&err);
 624                                        return;
 625                                }
 626                                strbuf_release(&err);
 627                        }
 628                }
 629                else
 630                        create_branch(old->name, opts->new_branch, new->name,
 631                                      opts->new_branch_force ? 1 : 0,
 632                                      opts->new_branch_log,
 633                                      opts->new_branch_force ? 1 : 0,
 634                                      opts->quiet,
 635                                      opts->track);
 636                new->name = opts->new_branch;
 637                setup_branch_path(new);
 638        }
 639
 640        old_desc = old->name;
 641        if (!old_desc && old->commit)
 642                old_desc = sha1_to_hex(old->commit->object.sha1);
 643
 644        reflog_msg = getenv("GIT_REFLOG_ACTION");
 645        if (!reflog_msg)
 646                strbuf_addf(&msg, "checkout: moving from %s to %s",
 647                        old_desc ? old_desc : "(invalid)", new->name);
 648        else
 649                strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 650
 651        if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 652                /* Nothing to do. */
 653        } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 654                update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 655                           REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 656                if (!opts->quiet) {
 657                        if (old->path && advice_detached_head)
 658                                detach_advice(new->name);
 659                        describe_detached_head(_("HEAD is now at"), new->commit);
 660                }
 661        } else if (new->path) { /* Switch branches. */
 662                create_symref("HEAD", new->path, msg.buf);
 663                if (!opts->quiet) {
 664                        if (old->path && !strcmp(new->path, old->path)) {
 665                                if (opts->new_branch_force)
 666                                        fprintf(stderr, _("Reset branch '%s'\n"),
 667                                                new->name);
 668                                else
 669                                        fprintf(stderr, _("Already on '%s'\n"),
 670                                                new->name);
 671                        } else if (opts->new_branch) {
 672                                if (opts->branch_exists)
 673                                        fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 674                                else
 675                                        fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 676                        } else {
 677                                fprintf(stderr, _("Switched to branch '%s'\n"),
 678                                        new->name);
 679                        }
 680                }
 681                if (old->path && old->name) {
 682                        if (!ref_exists(old->path) && reflog_exists(old->path))
 683                                delete_reflog(old->path);
 684                }
 685        }
 686        remove_branch_state();
 687        strbuf_release(&msg);
 688        if (!opts->quiet &&
 689            (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 690                report_tracking(new);
 691}
 692
 693static int add_pending_uninteresting_ref(const char *refname,
 694                                         const struct object_id *oid,
 695                                         int flags, void *cb_data)
 696{
 697        add_pending_sha1(cb_data, refname, oid->hash, UNINTERESTING);
 698        return 0;
 699}
 700
 701static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 702{
 703        strbuf_addstr(sb, "  ");
 704        strbuf_addstr(sb,
 705                find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 706        strbuf_addch(sb, ' ');
 707        if (!parse_commit(commit))
 708                pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 709        strbuf_addch(sb, '\n');
 710}
 711
 712#define ORPHAN_CUTOFF 4
 713static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 714{
 715        struct commit *c, *last = NULL;
 716        struct strbuf sb = STRBUF_INIT;
 717        int lost = 0;
 718        while ((c = get_revision(revs)) != NULL) {
 719                if (lost < ORPHAN_CUTOFF)
 720                        describe_one_orphan(&sb, c);
 721                last = c;
 722                lost++;
 723        }
 724        if (ORPHAN_CUTOFF < lost) {
 725                int more = lost - ORPHAN_CUTOFF;
 726                if (more == 1)
 727                        describe_one_orphan(&sb, last);
 728                else
 729                        strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 730        }
 731
 732        fprintf(stderr,
 733                Q_(
 734                /* The singular version */
 735                "Warning: you are leaving %d commit behind, "
 736                "not connected to\n"
 737                "any of your branches:\n\n"
 738                "%s\n",
 739                /* The plural version */
 740                "Warning: you are leaving %d commits behind, "
 741                "not connected to\n"
 742                "any of your branches:\n\n"
 743                "%s\n",
 744                /* Give ngettext() the count */
 745                lost),
 746                lost,
 747                sb.buf);
 748        strbuf_release(&sb);
 749
 750        if (advice_detached_head)
 751                fprintf(stderr,
 752                        Q_(
 753                        /* The singular version */
 754                        "If you want to keep it by creating a new branch, "
 755                        "this may be a good time\nto do so with:\n\n"
 756                        " git branch <new-branch-name> %s\n\n",
 757                        /* The plural version */
 758                        "If you want to keep them by creating a new branch, "
 759                        "this may be a good time\nto do so with:\n\n"
 760                        " git branch <new-branch-name> %s\n\n",
 761                        /* Give ngettext() the count */
 762                        lost),
 763                        find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 764}
 765
 766/*
 767 * We are about to leave commit that was at the tip of a detached
 768 * HEAD.  If it is not reachable from any ref, this is the last chance
 769 * for the user to do so without resorting to reflog.
