builtin/revert.c

   1 #include "cache.h"
   2 #include "builtin.h"
   3 #include "object.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "run-command.h"
   7 #include "exec_cmd.h"
   8 #include "utf8.h"
   9 #include "parse-options.h"
  10 #include "cache-tree.h"
  11 #include "diff.h"
  12 #include "revision.h"
  13 #include "rerere.h"
  14 #include "merge-recursive.h"
  15 #include "refs.h"
  16 #include "dir.h"
  17 #include "sequencer.h"
  18
  19 /*
  20  * This implements the builtins revert and cherry-pick.
  21  *
  22  * Copyright (c) 2007 Johannes E. Schindelin
  23  *
  24  * Based on git-revert.sh, which is
  25  *
  26  * Copyright (c) 2005 Linus Torvalds
  27  * Copyright (c) 2005 Junio C Hamano
  28  */
  29
  30 static const char * const revert_usage[] = {
  31         "git revert [options] <commit-ish>",
  32         "git revert <subcommand>",
  33         NULL
  34 };
  35
  36 static const char * const cherry_pick_usage[] = {
  37         "git cherry-pick [options] <commit-ish>",
  38         "git cherry-pick <subcommand>",
  39         NULL
  40 };
  41
  42 enum replay_action { REVERT, CHERRY_PICK };
  43 enum replay_subcommand {
  44         REPLAY_NONE,
  45         REPLAY_REMOVE_STATE,
  46         REPLAY_CONTINUE,
  47         REPLAY_ROLLBACK
  48 };
  49
  50 struct replay_opts {
  51         enum replay_action action;
  52         enum replay_subcommand subcommand;
  53
  54         /* Boolean options */
  55         int edit;
  56         int record_origin;
  57         int no_commit;
  58         int signoff;
  59         int allow_ff;
  60         int allow_rerere_auto;
  61
  62         int mainline;
  63         int commit_argc;
  64         const char **commit_argv;
  65
  66         /* Merge strategy */
  67         const char *strategy;
  68         const char **xopts;
  69         size_t xopts_nr, xopts_alloc;
  70 };
  71
  72 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  73
  74 static const char *action_name(const struct replay_opts *opts)
  75 {
  76         return opts->action == REVERT ? "revert" : "cherry-pick";
  77 }
  78
  79 static char *get_encoding(const char *message);
  80
  81 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
  82 {
  83         return opts->action == REVERT ? revert_usage : cherry_pick_usage;
  84 }
  85
  86 static int option_parse_x(const struct option *opt,
  87                           const char *arg, int unset)
  88 {
  89         struct replay_opts **opts_ptr = opt->value;
  90         struct replay_opts *opts = *opts_ptr;
  91
  92         if (unset)
  93                 return 0;
  94
  95         ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
  96         opts->xopts[opts->xopts_nr++] = xstrdup(arg);
  97         return 0;
  98 }
  99
 100 static void verify_opt_compatible(const char *me, const char *base_opt, ...)
 101 {
 102         const char *this_opt;
 103         va_list ap;
 104
 105         va_start(ap, base_opt);
 106         while ((this_opt = va_arg(ap, const char *))) {
 107                 if (va_arg(ap, int))
 108                         break;
 109         }
 110         va_end(ap);
 111
 112         if (this_opt)
 113                 die(_("%s: %s cannot be used with %s"), me, this_opt, base_opt);
 114 }
 115
 116 static void verify_opt_mutually_compatible(const char *me, ...)
