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_subcommand {
  43         REPLAY_NONE,
  44         REPLAY_REMOVE_STATE,
  45         REPLAY_CONTINUE,
  46         REPLAY_ROLLBACK
  47 };
  48
  49 struct replay_opts {
  50         enum replay_action action;
  51         enum replay_subcommand subcommand;
  52
  53         /* Boolean options */
  54         int edit;
  55         int record_origin;
  56         int no_commit;
  57         int signoff;
  58         int allow_ff;
  59         int allow_rerere_auto;
  60
  61         int mainline;
  62
  63         /* Merge strategy */
  64         const char *strategy;
  65         const char **xopts;
  66         size_t xopts_nr, xopts_alloc;
  67
  68         /* Only used by REPLAY_NONE */
  69         struct rev_info *revs;
  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 == REPLAY_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 == REPLAY_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
 133         if (opt1 && opt2)
 134                 die(_("%s: %s cannot be used with %s"), me, opt1, opt2);
 135 }
 136
 137 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 138 {
 139         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
 140         const char *me = action_name(opts);
 141         int remove_state = 0;
 142         int contin = 0;
 143         int rollback = 0;
 144         struct option options[] = {
 145                 OPT_BOOLEAN(0, "quit", &remove_state, "end revert or cherry-pick sequence"),
 146                 OPT_BOOLEAN(0, "continue", &contin, "resume revert or cherry-pick sequence"),
 147                 OPT_BOOLEAN(0, "abort", &rollback, "cancel revert or cherry-pick sequence"),
 148                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
 149                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
 150                 OPT_NOOP_NOARG('r', NULL),
 151                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
 152                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
 153                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
 154                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
 155                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
 156                         "option for merge strategy", option_parse_x),
 157                 OPT_END(),
 158                 OPT_END(),
 159                 OPT_END(),
 160         };
 161
 162         if (opts->action == REPLAY_PICK) {
 163                 struct option cp_extra[] = {
 164                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 165                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
 166                         OPT_END(),
 167                 };
 168                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
 169                         die(_("program error"));
 170         }
 171
 172         argc = parse_options(argc, argv, NULL, options, usage_str,
 173                         PARSE_OPT_KEEP_ARGV0 |
 174                         PARSE_OPT_KEEP_UNKNOWN);
 175
 176         /* Check for incompatible subcommands */
 177         verify_opt_mutually_compatible(me,
 178                                 "--quit", remove_state,
 179                                 "--continue", contin,
 180                                 "--abort", rollback,
 181                                 NULL);
 182
 183         /* Set the subcommand */
 184         if (remove_state)
 185                 opts->subcommand = REPLAY_REMOVE_STATE;
 186         else if (contin)
 187                 opts->subcommand = REPLAY_CONTINUE;
 188         else if (rollback)
 189                 opts->subcommand = REPLAY_ROLLBACK;
 190         else
 191                 opts->subcommand = REPLAY_NONE;
 192
 193         /* Check for incompatible command line arguments */
 194         if (opts->subcommand != REPLAY_NONE) {
 195                 char *this_operation;
 196                 if (opts->subcommand == REPLAY_REMOVE_STATE)
 197                         this_operation = "--quit";
 198                 else if (opts->subcommand == REPLAY_CONTINUE)
 199                         this_operation = "--continue";
 200                 else {
 201                         assert(opts->subcommand == REPLAY_ROLLBACK);
 202                         this_operation = "--abort";
 203                 }
 204
 205                 verify_opt_compatible(me, this_operation,
 206                                 "--no-commit", opts->no_commit,
 207                                 "--signoff", opts->signoff,
 208                                 "--mainline", opts->mainline,
 209                                 "--strategy", opts->strategy ? 1 : 0,
 210                                 "--strategy-option", opts->xopts ? 1 : 0,
 211                                 "-x", opts->record_origin,
 212                                 "--ff", opts->allow_ff,
 213                                 NULL);
 214         }
 215
