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
  17 /*
  18  * This implements the builtins revert and cherry-pick.
  19  *
  20  * Copyright (c) 2007 Johannes E. Schindelin
  21  *
  22  * Based on git-revert.sh, which is
  23  *
  24  * Copyright (c) 2005 Linus Torvalds
  25  * Copyright (c) 2005 Junio C Hamano
  26  */
  27
  28 static const char * const revert_usage[] = {
  29         "git revert [options] <commit-ish>",
  30         NULL
  31 };
  32
  33 static const char * const cherry_pick_usage[] = {
  34         "git cherry-pick [options] <commit-ish>",
  35         NULL
  36 };
  37
  38 enum replay_action { REVERT, CHERRY_PICK };
  39
  40 struct replay_opts {
  41         enum replay_action action;
  42
  43         /* Boolean options */
  44         int edit;
  45         int record_origin;
  46         int no_commit;
  47         int signoff;
  48         int allow_ff;
  49         int allow_rerere_auto;
  50
  51         int mainline;
  52         int commit_argc;
  53         const char **commit_argv;
  54
  55         /* Merge strategy */
  56         const char *strategy;
  57         const char **xopts;
  58         size_t xopts_nr, xopts_alloc;
  59 };
  60
  61 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  62
  63 static const char *action_name(const struct replay_opts *opts)
  64 {
  65         return opts->action == REVERT ? "revert" : "cherry-pick";
  66 }
  67
  68 static char *get_encoding(const char *message);
  69
  70 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
  71 {
  72         return opts->action == REVERT ? revert_usage : cherry_pick_usage;
  73 }
  74
  75 static int option_parse_x(const struct option *opt,
  76                           const char *arg, int unset)
  77 {
  78         struct replay_opts **opts_ptr = opt->value;
  79         struct replay_opts *opts = *opts_ptr;
  80
  81         if (unset)
  82                 return 0;
  83
  84         ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
  85         opts->xopts[opts->xopts_nr++] = xstrdup(arg);
  86         return 0;
  87 }
  88
  89 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
  90 {
  91         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
  92         int noop;
  93         struct option options[] = {
  94                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
  95                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
  96                 { OPTION_BOOLEAN, 'r', NULL, &noop, NULL, "no-op (backward compatibility)",
  97                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, NULL, 0 },
  98                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
  99                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
 100                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
 101                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
 102                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
 103                         "option for merge strategy", option_parse_x),
 104                 OPT_END(),
 105                 OPT_END(),
 106                 OPT_END(),
 107         };
 108
 109         if (opts->action == CHERRY_PICK) {
 110                 struct option cp_extra[] = {
 111                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 112                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
 113                         OPT_END(),
 114                 };
 115                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
 116                         die(_("program error"));
 117         }
 118
 119         opts->commit_argc = parse_options(argc, argv, NULL, options, usage_str,
 120                                         PARSE_OPT_KEEP_ARGV0 |
 121                                         PARSE_OPT_KEEP_UNKNOWN);
 122         if (opts->commit_argc < 2)
 123                 usage_with_options(usage_str, options);
 124
 125         opts->commit_argv = argv;
 126 }
 127
 128 struct commit_message {
 129         char *parent_label;
 130         const char *label;
 131         const char *subject;
 132         char *reencoded_message;
 133         const char *message;
 134 };
 135
 136 static int get_message(struct commit *commit, struct commit_message *out)
 137 {
 138         const char *encoding;
 139         const char *abbrev, *subject;
 140         int abbrev_len, subject_len;
 141         char *q;
 142
 143         if (!commit->buffer)
 144                 return -1;
 145         encoding = get_encoding(commit->buffer);
 146         if (!encoding)
 147                 encoding = "UTF-8";
 148         if (!git_commit_encoding)
 149                 git_commit_encoding = "UTF-8";
 150
 151         out->reencoded_message = NULL;
 152         out->message = commit->buffer;
 153         if (strcmp(encoding, git_commit_encoding))
