e817956d96fe50bce975a1c87fd8f8df132e53ea
   1/*
   2 * "git rebase" builtin command
   3 *
   4 * Copyright (c) 2018 Pratik Karki
   5 */
   6
   7#include "builtin.h"
   8#include "run-command.h"
   9#include "exec-cmd.h"
  10#include "argv-array.h"
  11#include "dir.h"
  12#include "packfile.h"
  13#include "refs.h"
  14#include "quote.h"
  15#include "config.h"
  16#include "cache-tree.h"
  17#include "unpack-trees.h"
  18#include "lockfile.h"
  19#include "parse-options.h"
  20#include "commit.h"
  21#include "diff.h"
  22#include "wt-status.h"
  23#include "revision.h"
  24
  25static char const * const builtin_rebase_usage[] = {
  26        N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
  27                "[<upstream>] [<branch>]"),
  28        N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
  29                "--root [<branch>]"),
  30        N_("git rebase --continue | --abort | --skip | --edit-todo"),
  31        NULL
  32};
  33
  34static GIT_PATH_FUNC(apply_dir, "rebase-apply")
  35static GIT_PATH_FUNC(merge_dir, "rebase-merge")
  36
  37enum rebase_type {
  38        REBASE_UNSPECIFIED = -1,
  39        REBASE_AM,
  40        REBASE_MERGE,
  41        REBASE_INTERACTIVE,
  42        REBASE_PRESERVE_MERGES
  43};
  44
  45static int use_builtin_rebase(void)
  46{
  47        struct child_process cp = CHILD_PROCESS_INIT;
  48        struct strbuf out = STRBUF_INIT;
  49        int ret;
  50
  51        argv_array_pushl(&cp.args,
  52                         "config", "--bool", "rebase.usebuiltin", NULL);
  53        cp.git_cmd = 1;
  54        if (capture_command(&cp, &out, 6)) {
  55                strbuf_release(&out);
  56                return 0;
  57        }
  58
  59        strbuf_trim(&out);
  60        ret = !strcmp("true", out.buf);
  61        strbuf_release(&out);
  62        return ret;
  63}
  64
  65static int apply_autostash(void)
  66{
  67        warning("TODO");
  68        return 0;
  69}
  70
  71struct rebase_options {
  72        enum rebase_type type;
  73        const char *state_dir;
  74        struct commit *upstream;
  75        const char *upstream_name;
  76        const char *upstream_arg;
  77        char *head_name;
  78        struct object_id orig_head;
  79        struct commit *onto;
  80        const char *onto_name;
  81        const char *revisions;
  82        const char *switch_to;
  83        int root;
  84        struct commit *restrict_revision;
  85        int dont_finish_rebase;
  86        enum {
  87                REBASE_NO_QUIET = 1<<0,
  88                REBASE_VERBOSE = 1<<1,
  89                REBASE_DIFFSTAT = 1<<2,
  90                REBASE_FORCE = 1<<3,
  91                REBASE_INTERACTIVE_EXPLICIT = 1<<4,
  92        } flags;
  93        struct strbuf git_am_opt;
  94};
  95
  96static int is_interactive(struct rebase_options *opts)
  97{
  98        return opts->type == REBASE_INTERACTIVE ||
  99                opts->type == REBASE_PRESERVE_MERGES;
 100}
 101
 102/* Returns the filename prefixed by the state_dir */
 103static const char *state_dir_path(const char *filename, struct rebase_options *opts)
 104{
 105        static struct strbuf path = STRBUF_INIT;
 106        static size_t prefix_len;
 107
 108        if (!prefix_len) {
 109                strbuf_addf(&path, "%s/", opts->state_dir);
 110                prefix_len = path.len;
 111        }
 112
 113        strbuf_setlen(&path, prefix_len);
 114        strbuf_addstr(&path, filename);
 115        return path.buf;
 116}
 117
 118static int finish_rebase(struct rebase_options *opts)
 119{
 120        struct strbuf dir = STRBUF_INIT;
 121        const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 122
 123        delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 124        apply_autostash();
 125        close_all_packs(the_repository->objects);
 126        /*
 127         * We ignore errors in 'gc --auto', since the
 128         * user should see them.
