builtin/revert.c

   1 #include "cache.h"
   2 #include "builtin.h"
   3 #include "object.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "run-command.h"
   7 #include "exec_cmd.h"
   8 #include "utf8.h"
   9 #include "parse-options.h"
  10 #include "cache-tree.h"
  11 #include "diff.h"
  12 #include "revision.h"
  13 #include "rerere.h"
  14 #include "merge-recursive.h"
  15 #include "refs.h"
  16 #include "dir.h"
  17 #include "sequencer.h"
  18
  19 /*
  20  * This implements the builtins revert and cherry-pick.
  21  *
  22  * Copyright (c) 2007 Johannes E. Schindelin
  23  *
  24  * Based on git-revert.sh, which is
  25  *
  26  * Copyright (c) 2005 Linus Torvalds
  27  * Copyright (c) 2005 Junio C Hamano
  28  */
  29
  30 static const char * const revert_usage[] = {
  31         "git revert [options] <commit-ish>",
  32         "git revert <subcommand>",
  33         NULL
  34 };
  35
  36 static const char * const cherry_pick_usage[] = {
  37         "git cherry-pick [options] <commit-ish>",
  38         "git cherry-pick <subcommand>",
  39         NULL
  40 };
  41
  42 enum replay_action { REVERT, CHERRY_PICK };
  43 enum replay_subcommand {
  44         REPLAY_NONE,
  45         REPLAY_REMOVE_STATE,
  46         REPLAY_CONTINUE,
  47         REPLAY_ROLLBACK
  48 };
  49
  50 struct replay_opts {
  51         enum replay_action action;
  52         enum replay_subcommand subcommand;
  53
  54         /* Boolean options */
  55         int edit;
  56         int record_origin;
  57         int no_commit;
  58         int signoff;
  59         int allow_ff;
  60         int allow_rerere_auto;
  61
  62         int mainline;
  63
  64         /* Merge strategy */
  65         const char *strategy;
  66         const char **xopts;
  67         size_t xopts_nr, xopts_alloc;
  68
  69         /* Only used by REPLAY_NONE */
  70         struct rev_info *revs;
  71 };
  72
  73 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  74
  75 static const char *action_name(const struct replay_opts *opts)
  76 {
  77         return opts->action == REVERT ? "revert" : "cherry-pick";
  78 }
  79
  80 static char *get_encoding(const char *message);
  81
  82 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
  83 {
  84         return opts->action == REVERT ? revert_usage : cherry_pick_usage;
  85 }
  86
  87 static int option_parse_x(const struct option *opt,
  88                           const char *arg, int unset)
  89 {
  90         struct replay_opts **opts_ptr = opt->value;
  91         struct replay_opts *opts = *opts_ptr;
  92
  93         if (unset)
  94                 return 0;
  95
  96         ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
  97         opts->xopts[opts->xopts_nr++] = xstrdup(arg);
  98         return 0;
  99 }
 100
 101 static void verify_opt_compatible(const char *me, const char *base_opt, ...)
 102 {
 103         const char *this_opt;
 104         va_list ap;
 105
 106         va_start(ap, base_opt);
 107         while ((this_opt = va_arg(ap, const char *))) {
 108                 if (va_arg(ap, int))
 109                         break;
 110         }
 111         va_end(ap);
 112
 113         if (this_opt)
 114                 die(_("%s: %s cannot be used with %s"), me, this_opt, base_opt);
 115 }
 116
 117 static void verify_opt_mutually_compatible(const char *me, ...)
