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         int reschedule_failed_exec;
 108 };
 109
 110 static int is_interactive(struct rebase_options *opts)
 111 {
 112         return opts->type == REBASE_INTERACTIVE ||
 113                 opts->type == REBASE_PRESERVE_MERGES;
 114 }
 115
 116 static void imply_interactive(struct rebase_options *opts, const char *option)
 117 {
 118         switch (opts->type) {
 119         case REBASE_AM:
 120                 die(_("%s requires an interactive rebase"), option);
 121                 break;
 122         case REBASE_INTERACTIVE:
 123         case REBASE_PRESERVE_MERGES:
 124                 break;
 125         case REBASE_MERGE:
 126                 /* we silently *upgrade* --merge to --interactive if needed */
 127         default:
 128                 opts->type = REBASE_INTERACTIVE; /* implied */
 129                 break;
 130         }
 131 }
 132
 133 /* Returns the filename prefixed by the state_dir */
 134 static const char *state_dir_path(const char *filename, struct rebase_options *opts)
 135 {
 136         static struct strbuf path = STRBUF_INIT;
 137         static size_t prefix_len;
 138
 139         if (!prefix_len) {
 140                 strbuf_addf(&path, "%s/", opts->state_dir);
 141                 prefix_len = path.len;
 142         }
 143
 144         strbuf_setlen(&path, prefix_len);
 145         strbuf_addstr(&path, filename);
 146         return path.buf;
 147 }
 148
 149 /* Read one file, then strip line endings */
 150 static int read_one(const char *path, struct strbuf *buf)
 151 {
 152         if (strbuf_read_file(buf, path, 0) < 0)
 153                 return error_errno(_("could not read '%s'"), path);
 154         strbuf_trim_trailing_newline(buf);
 155         return 0;
 156 }
 157
 158 /* Initialize the rebase options from the state directory. */
 159 static int read_basic_state(struct rebase_options *opts)
 160 {
 161         struct strbuf head_name = STRBUF_INIT;
 162         struct strbuf buf = STRBUF_INIT;
 163         struct object_id oid;
 164
 165         if (read_one(state_dir_path("head-name", opts), &head_name) ||
 166             read_one(state_dir_path("onto", opts), &buf))
 167                 return -1;
 168         opts->head_name = starts_with(head_name.buf, "refs/") ?
 169                 xstrdup(head_name.buf) : NULL;
 170         strbuf_release(&head_name);
 171         if (get_oid(buf.buf, &oid))
 172                 return error(_("could not get 'onto': '%s'"), buf.buf);
 173         opts->onto = lookup_commit_or_die(&oid, buf.buf);
 174
 175         /*
 176          * We always write to orig-head, but interactive rebase used to write to
 177          * head. Fall back to reading from head to cover for the case that the
 178          * user upgraded git with an ongoing interactive rebase.
 179          */
 180         strbuf_reset(&buf);
 181         if (file_exists(state_dir_path("orig-head", opts))) {
 182                 if (read_one(state_dir_path("orig-head", opts), &buf))
 183                         return -1;
 184         } else if (read_one(state_dir_path("head", opts), &buf))
 185                 return -1;
 186         if (get_oid(buf.buf, &opts->orig_head))
 187                 return error(_("invalid orig-head: '%s'"), buf.buf);
 188
 189         strbuf_reset(&buf);
 190         if (read_one(state_dir_path("quiet", opts), &buf))
 191                 return -1;
 192         if (buf.len)
 193                 opts->flags &= ~REBASE_NO_QUIET;
 194         else
 195                 opts->flags |= REBASE_NO_QUIET;
 196
 197         if (file_exists(state_dir_path("verbose", opts)))
 198                 opts->flags |= REBASE_VERBOSE;
 199
 200         if (file_exists(state_dir_path("signoff", opts))) {
 201                 opts->signoff = 1;
 202                 opts->flags |= REBASE_FORCE;
 203         }
 204
 205         if (file_exists(state_dir_path("allow_rerere_autoupdate", opts))) {
 206                 strbuf_reset(&buf);
 207                 if (read_one(state_dir_path("allow_rerere_autoupdate", opts),
 208                             &buf))
 209                         return -1;
 210                 if (!strcmp(buf.buf, "--rerere-autoupdate"))
 211                         opts->allow_rerere_autoupdate = 1;
 212                 else if (!strcmp(buf.buf, "--no-rerere-autoupdate"))
 213                         opts->allow_rerere_autoupdate = 0;
 214                 else
 215                         warning(_("ignoring invalid allow_rerere_autoupdate: "
 216                                   "'%s'"), buf.buf);
 217         } else
 218                 opts->allow_rerere_autoupdate = -1;
 219
 220         if (file_exists(state_dir_path("gpg_sign_opt", opts))) {
 221                 strbuf_reset(&buf);
 222                 if (read_one(state_dir_path("gpg_sign_opt", opts),
 223                             &buf))
 224                         return -1;
 225                 free(opts->gpg_sign_opt);
 226                 opts->gpg_sign_opt = xstrdup(buf.buf);
 227         }
 228
 229         if (file_exists(state_dir_path("strategy", opts))) {
 230                 strbuf_reset(&buf);
 231                 if (read_one(state_dir_path("strategy", opts), &buf))
 232                         return -1;
 233                 free(opts->strategy);
 234                 opts->strategy = xstrdup(buf.buf);
 235         }
 236
 237         if (file_exists(state_dir_path("strategy_opts", opts))) {
 238                 strbuf_reset(&buf);
 239                 if (read_one(state_dir_path("strategy_opts", opts), &buf))
 240                         return -1;
 241                 free(opts->strategy_opts);
 242                 opts->strategy_opts = xstrdup(buf.buf);
 243         }
 244
 245         strbuf_release(&buf);
 246
 247         return 0;
 248 }
 249
 250 static int apply_autostash(struct rebase_options *opts)
 251 {
 252         const char *path = state_dir_path("autostash", opts);
 253         struct strbuf autostash = STRBUF_INIT;
 254         struct child_process stash_apply = CHILD_PROCESS_INIT;
 255
 256         if (!file_exists(path))
 257                 return 0;
 258
 259         if (read_one(path, &autostash))
 260                 return error(_("Could not read '%s'"), path);
 261         /* Ensure that the hash is not mistaken for a number */
 262         strbuf_addstr(&autostash, "^0");
 263         argv_array_pushl(&stash_apply.args,
 264                          "stash", "apply", autostash.buf, NULL);
 265         stash_apply.git_cmd = 1;
 266         stash_apply.no_stderr = stash_apply.no_stdout =
 267                 stash_apply.no_stdin = 1;
 268         if (!run_command(&stash_apply))
 269                 printf(_("Applied autostash.\n"));
 270         else {
 271                 struct argv_array args = ARGV_ARRAY_INIT;
 272                 int res = 0;
 273
 274                 argv_array_pushl(&args,
 275                                  "stash", "store", "-m", "autostash", "-q",
 276                                  autostash.buf, NULL);
 277                 if (run_command_v_opt(args.argv, RUN_GIT_CMD))
 278                         res = error(_("Cannot store %s"), autostash.buf);
 279                 argv_array_clear(&args);
 280                 strbuf_release(&autostash);
 281                 if (res)
 282                         return res;
 283
 284                 fprintf(stderr,
 285                         _("Applying autostash resulted in conflicts.\n"
 286                           "Your changes are safe in the stash.\n"
 287                           "You can run \"git stash pop\" or \"git stash drop\" "
 288                           "at any time.\n"));
 289         }
 290
 291         strbuf_release(&autostash);
 292         return 0;
 293 }
 294
 295 static int finish_rebase(struct rebase_options *opts)
 296 {
 297         struct strbuf dir = STRBUF_INIT;
 298         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 299
 300         delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 301         apply_autostash(opts);
 302         close_all_packs(the_repository->objects);
 303         /*
 304          * We ignore errors in 'gc --auto', since the
 305          * user should see them.