 129         */
 130        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 131        strbuf_addstr(&dir, opts->state_dir);
 132        remove_dir_recursively(&dir, 0);
 133        strbuf_release(&dir);
 134
 135        return 0;
 136}
 137
 138static struct commit *peel_committish(const char *name)
 139{
 140        struct object *obj;
 141        struct object_id oid;
 142
 143        if (get_oid(name, &oid))
 144                return NULL;
 145        obj = parse_object(the_repository, &oid);
 146        return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
 147}
 148
 149static void add_var(struct strbuf *buf, const char *name, const char *value)
 150{
 151        if (!value)
 152                strbuf_addf(buf, "unset %s; ", name);
 153        else {
 154                strbuf_addf(buf, "%s=", name);
 155                sq_quote_buf(buf, value);
 156                strbuf_addstr(buf, "; ");
 157        }
 158}
 159
 160static int run_specific_rebase(struct rebase_options *opts)
 161{
 162        const char *argv[] = { NULL, NULL };
 163        struct strbuf script_snippet = STRBUF_INIT;
 164        int status;
 165        const char *backend, *backend_func;
 166
 167        add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
 168        add_var(&script_snippet, "state_dir", opts->state_dir);
 169
 170        add_var(&script_snippet, "upstream_name", opts->upstream_name);
 171        add_var(&script_snippet, "upstream",
 172                                 oid_to_hex(&opts->upstream->object.oid));
 173        add_var(&script_snippet, "head_name",
 174                opts->head_name ? opts->head_name : "detached HEAD");
 175        add_var(&script_snippet, "orig_head", oid_to_hex(&opts->orig_head));
 176        add_var(&script_snippet, "onto", oid_to_hex(&opts->onto->object.oid));
 177        add_var(&script_snippet, "onto_name", opts->onto_name);
 178        add_var(&script_snippet, "revisions", opts->revisions);
 179        add_var(&script_snippet, "restrict_revision", opts->restrict_revision ?
 180                oid_to_hex(&opts->restrict_revision->object.oid) : NULL);
 181        add_var(&script_snippet, "GIT_QUIET",
 182                opts->flags & REBASE_NO_QUIET ? "" : "t");
 183        add_var(&script_snippet, "git_am_opt", opts->git_am_opt.buf);
 184        add_var(&script_snippet, "verbose",
 185                opts->flags & REBASE_VERBOSE ? "t" : "");
 186        add_var(&script_snippet, "diffstat",
 187                opts->flags & REBASE_DIFFSTAT ? "t" : "");
 188        add_var(&script_snippet, "force_rebase",
 189                opts->flags & REBASE_FORCE ? "t" : "");
 190        if (opts->switch_to)
 191                add_var(&script_snippet, "switch_to", opts->switch_to);
 192
 193        switch (opts->type) {
 194        case REBASE_AM:
 195                backend = "git-rebase--am";
 196                backend_func = "git_rebase__am";
 197                break;
 198        case REBASE_INTERACTIVE:
 199                backend = "git-rebase--interactive";
 200                backend_func = "git_rebase__interactive";
 201                break;
 202        case REBASE_MERGE:
 203                backend = "git-rebase--merge";
 204                backend_func = "git_rebase__merge";
 205                break;
 206        case REBASE_PRESERVE_MERGES:
 207                backend = "git-rebase--preserve-merges";
 208                backend_func = "git_rebase__preserve_merges";
 209                break;
 210        default:
 211                BUG("Unhandled rebase type %d", opts->type);
 212                break;
 213        }
 214
 215        strbuf_addf(&script_snippet,
 216                    ". git-sh-setup && . git-rebase--common &&"
 217                    " . %s && %s", backend, backend_func);
 218        argv[0] = script_snippet.buf;
 219
 220        status = run_command_v_opt(argv, RUN_USING_SHELL);
 221        if (opts->dont_finish_rebase)
 222                ; /* do nothing */
 223        else if (status == 0) {
 224                if (!file_exists(state_dir_path("stopped-sha", opts)))
 225                        finish_rebase(opts);
 226        } else if (status == 2) {
 227                struct strbuf dir = STRBUF_INIT;
 228
 229                apply_autostash();
 230                strbuf_addstr(&dir, opts->state_dir);
 231                remove_dir_recursively(&dir, 0);
 232                strbuf_release(&dir);
 233                die("Nothing to do");
 234        }
 235
 236        strbuf_release(&script_snippet);
 237
 238        return status ? -1 : 0;
 239}
 240
 241#define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