 117 {
 118         const char *opt1, *opt2 = NULL;
 119         va_list ap;
 120
 121         va_start(ap, me);
 122         while ((opt1 = va_arg(ap, const char *))) {
 123                 if (va_arg(ap, int))
 124                         break;
 125         }
 126         if (opt1) {
 127                 while ((opt2 = va_arg(ap, const char *))) {
 128                         if (va_arg(ap, int))
 129                                 break;
 130                 }
 131         }
 132
 133         if (opt1 && opt2)
 134                 die(_("%s: %s cannot be used with %s"), me, opt1, opt2);
 135 }
 136
 137 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 138 {
 139         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
 140         const char *me = action_name(opts);
 141         int remove_state = 0;
 142         int contin = 0;
 143         int rollback = 0;
 144         struct option options[] = {
 145                 OPT_BOOLEAN(0, "quit", &remove_state, "end revert or cherry-pick sequence"),
 146                 OPT_BOOLEAN(0, "continue", &contin, "resume revert or cherry-pick sequence"),
 147                 OPT_BOOLEAN(0, "abort", &rollback, "cancel revert or cherry-pick sequence"),
 148                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
 149                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
 150                 OPT_NOOP_NOARG('r', NULL),
 151                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
 152                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
 153                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
 154                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
 155                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
 156                         "option for merge strategy", option_parse_x),
 157                 { OPTION_BOOLEAN, 0, "reset", &remove_state, NULL,
 158                         "alias for --quit (deprecated)",
 159                         PARSE_OPT_HIDDEN | PARSE_OPT_NOARG },
 160                 OPT_END(),
 161                 OPT_END(),
 162                 OPT_END(),
 163         };
 164
 165         if (opts->action == CHERRY_PICK) {
 166                 struct option cp_extra[] = {
 167                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 168                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
 169                         OPT_END(),
 170                 };
 171                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
 172                         die(_("program error"));
 173         }
 174
 175         opts->commit_argc = parse_options(argc, argv, NULL, options, usage_str,
 176                                         PARSE_OPT_KEEP_ARGV0 |
 177                                         PARSE_OPT_KEEP_UNKNOWN);
 178
 179         /* Check for incompatible subcommands */
 180         verify_opt_mutually_compatible(me,
 181                                 "--quit", remove_state,
 182                                 "--continue", contin,
 183                                 "--abort", rollback,
 184                                 NULL);
 185
 186         /* Set the subcommand */
 187         if (remove_state)
 188                 opts->subcommand = REPLAY_REMOVE_STATE;
 189         else if (contin)
 190                 opts->subcommand = REPLAY_CONTINUE;
 191         else if (rollback)
 192                 opts->subcommand = REPLAY_ROLLBACK;
 193         else
 194                 opts->subcommand = REPLAY_NONE;
 195
 196         /* Check for incompatible command line arguments */
 197         if (opts->subcommand != REPLAY_NONE) {
 198                 char *this_operation;
 199                 if (opts->subcommand == REPLAY_REMOVE_STATE)
 200                         this_operation = "--quit";
 201                 else if (opts->subcommand == REPLAY_CONTINUE)
 202                         this_operation = "--continue";
 203                 else {
 204                         assert(opts->subcommand == REPLAY_ROLLBACK);
 205                         this_operation = "--abort";
 206                 }
 207
 208                 verify_opt_compatible(me, this_operation,
 209                                 "--no-commit", opts->no_commit,
 210                                 "--signoff", opts->signoff,
 211                                 "--mainline", opts->mainline,
 212                                 "--strategy", opts->strategy ? 1 : 0,
 213                                 "--strategy-option", opts->xopts ? 1 : 0,
 214                                 "-x", opts->record_origin,
 215                                 "--ff", opts->allow_ff,
 216                                 NULL);
 217         }
 218
 219         else if (opts->commit_argc < 2)
 220                 usage_with_options(usage_str, options);
 221
 222         if (opts->allow_ff)
 223                 verify_opt_compatible(me, "--ff",
 224                                 "--signoff", opts->signoff,
 225                                 "--no-commit", opts->no_commit,
 226                                 "-x", opts->record_origin,
 227                                 "--edit", opts->edit,
 228                                 NULL);
 229         opts->commit_argv = argv;
 230 }
 231
 232 struct commit_message {
 233         char *parent_label;
 234         const char *label;
 235         const char *subject;
 236         char *reencoded_message;
 237         const char *message;
 238 };
 239
 240 static int get_message(struct commit *commit, struct commit_message *out)
 241 {
 242         const char *encoding;
 243         const char *abbrev, *subject;
 244         int abbrev_len, subject_len;
 245         char *q;
 246
 247         if (!commit->buffer)
 248                 return -1;
 249         encoding = get_encoding(commit->buffer);
 250         if (!encoding)
 251                 encoding = "UTF-8";
 252         if (!git_commit_encoding)
 253                 git_commit_encoding = "UTF-8";
 254
 255         out->reencoded_message = NULL;
 256         out->message = commit->buffer;
 257         if (strcmp(encoding, git_commit_encoding))
 258                 out->reencoded_message = reencode_string(commit->buffer,
 259                                         git_commit_encoding, encoding);
 260         if (out->reencoded_message)
 261                 out->message = out->reencoded_message;
 262
 263         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 264         abbrev_len = strlen(abbrev);
 265
 266         subject_len = find_commit_subject(out->message, &subject);
 267
 268         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 269                               strlen("... ") + subject_len + 1);
 270         q = out->parent_label;
 271         q = mempcpy(q, "parent of ", strlen("parent of "));
 272         out->label = q;
 273         q = mempcpy(q, abbrev, abbrev_len);