 306          */
 307         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 308         strbuf_addstr(&dir, opts->state_dir);
 309         remove_dir_recursively(&dir, 0);
 310         strbuf_release(&dir);
 311
 312         return 0;
 313 }
 314
 315 static struct commit *peel_committish(const char *name)
 316 {
 317         struct object *obj;
 318         struct object_id oid;
 319
 320         if (get_oid(name, &oid))
 321                 return NULL;
 322         obj = parse_object(the_repository, &oid);
 323         return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
 324 }
 325
 326 static void add_var(struct strbuf *buf, const char *name, const char *value)
 327 {
 328         if (!value)
 329                 strbuf_addf(buf, "unset %s; ", name);
 330         else {
 331                 strbuf_addf(buf, "%s=", name);
 332                 sq_quote_buf(buf, value);
 333                 strbuf_addstr(buf, "; ");
 334         }
 335 }
 336
 337 static const char *resolvemsg =
 338 N_("Resolve all conflicts manually, mark them as resolved with\n"
 339 "\"git add/rm <conflicted_files>\", then run \"git rebase --continue\".\n"
 340 "You can instead skip this commit: run \"git rebase --skip\".\n"
 341 "To abort and get back to the state before \"git rebase\", run "
 342 "\"git rebase --abort\".");
 343
 344 static int run_specific_rebase(struct rebase_options *opts)
 345 {
 346         const char *argv[] = { NULL, NULL };
 347         struct strbuf script_snippet = STRBUF_INIT, buf = STRBUF_INIT;
 348         int status;
 349         const char *backend, *backend_func;
 350
 351         if (opts->type == REBASE_INTERACTIVE) {
 352                 /* Run builtin interactive rebase */
 353                 struct child_process child = CHILD_PROCESS_INIT;
 354
 355                 argv_array_pushf(&child.env_array, "GIT_CHERRY_PICK_HELP=%s",
 356                                  resolvemsg);
 357                 if (!(opts->flags & REBASE_INTERACTIVE_EXPLICIT)) {
 358                         argv_array_push(&child.env_array, "GIT_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                 if (opts->reschedule_failed_exec)
 420                         argv_array_push(&child.args, "--reschedule-failed-exec");
 421
 422                 status = run_command(&child);
 423                 goto finished_rebase;
 424         }
 425
 426         add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
 427         add_var(&script_snippet, "state_dir", opts->state_dir);
 428
 429         add_var(&script_snippet, "upstream_name", opts->upstream_name);
 430         add_var(&script_snippet, "upstream", opts->upstream ?
 431                 oid_to_hex(&opts->upstream->object.oid) : NULL);
 432         add_var(&script_snippet, "head_name",
 433                 opts->head_name ? opts->head_name : "detached HEAD");
 434         add_var(&script_snippet, "orig_head", oid_to_hex(&opts->orig_head));
 435         add_var(&script_snippet, "onto", opts->onto ?
 436                 oid_to_hex(&opts->onto->object.oid) : NULL);
 437         add_var(&script_snippet, "onto_name", opts->onto_name);
 438         add_var(&script_snippet, "revisions", opts->revisions);
 439         add_var(&script_snippet, "restrict_revision", opts->restrict_revision ?
 440                 oid_to_hex(&opts->restrict_revision->object.oid) : NULL);
 441         add_var(&script_snippet, "GIT_QUIET",
 442                 opts->flags & REBASE_NO_QUIET ? "" : "t");
 443         sq_quote_argv_pretty(&buf, opts->git_am_opts.argv);
 444         add_var(&script_snippet, "git_am_opt", buf.buf);
 445         strbuf_release(&buf);
 446         add_var(&script_snippet, "verbose",
 447                 opts->flags & REBASE_VERBOSE ? "t" : "");
 448         add_var(&script_snippet, "diffstat",
 449                 opts->flags & REBASE_DIFFSTAT ? "t" : "");
 450         add_var(&script_snippet, "force_rebase",
 451                 opts->flags & REBASE_FORCE ? "t" : "");
 452         if (opts->switch_to)
 453                 add_var(&script_snippet, "switch_to", opts->switch_to);
 454         add_var(&script_snippet, "action", opts->action ? opts->action : "");
 455         add_var(&script_snippet, "signoff", opts->signoff ? "--signoff" : "");
 456         add_var(&script_snippet, "allow_rerere_autoupdate",
 457                 opts->allow_rerere_autoupdate < 0 ? "" :
 458                 opts->allow_rerere_autoupdate ?
 459                 "--rerere-autoupdate" : "--no-rerere-autoupdate");
 460         add_var(&script_snippet, "keep_empty", opts->keep_empty ? "yes" : "");
 461         add_var(&script_snippet, "autosquash", opts->autosquash ? "t" : "");
 462         add_var(&script_snippet, "gpg_sign_opt", opts->gpg_sign_opt);
 463         add_var(&script_snippet, "cmd", opts->cmd);
 464         add_var(&script_snippet, "allow_empty_message",
 465                 opts->allow_empty_message ?  "--allow-empty-message" : "");
 466         add_var(&script_snippet, "rebase_merges",
 467                 opts->rebase_merges ? "t" : "");
 468         add_var(&script_snippet, "rebase_cousins",
 469                 opts->rebase_cousins ? "t" : "");
 470         add_var(&script_snippet, "strategy", opts->strategy);
 471         add_var(&script_snippet, "strategy_opts", opts->strategy_opts);
 472         add_var(&script_snippet, "rebase_root", opts->root ? "t" : "");
 473         add_var(&script_snippet, "squash_onto",
 474                 opts->squash_onto ? oid_to_hex(opts->squash_onto) : "");
 475         add_var(&script_snippet, "git_format_patch_opt",
 476                 opts->git_format_patch_opt.buf);
 477
 478         if (is_interactive(opts) &&
 479             !(opts->flags & REBASE_INTERACTIVE_EXPLICIT)) {
 480                 strbuf_addstr(&script_snippet,
 481                               "GIT_EDITOR=:; export GIT_EDITOR; ");
 482                 opts->autosquash = 0;
 483         }
 484
 485         switch (opts->type) {
 486         case REBASE_AM:
 487                 backend = "git-rebase--am";
 488                 backend_func = "git_rebase__am";
 489                 break;
 490         case REBASE_MERGE:
 491                 backend = "git-rebase--merge";
 492                 backend_func = "git_rebase__merge";
 493                 break;
 494         case REBASE_PRESERVE_MERGES:
 495                 backend = "git-rebase--preserve-merges";
 496                 backend_func = "git_rebase__preserve_merges";
 497                 break;
 498         default:
 499                 BUG("Unhandled rebase type %d", opts->type);
 500                 break;
 501         }
 502
 503         strbuf_addf(&script_snippet,
 504                     ". git-sh-setup && . git-rebase--common &&"
 505                     " . %s && %s", backend, backend_func);
 506         argv[0] = script_snippet.buf;
 507
 508         status = run_command_v_opt(argv, RUN_USING_SHELL);
 509 finished_rebase:
 510         if (opts->dont_finish_rebase)
 511                 ; /* do nothing */
 512         else if (opts->type == REBASE_INTERACTIVE)
 513                 ; /* interactive rebase cleans up after itself */