 242
 243static int reset_head(struct object_id *oid, const char *action,
 244                      const char *switch_to_branch, int detach_head)
 245{
 246        struct object_id head_oid;
 247        struct tree_desc desc;
 248        struct lock_file lock = LOCK_INIT;
 249        struct unpack_trees_options unpack_tree_opts;
 250        struct tree *tree;
 251        const char *reflog_action;
 252        struct strbuf msg = STRBUF_INIT;
 253        size_t prefix_len;
 254        struct object_id *orig = NULL, oid_orig,
 255                *old_orig = NULL, oid_old_orig;
 256        int ret = 0;
 257
 258        if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
 259                BUG("Not a fully qualified branch: '%s'", switch_to_branch);
 260
 261        if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
 262                return -1;
 263
 264        if (!oid) {
 265                if (get_oid("HEAD", &head_oid)) {
 266                        rollback_lock_file(&lock);
 267                        return error(_("could not determine HEAD revision"));
 268                }
 269                oid = &head_oid;
 270        }
 271
 272        memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
 273        setup_unpack_trees_porcelain(&unpack_tree_opts, action);
 274        unpack_tree_opts.head_idx = 1;
 275        unpack_tree_opts.src_index = the_repository->index;
 276        unpack_tree_opts.dst_index = the_repository->index;
 277        unpack_tree_opts.fn = oneway_merge;
 278        unpack_tree_opts.update = 1;
 279        unpack_tree_opts.merge = 1;
 280        if (!detach_head)
 281                unpack_tree_opts.reset = 1;
 282
 283        if (read_index_unmerged(the_repository->index) < 0) {
 284                rollback_lock_file(&lock);
 285                return error(_("could not read index"));
 286        }
 287
 288        if (!fill_tree_descriptor(&desc, oid)) {
 289                error(_("failed to find tree of %s"), oid_to_hex(oid));
 290                rollback_lock_file(&lock);
 291                free((void *)desc.buffer);
 292                return -1;
 293        }
 294
 295        if (unpack_trees(1, &desc, &unpack_tree_opts)) {
 296                rollback_lock_file(&lock);
 297                free((void *)desc.buffer);
 298                return -1;
 299        }
 300
 301        tree = parse_tree_indirect(oid);
 302        prime_cache_tree(the_repository->index, tree);
 303
 304        if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0)
 305                ret = error(_("could not write index"));
 306        free((void *)desc.buffer);
 307
 308        if (ret)
 309                return ret;
 310
 311        reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
 312        strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
 313        prefix_len = msg.len;
 314
 315        if (!get_oid("ORIG_HEAD", &oid_old_orig))
 316                old_orig = &oid_old_orig;
 317        if (!get_oid("HEAD", &oid_orig)) {
 318                orig = &oid_orig;
 319                strbuf_addstr(&msg, "updating ORIG_HEAD");
 320                update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
 321                           UPDATE_REFS_MSG_ON_ERR);
 322        } else if (old_orig)
 323                delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
 324        strbuf_setlen(&msg, prefix_len);
 325        strbuf_addstr(&msg, "updating HEAD");
 326        if (!switch_to_branch)
 327                ret = update_ref(msg.buf, "HEAD", oid, orig, REF_NO_DEREF,
 328                                 UPDATE_REFS_MSG_ON_ERR);
 329        else {
 330                ret = create_symref("HEAD", switch_to_branch, msg.buf);
 331                if (!ret)
 332                        ret = update_ref(msg.buf, "HEAD", oid, NULL, 0,
 333                                         UPDATE_REFS_MSG_ON_ERR);
 334        }
 335
 336        strbuf_release(&msg);
 337        return ret;
 338}
 339
 340static int rebase_config(const char *var, const char *value, void *data)
 341{
 342        struct rebase_options *opts = data;
 343
 344        if (!strcmp(var, "rebase.stat")) {
 345                if (git_config_bool(var, value))
 346                        opts->flags |= REBASE_DIFFSTAT;
 347                else
 348                        opts->flags &= !REBASE_DIFFSTAT;
 349                return 0;
 350        }
 351
 352        return git_default_config(var, value, data);
 353}
 354
 355/*
 356 * Determines whether the commits in from..to are linear, i.e. contain
 357 * no merge commits. This function *expects* `from` to be an ancestor of
 358 * `to`.