 216         if (opts->allow_ff)
 217                 verify_opt_compatible(me, "--ff",
 218                                 "--signoff", opts->signoff,
 219                                 "--no-commit", opts->no_commit,
 220                                 "-x", opts->record_origin,
 221                                 "--edit", opts->edit,
 222                                 NULL);
 223
 224         if (opts->subcommand == REPLAY_NONE) {
 225                 opts->revs = xmalloc(sizeof(*opts->revs));
 226                 init_revisions(opts->revs, NULL);
 227                 opts->revs->no_walk = 1;
 228                 if (argc < 2)
 229                         usage_with_options(usage_str, options);
 230                 argc = setup_revisions(argc, argv, opts->revs, NULL);
 231         } else
 232                 opts->revs = NULL;
 233
 234         /* Forbid stray command-line arguments */
 235         if (argc > 1)
 236                 usage_with_options(usage_str, options);
 237 }
 238
 239 struct commit_message {
 240         char *parent_label;
 241         const char *label;
 242         const char *subject;
 243         char *reencoded_message;
 244         const char *message;
 245 };
 246
 247 static int get_message(struct commit *commit, struct commit_message *out)
 248 {
 249         const char *encoding;
 250         const char *abbrev, *subject;
 251         int abbrev_len, subject_len;
 252         char *q;
 253
 254         if (!commit->buffer)
 255                 return -1;
 256         encoding = get_encoding(commit->buffer);
 257         if (!encoding)
 258                 encoding = "UTF-8";
 259         if (!git_commit_encoding)
 260                 git_commit_encoding = "UTF-8";
 261
 262         out->reencoded_message = NULL;
 263         out->message = commit->buffer;
 264         if (strcmp(encoding, git_commit_encoding))
 265                 out->reencoded_message = reencode_string(commit->buffer,
 266                                         git_commit_encoding, encoding);
 267         if (out->reencoded_message)
 268                 out->message = out->reencoded_message;
 269
 270         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 271         abbrev_len = strlen(abbrev);
 272
 273         subject_len = find_commit_subject(out->message, &subject);
 274
 275         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 276                               strlen("... ") + subject_len + 1);
 277         q = out->parent_label;
 278         q = mempcpy(q, "parent of ", strlen("parent of "));
 279         out->label = q;
 280         q = mempcpy(q, abbrev, abbrev_len);
 281         q = mempcpy(q, "... ", strlen("... "));
 282         out->subject = q;
 283         q = mempcpy(q, subject, subject_len);
 284         *q = '\0';
 285         return 0;
 286 }
 287
 288 static void free_message(struct commit_message *msg)
 289 {
 290         free(msg->parent_label);
 291         free(msg->reencoded_message);
 292 }
 293
 294 static char *get_encoding(const char *message)
 295 {
 296         const char *p = message, *eol;
 297
 298         while (*p && *p != '\n') {
 299                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 300                         ; /* do nothing */
 301                 if (!prefixcmp(p, "encoding ")) {
 302                         char *result = xmalloc(eol - 8 - p);
 303                         strlcpy(result, p + 9, eol - 8 - p);
 304                         return result;
 305                 }
 306                 p = eol;
 307                 if (*p == '\n')
 308                         p++;
 309         }
 310         return NULL;
 311 }
 312
 313 static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
 314 {
 315         const char *filename;
 316         int fd;
 317         struct strbuf buf = STRBUF_INIT;
 318
 319         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 320
 321         filename = git_path("%s", pseudoref);
 322         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 323         if (fd < 0)
 324                 die_errno(_("Could not open '%s' for writing"), filename);
 325         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 326                 die_errno(_("Could not write to '%s'"), filename);
 327         strbuf_release(&buf);
 328 }
 329
 330 static void print_advice(int show_hint)
 331 {
 332         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 333
 334         if (msg) {
 335                 fprintf(stderr, "%s\n", msg);
 336                 /*
 337                  * A conflict has occured but the porcelain
 338                  * (typically rebase --interactive) wants to take care
 339                  * of the commit itself so remove CHERRY_PICK_HEAD
 340                  */
 341                 unlink(git_path("CHERRY_PICK_HEAD"));
 342                 return;
 343         }
 344
 345         if (show_hint) {
 346                 advise("after resolving the conflicts, mark the corrected paths");