 274         q = mempcpy(q, "... ", strlen("... "));
 275         out->subject = q;
 276         q = mempcpy(q, subject, subject_len);
 277         *q = '\0';
 278         return 0;
 279 }
 280
 281 static void free_message(struct commit_message *msg)
 282 {
 283         free(msg->parent_label);
 284         free(msg->reencoded_message);
 285 }
 286
 287 static char *get_encoding(const char *message)
 288 {
 289         const char *p = message, *eol;
 290
 291         while (*p && *p != '\n') {
 292                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 293                         ; /* do nothing */
 294                 if (!prefixcmp(p, "encoding ")) {
 295                         char *result = xmalloc(eol - 8 - p);
 296                         strlcpy(result, p + 9, eol - 8 - p);
 297                         return result;
 298                 }
 299                 p = eol;
 300                 if (*p == '\n')
 301                         p++;
 302         }
 303         return NULL;
 304 }
 305
 306 static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
 307 {
 308         const char *filename;
 309         int fd;
 310         struct strbuf buf = STRBUF_INIT;
 311
 312         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 313
 314         filename = git_path(pseudoref);
 315         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 316         if (fd < 0)
 317                 die_errno(_("Could not open '%s' for writing"), filename);
 318         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 319                 die_errno(_("Could not write to '%s'"), filename);
 320         strbuf_release(&buf);
 321 }
 322
 323 static void print_advice(int show_hint)
 324 {
 325         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 326
 327         if (msg) {
 328                 fprintf(stderr, "%s\n", msg);
 329                 /*
 330                  * A conflict has occured but the porcelain
 331                  * (typically rebase --interactive) wants to take care
 332                  * of the commit itself so remove CHERRY_PICK_HEAD
 333                  */
 334                 unlink(git_path("CHERRY_PICK_HEAD"));
 335                 return;
 336         }
 337
 338         if (show_hint) {
 339                 advise("after resolving the conflicts, mark the corrected paths");
 340                 advise("with 'git add <paths>' or 'git rm <paths>'");
 341                 advise("and commit the result with 'git commit'");
 342         }
 343 }
 344
 345 static void write_message(struct strbuf *msgbuf, const char *filename)
 346 {
 347         static struct lock_file msg_file;
 348
 349         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 350                                                LOCK_DIE_ON_ERROR);
 351         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 352                 die_errno(_("Could not write to %s"), filename);
 353         strbuf_release(msgbuf);
 354         if (commit_lock_file(&msg_file) < 0)
 355                 die(_("Error wrapping up %s"), filename);
 356 }
 357
 358 static struct tree *empty_tree(void)
 359 {
 360         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 361 }
 362
 363 static int error_dirty_index(struct replay_opts *opts)
 364 {
 365         if (read_cache_unmerged())
 366                 return error_resolve_conflict(action_name(opts));
 367
 368         /* Different translation strings for cherry-pick and revert */
 369         if (opts->action == CHERRY_PICK)
 370                 error(_("Your local changes would be overwritten by cherry-pick."));
 371         else
 372                 error(_("Your local changes would be overwritten by revert."));
 373
 374         if (advice_commit_before_merge)
 375                 advise(_("Commit your changes or stash them to proceed."));
 376         return -1;
 377 }
 378
 379 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 380 {
 381         struct ref_lock *ref_lock;
 382
 383         read_cache();
 384         if (checkout_fast_forward(from, to))
 385                 exit(1); /* the callee should have complained already */
 386         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 387         return write_ref_sha1(ref_lock, to, "cherry-pick");
 388 }
 389
 390 static int do_recursive_merge(struct commit *base, struct commit *next,
 391                               const char *base_label, const char *next_label,
 392                               unsigned char *head, struct strbuf *msgbuf,
 393                               struct replay_opts *opts)
 394 {
 395         struct merge_options o;
 396         struct tree *result, *next_tree, *base_tree, *head_tree;
 397         int clean, index_fd;
 398         const char **xopt;
 399         static struct lock_file index_lock;
 400
 401         index_fd = hold_locked_index(&index_lock, 1);
 402
 403         read_cache();
 404
 405         init_merge_options(&o);
 406         o.ancestor = base ? base_label : "(empty tree)";
 407         o.branch1 = "HEAD";
 408         o.branch2 = next ? next_label : "(empty tree)";
 409
 410         head_tree = parse_tree_indirect(head);
 411         next_tree = next ? next->tree : empty_tree();
 412         base_tree = base ? base->tree : empty_tree();
 413
 414         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 415                 parse_merge_opt(&o, *xopt);
 416
 417         clean = merge_trees(&o,
 418                             head_tree,
 419                             next_tree, base_tree, &result);
 420
 421         if (active_cache_changed &&
 422             (write_cache(index_fd, active_cache, active_nr) ||
 423              commit_locked_index(&index_lock)))
 424                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 425                 die(_("%s: Unable to write new index file"), action_name(opts));
 426         rollback_lock_file(&index_lock);
 427
 428         if (!clean) {
 429                 int i;
 430                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 431                 for (i = 0; i < active_nr;) {
 432                         struct cache_entry *ce = active_cache[i++];
 433                         if (ce_stage(ce)) {
 434                                 strbuf_addch(msgbuf, '\t');
 435                                 strbuf_addstr(msgbuf, ce->name);
 436                                 strbuf_addch(msgbuf, '\n');
 437                                 while (i < active_nr && !strcmp(ce->name,
 438                                                 active_cache[i]->name))
 439                                         i++;
 440                         }
 441                 }
 442         }
 443
 444         return !clean;
 445 }
 446
 447 /*
 448  * If we are cherry-pick, and if the merge did not result in
 449  * hand-editing, we will hit this commit and inherit the original
 450  * author date and name.