 359 */
 360static int is_linear_history(struct commit *from, struct commit *to)
 361{
 362        while (to && to != from) {
 363                parse_commit(to);
 364                if (!to->parents)
 365                        return 1;
 366                if (to->parents->next)
 367                        return 0;
 368                to = to->parents->item;
 369        }
 370        return 1;
 371}
 372
 373static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
 374                            struct object_id *merge_base)
 375{
 376        struct commit *head = lookup_commit(the_repository, head_oid);
 377        struct commit_list *merge_bases;
 378        int res;
 379
 380        if (!head)
 381                return 0;
 382
 383        merge_bases = get_merge_bases(onto, head);
 384        if (merge_bases && !merge_bases->next) {
 385                oidcpy(merge_base, &merge_bases->item->object.oid);
 386                res = !oidcmp(merge_base, &onto->object.oid);
 387        } else {
 388                oidcpy(merge_base, &null_oid);
 389                res = 0;
 390        }
 391        free_commit_list(merge_bases);
 392        return res && is_linear_history(onto, head);
 393}
 394
 395int cmd_rebase(int argc, const char **argv, const char *prefix)
 396{
 397        struct rebase_options options = {
 398                .type = REBASE_UNSPECIFIED,
 399                .flags = REBASE_NO_QUIET,
 400                .git_am_opt = STRBUF_INIT,
 401        };
 402        const char *branch_name;
 403        int ret, flags, in_progress = 0;
 404        int ok_to_skip_pre_rebase = 0;
 405        struct strbuf msg = STRBUF_INIT;
 406        struct strbuf revisions = STRBUF_INIT;
 407        struct strbuf buf = STRBUF_INIT;
 408        struct object_id merge_base;
 409        struct option builtin_rebase_options[] = {
 410                OPT_STRING(0, "onto", &options.onto_name,
 411                           N_("revision"),
 412                           N_("rebase onto given branch instead of upstream")),
 413                OPT_BOOL(0, "no-verify", &ok_to_skip_pre_rebase,
 414                         N_("allow pre-rebase hook to run")),
 415                OPT_NEGBIT('q', "quiet", &options.flags,
 416                           N_("be quiet. implies --no-stat"),
 417                           REBASE_NO_QUIET| REBASE_VERBOSE | REBASE_DIFFSTAT),
 418                OPT_BIT('v', "verbose", &options.flags,
 419                        N_("display a diffstat of what changed upstream"),
 420                        REBASE_NO_QUIET | REBASE_VERBOSE | REBASE_DIFFSTAT),
 421                {OPTION_NEGBIT, 'n', "no-stat", &options.flags, NULL,
 422                        N_("do not show diffstat of what changed upstream"),
 423                        PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
 424                OPT_BIT('f', "force-rebase", &options.flags,
 425                        N_("cherry-pick all commits, even if unchanged"),
 426                        REBASE_FORCE),
 427                OPT_BIT(0, "no-ff", &options.flags,
 428                        N_("cherry-pick all commits, even if unchanged"),
 429                        REBASE_FORCE),
 430                OPT_END(),
 431        };
 432
 433        /*
 434         * NEEDSWORK: Once the builtin rebase has been tested enough
 435         * and git-legacy-rebase.sh is retired to contrib/, this preamble
 436         * can be removed.