 770 */
 771static void orphaned_commit_warning(struct commit *old, struct commit *new)
 772{
 773        struct rev_info revs;
 774        struct object *object = &old->object;
 775        struct object_array refs;
 776
 777        init_revisions(&revs, NULL);
 778        setup_revisions(0, NULL, &revs, NULL);
 779
 780        object->flags &= ~UNINTERESTING;
 781        add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 782
 783        for_each_ref(add_pending_uninteresting_ref, &revs);
 784        add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 785
 786        refs = revs.pending;
 787        revs.leak_pending = 1;
 788
 789        if (prepare_revision_walk(&revs))
 790                die(_("internal error in revision walk"));
 791        if (!(old->object.flags & UNINTERESTING))
 792                suggest_reattach(old, &revs);
 793        else
 794                describe_detached_head(_("Previous HEAD position was"), old);
 795
 796        clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 797        free(refs.objects);
 798}
 799
 800static int switch_branches(const struct checkout_opts *opts,
 801                           struct branch_info *new)
 802{
 803        int ret = 0;
 804        struct branch_info old;
 805        void *path_to_free;
 806        unsigned char rev[20];
 807        int flag, writeout_error = 0;
 808        memset(&old, 0, sizeof(old));
 809        old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 810        old.commit = lookup_commit_reference_gently(rev, 1);
 811        if (!(flag & REF_ISSYMREF))
 812                old.path = NULL;
 813
 814        if (old.path)
 815                skip_prefix(old.path, "refs/heads/", &old.name);
 816
 817        if (!new->name) {
 818                new->name = "HEAD";
 819                new->commit = old.commit;
 820                if (!new->commit)
 821                        die(_("You are on a branch yet to be born"));
 822                parse_commit_or_die(new->commit);
 823        }
 824
 825        ret = merge_working_tree(opts, &old, new, &writeout_error);
 826        if (ret) {
 827                free(path_to_free);
 828                return ret;
 829        }
 830
 831        if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 832                orphaned_commit_warning(old.commit, new->commit);
 833
 834        update_refs_for_switch(opts, &old, new);
 835
 836        ret = post_checkout_hook(old.commit, new->commit, 1);
 837        free(path_to_free);
 838        return ret || writeout_error;
 839}
 840
 841static int git_checkout_config(const char *var, const char *value, void *cb)
 842{
 843        if (!strcmp(var, "diff.ignoresubmodules")) {
 844                struct checkout_opts *opts = cb;
 845                handle_ignore_submodules_arg(&opts->diff_options, value);
 846                return 0;
 847        }
 848
 849        if (starts_with(var, "submodule."))
 850                return parse_submodule_config_option(var, value);
 851
 852        return git_xmerge_config(var, value, NULL);
 853}
 854
 855struct tracking_name_data {
 856        /* const */ char *src_ref;
 857        char *dst_ref;
 858        unsigned char *dst_sha1;
 859        int unique;
 860};
 861
 862static int check_tracking_name(struct remote *remote, void *cb_data)
 863{
 864        struct tracking_name_data *cb = cb_data;
 865        struct refspec query;
 866        memset(&query, 0, sizeof(struct refspec));
 867        query.src = cb->src_ref;
 868        if (remote_find_tracking(remote, &query) ||
 869            get_sha1(query.dst, cb->dst_sha1)) {
 870                free(query.dst);
 871                return 0;
 872        }
 873        if (cb->dst_ref) {
 874                free(query.dst);
 875                cb->unique = 0;
 876                return 0;
 877        }
 878        cb->dst_ref = query.dst;
 879        return 0;
 880}
 881
 882static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 883{
 884        struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 885        char src_ref[PATH_MAX];
 886        snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 887        cb_data.src_ref = src_ref;
 888        cb_data.dst_sha1 = sha1;
 889        for_each_remote(check_tracking_name, &cb_data);
 890        if (cb_data.unique)
 891                return cb_data.dst_ref;
 892        free(cb_data.dst_ref);
 893        return NULL;
 894}
 895
 896static int parse_branchname_arg(int argc, const char **argv,
 897                                int dwim_new_local_branch_ok,
 898                                struct branch_info *new,
 899                                struct checkout_opts *opts,
 900                                unsigned char rev[20])
 901{
 902        struct tree **source_tree = &opts->source_tree;
 903        const char **new_branch = &opts->new_branch;
 904        int argcount = 0;
 905        unsigned char branch_rev[20];
 906        const char *arg;
 907        int dash_dash_pos;
 908        int has_dash_dash = 0;
 909        int i;
 910
 911        /*
 912         * case 1: git checkout <ref> -- [<paths>]
 913         *
 914         *   <ref> must be a valid tree, everything after the '--' must be
 915         *   a path.
