builtin-checkout.con commit Add branch --set-upstream (4fc5006)
   1#include "cache.h"
   2#include "builtin.h"
   3#include "parse-options.h"
   4#include "refs.h"
   5#include "commit.h"
   6#include "tree.h"
   7#include "tree-walk.h"
   8#include "cache-tree.h"
   9#include "unpack-trees.h"
  10#include "dir.h"
  11#include "run-command.h"
  12#include "merge-recursive.h"
  13#include "branch.h"
  14#include "diff.h"
  15#include "revision.h"
  16#include "remote.h"
  17#include "blob.h"
  18#include "xdiff-interface.h"
  19#include "ll-merge.h"
  20
  21static const char * const checkout_usage[] = {
  22        "git checkout [options] <branch>",
  23        "git checkout [options] [<branch>] -- <file>...",
  24        NULL,
  25};
  26
  27struct checkout_opts {
  28        int quiet;
  29        int merge;
  30        int force;
  31        int writeout_stage;
  32        int writeout_error;
  33
  34        const char *new_branch;
  35        int new_branch_log;
  36        enum branch_track track;
  37};
  38
  39static int post_checkout_hook(struct commit *old, struct commit *new,
  40                              int changed)
  41{
  42        return run_hook(NULL, "post-checkout",
  43                        sha1_to_hex(old ? old->object.sha1 : null_sha1),
  44                        sha1_to_hex(new ? new->object.sha1 : null_sha1),
  45                        changed ? "1" : "0", NULL);
  46        /* "new" can be NULL when checking out from the index before
  47           a commit exists. */
  48
  49}
  50
  51static int update_some(const unsigned char *sha1, const char *base, int baselen,
  52                const char *pathname, unsigned mode, int stage, void *context)
  53{
  54        int len;
  55        struct cache_entry *ce;
  56
  57        if (S_ISDIR(mode))
  58                return READ_TREE_RECURSIVE;
  59
  60        len = baselen + strlen(pathname);
  61        ce = xcalloc(1, cache_entry_size(len));
  62        hashcpy(ce->sha1, sha1);
  63        memcpy(ce->name, base, baselen);
  64        memcpy(ce->name + baselen, pathname, len - baselen);
  65        ce->ce_flags = create_ce_flags(len, 0);
  66        ce->ce_mode = create_ce_mode(mode);
  67        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
  68        return 0;
  69}
  70
  71static int read_tree_some(struct tree *tree, const char **pathspec)
  72{
  73        read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
  74
  75        /* update the index with the given tree's info
  76         * for all args, expanding wildcards, and exit
  77         * with any non-zero return code.
  78         */
  79        return 0;
  80}
  81
  82static int skip_same_name(struct cache_entry *ce, int pos)
  83{
  84        while (++pos < active_nr &&
  85               !strcmp(active_cache[pos]->name, ce->name))
  86                ; /* skip */
  87        return pos;
  88}
  89
  90static int check_stage(int stage, struct cache_entry *ce, int pos)
  91{
  92        while (pos < active_nr &&
  93               !strcmp(active_cache[pos]->name, ce->name)) {
  94                if (ce_stage(active_cache[pos]) == stage)
  95                        return 0;
  96                pos++;
  97        }
  98        return error("path '%s' does not have %s version",
  99                     ce->name,
 100                     (stage == 2) ? "our" : "their");
 101}
 102
 103static int check_all_stages(struct cache_entry *ce, int pos)
 104{
 105        if (ce_stage(ce) != 1 ||
 106            active_nr <= pos + 2 ||
 107            strcmp(active_cache[pos+1]->name, ce->name) ||
 108            ce_stage(active_cache[pos+1]) != 2 ||
 109            strcmp(active_cache[pos+2]->name, ce->name) ||
 110            ce_stage(active_cache[pos+2]) != 3)
 111                return error("path '%s' does not have all three versions",
 112                             ce->name);
 113        return 0;
 114}
 115
 116static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 117                          struct checkout *state)
 118{
 119        while (pos < active_nr &&
 120               !strcmp(active_cache[pos]->name, ce->name)) {
 121                if (ce_stage(active_cache[pos]) == stage)
 122                        return checkout_entry(active_cache[pos], state, NULL);
 123                pos++;
 124        }
 125        return error("path '%s' does not have %s version",
