builtin/rebase.c

   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
  25 static 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
  34 static GIT_PATH_FUNC(apply_dir, "rebase-apply")
  35 static GIT_PATH_FUNC(merge_dir, "rebase-merge")
  36
  37 enum rebase_type {
  38         REBASE_UNSPECIFIED = -1,
  39         REBASE_AM,
  40         REBASE_MERGE,
  41         REBASE_INTERACTIVE,
  42         REBASE_PRESERVE_MERGES
  43 };
  44
  45 static 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
  65 static int apply_autostash(void)
  66 {
  67         warning("TODO");
  68         return 0;
  69 }
  70
  71 struct 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         const char *action;
  95 };
  96
  97 static int is_interactive(struct rebase_options *opts)
  98 {
  99         return opts->type == REBASE_INTERACTIVE ||
 100                 opts->type == REBASE_PRESERVE_MERGES;
 101 }
 102
 103 /* Returns the filename prefixed by the state_dir */
 104 static const char *state_dir_path(const char *filename, struct rebase_options *opts)
 105 {
 106         static struct strbuf path = STRBUF_INIT;
 107         static size_t prefix_len;
 108
 109         if (!prefix_len) {
 110                 strbuf_addf(&path, "%s/", opts->state_dir);
 111                 prefix_len = path.len;
 112         }
 113
 114         strbuf_setlen(&path, prefix_len);
 115         strbuf_addstr(&path, filename);
 116         return path.buf;
 117 }
 118
 119 /* Read one file, then strip line endings */
 120 static int read_one(const char *path, struct strbuf *buf)
 121 {
 122         if (strbuf_read_file(buf, path, 0) < 0)
 123                 return error_errno(_("could not read '%s'"), path);
 124         strbuf_trim_trailing_newline(buf);
 125         return 0;
 126 }
 127
 128 /* Initialize the rebase options from the state directory. */
 129 static int read_basic_state(struct rebase_options *opts)
 130 {
 131         struct strbuf head_name = STRBUF_INIT;
 132         struct strbuf buf = STRBUF_INIT;
 133         struct object_id oid;
 134
 135         if (read_one(state_dir_path("head-name", opts), &head_name) ||
 136             read_one(state_dir_path("onto", opts), &buf))
 137                 return -1;
 138         opts->head_name = starts_with(head_name.buf, "refs/") ?
 139                 xstrdup(head_name.buf) : NULL;
 140         strbuf_release(&head_name);
 141         if (get_oid(buf.buf, &oid))
 142                 return error(_("could not get 'onto': '%s'"), buf.buf);
 143         opts->onto = lookup_commit_or_die(&oid, buf.buf);
 144
 145         /*
 146          * We always write to orig-head, but interactive rebase used to write to
 147          * head. Fall back to reading from head to cover for the case that the
 148          * user upgraded git with an ongoing interactive rebase.
 149          */
 150         strbuf_reset(&buf);
 151         if (file_exists(state_dir_path("orig-head", opts))) {
 152                 if (read_one(state_dir_path("orig-head", opts), &buf))
 153                         return -1;
 154         } else if (read_one(state_dir_path("head", opts), &buf))
 155                 return -1;
 156         if (get_oid(buf.buf, &opts->orig_head))
 157                 return error(_("invalid orig-head: '%s'"), buf.buf);
 158
 159         strbuf_reset(&buf);
 160         if (read_one(state_dir_path("quiet", opts), &buf))
 161                 return -1;
 162         if (buf.len)
 163                 opts->flags &= ~REBASE_NO_QUIET;
 164         else
 165                 opts->flags |= REBASE_NO_QUIET;
 166
 167         if (file_exists(state_dir_path("verbose", opts)))
 168                 opts->flags |= REBASE_VERBOSE;
 169
 170         strbuf_release(&buf);
 171
 172         return 0;
 173 }
 174
 175 static int finish_rebase(struct rebase_options *opts)
 176 {
 177         struct strbuf dir = STRBUF_INIT;
 178         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 179
 180         delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 181         apply_autostash();
 182         close_all_packs(the_repository->objects);
 183         /*
 184          * We ignore errors in 'gc --auto', since the
 185          * user should see them.