 118 {
 119         const char *opt1, *opt2 = NULL;
 120         va_list ap;
 121
 122         va_start(ap, me);
 123         while ((opt1 = va_arg(ap, const char *))) {
 124                 if (va_arg(ap, int))
 125                         break;
 126         }
 127         if (opt1) {
 128                 while ((opt2 = va_arg(ap, const char *))) {
 129                         if (va_arg(ap, int))
 130                                 break;
 131                 }
 132         }
 133
 134         if (opt1 && opt2)
 135                 die(_("%s: %s cannot be used with %s"), me, opt1, opt2);
 136 }
 137
 138 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 139 {
 140         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
 141         const char *me = action_name(opts);
 142         int remove_state = 0;
 143         int contin = 0;
 144         int rollback = 0;
 145         struct option options[] = {
 146                 OPT_BOOLEAN(0, "quit", &remove_state, "end revert or cherry-pick sequence"),
 147                 OPT_BOOLEAN(0, "continue", &contin, "resume revert or cherry-pick sequence"),
 148                 OPT_BOOLEAN(0, "abort", &rollback, "cancel revert or cherry-pick sequence"),
 149                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
 150                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
 151                 OPT_NOOP_NOARG('r', NULL),
 152                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
 153                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
 154                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
 155                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
 156                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
 157                         "option for merge strategy", option_parse_x),
 158                 OPT_END(),
 159                 OPT_END(),
 160                 OPT_END(),
 161         };
 162
 163         if (opts->action == CHERRY_PICK) {
 164                 struct option cp_extra[] = {
 165                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 166                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
 167                         OPT_END(),
 168                 };
 169                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
 170                         die(_("program error"));
 171         }
 172
 173         argc = parse_options(argc, argv, NULL, options, usage_str,
 174                         PARSE_OPT_KEEP_ARGV0 |
 175                         PARSE_OPT_KEEP_UNKNOWN);
 176
 177         /* Check for incompatible subcommands */
 178         verify_opt_mutually_compatible(me,
 179                                 "--quit", remove_state,
 180                                 "--continue", contin,
 181                                 "--abort", rollback,
 182                                 NULL);
 183
 184         /* Set the subcommand */
 185         if (remove_state)
 186                 opts->subcommand = REPLAY_REMOVE_STATE;
 187         else if (contin)
 188                 opts->subcommand = REPLAY_CONTINUE;
 189         else if (rollback)
 190                 opts->subcommand = REPLAY_ROLLBACK;
 191         else
 192                 opts->subcommand = REPLAY_NONE;
 193
 194         /* Check for incompatible command line arguments */
 195         if (opts->subcommand != REPLAY_NONE) {
 196                 char *this_operation;
 197                 if (opts->subcommand == REPLAY_REMOVE_STATE)
 198                         this_operation = "--quit";
 199                 else if (opts->subcommand == REPLAY_CONTINUE)
 200                         this_operation = "--continue";
 201                 else {
 202                         assert(opts->subcommand == REPLAY_ROLLBACK);
 203                         this_operation = "--abort";
 204                 }
 205
 206                 verify_opt_compatible(me, this_operation,
 207                                 "--no-commit", opts->no_commit,
 208                                 "--signoff", opts->signoff,
 209                                 "--mainline", opts->mainline,
 210                                 "--strategy", opts->strategy ? 1 : 0,
 211                                 "--strategy-option", opts->xopts ? 1 : 0,
 212                                 "-x", opts->record_origin,
 213                                 "--ff", opts->allow_ff,
 214                                 NULL);
 215         }
 216
 217         if (opts->allow_ff)
 218                 verify_opt_compatible(me, "--ff",
 219                                 "--signoff", opts->signoff,
 220                                 "--no-commit", opts->no_commit,
 221                                 "-x", opts->record_origin,
 222                                 "--edit", opts->edit,
 223                                 NULL);
 224
 225         if (opts->subcommand != REPLAY_NONE) {
 226                 opts->revs = NULL;
 227         } else {
 228                 opts->revs = xmalloc(sizeof(*opts->revs));
 229                 init_revisions(opts->revs, NULL);
 230                 opts->revs->no_walk = 1;
 231                 if (argc < 2)
 232                         usage_with_options(usage_str, options);
 233                 argc = setup_revisions(argc, argv, opts->revs, NULL);
 234         }
 235
 236         if (argc > 1)
 237                 usage_with_options(usage_str, options);
 238 }
 239
 240 struct commit_message {
 241         char *parent_label;
 242         const char *label;
 243         const char *subject;
 244         char *reencoded_message;
 245         const char *message;
 246 };
 247
 248 static int get_message(struct commit *commit, struct commit_message *out)
 249 {
 250         const char *encoding;
 251         const char *abbrev, *subject;
 252         int abbrev_len, subject_len;
 253         char *q;
 254
 255         if (!commit->buffer)
 256                 return -1;
 257         encoding = get_encoding(commit->buffer);
 258         if (!encoding)
 259                 encoding = "UTF-8";
 260         if (!git_commit_encoding)
 261                 git_commit_encoding = "UTF-8";
 262
 263         out->reencoded_message = NULL;
 264         out->message = commit->buffer;
 265         if (strcmp(encoding, git_commit_encoding))
 266                 out->reencoded_message = reencode_string(commit->buffer,
 267                                         git_commit_encoding, encoding);
 268         if (out->reencoded_message)
 269                 out->message = out->reencoded_message;
 270
 271         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 272         abbrev_len = strlen(abbrev);
 273
 274         subject_len = find_commit_subject(out->message, &subject);
 275
 276         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 277                               strlen("... ") + subject_len + 1);
 278         q = out->parent_label;
 279         q = mempcpy(q, "parent of ", strlen("parent of "));
