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 {
  43         REPLAY_REVERT,
  44         REPLAY_PICK
  45 };
  46
  47 enum replay_subcommand {
  48         REPLAY_NONE,
  49         REPLAY_REMOVE_STATE,
  50         REPLAY_CONTINUE,
  51         REPLAY_ROLLBACK
  52 };
  53
  54 struct replay_opts {
  55         enum replay_action action;
  56         enum replay_subcommand subcommand;
  57
  58         /* Boolean options */
  59         int edit;
  60         int record_origin;
  61         int no_commit;
  62         int signoff;
  63         int allow_ff;
  64         int allow_rerere_auto;
  65
  66         int mainline;
  67
  68         /* Merge strategy */
  69         const char *strategy;
  70         const char **xopts;
  71         size_t xopts_nr, xopts_alloc;
  72
  73         /* Only used by REPLAY_NONE */
  74         struct rev_info *revs;
  75 };
  76
  77 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  78
  79 static const char *action_name(const struct replay_opts *opts)
  80 {
  81         return opts->action == REPLAY_REVERT ? "revert" : "cherry-pick";
  82 }
  83
  84 static char *get_encoding(const char *message);
  85
  86 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
  87 {
  88         return opts->action == REPLAY_REVERT ? revert_usage : cherry_pick_usage;
  89 }
  90
  91 static int option_parse_x(const struct option *opt,
  92                           const char *arg, int unset)
  93 {
  94         struct replay_opts **opts_ptr = opt->value;
  95         struct replay_opts *opts = *opts_ptr;
  96
  97         if (unset)
  98                 return 0;
  99
 100         ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 101         opts->xopts[opts->xopts_nr++] = xstrdup(arg);
 102         return 0;
 103 }
 104
 105 static void verify_opt_compatible(const char *me, const char *base_opt, ...)
 106 {
 107         const char *this_opt;
 108         va_list ap;
 109
 110         va_start(ap, base_opt);
 111         while ((this_opt = va_arg(ap, const char *))) {
 112                 if (va_arg(ap, int))
 113                         break;
 114         }
 115         va_end(ap);
 116
 117         if (this_opt)
 118                 die(_("%s: %s cannot be used with %s"), me, this_opt, base_opt);
 119 }
 120
 121 static void verify_opt_mutually_compatible(const char *me, ...)
 122 {
 123         const char *opt1, *opt2 = NULL;
 124         va_list ap;
 125
 126         va_start(ap, me);
 127         while ((opt1 = va_arg(ap, const char *))) {
 128                 if (va_arg(ap, int))
 129                         break;
 130         }
 131         if (opt1) {
 132                 while ((opt2 = va_arg(ap, const char *))) {
 133                         if (va_arg(ap, int))
 134                                 break;
 135                 }
 136         }
 137
 138         if (opt1 && opt2)
 139                 die(_("%s: %s cannot be used with %s"), me, opt1, opt2);
 140 }
 141
 142 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 143 {
 144         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
 145         const char *me = action_name(opts);
 146         int remove_state = 0;
 147         int contin = 0;
 148         int rollback = 0;
 149         struct option options[] = {
 150                 OPT_BOOLEAN(0, "quit", &remove_state, "end revert or cherry-pick sequence"),
 151                 OPT_BOOLEAN(0, "continue", &contin, "resume revert or cherry-pick sequence"),
 152                 OPT_BOOLEAN(0, "abort", &rollback, "cancel revert or cherry-pick sequence"),
 153                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
 154                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
 155                 OPT_NOOP_NOARG('r', NULL),
 156                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
 157                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
 158                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
 159                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
 160                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
 161                         "option for merge strategy", option_parse_x),
 162                 OPT_END(),
 163                 OPT_END(),
 164                 OPT_END(),
 165         };
 166
 167         if (opts->action == REPLAY_PICK) {
 168                 struct option cp_extra[] = {
 169                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 170                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
 171                         OPT_END(),
 172                 };
 173                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
 174                         die(_("program error"));
 175         }
 176
 177         argc = parse_options(argc, argv, NULL, options, usage_str,
 178                         PARSE_OPT_KEEP_ARGV0 |
 179                         PARSE_OPT_KEEP_UNKNOWN);
 180
 181         /* Check for incompatible subcommands */
 182         verify_opt_mutually_compatible(me,
 183                                 "--quit", remove_state,
 184                                 "--continue", contin,
 185                                 "--abort", rollback,
 186                                 NULL);
 187
 188         /* Set the subcommand */
 189         if (remove_state)
 190                 opts->subcommand = REPLAY_REMOVE_STATE;
 191         else if (contin)
 192                 opts->subcommand = REPLAY_CONTINUE;