 514         else if (status == 0) {
 515                 if (!file_exists(state_dir_path("stopped-sha", opts)))
 516                         finish_rebase(opts);
 517         } else if (status == 2) {
 518                 struct strbuf dir = STRBUF_INIT;
 519
 520                 apply_autostash(opts);
 521                 strbuf_addstr(&dir, opts->state_dir);
 522                 remove_dir_recursively(&dir, 0);
 523                 strbuf_release(&dir);
 524                 die("Nothing to do");
 525         }
 526
 527         strbuf_release(&script_snippet);
 528
 529         return status ? -1 : 0;
 530 }
 531
 532 #define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
 533
 534 #define RESET_HEAD_DETACH (1<<0)
 535 #define RESET_HEAD_HARD (1<<1)
 536
 537 static int reset_head(struct object_id *oid, const char *action,
 538                       const char *switch_to_branch, unsigned flags,
 539                       const char *reflog_orig_head, const char *reflog_head)
 540 {
 541         unsigned detach_head = flags & RESET_HEAD_DETACH;
 542         unsigned reset_hard = flags & RESET_HEAD_HARD;
 543         struct object_id head_oid;
 544         struct tree_desc desc[2] = { { NULL }, { NULL } };
 545         struct lock_file lock = LOCK_INIT;
 546         struct unpack_trees_options unpack_tree_opts;
 547         struct tree *tree;
 548         const char *reflog_action;
 549         struct strbuf msg = STRBUF_INIT;
 550         size_t prefix_len;
 551         struct object_id *orig = NULL, oid_orig,
 552                 *old_orig = NULL, oid_old_orig;
 553         int ret = 0, nr = 0;
 554
 555         if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
 556                 BUG("Not a fully qualified branch: '%s'", switch_to_branch);
 557
 558         if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0) {
 559                 ret = -1;
 560                 goto leave_reset_head;
 561         }
 562
 563         if ((!oid || !reset_hard) && get_oid("HEAD", &head_oid)) {
 564                 ret = error(_("could not determine HEAD revision"));
 565                 goto leave_reset_head;
 566         }
 567
 568         if (!oid)
 569                 oid = &head_oid;
 570
 571         memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
 572         setup_unpack_trees_porcelain(&unpack_tree_opts, action);
 573         unpack_tree_opts.head_idx = 1;
 574         unpack_tree_opts.src_index = the_repository->index;
 575         unpack_tree_opts.dst_index = the_repository->index;
 576         unpack_tree_opts.fn = reset_hard ? oneway_merge : twoway_merge;
 577         unpack_tree_opts.update = 1;
 578         unpack_tree_opts.merge = 1;
 579         if (!detach_head)
 580                 unpack_tree_opts.reset = 1;
 581
 582         if (read_index_unmerged(the_repository->index) < 0) {
 583                 ret = error(_("could not read index"));
 584                 goto leave_reset_head;
 585         }
 586
 587         if (!reset_hard && !fill_tree_descriptor(&desc[nr++], &head_oid)) {
 588                 ret = error(_("failed to find tree of %s"),
 589                             oid_to_hex(&head_oid));
 590                 goto leave_reset_head;
 591         }
 592
 593         if (!fill_tree_descriptor(&desc[nr++], oid)) {
 594                 ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
 595                 goto leave_reset_head;
 596         }
 597
 598         if (unpack_trees(nr, desc, &unpack_tree_opts)) {
 599                 ret = -1;
 600                 goto leave_reset_head;
 601         }
 602
 603         tree = parse_tree_indirect(oid);
 604         prime_cache_tree(the_repository->index, tree);
 605
 606         if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0) {
 607                 ret = error(_("could not write index"));
 608                 goto leave_reset_head;
 609         }
 610
 611         reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
 612         strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
 613         prefix_len = msg.len;
 614
 615         if (!get_oid("ORIG_HEAD", &oid_old_orig))
 616                 old_orig = &oid_old_orig;
 617         if (!get_oid("HEAD", &oid_orig)) {
 618                 orig = &oid_orig;
 619                 if (!reflog_orig_head) {
 620                         strbuf_addstr(&msg, "updating ORIG_HEAD");
 621                         reflog_orig_head = msg.buf;
 622                 }
 623                 update_ref(reflog_orig_head, "ORIG_HEAD", orig, old_orig, 0,
 624                            UPDATE_REFS_MSG_ON_ERR);
 625         } else if (old_orig)
 626                 delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
 627         if (!reflog_head) {
 628                 strbuf_setlen(&msg, prefix_len);
 629                 strbuf_addstr(&msg, "updating HEAD");
 630                 reflog_head = msg.buf;
 631         }
 632         if (!switch_to_branch)
 633                 ret = update_ref(reflog_head, "HEAD", oid, orig,
 634                                  detach_head ? REF_NO_DEREF : 0,
 635                                  UPDATE_REFS_MSG_ON_ERR);
 636         else {
 637                 ret = create_symref("HEAD", switch_to_branch, msg.buf);
 638                 if (!ret)
 639                         ret = update_ref(reflog_head, "HEAD", oid, NULL, 0,
 640                                          UPDATE_REFS_MSG_ON_ERR);
 641         }
 642
 643 leave_reset_head:
 644         strbuf_release(&msg);
 645         rollback_lock_file(&lock);
 646         while (nr)
 647                 free((void *)desc[--nr].buffer);
 648         return ret;
 649 }
 650
 651 static int rebase_config(const char *var, const char *value, void *data)
 652 {
 653         struct rebase_options *opts = data;
 654
 655         if (!strcmp(var, "rebase.stat")) {
 656                 if (git_config_bool(var, value))
 657                         opts->flags |= REBASE_DIFFSTAT;
 658                 else
 659                         opts->flags &= !REBASE_DIFFSTAT;
 660                 return 0;
 661         }
 662
 663         if (!strcmp(var, "rebase.autosquash")) {
 664                 opts->autosquash = git_config_bool(var, value);
 665                 return 0;
 666         }
 667
 668         if (!strcmp(var, "commit.gpgsign")) {
 669                 free(opts->gpg_sign_opt);
 670                 opts->gpg_sign_opt = git_config_bool(var, value) ?
 671                         xstrdup("-S") : NULL;
 672                 return 0;
 673         }
 674
 675         if (!strcmp(var, "rebase.autostash")) {
 676                 opts->autostash = git_config_bool(var, value);
 677                 return 0;
 678         }
 679
 680         if (!strcmp(var, "rebase.reschedulefailedexec")) {
 681                 opts->reschedule_failed_exec = git_config_bool(var, value);
 682                 return 0;
 683         }
 684
 685         return git_default_config(var, value, data);
 686 }
 687
 688 /*
 689  * Determines whether the commits in from..to are linear, i.e. contain
 690  * no merge commits. This function *expects* `from` to be an ancestor of
 691  * `to`.