 451  * If we are revert, or if our cherry-pick results in a hand merge,
 452  * we had better say that the current user is responsible for that.
 453  */
 454 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 455 {
 456         /* 6 is max possible length of our args array including NULL */
 457         const char *args[6];
 458         int i = 0;
 459
 460         args[i++] = "commit";
 461         args[i++] = "-n";
 462         if (opts->signoff)
 463                 args[i++] = "-s";
 464         if (!opts->edit) {
 465                 args[i++] = "-F";
 466                 args[i++] = defmsg;
 467         }
 468         args[i] = NULL;
 469
 470         return run_command_v_opt(args, RUN_GIT_CMD);
 471 }
 472
 473 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 474 {
 475         unsigned char head[20];
 476         struct commit *base, *next, *parent;
 477         const char *base_label, *next_label;
 478         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 479         char *defmsg = NULL;
 480         struct strbuf msgbuf = STRBUF_INIT;
 481         int res;
 482
 483         if (opts->no_commit) {
 484                 /*
 485                  * We do not intend to commit immediately.  We just want to
 486                  * merge the differences in, so let's compute the tree
 487                  * that represents the "current" state for merge-recursive
 488                  * to work on.
 489                  */
 490                 if (write_cache_as_tree(head, 0, NULL))
 491                         die (_("Your index file is unmerged."));
 492         } else {
 493                 if (get_sha1("HEAD", head))
 494                         return error(_("You do not have a valid HEAD"));
 495                 if (index_differs_from("HEAD", 0))
 496                         return error_dirty_index(opts);
 497         }
 498         discard_cache();
 499
 500         if (!commit->parents) {
 501                 parent = NULL;
 502         }
 503         else if (commit->parents->next) {
 504                 /* Reverting or cherry-picking a merge commit */
 505                 int cnt;
 506                 struct commit_list *p;
 507
 508                 if (!opts->mainline)
 509                         return error(_("Commit %s is a merge but no -m option was given."),
 510                                 sha1_to_hex(commit->object.sha1));
 511
 512                 for (cnt = 1, p = commit->parents;
 513                      cnt != opts->mainline && p;
 514                      cnt++)
 515                         p = p->next;
 516                 if (cnt != opts->mainline || !p)
 517                         return error(_("Commit %s does not have parent %d"),
 518                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 519                 parent = p->item;
 520         } else if (0 < opts->mainline)
 521                 return error(_("Mainline was specified but commit %s is not a merge."),
 522                         sha1_to_hex(commit->object.sha1));
 523         else
 524                 parent = commit->parents->item;
 525
 526         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 527                 return fast_forward_to(commit->object.sha1, head);
 528
 529         if (parent && parse_commit(parent) < 0)
 530                 /* TRANSLATORS: The first %s will be "revert" or
 531                    "cherry-pick", the second %s a SHA1 */
 532                 return error(_("%s: cannot parse parent commit %s"),
 533                         action_name(opts), sha1_to_hex(parent->object.sha1));
 534
 535         if (get_message(commit, &msg) != 0)
 536                 return error(_("Cannot get commit message for %s"),
 537                         sha1_to_hex(commit->object.sha1));
 538
 539         /*
 540          * "commit" is an existing commit.  We would want to apply
 541          * the difference it introduces since its first parent "prev"
 542          * on top of the current HEAD if we are cherry-pick.  Or the
 543          * reverse of it if we are revert.
 544          */
 545
 546         defmsg = git_pathdup("MERGE_MSG");
 547
 548         if (opts->action == REVERT) {
 549                 base = commit;
 550                 base_label = msg.label;
 551                 next = parent;
 552                 next_label = msg.parent_label;
 553                 strbuf_addstr(&msgbuf, "Revert \"");
 554                 strbuf_addstr(&msgbuf, msg.subject);
 555                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 556                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 557
 558                 if (commit->parents && commit->parents->next) {
 559                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 560                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 561                 }
 562                 strbuf_addstr(&msgbuf, ".\n");
 563         } else {
 564                 const char *p;
 565
 566                 base = parent;
 567                 base_label = msg.parent_label;
 568                 next = commit;
 569                 next_label = msg.label;
 570
 571                 /*
 572                  * Append the commit log message to msgbuf; it starts
 573                  * after the tree, parent, author, committer
 574                  * information followed by "\n\n".