 186          */
 187         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 188         strbuf_addstr(&dir, opts->state_dir);
 189         remove_dir_recursively(&dir, 0);
 190         strbuf_release(&dir);
 191
 192         return 0;
 193 }
 194
 195 static struct commit *peel_committish(const char *name)
 196 {
 197         struct object *obj;
 198         struct object_id oid;
 199
 200         if (get_oid(name, &oid))
 201                 return NULL;
 202         obj = parse_object(the_repository, &oid);
 203         return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
 204 }
 205
 206 static void add_var(struct strbuf *buf, const char *name, const char *value)
 207 {
 208         if (!value)
 209                 strbuf_addf(buf, "unset %s; ", name);
 210         else {
 211                 strbuf_addf(buf, "%s=", name);
 212                 sq_quote_buf(buf, value);
 213                 strbuf_addstr(buf, "; ");
 214         }
 215 }
 216
 217 static int run_specific_rebase(struct rebase_options *opts)
 218 {
 219         const char *argv[] = { NULL, NULL };
 220         struct strbuf script_snippet = STRBUF_INIT;
 221         int status;
 222         const char *backend, *backend_func;
 223
 224         add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
 225         add_var(&script_snippet, "state_dir", opts->state_dir);
 226
 227         add_var(&script_snippet, "upstream_name", opts->upstream_name);
 228         add_var(&script_snippet, "upstream", opts->upstream ?
 229                 oid_to_hex(&opts->upstream->object.oid) : NULL);
 230         add_var(&script_snippet, "head_name",
 231                 opts->head_name ? opts->head_name : "detached HEAD");
 232         add_var(&script_snippet, "orig_head", oid_to_hex(&opts->orig_head));
 233         add_var(&script_snippet, "onto", opts->onto ?
 234                 oid_to_hex(&opts->onto->object.oid) : NULL);
 235         add_var(&script_snippet, "onto_name", opts->onto_name);
 236         add_var(&script_snippet, "revisions", opts->revisions);
 237         add_var(&script_snippet, "restrict_revision", opts->restrict_revision ?
 238                 oid_to_hex(&opts->restrict_revision->object.oid) : NULL);
 239         add_var(&script_snippet, "GIT_QUIET",
 240                 opts->flags & REBASE_NO_QUIET ? "" : "t");
 241         add_var(&script_snippet, "git_am_opt", opts->git_am_opt.buf);
 242         add_var(&script_snippet, "verbose",
 243                 opts->flags & REBASE_VERBOSE ? "t" : "");
 244         add_var(&script_snippet, "diffstat",
 245                 opts->flags & REBASE_DIFFSTAT ? "t" : "");
 246         add_var(&script_snippet, "force_rebase",
 247                 opts->flags & REBASE_FORCE ? "t" : "");
 248         if (opts->switch_to)
 249                 add_var(&script_snippet, "switch_to", opts->switch_to);
 250         add_var(&script_snippet, "action", opts->action ? opts->action : "");
 251
 252         switch (opts->type) {
 253         case REBASE_AM:
 254                 backend = "git-rebase--am";
 255                 backend_func = "git_rebase__am";
 256                 break;
 257         case REBASE_INTERACTIVE:
 258                 backend = "git-rebase--interactive";
 259                 backend_func = "git_rebase__interactive";
 260                 break;
 261         case REBASE_MERGE:
 262                 backend = "git-rebase--merge";
 263                 backend_func = "git_rebase__merge";
 264                 break;
 265         case REBASE_PRESERVE_MERGES:
 266                 backend = "git-rebase--preserve-merges";
 267                 backend_func = "git_rebase__preserve_merges";
 268                 break;
 269         default:
 270                 BUG("Unhandled rebase type %d", opts->type);
 271                 break;
 272         }
 273
 274         strbuf_addf(&script_snippet,
 275                     ". git-sh-setup && . git-rebase--common &&"
 276                     " . %s && %s", backend, backend_func);
 277         argv[0] = script_snippet.buf;
 278
 279         status = run_command_v_opt(argv, RUN_USING_SHELL);
 280         if (opts->dont_finish_rebase)
 281                 ; /* do nothing */
 282         else if (status == 0) {
 283                 if (!file_exists(state_dir_path("stopped-sha", opts)))
 284                         finish_rebase(opts);
 285         } else if (status == 2) {
 286                 struct strbuf dir = STRBUF_INIT;
 287
 288                 apply_autostash();
 289                 strbuf_addstr(&dir, opts->state_dir);
 290                 remove_dir_recursively(&dir, 0);
 291                 strbuf_release(&dir);
 292                 die("Nothing to do");
 293         }
 294
 295         strbuf_release(&script_snippet);
 296
 297         return status ? -1 : 0;
 298 }
 299
