git.oblomov.eu Git - git/blob - 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(int show_hint)
 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         if (show_hint) {
 321                 advise("after resolving the conflicts, mark the corrected paths");
 322                 advise("with 'git add <paths>' or 'git rm <paths>'");
 323                 advise("and commit the result with 'git commit'");
 324         }
 325 }
 326
 327 static void write_message(struct strbuf *msgbuf, const char *filename)
 328 {
 329         static struct lock_file msg_file;
 330
 331         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 332                                                LOCK_DIE_ON_ERROR);
 333         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 334                 die_errno(_("Could not write to %s."), filename);
 335         strbuf_release(msgbuf);
 336         if (commit_lock_file(&msg_file) < 0)
 337                 die(_("Error wrapping up %s"), filename);
 338 }
 339
 340 static struct tree *empty_tree(void)
 341 {
 342         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 343 }
 344
 345 static int error_dirty_index(struct replay_opts *opts)
 346 {
 347         if (read_cache_unmerged())
 348                 return error_resolve_conflict(action_name(opts));
 349
 350         /* Different translation strings for cherry-pick and revert */
 351         if (opts->action == CHERRY_PICK)
 352                 error(_("Your local changes would be overwritten by cherry-pick."));
 353         else
 354                 error(_("Your local changes would be overwritten by revert."));
 355
 356         if (advice_commit_before_merge)
 357                 advise(_("Commit your changes or stash them to proceed."));
 358         return -1;
 359 }
 360
 361 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 362 {
 363         struct ref_lock *ref_lock;
 364
 365         read_cache();
 366         if (checkout_fast_forward(from, to))
 367                 exit(1); /* the callee should have complained already */
 368         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 369         return write_ref_sha1(ref_lock, to, "cherry-pick");
 370 }
 371
 372 static int do_recursive_merge(struct commit *base, struct commit *next,
 373                               const char *base_label, const char *next_label,
 374                               unsigned char *head, struct strbuf *msgbuf,
 375                               struct replay_opts *opts)
 376 {
 377         struct merge_options o;
 378         struct tree *result, *next_tree, *base_tree, *head_tree;
 379         int clean, index_fd;
 380         const char **xopt;
 381         static struct lock_file index_lock;
 382
 383         index_fd = hold_locked_index(&index_lock, 1);
 384
 385         read_cache();
 386
 387         init_merge_options(&o);
 388         o.ancestor = base ? base_label : "(empty tree)";
 389         o.branch1 = "HEAD";
 390         o.branch2 = next ? next_label : "(empty tree)";
 391
 392         head_tree = parse_tree_indirect(head);
 393         next_tree = next ? next->tree : empty_tree();
 394         base_tree = base ? base->tree : empty_tree();
 395
 396         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 397                 parse_merge_opt(&o, *xopt);
 398
 399         clean = merge_trees(&o,
 400                             head_tree,
 401                             next_tree, base_tree, &result);
 402
 403         if (active_cache_changed &&
 404             (write_cache(index_fd, active_cache, active_nr) ||
 405              commit_locked_index(&index_lock)))
 406                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 407                 die(_("%s: Unable to write new index file"), action_name(opts));
 408         rollback_lock_file(&index_lock);
 409
 410         if (!clean) {
 411                 int i;
 412                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 413                 for (i = 0; i < active_nr;) {
 414                         struct cache_entry *ce = active_cache[i++];
 415                         if (ce_stage(ce)) {
 416                                 strbuf_addch(msgbuf, '\t');
 417                                 strbuf_addstr(msgbuf, ce->name);
 418                                 strbuf_addch(msgbuf, '\n');
 419                                 while (i < active_nr && !strcmp(ce->name,
 420                                                 active_cache[i]->name))
 421                                         i++;
 422                         }
 423                 }
 424         }
 425
 426         return !clean;
 427 }
 428
 429 /*
 430  * If we are cherry-pick, and if the merge did not result in
 431  * hand-editing, we will hit this commit and inherit the original
 432  * author date and name.