 154                 out->reencoded_message = reencode_string(commit->buffer,
 155                                         git_commit_encoding, encoding);
 156         if (out->reencoded_message)
 157                 out->message = out->reencoded_message;
 158
 159         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 160         abbrev_len = strlen(abbrev);
 161
 162         subject_len = find_commit_subject(out->message, &subject);
 163
 164         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 165                               strlen("... ") + subject_len + 1);
 166         q = out->parent_label;
 167         q = mempcpy(q, "parent of ", strlen("parent of "));
 168         out->label = q;
 169         q = mempcpy(q, abbrev, abbrev_len);
 170         q = mempcpy(q, "... ", strlen("... "));
 171         out->subject = q;
 172         q = mempcpy(q, subject, subject_len);
 173         *q = '\0';
 174         return 0;
 175 }
 176
 177 static void free_message(struct commit_message *msg)
 178 {
 179         free(msg->parent_label);
 180         free(msg->reencoded_message);
 181 }
 182
 183 static char *get_encoding(const char *message)
 184 {
 185         const char *p = message, *eol;
 186
 187         while (*p && *p != '\n') {
 188                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 189                         ; /* do nothing */
 190                 if (!prefixcmp(p, "encoding ")) {
 191                         char *result = xmalloc(eol - 8 - p);
 192                         strlcpy(result, p + 9, eol - 8 - p);
 193                         return result;
 194                 }
 195                 p = eol;
 196                 if (*p == '\n')
 197                         p++;
 198         }
 199         return NULL;
 200 }
 201
 202 static void write_cherry_pick_head(struct commit *commit)
 203 {
 204         int fd;
 205         struct strbuf buf = STRBUF_INIT;
 206
 207         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 208
 209         fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
 210         if (fd < 0)
 211                 die_errno(_("Could not open '%s' for writing"),
 212                           git_path("CHERRY_PICK_HEAD"));
 213         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 214                 die_errno(_("Could not write to '%s'"), git_path("CHERRY_PICK_HEAD"));
 215         strbuf_release(&buf);
 216 }
 217
 218 static void print_advice(void)
 219 {
 220         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 221
 222         if (msg) {
 223                 fprintf(stderr, "%s\n", msg);
 224                 /*
 225                  * A conflict has occured but the porcelain
 226                  * (typically rebase --interactive) wants to take care
 227                  * of the commit itself so remove CHERRY_PICK_HEAD
 228                  */
 229                 unlink(git_path("CHERRY_PICK_HEAD"));
 230                 return;
 231         }
 232
 233         advise("after resolving the conflicts, mark the corrected paths");
 234         advise("with 'git add <paths>' or 'git rm <paths>'");
 235         advise("and commit the result with 'git commit'");
 236 }
 237
 238 static void write_message(struct strbuf *msgbuf, const char *filename)
 239 {
 240         static struct lock_file msg_file;
 241
 242         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 243                                                LOCK_DIE_ON_ERROR);
 244         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 245                 die_errno(_("Could not write to %s."), filename);
 246         strbuf_release(msgbuf);
 247         if (commit_lock_file(&msg_file) < 0)
 248                 die(_("Error wrapping up %s"), filename);
 249 }
 250
 251 static struct tree *empty_tree(void)
 252 {
 253         struct tree *tree = xcalloc(1, sizeof(struct tree));
 254
 255         tree->object.parsed = 1;
 256         tree->object.type = OBJ_TREE;
 257         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 258         return tree;
 259 }
 260
 261 static NORETURN void die_dirty_index(struct replay_opts *opts)
 262 {
 263         if (read_cache_unmerged()) {
 264                 die_resolve_conflict(action_name(opts));
 265         } else {
 266                 if (advice_commit_before_merge) {
 267                         if (opts->action == REVERT)
 268                                 die(_("Your local changes would be overwritten by revert.\n"
 269                                           "Please, commit your changes or stash them to proceed."));
 270                         else
 271                                 die(_("Your local changes would be overwritten by cherry-pick.\n"
 272                                           "Please, commit your changes or stash them to proceed."));