 280         out->label = q;
 281         q = mempcpy(q, abbrev, abbrev_len);
 282         q = mempcpy(q, "... ", strlen("... "));
 283         out->subject = q;
 284         q = mempcpy(q, subject, subject_len);
 285         *q = '\0';
 286         return 0;
 287 }
 288
 289 static void free_message(struct commit_message *msg)
 290 {
 291         free(msg->parent_label);
 292         free(msg->reencoded_message);
 293 }
 294
 295 static char *get_encoding(const char *message)
 296 {
 297         const char *p = message, *eol;
 298
 299         while (*p && *p != '\n') {
 300                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 301                         ; /* do nothing */
 302                 if (!prefixcmp(p, "encoding ")) {
 303                         char *result = xmalloc(eol - 8 - p);
 304                         strlcpy(result, p + 9, eol - 8 - p);
 305                         return result;
 306                 }
 307                 p = eol;
 308                 if (*p == '\n')
 309                         p++;
 310         }
 311         return NULL;
 312 }
 313
 314 static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
 315 {
 316         const char *filename;
 317         int fd;
 318         struct strbuf buf = STRBUF_INIT;
 319
 320         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 321
 322         filename = git_path("%s", pseudoref);
 323         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 324         if (fd < 0)
 325                 die_errno(_("Could not open '%s' for writing"), filename);
 326         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 327                 die_errno(_("Could not write to '%s'"), filename);
 328         strbuf_release(&buf);
 329 }
 330
 331 static void print_advice(int show_hint)
 332 {
 333         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 334
 335         if (msg) {
 336                 fprintf(stderr, "%s\n", msg);
 337                 /*
 338                  * A conflict has occured but the porcelain
 339                  * (typically rebase --interactive) wants to take care
 340                  * of the commit itself so remove CHERRY_PICK_HEAD
 341                  */
 342                 unlink(git_path("CHERRY_PICK_HEAD"));
 343                 return;
 344         }
 345
 346         if (show_hint) {
 347                 advise("after resolving the conflicts, mark the corrected paths");
 348                 advise("with 'git add <paths>' or 'git rm <paths>'");
 349                 advise("and commit the result with 'git commit'");
 350         }
 351 }
 352
 353 static void write_message(struct strbuf *msgbuf, const char *filename)
 354 {
 355         static struct lock_file msg_file;
 356
 357         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 358                                                LOCK_DIE_ON_ERROR);
 359         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 360                 die_errno(_("Could not write to %s"), filename);
 361         strbuf_release(msgbuf);
 362         if (commit_lock_file(&msg_file) < 0)
 363                 die(_("Error wrapping up %s"), filename);
 364 }
 365
 366 static struct tree *empty_tree(void)
 367 {
 368         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 369 }
 370
 371 static int error_dirty_index(struct replay_opts *opts)
 372 {
 373         if (read_cache_unmerged())
 374                 return error_resolve_conflict(action_name(opts));
 375
 376         /* Different translation strings for cherry-pick and revert */
 377         if (opts->action == CHERRY_PICK)
 378                 error(_("Your local changes would be overwritten by cherry-pick."));
 379         else
 380                 error(_("Your local changes would be overwritten by revert."));
 381
 382         if (advice_commit_before_merge)
 383                 advise(_("Commit your changes or stash them to proceed."));
 384         return -1;
 385 }
 386
 387 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 388 {
 389         struct ref_lock *ref_lock;
 390
 391         read_cache();
 392         if (checkout_fast_forward(from, to))
 393                 exit(1); /* the callee should have complained already */
 394         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 395         return write_ref_sha1(ref_lock, to, "cherry-pick");
 396 }
 397
 398 static int do_recursive_merge(struct commit *base, struct commit *next,
 399                               const char *base_label, const char *next_label,
 400                               unsigned char *head, struct strbuf *msgbuf,
 401                               struct replay_opts *opts)
 402 {
 403         struct merge_options o;
 404         struct tree *result, *next_tree, *base_tree, *head_tree;
 405         int clean, index_fd;
 406         const char **xopt;
 407         static struct lock_file index_lock;
 408
 409         index_fd = hold_locked_index(&index_lock, 1);
 410
 411         read_cache();
 412
 413         init_merge_options(&o);
 414         o.ancestor = base ? base_label : "(empty tree)";
 415         o.branch1 = "HEAD";
 416         o.branch2 = next ? next_label : "(empty tree)";
 417
 418         head_tree = parse_tree_indirect(head);
 419         next_tree = next ? next->tree : empty_tree();
 420         base_tree = base ? base->tree : empty_tree();
 421
 422         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 423                 parse_merge_opt(&o, *xopt);
 424
 425         clean = merge_trees(&o,
 426                             head_tree,
 427                             next_tree, base_tree, &result);
 428
 429         if (active_cache_changed &&
 430             (write_cache(index_fd, active_cache, active_nr) ||
 431              commit_locked_index(&index_lock)))
 432                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 433                 die(_("%s: Unable to write new index file"), action_name(opts));
 434         rollback_lock_file(&index_lock);
 435
 436         if (!clean) {
 437                 int i;
 438                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 439                 for (i = 0; i < active_nr;) {
 440                         struct cache_entry *ce = active_cache[i++];
 441                         if (ce_stage(ce)) {
 442                                 strbuf_addch(msgbuf, '\t');
 443                                 strbuf_addstr(msgbuf, ce->name);
 444                                 strbuf_addch(msgbuf, '\n');
 445                                 while (i < active_nr && !strcmp(ce->name,
 446                                                 active_cache[i]->name))
 447                                         i++;
 448                         }
 449                 }
 450         }
 451
 452         return !clean;
 453 }
 454
 455 /*
 456  * If we are cherry-pick, and if the merge did not result in
 457  * hand-editing, we will hit this commit and inherit the original
 458  * author date and name.