 193         else if (rollback)
 194                 opts->subcommand = REPLAY_ROLLBACK;
 195         else
 196                 opts->subcommand = REPLAY_NONE;
 197
 198         /* Check for incompatible command line arguments */
 199         if (opts->subcommand != REPLAY_NONE) {
 200                 char *this_operation;
 201                 if (opts->subcommand == REPLAY_REMOVE_STATE)
 202                         this_operation = "--quit";
 203                 else if (opts->subcommand == REPLAY_CONTINUE)
 204                         this_operation = "--continue";
 205                 else {
 206                         assert(opts->subcommand == REPLAY_ROLLBACK);
 207                         this_operation = "--abort";
 208                 }
 209
 210                 verify_opt_compatible(me, this_operation,
 211                                 "--no-commit", opts->no_commit,
 212                                 "--signoff", opts->signoff,
 213                                 "--mainline", opts->mainline,
 214                                 "--strategy", opts->strategy ? 1 : 0,
 215                                 "--strategy-option", opts->xopts ? 1 : 0,
 216                                 "-x", opts->record_origin,
 217                                 "--ff", opts->allow_ff,
 218                                 NULL);
 219         }
 220
 221         if (opts->allow_ff)
 222                 verify_opt_compatible(me, "--ff",
 223                                 "--signoff", opts->signoff,
 224                                 "--no-commit", opts->no_commit,
 225                                 "-x", opts->record_origin,
 226                                 "--edit", opts->edit,
 227                                 NULL);
 228
 229         if (opts->subcommand != REPLAY_NONE) {
 230                 opts->revs = NULL;
 231         } else {
 232                 opts->revs = xmalloc(sizeof(*opts->revs));
 233                 init_revisions(opts->revs, NULL);
 234                 opts->revs->no_walk = 1;
 235                 if (argc < 2)
 236                         usage_with_options(usage_str, options);
 237                 argc = setup_revisions(argc, argv, opts->revs, NULL);
 238         }
 239
 240         if (argc > 1)
 241                 usage_with_options(usage_str, options);
 242 }
 243
 244 struct commit_message {
 245         char *parent_label;
 246         const char *label;
 247         const char *subject;
 248         char *reencoded_message;
 249         const char *message;
 250 };
 251
 252 static int get_message(struct commit *commit, struct commit_message *out)
 253 {
 254         const char *encoding;
 255         const char *abbrev, *subject;
 256         int abbrev_len, subject_len;
 257         char *q;
 258
 259         if (!commit->buffer)
 260                 return -1;
 261         encoding = get_encoding(commit->buffer);
 262         if (!encoding)
 263                 encoding = "UTF-8";
 264         if (!git_commit_encoding)
 265                 git_commit_encoding = "UTF-8";
 266
 267         out->reencoded_message = NULL;
 268         out->message = commit->buffer;
 269         if (strcmp(encoding, git_commit_encoding))
 270                 out->reencoded_message = reencode_string(commit->buffer,
 271                                         git_commit_encoding, encoding);
 272         if (out->reencoded_message)
 273                 out->message = out->reencoded_message;
 274
 275         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 276         abbrev_len = strlen(abbrev);
 277
 278         subject_len = find_commit_subject(out->message, &subject);
 279
 280         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 281                               strlen("... ") + subject_len + 1);
 282         q = out->parent_label;
 283         q = mempcpy(q, "parent of ", strlen("parent of "));
 284         out->label = q;
 285         q = mempcpy(q, abbrev, abbrev_len);
 286         q = mempcpy(q, "... ", strlen("... "));
 287         out->subject = q;
 288         q = mempcpy(q, subject, subject_len);
 289         *q = '\0';
 290         return 0;
 291 }
 292
 293 static void free_message(struct commit_message *msg)
 294 {
 295         free(msg->parent_label);
 296         free(msg->reencoded_message);
 297 }
 298
 299 static char *get_encoding(const char *message)
 300 {
 301         const char *p = message, *eol;
 302
 303         while (*p && *p != '\n') {
 304                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 305                         ; /* do nothing */
 306                 if (!prefixcmp(p, "encoding ")) {
 307                         char *result = xmalloc(eol - 8 - p);
 308                         strlcpy(result, p + 9, eol - 8 - p);
 309                         return result;
 310                 }
 311                 p = eol;
 312                 if (*p == '\n')
 313                         p++;
 314         }
 315         return NULL;
 316 }
 317
 318 static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
 319 {
 320         const char *filename;
 321         int fd;
 322         struct strbuf buf = STRBUF_INIT;
 323
 324         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 325
 326         filename = git_path("%s", pseudoref);
 327         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 328         if (fd < 0)
 329                 die_errno(_("Could not open '%s' for writing"), filename);