 347                 advise("with 'git add <paths>' or 'git rm <paths>'");
 348                 advise("and commit the result with 'git commit'");
 349         }
 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 == REPLAY_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, enum replay_action action,
 481                         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 (action == REPLAY_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") || action == REPLAY_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 == REPLAY_PICK && !opts->no_commit && (res == 0 || res == 1))
 622                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 623         if (opts->action == REPLAY_REVERT && ((opts->no_commit && res == 0) || res == 1))
 624                 write_cherry_pick_head(commit, "REVERT_HEAD");
 625
 626         if (res) {
 627                 error(action == REPLAY_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 != REPLAY_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 replay_insn_list **replay_insn_list_append(enum replay_action action,
 690                                                 struct commit *operand,
 691                                                 struct replay_insn_list **next)
 692 {
 693         struct replay_insn_list *new = xmalloc(sizeof(*new));
 694         new->action = action;
 695         new->operand = operand;
 696         *next = new;
 697         new->next = NULL;
 698         return &new->next;
 699 }
 700
 701 static int format_todo(struct strbuf *buf, struct replay_insn_list *todo_list)
 702 {
 703         struct replay_insn_list *cur;
 704
 705         for (cur = todo_list; cur; cur = cur->next) {
 706                 const char *sha1_abbrev, *action_str, *subject;
 707                 int subject_len;
 708
 709                 action_str = cur->action == REPLAY_REVERT ? "revert" : "pick";
 710                 sha1_abbrev = find_unique_abbrev(cur->operand->object.sha1, DEFAULT_ABBREV);
 711                 subject_len = find_commit_subject(cur->operand->buffer, &subject);
 712                 strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
 713                         subject_len, subject);
 714         }
 715         return 0;
 716 }
 717
 718 static int parse_insn_line(char *bol, char *eol, struct replay_insn_list *item)
 719 {
 720         unsigned char commit_sha1[20];
 721         char *end_of_object_name;
 722         int saved, status;
 723
 724         if (!prefixcmp(bol, "pick ")) {
 725                 item->action = REPLAY_PICK;
 726                 bol += strlen("pick ");
 727         } else if (!prefixcmp(bol, "revert ")) {
 728                 item->action = REPLAY_REVERT;
 729                 bol += strlen("revert ");
 730         } else {
 731                 size_t len = strchrnul(bol, '\n') - bol;
 732                 if (len > 255)
 733                         len = 255;
 734                 return error(_("Unrecognized action: %.*s"), (int)len, bol);
 735         }
 736
 737         end_of_object_name = bol + strcspn(bol, " \n");
 738         saved = *end_of_object_name;
 739         *end_of_object_name = '\0';
 740         status = get_sha1(bol, commit_sha1);
 741         *end_of_object_name = saved;
 742
 743         if (status < 0)
 744                 return error(_("Malformed object name: %s"), bol);
 745
 746         item->operand = lookup_commit_reference(commit_sha1);
 747         if (!item->operand)
 748                 return error(_("Not a valid commit: %s"), bol);
 749
 750         item->next = NULL;
 751         return 0;
 752 }
 753
 754 static int parse_insn_buffer(char *buf, struct replay_insn_list **todo_list)
 755 {
 756         struct replay_insn_list **next = todo_list;
 757         struct replay_insn_list item = {0, NULL, NULL};
 758         char *p = buf;
 759         int i;
 760
 761         for (i = 1; *p; i++) {
 762                 char *eol = strchrnul(p, '\n');
 763                 if (parse_insn_line(p, eol, &item) < 0)
 764                         return error(_("on line %d."), i);
 765                 next = replay_insn_list_append(item.action, item.operand, next);
 766                 p = *eol ? eol + 1 : eol;
 767         }
 768         if (!*todo_list)
 769                 return error(_("No commits parsed."));
 770         return 0;
 771 }
 772
 773 static void read_populate_todo(struct replay_insn_list **todo_list)
 774 {
 775         const char *todo_file = git_path(SEQ_TODO_FILE);
 776         struct strbuf buf = STRBUF_INIT;
 777         int fd, res;
 778
 779         fd = open(todo_file, O_RDONLY);
 780         if (fd < 0)
 781                 die_errno(_("Could not open %s"), todo_file);
 782         if (strbuf_read(&buf, fd, 0) < 0) {
 783                 close(fd);
 784                 strbuf_release(&buf);
 785                 die(_("Could not read %s."), todo_file);
 786         }
 787         close(fd);
 788
 789         res = parse_insn_buffer(buf.buf, todo_list);