 126                     ce->name,
 127                     (stage == 2) ? "our" : "their");
 128}
 129
 130/* NEEDSWORK: share with merge-recursive */
 131static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 132{
 133        unsigned long size;
 134        enum object_type type;
 135
 136        if (!hashcmp(sha1, null_sha1)) {
 137                mm->ptr = xstrdup("");
 138                mm->size = 0;
 139                return;
 140        }
 141
 142        mm->ptr = read_sha1_file(sha1, &type, &size);
 143        if (!mm->ptr || type != OBJ_BLOB)
 144                die("unable to read blob object %s", sha1_to_hex(sha1));
 145        mm->size = size;
 146}
 147
 148static int checkout_merged(int pos, struct checkout *state)
 149{
 150        struct cache_entry *ce = active_cache[pos];
 151        const char *path = ce->name;
 152        mmfile_t ancestor, ours, theirs;
 153        int status;
 154        unsigned char sha1[20];
 155        mmbuffer_t result_buf;
 156
 157        if (ce_stage(ce) != 1 ||
 158            active_nr <= pos + 2 ||
 159            strcmp(active_cache[pos+1]->name, path) ||
 160            ce_stage(active_cache[pos+1]) != 2 ||
 161            strcmp(active_cache[pos+2]->name, path) ||
 162            ce_stage(active_cache[pos+2]) != 3)
 163                return error("path '%s' does not have all 3 versions", path);
 164
 165        fill_mm(active_cache[pos]->sha1, &ancestor);
 166        fill_mm(active_cache[pos+1]->sha1, &ours);
 167        fill_mm(active_cache[pos+2]->sha1, &theirs);
 168
 169        status = ll_merge(&result_buf, path, &ancestor,
 170                          &ours, "ours", &theirs, "theirs", 0);
 171        free(ancestor.ptr);
 172        free(ours.ptr);
 173        free(theirs.ptr);
 174        if (status < 0 || !result_buf.ptr) {
 175                free(result_buf.ptr);
 176                return error("path '%s': cannot merge", path);
 177        }
 178
 179        /*
 180         * NEEDSWORK:
 181         * There is absolutely no reason to write this as a blob object
 182         * and create a phony cache entry just to leak.  This hack is
 183         * primarily to get to the write_entry() machinery that massages
 184         * the contents to work-tree format and writes out which only
 185         * allows it for a cache entry.  The code in write_entry() needs
 186         * to be refactored to allow us to feed a <buffer, size, mode>
 187         * instead of a cache entry.  Such a refactoring would help
 188         * merge_recursive as well (it also writes the merge result to the
 189         * object database even when it may contain conflicts).
 190         */
 191        if (write_sha1_file(result_buf.ptr, result_buf.size,
 192                            blob_type, sha1))
 193                die("Unable to add merge result for '%s'", path);
 194        ce = make_cache_entry(create_ce_mode(active_cache[pos+1]->ce_mode),
 195                              sha1,
 196                              path, 2, 0);
 197        if (!ce)
 198                die("make_cache_entry failed for path '%s'", path);
 199        status = checkout_entry(ce, state, NULL);
 200        return status;
 201}
 202
 203static int checkout_paths(struct tree *source_tree, const char **pathspec,
 204                          struct checkout_opts *opts)
 205{
 206        int pos;
 207        struct checkout state;
 208        static char *ps_matched;
 209        unsigned char rev[20];
 210        int flag;
 211        struct commit *head;
 212        int errs = 0;
 213        int stage = opts->writeout_stage;
 214        int merge = opts->merge;
 215        int newfd;
 216        struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 217
 218        newfd = hold_locked_index(lock_file, 1);
 219        if (read_cache_preload(pathspec) < 0)
 220                return error("corrupt index file");
 221
 222        if (source_tree)
 223                read_tree_some(source_tree, pathspec);
 224
 225        for (pos = 0; pathspec[pos]; pos++)
 226                ;
 227        ps_matched = xcalloc(1, pos);
 228
 229        for (pos = 0; pos < active_nr; pos++) {
 230                struct cache_entry *ce = active_cache[pos];
 231                match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
 232        }
 233
