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 #include "commit-reach.h"
  25 #include "rerere.h"
  26 #include "branch.h"
  27
  28 static char const * const builtin_rebase_usage[] = {
  29         N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
  30                 "[<upstream>] [<branch>]"),
  31         N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
  32                 "--root [<branch>]"),
  33         N_("git rebase --continue | --abort | --skip | --edit-todo"),
  34         NULL
  35 };
  36
  37 static GIT_PATH_FUNC(apply_dir, "rebase-apply")
  38 static GIT_PATH_FUNC(merge_dir, "rebase-merge")
  39
  40 enum rebase_type {
  41         REBASE_UNSPECIFIED = -1,
  42         REBASE_AM,
  43         REBASE_MERGE,
  44         REBASE_INTERACTIVE,
  45         REBASE_PRESERVE_MERGES
  46 };
  47
  48 static int use_builtin_rebase(void)
  49 {
  50         struct child_process cp = CHILD_PROCESS_INIT;
  51         struct strbuf out = STRBUF_INIT;
  52         int ret, env = git_env_bool("GIT_TEST_REBASE_USE_BUILTIN", -1);
  53
  54         if (env != -1)
  55                 return env;
  56
  57         argv_array_pushl(&cp.args,
  58                          "config", "--bool", "rebase.usebuiltin", NULL);
  59         cp.git_cmd = 1;
  60         if (capture_command(&cp, &out, 6)) {
  61                 strbuf_release(&out);
  62                 return 1;
  63         }
  64
  65         strbuf_trim(&out);
  66         ret = !strcmp("true", out.buf);
  67         strbuf_release(&out);
  68         return ret;
  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 object_id *squash_onto;
  85         struct commit *restrict_revision;
  86         int dont_finish_rebase;
  87         enum {
  88                 REBASE_NO_QUIET = 1<<0,
  89                 REBASE_VERBOSE = 1<<1,
  90                 REBASE_DIFFSTAT = 1<<2,
  91                 REBASE_FORCE = 1<<3,
  92                 REBASE_INTERACTIVE_EXPLICIT = 1<<4,
  93         } flags;
  94         struct argv_array git_am_opts;
  95         const char *action;
  96         int signoff;
  97         int allow_rerere_autoupdate;
  98         int keep_empty;
  99         int autosquash;
 100         char *gpg_sign_opt;
 101         int autostash;
 102         char *cmd;
 103         int allow_empty_message;
 104         int rebase_merges, rebase_cousins;
 105         char *strategy, *strategy_opts;
 106         struct strbuf git_format_patch_opt;
 107 };
 108
 109 static int is_interactive(struct rebase_options *opts)
 110 {
 111         return opts->type == REBASE_INTERACTIVE ||
 112                 opts->type == REBASE_PRESERVE_MERGES;
 113 }
 114
 115 static void imply_interactive(struct rebase_options *opts, const char *option)
 116 {
 117         switch (opts->type) {
 118         case REBASE_AM:
 119                 die(_("%s requires an interactive rebase"), option);
 120                 break;
 121         case REBASE_INTERACTIVE:
 122         case REBASE_PRESERVE_MERGES:
 123                 break;
 124         case REBASE_MERGE:
 125                 /* we silently *upgrade* --merge to --interactive if needed */
 126         default:
 127                 opts->type = REBASE_INTERACTIVE; /* implied */
 128                 break;
 129         }
 130 }
 131
 132 /* Returns the filename prefixed by the state_dir */
 133 static const char *state_dir_path(const char *filename, struct rebase_options *opts)
 134 {
 135         static struct strbuf path = STRBUF_INIT;
 136         static size_t prefix_len;
 137
 138         if (!prefix_len) {
 139                 strbuf_addf(&path, "%s/", opts->state_dir);
 140                 prefix_len = path.len;
 141         }
 142
 143         strbuf_setlen(&path, prefix_len);
 144         strbuf_addstr(&path, filename);
 145         return path.buf;
 146 }
 147
 148 /* Read one file, then strip line endings */
 149 static int read_one(const char *path, struct strbuf *buf)
 150 {
 151         if (strbuf_read_file(buf, path, 0) < 0)
 152                 return error_errno(_("could not read '%s'"), path);
 153         strbuf_trim_trailing_newline(buf);
 154         return 0;
 155 }
 156
 157 /* Initialize the rebase options from the state directory. */
 158 static int read_basic_state(struct rebase_options *opts)
 159 {
 160         struct strbuf head_name = STRBUF_INIT;
 161         struct strbuf buf = STRBUF_INIT;
 162         struct object_id oid;
 163
 164         if (read_one(state_dir_path("head-name", opts), &head_name) ||
 165             read_one(state_dir_path("onto", opts), &buf))
 166                 return -1;
 167         opts->head_name = starts_with(head_name.buf, "refs/") ?
 168                 xstrdup(head_name.buf) : NULL;
 169         strbuf_release(&head_name);
 170         if (get_oid(buf.buf, &oid))
 171                 return error(_("could not get 'onto': '%s'"), buf.buf);
 172         opts->onto = lookup_commit_or_die(&oid, buf.buf);
 173
 174         /*
 175          * We always write to orig-head, but interactive rebase used to write to
 176          * head. Fall back to reading from head to cover for the case that the
 177          * user upgraded git with an ongoing interactive rebase.
 178          */
 179         strbuf_reset(&buf);
 180         if (file_exists(state_dir_path("orig-head", opts))) {
 181                 if (read_one(state_dir_path("orig-head", opts), &buf))
 182                         return -1;
 183         } else if (read_one(state_dir_path("head", opts), &buf))
 184                 return -1;
 185         if (get_oid(buf.buf, &opts->orig_head))
 186                 return error(_("invalid orig-head: '%s'"), buf.buf);
 187
 188         strbuf_reset(&buf);
 189         if (read_one(state_dir_path("quiet", opts), &buf))
 190                 return -1;
 191         if (buf.len)
 192                 opts->flags &= ~REBASE_NO_QUIET;
 193         else
 194                 opts->flags |= REBASE_NO_QUIET;
 195
 196         if (file_exists(state_dir_path("verbose", opts)))
 197                 opts->flags |= REBASE_VERBOSE;
 198
 199         if (file_exists(state_dir_path("signoff", opts))) {
 200                 opts->signoff = 1;
 201                 opts->flags |= REBASE_FORCE;
 202         }
 203
 204         if (file_exists(state_dir_path("allow_rerere_autoupdate", opts))) {
 205                 strbuf_reset(&buf);
 206                 if (read_one(state_dir_path("allow_rerere_autoupdate", opts),
 207                             &buf))
 208                         return -1;
 209                 if (!strcmp(buf.buf, "--rerere-autoupdate"))
 210                         opts->allow_rerere_autoupdate = 1;
 211                 else if (!strcmp(buf.buf, "--no-rerere-autoupdate"))
 212                         opts->allow_rerere_autoupdate = 0;
 213                 else
 214                         warning(_("ignoring invalid allow_rerere_autoupdate: "
 215                                   "'%s'"), buf.buf);
 216         } else
 217                 opts->allow_rerere_autoupdate = -1;
 218
 219         if (file_exists(state_dir_path("gpg_sign_opt", opts))) {
 220                 strbuf_reset(&buf);
 221                 if (read_one(state_dir_path("gpg_sign_opt", opts),
 222                             &buf))
 223                         return -1;
 224                 free(opts->gpg_sign_opt);
 225                 opts->gpg_sign_opt = xstrdup(buf.buf);
 226         }
 227
 228         if (file_exists(state_dir_path("strategy", opts))) {
 229                 strbuf_reset(&buf);
 230                 if (read_one(state_dir_path("strategy", opts), &buf))
 231                         return -1;
 232                 free(opts->strategy);
 233                 opts->strategy = xstrdup(buf.buf);
 234         }
 235
 236         if (file_exists(state_dir_path("strategy_opts", opts))) {
 237                 strbuf_reset(&buf);
 238                 if (read_one(state_dir_path("strategy_opts", opts), &buf))
 239                         return -1;
 240                 free(opts->strategy_opts);
 241                 opts->strategy_opts = xstrdup(buf.buf);
 242         }
 243
 244         strbuf_release(&buf);
 245
 246         return 0;
 247 }
 248
 249 static int apply_autostash(struct rebase_options *opts)
 250 {
 251         const char *path = state_dir_path("autostash", opts);
 252         struct strbuf autostash = STRBUF_INIT;
 253         struct child_process stash_apply = CHILD_PROCESS_INIT;
 254
 255         if (!file_exists(path))
 256                 return 0;
 257
 258         if (read_one(path, &autostash))
 259                 return error(_("Could not read '%s'"), path);
 260         /* Ensure that the hash is not mistaken for a number */
 261         strbuf_addstr(&autostash, "^0");
 262         argv_array_pushl(&stash_apply.args,
 263                          "stash", "apply", autostash.buf, NULL);
 264         stash_apply.git_cmd = 1;
 265         stash_apply.no_stderr = stash_apply.no_stdout =
 266                 stash_apply.no_stdin = 1;
 267         if (!run_command(&stash_apply))
 268                 printf(_("Applied autostash.\n"));
 269         else {
 270                 struct argv_array args = ARGV_ARRAY_INIT;
 271                 int res = 0;
 272
 273                 argv_array_pushl(&args,
 274                                  "stash", "store", "-m", "autostash", "-q",
 275                                  autostash.buf, NULL);
 276                 if (run_command_v_opt(args.argv, RUN_GIT_CMD))
 277                         res = error(_("Cannot store %s"), autostash.buf);
 278                 argv_array_clear(&args);
 279                 strbuf_release(&autostash);
 280                 if (res)
 281                         return res;
 282
 283                 fprintf(stderr,
 284                         _("Applying autostash resulted in conflicts.\n"
 285                           "Your changes are safe in the stash.\n"
 286                           "You can run \"git stash pop\" or \"git stash drop\" "
 287                           "at any time.\n"));
 288         }
 289
 290         strbuf_release(&autostash);
 291         return 0;
 292 }
 293
 294 static int finish_rebase(struct rebase_options *opts)
 295 {
 296         struct strbuf dir = STRBUF_INIT;
 297         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 298
 299         delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 300         apply_autostash(opts);
 301         close_all_packs(the_repository->objects);
 302         /*
 303          * We ignore errors in 'gc --auto', since the
 304          * user should see them.