 300 #define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
 301
 302 static int reset_head(struct object_id *oid, const char *action,
 303                       const char *switch_to_branch, int detach_head)
 304 {
 305         struct object_id head_oid;
 306         struct tree_desc desc;
 307         struct lock_file lock = LOCK_INIT;
 308         struct unpack_trees_options unpack_tree_opts;
 309         struct tree *tree;
 310         const char *reflog_action;
 311         struct strbuf msg = STRBUF_INIT;
 312         size_t prefix_len;
 313         struct object_id *orig = NULL, oid_orig,
 314                 *old_orig = NULL, oid_old_orig;
 315         int ret = 0;
 316
 317         if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
 318                 BUG("Not a fully qualified branch: '%s'", switch_to_branch);
 319
 320         if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
 321                 return -1;
 322
 323         if (!oid) {
 324                 if (get_oid("HEAD", &head_oid)) {
 325                         rollback_lock_file(&lock);
 326                         return error(_("could not determine HEAD revision"));
 327                 }
 328                 oid = &head_oid;
 329         }
 330
 331         memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
 332         setup_unpack_trees_porcelain(&unpack_tree_opts, action);
 333         unpack_tree_opts.head_idx = 1;
 334         unpack_tree_opts.src_index = the_repository->index;
 335         unpack_tree_opts.dst_index = the_repository->index;
 336         unpack_tree_opts.fn = oneway_merge;
 337         unpack_tree_opts.update = 1;
 338         unpack_tree_opts.merge = 1;
 339         if (!detach_head)
 340                 unpack_tree_opts.reset = 1;
 341
 342         if (read_index_unmerged(the_repository->index) < 0) {
 343                 rollback_lock_file(&lock);
 344                 return error(_("could not read index"));
 345         }
 346
 347         if (!fill_tree_descriptor(&desc, oid)) {
 348                 error(_("failed to find tree of %s"), oid_to_hex(oid));
 349                 rollback_lock_file(&lock);
 350                 free((void *)desc.buffer);
 351                 return -1;
 352         }
 353
 354         if (unpack_trees(1, &desc, &unpack_tree_opts)) {
 355                 rollback_lock_file(&lock);
 356                 free((void *)desc.buffer);
 357                 return -1;
 358         }
 359
 360         tree = parse_tree_indirect(oid);
 361         prime_cache_tree(the_repository->index, tree);
 362
 363         if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0)
 364                 ret = error(_("could not write index"));
 365         free((void *)desc.buffer);
 366
 367         if (ret)
 368                 return ret;
 369
 370         reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
 371         strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
 372         prefix_len = msg.len;
 373
 374         if (!get_oid("ORIG_HEAD", &oid_old_orig))
 375                 old_orig = &oid_old_orig;
 376         if (!get_oid("HEAD", &oid_orig)) {
 377                 orig = &oid_orig;
 378                 strbuf_addstr(&msg, "updating ORIG_HEAD");
 379                 update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
 380                            UPDATE_REFS_MSG_ON_ERR);
 381         } else if (old_orig)
 382                 delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
 383         strbuf_setlen(&msg, prefix_len);
 384         strbuf_addstr(&msg, "updating HEAD");
 385         if (!switch_to_branch)
 386                 ret = update_ref(msg.buf, "HEAD", oid, orig, REF_NO_DEREF,
 387                                  UPDATE_REFS_MSG_ON_ERR);
 388         else {
 389                 ret = create_symref("HEAD", switch_to_branch, msg.buf);
 390                 if (!ret)
 391                         ret = update_ref(msg.buf, "HEAD", oid, NULL, 0,
 392                                          UPDATE_REFS_MSG_ON_ERR);
 393         }
 394
 395         strbuf_release(&msg);
 396         return ret;
 397 }
 398
 399 static int rebase_config(const char *var, const char *value, void *data)
 400 {
 401         struct rebase_options *opts = data;
 402
 403         if (!strcmp(var, "rebase.stat")) {
 404                 if (git_config_bool(var, value))
 405                         opts->flags |= REBASE_DIFFSTAT;
 406                 else
 407                         opts->flags &= !REBASE_DIFFSTAT;
 408                 return 0;
 409         }
 410
 411         return git_default_config(var, value, data);
 412 }
 413
 414 /*
 415  * Determines whether the commits in from..to are linear, i.e. contain
 416  * no merge commits. This function *expects* `from` to be an ancestor of
 417  * `to`.