 234        if (report_path_error(ps_matched, pathspec, 0))
 235                return 1;
 236
 237        /* Any unmerged paths? */
 238        for (pos = 0; pos < active_nr; pos++) {
 239                struct cache_entry *ce = active_cache[pos];
 240                if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 241                        if (!ce_stage(ce))
 242                                continue;
 243                        if (opts->force) {
 244                                warning("path '%s' is unmerged", ce->name);
 245                        } else if (stage) {
 246                                errs |= check_stage(stage, ce, pos);
 247                        } else if (opts->merge) {
 248                                errs |= check_all_stages(ce, pos);
 249                        } else {
 250                                errs = 1;
 251                                error("path '%s' is unmerged", ce->name);
 252                        }
 253                        pos = skip_same_name(ce, pos) - 1;
 254                }
 255        }
 256        if (errs)
 257                return 1;
 258
 259        /* Now we are committed to check them out */
 260        memset(&state, 0, sizeof(state));
 261        state.force = 1;
 262        state.refresh_cache = 1;
 263        for (pos = 0; pos < active_nr; pos++) {
 264                struct cache_entry *ce = active_cache[pos];
 265                if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 266                        if (!ce_stage(ce)) {
 267                                errs |= checkout_entry(ce, &state, NULL);
 268                                continue;
 269                        }
 270                        if (stage)
 271                                errs |= checkout_stage(stage, ce, pos, &state);
 272                        else if (merge)
 273                                errs |= checkout_merged(pos, &state);
 274                        pos = skip_same_name(ce, pos) - 1;
 275                }
 276        }
 277
 278        if (write_cache(newfd, active_cache, active_nr) ||
 279            commit_locked_index(lock_file))
 280                die("unable to write new index file");
 281
 282        resolve_ref("HEAD", rev, 0, &flag);
 283        head = lookup_commit_reference_gently(rev, 1);
 284
 285        errs |= post_checkout_hook(head, head, 0);
 286        return errs;
 287}
 288
 289static void show_local_changes(struct object *head)
 290{
 291        struct rev_info rev;
 292        /* I think we want full paths, even if we're in a subdirectory. */
 293        init_revisions(&rev, NULL);
 294        rev.abbrev = 0;
 295        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 296        if (diff_setup_done(&rev.diffopt) < 0)
 297                die("diff_setup_done failed");
 298        add_pending_object(&rev, head, NULL);
 299        run_diff_index(&rev, 0);
 300}
 301
 302static void describe_detached_head(char *msg, struct commit *commit)
 303{
 304        struct strbuf sb = STRBUF_INIT;
 305        struct pretty_print_context ctx = {0};
 306        parse_commit(commit);
 307        pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, &ctx);
 308        fprintf(stderr, "%s %s... %s\n", msg,
 309                find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 310        strbuf_release(&sb);
 311}
 312
 313static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
 314{
 315        struct unpack_trees_options opts;
 316        struct tree_desc tree_desc;
 317
 318        memset(&opts, 0, sizeof(opts));
 319        opts.head_idx = -1;
 320        opts.update = worktree;
 321        opts.skip_unmerged = !worktree;
 322        opts.reset = 1;
 323        opts.merge = 1;
 324        opts.fn = oneway_merge;
 325        opts.verbose_update = !o->quiet;
 326        opts.src_index = &the_index;
 327        opts.dst_index = &the_index;
 328        parse_tree(tree);
 329        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 330        switch (unpack_trees(1, &tree_desc, &opts)) {
 331        case -2:
 332                o->writeout_error = 1;
 333                /*
 334                 * We return 0 nevertheless, as the index is all right
 335                 * and more importantly we have made best efforts to
 336                 * update paths in the work tree, and we cannot revert
 337                 * them.