 575                  */
 576                 p = strstr(msg.message, "\n\n");
 577                 if (p) {
 578                         p += 2;
 579                         strbuf_addstr(&msgbuf, p);
 580                 }
 581
 582                 if (opts->record_origin) {
 583                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 584                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 585                         strbuf_addstr(&msgbuf, ")\n");
 586                 }
 587         }
 588
 589         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
 590                 res = do_recursive_merge(base, next, base_label, next_label,
 591                                          head, &msgbuf, opts);
 592                 write_message(&msgbuf, defmsg);
 593         } else {
 594                 struct commit_list *common = NULL;
 595                 struct commit_list *remotes = NULL;
 596
 597                 write_message(&msgbuf, defmsg);
 598
 599                 commit_list_insert(base, &common);
 600                 commit_list_insert(next, &remotes);
 601                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 602                                         common, sha1_to_hex(head), remotes);
 603                 free_commit_list(common);
 604                 free_commit_list(remotes);
 605         }
 606
 607         /*
 608          * If the merge was clean or if it failed due to conflict, we write
 609          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 610          * However, if the merge did not even start, then we don't want to
 611          * write it at all.
 612          */
 613         if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
 614                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 615         if (opts->action == REVERT && ((opts->no_commit && res == 0) || res == 1))
 616                 write_cherry_pick_head(commit, "REVERT_HEAD");
 617
 618         if (res) {
 619                 error(opts->action == REVERT
 620                       ? _("could not revert %s... %s")
 621                       : _("could not apply %s... %s"),
 622                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 623                       msg.subject);
 624                 print_advice(res == 1);
 625                 rerere(opts->allow_rerere_auto);
 626         } else {
 627                 if (!opts->no_commit)
 628                         res = run_git_commit(defmsg, opts);
 629         }
 630
 631         free_message(&msg);
 632         free(defmsg);
 633
 634         return res;
 635 }
 636
 637 static void prepare_revs(struct rev_info *revs, struct replay_opts *opts)
 638 {
 639         int argc;
 640
 641         init_revisions(revs, NULL);
 642         revs->no_walk = 1;
 643         if (opts->action != REVERT)
 644                 revs->reverse = 1;
 645
 646         argc = setup_revisions(opts->commit_argc, opts->commit_argv, revs, NULL);
 647         if (argc > 1)
 648                 usage(*revert_or_cherry_pick_usage(opts));
 649
 650         if (prepare_revision_walk(revs))
 651                 die(_("revision walk setup failed"));
 652
 653         if (!revs->commits)
 654                 die(_("empty commit set passed"));
 655 }
 656
 657 static void read_and_refresh_cache(struct replay_opts *opts)
 658 {
 659         static struct lock_file index_lock;
 660         int index_fd = hold_locked_index(&index_lock, 0);
 661         if (read_index_preload(&the_index, NULL) < 0)
 662                 die(_("git %s: failed to read the index"), action_name(opts));
 663         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 664         if (the_index.cache_changed) {
 665                 if (write_index(&the_index, index_fd) ||
 666                     commit_locked_index(&index_lock))
 667                         die(_("git %s: failed to refresh the index"), action_name(opts));
 668         }
 669         rollback_lock_file(&index_lock);
 670 }
 671
 672 /*
 673  * Append a commit to the end of the commit_list.
 674  *
 675  * next starts by pointing to the variable that holds the head of an
 676  * empty commit_list, and is updated to point to the "next" field of
 677  * the last item on the list as new commits are appended.