 305          */
 306         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 307         strbuf_addstr(&dir, opts->state_dir);
 308         remove_dir_recursively(&dir, 0);
 309         strbuf_release(&dir);
 310
 311         return 0;
 312 }
 313
 314 static struct commit *peel_committish(const char *name)
 315 {
 316         struct object *obj;
 317         struct object_id oid;
 318
 319         if (get_oid(name, &oid))
 320                 return NULL;
 321         obj = parse_object(the_repository, &oid);
 322         return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
 323 }
 324
 325 static void add_var(struct strbuf *buf, const char *name, const char *value)
 326 {
 327         if (!value)
 328                 strbuf_addf(buf, "unset %s; ", name);
 329         else {
 330                 strbuf_addf(buf, "%s=", name);
 331                 sq_quote_buf(buf, value);
 332                 strbuf_addstr(buf, "; ");
 333         }
 334 }
 335
 336 static const char *resolvemsg =
 337 N_("Resolve all conflicts manually, mark them as resolved with\n"
 338 "\"git add/rm <conflicted_files>\", then run \"git rebase --continue\".\n"
 339 "You can instead skip this commit: run \"git rebase --skip\".\n"
 340 "To abort and get back to the state before \"git rebase\", run "
 341 "\"git rebase --abort\".");
 342
 343 static int run_specific_rebase(struct rebase_options *opts)
 344 {
 345         const char *argv[] = { NULL, NULL };
 346         struct strbuf script_snippet = STRBUF_INIT, buf = STRBUF_INIT;
 347         int status;
 348         const char *backend, *backend_func;
 349
 350         if (opts->type == REBASE_INTERACTIVE) {
 351                 /* Run builtin interactive rebase */
 352                 struct child_process child = CHILD_PROCESS_INIT;
 353
 354                 argv_array_pushf(&child.env_array, "GIT_CHERRY_PICK_HELP=%s",
 355                                  resolvemsg);
 356                 if (!(opts->flags & REBASE_INTERACTIVE_EXPLICIT)) {
 357                         argv_array_push(&child.env_array,
 358                                         "GIT_SEQUENCE_EDITOR=:");
 359                         opts->autosquash = 0;
 360                 }
 361
 362                 child.git_cmd = 1;
 363                 argv_array_push(&child.args, "rebase--interactive");
 364
 365                 if (opts->action)
 366                         argv_array_pushf(&child.args, "--%s", opts->action);
 367                 if (opts->keep_empty)
 368                         argv_array_push(&child.args, "--keep-empty");
 369                 if (opts->rebase_merges)
 370                         argv_array_push(&child.args, "--rebase-merges");
 371                 if (opts->rebase_cousins)
 372                         argv_array_push(&child.args, "--rebase-cousins");
 373                 if (opts->autosquash)
 374                         argv_array_push(&child.args, "--autosquash");
 375                 if (opts->flags & REBASE_VERBOSE)
 376                         argv_array_push(&child.args, "--verbose");
 377                 if (opts->flags & REBASE_FORCE)
 378                         argv_array_push(&child.args, "--no-ff");
 379                 if (opts->restrict_revision)
 380                         argv_array_pushf(&child.args,
 381                                          "--restrict-revision=^%s",
 382                                          oid_to_hex(&opts->restrict_revision->object.oid));
 383                 if (opts->upstream)
 384                         argv_array_pushf(&child.args, "--upstream=%s",
 385                                          oid_to_hex(&opts->upstream->object.oid));
 386                 if (opts->onto)
 387                         argv_array_pushf(&child.args, "--onto=%s",
 388                                          oid_to_hex(&opts->onto->object.oid));
 389                 if (opts->squash_onto)
 390                         argv_array_pushf(&child.args, "--squash-onto=%s",
 391                                          oid_to_hex(opts->squash_onto));
 392                 if (opts->onto_name)
 393                         argv_array_pushf(&child.args, "--onto-name=%s",
 394                                          opts->onto_name);
 395                 argv_array_pushf(&child.args, "--head-name=%s",
 396                                  opts->head_name ?
 397                                  opts->head_name : "detached HEAD");
 398                 if (opts->strategy)
 399                         argv_array_pushf(&child.args, "--strategy=%s",
 400                                          opts->strategy);
 401                 if (opts->strategy_opts)
 402                         argv_array_pushf(&child.args, "--strategy-opts=%s",
 403                                          opts->strategy_opts);
 404                 if (opts->switch_to)
 405                         argv_array_pushf(&child.args, "--switch-to=%s",
 406                                          opts->switch_to);
 407                 if (opts->cmd)
 408                         argv_array_pushf(&child.args, "--cmd=%s", opts->cmd);
 409                 if (opts->allow_empty_message)
 410                         argv_array_push(&child.args, "--allow-empty-message");
 411                 if (opts->allow_rerere_autoupdate > 0)
 412                         argv_array_push(&child.args, "--rerere-autoupdate");
 413                 else if (opts->allow_rerere_autoupdate == 0)
 414                         argv_array_push(&child.args, "--no-rerere-autoupdate");
 415                 if (opts->gpg_sign_opt)
 416                         argv_array_push(&child.args, opts->gpg_sign_opt);
 417                 if (opts->signoff)
 418                         argv_array_push(&child.args, "--signoff");
 419
 420                 status = run_command(&child);
 421                 goto finished_rebase;
 422         }
 423
 424         add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
 425         add_var(&script_snippet, "state_dir", opts->state_dir);
 426
 427         add_var(&script_snippet, "upstream_name", opts->upstream_name);
 428         add_var(&script_snippet, "upstream", opts->upstream ?
 429                 oid_to_hex(&opts->upstream->object.oid) : NULL);
 430         add_var(&script_snippet, "head_name",
 431                 opts->head_name ? opts->head_name : "detached HEAD");
 432         add_var(&script_snippet, "orig_head", oid_to_hex(&opts->orig_head));
 433         add_var(&script_snippet, "onto", opts->onto ?