 459  * If we are revert, or if our cherry-pick results in a hand merge,
 460  * we had better say that the current user is responsible for that.
 461  */
 462 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 463 {
 464         /* 6 is max possible length of our args array including NULL */
 465         const char *args[6];
 466         int i = 0;
 467
 468         args[i++] = "commit";
 469         args[i++] = "-n";
 470         if (opts->signoff)
 471                 args[i++] = "-s";
 472         if (!opts->edit) {
 473                 args[i++] = "-F";
 474                 args[i++] = defmsg;
 475         }
 476         args[i] = NULL;
 477
 478         return run_command_v_opt(args, RUN_GIT_CMD);
 479 }
 480
 481 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 482 {
 483         unsigned char head[20];
 484         struct commit *base, *next, *parent;
 485         const char *base_label, *next_label;
 486         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 487         char *defmsg = NULL;
 488         struct strbuf msgbuf = STRBUF_INIT;
 489         int res;
 490
 491         if (opts->no_commit) {
 492                 /*
 493                  * We do not intend to commit immediately.  We just want to
 494                  * merge the differences in, so let's compute the tree
 495                  * that represents the "current" state for merge-recursive
 496                  * to work on.
 497                  */
 498                 if (write_cache_as_tree(head, 0, NULL))
 499                         die (_("Your index file is unmerged."));
 500         } else {
 501                 if (get_sha1("HEAD", head))
 502                         return error(_("You do not have a valid HEAD"));
 503                 if (index_differs_from("HEAD", 0))
 504                         return error_dirty_index(opts);
 505         }
 506         discard_cache();
 507
 508         if (!commit->parents) {
 509                 parent = NULL;
 510         }
 511         else if (commit->parents->next) {
 512                 /* Reverting or cherry-picking a merge commit */
 513                 int cnt;
 514                 struct commit_list *p;
 515
 516                 if (!opts->mainline)
 517                         return error(_("Commit %s is a merge but no -m option was given."),
 518                                 sha1_to_hex(commit->object.sha1));
 519
 520                 for (cnt = 1, p = commit->parents;
 521                      cnt != opts->mainline && p;
 522                      cnt++)
 523                         p = p->next;
 524                 if (cnt != opts->mainline || !p)
 525                         return error(_("Commit %s does not have parent %d"),
 526                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 527                 parent = p->item;
 528         } else if (0 < opts->mainline)
 529                 return error(_("Mainline was specified but commit %s is not a merge."),
 530                         sha1_to_hex(commit->object.sha1));
 531         else
 532                 parent = commit->parents->item;
 533
 534         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 535                 return fast_forward_to(commit->object.sha1, head);
 536
 537         if (parent && parse_commit(parent) < 0)
 538                 /* TRANSLATORS: The first %s will be "revert" or
 539                    "cherry-pick", the second %s a SHA1 */
 540                 return error(_("%s: cannot parse parent commit %s"),
 541                         action_name(opts), sha1_to_hex(parent->object.sha1));
 542
 543         if (get_message(commit, &msg) != 0)
 544                 return error(_("Cannot get commit message for %s"),
 545                         sha1_to_hex(commit->object.sha1));
 546
 547         /*
 548          * "commit" is an existing commit.  We would want to apply
 549          * the difference it introduces since its first parent "prev"
 550          * on top of the current HEAD if we are cherry-pick.  Or the
 551          * reverse of it if we are revert.
 552          */
 553
 554         defmsg = git_pathdup("MERGE_MSG");
 555
 556         if (opts->action == REVERT) {
 557                 base = commit;
 558                 base_label = msg.label;
 559                 next = parent;
 560                 next_label = msg.parent_label;
 561                 strbuf_addstr(&msgbuf, "Revert \"");
 562                 strbuf_addstr(&msgbuf, msg.subject);
 563                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 564                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 565
 566                 if (commit->parents && commit->parents->next) {
 567                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 568                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 569                 }
 570                 strbuf_addstr(&msgbuf, ".\n");
 571         } else {
 572                 const char *p;
 573
 574                 base = parent;
 575                 base_label = msg.parent_label;
 576                 next = commit;
 577                 next_label = msg.label;
 578
 579                 /*
 580                  * Append the commit log message to msgbuf; it starts
 581                  * after the tree, parent, author, committer
 582                  * information followed by "\n\n".