 678  *
 679  * Usage example:
 680  *
 681  *     struct commit_list *list;
 682  *     struct commit_list **next = &list;
 683  *
 684  *     next = commit_list_append(c1, next);
 685  *     next = commit_list_append(c2, next);
 686  *     assert(commit_list_count(list) == 2);
 687  *     return list;
 688  */
 689 static struct commit_list **commit_list_append(struct commit *commit,
 690                                                struct commit_list **next)
 691 {
 692         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 693         new->item = commit;
 694         *next = new;
 695         new->next = NULL;
 696         return &new->next;
 697 }
 698
 699 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 700                 struct replay_opts *opts)
 701 {
 702         struct commit_list *cur = NULL;
 703         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 704         const char *sha1_abbrev = NULL;
 705         const char *action_str = opts->action == REVERT ? "revert" : "pick";
 706
 707         for (cur = todo_list; cur; cur = cur->next) {
 708                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 709                 if (get_message(cur->item, &msg))
 710                         return error(_("Cannot get commit message for %s"), sha1_abbrev);
 711                 strbuf_addf(buf, "%s %s %s\n", action_str, sha1_abbrev, msg.subject);
 712         }
 713         return 0;
 714 }
 715
 716 static struct commit *parse_insn_line(char *start, struct replay_opts *opts)
 717 {
 718         unsigned char commit_sha1[20];
 719         char sha1_abbrev[40];
 720         enum replay_action action;
 721         int insn_len = 0;
 722         char *p, *q;
 723
 724         if (!prefixcmp(start, "pick ")) {
 725                 action = CHERRY_PICK;
 726                 insn_len = strlen("pick");
 727                 p = start + insn_len + 1;
 728         } else if (!prefixcmp(start, "revert ")) {
 729                 action = REVERT;
 730                 insn_len = strlen("revert");
 731                 p = start + insn_len + 1;
 732         } else
 733                 return NULL;
 734
 735         q = strchr(p, ' ');
 736         if (!q)
 737                 return NULL;
 738         q++;
 739
 740         strlcpy(sha1_abbrev, p, q - p);
 741
 742         /*
 743          * Verify that the action matches up with the one in
 744          * opts; we don't support arbitrary instructions
 745          */
 746         if (action != opts->action) {
 747                 const char *action_str;
 748                 action_str = action == REVERT ? "revert" : "cherry-pick";
 749                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 750                 return NULL;
 751         }
 752
 753         if (get_sha1(sha1_abbrev, commit_sha1) < 0)
 754                 return NULL;
 755
 756         return lookup_commit_reference(commit_sha1);
 757 }
 758
 759 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 760                         struct replay_opts *opts)
 761 {
 762         struct commit_list **next = todo_list;
 763         struct commit *commit;
 764         char *p = buf;
 765         int i;
 766
 767         for (i = 1; *p; i++) {
 768                 commit = parse_insn_line(p, opts);
 769                 if (!commit)
 770                         return error(_("Could not parse line %d."), i);
 771                 next = commit_list_append(commit, next);
 772                 p = strchrnul(p, '\n');
 773                 if (*p)
 774                         p++;
 775         }
 776         if (!*todo_list)
 777                 return error(_("No commits parsed."));
 778         return 0;
 779 }
 780
 781 static void read_populate_todo(struct commit_list **todo_list,
 782                         struct replay_opts *opts)
 783 {
 784         const char *todo_file = git_path(SEQ_TODO_FILE);
 785         struct strbuf buf = STRBUF_INIT;
 786         int fd, res;
 787
 788         fd = open(todo_file, O_RDONLY);
 789         if (fd < 0)
 790                 die_errno(_("Could not open %s"), todo_file);
 791         if (strbuf_read(&buf, fd, 0) < 0) {
 792                 close(fd);
 793                 strbuf_release(&buf);
 794                 die(_("Could not read %s."), todo_file);
 795         }
 796         close(fd);
 797
 798         res = parse_insn_buffer(buf.buf, todo_list, opts);
 799         strbuf_release(&buf);
 800         if (res)
 801                 die(_("Unusable instruction sheet: %s"), todo_file);
 802 }
 803
 804 static int populate_opts_cb(const char *key, const char *value, void *data)
 805 {
 806         struct replay_opts *opts = data;
 807         int error_flag = 1;
 808
 809         if (!value)
 810                 error_flag = 0;
 811         else if (!strcmp(key, "options.no-commit"))
 812                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 813         else if (!strcmp(key, "options.edit"))
 814                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 815         else if (!strcmp(key, "options.signoff"))
 816                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 817         else if (!strcmp(key, "options.record-origin"))
 818                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 819         else if (!strcmp(key, "options.allow-ff"))
 820                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 821         else if (!strcmp(key, "options.mainline"))
 822                 opts->mainline = git_config_int(key, value);
 823         else if (!strcmp(key, "options.strategy"))
 824                 git_config_string(&opts->strategy, key, value);
 825         else if (!strcmp(key, "options.strategy-option")) {