 330         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 331                 die_errno(_("Could not write to '%s'"), filename);
 332         strbuf_release(&buf);
 333 }
 334
 335 static void print_advice(int show_hint)
 336 {
 337         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 338
 339         if (msg) {
 340                 fprintf(stderr, "%s\n", msg);
 341                 /*
 342                  * A conflict has occured but the porcelain
 343                  * (typically rebase --interactive) wants to take care
 344                  * of the commit itself so remove CHERRY_PICK_HEAD
 345                  */
 346                 unlink(git_path("CHERRY_PICK_HEAD"));
 347                 return;
 348         }
 349
 350         if (show_hint) {
 351                 advise("after resolving the conflicts, mark the corrected paths");
 352                 advise("with 'git add <paths>' or 'git rm <paths>'");
 353                 advise("and commit the result with 'git commit'");
 354         }
 355 }
 356
 357 static void write_message(struct strbuf *msgbuf, const char *filename)
 358 {
 359         static struct lock_file msg_file;
 360
 361         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 362                                                LOCK_DIE_ON_ERROR);
 363         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 364                 die_errno(_("Could not write to %s"), filename);
 365         strbuf_release(msgbuf);
 366         if (commit_lock_file(&msg_file) < 0)
 367                 die(_("Error wrapping up %s"), filename);
 368 }
 369
 370 static struct tree *empty_tree(void)
 371 {
 372         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 373 }
 374
 375 static int error_dirty_index(struct replay_opts *opts)
 376 {
 377         if (read_cache_unmerged())
 378                 return error_resolve_conflict(action_name(opts));
 379
 380         /* Different translation strings for cherry-pick and revert */
 381         if (opts->action == REPLAY_PICK)
 382                 error(_("Your local changes would be overwritten by cherry-pick."));
 383         else
 384                 error(_("Your local changes would be overwritten by revert."));
 385
 386         if (advice_commit_before_merge)
 387                 advise(_("Commit your changes or stash them to proceed."));
 388         return -1;
 389 }
 390
 391 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 392 {
 393         struct ref_lock *ref_lock;
 394
 395         read_cache();
 396         if (checkout_fast_forward(from, to))
 397                 exit(1); /* the callee should have complained already */
 398         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 399         return write_ref_sha1(ref_lock, to, "cherry-pick");
 400 }
 401
 402 static int do_recursive_merge(struct commit *base, struct commit *next,
 403                               const char *base_label, const char *next_label,
 404                               unsigned char *head, struct strbuf *msgbuf,
 405                               struct replay_opts *opts)
 406 {
 407         struct merge_options o;
 408         struct tree *result, *next_tree, *base_tree, *head_tree;
 409         int clean, index_fd;
 410         const char **xopt;
 411         static struct lock_file index_lock;
 412
 413         index_fd = hold_locked_index(&index_lock, 1);
 414
 415         read_cache();
 416
 417         init_merge_options(&o);
 418         o.ancestor = base ? base_label : "(empty tree)";
 419         o.branch1 = "HEAD";
 420         o.branch2 = next ? next_label : "(empty tree)";
 421
 422         head_tree = parse_tree_indirect(head);
 423         next_tree = next ? next->tree : empty_tree();
 424         base_tree = base ? base->tree : empty_tree();
 425
 426         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 427                 parse_merge_opt(&o, *xopt);
 428
 429         clean = merge_trees(&o,
 430                             head_tree,
 431                             next_tree, base_tree, &result);
 432
 433         if (active_cache_changed &&
 434             (write_cache(index_fd, active_cache, active_nr) ||
 435              commit_locked_index(&index_lock)))
 436                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 437                 die(_("%s: Unable to write new index file"), action_name(opts));
 438         rollback_lock_file(&index_lock);
 439
 440         if (!clean) {
 441                 int i;
 442                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 443                 for (i = 0; i < active_nr;) {
 444                         struct cache_entry *ce = active_cache[i++];
 445                         if (ce_stage(ce)) {
 446                                 strbuf_addch(msgbuf, '\t');
 447                                 strbuf_addstr(msgbuf, ce->name);
 448                                 strbuf_addch(msgbuf, '\n');
 449                                 while (i < active_nr && !strcmp(ce->name,
 450                                                 active_cache[i]->name))
 451                                         i++;
 452                         }
 453                 }
 454         }
 455
 456         return !clean;
 457 }
 458
 459 /*
 460  * If we are cherry-pick, and if the merge did not result in
 461  * hand-editing, we will hit this commit and inherit the original
 462  * author date and name.
 463  * If we are revert, or if our cherry-pick results in a hand merge,
 464  * we had better say that the current user is responsible for that.
