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\n"
 348                          "with 'git add <paths>' or 'git rm <paths>'\n"
 349                          "and commit the result with 'git commit'"));
 350 }
 351
 352 static void write_message(struct strbuf *msgbuf, const char *filename)
 353 {
 354         static struct lock_file msg_file;
 355
 356         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 357                                                LOCK_DIE_ON_ERROR);
 358         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 359                 die_errno(_("Could not write to %s"), filename);
 360         strbuf_release(msgbuf);
 361         if (commit_lock_file(&msg_file) < 0)
 362                 die(_("Error wrapping up %s"), filename);
 363 }
 364
 365 static struct tree *empty_tree(void)
 366 {
 367         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 368 }
 369
 370 static int error_dirty_index(struct replay_opts *opts)
 371 {
 372         if (read_cache_unmerged())
 373                 return error_resolve_conflict(action_name(opts));
 374
 375         /* Different translation strings for cherry-pick and revert */
 376         if (opts->action == CHERRY_PICK)
 377                 error(_("Your local changes would be overwritten by cherry-pick."));
 378         else
 379                 error(_("Your local changes would be overwritten by revert."));
 380
 381         if (advice_commit_before_merge)
 382                 advise(_("Commit your changes or stash them to proceed."));
 383         return -1;
 384 }
 385
 386 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 387 {
 388         struct ref_lock *ref_lock;
 389
 390         read_cache();
 391         if (checkout_fast_forward(from, to))
 392                 exit(1); /* the callee should have complained already */
 393         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 394         return write_ref_sha1(ref_lock, to, "cherry-pick");
 395 }
 396
 397 static int do_recursive_merge(struct commit *base, struct commit *next,
 398                               const char *base_label, const char *next_label,
 399                               unsigned char *head, struct strbuf *msgbuf,
 400                               struct replay_opts *opts)
 401 {
 402         struct merge_options o;
 403         struct tree *result, *next_tree, *base_tree, *head_tree;
 404         int clean, index_fd;
 405         const char **xopt;
 406         static struct lock_file index_lock;
 407
 408         index_fd = hold_locked_index(&index_lock, 1);
 409
 410         read_cache();
 411
 412         init_merge_options(&o);
 413         o.ancestor = base ? base_label : "(empty tree)";
 414         o.branch1 = "HEAD";
 415         o.branch2 = next ? next_label : "(empty tree)";
 416
 417         head_tree = parse_tree_indirect(head);
 418         next_tree = next ? next->tree : empty_tree();
 419         base_tree = base ? base->tree : empty_tree();
 420
 421         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 422                 parse_merge_opt(&o, *xopt);
 423
 424         clean = merge_trees(&o,
 425                             head_tree,
 426                             next_tree, base_tree, &result);
 427
 428         if (active_cache_changed &&
 429             (write_cache(index_fd, active_cache, active_nr) ||
 430              commit_locked_index(&index_lock)))
 431                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 432                 die(_("%s: Unable to write new index file"), action_name(opts));
 433         rollback_lock_file(&index_lock);
 434
 435         if (!clean) {
 436                 int i;
 437                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 438                 for (i = 0; i < active_nr;) {
 439                         struct cache_entry *ce = active_cache[i++];
 440                         if (ce_stage(ce)) {
 441                                 strbuf_addch(msgbuf, '\t');
 442                                 strbuf_addstr(msgbuf, ce->name);
 443                                 strbuf_addch(msgbuf, '\n');
 444                                 while (i < active_nr && !strcmp(ce->name,
 445                                                 active_cache[i]->name))
 446                                         i++;
 447                         }
 448                 }
 449         }
 450
 451         return !clean;
 452 }
 453
 454 /*
 455  * If we are cherry-pick, and if the merge did not result in
 456  * hand-editing, we will hit this commit and inherit the original
 457  * author date and name.
 458  * If we are revert, or if our cherry-pick results in a hand merge,
 459  * we had better say that the current user is responsible for that.