 338                 */
 339        case 0:
 340                return 0;
 341        default:
 342                return 128;
 343        }
 344}
 345
 346struct branch_info {
 347        const char *name; /* The short name used */
 348        const char *path; /* The full name of a real branch */
 349        struct commit *commit; /* The named commit */
 350};
 351
 352static void setup_branch_path(struct branch_info *branch)
 353{
 354        struct strbuf buf = STRBUF_INIT;
 355
 356        strbuf_branchname(&buf, branch->name);
 357        if (strcmp(buf.buf, branch->name))
 358                branch->name = xstrdup(buf.buf);
 359        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 360        branch->path = strbuf_detach(&buf, NULL);
 361}
 362
 363static int merge_working_tree(struct checkout_opts *opts,
 364                              struct branch_info *old, struct branch_info *new)
 365{
 366        int ret;
 367        struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 368        int newfd = hold_locked_index(lock_file, 1);
 369
 370        if (read_cache_preload(NULL) < 0)
 371                return error("corrupt index file");
 372
 373        if (opts->force) {
 374                ret = reset_tree(new->commit->tree, opts, 1);
 375                if (ret)
 376                        return ret;
 377        } else {
 378                struct tree_desc trees[2];
 379                struct tree *tree;
 380                struct unpack_trees_options topts;
 381
 382                memset(&topts, 0, sizeof(topts));
 383                topts.head_idx = -1;
 384                topts.src_index = &the_index;
 385                topts.dst_index = &the_index;
 386
 387                topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
 388
 389                refresh_cache(REFRESH_QUIET);
 390
 391                if (unmerged_cache()) {
 392                        error("you need to resolve your current index first");
 393                        return 1;
 394                }
 395
 396                /* 2-way merge to the new branch */
 397                topts.initial_checkout = is_cache_unborn();
 398                topts.update = 1;
 399                topts.merge = 1;
 400                topts.gently = opts->merge && old->commit;
 401                topts.verbose_update = !opts->quiet;
 402                topts.fn = twoway_merge;
 403                topts.dir = xcalloc(1, sizeof(*topts.dir));
 404                topts.dir->flags |= DIR_SHOW_IGNORED;
 405                topts.dir->exclude_per_dir = ".gitignore";
 406                tree = parse_tree_indirect(old->commit ?
 407                                           old->commit->object.sha1 :
 408                                           (unsigned char *)EMPTY_TREE_SHA1_BIN);
 409                init_tree_desc(&trees[0], tree->buffer, tree->size);
 410                tree = parse_tree_indirect(new->commit->object.sha1);
 411                init_tree_desc(&trees[1], tree->buffer, tree->size);
 412
 413                ret = unpack_trees(2, trees, &topts);
 414                if (ret == -1) {
 415                        /*
 416                         * Unpack couldn't do a trivial merge; either
 417                         * give up or do a real merge, depending on
 418                         * whether the merge flag was used.
 419                         */
 420                        struct tree *result;
 421                        struct tree *work;
 422                        struct merge_options o;
 423                        if (!opts->merge)
 424                                return 1;
 425
 426                        /*
 427                         * Without old->commit, the below is the same as
 428                         * the two-tree unpack we already tried and failed.
 429                         */
 430                        if (!old->commit)
 431                                return 1;
 432
 433                        /* Do more real merge */
 434
 435                        /*
 436                         * We update the index fully, then write the
 437                         * tree from the index, then merge the new
 438                         * branch with the current tree, with the old
 439                         * branch as the base. Then we reset the index
 440                         * (but not the working tree) to the new
 441                         * branch, leaving the working tree as the
 442                         * merged version, but skipping unmerged
 443                         * entries in the index.