 418  */
 419 static int is_linear_history(struct commit *from, struct commit *to)
 420 {
 421         while (to && to != from) {
 422                 parse_commit(to);
 423                 if (!to->parents)
 424                         return 1;
 425                 if (to->parents->next)
 426                         return 0;
 427                 to = to->parents->item;
 428         }
 429         return 1;
 430 }
 431
 432 static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
 433                             struct object_id *merge_base)
 434 {
 435         struct commit *head = lookup_commit(the_repository, head_oid);
 436         struct commit_list *merge_bases;
 437         int res;
 438
 439         if (!head)
 440                 return 0;
 441
 442         merge_bases = get_merge_bases(onto, head);
 443         if (merge_bases && !merge_bases->next) {
 444                 oidcpy(merge_base, &merge_bases->item->object.oid);
 445                 res = !oidcmp(merge_base, &onto->object.oid);
 446         } else {
 447                 oidcpy(merge_base, &null_oid);
 448                 res = 0;
 449         }
 450         free_commit_list(merge_bases);
 451         return res && is_linear_history(onto, head);
 452 }
 453
 454 int cmd_rebase(int argc, const char **argv, const char *prefix)
 455 {
 456         struct rebase_options options = {
 457                 .type = REBASE_UNSPECIFIED,
 458                 .flags = REBASE_NO_QUIET,
 459                 .git_am_opt = STRBUF_INIT,
 460         };
 461         const char *branch_name;
 462         int ret, flags, total_argc, in_progress = 0;
 463         int ok_to_skip_pre_rebase = 0;
 464         struct strbuf msg = STRBUF_INIT;
 465         struct strbuf revisions = STRBUF_INIT;
 466         struct strbuf buf = STRBUF_INIT;
 467         struct object_id merge_base;
 468         enum {
 469                 NO_ACTION,
 470                 ACTION_CONTINUE,
 471         } action = NO_ACTION;
 472         struct option builtin_rebase_options[] = {
 473                 OPT_STRING(0, "onto", &options.onto_name,
 474                            N_("revision"),
 475                            N_("rebase onto given branch instead of upstream")),
 476                 OPT_BOOL(0, "no-verify", &ok_to_skip_pre_rebase,
 477                          N_("allow pre-rebase hook to run")),
 478                 OPT_NEGBIT('q', "quiet", &options.flags,
 479                            N_("be quiet. implies --no-stat"),
 480                            REBASE_NO_QUIET| REBASE_VERBOSE | REBASE_DIFFSTAT),
 481                 OPT_BIT('v', "verbose", &options.flags,
 482                         N_("display a diffstat of what changed upstream"),
 483                         REBASE_NO_QUIET | REBASE_VERBOSE | REBASE_DIFFSTAT),
 484                 {OPTION_NEGBIT, 'n', "no-stat", &options.flags, NULL,
 485                         N_("do not show diffstat of what changed upstream"),
 486                         PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
 487                 OPT_BIT('f', "force-rebase", &options.flags,
 488                         N_("cherry-pick all commits, even if unchanged"),
 489                         REBASE_FORCE),
 490                 OPT_BIT(0, "no-ff", &options.flags,
 491                         N_("cherry-pick all commits, even if unchanged"),
 492                         REBASE_FORCE),
 493                 OPT_CMDMODE(0, "continue", &action, N_("continue"),
 494                             ACTION_CONTINUE),
 495                 OPT_END(),
 496         };
 497
 498         /*
 499          * NEEDSWORK: Once the builtin rebase has been tested enough
 500          * and git-legacy-rebase.sh is retired to contrib/, this preamble
 501          * can be removed.