 583                  */
 584                 p = strstr(msg.message, "\n\n");
 585                 if (p) {
 586                         p += 2;
 587                         strbuf_addstr(&msgbuf, p);
 588                 }
 589
 590                 if (opts->record_origin) {
 591                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 592                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 593                         strbuf_addstr(&msgbuf, ")\n");
 594                 }
 595         }
 596
 597         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
 598                 res = do_recursive_merge(base, next, base_label, next_label,
 599                                          head, &msgbuf, opts);
 600                 write_message(&msgbuf, defmsg);
 601         } else {
 602                 struct commit_list *common = NULL;
 603                 struct commit_list *remotes = NULL;
 604
 605                 write_message(&msgbuf, defmsg);
 606
 607                 commit_list_insert(base, &common);
 608                 commit_list_insert(next, &remotes);
 609                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 610                                         common, sha1_to_hex(head), remotes);
 611                 free_commit_list(common);
 612                 free_commit_list(remotes);
 613         }
 614
 615         /*
 616          * If the merge was clean or if it failed due to conflict, we write
 617          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 618          * However, if the merge did not even start, then we don't want to
 619          * write it at all.
 620          */
 621         if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
 622                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 623         if (opts->action == REVERT && ((opts->no_commit && res == 0) || res == 1))
 624                 write_cherry_pick_head(commit, "REVERT_HEAD");
 625
 626         if (res) {
 627                 error(opts->action == REVERT
 628                       ? _("could not revert %s... %s")
 629                       : _("could not apply %s... %s"),
 630                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 631                       msg.subject);
 632                 print_advice(res == 1);
 633                 rerere(opts->allow_rerere_auto);
 634         } else {
 635                 if (!opts->no_commit)
 636                         res = run_git_commit(defmsg, opts);
 637         }
 638
 639         free_message(&msg);
 640         free(defmsg);
 641
 642         return res;
 643 }
 644
 645 static void prepare_revs(struct replay_opts *opts)
 646 {
 647         if (opts->action != REVERT)
 648                 opts->revs->reverse ^= 1;
 649
 650         if (prepare_revision_walk(opts->revs))
 651                 die(_("revision walk setup failed"));
 652
 653         if (!opts->revs->commits)
 654                 die(_("empty commit set passed"));
 655 }
 656
 657 static void read_and_refresh_cache(struct replay_opts *opts)
 658 {
 659         static struct lock_file index_lock;
 660         int index_fd = hold_locked_index(&index_lock, 0);
 661         if (read_index_preload(&the_index, NULL) < 0)
 662                 die(_("git %s: failed to read the index"), action_name(opts));
 663         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 664         if (the_index.cache_changed) {
 665                 if (write_index(&the_index, index_fd) ||
 666                     commit_locked_index(&index_lock))
 667                         die(_("git %s: failed to refresh the index"), action_name(opts));
 668         }
 669         rollback_lock_file(&index_lock);
 670 }
 671
 672 /*
 673  * Append a commit to the end of the commit_list.
 674  *
 675  * next starts by pointing to the variable that holds the head of an
 676  * empty commit_list, and is updated to point to the "next" field of
 677  * the last item on the list as new commits are appended.
 678  *
 679  * Usage example:
 680  *
 681  *     struct commit_list *list;
 682  *     struct commit_list **next = &list;
 683  *
 684  *     next = commit_list_append(c1, next);
 685  *     next = commit_list_append(c2, next);
 686  *     assert(commit_list_count(list) == 2);
 687  *     return list;
 688  */
 689 static struct commit_list **commit_list_append(struct commit *commit,
 690                                                struct commit_list **next)
 691 {
 692         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 693         new->item = commit;
 694         *next = new;
 695         new->next = NULL;
 696         return &new->next;
 697 }
 698
 699 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 700                 struct replay_opts *opts)
 701 {
 702         struct commit_list *cur = NULL;
 703         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 704         const char *sha1_abbrev = NULL;
 705         const char *action_str = opts->action == REVERT ? "revert" : "pick";
 706
 707         for (cur = todo_list; cur; cur = cur->next) {
 708                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 709                 if (get_message(cur->item, &msg))
 710                         return error(_("Cannot get commit message for %s"), sha1_abbrev);
 711                 strbuf_addf(buf, "%s %s %s\n", action_str, sha1_abbrev, msg.subject);
 712         }
 713         return 0;
 714 }
 715
 716 static struct commit *parse_insn_line(char *start, struct replay_opts *opts)
 717 {
 718         unsigned char commit_sha1[20];
 719         char sha1_abbrev[40];
 720         enum replay_action action;
 721         int insn_len = 0;