 444                         */
 445
 446                        add_files_to_cache(NULL, NULL, 0);
 447                        init_merge_options(&o);
 448                        o.verbosity = 0;
 449                        work = write_tree_from_memory(&o);
 450
 451                        ret = reset_tree(new->commit->tree, opts, 1);
 452                        if (ret)
 453                                return ret;
 454                        o.branch1 = new->name;
 455                        o.branch2 = "local";
 456                        merge_trees(&o, new->commit->tree, work,
 457                                old->commit->tree, &result);
 458                        ret = reset_tree(new->commit->tree, opts, 0);
 459                        if (ret)
 460                                return ret;
 461                }
 462        }
 463
 464        if (write_cache(newfd, active_cache, active_nr) ||
 465            commit_locked_index(lock_file))
 466                die("unable to write new index file");
 467
 468        if (!opts->force && !opts->quiet)
 469                show_local_changes(&new->commit->object);
 470
 471        return 0;
 472}
 473
 474static void report_tracking(struct branch_info *new)
 475{
 476        struct strbuf sb = STRBUF_INIT;
 477        struct branch *branch = branch_get(new->name);
 478
 479        if (!format_tracking_info(branch, &sb))
 480                return;
 481        fputs(sb.buf, stdout);
 482        strbuf_release(&sb);
 483}
 484
 485static void update_refs_for_switch(struct checkout_opts *opts,
 486                                   struct branch_info *old,
 487                                   struct branch_info *new)
 488{
 489        struct strbuf msg = STRBUF_INIT;
 490        const char *old_desc;
 491        if (opts->new_branch) {
 492                create_branch(old->name, opts->new_branch, new->name, 0,
 493                              opts->new_branch_log, opts->track);
 494                new->name = opts->new_branch;
 495                setup_branch_path(new);
 496        }
 497
 498        old_desc = old->name;
 499        if (!old_desc && old->commit)
 500                old_desc = sha1_to_hex(old->commit->object.sha1);
 501        strbuf_addf(&msg, "checkout: moving from %s to %s",
 502                    old_desc ? old_desc : "(invalid)", new->name);
 503
 504        if (new->path) {
 505                create_symref("HEAD", new->path, msg.buf);
 506                if (!opts->quiet) {
 507                        if (old->path && !strcmp(new->path, old->path))
 508                                fprintf(stderr, "Already on '%s'\n",
 509                                        new->name);
 510                        else
 511                                fprintf(stderr, "Switched to%s branch '%s'\n",
 512                                        opts->new_branch ? " a new" : "",
 513                                        new->name);
 514                }
 515        } else if (strcmp(new->name, "HEAD")) {
 516                update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 517                           REF_NODEREF, DIE_ON_ERR);
 518                if (!opts->quiet) {
 519                        if (old->path)
 520                                fprintf(stderr, "Note: moving to '%s' which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n  git checkout -b <new_branch_name>\n", new->name);
 521                        describe_detached_head("HEAD is now at", new->commit);
 522                }
 523        }
 524        remove_branch_state();
 525        strbuf_release(&msg);
 526        if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
 527                report_tracking(new);
 528}
 529
 530static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 531{
 532        int ret = 0;
 533        struct branch_info old;
 534        unsigned char rev[20];
 535        int flag;
 536        memset(&old, 0, sizeof(old));
 537        old.path = resolve_ref("HEAD", rev, 0, &flag);
 538        old.commit = lookup_commit_reference_gently(rev, 1);
 539        if (!(flag & REF_ISSYMREF))
 540                old.path = NULL;
 541
 542        if (old.path && !prefixcmp(old.path, "refs/heads/"))
 543                old.name = old.path + strlen("refs/heads/");
 544
 545        if (!new->name) {
 546                new->name = "HEAD";
 547                new->commit = old.commit;
 548                if (!new->commit)
 549                        die("You are on a branch yet to be born");
 550                parse_commit(new->commit);
 551        }
 552
 553        ret = merge_working_tree(opts, &old, new);
 554        if (ret)
 555                return ret;
 556
 557        /*
 558         * If we were on a detached HEAD, but have now moved to
 559         * a new commit, we want to mention the old commit once more
 560         * to remind the user that it might be lost.