 433  * If we are revert, or if our cherry-pick results in a hand merge,
 434  * we had better say that the current user is responsible for that.
 435  */
 436 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 437 {
 438         /* 6 is max possible length of our args array including NULL */
 439         const char *args[6];
 440         int i = 0;
 441
 442         args[i++] = "commit";
 443         args[i++] = "-n";
 444         if (opts->signoff)
 445                 args[i++] = "-s";
 446         if (!opts->edit) {
 447                 args[i++] = "-F";
 448                 args[i++] = defmsg;
 449         }
 450         args[i] = NULL;
 451
 452         return run_command_v_opt(args, RUN_GIT_CMD);
 453 }
 454
 455 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 456 {
 457         unsigned char head[20];
 458         struct commit *base, *next, *parent;
 459         const char *base_label, *next_label;
 460         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 461         char *defmsg = NULL;
 462         struct strbuf msgbuf = STRBUF_INIT;
 463         int res;
 464
 465         if (opts->no_commit) {
 466                 /*
 467                  * We do not intend to commit immediately.  We just want to
 468                  * merge the differences in, so let's compute the tree
 469                  * that represents the "current" state for merge-recursive
 470                  * to work on.
 471                  */
 472                 if (write_cache_as_tree(head, 0, NULL))
 473                         die (_("Your index file is unmerged."));
 474         } else {
 475                 if (get_sha1("HEAD", head))
 476                         return error(_("You do not have a valid HEAD"));
 477                 if (index_differs_from("HEAD", 0))
 478                         return error_dirty_index(opts);
 479         }
 480         discard_cache();
 481
 482         if (!commit->parents) {
 483                 parent = NULL;
 484         }
 485         else if (commit->parents->next) {
 486                 /* Reverting or cherry-picking a merge commit */
 487                 int cnt;
 488                 struct commit_list *p;
 489
 490                 if (!opts->mainline)
 491                         return error(_("Commit %s is a merge but no -m option was given."),
 492                                 sha1_to_hex(commit->object.sha1));
 493
 494                 for (cnt = 1, p = commit->parents;
 495                      cnt != opts->mainline && p;
 496                      cnt++)
 497                         p = p->next;
 498                 if (cnt != opts->mainline || !p)
 499                         return error(_("Commit %s does not have parent %d"),
 500                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 501                 parent = p->item;
 502         } else if (0 < opts->mainline)
 503                 return error(_("Mainline was specified but commit %s is not a merge."),
 504                         sha1_to_hex(commit->object.sha1));
 505         else
 506                 parent = commit->parents->item;
 507
 508         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 509                 return fast_forward_to(commit->object.sha1, head);
 510
 511         if (parent && parse_commit(parent) < 0)
 512                 /* TRANSLATORS: The first %s will be "revert" or
 513                    "cherry-pick", the second %s a SHA1 */
 514                 return error(_("%s: cannot parse parent commit %s"),
 515                         action_name(opts), sha1_to_hex(parent->object.sha1));
 516
 517         if (get_message(commit, &msg) != 0)
 518                 return error(_("Cannot get commit message for %s"),
 519                         sha1_to_hex(commit->object.sha1));
 520
 521         /*
 522          * "commit" is an existing commit.  We would want to apply
 523          * the difference it introduces since its first parent "prev"
 524          * on top of the current HEAD if we are cherry-pick.  Or the
 525          * reverse of it if we are revert.
 526          */
 527
 528         defmsg = git_pathdup("MERGE_MSG");
 529
 530         if (opts->action == REVERT) {
 531                 base = commit;
 532                 base_label = msg.label;
 533                 next = parent;
 534                 next_label = msg.parent_label;
 535                 strbuf_addstr(&msgbuf, "Revert \"");
 536                 strbuf_addstr(&msgbuf, msg.subject);
 537                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 538                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 539
 540                 if (commit->parents && commit->parents->next) {
 541                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 542                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 543                 }
 544                 strbuf_addstr(&msgbuf, ".\n");
 545         } else {
 546                 const char *p;
 547
 548                 base = parent;
 549                 base_label = msg.parent_label;
 550                 next = commit;
 551                 next_label = msg.label;
 552
 553                 /*
 554                  * Append the commit log message to msgbuf; it starts
 555                  * after the tree, parent, author, committer
 556                  * information followed by "\n\n".