 460  */
 461 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 462 {
 463         /* 6 is max possible length of our args array including NULL */
 464         const char *args[6];
 465         int i = 0;
 466
 467         args[i++] = "commit";
 468         args[i++] = "-n";
 469         if (opts->signoff)
 470                 args[i++] = "-s";
 471         if (!opts->edit) {
 472                 args[i++] = "-F";
 473                 args[i++] = defmsg;
 474         }
 475         args[i] = NULL;
 476
 477         return run_command_v_opt(args, RUN_GIT_CMD);
 478 }
 479
 480 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 481 {
 482         unsigned char head[20];
 483         struct commit *base, *next, *parent;
 484         const char *base_label, *next_label;
 485         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 486         char *defmsg = NULL;
 487         struct strbuf msgbuf = STRBUF_INIT;
 488         int res;
 489
 490         if (opts->no_commit) {
 491                 /*
 492                  * We do not intend to commit immediately.  We just want to
 493                  * merge the differences in, so let's compute the tree
 494                  * that represents the "current" state for merge-recursive
 495                  * to work on.
 496                  */
 497                 if (write_cache_as_tree(head, 0, NULL))
 498                         die (_("Your index file is unmerged."));
 499         } else {
 500                 if (get_sha1("HEAD", head))
 501                         return error(_("You do not have a valid HEAD"));
 502                 if (index_differs_from("HEAD", 0))
 503                         return error_dirty_index(opts);
 504         }
 505         discard_cache();
 506
 507         if (!commit->parents) {
 508                 parent = NULL;
 509         }
 510         else if (commit->parents->next) {
 511                 /* Reverting or cherry-picking a merge commit */
 512                 int cnt;
 513                 struct commit_list *p;
 514
 515                 if (!opts->mainline)
 516                         return error(_("Commit %s is a merge but no -m option was given."),
 517                                 sha1_to_hex(commit->object.sha1));
 518
 519                 for (cnt = 1, p = commit->parents;
 520                      cnt != opts->mainline && p;
 521                      cnt++)
 522                         p = p->next;
 523                 if (cnt != opts->mainline || !p)
 524                         return error(_("Commit %s does not have parent %d"),
 525                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 526                 parent = p->item;
 527         } else if (0 < opts->mainline)
 528                 return error(_("Mainline was specified but commit %s is not a merge."),
 529                         sha1_to_hex(commit->object.sha1));
 530         else
 531                 parent = commit->parents->item;
 532
 533         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 534                 return fast_forward_to(commit->object.sha1, head);
 535
 536         if (parent && parse_commit(parent) < 0)
 537                 /* TRANSLATORS: The first %s will be "revert" or
 538                    "cherry-pick", the second %s a SHA1 */
 539                 return error(_("%s: cannot parse parent commit %s"),
 540                         action_name(opts), sha1_to_hex(parent->object.sha1));
 541
 542         if (get_message(commit, &msg) != 0)
 543                 return error(_("Cannot get commit message for %s"),
 544                         sha1_to_hex(commit->object.sha1));
 545
 546         /*
 547          * "commit" is an existing commit.  We would want to apply
 548          * the difference it introduces since its first parent "prev"
 549          * on top of the current HEAD if we are cherry-pick.  Or the
 550          * reverse of it if we are revert.
 551          */
 552
 553         defmsg = git_pathdup("MERGE_MSG");
 554
 555         if (opts->action == REVERT) {
 556                 base = commit;
 557                 base_label = msg.label;
 558                 next = parent;
 559                 next_label = msg.parent_label;
 560                 strbuf_addstr(&msgbuf, "Revert \"");
 561                 strbuf_addstr(&msgbuf, msg.subject);
 562                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 563                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 564
 565                 if (commit->parents && commit->parents->next) {
 566                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 567                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 568                 }
 569                 strbuf_addstr(&msgbuf, ".\n");
 570         } else {
 571                 const char *p;
 572
 573                 base = parent;
 574                 base_label = msg.parent_label;
 575                 next = commit;
 576                 next_label = msg.label;
 577
 578                 /*
 579                  * Append the commit log message to msgbuf; it starts
 580                  * after the tree, parent, author, committer
 581                  * information followed by "\n\n".