 916         *
 917         * case 2: git checkout -- [<paths>]
 918         *
 919         *   everything after the '--' must be paths.
 920         *
 921         * case 3: git checkout <something> [--]
 922         *
 923         *   (a) If <something> is a commit, that is to
 924         *       switch to the branch or detach HEAD at it.  As a special case,
 925         *       if <something> is A...B (missing A or B means HEAD but you can
 926         *       omit at most one side), and if there is a unique merge base
 927         *       between A and B, A...B names that merge base.
 928         *
 929         *   (b) If <something> is _not_ a commit, either "--" is present
 930         *       or <something> is not a path, no -t or -b was given, and
 931         *       and there is a tracking branch whose name is <something>
 932         *       in one and only one remote, then this is a short-hand to
 933         *       fork local <something> from that remote-tracking branch.
 934         *
 935         *   (c) Otherwise, if "--" is present, treat it like case (1).
 936         *
 937         *   (d) Otherwise :
 938         *       - if it's a reference, treat it like case (1)
 939         *       - else if it's a path, treat it like case (2)
 940         *       - else: fail.
 941         *
 942         * case 4: git checkout <something> <paths>
 943         *
 944         *   The first argument must not be ambiguous.
 945         *   - If it's *only* a reference, treat it like case (1).
 946         *   - If it's only a path, treat it like case (2).
 947         *   - else: fail.
 948         *
 949         */
 950        if (!argc)
 951                return 0;
 952
 953        arg = argv[0];
 954        dash_dash_pos = -1;
 955        for (i = 0; i < argc; i++) {
 956                if (!strcmp(argv[i], "--")) {
 957                        dash_dash_pos = i;
 958                        break;
 959                }
 960        }
 961        if (dash_dash_pos == 0)
 962                return 1; /* case (2) */
 963        else if (dash_dash_pos == 1)
 964                has_dash_dash = 1; /* case (3) or (1) */
 965        else if (dash_dash_pos >= 2)
 966                die(_("only one reference expected, %d given."), dash_dash_pos);
 967
 968        if (!strcmp(arg, "-"))
 969                arg = "@{-1}";
 970
 971        if (get_sha1_mb(arg, rev)) {
 972                /*
 973                 * Either case (3) or (4), with <something> not being
 974                 * a commit, or an attempt to use case (1) with an
 975                 * invalid ref.
 976                 *
 977                 * It's likely an error, but we need to find out if
 978                 * we should auto-create the branch, case (3).(b).
 979                 */
 980                int recover_with_dwim = dwim_new_local_branch_ok;
 981
 982                if (check_filename(NULL, arg) && !has_dash_dash)
 983                        recover_with_dwim = 0;
 984                /*
 985                 * Accept "git checkout foo" and "git checkout foo --"
 986                 * as candidates for dwim.