 502          */
 503
 504         if (!use_builtin_rebase()) {
 505                 const char *path = mkpath("%s/git-legacy-rebase",
 506                                           git_exec_path());
 507
 508                 if (sane_execvp(path, (char **)argv) < 0)
 509                         die_errno(_("could not exec %s"), path);
 510                 else
 511                         BUG("sane_execvp() returned???");
 512         }
 513
 514         if (argc == 2 && !strcmp(argv[1], "-h"))
 515                 usage_with_options(builtin_rebase_usage,
 516                                    builtin_rebase_options);
 517
 518         prefix = setup_git_directory();
 519         trace_repo_setup(prefix);
 520         setup_work_tree();
 521
 522         git_config(rebase_config, &options);
 523
 524         if (is_directory(apply_dir())) {
 525                 options.type = REBASE_AM;
 526                 options.state_dir = apply_dir();
 527         } else if (is_directory(merge_dir())) {
 528                 strbuf_reset(&buf);
 529                 strbuf_addf(&buf, "%s/rewritten", merge_dir());
 530                 if (is_directory(buf.buf)) {
 531                         options.type = REBASE_PRESERVE_MERGES;
 532                         options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 533                 } else {
 534                         strbuf_reset(&buf);
 535                         strbuf_addf(&buf, "%s/interactive", merge_dir());
 536                         if(file_exists(buf.buf)) {
 537                                 options.type = REBASE_INTERACTIVE;
 538                                 options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 539                         } else
 540                                 options.type = REBASE_MERGE;
 541                 }
 542                 options.state_dir = merge_dir();
 543         }
 544
 545         if (options.type != REBASE_UNSPECIFIED)
 546                 in_progress = 1;
 547
 548         total_argc = argc;
 549         argc = parse_options(argc, argv, prefix,
 550                              builtin_rebase_options,
 551                              builtin_rebase_usage, 0);
 552
 553         if (action != NO_ACTION && total_argc != 2) {
 554                 usage_with_options(builtin_rebase_usage,
 555                                    builtin_rebase_options);
 556         }
 557
 558         if (argc > 2)
 559                 usage_with_options(builtin_rebase_usage,
 560                                    builtin_rebase_options);
 561
 562         switch (action) {
 563         case ACTION_CONTINUE: {
 564                 struct object_id head;
 565                 struct lock_file lock_file = LOCK_INIT;
 566                 int fd;
 567
 568                 options.action = "continue";
 569
 570                 /* Sanity check */
 571                 if (get_oid("HEAD", &head))
 572                         die(_("Cannot read HEAD"));
 573
 574                 fd = hold_locked_index(&lock_file, 0);
 575                 if (read_index(the_repository->index) < 0)
 576                         die(_("could not read index"));
 577                 refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL,
 578                               NULL);
 579                 if (0 <= fd)
 580                         update_index_if_able(the_repository->index,
 581                                              &lock_file);
 582                 rollback_lock_file(&lock_file);
 583
 584                 if (has_unstaged_changes(1)) {
 585                         puts(_("You must edit all merge conflicts and then\n"
 586                                "mark them as resolved using git add"));
 587                         exit(1);
 588                 }
 589                 if (read_basic_state(&options))
 590                         exit(1);
 591                 goto run_rebase;
 592         }
 593         default:
 594                 die("TODO");
 595         }
 596
 597         /* Make sure no rebase is in progress */
 598         if (in_progress) {
 599                 const char *last_slash = strrchr(options.state_dir, '/');
 600                 const char *state_dir_base =
 601                         last_slash ? last_slash + 1 : options.state_dir;
 602                 const char *cmd_live_rebase =
 603                         "git rebase (--continue | --abort | --skip)";
 604                 strbuf_reset(&buf);
 605                 strbuf_addf(&buf, "rm -fr \"%s\"", options.state_dir);
 606                 die(_("It seems that there is already a %s directory, and\n"
 607                       "I wonder if you are in the middle of another rebase.  "
 608                       "If that is the\n"
 609                       "case, please try\n\t%s\n"
 610                       "If that is not the case, please\n\t%s\n"
 611                       "and run me again.  I am stopping in case you still "
 612                       "have something\n"
 613                       "valuable there.\n"),
 614                     state_dir_base, cmd_live_rebase, buf.buf);
 615         }
 616
 617         if (!(options.flags & REBASE_NO_QUIET))
 618                 strbuf_addstr(&options.git_am_opt, " -q");
 619
 620         switch (options.type) {