 437         */
 438
 439        if (!use_builtin_rebase()) {
 440                const char *path = mkpath("%s/git-legacy-rebase",
 441                                          git_exec_path());
 442
 443                if (sane_execvp(path, (char **)argv) < 0)
 444                        die_errno(_("could not exec %s"), path);
 445                else
 446                        BUG("sane_execvp() returned???");
 447        }
 448
 449        if (argc == 2 && !strcmp(argv[1], "-h"))
 450                usage_with_options(builtin_rebase_usage,
 451                                   builtin_rebase_options);
 452
 453        prefix = setup_git_directory();
 454        trace_repo_setup(prefix);
 455        setup_work_tree();
 456
 457        git_config(rebase_config, &options);
 458
 459        if (is_directory(apply_dir())) {
 460                options.type = REBASE_AM;
 461                options.state_dir = apply_dir();
 462        } else if (is_directory(merge_dir())) {
 463                strbuf_reset(&buf);
 464                strbuf_addf(&buf, "%s/rewritten", merge_dir());
 465                if (is_directory(buf.buf)) {
 466                        options.type = REBASE_PRESERVE_MERGES;
 467                        options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 468                } else {
 469                        strbuf_reset(&buf);
 470                        strbuf_addf(&buf, "%s/interactive", merge_dir());
 471                        if(file_exists(buf.buf)) {
 472                                options.type = REBASE_INTERACTIVE;
 473                                options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 474                        } else
 475                                options.type = REBASE_MERGE;
 476                }
 477                options.state_dir = merge_dir();
 478        }
 479
 480        if (options.type != REBASE_UNSPECIFIED)
 481                in_progress = 1;
 482
 483        argc = parse_options(argc, argv, prefix,
 484                             builtin_rebase_options,
 485                             builtin_rebase_usage, 0);
 486
 487        if (argc > 2)
 488                usage_with_options(builtin_rebase_usage,
 489                                   builtin_rebase_options);
 490
 491        /* Make sure no rebase is in progress */
 492        if (in_progress) {
 493                const char *last_slash = strrchr(options.state_dir, '/');
 494                const char *state_dir_base =
 495                        last_slash ? last_slash + 1 : options.state_dir;
 496                const char *cmd_live_rebase =
 497                        "git rebase (--continue | --abort | --skip)";
 498                strbuf_reset(&buf);
 499                strbuf_addf(&buf, "rm -fr \"%s\"", options.state_dir);
 500                die(_("It seems that there is already a %s directory, and\n"
 501                      "I wonder if you are in the middle of another rebase.  "
 502                      "If that is the\n"
 503                      "case, please try\n\t%s\n"
 504                      "If that is not the case, please\n\t%s\n"
 505                      "and run me again.  I am stopping in case you still "
 506                      "have something\n"
 507                      "valuable there.\n"),
 508                    state_dir_base, cmd_live_rebase, buf.buf);
 509        }
 510
 511        if (!(options.flags & REBASE_NO_QUIET))
 512                strbuf_addstr(&options.git_am_opt, " -q");
 513
 514        switch (options.type) {
 515        case REBASE_MERGE:
 516        case REBASE_INTERACTIVE:
 517        case REBASE_PRESERVE_MERGES:
 518                options.state_dir = merge_dir();
 519                break;
 520        case REBASE_AM:
 521                options.state_dir = apply_dir();
 522                break;
 523        default:
 524                /* the default rebase backend is `--am` */
 525                options.type = REBASE_AM;
 526                options.state_dir = apply_dir();
 527                break;
 528        }
 529
 530        if (!options.root) {
 531                if (argc < 1)
 532                        die("TODO: handle @{upstream}");
 533                else {
 534                        options.upstream_name = argv[0];
 535                        argc--;
 536                        argv++;