 557                  */
 558                 p = strstr(msg.message, "\n\n");
 559                 if (p) {
 560                         p += 2;
 561                         strbuf_addstr(&msgbuf, p);
 562                 }
 563
 564                 if (opts->record_origin) {
 565                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 566                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 567                         strbuf_addstr(&msgbuf, ")\n");
 568                 }
 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         /*
 590          * If the merge was clean or if it failed due to conflict, we write
 591          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 592          * However, if the merge did not even start, then we don't want to
 593          * write it at all.
 594          */
 595         if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
 596                 write_cherry_pick_head(commit);
 597
 598         if (res) {
 599                 error(opts->action == REVERT
 600                       ? _("could not revert %s... %s")
 601                       : _("could not apply %s... %s"),
 602                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 603                       msg.subject);
 604                 print_advice(res == 1);
 605                 rerere(opts->allow_rerere_auto);
 606         } else {
 607                 if (!opts->no_commit)
 608                         res = run_git_commit(defmsg, opts);
 609         }
 610
 611         free_message(&msg);
 612         free(defmsg);
 613
 614         return res;
 615 }
 616
 617 static void prepare_revs(struct rev_info *revs, struct replay_opts *opts)
 618 {
 619         int argc;
 620
 621         init_revisions(revs, NULL);
 622         revs->no_walk = 1;
 623         if (opts->action != REVERT)
 624                 revs->reverse = 1;
 625
 626         argc = setup_revisions(opts->commit_argc, opts->commit_argv, revs, NULL);
 627         if (argc > 1)
 628                 usage(*revert_or_cherry_pick_usage(opts));
 629
 630         if (prepare_revision_walk(revs))
 631                 die(_("revision walk setup failed"));
 632
 633         if (!revs->commits)
 634                 die(_("empty commit set passed"));
 635 }
 636
 637 static void read_and_refresh_cache(struct replay_opts *opts)
 638 {
 639         static struct lock_file index_lock;
 640         int index_fd = hold_locked_index(&index_lock, 0);
 641         if (read_index_preload(&the_index, NULL) < 0)
 642                 die(_("git %s: failed to read the index"), action_name(opts));
 643         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 644         if (the_index.cache_changed) {
 645                 if (write_index(&the_index, index_fd) ||
 646                     commit_locked_index(&index_lock))
 647                         die(_("git %s: failed to refresh the index"), action_name(opts));
 648         }
 649         rollback_lock_file(&index_lock);
 650 }
 651
 652 /*
 653  * Append a commit to the end of the commit_list.
 654  *
 655  * next starts by pointing to the variable that holds the head of an
 656  * empty commit_list, and is updated to point to the "next" field of
 657  * the last item on the list as new commits are appended.