 826                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 827                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 828         } else
 829                 return error(_("Invalid key: %s"), key);
 830
 831         if (!error_flag)
 832                 return error(_("Invalid value for %s: %s"), key, value);
 833
 834         return 0;
 835 }
 836
 837 static void read_populate_opts(struct replay_opts **opts_ptr)
 838 {
 839         const char *opts_file = git_path(SEQ_OPTS_FILE);
 840
 841         if (!file_exists(opts_file))
 842                 return;
 843         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 844                 die(_("Malformed options sheet: %s"), opts_file);
 845 }
 846
 847 static void walk_revs_populate_todo(struct commit_list **todo_list,
 848                                 struct replay_opts *opts)
 849 {
 850         struct rev_info revs;
 851         struct commit *commit;
 852         struct commit_list **next;
 853
 854         prepare_revs(&revs, opts);
 855
 856         next = todo_list;
 857         while ((commit = get_revision(&revs)))
 858                 next = commit_list_append(commit, next);
 859 }
 860
 861 static int create_seq_dir(void)
 862 {
 863         const char *seq_dir = git_path(SEQ_DIR);
 864
 865         if (file_exists(seq_dir)) {
 866                 error(_("a cherry-pick or revert is already in progress"));
 867                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 868                 return -1;
 869         }
 870         else if (mkdir(seq_dir, 0777) < 0)
 871                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 872         return 0;
 873 }
 874
 875 static void save_head(const char *head)
 876 {
 877         const char *head_file = git_path(SEQ_HEAD_FILE);
 878         static struct lock_file head_lock;
 879         struct strbuf buf = STRBUF_INIT;
 880         int fd;
 881
 882         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 883         strbuf_addf(&buf, "%s\n", head);
 884         if (write_in_full(fd, buf.buf, buf.len) < 0)
 885                 die_errno(_("Could not write to %s"), head_file);
 886         if (commit_lock_file(&head_lock) < 0)
 887                 die(_("Error wrapping up %s."), head_file);
 888 }
 889
 890 static int reset_for_rollback(const unsigned char *sha1)
 891 {
 892         const char *argv[4];    /* reset --merge <arg> + NULL */
 893         argv[0] = "reset";
 894         argv[1] = "--merge";
 895         argv[2] = sha1_to_hex(sha1);
 896         argv[3] = NULL;
 897         return run_command_v_opt(argv, RUN_GIT_CMD);
 898 }
 899
 900 static int rollback_single_pick(void)
 901 {
 902         unsigned char head_sha1[20];
 903
 904         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 905             !file_exists(git_path("REVERT_HEAD")))
 906                 return error(_("no cherry-pick or revert in progress"));
 907         if (!resolve_ref("HEAD", head_sha1, 0, NULL))
 908                 return error(_("cannot resolve HEAD"));
 909         if (is_null_sha1(head_sha1))
 910                 return error(_("cannot abort from a branch yet to be born"));
 911         return reset_for_rollback(head_sha1);
 912 }
 913
 914 static int sequencer_rollback(struct replay_opts *opts)
 915 {
 916         const char *filename;
 917         FILE *f;
 918         unsigned char sha1[20];
 919         struct strbuf buf = STRBUF_INIT;
 920
 921         filename = git_path(SEQ_HEAD_FILE);
 922         f = fopen(filename, "r");
 923         if (!f && errno == ENOENT) {
 924                 /*
 925                  * There is no multiple-cherry-pick in progress.
 926                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 927                  * a single-cherry-pick in progress, abort that.
 928                  */
 929                 return rollback_single_pick();
 930         }
 931         if (!f)
 932                 return error(_("cannot open %s: %s"), filename,
 933                                                 strerror(errno));
 934         if (strbuf_getline(&buf, f, '\n')) {
 935                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 936                         strerror(errno) : _("unexpected end of file"));
 937                 goto fail;
 938         }
 939         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 940                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 941                         filename);
 942                 goto fail;
 943         }
 944         if (reset_for_rollback(sha1))
 945                 goto fail;
 946         strbuf_release(&buf);
 947         fclose(f);
 948         return 0;
 949 fail:
 950         strbuf_release(&buf);
 951         fclose(f);
 952         return -1;
 953 }
 954
 955 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 956 {
 957         const char *todo_file = git_path(SEQ_TODO_FILE);
 958         static struct lock_file todo_lock;
 959         struct strbuf buf = STRBUF_INIT;
 960         int fd;
 961
 962         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 963         if (format_todo(&buf, todo_list, opts) < 0)
 964                 die(_("Could not format %s."), todo_file);
 965         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 966                 strbuf_release(&buf);
 967                 die_errno(_("Could not write to %s"), todo_file);
 968         }
 969         if (commit_lock_file(&todo_lock) < 0) {
 970                 strbuf_release(&buf);
 971                 die(_("Error wrapping up %s."), todo_file);
 972         }
 973         strbuf_release(&buf);
 974 }
 975
 976 static void save_opts(struct replay_opts *opts)
 977 {
 978         const char *opts_file = git_path(SEQ_OPTS_FILE);