 722         char *p, *q;
 723
 724         if (!prefixcmp(start, "pick ")) {
 725                 action = CHERRY_PICK;
 726                 insn_len = strlen("pick");
 727                 p = start + insn_len + 1;
 728         } else if (!prefixcmp(start, "revert ")) {
 729                 action = REVERT;
 730                 insn_len = strlen("revert");
 731                 p = start + insn_len + 1;
 732         } else
 733                 return NULL;
 734
 735         q = strchr(p, ' ');
 736         if (!q)
 737                 return NULL;
 738         q++;
 739
 740         strlcpy(sha1_abbrev, p, q - p);
 741
 742         /*
 743          * Verify that the action matches up with the one in
 744          * opts; we don't support arbitrary instructions
 745          */
 746         if (action != opts->action) {
 747                 const char *action_str;
 748                 action_str = action == REVERT ? "revert" : "cherry-pick";
 749                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 750                 return NULL;
 751         }
 752
 753         if (get_sha1(sha1_abbrev, commit_sha1) < 0)
 754                 return NULL;
 755
 756         return lookup_commit_reference(commit_sha1);
 757 }
 758
 759 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 760                         struct replay_opts *opts)
 761 {
 762         struct commit_list **next = todo_list;
 763         struct commit *commit;
 764         char *p = buf;
 765         int i;
 766
 767         for (i = 1; *p; i++) {
 768                 commit = parse_insn_line(p, opts);
 769                 if (!commit)
 770                         return error(_("Could not parse line %d."), i);
 771                 next = commit_list_append(commit, next);
 772                 p = strchrnul(p, '\n');
 773                 if (*p)
 774                         p++;
 775         }
 776         if (!*todo_list)
 777                 return error(_("No commits parsed."));
 778         return 0;
 779 }
 780
 781 static void read_populate_todo(struct commit_list **todo_list,
 782                         struct replay_opts *opts)
 783 {
 784         const char *todo_file = git_path(SEQ_TODO_FILE);
 785         struct strbuf buf = STRBUF_INIT;
 786         int fd, res;
 787
 788         fd = open(todo_file, O_RDONLY);
 789         if (fd < 0)
 790                 die_errno(_("Could not open %s"), todo_file);
 791         if (strbuf_read(&buf, fd, 0) < 0) {
 792                 close(fd);
 793                 strbuf_release(&buf);
 794                 die(_("Could not read %s."), todo_file);
 795         }
 796         close(fd);
 797
 798         res = parse_insn_buffer(buf.buf, todo_list, opts);
 799         strbuf_release(&buf);
 800         if (res)
 801                 die(_("Unusable instruction sheet: %s"), todo_file);
 802 }
 803
 804 static int populate_opts_cb(const char *key, const char *value, void *data)
 805 {
 806         struct replay_opts *opts = data;
 807         int error_flag = 1;
 808
 809         if (!value)
 810                 error_flag = 0;
 811         else if (!strcmp(key, "options.no-commit"))
 812                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 813         else if (!strcmp(key, "options.edit"))
 814                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 815         else if (!strcmp(key, "options.signoff"))
 816                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 817         else if (!strcmp(key, "options.record-origin"))
 818                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 819         else if (!strcmp(key, "options.allow-ff"))
 820                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 821         else if (!strcmp(key, "options.mainline"))
 822                 opts->mainline = git_config_int(key, value);
 823         else if (!strcmp(key, "options.strategy"))
 824                 git_config_string(&opts->strategy, key, value);
 825         else if (!strcmp(key, "options.strategy-option")) {
 826                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 827                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 828         } else
 829                 return error(_("Invalid key: %s"), key);
 830
 831         if (!error_flag)
 832                 return error(_("Invalid value for %s: %s"), key, value);
 833
 834         return 0;
 835 }
 836
 837 static void read_populate_opts(struct replay_opts **opts_ptr)
 838 {
 839         const char *opts_file = git_path(SEQ_OPTS_FILE);
 840
 841         if (!file_exists(opts_file))
 842                 return;
 843         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 844                 die(_("Malformed options sheet: %s"), opts_file);
 845 }
 846
 847 static void walk_revs_populate_todo(struct commit_list **todo_list,
 848                                 struct replay_opts *opts)
 849 {
 850         struct commit *commit;
 851         struct commit_list **next;
 852
 853         prepare_revs(opts);
 854
 855         next = todo_list;
 856         while ((commit = get_revision(opts->revs)))
 857                 next = commit_list_append(commit, next);
 858 }
 859
 860 static int create_seq_dir(void)
 861 {
 862         const char *seq_dir = git_path(SEQ_DIR);
 863
 864         if (file_exists(seq_dir)) {
 865                 error(_("a cherry-pick or revert is already in progress"));
 866                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 867                 return -1;
 868         }
 869         else if (mkdir(seq_dir, 0777) < 0)
 870                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 871         return 0;