 434                 oid_to_hex(&opts->onto->object.oid) : NULL);
 435         add_var(&script_snippet, "onto_name", opts->onto_name);
 436         add_var(&script_snippet, "revisions", opts->revisions);
 437         add_var(&script_snippet, "restrict_revision", opts->restrict_revision ?
 438                 oid_to_hex(&opts->restrict_revision->object.oid) : NULL);
 439         add_var(&script_snippet, "GIT_QUIET",
 440                 opts->flags & REBASE_NO_QUIET ? "" : "t");
 441         sq_quote_argv_pretty(&buf, opts->git_am_opts.argv);
 442         add_var(&script_snippet, "git_am_opt", buf.buf);
 443         strbuf_release(&buf);
 444         add_var(&script_snippet, "verbose",
 445                 opts->flags & REBASE_VERBOSE ? "t" : "");
 446         add_var(&script_snippet, "diffstat",
 447                 opts->flags & REBASE_DIFFSTAT ? "t" : "");
 448         add_var(&script_snippet, "force_rebase",
 449                 opts->flags & REBASE_FORCE ? "t" : "");
 450         if (opts->switch_to)
 451                 add_var(&script_snippet, "switch_to", opts->switch_to);
 452         add_var(&script_snippet, "action", opts->action ? opts->action : "");
 453         add_var(&script_snippet, "signoff", opts->signoff ? "--signoff" : "");
 454         add_var(&script_snippet, "allow_rerere_autoupdate",
 455                 opts->allow_rerere_autoupdate < 0 ? "" :
 456                 opts->allow_rerere_autoupdate ?
 457                 "--rerere-autoupdate" : "--no-rerere-autoupdate");
 458         add_var(&script_snippet, "keep_empty", opts->keep_empty ? "yes" : "");
 459         add_var(&script_snippet, "autosquash", opts->autosquash ? "t" : "");
 460         add_var(&script_snippet, "gpg_sign_opt", opts->gpg_sign_opt);
 461         add_var(&script_snippet, "cmd", opts->cmd);
 462         add_var(&script_snippet, "allow_empty_message",
 463                 opts->allow_empty_message ?  "--allow-empty-message" : "");
 464         add_var(&script_snippet, "rebase_merges",
 465                 opts->rebase_merges ? "t" : "");
 466         add_var(&script_snippet, "rebase_cousins",
 467                 opts->rebase_cousins ? "t" : "");
 468         add_var(&script_snippet, "strategy", opts->strategy);
 469         add_var(&script_snippet, "strategy_opts", opts->strategy_opts);
 470         add_var(&script_snippet, "rebase_root", opts->root ? "t" : "");
 471         add_var(&script_snippet, "squash_onto",
 472                 opts->squash_onto ? oid_to_hex(opts->squash_onto) : "");
 473         add_var(&script_snippet, "git_format_patch_opt",
 474                 opts->git_format_patch_opt.buf);
 475
 476         if (is_interactive(opts) &&
 477             !(opts->flags & REBASE_INTERACTIVE_EXPLICIT)) {
 478                 strbuf_addstr(&script_snippet,
 479                               "GIT_SEQUENCE_EDITOR=:; export GIT_SEQUENCE_EDITOR; ");
 480                 opts->autosquash = 0;
 481         }
 482
 483         switch (opts->type) {
 484         case REBASE_AM:
 485                 backend = "git-rebase--am";
 486                 backend_func = "git_rebase__am";
 487                 break;
 488         case REBASE_MERGE:
 489                 backend = "git-rebase--merge";
 490                 backend_func = "git_rebase__merge";
 491                 break;
 492         case REBASE_PRESERVE_MERGES:
 493                 backend = "git-rebase--preserve-merges";
 494                 backend_func = "git_rebase__preserve_merges";
 495                 break;
 496         default:
 497                 BUG("Unhandled rebase type %d", opts->type);
 498                 break;
 499         }
 500
 501         strbuf_addf(&script_snippet,
 502                     ". git-sh-setup && . git-rebase--common &&"
 503                     " . %s && %s", backend, backend_func);
 504         argv[0] = script_snippet.buf;
 505
 506         status = run_command_v_opt(argv, RUN_USING_SHELL);
 507 finished_rebase:
 508         if (opts->dont_finish_rebase)
 509                 ; /* do nothing */
 510         else if (opts->type == REBASE_INTERACTIVE)
 511                 ; /* interactive rebase cleans up after itself */
 512         else if (status == 0) {
 513                 if (!file_exists(state_dir_path("stopped-sha", opts)))
 514                         finish_rebase(opts);
 515         } else if (status == 2) {
 516                 struct strbuf dir = STRBUF_INIT;
 517
 518                 apply_autostash(opts);
 519                 strbuf_addstr(&dir, opts->state_dir);
 520                 remove_dir_recursively(&dir, 0);
 521                 strbuf_release(&dir);
 522                 die("Nothing to do");
 523         }
 524
 525         strbuf_release(&script_snippet);
 526
 527         return status ? -1 : 0;
 528 }
 529
 530 #define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
 531
 532 #define RESET_HEAD_DETACH (1<<0)
 533 #define RESET_HEAD_HARD (1<<1)
 534
 535 static int reset_head(struct object_id *oid, const char *action,
 536                       const char *switch_to_branch, unsigned flags,
 537                       const char *reflog_orig_head, const char *reflog_head)
 538 {
 539         unsigned detach_head = flags & RESET_HEAD_DETACH;
 540         unsigned reset_hard = flags & RESET_HEAD_HARD;
 541         struct object_id head_oid;
 542         struct tree_desc desc[2] = { { NULL }, { NULL } };
 543         struct lock_file lock = LOCK_INIT;
 544         struct unpack_trees_options unpack_tree_opts;
 545         struct tree *tree;
 546         const char *reflog_action;
 547         struct strbuf msg = STRBUF_INIT;
 548         size_t prefix_len;
 549         struct object_id *orig = NULL, oid_orig,
 550                 *old_orig = NULL, oid_old_orig;
 551         int ret = 0, nr = 0;
 552
 553         if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
 554                 BUG("Not a fully qualified branch: '%s'", switch_to_branch);
 555
 556         if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0) {
 557                 ret = -1;
 558                 goto leave_reset_head;
 559         }
 560
 561         if ((!oid || !reset_hard) && get_oid("HEAD", &head_oid)) {
 562                 ret = error(_("could not determine HEAD revision"));
 563                 goto leave_reset_head;
 564         }
 565
 566         if (!oid)
 567                 oid = &head_oid;
 568
 569         memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
 570         setup_unpack_trees_porcelain(&unpack_tree_opts, action);
 571         unpack_tree_opts.head_idx = 1;
 572         unpack_tree_opts.src_index = the_repository->index;
 573         unpack_tree_opts.dst_index = the_repository->index;
 574         unpack_tree_opts.fn = reset_hard ? oneway_merge : twoway_merge;
 575         unpack_tree_opts.update = 1;
 576         unpack_tree_opts.merge = 1;
 577         if (!detach_head)
 578                 unpack_tree_opts.reset = 1;
 579
 580         if (read_index_unmerged(the_repository->index) < 0) {
 581                 ret = error(_("could not read index"));
 582                 goto leave_reset_head;
 583         }
 584
 585         if (!reset_hard && !fill_tree_descriptor(&desc[nr++], &head_oid)) {
 586                 ret = error(_("failed to find tree of %s"),
 587                             oid_to_hex(&head_oid));
 588                 goto leave_reset_head;
 589         }
 590
 591         if (!fill_tree_descriptor(&desc[nr++], oid)) {
 592                 ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
 593                 goto leave_reset_head;
 594         }
 595
 596         if (unpack_trees(nr, desc, &unpack_tree_opts)) {
 597                 ret = -1;
 598                 goto leave_reset_head;
 599         }
 600
 601         tree = parse_tree_indirect(oid);