 987                 */
 988                if (!(argc == 1 && !has_dash_dash) &&
 989                    !(argc == 2 && has_dash_dash))
 990                        recover_with_dwim = 0;
 991
 992                if (recover_with_dwim) {
 993                        const char *remote = unique_tracking_name(arg, rev);
 994                        if (remote) {
 995                                *new_branch = arg;
 996                                arg = remote;
 997                                /* DWIMmed to create local branch, case (3).(b) */
 998                        } else {
 999                                recover_with_dwim = 0;
1000                        }
1001                }
1002
1003                if (!recover_with_dwim) {
1004                        if (has_dash_dash)
1005                                die(_("invalid reference: %s"), arg);
1006                        return argcount;
1007                }
1008        }
1009
1010        /* we can't end up being in (2) anymore, eat the argument */
1011        argcount++;
1012        argv++;
1013        argc--;
1014
1015        new->name = arg;
1016        setup_branch_path(new);
1017
1018        if (!check_refname_format(new->path, 0) &&
1019            !read_ref(new->path, branch_rev))
1020                hashcpy(rev, branch_rev);
1021        else
1022                new->path = NULL; /* not an existing branch */
1023
1024        new->commit = lookup_commit_reference_gently(rev, 1);
1025        if (!new->commit) {
1026                /* not a commit */
1027                *source_tree = parse_tree_indirect(rev);
1028        } else {
1029                parse_commit_or_die(new->commit);
1030                *source_tree = new->commit->tree;
1031        }
1032
1033        if (!*source_tree)                   /* case (1): want a tree */
1034                die(_("reference is not a tree: %s"), arg);
1035        if (!has_dash_dash) {/* case (3).(d) -> (1) */
1036                /*
1037                 * Do not complain the most common case
1038                 *      git checkout branch
1039                 * even if there happen to be a file called 'branch';
1040                 * it would be extremely annoying.
1041                 */
1042                if (argc)
1043                        verify_non_filename(NULL, arg);
1044        } else {
1045                argcount++;
1046                argv++;
1047                argc--;
1048        }
1049
1050        return argcount;
1051}
1052
1053static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1054{
1055        int status;
1056        struct strbuf branch_ref = STRBUF_INIT;
1057
1058        if (!opts->new_branch)
1059                die(_("You are on a branch yet to be born"));
1060        strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1061        status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1062        strbuf_release(&branch_ref);
1063        if (!opts->quiet)
1064                fprintf(stderr, _("Switched to a new branch '%s'\n"),
1065                        opts->new_branch);
1066        return status;
1067}
1068
1069static int checkout_branch(struct checkout_opts *opts,
1070                           struct branch_info *new)
1071{
1072        if (opts->pathspec.nr)
1073                die(_("paths cannot be used with switching branches"));
1074
1075        if (opts->patch_mode)
1076                die(_("'%s' cannot be used with switching branches"),
1077                    "--patch");
1078
1079        if (opts->writeout_stage)
1080                die(_("'%s' cannot be used with switching branches"),
1081                    "--ours/--theirs");
1082
1083        if (opts->force && opts->merge)
1084                die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1085
1086        if (opts->force_detach && opts->new_branch)
1087                die(_("'%s' cannot be used with '%s'"),
1088                    "--detach", "-b/-B/--orphan");
1089
1090        if (opts->new_orphan_branch) {
1091                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1092                        die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1093        } else if (opts->force_detach) {
1094                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1095                        die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1096        } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1097                opts->track = git_branch_track;
1098
1099        if (new->name && !new->commit)
1100                die(_("Cannot switch branch to a non-commit '%s'"),
1101                    new->name);
1102
1103        if (new->path && !opts->force_detach && !opts->new_branch &&
1104            !opts->ignore_other_worktrees) {
1105                unsigned char sha1[20];
1106                int flag;
1107                char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
1108                if (head_ref &&
1109                    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1110                        die_if_checked_out(new->path);
1111                free(head_ref);
1112        }
1113
1114        if (!new->commit && opts->new_branch) {
1115                unsigned char rev[20];
1116                int flag;
1117
1118                if (!read_ref_full("HEAD", 0, rev, &flag) &&
1119                    (flag & REF_ISSYMREF) && is_null_sha1(rev))
1120                        return switch_unborn_to_new_branch(opts);
1121        }
1122        return switch_branches(opts, new);
1123}
1124
1125int cmd_checkout(int argc, const char **argv, const char *prefix)
1126{
1127        struct checkout_opts opts;
1128        struct branch_info new;
1129        char *conflict_style = NULL;
1130        int dwim_new_local_branch = 1;
1131        struct option options[] = {
1132                OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1133                OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1134                           N_("create and checkout a new branch")),
1135                OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1136                           N_("create/reset and checkout a branch")),
1137                OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1138                OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1139                OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1140                        BRANCH_TRACK_EXPLICIT),
1141                OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1142                OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1143                            2),
1144                OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1145                            3),
1146                OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1147                OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1148                OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1149                OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1150                           N_("conflict style (merge or diff3)")),
1151                OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1152                OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1153                         N_("do not limit pathspecs to sparse entries only")),
1154                OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1155                                N_("second guess 'git checkout <no-such-branch>'")),
1156                OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1157                         N_("do not check if another worktree is holding the given ref")),
1158                OPT_END(),
1159        };
1160
1161        memset(&opts, 0, sizeof(opts));
1162        memset(&new, 0, sizeof(new));
1163        opts.overwrite_ignore = 1;
1164        opts.prefix = prefix;
1165
1166        gitmodules_config();
1167        git_config(git_checkout_config, &opts);
1168
1169        opts.track = BRANCH_TRACK_UNSPECIFIED;
1170
1171        argc = parse_options(argc, argv, prefix, options, checkout_usage,
1172                             PARSE_OPT_KEEP_DASHDASH);
1173
1174        if (conflict_style) {
1175                opts.merge = 1; /* implied */
1176                git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1177        }
1178
1179        if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1180                die(_("-b, -B and --orphan are mutually exclusive"));
1181
1182        /*
1183         * From here on, new_branch will contain the branch to be checked out,
1184         * and new_branch_force and new_orphan_branch will tell us which one of
1185         * -b/-B/--orphan is being used.