 582                  */
 583                 p = strstr(msg.message, "\n\n");
 584                 if (p) {
 585                         p += 2;
 586                         strbuf_addstr(&msgbuf, p);
 587                 }
 588
 589                 if (opts->record_origin) {
 590                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 591                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 592                         strbuf_addstr(&msgbuf, ")\n");
 593                 }
 594         }
 595
 596         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
 597                 res = do_recursive_merge(base, next, base_label, next_label,
 598                                          head, &msgbuf, opts);
 599                 write_message(&msgbuf, defmsg);
 600         } else {
 601                 struct commit_list *common = NULL;
 602                 struct commit_list *remotes = NULL;
 603
 604                 write_message(&msgbuf, defmsg);
 605
 606                 commit_list_insert(base, &common);
 607                 commit_list_insert(next, &remotes);
 608                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 609                                         common, sha1_to_hex(head), remotes);
 610                 free_commit_list(common);
 611                 free_commit_list(remotes);
 612         }
 613
 614         /*
 615          * If the merge was clean or if it failed due to conflict, we write
 616          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 617          * However, if the merge did not even start, then we don't want to
 618          * write it at all.
 619          */
 620         if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
 621                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 622         if (opts->action == REVERT && ((opts->no_commit && res == 0) || res == 1))
 623                 write_cherry_pick_head(commit, "REVERT_HEAD");
 624
 625         if (res) {
 626                 error(opts->action == REVERT
 627                       ? _("could not revert %s... %s")
 628                       : _("could not apply %s... %s"),
 629                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 630                       msg.subject);
 631                 print_advice(res == 1);
 632                 rerere(opts->allow_rerere_auto);
 633         } else {
 634                 if (!opts->no_commit)
 635                         res = run_git_commit(defmsg, opts);
 636         }
 637
 638         free_message(&msg);
 639         free(defmsg);
 640
 641         return res;
 642 }
 643
 644 static void prepare_revs(struct replay_opts *opts)
 645 {
 646         if (opts->action != REVERT)
 647                 opts->revs->reverse ^= 1;
 648
 649         if (prepare_revision_walk(opts->revs))
 650                 die(_("revision walk setup failed"));
 651
 652         if (!opts->revs->commits)
 653                 die(_("empty commit set passed"));
 654 }
 655
 656 static void read_and_refresh_cache(struct replay_opts *opts)
 657 {
 658         static struct lock_file index_lock;
 659         int index_fd = hold_locked_index(&index_lock, 0);
 660         if (read_index_preload(&the_index, NULL) < 0)
 661                 die(_("git %s: failed to read the index"), action_name(opts));
 662         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 663         if (the_index.cache_changed) {
 664                 if (write_index(&the_index, index_fd) ||
 665                     commit_locked_index(&index_lock))
 666                         die(_("git %s: failed to refresh the index"), action_name(opts));
 667         }
 668         rollback_lock_file(&index_lock);
 669 }
 670
 671 /*
 672  * Append a commit to the end of the commit_list.
 673  *
 674  * next starts by pointing to the variable that holds the head of an
 675  * empty commit_list, and is updated to point to the "next" field of
 676  * the last item on the list as new commits are appended.