 602         prime_cache_tree(the_repository->index, tree);
 603
 604         if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0) {
 605                 ret = error(_("could not write index"));
 606                 goto leave_reset_head;
 607         }
 608
 609         reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
 610         strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
 611         prefix_len = msg.len;
 612
 613         if (!get_oid("ORIG_HEAD", &oid_old_orig))
 614                 old_orig = &oid_old_orig;
 615         if (!get_oid("HEAD", &oid_orig)) {
 616                 orig = &oid_orig;
 617                 if (!reflog_orig_head) {
 618                         strbuf_addstr(&msg, "updating ORIG_HEAD");
 619                         reflog_orig_head = msg.buf;
 620                 }
 621                 update_ref(reflog_orig_head, "ORIG_HEAD", orig, old_orig, 0,
 622                            UPDATE_REFS_MSG_ON_ERR);
 623         } else if (old_orig)
 624                 delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
 625         if (!reflog_head) {
 626                 strbuf_setlen(&msg, prefix_len);
 627                 strbuf_addstr(&msg, "updating HEAD");
 628                 reflog_head = msg.buf;
 629         }
 630         if (!switch_to_branch)
 631                 ret = update_ref(reflog_head, "HEAD", oid, orig,
 632                                  detach_head ? REF_NO_DEREF : 0,
 633                                  UPDATE_REFS_MSG_ON_ERR);
 634         else {
 635                 ret = create_symref("HEAD", switch_to_branch, msg.buf);
 636                 if (!ret)
 637                         ret = update_ref(reflog_head, "HEAD", oid, NULL, 0,
 638                                          UPDATE_REFS_MSG_ON_ERR);
 639         }
 640
 641 leave_reset_head:
 642         strbuf_release(&msg);
 643         rollback_lock_file(&lock);
 644         while (nr)
 645                 free((void *)desc[--nr].buffer);
 646         return ret;
 647 }
 648
 649 static int rebase_config(const char *var, const char *value, void *data)
 650 {
 651         struct rebase_options *opts = data;
 652
 653         if (!strcmp(var, "rebase.stat")) {
 654                 if (git_config_bool(var, value))
 655                         opts->flags |= REBASE_DIFFSTAT;
 656                 else
 657                         opts->flags &= !REBASE_DIFFSTAT;
 658                 return 0;
 659         }
 660
 661         if (!strcmp(var, "rebase.autosquash")) {
 662                 opts->autosquash = git_config_bool(var, value);
 663                 return 0;
 664         }
 665
 666         if (!strcmp(var, "commit.gpgsign")) {
 667                 free(opts->gpg_sign_opt);
 668                 opts->gpg_sign_opt = git_config_bool(var, value) ?
 669                         xstrdup("-S") : NULL;
 670                 return 0;
 671         }
 672
 673         if (!strcmp(var, "rebase.autostash")) {
 674                 opts->autostash = git_config_bool(var, value);
 675                 return 0;
 676         }
 677
 678         return git_default_config(var, value, data);
 679 }
 680
 681 /*
 682  * Determines whether the commits in from..to are linear, i.e. contain
 683  * no merge commits. This function *expects* `from` to be an ancestor of
 684  * `to`.
 685  */
 686 static int is_linear_history(struct commit *from, struct commit *to)
 687 {
 688         while (to && to != from) {
 689                 parse_commit(to);
 690                 if (!to->parents)
 691                         return 1;
 692                 if (to->parents->next)
 693                         return 0;
 694                 to = to->parents->item;
 695         }
 696         return 1;
 697 }
 698
 699 static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
 700                             struct object_id *merge_base)
 701 {
 702         struct commit *head = lookup_commit(the_repository, head_oid);
 703         struct commit_list *merge_bases;
 704         int res;
 705
 706         if (!head)
 707                 return 0;
 708
 709         merge_bases = get_merge_bases(onto, head);
 710         if (merge_bases && !merge_bases->next) {
 711                 oidcpy(merge_base, &merge_bases->item->object.oid);
 712                 res = oideq(merge_base, &onto->object.oid);
 713         } else {
 714                 oidcpy(merge_base, &null_oid);
 715                 res = 0;
 716         }
 717         free_commit_list(merge_bases);
 718         return res && is_linear_history(onto, head);
 719 }
 720
 721 /* -i followed by -m is still -i */
 722 static int parse_opt_merge(const struct option *opt, const char *arg, int unset)
 723 {
 724         struct rebase_options *opts = opt->value;
 725
 726         BUG_ON_OPT_NEG(unset);
 727         BUG_ON_OPT_ARG(arg);
 728
 729         if (!is_interactive(opts))
 730                 opts->type = REBASE_MERGE;
 731
 732         return 0;
 733 }
 734
 735 /* -i followed by -p is still explicitly interactive, but -p alone is not */
 736 static int parse_opt_interactive(const struct option *opt, const char *arg,
 737                                  int unset)
 738 {
 739         struct rebase_options *opts = opt->value;
 740
 741         BUG_ON_OPT_NEG(unset);
 742         BUG_ON_OPT_ARG(arg);
 743
 744         opts->type = REBASE_INTERACTIVE;
 745         opts->flags |= REBASE_INTERACTIVE_EXPLICIT;
 746
 747         return 0;
 748 }
 749
 750 static void NORETURN error_on_missing_default_upstream(void)
 751 {
 752         struct branch *current_branch = branch_get(NULL);
 753
 754         printf(_("%s\n"
 755                  "Please specify which branch you want to rebase against.\n"
 756                  "See git-rebase(1) for details.\n"
 757                  "\n"
 758                  "    git rebase '<branch>'\n"
 759                  "\n"),
 760                 current_branch ? _("There is no tracking information for "
 761                         "the current branch.") :
 762                         _("You are not currently on a branch."));
 763
 764         if (current_branch) {
 765                 const char *remote = current_branch->remote_name;
 766
 767                 if (!remote)
 768                         remote = _("<remote>");
 769
 770                 printf(_("If you wish to set tracking information for this "
 771                          "branch you can do so with:\n"
 772                          "\n"
 773                          "    git branch --set-upstream-to=%s/<branch> %s\n"
 774                          "\n"),
 775                        remote, current_branch->name);
 776         }
 777         exit(1);
 778 }
 779
 780 static void set_reflog_action(struct rebase_options *options)
 781 {
 782         const char *env;
 783         struct strbuf buf = STRBUF_INIT;
 784
 785         if (!is_interactive(options))
 786                 return;
 787
 788         env = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
 789         if (env && strcmp("rebase", env))
 790                 return; /* only override it if it is "rebase" */
 791
 792         strbuf_addf(&buf, "rebase -i (%s)", options->action);
 793         setenv(GIT_REFLOG_ACTION_ENVIRONMENT, buf.buf, 1);
 794         strbuf_release(&buf);
 795 }
 796
 797 int cmd_rebase(int argc, const char **argv, const char *prefix)
 798 {
 799         struct rebase_options options = {
 800                 .type = REBASE_UNSPECIFIED,
 801                 .flags = REBASE_NO_QUIET,
 802                 .git_am_opts = ARGV_ARRAY_INIT,
 803                 .allow_rerere_autoupdate  = -1,
 804                 .allow_empty_message = 1,
 805                 .git_format_patch_opt = STRBUF_INIT,
 806         };
 807         const char *branch_name;