 537                        if (!strcmp(options.upstream_name, "-"))
 538                                options.upstream_name = "@{-1}";
 539                }
 540                options.upstream = peel_committish(options.upstream_name);
 541                if (!options.upstream)
 542                        die(_("invalid upstream '%s'"), options.upstream_name);
 543                options.upstream_arg = options.upstream_name;
 544        } else
 545                die("TODO: upstream for --root");
 546
 547        /* Make sure the branch to rebase onto is valid. */
 548        if (!options.onto_name)
 549                options.onto_name = options.upstream_name;
 550        if (strstr(options.onto_name, "...")) {
 551                if (get_oid_mb(options.onto_name, &merge_base) < 0)
 552                        die(_("'%s': need exactly one merge base"),
 553                            options.onto_name);
 554                options.onto = lookup_commit_or_die(&merge_base,
 555                                                    options.onto_name);
 556        } else {
 557                options.onto = peel_committish(options.onto_name);
 558                if (!options.onto)
 559                        die(_("Does not point to a valid commit '%s'"),
 560                                options.onto_name);
 561        }
 562
 563        /*
 564         * If the branch to rebase is given, that is the branch we will rebase
 565         * branch_name -- branch/commit being rebased, or
 566         *                HEAD (already detached)
 567         * orig_head -- commit object name of tip of the branch before rebasing
 568         * head_name -- refs/heads/<that-branch> or NULL (detached HEAD)
 569         */
 570        if (argc == 1) {
 571                /* Is it "rebase other branchname" or "rebase other commit"? */
 572                branch_name = argv[0];
 573                options.switch_to = argv[0];
 574
 575                /* Is it a local branch? */
 576                strbuf_reset(&buf);
 577                strbuf_addf(&buf, "refs/heads/%s", branch_name);
 578                if (!read_ref(buf.buf, &options.orig_head))
 579                        options.head_name = xstrdup(buf.buf);
 580                /* If not is it a valid ref (branch or commit)? */
 581                else if (!get_oid(branch_name, &options.orig_head))
 582                        options.head_name = NULL;
 583                else
 584                        die(_("fatal: no such branch/commit '%s'"),
 585                            branch_name);
 586        } else if (argc == 0) {
 587                /* Do not need to switch branches, we are already on it. */
 588                options.head_name =
 589                        xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
 590                                         &flags));
 591                if (!options.head_name)
 592                        die(_("No such ref: %s"), "HEAD");
 593                if (flags & REF_ISSYMREF) {
 594                        if (!skip_prefix(options.head_name,
 595                                         "refs/heads/", &branch_name))
 596                                branch_name = options.head_name;
 597
 598                } else {
 599                        free(options.head_name);
 600                        options.head_name = NULL;
 601                        branch_name = "HEAD";
 602                }
 603                if (get_oid("HEAD", &options.orig_head))
 604                        die(_("Could not resolve HEAD to a revision"));
 605        } else
 606                BUG("unexpected number of arguments left to parse");
 607
 608        if (read_index(the_repository->index) < 0)
 609                die(_("could not read index"));
 610
 611        if (require_clean_work_tree("rebase",
 612                                    _("Please commit or stash them."), 1, 1)) {
 613                ret = 1;
 614                goto cleanup;
 615        }
 616
 617        /*
 618         * Now we are rebasing commits upstream..orig_head (or with --root,
 619         * everything leading up to orig_head) on top of onto.
 620         */
 621
 622        /*
 623         * Check if we are already based on onto with linear history,
 624         * but this should be done only when upstream and onto are the same
 625         * and if this is not an interactive rebase.