 621         case REBASE_MERGE:
 622         case REBASE_INTERACTIVE:
 623         case REBASE_PRESERVE_MERGES:
 624                 options.state_dir = merge_dir();
 625                 break;
 626         case REBASE_AM:
 627                 options.state_dir = apply_dir();
 628                 break;
 629         default:
 630                 /* the default rebase backend is `--am` */
 631                 options.type = REBASE_AM;
 632                 options.state_dir = apply_dir();
 633                 break;
 634         }
 635
 636         if (!options.root) {
 637                 if (argc < 1)
 638                         die("TODO: handle @{upstream}");
 639                 else {
 640                         options.upstream_name = argv[0];
 641                         argc--;
 642                         argv++;
 643                         if (!strcmp(options.upstream_name, "-"))
 644                                 options.upstream_name = "@{-1}";
 645                 }
 646                 options.upstream = peel_committish(options.upstream_name);
 647                 if (!options.upstream)
 648                         die(_("invalid upstream '%s'"), options.upstream_name);
 649                 options.upstream_arg = options.upstream_name;
 650         } else
 651                 die("TODO: upstream for --root");
 652
 653         /* Make sure the branch to rebase onto is valid. */
 654         if (!options.onto_name)
 655                 options.onto_name = options.upstream_name;
 656         if (strstr(options.onto_name, "...")) {
 657                 if (get_oid_mb(options.onto_name, &merge_base) < 0)
 658                         die(_("'%s': need exactly one merge base"),
 659                             options.onto_name);
 660                 options.onto = lookup_commit_or_die(&merge_base,
 661                                                     options.onto_name);
 662         } else {
 663                 options.onto = peel_committish(options.onto_name);
 664                 if (!options.onto)
 665                         die(_("Does not point to a valid commit '%s'"),
 666                                 options.onto_name);
 667         }
 668
 669         /*
 670          * If the branch to rebase is given, that is the branch we will rebase
 671          * branch_name -- branch/commit being rebased, or
 672          *                HEAD (already detached)
 673          * orig_head -- commit object name of tip of the branch before rebasing
 674          * head_name -- refs/heads/<that-branch> or NULL (detached HEAD)
 675          */
 676         if (argc == 1) {
 677                 /* Is it "rebase other branchname" or "rebase other commit"? */
 678                 branch_name = argv[0];
 679                 options.switch_to = argv[0];
 680
 681                 /* Is it a local branch? */
 682                 strbuf_reset(&buf);
 683                 strbuf_addf(&buf, "refs/heads/%s", branch_name);
 684                 if (!read_ref(buf.buf, &options.orig_head))
 685                         options.head_name = xstrdup(buf.buf);
 686                 /* If not is it a valid ref (branch or commit)? */
 687                 else if (!get_oid(branch_name, &options.orig_head))
 688                         options.head_name = NULL;
 689                 else
 690                         die(_("fatal: no such branch/commit '%s'"),
 691                             branch_name);
 692         } else if (argc == 0) {
 693                 /* Do not need to switch branches, we are already on it. */
 694                 options.head_name =
 695                         xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
 696                                          &flags));
 697                 if (!options.head_name)
 698                         die(_("No such ref: %s"), "HEAD");
 699                 if (flags & REF_ISSYMREF) {
 700                         if (!skip_prefix(options.head_name,
 701                                          "refs/heads/", &branch_name))
 702                                 branch_name = options.head_name;
 703
 704                 } else {
 705                         free(options.head_name);
 706                         options.head_name = NULL;
 707                         branch_name = "HEAD";
 708                 }
 709                 if (get_oid("HEAD", &options.orig_head))
 710                         die(_("Could not resolve HEAD to a revision"));
 711         } else
 712                 BUG("unexpected number of arguments left to parse");
 713
 714         if (read_index(the_repository->index) < 0)
 715                 die(_("could not read index"));
 716
 717         if (require_clean_work_tree("rebase",
 718                                     _("Please commit or stash them."), 1, 1)) {
 719                 ret = 1;
 720                 goto cleanup;
 721         }
 722
 723         /*
 724          * Now we are rebasing commits upstream..orig_head (or with --root,
 725          * everything leading up to orig_head) on top of onto.
 726          */
 727
 728         /*
 729          * Check if we are already based on onto with linear history,
 730          * but this should be done only when upstream and onto are the same
 731          * and if this is not an interactive rebase.