 808         int ret, flags, total_argc, in_progress = 0;
 809         int ok_to_skip_pre_rebase = 0;
 810         struct strbuf msg = STRBUF_INIT;
 811         struct strbuf revisions = STRBUF_INIT;
 812         struct strbuf buf = STRBUF_INIT;
 813         struct object_id merge_base;
 814         enum {
 815                 NO_ACTION,
 816                 ACTION_CONTINUE,
 817                 ACTION_SKIP,
 818                 ACTION_ABORT,
 819                 ACTION_QUIT,
 820                 ACTION_EDIT_TODO,
 821                 ACTION_SHOW_CURRENT_PATCH,
 822         } action = NO_ACTION;
 823         const char *gpg_sign = NULL;
 824         struct string_list exec = STRING_LIST_INIT_NODUP;
 825         const char *rebase_merges = NULL;
 826         int fork_point = -1;
 827         struct string_list strategy_options = STRING_LIST_INIT_NODUP;
 828         struct object_id squash_onto;
 829         char *squash_onto_name = NULL;
 830         struct option builtin_rebase_options[] = {
 831                 OPT_STRING(0, "onto", &options.onto_name,
 832                            N_("revision"),
 833                            N_("rebase onto given branch instead of upstream")),
 834                 OPT_BOOL(0, "no-verify", &ok_to_skip_pre_rebase,
 835                          N_("allow pre-rebase hook to run")),
 836                 OPT_NEGBIT('q', "quiet", &options.flags,
 837                            N_("be quiet. implies --no-stat"),
 838                            REBASE_NO_QUIET| REBASE_VERBOSE | REBASE_DIFFSTAT),
 839                 OPT_BIT('v', "verbose", &options.flags,
 840                         N_("display a diffstat of what changed upstream"),
 841                         REBASE_NO_QUIET | REBASE_VERBOSE | REBASE_DIFFSTAT),
 842                 {OPTION_NEGBIT, 'n', "no-stat", &options.flags, NULL,
 843                         N_("do not show diffstat of what changed upstream"),
 844                         PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
 845                 OPT_BOOL(0, "signoff", &options.signoff,
 846                          N_("add a Signed-off-by: line to each commit")),
 847                 OPT_PASSTHRU_ARGV(0, "ignore-whitespace", &options.git_am_opts,
 848                                   NULL, N_("passed to 'git am'"),
 849                                   PARSE_OPT_NOARG),
 850                 OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
 851                                   &options.git_am_opts, NULL,
 852                                   N_("passed to 'git am'"), PARSE_OPT_NOARG),
 853                 OPT_PASSTHRU_ARGV(0, "ignore-date", &options.git_am_opts, NULL,
 854                                   N_("passed to 'git am'"), PARSE_OPT_NOARG),
 855                 OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
 856                                   N_("passed to 'git apply'"), 0),
 857                 OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
 858                                   N_("action"), N_("passed to 'git apply'"), 0),
 859                 OPT_BIT('f', "force-rebase", &options.flags,
 860                         N_("cherry-pick all commits, even if unchanged"),
 861                         REBASE_FORCE),
 862                 OPT_BIT(0, "no-ff", &options.flags,
 863                         N_("cherry-pick all commits, even if unchanged"),
 864                         REBASE_FORCE),
 865                 OPT_CMDMODE(0, "continue", &action, N_("continue"),
 866                             ACTION_CONTINUE),
 867                 OPT_CMDMODE(0, "skip", &action,
 868                             N_("skip current patch and continue"), ACTION_SKIP),
 869                 OPT_CMDMODE(0, "abort", &action,
 870                             N_("abort and check out the original branch"),
 871                             ACTION_ABORT),
 872                 OPT_CMDMODE(0, "quit", &action,
 873                             N_("abort but keep HEAD where it is"), ACTION_QUIT),
 874                 OPT_CMDMODE(0, "edit-todo", &action, N_("edit the todo list "
 875                             "during an interactive rebase"), ACTION_EDIT_TODO),
 876                 OPT_CMDMODE(0, "show-current-patch", &action,
 877                             N_("show the patch file being applied or merged"),
 878                             ACTION_SHOW_CURRENT_PATCH),
 879                 { OPTION_CALLBACK, 'm', "merge", &options, NULL,
 880                         N_("use merging strategies to rebase"),
 881                         PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 882                         parse_opt_merge },
 883                 { OPTION_CALLBACK, 'i', "interactive", &options, NULL,
 884                         N_("let the user edit the list of commits to rebase"),
 885                         PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 886                         parse_opt_interactive },
 887                 OPT_SET_INT('p', "preserve-merges", &options.type,
 888                             N_("try to recreate merges instead of ignoring "
 889                                "them"), REBASE_PRESERVE_MERGES),
 890                 OPT_BOOL(0, "rerere-autoupdate",
 891                          &options.allow_rerere_autoupdate,
 892                          N_("allow rerere to update index with resolved "
 893                             "conflict")),
 894                 OPT_BOOL('k', "keep-empty", &options.keep_empty,
 895                          N_("preserve empty commits during rebase")),
 896                 OPT_BOOL(0, "autosquash", &options.autosquash,
 897                          N_("move commits that begin with "
 898                             "squash!/fixup! under -i")),
 899                 { OPTION_STRING, 'S', "gpg-sign", &gpg_sign, N_("key-id"),
 900                         N_("GPG-sign commits"),
 901                         PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 902                 OPT_BOOL(0, "autostash", &options.autostash,
 903                          N_("automatically stash/stash pop before and after")),
 904                 OPT_STRING_LIST('x', "exec", &exec, N_("exec"),
 905                                 N_("add exec lines after each commit of the "
 906                                    "editable list")),
 907                 OPT_BOOL(0, "allow-empty-message",
 908                          &options.allow_empty_message,
 909                          N_("allow rebasing commits with empty messages")),
 910                 {OPTION_STRING, 'r', "rebase-merges", &rebase_merges,
 911                         N_("mode"),
 912                         N_("try to rebase merges instead of skipping them"),
 913                         PARSE_OPT_OPTARG, NULL, (intptr_t)""},
 914                 OPT_BOOL(0, "fork-point", &fork_point,
 915                          N_("use 'merge-base --fork-point' to refine upstream")),
 916                 OPT_STRING('s', "strategy", &options.strategy,
 917                            N_("strategy"), N_("use the given merge strategy")),
 918                 OPT_STRING_LIST('X', "strategy-option", &strategy_options,
 919                                 N_("option"),
 920                                 N_("pass the argument through to the merge "
 921                                    "strategy")),
 922                 OPT_BOOL(0, "root", &options.root,
 923                          N_("rebase all reachable commits up to the root(s)")),
 924                 OPT_END(),
 925         };
 926         int i;
 927
 928         /*
 929          * NEEDSWORK: Once the builtin rebase has been tested enough
 930          * and git-legacy-rebase.sh is retired to contrib/, this preamble
 931          * can be removed.