 790         strbuf_release(&buf);
 791         if (res)
 792                 die(_("Unusable instruction sheet: %s"), todo_file);
 793 }
 794
 795 static int populate_opts_cb(const char *key, const char *value, void *data)
 796 {
 797         struct replay_opts *opts = data;
 798         int error_flag = 1;
 799
 800         if (!value)
 801                 error_flag = 0;
 802         else if (!strcmp(key, "options.no-commit"))
 803                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 804         else if (!strcmp(key, "options.edit"))
 805                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 806         else if (!strcmp(key, "options.signoff"))
 807                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 808         else if (!strcmp(key, "options.record-origin"))
 809                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 810         else if (!strcmp(key, "options.allow-ff"))
 811                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 812         else if (!strcmp(key, "options.mainline"))
 813                 opts->mainline = git_config_int(key, value);
 814         else if (!strcmp(key, "options.strategy"))
 815                 git_config_string(&opts->strategy, key, value);
 816         else if (!strcmp(key, "options.strategy-option")) {
 817                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 818                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 819         } else
 820                 return error(_("Invalid key: %s"), key);
 821
 822         if (!error_flag)
 823                 return error(_("Invalid value for %s: %s"), key, value);
 824
 825         return 0;
 826 }
 827
 828 static void read_populate_opts(struct replay_opts **opts_ptr)
 829 {
 830         const char *opts_file = git_path(SEQ_OPTS_FILE);
 831
 832         if (!file_exists(opts_file))
 833                 return;
 834         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 835                 die(_("Malformed options sheet: %s"), opts_file);
 836 }
 837
 838 static void walk_revs_populate_todo(struct replay_insn_list **todo_list,
 839                                 struct replay_opts *opts)
 840 {
 841         struct commit *commit;
 842         struct replay_insn_list **next;
 843
 844         prepare_revs(opts);
 845
 846         next = todo_list;
 847         while ((commit = get_revision(opts->revs)))
 848                 next = replay_insn_list_append(opts->action, commit, next);
 849 }
 850
 851 static int create_seq_dir(void)
 852 {
 853         const char *seq_dir = git_path(SEQ_DIR);
 854
 855         if (file_exists(seq_dir)) {
 856                 error(_("a cherry-pick or revert is already in progress"));
 857                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 858                 return -1;
 859         }
 860         else if (mkdir(seq_dir, 0777) < 0)
 861                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 862         return 0;
 863 }
 864
 865 static void save_head(const char *head)
 866 {
 867         const char *head_file = git_path(SEQ_HEAD_FILE);
 868         static struct lock_file head_lock;
 869         struct strbuf buf = STRBUF_INIT;
 870         int fd;
 871
 872         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 873         strbuf_addf(&buf, "%s\n", head);
 874         if (write_in_full(fd, buf.buf, buf.len) < 0)
 875                 die_errno(_("Could not write to %s"), head_file);
 876         if (commit_lock_file(&head_lock) < 0)
 877                 die(_("Error wrapping up %s."), head_file);
 878 }
 879
 880 static int reset_for_rollback(const unsigned char *sha1)
 881 {
 882         const char *argv[4];    /* reset --merge <arg> + NULL */
 883         argv[0] = "reset";
 884         argv[1] = "--merge";
 885         argv[2] = sha1_to_hex(sha1);
 886         argv[3] = NULL;
 887         return run_command_v_opt(argv, RUN_GIT_CMD);
 888 }
 889
 890 static int rollback_single_pick(void)
 891 {
 892         unsigned char head_sha1[20];
 893
 894         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 895             !file_exists(git_path("REVERT_HEAD")))
 896                 return error(_("no cherry-pick or revert in progress"));
 897         if (!resolve_ref("HEAD", head_sha1, 0, NULL))
 898                 return error(_("cannot resolve HEAD"));
 899         if (is_null_sha1(head_sha1))
 900                 return error(_("cannot abort from a branch yet to be born"));
 901         return reset_for_rollback(head_sha1);
 902 }
 903
 904 static int sequencer_rollback(struct replay_opts *opts)
 905 {
 906         const char *filename;
 907         FILE *f;
 908         unsigned char sha1[20];
 909         struct strbuf buf = STRBUF_INIT;
 910
 911         filename = git_path(SEQ_HEAD_FILE);
 912         f = fopen(filename, "r");
 913         if (!f && errno == ENOENT) {
 914                 /*
 915                  * There is no multiple-cherry-pick in progress.