 465  */
 466 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 467 {
 468         /* 6 is max possible length of our args array including NULL */
 469         const char *args[6];
 470         int i = 0;
 471
 472         args[i++] = "commit";
 473         args[i++] = "-n";
 474         if (opts->signoff)
 475                 args[i++] = "-s";
 476         if (!opts->edit) {
 477                 args[i++] = "-F";
 478                 args[i++] = defmsg;
 479         }
 480         args[i] = NULL;
 481
 482         return run_command_v_opt(args, RUN_GIT_CMD);
 483 }
 484
 485 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 486 {
 487         unsigned char head[20];
 488         struct commit *base, *next, *parent;
 489         const char *base_label, *next_label;
 490         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 491         char *defmsg = NULL;
 492         struct strbuf msgbuf = STRBUF_INIT;
 493         int res;
 494
 495         if (opts->no_commit) {
 496                 /*
 497                  * We do not intend to commit immediately.  We just want to
 498                  * merge the differences in, so let's compute the tree
 499                  * that represents the "current" state for merge-recursive
 500                  * to work on.
 501                  */
 502                 if (write_cache_as_tree(head, 0, NULL))
 503                         die (_("Your index file is unmerged."));
 504         } else {
 505                 if (get_sha1("HEAD", head))
 506                         return error(_("You do not have a valid HEAD"));
 507                 if (index_differs_from("HEAD", 0))
 508                         return error_dirty_index(opts);
 509         }
 510         discard_cache();
 511
 512         if (!commit->parents) {
 513                 parent = NULL;
 514         }
 515         else if (commit->parents->next) {
 516                 /* Reverting or cherry-picking a merge commit */
 517                 int cnt;
 518                 struct commit_list *p;
 519
 520                 if (!opts->mainline)
 521                         return error(_("Commit %s is a merge but no -m option was given."),
 522                                 sha1_to_hex(commit->object.sha1));
 523
 524                 for (cnt = 1, p = commit->parents;
 525                      cnt != opts->mainline && p;
 526                      cnt++)
 527                         p = p->next;
 528                 if (cnt != opts->mainline || !p)
 529                         return error(_("Commit %s does not have parent %d"),
 530                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 531                 parent = p->item;
 532         } else if (0 < opts->mainline)
 533                 return error(_("Mainline was specified but commit %s is not a merge."),
 534                         sha1_to_hex(commit->object.sha1));
 535         else
 536                 parent = commit->parents->item;
 537
 538         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 539                 return fast_forward_to(commit->object.sha1, head);
 540
 541         if (parent && parse_commit(parent) < 0)
 542                 /* TRANSLATORS: The first %s will be "revert" or
 543                    "cherry-pick", the second %s a SHA1 */
 544                 return error(_("%s: cannot parse parent commit %s"),
 545                         action_name(opts), sha1_to_hex(parent->object.sha1));
 546
 547         if (get_message(commit, &msg) != 0)
 548                 return error(_("Cannot get commit message for %s"),
 549                         sha1_to_hex(commit->object.sha1));
 550
 551         /*
 552          * "commit" is an existing commit.  We would want to apply
 553          * the difference it introduces since its first parent "prev"
 554          * on top of the current HEAD if we are cherry-pick.  Or the
 555          * reverse of it if we are revert.
 556          */
 557
 558         defmsg = git_pathdup("MERGE_MSG");
 559
 560         if (opts->action == REPLAY_REVERT) {
 561                 base = commit;
 562                 base_label = msg.label;
 563                 next = parent;
 564                 next_label = msg.parent_label;
 565                 strbuf_addstr(&msgbuf, "Revert \"");
 566                 strbuf_addstr(&msgbuf, msg.subject);
 567                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 568                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 569
 570                 if (commit->parents && commit->parents->next) {
 571                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 572                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 573                 }
 574                 strbuf_addstr(&msgbuf, ".\n");
 575         } else {
 576                 const char *p;
 577
 578                 base = parent;
 579                 base_label = msg.parent_label;
 580                 next = commit;
 581                 next_label = msg.label;
 582
 583                 /*
 584                  * Append the commit log message to msgbuf; it starts
 585                  * after the tree, parent, author, committer
 586                  * information followed by "\n\n".
 587                  */
 588                 p = strstr(msg.message, "\n\n");
 589                 if (p) {
 590                         p += 2;
 591                         strbuf_addstr(&msgbuf, p);
 592                 }
 593
 594                 if (opts->record_origin) {
 595                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 596                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 597                         strbuf_addstr(&msgbuf, ")\n");
 598                 }
 599         }
 600
 601         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REPLAY_REVERT) {
 602                 res = do_recursive_merge(base, next, base_label, next_label,
 603                                          head, &msgbuf, opts);
 604                 write_message(&msgbuf, defmsg);
 605         } else {
 606                 struct commit_list *common = NULL;
 607                 struct commit_list *remotes = NULL;
 608
 609                 write_message(&msgbuf, defmsg);
 610
 611                 commit_list_insert(base, &common);
 612                 commit_list_insert(next, &remotes);
 613                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 614                                         common, sha1_to_hex(head), remotes);
 615                 free_commit_list(common);
 616                 free_commit_list(remotes);
 617         }
 618
 619         /*
 620          * If the merge was clean or if it failed due to conflict, we write
 621          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 622          * However, if the merge did not even start, then we don't want to
 623          * write it at all.