 273                 } else {
 274                         if (opts->action == REVERT)
 275                                 die(_("Your local changes would be overwritten by revert.\n"));
 276                         else
 277                                 die(_("Your local changes would be overwritten by cherry-pick.\n"));
 278                 }
 279         }
 280 }
 281
 282 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 283 {
 284         struct ref_lock *ref_lock;
 285
 286         read_cache();
 287         if (checkout_fast_forward(from, to))
 288                 exit(1); /* the callee should have complained already */
 289         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 290         return write_ref_sha1(ref_lock, to, "cherry-pick");
 291 }
 292
 293 static int do_recursive_merge(struct commit *base, struct commit *next,
 294                               const char *base_label, const char *next_label,
 295                               unsigned char *head, struct strbuf *msgbuf,
 296                               struct replay_opts *opts)
 297 {
 298         struct merge_options o;
 299         struct tree *result, *next_tree, *base_tree, *head_tree;
 300         int clean, index_fd;
 301         const char **xopt;
 302         static struct lock_file index_lock;
 303
 304         index_fd = hold_locked_index(&index_lock, 1);
 305
 306         read_cache();
 307
 308         init_merge_options(&o);
 309         o.ancestor = base ? base_label : "(empty tree)";
 310         o.branch1 = "HEAD";
 311         o.branch2 = next ? next_label : "(empty tree)";
 312
 313         head_tree = parse_tree_indirect(head);
 314         next_tree = next ? next->tree : empty_tree();
 315         base_tree = base ? base->tree : empty_tree();
 316
 317         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 318                 parse_merge_opt(&o, *xopt);
 319
 320         clean = merge_trees(&o,
 321                             head_tree,
 322                             next_tree, base_tree, &result);
 323
 324         if (active_cache_changed &&
 325             (write_cache(index_fd, active_cache, active_nr) ||
 326              commit_locked_index(&index_lock)))
 327                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 328                 die(_("%s: Unable to write new index file"), action_name(opts));
 329         rollback_lock_file(&index_lock);
 330
 331         if (!clean) {
 332                 int i;
 333                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 334                 for (i = 0; i < active_nr;) {
 335                         struct cache_entry *ce = active_cache[i++];
 336                         if (ce_stage(ce)) {
 337                                 strbuf_addch(msgbuf, '\t');
 338                                 strbuf_addstr(msgbuf, ce->name);
 339                                 strbuf_addch(msgbuf, '\n');
 340                                 while (i < active_nr && !strcmp(ce->name,
 341                                                 active_cache[i]->name))
 342                                         i++;
 343                         }
 344                 }
 345         }
 346
 347         return !clean;
 348 }
 349
 350 /*
 351  * If we are cherry-pick, and if the merge did not result in
 352  * hand-editing, we will hit this commit and inherit the original
 353  * author date and name.
 354  * If we are revert, or if our cherry-pick results in a hand merge,
 355  * we had better say that the current user is responsible for that.
 356  */
 357 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 358 {
 359         /* 6 is max possible length of our args array including NULL */
 360         const char *args[6];
 361         int i = 0;
 362
 363         args[i++] = "commit";
 364         args[i++] = "-n";
 365         if (opts->signoff)
 366                 args[i++] = "-s";
 367         if (!opts->edit) {
 368                 args[i++] = "-F";
 369                 args[i++] = defmsg;
 370         }
 371         args[i] = NULL;
 372
 373         return run_command_v_opt(args, RUN_GIT_CMD);
 374 }
 375
 376 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 377 {
 378         unsigned char head[20];
 379         struct commit *base, *next, *parent;
 380         const char *base_label, *next_label;
 381         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 382         char *defmsg = NULL;
 383         struct strbuf msgbuf = STRBUF_INIT;
 384         int res;
 385
 386         if (opts->no_commit) {
 387                 /*
 388                  * We do not intend to commit immediately.  We just want to
 389                  * merge the differences in, so let's compute the tree
 390                  * that represents the "current" state for merge-recursive
 391                  * to work on.