 732          */
 733         if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
 734             !is_interactive(&options) && !options.restrict_revision &&
 735             !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
 736                 int flag;
 737
 738                 if (!(options.flags & REBASE_FORCE)) {
 739                         /* Lazily switch to the target branch if needed... */
 740                         if (options.switch_to) {
 741                                 struct object_id oid;
 742
 743                                 if (get_oid(options.switch_to, &oid) < 0) {
 744                                         ret = !!error(_("could not parse '%s'"),
 745                                                       options.switch_to);
 746                                         goto cleanup;
 747                                 }
 748
 749                                 strbuf_reset(&buf);
 750                                 strbuf_addf(&buf, "rebase: checkout %s",
 751                                             options.switch_to);
 752                                 if (reset_head(&oid, "checkout",
 753                                                options.head_name, 0) < 0) {
 754                                         ret = !!error(_("could not switch to "
 755                                                         "%s"),
 756                                                       options.switch_to);
 757                                         goto cleanup;
 758                                 }
 759                         }
 760
 761                         if (!(options.flags & REBASE_NO_QUIET))
 762                                 ; /* be quiet */
 763                         else if (!strcmp(branch_name, "HEAD") &&
 764                                  resolve_ref_unsafe("HEAD", 0, NULL, &flag))
 765                                 puts(_("HEAD is up to date."));
 766                         else
 767                                 printf(_("Current branch %s is up to date.\n"),
 768                                        branch_name);
 769                         ret = !!finish_rebase(&options);
 770                         goto cleanup;
 771                 } else if (!(options.flags & REBASE_NO_QUIET))
 772                         ; /* be quiet */
 773                 else if (!strcmp(branch_name, "HEAD") &&
 774                          resolve_ref_unsafe("HEAD", 0, NULL, &flag))
 775                         puts(_("HEAD is up to date, rebase forced."));
 776                 else
 777                         printf(_("Current branch %s is up to date, rebase "
 778                                  "forced.\n"), branch_name);
 779         }
 780
 781         /* If a hook exists, give it a chance to interrupt*/
 782         if (!ok_to_skip_pre_rebase &&
 783             run_hook_le(NULL, "pre-rebase", options.upstream_arg,
 784                         argc ? argv[0] : NULL, NULL))
 785                 die(_("The pre-rebase hook refused to rebase."));
 786
 787         if (options.flags & REBASE_DIFFSTAT) {
 788                 struct diff_options opts;
 789
 790                 if (options.flags & REBASE_VERBOSE)
 791                         printf(_("Changes from %s to %s:\n"),
 792                                 oid_to_hex(&merge_base),
 793                                 oid_to_hex(&options.onto->object.oid));
 794
 795                 /* We want color (if set), but no pager */
 796                 diff_setup(&opts);
 797                 opts.stat_width = -1; /* use full terminal width */
 798                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
 799                 opts.output_format |=
 800                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 801                 opts.detect_rename = DIFF_DETECT_RENAME;
 802                 diff_setup_done(&opts);
 803                 diff_tree_oid(&merge_base, &options.onto->object.oid,
 804                               "", &opts);
 805                 diffcore_std(&opts);
 806                 diff_flush(&opts);
 807         }
 808
 809         /* Detach HEAD and reset the tree */
 810         if (options.flags & REBASE_NO_QUIET)
 811                 printf(_("First, rewinding head to replay your work on top of "
 812                          "it...\n"));
 813
 814         strbuf_addf(&msg, "rebase: checkout %s", options.onto_name);
 815         if (reset_head(&options.onto->object.oid, "checkout", NULL, 1))
 816                 die(_("Could not detach HEAD"));
 817         strbuf_release(&msg);
 818
 819         strbuf_addf(&revisions, "%s..%s",
 820                     options.root ? oid_to_hex(&options.onto->object.oid) :
 821                     (options.restrict_revision ?
 822                      oid_to_hex(&options.restrict_revision->object.oid) :
 823                      oid_to_hex(&options.upstream->object.oid)),
 824                     oid_to_hex(&options.orig_head));
 825
 826         options.revisions = revisions.buf;
 827
 828 run_rebase:
 829         ret = !!run_specific_rebase(&options);
 830
 831 cleanup:
 832         strbuf_release(&revisions);
 833         free(options.head_name);
 834         return ret;
 835 }