 624          */
 625         if (opts->action == REPLAY_PICK && !opts->no_commit && (res == 0 || res == 1))
 626                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 627         if (opts->action == REPLAY_REVERT && ((opts->no_commit && res == 0) || res == 1))
 628                 write_cherry_pick_head(commit, "REVERT_HEAD");
 629
 630         if (res) {
 631                 error(opts->action == REPLAY_REVERT
 632                       ? _("could not revert %s... %s")
 633                       : _("could not apply %s... %s"),
 634                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 635                       msg.subject);
 636                 print_advice(res == 1);
 637                 rerere(opts->allow_rerere_auto);
 638         } else {
 639                 if (!opts->no_commit)
 640                         res = run_git_commit(defmsg, opts);
 641         }
 642
 643         free_message(&msg);
 644         free(defmsg);
 645
 646         return res;
 647 }
 648
 649 static void prepare_revs(struct replay_opts *opts)
 650 {
 651         if (opts->action != REPLAY_REVERT)
 652                 opts->revs->reverse ^= 1;
 653
 654         if (prepare_revision_walk(opts->revs))
 655                 die(_("revision walk setup failed"));
 656
 657         if (!opts->revs->commits)
 658                 die(_("empty commit set passed"));
 659 }
 660
 661 static void read_and_refresh_cache(struct replay_opts *opts)
 662 {
 663         static struct lock_file index_lock;
 664         int index_fd = hold_locked_index(&index_lock, 0);
 665         if (read_index_preload(&the_index, NULL) < 0)
 666                 die(_("git %s: failed to read the index"), action_name(opts));
 667         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 668         if (the_index.cache_changed) {
 669                 if (write_index(&the_index, index_fd) ||
 670                     commit_locked_index(&index_lock))
 671                         die(_("git %s: failed to refresh the index"), action_name(opts));
 672         }
 673         rollback_lock_file(&index_lock);
 674 }
 675
 676 /*
 677  * Append a commit to the end of the commit_list.
 678  *
 679  * next starts by pointing to the variable that holds the head of an
 680  * empty commit_list, and is updated to point to the "next" field of
 681  * the last item on the list as new commits are appended.
 682  *
 683  * Usage example:
 684  *
 685  *     struct commit_list *list;
 686  *     struct commit_list **next = &list;
 687  *
 688  *     next = commit_list_append(c1, next);
 689  *     next = commit_list_append(c2, next);
 690  *     assert(commit_list_count(list) == 2);
 691  *     return list;
 692  */
 693 static struct commit_list **commit_list_append(struct commit *commit,
 694                                                struct commit_list **next)
 695 {
 696         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 697         new->item = commit;
 698         *next = new;
 699         new->next = NULL;
 700         return &new->next;
 701 }
 702
 703 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 704                 struct replay_opts *opts)
 705 {
 706         struct commit_list *cur = NULL;
 707         const char *sha1_abbrev = NULL;
 708         const char *action_str = opts->action == REPLAY_REVERT ? "revert" : "pick";
 709         const char *subject;
 710         int subject_len;
 711
 712         for (cur = todo_list; cur; cur = cur->next) {
 713                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 714                 subject_len = find_commit_subject(cur->item->buffer, &subject);
 715                 strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
 716                         subject_len, subject);
 717         }
 718         return 0;
 719 }
 720
 721 static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
 722 {
 723         unsigned char commit_sha1[20];
 724         enum replay_action action;
 725         char *end_of_object_name;
 726         int saved, status, padding;
 727
 728         if (!prefixcmp(bol, "pick")) {
 729                 action = REPLAY_PICK;
 730                 bol += strlen("pick");
 731         } else if (!prefixcmp(bol, "revert")) {
 732                 action = REPLAY_REVERT;
 733                 bol += strlen("revert");
 734         } else
 735                 return NULL;
 736
 737         /* Eat up extra spaces/ tabs before object name */
 738         padding = strspn(bol, " \t");
 739         if (!padding)
 740                 return NULL;
 741         bol += padding;
 742
 743         end_of_object_name = bol + strcspn(bol, " \t\n");
 744         saved = *end_of_object_name;
 745         *end_of_object_name = '\0';
 746         status = get_sha1(bol, commit_sha1);
 747         *end_of_object_name = saved;
 748
 749         /*
 750          * Verify that the action matches up with the one in
 751          * opts; we don't support arbitrary instructions
 752          */
 753         if (action != opts->action) {
 754                 const char *action_str;
 755                 action_str = action == REPLAY_REVERT ? "revert" : "cherry-pick";
 756                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 757                 return NULL;
 758         }
 759
 760         if (status < 0)
 761                 return NULL;
 762
 763         return lookup_commit_reference(commit_sha1);
 764 }
 765
 766 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 767                         struct replay_opts *opts)
 768 {
 769         struct commit_list **next = todo_list;
 770         struct commit *commit;
 771         char *p = buf;
 772         int i;
 773
 774         for (i = 1; *p; i++) {
 775                 char *eol = strchrnul(p, '\n');
 776                 commit = parse_insn_line(p, eol, opts);
 777                 if (!commit)
 778                         return error(_("Could not parse line %d."), i);