1186         */
1187        if (opts.new_branch_force)
1188                opts.new_branch = opts.new_branch_force;
1189
1190        if (opts.new_orphan_branch)
1191                opts.new_branch = opts.new_orphan_branch;
1192
1193        /* --track without -b/-B/--orphan should DWIM */
1194        if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1195                const char *argv0 = argv[0];
1196                if (!argc || !strcmp(argv0, "--"))
1197                        die (_("--track needs a branch name"));
1198                skip_prefix(argv0, "refs/", &argv0);
1199                skip_prefix(argv0, "remotes/", &argv0);
1200                argv0 = strchr(argv0, '/');
1201                if (!argv0 || !argv0[1])
1202                        die (_("Missing branch name; try -b"));
1203                opts.new_branch = argv0 + 1;
1204        }
1205
1206        /*
1207         * Extract branch name from command line arguments, so
1208         * all that is left is pathspecs.
1209         *
1210         * Handle
1211         *
1212         *  1) git checkout <tree> -- [<paths>]
1213         *  2) git checkout -- [<paths>]
1214         *  3) git checkout <something> [<paths>]
1215         *
1216         * including "last branch" syntax and DWIM-ery for names of
1217         * remote branches, erroring out for invalid or ambiguous cases.
1218         */
1219        if (argc) {
1220                unsigned char rev[20];
1221                int dwim_ok =
1222                        !opts.patch_mode &&
1223                        dwim_new_local_branch &&
1224                        opts.track == BRANCH_TRACK_UNSPECIFIED &&
1225                        !opts.new_branch;
1226                int n = parse_branchname_arg(argc, argv, dwim_ok,
1227                                             &new, &opts, rev);
1228                argv += n;
1229                argc -= n;
1230        }
1231
1232        if (argc) {
1233                parse_pathspec(&opts.pathspec, 0,
1234                               opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1235                               prefix, argv);
1236
1237                if (!opts.pathspec.nr)
1238                        die(_("invalid path specification"));
1239
1240                /*
1241                 * Try to give more helpful suggestion.
1242                 * new_branch && argc > 1 will be caught later.
1243                 */
1244                if (opts.new_branch && argc == 1)
1245                        die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1246                              "Did you intend to checkout '%s' which can not be resolved as commit?"),
1247                            opts.new_branch, argv[0]);
1248
1249                if (opts.force_detach)
1250                        die(_("git checkout: --detach does not take a path argument '%s'"),
1251                            argv[0]);
1252
1253                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1254                        die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1255                              "checking out of the index."));
1256        }
1257
1258        if (opts.new_branch) {
1259                struct strbuf buf = STRBUF_INIT;
1260
1261                opts.branch_exists =
1262                        validate_new_branchname(opts.new_branch, &buf,
1263                                                !!opts.new_branch_force,
1264                                                !!opts.new_branch_force);
1265
1266                strbuf_release(&buf);
1267        }
1268
1269        if (opts.patch_mode || opts.pathspec.nr)
1270                return checkout_paths(&opts, new.name);
1271        else
1272                return checkout_branch(&opts, &new);
1273}