 916                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 917                  * a single-cherry-pick in progress, abort that.
 918                  */
 919                 return rollback_single_pick();
 920         }
 921         if (!f)
 922                 return error(_("cannot open %s: %s"), filename,
 923                                                 strerror(errno));
 924         if (strbuf_getline(&buf, f, '\n')) {
 925                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 926                         strerror(errno) : _("unexpected end of file"));
 927                 fclose(f);
 928                 goto fail;
 929         }
 930         fclose(f);
 931         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 932                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 933                         filename);
 934                 goto fail;
 935         }
 936         if (reset_for_rollback(sha1))
 937                 goto fail;
 938         remove_sequencer_state(1);
 939         strbuf_release(&buf);
 940         return 0;
 941 fail:
 942         strbuf_release(&buf);
 943         return -1;
 944 }
 945
 946 static void save_todo(struct replay_insn_list *todo_list)
 947 {
 948         const char *todo_file = git_path(SEQ_TODO_FILE);
 949         static struct lock_file todo_lock;
 950         struct strbuf buf = STRBUF_INIT;
 951         int fd;
 952
 953         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 954         if (format_todo(&buf, todo_list) < 0)
 955                 die(_("Could not format %s."), todo_file);
 956         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 957                 strbuf_release(&buf);
 958                 die_errno(_("Could not write to %s"), todo_file);
 959         }
 960         if (commit_lock_file(&todo_lock) < 0) {
 961                 strbuf_release(&buf);
 962                 die(_("Error wrapping up %s."), todo_file);
 963         }
 964         strbuf_release(&buf);
 965 }
 966
 967 static void save_opts(struct replay_opts *opts)
 968 {
 969         const char *opts_file = git_path(SEQ_OPTS_FILE);
 970
 971         if (opts->no_commit)
 972                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 973         if (opts->edit)
 974                 git_config_set_in_file(opts_file, "options.edit", "true");
 975         if (opts->signoff)
 976                 git_config_set_in_file(opts_file, "options.signoff", "true");
 977         if (opts->record_origin)
 978                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 979         if (opts->allow_ff)
 980                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 981         if (opts->mainline) {
 982                 struct strbuf buf = STRBUF_INIT;
 983                 strbuf_addf(&buf, "%d", opts->mainline);
 984                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 985                 strbuf_release(&buf);
 986         }
 987         if (opts->strategy)
 988                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 989         if (opts->xopts) {
 990                 int i;
 991                 for (i = 0; i < opts->xopts_nr; i++)
 992                         git_config_set_multivar_in_file(opts_file,
 993                                                         "options.strategy-option",
 994                                                         opts->xopts[i], "^$", 0);
 995         }
 996 }
 997
 998 static int pick_commits(struct replay_insn_list *todo_list,
 999                         struct replay_opts *opts)
1000 {
1001         struct replay_insn_list *cur;
1002         int res;
1003
1004         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1005         if (opts->allow_ff)
1006                 assert(!(opts->signoff || opts->no_commit ||
1007                                 opts->record_origin || opts->edit));
1008         read_and_refresh_cache(opts);
1009
1010         for (cur = todo_list; cur; cur = cur->next) {
1011                 save_todo(cur);