 692  */
 693 static int is_linear_history(struct commit *from, struct commit *to)
 694 {
 695         while (to && to != from) {
 696                 parse_commit(to);
 697                 if (!to->parents)
 698                         return 1;
 699                 if (to->parents->next)
 700                         return 0;
 701                 to = to->parents->item;
 702         }
 703         return 1;
 704 }
 705
 706 static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
 707                             struct object_id *merge_base)
 708 {
 709         struct commit *head = lookup_commit(the_repository, head_oid);
 710         struct commit_list *merge_bases;
 711         int res;
 712
 713         if (!head)
 714                 return 0;
 715
 716         merge_bases = get_merge_bases(onto, head);
 717         if (merge_bases && !merge_bases->next) {
 718                 oidcpy(merge_base, &merge_bases->item->object.oid);
 719                 res = oideq(merge_base, &onto->object.oid);
 720         } else {
 721                 oidcpy(merge_base, &null_oid);
 722                 res = 0;
 723         }
 724         free_commit_list(merge_bases);
 725         return res && is_linear_history(onto, head);
 726 }
 727
 728 /* -i followed by -m is still -i */
 729 static int parse_opt_merge(const struct option *opt, const char *arg, int unset)
 730 {
 731         struct rebase_options *opts = opt->value;
 732
 733         BUG_ON_OPT_NEG(unset);
 734         BUG_ON_OPT_ARG(arg);
 735
 736         if (!is_interactive(opts))
 737                 opts->type = REBASE_MERGE;
 738
 739         return 0;
 740 }
 741
 742 /* -i followed by -p is still explicitly interactive, but -p alone is not */
 743 static int parse_opt_interactive(const struct option *opt, const char *arg,
 744                                  int unset)
 745 {
 746         struct rebase_options *opts = opt->value;
 747
 748         BUG_ON_OPT_NEG(unset);
 749         BUG_ON_OPT_ARG(arg);
 750
 751         opts->type = REBASE_INTERACTIVE;
 752         opts->flags |= REBASE_INTERACTIVE_EXPLICIT;
 753
 754         return 0;
 755 }
 756
 757 static void NORETURN error_on_missing_default_upstream(void)
 758 {
 759         struct branch *current_branch = branch_get(NULL);
 760
 761         printf(_("%s\n"
 762                  "Please specify which branch you want to rebase against.\n"
 763                  "See git-rebase(1) for details.\n"
 764                  "\n"
 765                  "    git rebase '<branch>'\n"
 766                  "\n"),
 767                 current_branch ? _("There is no tracking information for "
 768                         "the current branch.") :
 769                         _("You are not currently on a branch."));
 770
 771         if (current_branch) {
 772                 const char *remote = current_branch->remote_name;
 773
 774                 if (!remote)
 775                         remote = _("<remote>");
 776
 777                 printf(_("If you wish to set tracking information for this "
 778                          "branch you can do so with:\n"
 779                          "\n"
 780                          "    git branch --set-upstream-to=%s/<branch> %s\n"
 781                          "\n"),
 782                        remote, current_branch->name);
 783         }
 784         exit(1);
 785 }
 786
 787 static void set_reflog_action(struct rebase_options *options)
 788 {
 789         const char *env;
 790         struct strbuf buf = STRBUF_INIT;
 791
 792         if (!is_interactive(options))
 793                 return;
 794
 795         env = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
 796         if (env && strcmp("rebase", env))
 797                 return; /* only override it if it is "rebase" */
 798
 799         strbuf_addf(&buf, "rebase -i (%s)", options->action);
 800         setenv(GIT_REFLOG_ACTION_ENVIRONMENT, buf.buf, 1);
 801         strbuf_release(&buf);
 802 }
 803
 804 int cmd_rebase(int argc, const char **argv, const char *prefix)
 805 {
 806         struct rebase_options options = {
 807                 .type = REBASE_UNSPECIFIED,
 808                 .flags = REBASE_NO_QUIET,
 809                 .git_am_opts = ARGV_ARRAY_INIT,
 810                 .allow_rerere_autoupdate  = -1,
 811                 .allow_empty_message = 1,
 812                 .git_format_patch_opt = STRBUF_INIT,
 813         };
 814         const char *branch_name;
 815         int ret, flags, total_argc, in_progress = 0;
 816         int ok_to_skip_pre_rebase = 0;
 817         struct strbuf msg = STRBUF_INIT;
 818         struct strbuf revisions = STRBUF_INIT;
 819         struct strbuf buf = STRBUF_INIT;
 820         struct object_id merge_base;
 821         enum {
 822                 NO_ACTION,
 823                 ACTION_CONTINUE,
 824                 ACTION_SKIP,
 825                 ACTION_ABORT,
 826                 ACTION_QUIT,
 827                 ACTION_EDIT_TODO,
 828                 ACTION_SHOW_CURRENT_PATCH,
 829         } action = NO_ACTION;
 830         const char *gpg_sign = NULL;
 831         struct string_list exec = STRING_LIST_INIT_NODUP;
 832         const char *rebase_merges = NULL;
 833         int fork_point = -1;
 834         struct string_list strategy_options = STRING_LIST_INIT_NODUP;
 835         struct object_id squash_onto;
 836         char *squash_onto_name = NULL;
 837         struct option builtin_rebase_options[] = {
 838                 OPT_STRING(0, "onto", &options.onto_name,
 839                            N_("revision"),
 840                            N_("rebase onto given branch instead of upstream")),
 841                 OPT_BOOL(0, "no-verify", &ok_to_skip_pre_rebase,
 842                          N_("allow pre-rebase hook to run")),
 843                 OPT_NEGBIT('q', "quiet", &options.flags,
 844                            N_("be quiet. implies --no-stat"),
 845                            REBASE_NO_QUIET| REBASE_VERBOSE | REBASE_DIFFSTAT),
 846                 OPT_BIT('v', "verbose", &options.flags,
 847                         N_("display a diffstat of what changed upstream"),
 848                         REBASE_NO_QUIET | REBASE_VERBOSE | REBASE_DIFFSTAT),
 849                 {OPTION_NEGBIT, 'n', "no-stat", &options.flags, NULL,
 850                         N_("do not show diffstat of what changed upstream"),
 851                         PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
 852                 OPT_BOOL(0, "signoff", &options.signoff,
 853                          N_("add a Signed-off-by: line to each commit")),
 854                 OPT_PASSTHRU_ARGV(0, "ignore-whitespace", &options.git_am_opts,
 855                                   NULL, N_("passed to 'git am'"),
 856                                   PARSE_OPT_NOARG),
 857                 OPT_PASSTHRU_ARGV(0, "committer-date-is-author-date",
 858                                   &options.git_am_opts, NULL,
 859                                   N_("passed to 'git am'"), PARSE_OPT_NOARG),
 860                 OPT_PASSTHRU_ARGV(0, "ignore-date", &options.git_am_opts, NULL,
 861                                   N_("passed to 'git am'"), PARSE_OPT_NOARG),
 862                 OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
 863                                   N_("passed to 'git apply'"), 0),
 864                 OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
 865                                   N_("action"), N_("passed to 'git apply'"), 0),
 866                 OPT_BIT('f', "force-rebase", &options.flags,
 867                         N_("cherry-pick all commits, even if unchanged"),
 868                         REBASE_FORCE),
 869                 OPT_BIT(0, "no-ff", &options.flags,
 870                         N_("cherry-pick all commits, even if unchanged"),
 871                         REBASE_FORCE),
 872                 OPT_CMDMODE(0, "continue", &action, N_("continue"),
 873                             ACTION_CONTINUE),
 874                 OPT_CMDMODE(0, "skip", &action,
 875                             N_("skip current patch and continue"), ACTION_SKIP),
 876                 OPT_CMDMODE(0, "abort", &action,
 877                             N_("abort and check out the original branch"),
 878                             ACTION_ABORT),
 879                 OPT_CMDMODE(0, "quit", &action,
 880                             N_("abort but keep HEAD where it is"), ACTION_QUIT),
 881                 OPT_CMDMODE(0, "edit-todo", &action, N_("edit the todo list "
 882                             "during an interactive rebase"), ACTION_EDIT_TODO),
 883                 OPT_CMDMODE(0, "show-current-patch", &action,
 884                             N_("show the patch file being applied or merged"),
 885                             ACTION_SHOW_CURRENT_PATCH),
 886                 { OPTION_CALLBACK, 'm', "merge", &options, NULL,
 887                         N_("use merging strategies to rebase"),
 888                         PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 889                         parse_opt_merge },
 890                 { OPTION_CALLBACK, 'i', "interactive", &options, NULL,
 891                         N_("let the user edit the list of commits to rebase"),