 872 }
 873
 874 static void save_head(const char *head)
 875 {
 876         const char *head_file = git_path(SEQ_HEAD_FILE);
 877         static struct lock_file head_lock;
 878         struct strbuf buf = STRBUF_INIT;
 879         int fd;
 880
 881         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 882         strbuf_addf(&buf, "%s\n", head);
 883         if (write_in_full(fd, buf.buf, buf.len) < 0)
 884                 die_errno(_("Could not write to %s"), head_file);
 885         if (commit_lock_file(&head_lock) < 0)
 886                 die(_("Error wrapping up %s."), head_file);
 887 }
 888
 889 static int reset_for_rollback(const unsigned char *sha1)
 890 {
 891         const char *argv[4];    /* reset --merge <arg> + NULL */
 892         argv[0] = "reset";
 893         argv[1] = "--merge";
 894         argv[2] = sha1_to_hex(sha1);
 895         argv[3] = NULL;
 896         return run_command_v_opt(argv, RUN_GIT_CMD);
 897 }
 898
 899 static int rollback_single_pick(void)
 900 {
 901         unsigned char head_sha1[20];
 902
 903         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 904             !file_exists(git_path("REVERT_HEAD")))
 905                 return error(_("no cherry-pick or revert in progress"));
 906         if (!resolve_ref("HEAD", head_sha1, 0, NULL))
 907                 return error(_("cannot resolve HEAD"));
 908         if (is_null_sha1(head_sha1))
 909                 return error(_("cannot abort from a branch yet to be born"));
 910         return reset_for_rollback(head_sha1);
 911 }
 912
 913 static int sequencer_rollback(struct replay_opts *opts)
 914 {
 915         const char *filename;
 916         FILE *f;
 917         unsigned char sha1[20];
 918         struct strbuf buf = STRBUF_INIT;
 919
 920         filename = git_path(SEQ_HEAD_FILE);
 921         f = fopen(filename, "r");
 922         if (!f && errno == ENOENT) {
 923                 /*
 924                  * There is no multiple-cherry-pick in progress.
 925                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 926                  * a single-cherry-pick in progress, abort that.
 927                  */
 928                 return rollback_single_pick();
 929         }
 930         if (!f)
 931                 return error(_("cannot open %s: %s"), filename,
 932                                                 strerror(errno));
 933         if (strbuf_getline(&buf, f, '\n')) {
 934                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 935                         strerror(errno) : _("unexpected end of file"));
 936                 fclose(f);
 937                 goto fail;
 938         }
 939         fclose(f);
 940         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 941                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 942                         filename);
 943                 goto fail;
 944         }
 945         if (reset_for_rollback(sha1))
 946                 goto fail;
 947         remove_sequencer_state();
 948         strbuf_release(&buf);
 949         return 0;
 950 fail:
 951         strbuf_release(&buf);
 952         return -1;
 953 }
 954
 955 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 956 {
 957         const char *todo_file = git_path(SEQ_TODO_FILE);
 958         static struct lock_file todo_lock;
 959         struct strbuf buf = STRBUF_INIT;
 960         int fd;
 961
 962         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 963         if (format_todo(&buf, todo_list, opts) < 0)
 964                 die(_("Could not format %s."), todo_file);
 965         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 966                 strbuf_release(&buf);
 967                 die_errno(_("Could not write to %s"), todo_file);
 968         }
 969         if (commit_lock_file(&todo_lock) < 0) {
 970                 strbuf_release(&buf);
 971                 die(_("Error wrapping up %s."), todo_file);
 972         }
 973         strbuf_release(&buf);
 974 }
 975
 976 static void save_opts(struct replay_opts *opts)
 977 {
 978         const char *opts_file = git_path(SEQ_OPTS_FILE);
 979
 980         if (opts->no_commit)
 981                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 982         if (opts->edit)
 983                 git_config_set_in_file(opts_file, "options.edit", "true");
 984         if (opts->signoff)
 985                 git_config_set_in_file(opts_file, "options.signoff", "true");
 986         if (opts->record_origin)
 987                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 988         if (opts->allow_ff)
 989                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 990         if (opts->mainline) {
 991                 struct strbuf buf = STRBUF_INIT;
 992                 strbuf_addf(&buf, "%d", opts->mainline);
 993                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 994                 strbuf_release(&buf);
 995         }
 996         if (opts->strategy)
 997                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 998         if (opts->xopts) {
 999                 int i;
1000                 for (i = 0; i < opts->xopts_nr; i++)
1001                         git_config_set_multivar_in_file(opts_file,
1002                                                         "options.strategy-option",
1003                                                         opts->xopts[i], "^$", 0);
1004         }
1005 }
1006
1007 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
1008 {
1009         struct commit_list *cur;
1010         int res;
1011
1012         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1013         if (opts->allow_ff)