 677  *
 678  * Usage example:
 679  *
 680  *     struct commit_list *list;
 681  *     struct commit_list **next = &list;
 682  *
 683  *     next = commit_list_append(c1, next);
 684  *     next = commit_list_append(c2, next);
 685  *     assert(commit_list_count(list) == 2);
 686  *     return list;
 687  */
 688 static struct commit_list **commit_list_append(struct commit *commit,
 689                                                struct commit_list **next)
 690 {
 691         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 692         new->item = commit;
 693         *next = new;
 694         new->next = NULL;
 695         return &new->next;
 696 }
 697
 698 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 699                 struct replay_opts *opts)
 700 {
 701         struct commit_list *cur = NULL;
 702         const char *sha1_abbrev = NULL;
 703         const char *action_str = opts->action == REVERT ? "revert" : "pick";
 704         const char *subject;
 705         int subject_len;
 706
 707         for (cur = todo_list; cur; cur = cur->next) {
 708                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 709                 subject_len = find_commit_subject(cur->item->buffer, &subject);
 710                 strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
 711                         subject_len, subject);
 712         }
 713         return 0;
 714 }
 715
 716 static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
 717 {
 718         unsigned char commit_sha1[20];
 719         enum replay_action action;
 720         char *end_of_object_name;
 721         int saved, status, padding;
 722
 723         if (!prefixcmp(bol, "pick")) {
 724                 action = CHERRY_PICK;
 725                 bol += strlen("pick");
 726         } else if (!prefixcmp(bol, "revert")) {
 727                 action = REVERT;
 728                 bol += strlen("revert");
 729         } else
 730                 return NULL;
 731
 732         /* Eat up extra spaces/ tabs before object name */
 733         padding = strspn(bol, " \t");
 734         if (!padding)
 735                 return NULL;
 736         bol += padding;
 737
 738         end_of_object_name = bol + strcspn(bol, " \t\n");
 739         saved = *end_of_object_name;
 740         *end_of_object_name = '\0';
 741         status = get_sha1(bol, commit_sha1);
 742         *end_of_object_name = saved;
 743
 744         /*
 745          * Verify that the action matches up with the one in
 746          * opts; we don't support arbitrary instructions
 747          */
 748         if (action != opts->action) {
 749                 const char *action_str;
 750                 action_str = action == REVERT ? "revert" : "cherry-pick";
 751                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 752                 return NULL;
 753         }
 754
 755         if (status < 0)
 756                 return NULL;
 757
 758         return lookup_commit_reference(commit_sha1);
 759 }
 760
 761 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 762                         struct replay_opts *opts)
 763 {
 764         struct commit_list **next = todo_list;
 765         struct commit *commit;
 766         char *p = buf;
 767         int i;
 768
 769         for (i = 1; *p; i++) {
 770                 char *eol = strchrnul(p, '\n');
 771                 commit = parse_insn_line(p, eol, opts);
 772                 if (!commit)
 773                         return error(_("Could not parse line %d."), i);
 774                 next = commit_list_append(commit, next);
 775                 p = *eol ? eol + 1 : eol;
 776         }
 777         if (!*todo_list)
 778                 return error(_("No commits parsed."));
 779         return 0;
 780 }
 781
 782 static void read_populate_todo(struct commit_list **todo_list,
 783                         struct replay_opts *opts)
 784 {
 785         const char *todo_file = git_path(SEQ_TODO_FILE);
 786         struct strbuf buf = STRBUF_INIT;
 787         int fd, res;
 788
 789         fd = open(todo_file, O_RDONLY);
 790         if (fd < 0)
 791                 die_errno(_("Could not open %s"), todo_file);
 792         if (strbuf_read(&buf, fd, 0) < 0) {
 793                 close(fd);
 794                 strbuf_release(&buf);
 795                 die(_("Could not read %s."), todo_file);
 796         }
 797         close(fd);
 798
 799         res = parse_insn_buffer(buf.buf, todo_list, opts);
 800         strbuf_release(&buf);
 801         if (res)
 802                 die(_("Unusable instruction sheet: %s"), todo_file);
 803 }
 804
 805 static int populate_opts_cb(const char *key, const char *value, void *data)
 806 {
 807         struct replay_opts *opts = data;
 808         int error_flag = 1;
 809