 892                         PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 893                         parse_opt_interactive },
 894                 OPT_SET_INT('p', "preserve-merges", &options.type,
 895                             N_("try to recreate merges instead of ignoring "
 896                                "them"), REBASE_PRESERVE_MERGES),
 897                 OPT_BOOL(0, "rerere-autoupdate",
 898                          &options.allow_rerere_autoupdate,
 899                          N_("allow rerere to update index with resolved "
 900                             "conflict")),
 901                 OPT_BOOL('k', "keep-empty", &options.keep_empty,
 902                          N_("preserve empty commits during rebase")),
 903                 OPT_BOOL(0, "autosquash", &options.autosquash,
 904                          N_("move commits that begin with "
 905                             "squash!/fixup! under -i")),
 906                 { OPTION_STRING, 'S', "gpg-sign", &gpg_sign, N_("key-id"),
 907                         N_("GPG-sign commits"),
 908                         PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 909                 OPT_BOOL(0, "autostash", &options.autostash,
 910                          N_("automatically stash/stash pop before and after")),
 911                 OPT_STRING_LIST('x', "exec", &exec, N_("exec"),
 912                                 N_("add exec lines after each commit of the "
 913                                    "editable list")),
 914                 OPT_BOOL(0, "allow-empty-message",
 915                          &options.allow_empty_message,
 916                          N_("allow rebasing commits with empty messages")),
 917                 {OPTION_STRING, 'r', "rebase-merges", &rebase_merges,
 918                         N_("mode"),
 919                         N_("try to rebase merges instead of skipping them"),
 920                         PARSE_OPT_OPTARG, NULL, (intptr_t)""},
 921                 OPT_BOOL(0, "fork-point", &fork_point,
 922                          N_("use 'merge-base --fork-point' to refine upstream")),
 923                 OPT_STRING('s', "strategy", &options.strategy,
 924                            N_("strategy"), N_("use the given merge strategy")),
 925                 OPT_STRING_LIST('X', "strategy-option", &strategy_options,
 926                                 N_("option"),
 927                                 N_("pass the argument through to the merge "
 928                                    "strategy")),
 929                 OPT_BOOL(0, "root", &options.root,
 930                          N_("rebase all reachable commits up to the root(s)")),
 931                 OPT_BOOL(0, "reschedule-failed-exec",
 932                          &options.reschedule_failed_exec,
 933                          N_("automatically re-schedule any `exec` that fails")),
 934                 OPT_END(),
 935         };
 936         int i;
 937
 938         /*
 939          * NEEDSWORK: Once the builtin rebase has been tested enough
 940          * and git-legacy-rebase.sh is retired to contrib/, this preamble
 941          * can be removed.
 942          */
 943
 944         if (!use_builtin_rebase()) {
 945                 const char *path = mkpath("%s/git-legacy-rebase",
 946                                           git_exec_path());
 947
 948                 if (sane_execvp(path, (char **)argv) < 0)
 949                         die_errno(_("could not exec %s"), path);
 950                 else
 951                         BUG("sane_execvp() returned???");
 952         }
 953
 954         if (argc == 2 && !strcmp(argv[1], "-h"))
 955                 usage_with_options(builtin_rebase_usage,
 956                                    builtin_rebase_options);
 957
 958         prefix = setup_git_directory();
 959         trace_repo_setup(prefix);
 960         setup_work_tree();
 961
 962         git_config(rebase_config, &options);
 963
 964         strbuf_reset(&buf);
 965         strbuf_addf(&buf, "%s/applying", apply_dir());
 966         if(file_exists(buf.buf))
 967                 die(_("It looks like 'git am' is in progress. Cannot rebase."));
 968
 969         if (is_directory(apply_dir())) {
 970                 options.type = REBASE_AM;
 971                 options.state_dir = apply_dir();
 972         } else if (is_directory(merge_dir())) {
 973                 strbuf_reset(&buf);
 974                 strbuf_addf(&buf, "%s/rewritten", merge_dir());
 975                 if (is_directory(buf.buf)) {
 976                         options.type = REBASE_PRESERVE_MERGES;
 977                         options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 978                 } else {
 979                         strbuf_reset(&buf);
 980                         strbuf_addf(&buf, "%s/interactive", merge_dir());
 981                         if(file_exists(buf.buf)) {
 982                                 options.type = REBASE_INTERACTIVE;
 983                                 options.flags |= REBASE_INTERACTIVE_EXPLICIT;
 984                         } else
 985                                 options.type = REBASE_MERGE;
 986                 }
 987                 options.state_dir = merge_dir();
 988         }
 989
 990         if (options.type != REBASE_UNSPECIFIED)
 991                 in_progress = 1;
 992
 993         total_argc = argc;
 994         argc = parse_options(argc, argv, prefix,
 995                              builtin_rebase_options,
 996                              builtin_rebase_usage, 0);
 997
 998         if (action != NO_ACTION && total_argc != 2) {
 999                 usage_with_options(builtin_rebase_usage,
1000                                    builtin_rebase_options);
1001         }
1002
1003         if (argc > 2)
1004                 usage_with_options(builtin_rebase_usage,
1005                                    builtin_rebase_options);
1006
1007         if (action != NO_ACTION && !in_progress)
1008                 die(_("No rebase in progress?"));
1009         setenv(GIT_REFLOG_ACTION_ENVIRONMENT, "rebase", 0);
1010
1011         if (action == ACTION_EDIT_TODO && !is_interactive(&options))
1012                 die(_("The --edit-todo action can only be used during "
1013                       "interactive rebase."));
1014
1015         switch (action) {
1016         case ACTION_CONTINUE: {
1017                 struct object_id head;
1018                 struct lock_file lock_file = LOCK_INIT;
1019                 int fd;
1020
1021                 options.action = "continue";
1022                 set_reflog_action(&options);
1023
1024                 /* Sanity check */
1025                 if (get_oid("HEAD", &head))
1026                         die(_("Cannot read HEAD"));
1027
1028                 fd = hold_locked_index(&lock_file, 0);
1029                 if (read_index(the_repository->index) < 0)
1030                         die(_("could not read index"));
1031                 refresh_index(the_repository->index, REFRESH_QUIET, NULL, NULL,
1032                               NULL);
1033                 if (0 <= fd)
1034                         update_index_if_able(the_repository->index,
1035                                              &lock_file);
1036                 rollback_lock_file(&lock_file);
1037
1038                 if (has_unstaged_changes(1)) {
1039                         puts(_("You must edit all merge conflicts and then\n"
1040                                "mark them as resolved using git add"));
1041                         exit(1);
1042                 }
1043                 if (read_basic_state(&options))
1044                         exit(1);
1045                 goto run_rebase;
1046         }
1047         case ACTION_SKIP: {
1048                 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1049
1050                 options.action = "skip";
1051                 set_reflog_action(&options);
1052
1053                 rerere_clear(&merge_rr);
1054                 string_list_clear(&merge_rr, 1);
1055
1056                 if (reset_head(NULL, "reset", NULL, RESET_HEAD_HARD,
1057                                NULL, NULL) < 0)
1058                         die(_("could not discard worktree changes"));
1059                 remove_branch_state();
1060                 if (read_basic_state(&options))
1061                         exit(1);
1062                 goto run_rebase;
1063         }
1064         case ACTION_ABORT: {
1065                 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1066                 options.action = "abort";
1067                 set_reflog_action(&options);
1068
1069                 rerere_clear(&merge_rr);
1070                 string_list_clear(&merge_rr, 1);
1071
1072                 if (read_basic_state(&options))
1073                         exit(1);
1074                 if (reset_head(&options.orig_head, "reset",
1075                                options.head_name, RESET_HEAD_HARD,
1076                                NULL, NULL) < 0)
1077                         die(_("could not move back to %s"),
1078                             oid_to_hex(&options.orig_head));
1079                 remove_branch_state();
1080                 ret = finish_rebase(&options);
1081                 goto cleanup;
1082         }
1083         case ACTION_QUIT: {