 658  *
 659  * Usage example:
 660  *
 661  *     struct commit_list *list;
 662  *     struct commit_list **next = &list;
 663  *
 664  *     next = commit_list_append(c1, next);
 665  *     next = commit_list_append(c2, next);
 666  *     assert(commit_list_count(list) == 2);
 667  *     return list;
 668  */
 669 static struct commit_list **commit_list_append(struct commit *commit,
 670                                                struct commit_list **next)
 671 {
 672         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 673         new->item = commit;
 674         *next = new;
 675         new->next = NULL;
 676         return &new->next;
 677 }
 678
 679 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 680                 struct replay_opts *opts)
 681 {
 682         struct commit_list *cur = NULL;
 683         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 684         const char *sha1_abbrev = NULL;
 685         const char *action_str = opts->action == REVERT ? "revert" : "pick";
 686
 687         for (cur = todo_list; cur; cur = cur->next) {
 688                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 689                 if (get_message(cur->item, &msg))
 690                         return error(_("Cannot get commit message for %s"), sha1_abbrev);
 691                 strbuf_addf(buf, "%s %s %s\n", action_str, sha1_abbrev, msg.subject);
 692         }
 693         return 0;
 694 }
 695
 696 static struct commit *parse_insn_line(char *start, struct replay_opts *opts)
 697 {
 698         unsigned char commit_sha1[20];
 699         char sha1_abbrev[40];
 700         enum replay_action action;
 701         int insn_len = 0;
 702         char *p, *q;
 703
 704         if (!prefixcmp(start, "pick ")) {
 705                 action = CHERRY_PICK;
 706                 insn_len = strlen("pick");
 707                 p = start + insn_len + 1;
 708         } else if (!prefixcmp(start, "revert ")) {
 709                 action = REVERT;
 710                 insn_len = strlen("revert");
 711                 p = start + insn_len + 1;
 712         } else
 713                 return NULL;
 714
 715         q = strchr(p, ' ');
 716         if (!q)
 717                 return NULL;
 718         q++;
 719
 720         strlcpy(sha1_abbrev, p, q - p);
 721
 722         /*
 723          * Verify that the action matches up with the one in
 724          * opts; we don't support arbitrary instructions
 725          */
 726         if (action != opts->action) {
 727                 const char *action_str;
 728                 action_str = action == REVERT ? "revert" : "cherry-pick";
 729                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 730                 return NULL;
 731         }
 732
 733         if (get_sha1(sha1_abbrev, commit_sha1) < 0)
 734                 return NULL;
 735
 736         return lookup_commit_reference(commit_sha1);
 737 }
 738
 739 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 740                         struct replay_opts *opts)
 741 {
 742         struct commit_list **next = todo_list;
 743         struct commit *commit;
 744         char *p = buf;
 745         int i;
 746
 747         for (i = 1; *p; i++) {
 748                 commit = parse_insn_line(p, opts);
 749                 if (!commit)
 750                         return error(_("Could not parse line %d."), i);
 751                 next = commit_list_append(commit, next);
 752                 p = strchrnul(p, '\n');
 753                 if (*p)
 754                         p++;
 755         }
 756         if (!*todo_list)
 757                 return error(_("No commits parsed."));
 758         return 0;
 759 }
 760
 761 static void read_populate_todo(struct commit_list **todo_list,
 762                         struct replay_opts *opts)
 763 {
 764         const char *todo_file = git_path(SEQ_TODO_FILE);
 765         struct strbuf buf = STRBUF_INIT;
 766         int fd, res;
 767
 768         fd = open(todo_file, O_RDONLY);
 769         if (fd < 0)
 770                 die_errno(_("Could not open %s."), todo_file);
 771         if (strbuf_read(&buf, fd, 0) < 0) {
 772                 close(fd);
 773                 strbuf_release(&buf);
 774                 die(_("Could not read %s."), todo_file);
 775         }
 776         close(fd);
 777
 778         res = parse_insn_buffer(buf.buf, todo_list, opts);
 779         strbuf_release(&buf);
 780         if (res)
 781                 die(_("Unusable instruction sheet: %s"), todo_file);
 782 }
 783
 784 static int populate_opts_cb(const char *key, const char *value, void *data)
 785 {
 786         struct replay_opts *opts = data;
 787         int error_flag = 1;
 788
 789         if (!value)
 790                 error_flag = 0;
 791         else if (!strcmp(key, "options.no-commit"))
 792                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 793         else if (!strcmp(key, "options.edit"))