 561         */
 562        if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 563                describe_detached_head("Previous HEAD position was", old.commit);
 564
 565        update_refs_for_switch(opts, &old, new);
 566
 567        ret = post_checkout_hook(old.commit, new->commit, 1);
 568        return ret || opts->writeout_error;
 569}
 570
 571static int git_checkout_config(const char *var, const char *value, void *cb)
 572{
 573        return git_xmerge_config(var, value, cb);
 574}
 575
 576static int interactive_checkout(const char *revision, const char **pathspec,
 577                                struct checkout_opts *opts)
 578{
 579        return run_add_interactive(revision, "--patch=checkout", pathspec);
 580}
 581
 582struct tracking_name_data {
 583        const char *name;
 584        char *remote;
 585        int unique;
 586};
 587
 588static int check_tracking_name(const char *refname, const unsigned char *sha1,
 589                               int flags, void *cb_data)
 590{
 591        struct tracking_name_data *cb = cb_data;
 592        const char *slash;
 593
 594        if (prefixcmp(refname, "refs/remotes/"))
 595                return 0;
 596        slash = strchr(refname + 13, '/');
 597        if (!slash || strcmp(slash + 1, cb->name))
 598                return 0;
 599        if (cb->remote) {
 600                cb->unique = 0;
 601                return 0;
 602        }
 603        cb->remote = xstrdup(refname);
 604        return 0;
 605}
 606
 607static const char *unique_tracking_name(const char *name)
 608{
 609        struct tracking_name_data cb_data = { name, NULL, 1 };
 610        for_each_ref(check_tracking_name, &cb_data);
 611        if (cb_data.unique)
 612                return cb_data.remote;
 613        free(cb_data.remote);
 614        return NULL;
 615}
 616
 617int cmd_checkout(int argc, const char **argv, const char *prefix)
 618{
 619        struct checkout_opts opts;
 620        unsigned char rev[20];
 621        const char *arg;
 622        struct branch_info new;
 623        struct tree *source_tree = NULL;
 624        char *conflict_style = NULL;
 625        int patch_mode = 0;
 626        int dwim_new_local_branch = 1;
 627        struct option options[] = {
 628                OPT__QUIET(&opts.quiet),
 629                OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
 630                OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
 631                OPT_SET_INT('t', "track",  &opts.track, "track",
 632                        BRANCH_TRACK_EXPLICIT),
 633                OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
 634                            2),
 635                OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
 636                            3),
 637                OPT_BOOLEAN('f', "force", &opts.force, "force"),
 638                OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
 639                OPT_STRING(0, "conflict", &conflict_style, "style",
 640                           "conflict style (merge or diff3)"),
 641                OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
 642                { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
 643                  "second guess 'git checkout no-such-branch'",
 644                  PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
 645                OPT_END(),
 646        };
 647        int has_dash_dash;
 648
 649        memset(&opts, 0, sizeof(opts));
 650        memset(&new, 0, sizeof(new));
 651
 652        git_config(git_checkout_config, NULL);
 653
 654        opts.track = BRANCH_TRACK_UNSPECIFIED;
 655
 656        argc = parse_options(argc, argv, prefix, options, checkout_usage,
 657                             PARSE_OPT_KEEP_DASHDASH);
 658
 659        if (patch_mode && (opts.track > 0 || opts.new_branch
 660                           || opts.new_branch_log || opts.merge || opts.force))
 661                die ("--patch is incompatible with all other options");
 662
 663        /* --track without -b should DWIM */
 664        if (0 < opts.track && !opts.new_branch) {
 665                const char *argv0 = argv[0];
 666                if (!argc || !strcmp(argv0, "--"))
 667                        die ("--track needs a branch name");
 668                if (!prefixcmp(argv0, "refs/"))
 669                        argv0 += 5;
 670                if (!prefixcmp(argv0, "remotes/"))
 671                        argv0 += 8;
 672                argv0 = strchr(argv0, '/');
 673                if (!argv0 || !argv0[1])
 674                        die ("Missing branch name; try -b");
 675                opts.new_branch = argv0 + 1;
 676        }
 677
 678        if (conflict_style) {
 679                opts.merge = 1; /* implied */
 680                git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
 681        }
 682
 683        if (opts.force && opts.merge)
 684                die("git checkout: -f and -m are incompatible");
 685
 686        /*
 687         * case 1: git checkout <ref> -- [<paths>]
 688         *
 689         *   <ref> must be a valid tree, everything after the '--' must be
 690         *   a path.
 691         *
 692         * case 2: git checkout -- [<paths>]
 693         *
 694         *   everything after the '--' must be paths.
 695         *
 696         * case 3: git checkout <something> [<paths>]
 697         *
 698         *   With no paths, if <something> is a commit, that is to
 699         *   switch to the branch or detach HEAD at it.  As a special case,
 700         *   if <something> is A...B (missing A or B means HEAD but you can
 701         *   omit at most one side), and if there is a unique merge base
 702         *   between A and B, A...B names that merge base.
 703         *
 704         *   With no paths, if <something> is _not_ a commit, no -t nor -b
 705         *   was given, and there is a tracking branch whose name is
 706         *   <something> in one and only one remote, then this is a short-hand
 707         *   to fork local <something> from that remote tracking branch.