 392                  */
 393                 if (write_cache_as_tree(head, 0, NULL))
 394                         die (_("Your index file is unmerged."));
 395         } else {
 396                 if (get_sha1("HEAD", head))
 397                         die (_("You do not have a valid HEAD"));
 398                 if (index_differs_from("HEAD", 0))
 399                         die_dirty_index(opts);
 400         }
 401         discard_cache();
 402
 403         if (!commit->parents) {
 404                 parent = NULL;
 405         }
 406         else if (commit->parents->next) {
 407                 /* Reverting or cherry-picking a merge commit */
 408                 int cnt;
 409                 struct commit_list *p;
 410
 411                 if (!opts->mainline)
 412                         die(_("Commit %s is a merge but no -m option was given."),
 413                             sha1_to_hex(commit->object.sha1));
 414
 415                 for (cnt = 1, p = commit->parents;
 416                      cnt != opts->mainline && p;
 417                      cnt++)
 418                         p = p->next;
 419                 if (cnt != opts->mainline || !p)
 420                         die(_("Commit %s does not have parent %d"),
 421                             sha1_to_hex(commit->object.sha1), opts->mainline);
 422                 parent = p->item;
 423         } else if (0 < opts->mainline)
 424                 die(_("Mainline was specified but commit %s is not a merge."),
 425                     sha1_to_hex(commit->object.sha1));
 426         else
 427                 parent = commit->parents->item;
 428
 429         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 430                 return fast_forward_to(commit->object.sha1, head);
 431
 432         if (parent && parse_commit(parent) < 0)
 433                 /* TRANSLATORS: The first %s will be "revert" or
 434                    "cherry-pick", the second %s a SHA1 */
 435                 die(_("%s: cannot parse parent commit %s"),
 436                     action_name(opts), sha1_to_hex(parent->object.sha1));
 437
 438         if (get_message(commit, &msg) != 0)
 439                 die(_("Cannot get commit message for %s"),
 440                                 sha1_to_hex(commit->object.sha1));
 441
 442         /*
 443          * "commit" is an existing commit.  We would want to apply
 444          * the difference it introduces since its first parent "prev"
 445          * on top of the current HEAD if we are cherry-pick.  Or the
 446          * reverse of it if we are revert.
 447          */
 448
 449         defmsg = git_pathdup("MERGE_MSG");
 450
 451         if (opts->action == REVERT) {
 452                 base = commit;
 453                 base_label = msg.label;
 454                 next = parent;
 455                 next_label = msg.parent_label;
 456                 strbuf_addstr(&msgbuf, "Revert \"");
 457                 strbuf_addstr(&msgbuf, msg.subject);
 458                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 459                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 460
 461                 if (commit->parents && commit->parents->next) {
 462                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 463                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 464                 }
 465                 strbuf_addstr(&msgbuf, ".\n");
 466         } else {
 467                 const char *p;
 468
 469                 base = parent;
 470                 base_label = msg.parent_label;
 471                 next = commit;
 472                 next_label = msg.label;
 473
 474                 /*
 475                  * Append the commit log message to msgbuf; it starts
 476                  * after the tree, parent, author, committer
 477                  * information followed by "\n\n".