 794                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 795         else if (!strcmp(key, "options.signoff"))
 796                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 797         else if (!strcmp(key, "options.record-origin"))
 798                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 799         else if (!strcmp(key, "options.allow-ff"))
 800                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 801         else if (!strcmp(key, "options.mainline"))
 802                 opts->mainline = git_config_int(key, value);
 803         else if (!strcmp(key, "options.strategy"))
 804                 git_config_string(&opts->strategy, key, value);
 805         else if (!strcmp(key, "options.strategy-option")) {
 806                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 807                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 808         } else
 809                 return error(_("Invalid key: %s"), key);
 810
 811         if (!error_flag)
 812                 return error(_("Invalid value for %s: %s"), key, value);
 813
 814         return 0;
 815 }
 816
 817 static void read_populate_opts(struct replay_opts **opts_ptr)
 818 {
 819         const char *opts_file = git_path(SEQ_OPTS_FILE);
 820
 821         if (!file_exists(opts_file))
 822                 return;
 823         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 824                 die(_("Malformed options sheet: %s"), opts_file);
 825 }
 826
 827 static void walk_revs_populate_todo(struct commit_list **todo_list,
 828                                 struct replay_opts *opts)
 829 {
 830         struct rev_info revs;
 831         struct commit *commit;
 832         struct commit_list **next;
 833
 834         prepare_revs(&revs, opts);
 835
 836         next = todo_list;
 837         while ((commit = get_revision(&revs)))
 838                 next = commit_list_append(commit, next);
 839 }
 840
 841 static int create_seq_dir(void)
 842 {
 843         const char *seq_dir = git_path(SEQ_DIR);
 844
 845         if (file_exists(seq_dir))
 846                 return error(_("%s already exists."), seq_dir);
 847         else if (mkdir(seq_dir, 0777) < 0)
 848                 die_errno(_("Could not create sequencer directory '%s'."), seq_dir);
 849         return 0;
 850 }
 851
 852 static void save_head(const char *head)
 853 {
 854         const char *head_file = git_path(SEQ_HEAD_FILE);
 855         static struct lock_file head_lock;
 856         struct strbuf buf = STRBUF_INIT;
 857         int fd;
 858
 859         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 860         strbuf_addf(&buf, "%s\n", head);
 861         if (write_in_full(fd, buf.buf, buf.len) < 0)
 862                 die_errno(_("Could not write to %s."), head_file);
 863         if (commit_lock_file(&head_lock) < 0)
 864                 die(_("Error wrapping up %s."), head_file);
 865 }
 866
 867 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 868 {
 869         const char *todo_file = git_path(SEQ_TODO_FILE);
 870         static struct lock_file todo_lock;
 871         struct strbuf buf = STRBUF_INIT;
 872         int fd;
 873
 874         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 875         if (format_todo(&buf, todo_list, opts) < 0)
 876                 die(_("Could not format %s."), todo_file);
 877         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 878                 strbuf_release(&buf);
 879                 die_errno(_("Could not write to %s."), todo_file);
 880         }
 881         if (commit_lock_file(&todo_lock) < 0) {
 882                 strbuf_release(&buf);
 883                 die(_("Error wrapping up %s."), todo_file);
 884         }
 885         strbuf_release(&buf);
 886 }
 887
 888 static void save_opts(struct replay_opts *opts)
 889 {
 890         const char *opts_file = git_path(SEQ_OPTS_FILE);
 891
 892         if (opts->no_commit)
 893                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 894         if (opts->edit)
 895                 git_config_set_in_file(opts_file, "options.edit", "true");
 896         if (opts->signoff)
 897                 git_config_set_in_file(opts_file, "options.signoff", "true");
 898         if (opts->record_origin)
 899                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 900         if (opts->allow_ff)
 901                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 902         if (opts->mainline) {
 903                 struct strbuf buf = STRBUF_INIT;
 904                 strbuf_addf(&buf, "%d", opts->mainline);
 905                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 906                 strbuf_release(&buf);
 907         }
 908         if (opts->strategy)
 909                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 910         if (opts->xopts) {
 911                 int i;
 912                 for (i = 0; i < opts->xopts_nr; i++)