1084                 strbuf_reset(&buf);
1085                 strbuf_addstr(&buf, options.state_dir);
1086                 ret = !!remove_dir_recursively(&buf, 0);
1087                 if (ret)
1088                         die(_("could not remove '%s'"), options.state_dir);
1089                 goto cleanup;
1090         }
1091         case ACTION_EDIT_TODO:
1092                 options.action = "edit-todo";
1093                 options.dont_finish_rebase = 1;
1094                 goto run_rebase;
1095         case ACTION_SHOW_CURRENT_PATCH:
1096                 options.action = "show-current-patch";
1097                 options.dont_finish_rebase = 1;
1098                 goto run_rebase;
1099         case NO_ACTION:
1100                 break;
1101         default:
1102                 BUG("action: %d", action);
1103         }
1104
1105         /* Make sure no rebase is in progress */
1106         if (in_progress) {
1107                 const char *last_slash = strrchr(options.state_dir, '/');
1108                 const char *state_dir_base =
1109                         last_slash ? last_slash + 1 : options.state_dir;
1110                 const char *cmd_live_rebase =
1111                         "git rebase (--continue | --abort | --skip)";
1112                 strbuf_reset(&buf);
1113                 strbuf_addf(&buf, "rm -fr \"%s\"", options.state_dir);
1114                 die(_("It seems that there is already a %s directory, and\n"
1115                       "I wonder if you are in the middle of another rebase.  "
1116                       "If that is the\n"
1117                       "case, please try\n\t%s\n"
1118                       "If that is not the case, please\n\t%s\n"
1119                       "and run me again.  I am stopping in case you still "
1120                       "have something\n"
1121                       "valuable there.\n"),
1122                     state_dir_base, cmd_live_rebase, buf.buf);
1123         }
1124
1125         for (i = 0; i < options.git_am_opts.argc; i++) {
1126                 const char *option = options.git_am_opts.argv[i], *p;
1127                 if (!strcmp(option, "--committer-date-is-author-date") ||
1128                     !strcmp(option, "--ignore-date") ||
1129                     !strcmp(option, "--whitespace=fix") ||
1130                     !strcmp(option, "--whitespace=strip"))
1131                         options.flags |= REBASE_FORCE;
1132                 else if (skip_prefix(option, "-C", &p)) {
1133                         while (*p)
1134                                 if (!isdigit(*(p++)))
1135                                         die(_("switch `C' expects a "
1136                                               "numerical value"));
1137                 } else if (skip_prefix(option, "--whitespace=", &p)) {
1138                         if (*p && strcmp(p, "warn") && strcmp(p, "nowarn") &&
1139                             strcmp(p, "error") && strcmp(p, "error-all"))
1140                                 die("Invalid whitespace option: '%s'", p);
1141                 }
1142         }
1143
1144         if (!(options.flags & REBASE_NO_QUIET))
1145                 argv_array_push(&options.git_am_opts, "-q");
1146
1147         if (options.keep_empty)
1148                 imply_interactive(&options, "--keep-empty");
1149
1150         if (gpg_sign) {
1151                 free(options.gpg_sign_opt);
1152                 options.gpg_sign_opt = xstrfmt("-S%s", gpg_sign);
1153         }
1154
1155         if (exec.nr) {
1156                 int i;
1157
1158                 imply_interactive(&options, "--exec");
1159
1160                 strbuf_reset(&buf);
1161                 for (i = 0; i < exec.nr; i++)
1162                         strbuf_addf(&buf, "exec %s\n", exec.items[i].string);
1163                 options.cmd = xstrdup(buf.buf);
1164         }
1165
1166         if (rebase_merges) {
1167                 if (!*rebase_merges)
1168                         ; /* default mode; do nothing */
1169                 else if (!strcmp("rebase-cousins", rebase_merges))
1170                         options.rebase_cousins = 1;
1171                 else if (strcmp("no-rebase-cousins", rebase_merges))
1172                         die(_("Unknown mode: %s"), rebase_merges);
1173                 options.rebase_merges = 1;
1174                 imply_interactive(&options, "--rebase-merges");
1175         }
1176
1177         if (strategy_options.nr) {
1178                 int i;
1179
1180                 if (!options.strategy)
1181                         options.strategy = "recursive";
1182
1183                 strbuf_reset(&buf);
1184                 for (i = 0; i < strategy_options.nr; i++)
1185                         strbuf_addf(&buf, " --%s",
1186                                     strategy_options.items[i].string);
1187                 options.strategy_opts = xstrdup(buf.buf);
1188         }
1189
1190         if (options.strategy) {
1191                 options.strategy = xstrdup(options.strategy);
1192                 switch (options.type) {
1193                 case REBASE_AM:
1194                         die(_("--strategy requires --merge or --interactive"));
1195                 case REBASE_MERGE:
1196                 case REBASE_INTERACTIVE:
1197                 case REBASE_PRESERVE_MERGES:
1198                         /* compatible */
1199                         break;
1200                 case REBASE_UNSPECIFIED:
1201                         options.type = REBASE_MERGE;
1202                         break;
1203                 default:
1204                         BUG("unhandled rebase type (%d)", options.type);
1205                 }
1206         }
1207
1208         if (options.root && !options.onto_name)
1209                 imply_interactive(&options, "--root without --onto");
1210
1211         if (isatty(2) && options.flags & REBASE_NO_QUIET)
1212                 strbuf_addstr(&options.git_format_patch_opt, " --progress");
1213
1214         switch (options.type) {
1215         case REBASE_MERGE:
1216         case REBASE_INTERACTIVE:
1217         case REBASE_PRESERVE_MERGES:
1218                 options.state_dir = merge_dir();
1219                 break;
1220         case REBASE_AM:
1221                 options.state_dir = apply_dir();
1222                 break;
1223         default:
1224                 /* the default rebase backend is `--am` */
1225                 options.type = REBASE_AM;
1226                 options.state_dir = apply_dir();
1227                 break;
1228         }
1229
1230         if (options.reschedule_failed_exec && !is_interactive(&options))
1231                 die(_("--reschedule-failed-exec requires an interactive rebase"));
1232
1233         if (options.git_am_opts.argc) {
1234                 /* all am options except -q are compatible only with --am */
1235                 for (i = options.git_am_opts.argc - 1; i >= 0; i--)
1236                         if (strcmp(options.git_am_opts.argv[i], "-q"))
1237                                 break;
1238
1239                 if (is_interactive(&options) && i >= 0)
1240                         die(_("error: cannot combine interactive options "
1241                               "(--interactive, --exec, --rebase-merges, "
1242                               "--preserve-merges, --keep-empty, --root + "
1243                               "--onto) with am options (%s)"), buf.buf);
1244                 if (options.type == REBASE_MERGE && i >= 0)
1245                         die(_("error: cannot combine merge options (--merge, "
1246                               "--strategy, --strategy-option) with am options "
1247                               "(%s)"), buf.buf);
1248         }
1249
1250         if (options.signoff) {
1251                 if (options.type == REBASE_PRESERVE_MERGES)
1252                         die("cannot combine '--signoff' with "
1253                             "'--preserve-merges'");
1254                 argv_array_push(&options.git_am_opts, "--signoff");
1255                 options.flags |= REBASE_FORCE;
1256         }
1257
1258         if (options.type == REBASE_PRESERVE_MERGES) {
1259                 /*
1260                  * Note: incompatibility with --signoff handled in signoff block above
1261                  * Note: incompatibility with --interactive is just a strong warning;
1262                  *       git-rebase.txt caveats with "unless you know what you are doing"
1263                  */
1264                 if (options.rebase_merges)
1265                         die(_("error: cannot combine '--preserve-merges' with "
1266                               "'--rebase-merges'"));
1267
1268                 if (options.reschedule_failed_exec)
1269                         die(_("error: cannot combine '--preserve-merges' with "
1270                               "'--reschedule-failed-exec'"));
1271         }
1272
1273         if (options.rebase_merges) {
1274                 if (strategy_options.nr)
1275                         die(_("error: cannot combine '--rebase-merges' with "
1276                               "'--strategy-option'"));
1277                 if (options.strategy)
1278                         die(_("error: cannot combine '--rebase-merges' with "
1279                               "'--strategy'"));