 979
 980         if (opts->no_commit)
 981                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 982         if (opts->edit)
 983                 git_config_set_in_file(opts_file, "options.edit", "true");
 984         if (opts->signoff)
 985                 git_config_set_in_file(opts_file, "options.signoff", "true");
 986         if (opts->record_origin)
 987                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 988         if (opts->allow_ff)
 989                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 990         if (opts->mainline) {
 991                 struct strbuf buf = STRBUF_INIT;
 992                 strbuf_addf(&buf, "%d", opts->mainline);
 993                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 994                 strbuf_release(&buf);
 995         }
 996         if (opts->strategy)
 997                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 998         if (opts->xopts) {
 999                 int i;
1000                 for (i = 0; i < opts->xopts_nr; i++)
1001                         git_config_set_multivar_in_file(opts_file,
1002                                                         "options.strategy-option",
1003                                                         opts->xopts[i], "^$", 0);
1004         }
1005 }
1006
1007 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
1008 {
1009         struct commit_list *cur;
1010         int res;
1011
1012         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
1013         if (opts->allow_ff)
1014                 assert(!(opts->signoff || opts->no_commit ||
1015                                 opts->record_origin || opts->edit));
1016         read_and_refresh_cache(opts);
1017
1018         for (cur = todo_list; cur; cur = cur->next) {
1019                 save_todo(cur, opts);
1020                 res = do_pick_commit(cur->item, opts);
1021                 if (res) {
1022                         if (!cur->next)
1023                                 /*
1024                                  * An error was encountered while
1025                                  * picking the last commit; the
1026                                  * sequencer state is useless now --
1027                                  * the user simply needs to resolve
1028                                  * the conflict and commit
1029                                  */
1030                                 remove_sequencer_state(0);
1031                         return res;
1032                 }
1033         }
1034
1035         /*
1036          * Sequence of picks finished successfully; cleanup by
1037          * removing the .git/sequencer directory
1038          */
1039         remove_sequencer_state(1);
1040         return 0;
1041 }
1042
1043 static int pick_revisions(struct replay_opts *opts)
1044 {
1045         struct commit_list *todo_list = NULL;
1046         unsigned char sha1[20];
1047
1048         read_and_refresh_cache(opts);
1049
1050         /*
1051          * Decide what to do depending on the arguments; a fresh
1052          * cherry-pick should be handled differently from an existing
1053          * one that is being continued
1054          */
1055         if (opts->subcommand == REPLAY_REMOVE_STATE) {
1056                 remove_sequencer_state(1);
1057                 return 0;
1058         }
1059         if (opts->subcommand == REPLAY_ROLLBACK)
1060                 return sequencer_rollback(opts);
1061         if (opts->subcommand == REPLAY_CONTINUE) {
1062                 if (!file_exists(git_path(SEQ_TODO_FILE)))
1063                         return error(_("No %s in progress"), action_name(opts));
1064                 read_populate_opts(&opts);
1065                 read_populate_todo(&todo_list, opts);
1066
1067                 /* Verify that the conflict has been resolved */
1068                 if (!index_differs_from("HEAD", 0))
1069                         todo_list = todo_list->next;
1070                 return pick_commits(todo_list, opts);
1071         }
1072
1073         /*
1074          * Start a new cherry-pick/ revert sequence; but
1075          * first, make sure that an existing one isn't in
1076          * progress
1077          */
1078
1079         walk_revs_populate_todo(&todo_list, opts);
1080         if (create_seq_dir() < 0)
1081                 return -1;
1082         if (get_sha1("HEAD", sha1)) {
1083                 if (opts->action == REVERT)
1084                         return error(_("Can't revert as initial commit"));
1085                 return error(_("Can't cherry-pick into empty head"));
1086         }
1087         save_head(sha1_to_hex(sha1));
1088         save_opts(opts);
1089         return pick_commits(todo_list, opts);
1090 }
1091
1092 int cmd_revert(int argc, const char **argv, const char *prefix)
1093 {
1094         struct replay_opts opts;
1095         int res;
1096
1097         memset(&opts, 0, sizeof(opts));
1098         if (isatty(0))
1099                 opts.edit = 1;
1100         opts.action = REVERT;
1101         git_config(git_default_config, NULL);
1102         parse_args(argc, argv, &opts);
1103         res = pick_revisions(&opts);
1104         if (res < 0)
1105                 die(_("revert failed"));
1106         return res;
1107 }
1108
1109 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1110 {
1111         struct replay_opts opts;
1112         int res;
1113
1114         memset(&opts, 0, sizeof(opts));
1115         opts.action = CHERRY_PICK;
1116         git_config(git_default_config, NULL);
1117         parse_args(argc, argv, &opts);
1118         res = pick_revisions(&opts);
1119         if (res < 0)
1120                 die(_("cherry-pick failed"));
1121         return res;
1122 }