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