1280         }
1281
1282         if (!options.root) {
1283                 if (argc < 1) {
1284                         struct branch *branch;
1285
1286                         branch = branch_get(NULL);
1287                         options.upstream_name = branch_get_upstream(branch,
1288                                                                     NULL);
1289                         if (!options.upstream_name)
1290                                 error_on_missing_default_upstream();
1291                         if (fork_point < 0)
1292                                 fork_point = 1;
1293                 } else {
1294                         options.upstream_name = argv[0];
1295                         argc--;
1296                         argv++;
1297                         if (!strcmp(options.upstream_name, "-"))
1298                                 options.upstream_name = "@{-1}";
1299                 }
1300                 options.upstream = peel_committish(options.upstream_name);
1301                 if (!options.upstream)
1302                         die(_("invalid upstream '%s'"), options.upstream_name);
1303                 options.upstream_arg = options.upstream_name;
1304         } else {
1305                 if (!options.onto_name) {
1306                         if (commit_tree("", 0, the_hash_algo->empty_tree, NULL,
1307                                         &squash_onto, NULL, NULL) < 0)
1308                                 die(_("Could not create new root commit"));
1309                         options.squash_onto = &squash_onto;
1310                         options.onto_name = squash_onto_name =
1311                                 xstrdup(oid_to_hex(&squash_onto));
1312                 }
1313                 options.upstream_name = NULL;
1314                 options.upstream = NULL;
1315                 if (argc > 1)
1316                         usage_with_options(builtin_rebase_usage,
1317                                            builtin_rebase_options);
1318                 options.upstream_arg = "--root";
1319         }
1320
1321         /* Make sure the branch to rebase onto is valid. */
1322         if (!options.onto_name)
1323                 options.onto_name = options.upstream_name;
1324         if (strstr(options.onto_name, "...")) {
1325                 if (get_oid_mb(options.onto_name, &merge_base) < 0)
1326                         die(_("'%s': need exactly one merge base"),
1327                             options.onto_name);
1328                 options.onto = lookup_commit_or_die(&merge_base,
1329                                                     options.onto_name);
1330         } else {
1331                 options.onto = peel_committish(options.onto_name);
1332                 if (!options.onto)
1333                         die(_("Does not point to a valid commit '%s'"),
1334                                 options.onto_name);
1335         }
1336
1337         /*
1338          * If the branch to rebase is given, that is the branch we will rebase
1339          * branch_name -- branch/commit being rebased, or
1340          *                HEAD (already detached)
1341          * orig_head -- commit object name of tip of the branch before rebasing
1342          * head_name -- refs/heads/<that-branch> or NULL (detached HEAD)
1343          */
1344         if (argc == 1) {
1345                 /* Is it "rebase other branchname" or "rebase other commit"? */
1346                 branch_name = argv[0];
1347                 options.switch_to = argv[0];
1348
1349                 /* Is it a local branch? */
1350                 strbuf_reset(&buf);
1351                 strbuf_addf(&buf, "refs/heads/%s", branch_name);
1352                 if (!read_ref(buf.buf, &options.orig_head))
1353                         options.head_name = xstrdup(buf.buf);
1354                 /* If not is it a valid ref (branch or commit)? */
1355                 else if (!get_oid(branch_name, &options.orig_head))
1356                         options.head_name = NULL;
1357                 else
1358                         die(_("fatal: no such branch/commit '%s'"),
1359                             branch_name);
1360         } else if (argc == 0) {
1361                 /* Do not need to switch branches, we are already on it. */
1362                 options.head_name =
1363                         xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
1364                                          &flags));
1365                 if (!options.head_name)
1366                         die(_("No such ref: %s"), "HEAD");
1367                 if (flags & REF_ISSYMREF) {
1368                         if (!skip_prefix(options.head_name,
1369                                          "refs/heads/", &branch_name))
1370                                 branch_name = options.head_name;
1371
1372                 } else {
1373                         free(options.head_name);
1374                         options.head_name = NULL;
1375                         branch_name = "HEAD";
1376                 }
1377                 if (get_oid("HEAD", &options.orig_head))
1378                         die(_("Could not resolve HEAD to a revision"));
1379         } else
1380                 BUG("unexpected number of arguments left to parse");
1381
1382         if (fork_point > 0) {
1383                 struct commit *head =
1384                         lookup_commit_reference(the_repository,
1385                                                 &options.orig_head);
1386                 options.restrict_revision =
1387                         get_fork_point(options.upstream_name, head);
1388         }
1389
1390         if (read_index(the_repository->index) < 0)
1391                 die(_("could not read index"));
1392
1393         if (options.autostash) {
1394                 struct lock_file lock_file = LOCK_INIT;
1395                 int fd;
1396
1397                 fd = hold_locked_index(&lock_file, 0);
1398                 refresh_cache(REFRESH_QUIET);
1399                 if (0 <= fd)
1400                         update_index_if_able(&the_index, &lock_file);
1401                 rollback_lock_file(&lock_file);
1402
1403                 if (has_unstaged_changes(1) || has_uncommitted_changes(1)) {
1404                         const char *autostash =
1405                                 state_dir_path("autostash", &options);
1406                         struct child_process stash = CHILD_PROCESS_INIT;
1407                         struct object_id oid;
1408                         struct commit *head =
1409                                 lookup_commit_reference(the_repository,
1410                                                         &options.orig_head);
1411
1412                         argv_array_pushl(&stash.args,
1413                                          "stash", "create", "autostash", NULL);
1414                         stash.git_cmd = 1;
1415                         stash.no_stdin = 1;
1416                         strbuf_reset(&buf);
1417                         if (capture_command(&stash, &buf, GIT_MAX_HEXSZ))
1418                                 die(_("Cannot autostash"));
1419                         strbuf_trim_trailing_newline(&buf);
1420                         if (get_oid(buf.buf, &oid))
1421                                 die(_("Unexpected stash response: '%s'"),
1422                                     buf.buf);
1423                         strbuf_reset(&buf);
1424                         strbuf_add_unique_abbrev(&buf, &oid, DEFAULT_ABBREV);
1425
1426                         if (safe_create_leading_directories_const(autostash))
1427                                 die(_("Could not create directory for '%s'"),
1428                                     options.state_dir);
1429                         write_file(autostash, "%s", oid_to_hex(&oid));
1430                         printf(_("Created autostash: %s\n"), buf.buf);
1431                         if (reset_head(&head->object.oid, "reset --hard",
1432                                        NULL, RESET_HEAD_HARD, NULL, NULL) < 0)
1433                                 die(_("could not reset --hard"));
1434                         printf(_("HEAD is now at %s"),
1435                                find_unique_abbrev(&head->object.oid,
1436                                                   DEFAULT_ABBREV));
1437                         strbuf_reset(&buf);
1438                         pp_commit_easy(CMIT_FMT_ONELINE, head, &buf);
1439                         if (buf.len > 0)
1440                                 printf(" %s", buf.buf);
1441                         putchar('\n');
1442
1443                         if (discard_index(the_repository->index) < 0 ||
1444                                 read_index(the_repository->index) < 0)
1445                                 die(_("could not read index"));
1446                 }
1447         }
1448
1449         if (require_clean_work_tree("rebase",
1450                                     _("Please commit or stash them."), 1, 1)) {
1451                 ret = 1;
1452                 goto cleanup;
1453         }
1454
1455         /*
1456          * Now we are rebasing commits upstream..orig_head (or with --root,
1457          * everything leading up to orig_head) on top of onto.