1014                 assert(!(opts->signoff || opts->no_commit ||
1015                                 opts->record_origin || opts->edit));
1016         read_and_refresh_cache(opts);
1017
1018         for (cur = todo_list; cur; cur = cur->next) {
1019                 save_todo(cur, opts);
1020                 res = do_pick_commit(cur->item, opts);
1021                 if (res)
1022                         return res;
1023         }
1024
1025         /*
1026          * Sequence of picks finished successfully; cleanup by
1027          * removing the .git/sequencer directory
1028          */
1029         remove_sequencer_state();
1030         return 0;
1031 }
1032
1033 static int continue_single_pick(void)
1034 {
1035         const char *argv[] = { "commit", NULL };
1036
1037         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
1038             !file_exists(git_path("REVERT_HEAD")))
1039                 return error(_("no cherry-pick or revert in progress"));
1040         return run_command_v_opt(argv, RUN_GIT_CMD);
1041 }
1042
1043 static int sequencer_continue(struct replay_opts *opts)
1044 {
1045         struct commit_list *todo_list = NULL;
1046
1047         if (!file_exists(git_path(SEQ_TODO_FILE)))
1048                 return continue_single_pick();
1049         read_populate_opts(&opts);
1050         read_populate_todo(&todo_list, opts);
1051
1052         /* Verify that the conflict has been resolved */
1053         if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
1054             file_exists(git_path("REVERT_HEAD"))) {
1055                 int ret = continue_single_pick();
1056                 if (ret)
1057                         return ret;
1058         }
1059         if (index_differs_from("HEAD", 0))
1060                 return error_dirty_index(opts);
1061         todo_list = todo_list->next;
1062         return pick_commits(todo_list, opts);
1063 }
1064
1065 static int single_pick(struct commit *cmit, struct replay_opts *opts)
1066 {
1067         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1068         return do_pick_commit(cmit, opts);
1069 }
1070
1071 static int pick_revisions(struct replay_opts *opts)
1072 {
1073         struct commit_list *todo_list = NULL;
1074         unsigned char sha1[20];
1075
1076         if (opts->subcommand == REPLAY_NONE)
1077                 assert(opts->revs);
1078
1079         read_and_refresh_cache(opts);
1080
1081         /*
1082          * Decide what to do depending on the arguments; a fresh
1083          * cherry-pick should be handled differently from an existing
1084          * one that is being continued
1085          */
1086         if (opts->subcommand == REPLAY_REMOVE_STATE) {
1087                 remove_sequencer_state();
1088                 return 0;
1089         }
1090         if (opts->subcommand == REPLAY_ROLLBACK)
1091                 return sequencer_rollback(opts);
1092         if (opts->subcommand == REPLAY_CONTINUE)
1093                 return sequencer_continue(opts);
1094
1095         /*
1096          * If we were called as "git cherry-pick <commit>", just
1097          * cherry-pick/revert it, set CHERRY_PICK_HEAD /
1098          * REVERT_HEAD, and don't touch the sequencer state.
1099          * This means it is possible to cherry-pick in the middle
1100          * of a cherry-pick sequence.
1101          */
1102         if (opts->revs->cmdline.nr == 1 &&
1103             opts->revs->cmdline.rev->whence == REV_CMD_REV &&
1104             opts->revs->no_walk &&
1105             !opts->revs->cmdline.rev->flags) {
1106                 struct commit *cmit;
1107                 if (prepare_revision_walk(opts->revs))
1108                         die(_("revision walk setup failed"));
1109                 cmit = get_revision(opts->revs);
1110                 if (!cmit || get_revision(opts->revs))
1111                         die("BUG: expected exactly one commit from walk");
1112                 return single_pick(cmit, opts);
1113         }
1114
1115         /*
1116          * Start a new cherry-pick/ revert sequence; but
1117          * first, make sure that an existing one isn't in
1118          * progress
1119          */
1120
1121         walk_revs_populate_todo(&todo_list, opts);
1122         if (create_seq_dir() < 0)
1123                 return -1;
1124         if (get_sha1("HEAD", sha1)) {
1125                 if (opts->action == REVERT)
1126                         return error(_("Can't revert as initial commit"));
1127                 return error(_("Can't cherry-pick into empty head"));
1128         }
1129         save_head(sha1_to_hex(sha1));
1130         save_opts(opts);
1131         return pick_commits(todo_list, opts);
1132 }
1133
1134 int cmd_revert(int argc, const char **argv, const char *prefix)
1135 {
1136         struct replay_opts opts;
1137         int res;
1138
1139         memset(&opts, 0, sizeof(opts));
1140         if (isatty(0))
1141                 opts.edit = 1;
1142         opts.action = REVERT;
1143         git_config(git_default_config, NULL);
1144         parse_args(argc, argv, &opts);
1145         res = pick_revisions(&opts);
1146         if (res < 0)
1147                 die(_("revert failed"));
1148         return res;
1149 }
1150
1151 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1152 {
1153         struct replay_opts opts;
1154         int res;
1155
1156         memset(&opts, 0, sizeof(opts));
1157         opts.action = CHERRY_PICK;
1158         git_config(git_default_config, NULL);
1159         parse_args(argc, argv, &opts);
1160         res = pick_revisions(&opts);
1161         if (res < 0)
1162                 die(_("cherry-pick failed"));
1163         return res;
1164 }