 810         if (!value)
 811                 error_flag = 0;
 812         else if (!strcmp(key, "options.no-commit"))
 813                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 814         else if (!strcmp(key, "options.edit"))
 815                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 816         else if (!strcmp(key, "options.signoff"))
 817                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 818         else if (!strcmp(key, "options.record-origin"))
 819                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 820         else if (!strcmp(key, "options.allow-ff"))
 821                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 822         else if (!strcmp(key, "options.mainline"))
 823                 opts->mainline = git_config_int(key, value);
 824         else if (!strcmp(key, "options.strategy"))
 825                 git_config_string(&opts->strategy, key, value);
 826         else if (!strcmp(key, "options.strategy-option")) {
 827                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 828                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 829         } else
 830                 return error(_("Invalid key: %s"), key);
 831
 832         if (!error_flag)
 833                 return error(_("Invalid value for %s: %s"), key, value);
 834
 835         return 0;
 836 }
 837
 838 static void read_populate_opts(struct replay_opts **opts_ptr)
 839 {
 840         const char *opts_file = git_path(SEQ_OPTS_FILE);
 841
 842         if (!file_exists(opts_file))
 843                 return;
 844         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 845                 die(_("Malformed options sheet: %s"), opts_file);
 846 }
 847
 848 static void walk_revs_populate_todo(struct commit_list **todo_list,
 849                                 struct replay_opts *opts)
 850 {
 851         struct commit *commit;
 852         struct commit_list **next;
 853
 854         prepare_revs(opts);
 855
 856         next = todo_list;
 857         while ((commit = get_revision(opts->revs)))
 858                 next = commit_list_append(commit, next);
 859 }
 860
 861 static int create_seq_dir(void)
 862 {
 863         const char *seq_dir = git_path(SEQ_DIR);
 864
 865         if (file_exists(seq_dir)) {
 866                 error(_("a cherry-pick or revert is already in progress"));
 867                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 868                 return -1;
 869         }
 870         else if (mkdir(seq_dir, 0777) < 0)
 871                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 872         return 0;
 873 }
 874
 875 static void save_head(const char *head)
 876 {
 877         const char *head_file = git_path(SEQ_HEAD_FILE);
 878         static struct lock_file head_lock;
 879         struct strbuf buf = STRBUF_INIT;
 880         int fd;
 881
 882         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 883         strbuf_addf(&buf, "%s\n", head);
 884         if (write_in_full(fd, buf.buf, buf.len) < 0)
 885                 die_errno(_("Could not write to %s"), head_file);
 886         if (commit_lock_file(&head_lock) < 0)
 887                 die(_("Error wrapping up %s."), head_file);
 888 }
 889
 890 static int reset_for_rollback(const unsigned char *sha1)
 891 {
 892         const char *argv[4];    /* reset --merge <arg> + NULL */
 893         argv[0] = "reset";
 894         argv[1] = "--merge";
 895         argv[2] = sha1_to_hex(sha1);
 896         argv[3] = NULL;
 897         return run_command_v_opt(argv, RUN_GIT_CMD);
 898 }
 899
 900 static int rollback_single_pick(void)
 901 {
 902         unsigned char head_sha1[20];
 903
 904         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 905             !file_exists(git_path("REVERT_HEAD")))
 906                 return error(_("no cherry-pick or revert in progress"));
 907         if (read_ref_full("HEAD", head_sha1, 0, NULL))
 908                 return error(_("cannot resolve HEAD"));
 909         if (is_null_sha1(head_sha1))
 910                 return error(_("cannot abort from a branch yet to be born"));
 911         return reset_for_rollback(head_sha1);
 912 }
 913
 914 static int sequencer_rollback(struct replay_opts *opts)
 915 {
 916         const char *filename;
 917         FILE *f;
 918         unsigned char sha1[20];
 919         struct strbuf buf = STRBUF_INIT;
 920
 921         filename = git_path(SEQ_HEAD_FILE);
 922         f = fopen(filename, "r");
 923         if (!f && errno == ENOENT) {
 924                 /*
 925                  * There is no multiple-cherry-pick in progress.
 926                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 927                  * a single-cherry-pick in progress, abort that.