 932          */
 933
 934         if (!use_builtin_rebase()) {
 935                 const char *path = mkpath("%s/git-legacy-rebase",
 936                                           git_exec_path());
 937
 938                 if (sane_execvp(path, (char **)argv) < 0)
 939                         die_errno(_("could not exec %s"), path);
 940                 else
 941                         BUG("sane_execvp() returned???");
 942         }
 943
 944         if (argc == 2 && !strcmp(argv[1], "-h"))
 945                 usage_with_options(builtin_rebase_usage,
 946                                    builtin_rebase_options);
 947
 948         prefix = setup_git_directory();
 949         trace_repo_setup(prefix);
 950         setup_work_tree();
 951
 952         git_config(rebase_config, &options);
 953
 954         strbuf_reset(&buf);
 955         strbuf_addf(&buf, "%s/applying", apply_dir());
 956         if(file_exists(buf.buf))
 957                 die(_("It looks like 'git am' is in progress. Cannot rebase."));
 958
 959         if (is_directory(apply_dir())) {
 960                 options.type = REBASE_AM;
 961                 options.state_dir = apply_dir();
 962         } else if (is_directory(merge_dir())) {
 963                 strbuf_reset(&buf);
 964                 strbuf_addf(&buf, "%s/rewritten", merge_dir());
 965                 if (is_directory(buf.buf)) {
 966                         options.type = REBASE_PRESERVE_MERGES;
 967                         options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 968                 } else {
 969                         strbuf_reset(&buf);
 970                         strbuf_addf(&buf, "%s/interactive", merge_dir());
 971                         if(file_exists(buf.buf)) {
 972                                 options.type = REBASE_INTERACTIVE;
 973                                 options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 974                         } else
 975                                 options.type = REBASE_MERGE;
 976                 }
 977                 options.state_dir = merge_dir();
 978         }
 979
 980         if (options.type != REBASE_UNSPECIFIED)
 981                 in_progress = 1;
 982
 983         total_argc = argc;
 984         argc = parse_options(argc, argv, prefix,
 985                              builtin_rebase_options,
 986                              builtin_rebase_usage, 0);
 987
 988         if (action != NO_ACTION && total_argc != 2) {
 989                 usage_with_options(builtin_rebase_usage,
 990                                    builtin_rebase_options);
 991         }
 992
 993         if (argc > 2)
 994                 usage_with_options(builtin_rebase_usage,
 995                                    builtin_rebase_options);
 996
 997         if (action != NO_ACTION && !in_progress)
 998                 die(_("No rebase in progress?"));
 999         setenv(GIT_REFLOG_ACTION_ENVIRONMENT, "rebase", 0);
1000
1001         if (action == ACTION_EDIT_TODO && !is_interactive(&options))
1002                 die(_("The --edit-todo action can only be used during "
1003                       "interactive rebase."));
1004
1005         switch (action) {
1006         case ACTION_CONTINUE: {
1007                 struct object_id head;
1008                 struct lock_file lock_file = LOCK_INIT;
1009                 int fd;
1010
1011                 options.action = "continue";
1012                 set_reflog_action(&options);
1013
1014                 /* Sanity check */
1015                 if (get_oid("HEAD", &head))
1016                         die(_("Cannot read HEAD"));
1017
1018                 fd = hold_locked_index(&lock_file, 0);
1019                 if (read_index(the_repository->index) < 0)
1020                         die(_("could not read index"));
1021                 refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL,
1022                               NULL);
1023                 if (0 <= fd)
1024                         update_index_if_able(the_repository->index,
1025                                              &lock_file);
1026                 rollback_lock_file(&lock_file);
1027
1028                 if (has_unstaged_changes(1)) {
1029                         puts(_("You must edit all merge conflicts and then\n"
1030                                "mark them as resolved using git add"));
1031                         exit(1);
1032                 }
1033                 if (read_basic_state(&options))
1034                         exit(1);
1035                 goto run_rebase;
1036         }
1037         case ACTION_SKIP: {
1038                 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1039
1040                 options.action = "skip";
1041                 set_reflog_action(&options);
1042
1043                 rerere_clear(&merge_rr);
1044                 string_list_clear(&merge_rr, 1);
1045
1046                 if (reset_head(NULL, "reset", NULL, RESET_HEAD_HARD,
1047                                NULL, NULL) < 0)
1048                         die(_("could not discard worktree changes"));
1049                 remove_branch_state();
1050                 if (read_basic_state(&options))
1051                         exit(1);
1052                 goto run_rebase;
1053         }
1054         case ACTION_ABORT: {
1055                 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1056                 options.action = "abort";
1057                 set_reflog_action(&options);
1058
1059                 rerere_clear(&merge_rr);
1060                 string_list_clear(&merge_rr, 1);
1061
1062                 if (read_basic_state(&options))
1063                         exit(1);
1064                 if (reset_head(&options.orig_head, "reset",
1065                                options.head_name, RESET_HEAD_HARD,
1066                                NULL, NULL) < 0)
1067                         die(_("could not move back to %s"),
1068                             oid_to_hex(&options.orig_head));
1069                 remove_branch_state();
1070                 ret = finish_rebase(&options);
1071                 goto cleanup;
1072         }
1073         case ACTION_QUIT: {
1074                 strbuf_reset(&buf);
1075                 strbuf_addstr(&buf, options.state_dir);
1076                 ret = !!remove_dir_recursively(&buf, 0);
1077                 if (ret)
1078                         die(_("could not remove '%s'"), options.state_dir);
1079                 goto cleanup;
1080         }
1081         case ACTION_EDIT_TODO:
1082                 options.action = "edit-todo";
1083                 options.dont_finish_rebase = 1;
1084                 goto run_rebase;
1085         case ACTION_SHOW_CURRENT_PATCH:
1086                 options.action = "show-current-patch";
1087                 options.dont_finish_rebase = 1;
1088                 goto run_rebase;
1089         case NO_ACTION:
1090                 break;
1091         default:
1092                 BUG("action: %d", action);
1093         }
1094
1095         /* Make sure no rebase is in progress */
1096         if (in_progress) {
1097                 const char *last_slash = strrchr(options.state_dir, '/');
1098                 const char *state_dir_base =
1099                         last_slash ? last_slash + 1 : options.state_dir;
1100                 const char *cmd_live_rebase =
1101                         "git rebase (--continue | --abort | --skip)";
1102                 strbuf_reset(&buf);
1103                 strbuf_addf(&buf, "rm -fr \"%s\"", options.state_dir);
1104                 die(_("It seems that there is already a %s directory, and\n"
1105                       "I wonder if you are in the middle of another rebase.  "
1106                       "If that is the\n"
1107                       "case, please try\n\t%s\n"
1108                       "If that is not the case, please\n\t%s\n"
1109                       "and run me again.  I am stopping in case you still "
1110                       "have something\n"
1111                       "valuable there.\n"),
1112                     state_dir_base, cmd_live_rebase, buf.buf);
1113         }
1114
1115         for (i = 0; i < options.git_am_opts.argc; i++) {
1116                 const char *option = options.git_am_opts.argv[i], *p;
1117                 if (!strcmp(option, "--committer-date-is-author-date") ||
1118                     !strcmp(option, "--ignore-date") ||
1119                     !strcmp(option, "--whitespace=fix") ||
1120                     !strcmp(option, "--whitespace=strip"))
1121                         options.flags |= REBASE_FORCE;
1122                 else if (skip_prefix(option, "-C", &p)) {
1123                         while (*p)
1124                                 if (!isdigit(*(p++)))
1125                                         die(_("switch `C' expects a "
1126                                               "numerical value"));
1127                 } else if (skip_prefix(option, "--whitespace=", &p)) {
1128                         if (*p && strcmp(p, "warn") && strcmp(p, "nowarn") &&
1129                             strcmp(p, "error") && strcmp(p, "error-all"))
1130                                 die("Invalid whitespace option: '%s'", p);
1131                 }
1132         }
1133
1134         if (!(options.flags & REBASE_NO_QUIET))
1135                 argv_array_push(&options.git_am_opts, "-q");
1136
1137         if (options.keep_empty)
1138                 imply_interactive(&options, "--keep-empty");
1139
1140         if (gpg_sign) {
1141                 free(options.gpg_sign_opt);
1142                 options.gpg_sign_opt = xstrfmt("-S%s", gpg_sign);
1143         }
1144
1145         if (exec.nr) {
1146                 int i;
1147
1148                 imply_interactive(&options, "--exec");
1149
1150                 strbuf_reset(&buf);
1151                 for (i = 0; i < exec.nr; i++)
1152                         strbuf_addf(&buf, "exec %s\n", exec.items[i].string);
1153                 options.cmd = xstrdup(buf.buf);
1154         }
1155
1156         if (rebase_merges) {
1157                 if (!*rebase_merges)
1158                         ; /* default mode; do nothing */
1159                 else if (!strcmp("rebase-cousins", rebase_merges))
1160                         options.rebase_cousins = 1;
1161                 else if (strcmp("no-rebase-cousins", rebase_merges))
1162                         die(_("Unknown mode: %s"), rebase_merges);
1163                 options.rebase_merges = 1;
1164                 imply_interactive(&options, "--rebase-merges");
1165         }
1166
1167         if (strategy_options.nr) {
1168                 int i;
1169
1170                 if (!options.strategy)
1171                         options.strategy = "recursive";
1172
1173                 strbuf_reset(&buf);
1174                 for (i = 0; i < strategy_options.nr; i++)
1175                         strbuf_addf(&buf, " --%s",
1176                                     strategy_options.items[i].string);
1177                 options.strategy_opts = xstrdup(buf.buf);
1178         }
1179
1180         if (options.strategy) {
1181                 options.strategy = xstrdup(options.strategy);
1182                 switch (options.type) {
1183                 case REBASE_AM:
1184                         die(_("--strategy requires --merge or --interactive"));
1185                 case REBASE_MERGE:
1186                 case REBASE_INTERACTIVE:
1187                 case REBASE_PRESERVE_MERGES:
1188                         /* compatible */
1189                         break;
1190                 case REBASE_UNSPECIFIED:
1191                         options.type = REBASE_MERGE;
1192                         break;
1193                 default:
1194                         BUG("unhandled rebase type (%d)", options.type);
1195                 }
1196         }
1197
1198         if (options.root && !options.onto_name)
1199                 imply_interactive(&options, "--root without --onto");
1200
1201         if (isatty(2) && options.flags & REBASE_NO_QUIET)
1202                 strbuf_addstr(&options.git_format_patch_opt, " --progress");
1203
1204         switch (options.type) {