 779                 next = commit_list_append(commit, next);
 780                 p = *eol ? eol + 1 : eol;
 781         }
 782         if (!*todo_list)
 783                 return error(_("No commits parsed."));
 784         return 0;
 785 }
 786
 787 static void read_populate_todo(struct commit_list **todo_list,
 788                         struct replay_opts *opts)
 789 {
 790         const char *todo_file = git_path(SEQ_TODO_FILE);
 791         struct strbuf buf = STRBUF_INIT;
 792         int fd, res;
 793
 794         fd = open(todo_file, O_RDONLY);
 795         if (fd < 0)
 796                 die_errno(_("Could not open %s"), todo_file);
 797         if (strbuf_read(&buf, fd, 0) < 0) {
 798                 close(fd);
 799                 strbuf_release(&buf);
 800                 die(_("Could not read %s."), todo_file);
 801         }
 802         close(fd);
 803
 804         res = parse_insn_buffer(buf.buf, todo_list, opts);
 805         strbuf_release(&buf);
 806         if (res)
 807                 die(_("Unusable instruction sheet: %s"), todo_file);
 808 }
 809
 810 static int populate_opts_cb(const char *key, const char *value, void *data)
 811 {
 812         struct replay_opts *opts = data;
 813         int error_flag = 1;
 814
 815         if (!value)
 816                 error_flag = 0;
 817         else if (!strcmp(key, "options.no-commit"))
 818                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 819         else if (!strcmp(key, "options.edit"))
 820                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 821         else if (!strcmp(key, "options.signoff"))
 822                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 823         else if (!strcmp(key, "options.record-origin"))
 824                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 825         else if (!strcmp(key, "options.allow-ff"))
 826                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 827         else if (!strcmp(key, "options.mainline"))
 828                 opts->mainline = git_config_int(key, value);
 829         else if (!strcmp(key, "options.strategy"))
 830                 git_config_string(&opts->strategy, key, value);
 831         else if (!strcmp(key, "options.strategy-option")) {
 832                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 833                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 834         } else
 835                 return error(_("Invalid key: %s"), key);
 836
 837         if (!error_flag)
 838                 return error(_("Invalid value for %s: %s"), key, value);
 839
 840         return 0;
 841 }
 842
 843 static void read_populate_opts(struct replay_opts **opts_ptr)
 844 {
 845         const char *opts_file = git_path(SEQ_OPTS_FILE);
 846
 847         if (!file_exists(opts_file))
 848                 return;
 849         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 850                 die(_("Malformed options sheet: %s"), opts_file);
 851 }
 852
 853 static void walk_revs_populate_todo(struct commit_list **todo_list,
 854                                 struct replay_opts *opts)
 855 {
 856         struct commit *commit;
 857         struct commit_list **next;
 858
 859         prepare_revs(opts);
 860
 861         next = todo_list;
 862         while ((commit = get_revision(opts->revs)))
 863                 next = commit_list_append(commit, next);
 864 }
 865
 866 static int create_seq_dir(void)
 867 {
 868         const char *seq_dir = git_path(SEQ_DIR);
 869
 870         if (file_exists(seq_dir)) {
 871                 error(_("a cherry-pick or revert is already in progress"));
 872                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 873                 return -1;
 874         }
 875         else if (mkdir(seq_dir, 0777) < 0)
 876                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 877         return 0;
 878 }
 879
 880 static void save_head(const char *head)
 881 {
 882         const char *head_file = git_path(SEQ_HEAD_FILE);
 883         static struct lock_file head_lock;
 884         struct strbuf buf = STRBUF_INIT;
 885         int fd;
 886
 887         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 888         strbuf_addf(&buf, "%s\n", head);
 889         if (write_in_full(fd, buf.buf, buf.len) < 0)
 890                 die_errno(_("Could not write to %s"), head_file);
 891         if (commit_lock_file(&head_lock) < 0)
 892                 die(_("Error wrapping up %s."), head_file);
 893 }
 894
 895 static int reset_for_rollback(const unsigned char *sha1)
 896 {
 897         const char *argv[4];    /* reset --merge <arg> + NULL */
 898         argv[0] = "reset";
 899         argv[1] = "--merge";
 900         argv[2] = sha1_to_hex(sha1);
 901         argv[3] = NULL;
 902         return run_command_v_opt(argv, RUN_GIT_CMD);
 903 }
 904
 905 static int rollback_single_pick(void)
 906 {
 907         unsigned char head_sha1[20];
 908
 909         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 910             !file_exists(git_path("REVERT_HEAD")))
 911                 return error(_("no cherry-pick or revert in progress"));
 912         if (read_ref_full("HEAD", head_sha1, 0, NULL))
 913                 return error(_("cannot resolve HEAD"));
 914         if (is_null_sha1(head_sha1))
 915                 return error(_("cannot abort from a branch yet to be born"));
 916         return reset_for_rollback(head_sha1);
 917 }
 918
 919 static int sequencer_rollback(struct replay_opts *opts)
 920 {
 921         const char *filename;
 922         FILE *f;
 923         unsigned char sha1[20];
 924         struct strbuf buf = STRBUF_INIT;
 925
 926         filename = git_path(SEQ_HEAD_FILE);
 927         f = fopen(filename, "r");
 928         if (!f && errno == ENOENT) {
 929                 /*
 930                  * There is no multiple-cherry-pick in progress.