 913                         git_config_set_multivar_in_file(opts_file,
 914                                                         "options.strategy-option",
 915                                                         opts->xopts[i], "^$", 0);
 916         }
 917 }
 918
 919 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
 920 {
 921         struct commit_list *cur;
 922         int res;
 923
 924         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 925         if (opts->allow_ff)
 926                 assert(!(opts->signoff || opts->no_commit ||
 927                                 opts->record_origin || opts->edit));
 928         read_and_refresh_cache(opts);
 929
 930         for (cur = todo_list; cur; cur = cur->next) {
 931                 save_todo(cur, opts);
 932                 res = do_pick_commit(cur->item, opts);
 933                 if (res) {
 934                         if (!cur->next)
 935                                 /*
 936                                  * An error was encountered while
 937                                  * picking the last commit; the
 938                                  * sequencer state is useless now --
 939                                  * the user simply needs to resolve
 940                                  * the conflict and commit
 941                                  */
 942                                 remove_sequencer_state(0);
 943                         return res;
 944                 }
 945         }
 946
 947         /*
 948          * Sequence of picks finished successfully; cleanup by
 949          * removing the .git/sequencer directory
 950          */
 951         remove_sequencer_state(1);
 952         return 0;
 953 }
 954
 955 static int pick_revisions(struct replay_opts *opts)
 956 {
 957         struct commit_list *todo_list = NULL;
 958         unsigned char sha1[20];
 959
 960         read_and_refresh_cache(opts);
 961
 962         /*
 963          * Decide what to do depending on the arguments; a fresh
 964          * cherry-pick should be handled differently from an existing
 965          * one that is being continued
 966          */
 967         if (opts->subcommand == REPLAY_RESET) {
 968                 remove_sequencer_state(1);
 969                 return 0;
 970         } else if (opts->subcommand == REPLAY_CONTINUE) {
 971                 if (!file_exists(git_path(SEQ_TODO_FILE)))
 972                         goto error;
 973                 read_populate_opts(&opts);
 974                 read_populate_todo(&todo_list, opts);
 975
 976                 /* Verify that the conflict has been resolved */
 977                 if (!index_differs_from("HEAD", 0))
 978                         todo_list = todo_list->next;
 979         } else {
 980                 /*
 981                  * Start a new cherry-pick/ revert sequence; but
 982                  * first, make sure that an existing one isn't in
 983                  * progress
 984                  */
 985
 986                 walk_revs_populate_todo(&todo_list, opts);
 987                 if (create_seq_dir() < 0) {
 988                         error(_("A cherry-pick or revert is in progress."));
 989                         advise(_("Use --continue to continue the operation"));
 990                         advise(_("or --reset to forget about it"));
 991                         return -1;
 992                 }
 993                 if (get_sha1("HEAD", sha1)) {
 994                         if (opts->action == REVERT)
 995                                 return error(_("Can't revert as initial commit"));
 996                         return error(_("Can't cherry-pick into empty head"));
 997                 }
 998                 save_head(sha1_to_hex(sha1));
 999                 save_opts(opts);
1000         }
1001         return pick_commits(todo_list, opts);
1002 error:
1003         return error(_("No %s in progress"), action_name(opts));
1004 }
1005
1006 int cmd_revert(int argc, const char **argv, const char *prefix)
1007 {
1008         struct replay_opts opts;
1009         int res;
1010
1011         memset(&opts, 0, sizeof(opts));
1012         if (isatty(0))
1013                 opts.edit = 1;
1014         opts.action = REVERT;
1015         git_config(git_default_config, NULL);
1016         parse_args(argc, argv, &opts);
1017         res = pick_revisions(&opts);
1018         if (res < 0)
1019                 die(_("revert failed"));
1020         return res;
1021 }
1022
1023 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1024 {
1025         struct replay_opts opts;
1026         int res;
1027
1028         memset(&opts, 0, sizeof(opts));
1029         opts.action = CHERRY_PICK;
1030         git_config(git_default_config, NULL);
1031         parse_args(argc, argv, &opts);
1032         res = pick_revisions(&opts);
1033         if (res < 0)
1034                 die(_("cherry-pick failed"));
1035         return res;
1036 }