 928                  */
 929                 return rollback_single_pick();
 930         }
 931         if (!f)
 932                 return error(_("cannot open %s: %s"), filename,
 933                                                 strerror(errno));
 934         if (strbuf_getline(&buf, f, '\n')) {
 935                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 936                         strerror(errno) : _("unexpected end of file"));
 937                 fclose(f);
 938                 goto fail;
 939         }
 940         fclose(f);
 941         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 942                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 943                         filename);
 944                 goto fail;
 945         }
 946         if (reset_for_rollback(sha1))
 947                 goto fail;
 948         remove_sequencer_state();
 949         strbuf_release(&buf);
 950         return 0;
 951 fail:
 952         strbuf_release(&buf);
 953         return -1;
 954 }
 955
 956 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 957 {
 958         const char *todo_file = git_path(SEQ_TODO_FILE);
 959         static struct lock_file todo_lock;
 960         struct strbuf buf = STRBUF_INIT;
 961         int fd;
 962
 963         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 964         if (format_todo(&buf, todo_list, opts) < 0)
 965                 die(_("Could not format %s."), todo_file);
 966         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 967                 strbuf_release(&buf);
 968                 die_errno(_("Could not write to %s"), todo_file);
 969         }
 970         if (commit_lock_file(&todo_lock) < 0) {
 971                 strbuf_release(&buf);
 972                 die(_("Error wrapping up %s."), todo_file);
 973         }
 974         strbuf_release(&buf);
 975 }
 976
 977 static void save_opts(struct replay_opts *opts)
 978 {
 979         const char *opts_file = git_path(SEQ_OPTS_FILE);
 980
 981         if (opts->no_commit)
 982                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 983         if (opts->edit)
 984                 git_config_set_in_file(opts_file, "options.edit", "true");
 985         if (opts->signoff)
 986                 git_config_set_in_file(opts_file, "options.signoff", "true");
 987         if (opts->record_origin)
 988                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 989         if (opts->allow_ff)
 990                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 991         if (opts->mainline) {
 992                 struct strbuf buf = STRBUF_INIT;
 993                 strbuf_addf(&buf, "%d", opts->mainline);
 994                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 995                 strbuf_release(&buf);
 996         }
 997         if (opts->strategy)
 998                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 999         if (opts->xopts) {
1000                 int i;
1001                 for (i = 0; i < opts->xopts_nr; i++)
1002                         git_config_set_multivar_in_file(opts_file,
1003                                                         "options.strategy-option",
1004                                                         opts->xopts[i], "^$", 0);
1005         }
1006 }
1007
1008 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
1009 {
1010         struct commit_list *cur;
1011         int res;
1012
1013         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1014         if (opts->allow_ff)
1015                 assert(!(opts->signoff || opts->no_commit ||
1016                                 opts->record_origin || opts->edit));
1017         read_and_refresh_cache(opts);
1018
1019         for (cur = todo_list; cur; cur = cur->next) {
1020                 save_todo(cur, opts);
1021                 res = do_pick_commit(cur->item, opts);
1022                 if (res)
1023                         return res;
1024         }
1025
1026         /*
1027          * Sequence of picks finished successfully; cleanup by
1028          * removing the .git/sequencer directory
1029          */
1030         remove_sequencer_state();
1031         return 0;
1032 }
1033
1034 static int continue_single_pick(void)
1035 {
1036         const char *argv[] = { "commit", NULL };
1037
1038         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
1039             !file_exists(git_path("REVERT_HEAD")))
1040                 return error(_("no cherry-pick or revert in progress"));
1041         return run_command_v_opt(argv, RUN_GIT_CMD);
1042 }
1043