 931                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 932                  * a single-cherry-pick in progress, abort that.
 933                  */
 934                 return rollback_single_pick();
 935         }
 936         if (!f)
 937                 return error(_("cannot open %s: %s"), filename,
 938                                                 strerror(errno));
 939         if (strbuf_getline(&buf, f, '\n')) {
 940                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 941                         strerror(errno) : _("unexpected end of file"));
 942                 fclose(f);
 943                 goto fail;
 944         }
 945         fclose(f);
 946         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 947                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 948                         filename);
 949                 goto fail;
 950         }
 951         if (reset_for_rollback(sha1))
 952                 goto fail;
 953         remove_sequencer_state();
 954         strbuf_release(&buf);
 955         return 0;
 956 fail:
 957         strbuf_release(&buf);
 958         return -1;
 959 }
 960
 961 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 962 {
 963         const char *todo_file = git_path(SEQ_TODO_FILE);
 964         static struct lock_file todo_lock;
 965         struct strbuf buf = STRBUF_INIT;
 966         int fd;
 967
 968         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 969         if (format_todo(&buf, todo_list, opts) < 0)
 970                 die(_("Could not format %s."), todo_file);
 971         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 972                 strbuf_release(&buf);
 973                 die_errno(_("Could not write to %s"), todo_file);
 974         }
 975         if (commit_lock_file(&todo_lock) < 0) {
 976                 strbuf_release(&buf);
 977                 die(_("Error wrapping up %s."), todo_file);
 978         }
 979         strbuf_release(&buf);
 980 }
 981
 982 static void save_opts(struct replay_opts *opts)
 983 {
 984         const char *opts_file = git_path(SEQ_OPTS_FILE);
 985
 986         if (opts->no_commit)
 987                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 988         if (opts->edit)
 989                 git_config_set_in_file(opts_file, "options.edit", "true");
 990         if (opts->signoff)
 991                 git_config_set_in_file(opts_file, "options.signoff", "true");
 992         if (opts->record_origin)
 993                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 994         if (opts->allow_ff)
 995                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 996         if (opts->mainline) {
 997                 struct strbuf buf = STRBUF_INIT;
 998                 strbuf_addf(&buf, "%d", opts->mainline);
 999                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
1000                 strbuf_release(&buf);
1001         }
1002         if (opts->strategy)
1003                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
1004         if (opts->xopts) {
1005                 int i;
1006                 for (i = 0; i < opts->xopts_nr; i++)
1007                         git_config_set_multivar_in_file(opts_file,
1008                                                         "options.strategy-option",
1009                                                         opts->xopts[i], "^$", 0);
1010         }
1011 }
1012
1013 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
1014 {
1015         struct commit_list *cur;
1016         int res;
1017
1018         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1019         if (opts->allow_ff)
1020                 assert(!(opts->signoff || opts->no_commit ||
1021                                 opts->record_origin || opts->edit));
1022         read_and_refresh_cache(opts);
1023
1024         for (cur = todo_list; cur; cur = cur->next) {
1025                 save_todo(cur, opts);
1026                 res = do_pick_commit(cur->item, opts);
1027                 if (res)
1028                         return res;
1029         }
1030
1031         /*
1032          * Sequence of picks finished successfully; cleanup by
1033          * removing the .git/sequencer directory
1034          */
1035         remove_sequencer_state();
1036         return 0;
1037 }
1038
1039 static int continue_single_pick(void)
1040 {
1041         const char *argv[] = { "commit", NULL };
1042
1043         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
1044             !file_exists(git_path("REVERT_HEAD")))
1045                 return error(_("no cherry-pick or revert in progress"));
