builtin/revert.c

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