1044 static int sequencer_continue(struct replay_opts *opts)
1045 {
1046         struct commit_list *todo_list = NULL;
1047
1048         if (!file_exists(git_path(SEQ_TODO_FILE)))
1049                 return continue_single_pick();
1050         read_populate_opts(&opts);
1051         read_populate_todo(&todo_list, opts);
1052
1053         /* Verify that the conflict has been resolved */
1054         if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
1055             file_exists(git_path("REVERT_HEAD"))) {
1056                 int ret = continue_single_pick();
1057                 if (ret)
1058                         return ret;
1059         }
1060         if (index_differs_from("HEAD", 0))
1061                 return error_dirty_index(opts);
1062         todo_list = todo_list->next;
1063         return pick_commits(todo_list, opts);
1064 }
1065
1066 static int single_pick(struct commit *cmit, struct replay_opts *opts)
1067 {
1068         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1069         return do_pick_commit(cmit, opts);
1070 }
1071
1072 static int pick_revisions(struct replay_opts *opts)
1073 {
1074         struct commit_list *todo_list = NULL;
1075         unsigned char sha1[20];
1076
1077         if (opts->subcommand == REPLAY_NONE)
1078                 assert(opts->revs);
1079
1080         read_and_refresh_cache(opts);
1081
1082         /*
1083          * Decide what to do depending on the arguments; a fresh
1084          * cherry-pick should be handled differently from an existing
1085          * one that is being continued
1086          */
1087         if (opts->subcommand == REPLAY_REMOVE_STATE) {
1088                 remove_sequencer_state();
1089                 return 0;
1090         }
1091         if (opts->subcommand == REPLAY_ROLLBACK)
1092                 return sequencer_rollback(opts);
1093         if (opts->subcommand == REPLAY_CONTINUE)
1094                 return sequencer_continue(opts);
1095
1096         /*
1097          * If we were called as "git cherry-pick <commit>", just
1098          * cherry-pick/revert it, set CHERRY_PICK_HEAD /
1099          * REVERT_HEAD, and don't touch the sequencer state.
1100          * This means it is possible to cherry-pick in the middle
1101          * of a cherry-pick sequence.
1102          */
1103         if (opts->revs->cmdline.nr == 1 &&
1104             opts->revs->cmdline.rev->whence == REV_CMD_REV &&
1105             opts->revs->no_walk &&
1106             !opts->revs->cmdline.rev->flags) {
1107                 struct commit *cmit;
1108                 if (prepare_revision_walk(opts->revs))
1109                         die(_("revision walk setup failed"));
1110                 cmit = get_revision(opts->revs);
1111                 if (!cmit || get_revision(opts->revs))
1112                         die("BUG: expected exactly one commit from walk");
1113                 return single_pick(cmit, opts);
1114         }
1115
1116         /*
1117          * Start a new cherry-pick/ revert sequence; but
1118          * first, make sure that an existing one isn't in
1119          * progress
1120          */
1121
1122         walk_revs_populate_todo(&todo_list, opts);
1123         if (create_seq_dir() < 0)
1124                 return -1;
1125         if (get_sha1("HEAD", sha1)) {
1126                 if (opts->action == REVERT)
1127                         return error(_("Can't revert as initial commit"));
1128                 return error(_("Can't cherry-pick into empty head"));
1129         }
1130         save_head(sha1_to_hex(sha1));
1131         save_opts(opts);
1132         return pick_commits(todo_list, opts);
1133 }
1134
1135 int cmd_revert(int argc, const char **argv, const char *prefix)
1136 {
1137         struct replay_opts opts;
1138         int res;
1139
1140         memset(&opts, 0, sizeof(opts));
1141         if (isatty(0))
1142                 opts.edit = 1;
1143         opts.action = REVERT;
1144         git_config(git_default_config, NULL);
1145         parse_args(argc, argv, &opts);
1146         res = pick_revisions(&opts);
1147         if (res < 0)
1148                 die(_("revert failed"));
1149         return res;
1150 }
1151
1152 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1153 {
1154         struct replay_opts opts;
1155         int res;
1156
1157         memset(&opts, 0, sizeof(opts));
1158         opts.action = CHERRY_PICK;
1159         git_config(git_default_config, NULL);
1160         parse_args(argc, argv, &opts);
1161         res = pick_revisions(&opts);
1162         if (res < 0)
1163                 die(_("cherry-pick failed"));
1164         return res;
1165 }