 708         *
 709         *   Otherwise <something> shall not be ambiguous.
 710         *   - If it's *only* a reference, treat it like case (1).
 711         *   - If it's only a path, treat it like case (2).
 712         *   - else: fail.
 713         *
 714         */
 715        if (argc) {
 716                if (!strcmp(argv[0], "--")) {       /* case (2) */
 717                        argv++;
 718                        argc--;
 719                        goto no_reference;
 720                }
 721
 722                arg = argv[0];
 723                has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 724
 725                if (!strcmp(arg, "-"))
 726                        arg = "@{-1}";
 727
 728                if (get_sha1_mb(arg, rev)) {
 729                        if (has_dash_dash)          /* case (1) */
 730                                die("invalid reference: %s", arg);
 731                        if (!patch_mode &&
 732                            dwim_new_local_branch &&
 733                            opts.track == BRANCH_TRACK_UNSPECIFIED &&
 734                            !opts.new_branch &&
 735                            !check_filename(NULL, arg) &&
 736                            argc == 1) {
 737                                const char *remote = unique_tracking_name(arg);
 738                                if (!remote || get_sha1(remote, rev))
 739                                        goto no_reference;
 740                                opts.new_branch = arg;
 741                                arg = remote;
 742                                /* DWIMmed to create local branch */
 743                        }
 744                        else
 745                                goto no_reference;
 746                }
 747
 748                /* we can't end up being in (2) anymore, eat the argument */
 749                argv++;
 750                argc--;
 751
 752                new.name = arg;
 753                if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
 754                        setup_branch_path(&new);
 755                        if (resolve_ref(new.path, rev, 1, NULL))
 756                                new.commit = lookup_commit_reference(rev);
 757                        else
 758                                new.path = NULL;
 759                        parse_commit(new.commit);
 760                        source_tree = new.commit->tree;
 761                } else
 762                        source_tree = parse_tree_indirect(rev);
 763
 764                if (!source_tree)                   /* case (1): want a tree */
 765                        die("reference is not a tree: %s", arg);
 766                if (!has_dash_dash) {/* case (3 -> 1) */
 767                        /*
 768                         * Do not complain the most common case
 769                         *      git checkout branch
 770                         * even if there happen to be a file called 'branch';
 771                         * it would be extremely annoying.
 772                         */
 773                        if (argc)
 774                                verify_non_filename(NULL, arg);
 775                }
 776                else {
 777                        argv++;
 778                        argc--;
 779                }
 780        }
 781
 782no_reference:
 783
 784        if (opts.track == BRANCH_TRACK_UNSPECIFIED)
 785                opts.track = git_branch_track;
 786
 787        if (argc) {
 788                const char **pathspec = get_pathspec(prefix, argv);
 789
 790                if (!pathspec)
 791                        die("invalid path specification");
 792
 793                if (patch_mode)
 794                        return interactive_checkout(new.name, pathspec, &opts);
 795
 796                /* Checkout paths */
 797                if (opts.new_branch) {
 798                        if (argc == 1) {
 799                                die("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
 800                        } else {
 801                                die("git checkout: updating paths is incompatible with switching branches.");
 802                        }
 803                }
 804
 805                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
 806                        die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
 807
 808                return checkout_paths(source_tree, pathspec, &opts);
 809        }
 810
 811        if (patch_mode)
 812                return interactive_checkout(new.name, NULL, &opts);
 813
 814        if (opts.new_branch) {
 815                struct strbuf buf = STRBUF_INIT;
 816                if (strbuf_check_branch_ref(&buf, opts.new_branch))
 817                        die("git checkout: we do not like '%s' as a branch name.",
 818                            opts.new_branch);
 819                if (!get_sha1(buf.buf, rev))
 820                        die("git checkout: branch %s already exists", opts.new_branch);
 821                strbuf_release(&buf);
 822        }
 823
 824        if (new.name && !new.commit) {
 825                die("Cannot switch branch to a non-commit.");
 826        }
 827        if (opts.writeout_stage)
 828                die("--ours/--theirs is incompatible with switching branches.");
 829
 830        return switch_branches(&opts, &new);
 831}