1012                 res = do_pick_commit(cur->operand, cur->action, opts);
1013                 if (res) {
1014                         if (!cur->next)
1015                                 /*
1016                                  * An error was encountered while
1017                                  * picking the last commit; the
1018                                  * sequencer state is useless now --
1019                                  * the user simply needs to resolve
1020                                  * the conflict and commit
1021                                  */
1022                                 remove_sequencer_state(0);
1023                         return res;
1024                 }
1025         }
1026
1027         /*
1028          * Sequence of picks finished successfully; cleanup by
1029          * removing the .git/sequencer directory
1030          */
1031         remove_sequencer_state(1);
1032         return 0;
1033 }
1034
1035 static int pick_revisions(struct replay_opts *opts)
1036 {
1037         struct replay_insn_list *todo_list = NULL;
1038         unsigned char sha1[20];
1039
1040         if (opts->subcommand == REPLAY_NONE)
1041                 assert(opts->revs);
1042
1043         read_and_refresh_cache(opts);
1044
1045         /*
1046          * Decide what to do depending on the arguments; a fresh
1047          * cherry-pick should be handled differently from an existing
1048          * one that is being continued
1049          */
1050         if (opts->subcommand == REPLAY_REMOVE_STATE) {
1051                 remove_sequencer_state(1);
1052                 return 0;
1053         }
1054         if (opts->subcommand == REPLAY_ROLLBACK)
1055                 return sequencer_rollback(opts);
1056         if (opts->subcommand == REPLAY_CONTINUE) {
1057                 if (!file_exists(git_path(SEQ_TODO_FILE)))
1058                         return error(_("No %s in progress"), action_name(opts));
1059                 read_populate_opts(&opts);
1060                 read_populate_todo(&todo_list);
1061
1062                 /* Verify that the conflict has been resolved */
1063                 if (!index_differs_from("HEAD", 0))
1064                         todo_list = todo_list->next;
1065                 return pick_commits(todo_list, opts);
1066         }
1067
1068         /*
1069          * Start a new cherry-pick/ revert sequence; but
1070          * first, make sure that an existing one isn't in
1071          * progress
1072          */
1073
1074         walk_revs_populate_todo(&todo_list, opts);
1075         if (create_seq_dir() < 0)
1076                 return -1;
1077         if (get_sha1("HEAD", sha1)) {
1078                 if (opts->action == REPLAY_REVERT)
1079                         return error(_("Can't revert as initial commit"));
1080                 return error(_("Can't cherry-pick into empty head"));
1081         }
1082         save_head(sha1_to_hex(sha1));
1083         save_opts(opts);
1084         return pick_commits(todo_list, opts);
1085 }
1086
1087 int cmd_revert(int argc, const char **argv, const char *prefix)
1088 {
1089         struct replay_opts opts;
1090         int res;
1091
1092         memset(&opts, 0, sizeof(opts));
1093         if (isatty(0))
1094                 opts.edit = 1;
1095         opts.action = REPLAY_REVERT;
1096         git_config(git_default_config, NULL);
1097         parse_args(argc, argv, &opts);
1098         res = pick_revisions(&opts);
1099         if (res < 0)
1100                 die(_("revert failed"));
1101         return res;
1102 }
1103
1104 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1105 {
1106         struct replay_opts opts;
1107         int res;
1108
1109         memset(&opts, 0, sizeof(opts));
1110         opts.action = REPLAY_PICK;
1111         git_config(git_default_config, NULL);
1112         parse_args(argc, argv, &opts);
1113         res = pick_revisions(&opts);
1114         if (res < 0)
1115                 die(_("cherry-pick failed"));
1116         return res;
1117 }