1205         case REBASE_MERGE:
1206         case REBASE_INTERACTIVE:
1207         case REBASE_PRESERVE_MERGES:
1208                 options.state_dir = merge_dir();
1209                 break;
1210         case REBASE_AM:
1211                 options.state_dir = apply_dir();
1212                 break;
1213         default:
1214                 /* the default rebase backend is `--am` */
1215                 options.type = REBASE_AM;
1216                 options.state_dir = apply_dir();
1217                 break;
1218         }
1219
1220         if (options.git_am_opts.argc) {
1221                 /* all am options except -q are compatible only with --am */
1222                 for (i = options.git_am_opts.argc - 1; i >= 0; i--)
1223                         if (strcmp(options.git_am_opts.argv[i], "-q"))
1224                                 break;
1225
1226                 if (is_interactive(&options) && i >= 0)
1227                         die(_("error: cannot combine interactive options "
1228                               "(--interactive, --exec, --rebase-merges, "
1229                               "--preserve-merges, --keep-empty, --root + "
1230                               "--onto) with am options (%s)"), buf.buf);
1231                 if (options.type == REBASE_MERGE && i >= 0)
1232                         die(_("error: cannot combine merge options (--merge, "
1233                               "--strategy, --strategy-option) with am options "
1234                               "(%s)"), buf.buf);
1235         }
1236
1237         if (options.signoff) {
1238                 if (options.type == REBASE_PRESERVE_MERGES)
1239                         die("cannot combine '--signoff' with "
1240                             "'--preserve-merges'");
1241                 argv_array_push(&options.git_am_opts, "--signoff");
1242                 options.flags |= REBASE_FORCE;
1243         }
1244
1245         if (options.type == REBASE_PRESERVE_MERGES)
1246                 /*
1247                  * Note: incompatibility with --signoff handled in signoff block above
1248                  * Note: incompatibility with --interactive is just a strong warning;
1249                  *       git-rebase.txt caveats with "unless you know what you are doing"
1250                  */
1251                 if (options.rebase_merges)
1252                         die(_("error: cannot combine '--preserve-merges' with "
1253                               "'--rebase-merges'"));
1254
1255         if (options.rebase_merges) {
1256                 if (strategy_options.nr)
1257                         die(_("error: cannot combine '--rebase-merges' with "
1258                               "'--strategy-option'"));
1259                 if (options.strategy)
1260                         die(_("error: cannot combine '--rebase-merges' with "
1261                               "'--strategy'"));
1262         }
1263
1264         if (!options.root) {
1265                 if (argc < 1) {
1266                         struct branch *branch;
1267
1268                         branch = branch_get(NULL);
1269                         options.upstream_name = branch_get_upstream(branch,
1270                                                                     NULL);
1271                         if (!options.upstream_name)
1272                                 error_on_missing_default_upstream();
1273                         if (fork_point < 0)
1274                                 fork_point = 1;
1275                 } else {
1276                         options.upstream_name = argv[0];
1277                         argc--;
1278                         argv++;
1279                         if (!strcmp(options.upstream_name, "-"))
1280                                 options.upstream_name = "@{-1}";
1281                 }
1282                 options.upstream = peel_committish(options.upstream_name);
1283                 if (!options.upstream)
1284                         die(_("invalid upstream '%s'"), options.upstream_name);
1285                 options.upstream_arg = options.upstream_name;
1286         } else {
1287                 if (!options.onto_name) {
1288                         if (commit_tree("", 0, the_hash_algo->empty_tree, NULL,
1289                                         &squash_onto, NULL, NULL) < 0)
1290                                 die(_("Could not create new root commit"));
1291                         options.squash_onto = &squash_onto;
1292                         options.onto_name = squash_onto_name =
1293                                 xstrdup(oid_to_hex(&squash_onto));
1294                 }
1295                 options.upstream_name = NULL;
1296                 options.upstream = NULL;
1297                 if (argc > 1)
1298                         usage_with_options(builtin_rebase_usage,
1299                                            builtin_rebase_options);
1300                 options.upstream_arg = "--root";
1301         }
1302
1303         /* Make sure the branch to rebase onto is valid. */
1304         if (!options.onto_name)
1305                 options.onto_name = options.upstream_name;
1306         if (strstr(options.onto_name, "...")) {
1307                 if (get_oid_mb(options.onto_name, &merge_base) < 0)
1308                         die(_("'%s': need exactly one merge base"),
1309                             options.onto_name);
1310                 options.onto = lookup_commit_or_die(&merge_base,
1311                                                     options.onto_name);
1312         } else {
1313                 options.onto = peel_committish(options.onto_name);
1314                 if (!options.onto)
1315                         die(_("Does not point to a valid commit '%s'"),
1316                                 options.onto_name);
1317         }
1318
1319         /*
1320          * If the branch to rebase is given, that is the branch we will rebase
1321          * branch_name -- branch/commit being rebased, or
1322          *                HEAD (already detached)
1323          * orig_head -- commit object name of tip of the branch before rebasing
1324          * head_name -- refs/heads/<that-branch> or NULL (detached HEAD)
1325          */
1326         if (argc == 1) {
1327                 /* Is it "rebase other branchname" or "rebase other commit"? */
1328                 branch_name = argv[0];
1329                 options.switch_to = argv[0];
1330
1331                 /* Is it a local branch? */
1332                 strbuf_reset(&buf);
1333                 strbuf_addf(&buf, "refs/heads/%s", branch_name);
1334                 if (!read_ref(buf.buf, &options.orig_head))
1335                         options.head_name = xstrdup(buf.buf);
1336                 /* If not is it a valid ref (branch or commit)? */
1337                 else if (!get_oid(branch_name, &options.orig_head))
1338                         options.head_name = NULL;
1339                 else
1340                         die(_("fatal: no such branch/commit '%s'"),
1341                             branch_name);
1342         } else if (argc == 0) {
1343                 /* Do not need to switch branches, we are already on it. */
1344                 options.head_name =
1345                         xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
1346                                          &flags));
1347                 if (!options.head_name)
1348                         die(_("No such ref: %s"), "HEAD");
1349                 if (flags & REF_ISSYMREF) {
1350                         if (!skip_prefix(options.head_name,
1351                                          "refs/heads/", &branch_name))
1352                                 branch_name = options.head_name;
1353
1354                 } else {
1355                         free(options.head_name);
1356                         options.head_name = NULL;
1357                         branch_name = "HEAD";
1358                 }
1359                 if (get_oid("HEAD", &options.orig_head))
1360                         die(_("Could not resolve HEAD to a revision"));
1361         } else
1362                 BUG("unexpected number of arguments left to parse");
1363
1364         if (fork_point > 0) {
1365                 struct commit *head =
1366                         lookup_commit_reference(the_repository,
1367                                                 &options.orig_head);
1368                 options.restrict_revision =
1369                         get_fork_point(options.upstream_name, head);
1370         }
1371
1372         if (read_index(the_repository->index) < 0)
1373                 die(_("could not read index"));
1374
1375         if (options.autostash) {
1376                 struct lock_file lock_file = LOCK_INIT;
1377                 int fd;
1378
1379                 fd = hold_locked_index(&lock_file, 0);
1380                 refresh_cache(REFRESH_QUIET);
1381                 if (0 <= fd)
1382                         update_index_if_able(&the_index, &lock_file);
1383                 rollback_lock_file(&lock_file);
1384
1385                 if (has_unstaged_changes(1) || has_uncommitted_changes(1)) {
1386                         const char *autostash =
1387                                 state_dir_path("autostash", &options);
1388                         struct child_process stash = CHILD_PROCESS_INIT;
1389                         struct object_id oid;
1390                         struct commit *head =
1391                                 lookup_commit_reference(the_repository,
1392                                                         &options.orig_head);
1393
1394                         argv_array_pushl(&stash.args,
1395                                          "stash", "create", "autostash", NULL);
1396                         stash.git_cmd = 1;
1397                         stash.no_stdin = 1;
1398                         strbuf_reset(&buf);
1399                         if (capture_command(&stash, &buf, GIT_MAX_HEXSZ))
1400                                 die(_("Cannot autostash"));
1401                         strbuf_trim_trailing_newline(&buf);
1402                         if (get_oid(buf.buf, &oid))
1403                                 die(_("Unexpected stash response: '%s'"),
1404                                     buf.buf);
1405                         strbuf_reset(&buf);
1406                         strbuf_add_unique_abbrev(&buf, &oid, DEFAULT_ABBREV);
1407
1408                         if (safe_create_leading_directories_const(autostash))
1409                                 die(_("Could not create directory for '%s'"),
1410                                     options.state_dir);
1411                         write_file(autostash, "%s", oid_to_hex(&oid));
1412                         printf(_("Created autostash: %s\n"), buf.buf);
1413                         if (reset_head(&head->object.oid, "reset --hard",
1414                                        NULL, RESET_HEAD_HARD, NULL, NULL) < 0)
1415                                 die(_("could not reset --hard"));
1416                         printf(_("HEAD is now at %s"),
1417                                find_unique_abbrev(&head->object.oid,
1418                                                   DEFAULT_ABBREV));
1419                         strbuf_reset(&buf);
1420                         pp_commit_easy(CMIT_FMT_ONELINE, head, &buf);
1421                         if (buf.len > 0)
1422                                 printf(" %s", buf.buf);
1423                         putchar('\n');
1424
1425                         if (discard_index(the_repository->index) < 0 ||
1426                                 read_index(the_repository->index) < 0)
1427                                 die(_("could not read index"));
1428                 }
1429         }
1430
1431         if (require_clean_work_tree("rebase",
1432                                     _("Please commit or stash them."), 1, 1)) {
1433                 ret = 1;
1434                 goto cleanup;
1435         }
1436
1437         /*
1438          * Now we are rebasing commits upstream..orig_head (or with --root,
1439          * everything leading up to orig_head) on top of onto.