1458          */
1459
1460         /*
1461          * Check if we are already based on onto with linear history,
1462          * but this should be done only when upstream and onto are the same
1463          * and if this is not an interactive rebase.
1464          */
1465         if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
1466             !is_interactive(&options) && !options.restrict_revision &&
1467             options.upstream &&
1468             !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
1469                 int flag;
1470
1471                 if (!(options.flags & REBASE_FORCE)) {
1472                         /* Lazily switch to the target branch if needed... */
1473                         if (options.switch_to) {
1474                                 struct object_id oid;
1475
1476                                 if (get_oid(options.switch_to, &oid) < 0) {
1477                                         ret = !!error(_("could not parse '%s'"),
1478                                                       options.switch_to);
1479                                         goto cleanup;
1480                                 }
1481
1482                                 strbuf_reset(&buf);
1483                                 strbuf_addf(&buf, "%s: checkout %s",
1484                                             getenv(GIT_REFLOG_ACTION_ENVIRONMENT),
1485                                             options.switch_to);
1486                                 if (reset_head(&oid, "checkout",
1487                                                options.head_name, 0,
1488                                                NULL, buf.buf) < 0) {
1489                                         ret = !!error(_("could not switch to "
1490                                                         "%s"),
1491                                                       options.switch_to);
1492                                         goto cleanup;
1493                                 }
1494                         }
1495
1496                         if (!(options.flags & REBASE_NO_QUIET))
1497                                 ; /* be quiet */
1498                         else if (!strcmp(branch_name, "HEAD") &&
1499                                  resolve_ref_unsafe("HEAD", 0, NULL, &flag))
1500                                 puts(_("HEAD is up to date."));
1501                         else
1502                                 printf(_("Current branch %s is up to date.\n"),
1503                                        branch_name);
1504                         ret = !!finish_rebase(&options);
1505                         goto cleanup;
1506                 } else if (!(options.flags & REBASE_NO_QUIET))
1507                         ; /* be quiet */
1508                 else if (!strcmp(branch_name, "HEAD") &&
1509                          resolve_ref_unsafe("HEAD", 0, NULL, &flag))
1510                         puts(_("HEAD is up to date, rebase forced."));
1511                 else
1512                         printf(_("Current branch %s is up to date, rebase "
1513                                  "forced.\n"), branch_name);
1514         }
1515
1516         /* If a hook exists, give it a chance to interrupt*/
1517         if (!ok_to_skip_pre_rebase &&
1518             run_hook_le(NULL, "pre-rebase", options.upstream_arg,
1519                         argc ? argv[0] : NULL, NULL))
1520                 die(_("The pre-rebase hook refused to rebase."));
1521
1522         if (options.flags & REBASE_DIFFSTAT) {
1523                 struct diff_options opts;
1524
1525                 if (options.flags & REBASE_VERBOSE) {
1526                         if (is_null_oid(&merge_base))
1527                                 printf(_("Changes to %s:\n"),
1528                                        oid_to_hex(&options.onto->object.oid));
1529                         else
1530                                 printf(_("Changes from %s to %s:\n"),
1531                                        oid_to_hex(&merge_base),
1532                                        oid_to_hex(&options.onto->object.oid));
1533                 }
1534
1535                 /* We want color (if set), but no pager */
1536                 diff_setup(&opts);
1537                 opts.stat_width = -1; /* use full terminal width */
1538                 opts.stat_graph_width = -1; /* respect statGraphWidth config */
1539                 opts.output_format |=
1540                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
1541                 opts.detect_rename = DIFF_DETECT_RENAME;
1542                 diff_setup_done(&opts);
1543                 diff_tree_oid(is_null_oid(&merge_base) ?
1544                               the_hash_algo->empty_tree : &merge_base,
1545                               &options.onto->object.oid, "", &opts);
1546                 diffcore_std(&opts);
1547                 diff_flush(&opts);
1548         }
1549
1550         if (is_interactive(&options))
1551                 goto run_rebase;
1552
1553         /* Detach HEAD and reset the tree */
1554         if (options.flags & REBASE_NO_QUIET)
1555                 printf(_("First, rewinding head to replay your work on top of "
1556                          "it...\n"));
1557
1558         strbuf_addf(&msg, "%s: checkout %s",
1559                     getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
1560         if (reset_head(&options.onto->object.oid, "checkout", NULL,
1561                        RESET_HEAD_DETACH, NULL, msg.buf))
1562                 die(_("Could not detach HEAD"));
1563         strbuf_release(&msg);
1564
1565         /*
1566          * If the onto is a proper descendant of the tip of the branch, then
1567          * we just fast-forwarded.
1568          */
1569         strbuf_reset(&msg);
1570         if (!oidcmp(&merge_base, &options.orig_head)) {
1571                 printf(_("Fast-forwarded %s to %s.\n"),
1572                         branch_name, options.onto_name);
1573                 strbuf_addf(&msg, "rebase finished: %s onto %s",
1574                         options.head_name ? options.head_name : "detached HEAD",
1575                         oid_to_hex(&options.onto->object.oid));
1576                 reset_head(NULL, "Fast-forwarded", options.head_name, 0,
1577                            "HEAD", msg.buf);
1578                 strbuf_release(&msg);
1579                 ret = !!finish_rebase(&options);
1580                 goto cleanup;
1581         }
1582
1583         strbuf_addf(&revisions, "%s..%s",
1584                     options.root ? oid_to_hex(&options.onto->object.oid) :
1585                     (options.restrict_revision ?
1586                      oid_to_hex(&options.restrict_revision->object.oid) :
1587                      oid_to_hex(&options.upstream->object.oid)),
1588                     oid_to_hex(&options.orig_head));
1589
1590         options.revisions = revisions.buf;
1591
1592 run_rebase:
1593         ret = !!run_specific_rebase(&options);
1594
1595 cleanup:
1596         strbuf_release(&revisions);
1597         free(options.head_name);
1598         free(options.gpg_sign_opt);
1599         free(options.cmd);
1600         free(squash_onto_name);
1601         return ret;
1602 }