1046         return run_command_v_opt(argv, RUN_GIT_CMD);
1047 }
1048
1049 static int sequencer_continue(struct replay_opts *opts)
1050 {
1051         struct commit_list *todo_list = NULL;
1052
1053         if (!file_exists(git_path(SEQ_TODO_FILE)))
1054                 return continue_single_pick();
1055         read_populate_opts(&opts);
1056         read_populate_todo(&todo_list, opts);
1057
1058         /* Verify that the conflict has been resolved */
1059         if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
1060             file_exists(git_path("REVERT_HEAD"))) {
1061                 int ret = continue_single_pick();
1062                 if (ret)
1063                         return ret;
1064         }
1065         if (index_differs_from("HEAD", 0))
1066                 return error_dirty_index(opts);
1067         todo_list = todo_list->next;
1068         return pick_commits(todo_list, opts);
1069 }
1070
1071 static int single_pick(struct commit *cmit, struct replay_opts *opts)
1072 {
1073         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1074         return do_pick_commit(cmit, opts);
1075 }
1076
1077 static int pick_revisions(struct replay_opts *opts)
1078 {
1079         struct commit_list *todo_list = NULL;
1080         unsigned char sha1[20];
1081
1082         if (opts->subcommand == REPLAY_NONE)
1083                 assert(opts->revs);
1084
1085         read_and_refresh_cache(opts);
1086
1087         /*
1088          * Decide what to do depending on the arguments; a fresh
1089          * cherry-pick should be handled differently from an existing
1090          * one that is being continued
1091          */
1092         if (opts->subcommand == REPLAY_REMOVE_STATE) {
1093                 remove_sequencer_state();
1094                 return 0;
1095         }
1096         if (opts->subcommand == REPLAY_ROLLBACK)
1097                 return sequencer_rollback(opts);
1098         if (opts->subcommand == REPLAY_CONTINUE)
1099                 return sequencer_continue(opts);
1100
1101         /*
1102          * If we were called as "git cherry-pick <commit>", just
1103          * cherry-pick/revert it, set CHERRY_PICK_HEAD /
1104          * REVERT_HEAD, and don't touch the sequencer state.
1105          * This means it is possible to cherry-pick in the middle
1106          * of a cherry-pick sequence.
1107          */
1108         if (opts->revs->cmdline.nr == 1 &&
1109             opts->revs->cmdline.rev->whence == REV_CMD_REV &&
1110             opts->revs->no_walk &&
1111             !opts->revs->cmdline.rev->flags) {
1112                 struct commit *cmit;
1113                 if (prepare_revision_walk(opts->revs))
1114                         die(_("revision walk setup failed"));
1115                 cmit = get_revision(opts->revs);
1116                 if (!cmit || get_revision(opts->revs))
1117                         die("BUG: expected exactly one commit from walk");
1118                 return single_pick(cmit, opts);
1119         }
1120
1121         /*
1122          * Start a new cherry-pick/ revert sequence; but
1123          * first, make sure that an existing one isn't in
1124          * progress
1125          */
1126
1127         walk_revs_populate_todo(&todo_list, opts);
1128         if (create_seq_dir() < 0)
1129                 return -1;
1130         if (get_sha1("HEAD", sha1)) {
1131                 if (opts->action == REPLAY_REVERT)
1132                         return error(_("Can't revert as initial commit"));
1133                 return error(_("Can't cherry-pick into empty head"));
1134         }
1135         save_head(sha1_to_hex(sha1));
1136         save_opts(opts);
1137         return pick_commits(todo_list, opts);
1138 }
1139
1140 int cmd_revert(int argc, const char **argv, const char *prefix)
1141 {
1142         struct replay_opts opts;
1143         int res;
1144
1145         memset(&opts, 0, sizeof(opts));
1146         if (isatty(0))
1147                 opts.edit = 1;
1148         opts.action = REPLAY_REVERT;
1149         git_config(git_default_config, NULL);
1150         parse_args(argc, argv, &opts);
1151         res = pick_revisions(&opts);
1152         if (res < 0)
1153                 die(_("revert failed"));
1154         return res;
1155 }
1156
1157 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1158 {
1159         struct replay_opts opts;
1160         int res;
1161
1162         memset(&opts, 0, sizeof(opts));
1163         opts.action = REPLAY_PICK;
1164         git_config(git_default_config, NULL);
1165         parse_args(argc, argv, &opts);
1166         res = pick_revisions(&opts);
1167         if (res < 0)
1168                 die(_("cherry-pick failed"));
1169         return res;
1170 }