 626         */
 627        if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
 628            !is_interactive(&options) && !options.restrict_revision &&
 629            !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
 630                int flag;
 631
 632                if (!(options.flags & REBASE_FORCE)) {
 633                        /* Lazily switch to the target branch if needed... */
 634                        if (options.switch_to) {
 635                                struct object_id oid;
 636
 637                                if (get_oid(options.switch_to, &oid) < 0) {
 638                                        ret = !!error(_("could not parse '%s'"),
 639                                                      options.switch_to);
 640                                        goto cleanup;
 641                                }
 642
 643                                strbuf_reset(&buf);
 644                                strbuf_addf(&buf, "rebase: checkout %s",
 645                                            options.switch_to);
 646                                if (reset_head(&oid, "checkout",
 647                                               options.head_name, 0) < 0) {
 648                                        ret = !!error(_("could not switch to "
 649                                                        "%s"),
 650                                                      options.switch_to);
 651                                        goto cleanup;
 652                                }
 653                        }
 654
 655                        if (!(options.flags & REBASE_NO_QUIET))
 656                                ; /* be quiet */
 657                        else if (!strcmp(branch_name, "HEAD") &&
 658                                 resolve_ref_unsafe("HEAD", 0, NULL, &flag))
 659                                puts(_("HEAD is up to date."));
 660                        else
 661                                printf(_("Current branch %s is up to date.\n"),
 662                                       branch_name);
 663                        ret = !!finish_rebase(&options);
 664                        goto cleanup;
 665                } else if (!(options.flags & REBASE_NO_QUIET))
 666                        ; /* be quiet */
 667                else if (!strcmp(branch_name, "HEAD") &&
 668                         resolve_ref_unsafe("HEAD", 0, NULL, &flag))
 669                        puts(_("HEAD is up to date, rebase forced."));
 670                else
 671                        printf(_("Current branch %s is up to date, rebase "
 672                                 "forced.\n"), branch_name);
 673        }
 674
 675        /* If a hook exists, give it a chance to interrupt*/
 676        if (!ok_to_skip_pre_rebase &&
 677            run_hook_le(NULL, "pre-rebase", options.upstream_arg,
 678                        argc ? argv[0] : NULL, NULL))
 679                die(_("The pre-rebase hook refused to rebase."));
 680
 681        if (options.flags & REBASE_DIFFSTAT) {
 682                struct diff_options opts;
 683
 684                if (options.flags & REBASE_VERBOSE)
 685                        printf(_("Changes from %s to %s:\n"),
 686                                oid_to_hex(&merge_base),
 687                                oid_to_hex(&options.onto->object.oid));
 688
 689                /* We want color (if set), but no pager */
 690                diff_setup(&opts);
 691                opts.stat_width = -1; /* use full terminal width */
 692                opts.stat_graph_width = -1; /* respect statGraphWidth config */
 693                opts.output_format |=
 694                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 695                opts.detect_rename = DIFF_DETECT_RENAME;
 696                diff_setup_done(&opts);
 697                diff_tree_oid(&merge_base, &options.onto->object.oid,
 698                              "", &opts);
 699                diffcore_std(&opts);
 700                diff_flush(&opts);
 701        }
 702
 703        /* Detach HEAD and reset the tree */
 704        if (options.flags & REBASE_NO_QUIET)
 705                printf(_("First, rewinding head to replay your work on top of "
 706                         "it...\n"));
 707
 708        strbuf_addf(&msg, "rebase: checkout %s", options.onto_name);
 709        if (reset_head(&options.onto->object.oid, "checkout", NULL, 1))
 710                die(_("Could not detach HEAD"));
 711        strbuf_release(&msg);
 712
 713        strbuf_addf(&revisions, "%s..%s",
 714                    options.root ? oid_to_hex(&options.onto->object.oid) :
 715                    (options.restrict_revision ?
 716                     oid_to_hex(&options.restrict_revision->object.oid) :
 717                     oid_to_hex(&options.upstream->object.oid)),
 718                    oid_to_hex(&options.orig_head));
 719
 720        options.revisions = revisions.buf;
 721
 722        ret = !!run_specific_rebase(&options);
 723
 724cleanup:
 725        strbuf_release(&revisions);
 726        free(options.head_name);
 727        return ret;
 728}