1440          */
1441
1442         /*
1443          * Check if we are already based on onto with linear history,
1444          * but this should be done only when upstream and onto are the same
1445          * and if this is not an interactive rebase.
1446          */
1447         if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
1448             !is_interactive(&options) && !options.restrict_revision &&
1449             options.upstream &&
1450             !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
1451                 int flag;
1452
1453                 if (!(options.flags & REBASE_FORCE)) {
1454                         /* Lazily switch to the target branch if needed... */
1455                         if (options.switch_to) {
1456                                 struct object_id oid;
1457
1458                                 if (get_oid(options.switch_to, &oid) < 0) {
1459                                         ret = !!error(_("could not parse '%s'"),
1460                                                       options.switch_to);
1461                                         goto cleanup;
1462                                 }
1463
1464                                 strbuf_reset(&buf);
1465                                 strbuf_addf(&buf, "%s: checkout %s",
1466                                             getenv(GIT_REFLOG_ACTION_ENVIRONMENT),
1467                                             options.switch_to);
1468                                 if (reset_head(&oid, "checkout",
1469                                                options.head_name, 0,
1470                                                NULL, buf.buf) < 0) {
1471                                         ret = !!error(_("could not switch to "
1472                                                         "%s"),
1473                                                       options.switch_to);
1474                                         goto cleanup;
1475                                 }
1476                         }
1477
1478                         if (!(options.flags & REBASE_NO_QUIET))
1479                                 ; /* be quiet */
1480                         else if (!strcmp(branch_name, "HEAD") &&
1481                                  resolve_ref_unsafe("HEAD", 0, NULL, &flag))
1482                                 puts(_("HEAD is up to date."));
1483                         else
1484                                 printf(_("Current branch %s is up to date.\n"),
1485                                        branch_name);
1486                         ret = !!finish_rebase(&options);
1487                         goto cleanup;
1488                 } else if (!(options.flags & REBASE_NO_QUIET))
1489                         ; /* be quiet */
1490                 else if (!strcmp(branch_name, "HEAD") &&
1491                          resolve_ref_unsafe("HEAD", 0, NULL, &flag))
1492                         puts(_("HEAD is up to date, rebase forced."));
1493                 else
1494                         printf(_("Current branch %s is up to date, rebase "
1495                                  "forced.\n"), branch_name);
1496         }
1497
1498         /* If a hook exists, give it a chance to interrupt*/
1499         if (!ok_to_skip_pre_rebase &&
1500             run_hook_le(NULL, "pre-rebase", options.upstream_arg,
1501                         argc ? argv[0] : NULL, NULL))
1502                 die(_("The pre-rebase hook refused to rebase."));
1503
1504         if (options.flags & REBASE_DIFFSTAT) {
1505                 struct diff_options opts;
1506
1507                 if (options.flags & REBASE_VERBOSE) {
1508                         if (is_null_oid(&merge_base))
1509                                 printf(_("Changes to %s:\n"),
1510                                        oid_to_hex(&options.onto->object.oid));
1511                         else
1512                                 printf(_("Changes from %s to %s:\n"),
1513                                        oid_to_hex(&merge_base),
1514                                        oid_to_hex(&options.onto->object.oid));
1515                 }
1516
1517                 /* We want color (if set), but no pager */
1518                 diff_setup(&opts);
1519                 opts.stat_width = -1; /* use full terminal width */
1520                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
1521                 opts.output_format |=
1522                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
1523                 opts.detect_rename = DIFF_DETECT_RENAME;
1524                 diff_setup_done(&opts);
1525                 diff_tree_oid(is_null_oid(&merge_base) ?
1526                               the_hash_algo->empty_tree : &merge_base,
1527                               &options.onto->object.oid, "", &opts);
1528                 diffcore_std(&opts);
1529                 diff_flush(&opts);
1530         }
1531
1532         if (is_interactive(&options))
1533                 goto run_rebase;
1534
1535         /* Detach HEAD and reset the tree */
1536         if (options.flags & REBASE_NO_QUIET)
1537                 printf(_("First, rewinding head to replay your work on top of "
1538                          "it...\n"));
1539
1540         strbuf_addf(&msg, "%s: checkout %s",
1541                     getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
1542         if (reset_head(&options.onto->object.oid, "checkout", NULL,
1543                        RESET_HEAD_DETACH, NULL, msg.buf))
1544                 die(_("Could not detach HEAD"));
1545         strbuf_release(&msg);
1546
1547         /*
1548          * If the onto is a proper descendant of the tip of the branch, then
1549          * we just fast-forwarded.
1550          */
1551         strbuf_reset(&msg);
1552         if (!oidcmp(&merge_base, &options.orig_head)) {
1553                 printf(_("Fast-forwarded %s to %s.\n"),
1554                         branch_name, options.onto_name);
1555                 strbuf_addf(&msg, "rebase finished: %s onto %s",
1556                         options.head_name ? options.head_name : "detached HEAD",
1557                         oid_to_hex(&options.onto->object.oid));
1558                 reset_head(NULL, "Fast-forwarded", options.head_name, 0,
1559                            "HEAD", msg.buf);
1560                 strbuf_release(&msg);
1561                 ret = !!finish_rebase(&options);
1562                 goto cleanup;
1563         }
1564
1565         strbuf_addf(&revisions, "%s..%s",
1566                     options.root ? oid_to_hex(&options.onto->object.oid) :
1567                     (options.restrict_revision ?
1568                      oid_to_hex(&options.restrict_revision->object.oid) :
1569                      oid_to_hex(&options.upstream->object.oid)),
1570                     oid_to_hex(&options.orig_head));
1571
1572         options.revisions = revisions.buf;
1573
1574 run_rebase:
1575         ret = !!run_specific_rebase(&options);
1576
1577 cleanup:
1578         strbuf_release(&revisions);
1579         free(options.head_name);
1580         free(options.gpg_sign_opt);
1581         free(options.cmd);
1582         free(squash_onto_name);
1583         return ret;
1584 }