 478                  */
 479                 p = strstr(msg.message, "\n\n");
 480                 if (p) {
 481                         p += 2;
 482                         strbuf_addstr(&msgbuf, p);
 483                 }
 484
 485                 if (opts->record_origin) {
 486                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 487                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 488                         strbuf_addstr(&msgbuf, ")\n");
 489                 }
 490                 if (!opts->no_commit)
 491                         write_cherry_pick_head(commit);
 492         }
 493
 494         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
 495                 res = do_recursive_merge(base, next, base_label, next_label,
 496                                          head, &msgbuf, opts);
 497                 write_message(&msgbuf, defmsg);
 498         } else {
 499                 struct commit_list *common = NULL;
 500                 struct commit_list *remotes = NULL;
 501
 502                 write_message(&msgbuf, defmsg);
 503
 504                 commit_list_insert(base, &common);
 505                 commit_list_insert(next, &remotes);
 506                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 507                                         common, sha1_to_hex(head), remotes);
 508                 free_commit_list(common);
 509                 free_commit_list(remotes);
 510         }
 511
 512         if (res) {
 513                 error(opts->action == REVERT
 514                       ? _("could not revert %s... %s")
 515                       : _("could not apply %s... %s"),
 516                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 517                       msg.subject);
 518                 print_advice();
 519                 rerere(opts->allow_rerere_auto);
 520         } else {
 521                 if (!opts->no_commit)
 522                         res = run_git_commit(defmsg, opts);
 523         }
 524
 525         free_message(&msg);
 526         free(defmsg);
 527
 528         return res;
 529 }
 530
 531 static void prepare_revs(struct rev_info *revs, struct replay_opts *opts)
 532 {
 533         int argc;
 534
 535         init_revisions(revs, NULL);
 536         revs->no_walk = 1;
 537         if (opts->action != REVERT)
 538                 revs->reverse = 1;
 539
 540         argc = setup_revisions(opts->commit_argc, opts->commit_argv, revs, NULL);
 541         if (argc > 1)
 542                 usage(*revert_or_cherry_pick_usage(opts));
 543
 544         if (prepare_revision_walk(revs))
 545                 die(_("revision walk setup failed"));
 546
 547         if (!revs->commits)
 548                 die(_("empty commit set passed"));
 549 }
 550
 551 static void read_and_refresh_cache(struct replay_opts *opts)
 552 {
 553         static struct lock_file index_lock;
 554         int index_fd = hold_locked_index(&index_lock, 0);
 555         if (read_index_preload(&the_index, NULL) < 0)
 556                 die(_("git %s: failed to read the index"), action_name(opts));
 557         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 558         if (the_index.cache_changed) {
 559                 if (write_index(&the_index, index_fd) ||
 560                     commit_locked_index(&index_lock))
 561                         die(_("git %s: failed to refresh the index"), action_name(opts));
 562         }
 563         rollback_lock_file(&index_lock);
 564 }
 565
 566 static int pick_commits(struct replay_opts *opts)
 567 {
 568         struct rev_info revs;
 569         struct commit *commit;
 570
 571         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 572         if (opts->allow_ff) {
 573                 if (opts->signoff)
 574                         die(_("cherry-pick --ff cannot be used with --signoff"));
 575                 if (opts->no_commit)
 576                         die(_("cherry-pick --ff cannot be used with --no-commit"));
 577                 if (opts->record_origin)
 578                         die(_("cherry-pick --ff cannot be used with -x"));
 579                 if (opts->edit)
 580                         die(_("cherry-pick --ff cannot be used with --edit"));
 581         }
 582
 583         read_and_refresh_cache(opts);
 584
 585         prepare_revs(&revs, opts);
 586
 587         while ((commit = get_revision(&revs))) {
 588                 int res = do_pick_commit(commit, opts);
 589                 if (res)
 590                         return res;
 591         }
 592
 593         return 0;
 594 }
 595
 596 int cmd_revert(int argc, const char **argv, const char *prefix)
 597 {
 598         struct replay_opts opts;
 599
 600         memset(&opts, 0, sizeof(opts));
 601         if (isatty(0))
 602                 opts.edit = 1;
 603         opts.action = REVERT;
 604         git_config(git_default_config, NULL);
 605         parse_args(argc, argv, &opts);
 606         return pick_commits(&opts);
 607 }
 608
 609 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 610 {
 611         struct replay_opts opts;
 612
 613         memset(&opts, 0, sizeof(opts));
 614         opts.action = CHERRY_PICK;
 615         git_config(git_default_config, NULL);
 616         parse_args(argc, argv, &opts);
 617         return pick_commits(&opts);
 618 }