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 "wt-status.h"
   7 #include "run-command.h"
   8 #include "exec_cmd.h"
   9 #include "utf8.h"
  10 #include "parse-options.h"
  11 #include "cache-tree.h"
  12 #include "diff.h"
  13 #include "revision.h"
  14 #include "rerere.h"
  15 #include "merge-recursive.h"
  16 #include "refs.h"
  17
  18 /*
  19  * This implements the builtins revert and cherry-pick.
  20  *
  21  * Copyright (c) 2007 Johannes E. Schindelin
  22  *
  23  * Based on git-revert.sh, which is
  24  *
  25  * Copyright (c) 2005 Linus Torvalds
  26  * Copyright (c) 2005 Junio C Hamano
  27  */
  28
  29 static const char * const revert_usage[] = {
  30         "git revert [options] <commit-ish>",
  31         NULL
  32 };
  33
  34 static const char * const cherry_pick_usage[] = {
  35         "git cherry-pick [options] <commit-ish>",
  36         NULL
  37 };
  38
  39 static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
  40 static enum { REVERT, CHERRY_PICK } action;
  41 static struct commit *commit;
  42 static int commit_argc;
  43 static const char **commit_argv;
  44 static int allow_rerere_auto;
  45
  46 static const char *me;
  47
  48 /* Merge strategy. */
  49 static const char *strategy;
  50 static const char **xopts;
  51 static size_t xopts_nr, xopts_alloc;
  52
  53 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  54
  55 static char *get_encoding(const char *message);
  56
  57 static const char * const *revert_or_cherry_pick_usage(void)
  58 {
  59         return action == REVERT ? revert_usage : cherry_pick_usage;
  60 }
  61
  62 static int option_parse_x(const struct option *opt,
  63                           const char *arg, int unset)
  64 {
  65         if (unset)
  66                 return 0;
  67
  68         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
  69         xopts[xopts_nr++] = xstrdup(arg);
  70         return 0;
  71 }
  72
  73 static void parse_args(int argc, const char **argv)
  74 {
  75         const char * const * usage_str = revert_or_cherry_pick_usage();
  76         int noop;
  77         struct option options[] = {
  78                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  79                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  80                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  81                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  82                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  83                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  84                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
  85                 OPT_CALLBACK('X', "strategy-option", &xopts, "option",
  86                         "option for merge strategy", option_parse_x),
  87                 OPT_END(),
  88                 OPT_END(),
  89                 OPT_END(),
  90         };
  91
  92         if (action == CHERRY_PICK) {
  93                 struct option cp_extra[] = {
  94                         OPT_BOOLEAN('x', NULL, &no_replay, "append commit name"),
  95                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
  96                         OPT_END(),
  97                 };
  98                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
  99                         die(_("program error"));
 100         }
 101
 102         commit_argc = parse_options(argc, argv, NULL, options, usage_str,
 103                                     PARSE_OPT_KEEP_ARGV0 |
 104                                     PARSE_OPT_KEEP_UNKNOWN);
 105         if (commit_argc < 2)
 106                 usage_with_options(usage_str, options);
 107
 108         commit_argv = argv;
 109 }
 110
 111 struct commit_message {
 112         char *parent_label;
 113         const char *label;
 114         const char *subject;
 115         char *reencoded_message;
 116         const char *message;
 117 };
 118
 119 static int get_message(const char *raw_message, struct commit_message *out)
 120 {
 121         const char *encoding;
 122         const char *abbrev, *subject;
 123         int abbrev_len, subject_len;
 124         char *q;
 125
 126         if (!raw_message)
 127                 return -1;
 128         encoding = get_encoding(raw_message);
 129         if (!encoding)
 130                 encoding = "UTF-8";
 131         if (!git_commit_encoding)
 132                 git_commit_encoding = "UTF-8";
 133
 134         out->reencoded_message = NULL;
 135         out->message = raw_message;
 136         if (strcmp(encoding, git_commit_encoding))
 137                 out->reencoded_message = reencode_string(raw_message,
 138                                         git_commit_encoding, encoding);
 139         if (out->reencoded_message)
 140                 out->message = out->reencoded_message;
 141
 142         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 143         abbrev_len = strlen(abbrev);
 144
 145         subject_len = find_commit_subject(out->message, &subject);
 146
 147         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 148                               strlen("... ") + subject_len + 1);
 149         q = out->parent_label;
 150         q = mempcpy(q, "parent of ", strlen("parent of "));
 151         out->label = q;
 152         q = mempcpy(q, abbrev, abbrev_len);
 153         q = mempcpy(q, "... ", strlen("... "));
 154         out->subject = q;
 155         q = mempcpy(q, subject, subject_len);
 156         *q = '\0';
 157         return 0;
 158 }
 159
 160 static void free_message(struct commit_message *msg)
 161 {
 162         free(msg->parent_label);
 163         free(msg->reencoded_message);
 164 }
 165
 166 static char *get_encoding(const char *message)
 167 {
 168         const char *p = message, *eol;
 169
 170         if (!p)
 171                 die (_("Could not read commit message of %s"),
 172                                 sha1_to_hex(commit->object.sha1));
 173         while (*p && *p != '\n') {
 174                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 175                         ; /* do nothing */
 176                 if (!prefixcmp(p, "encoding ")) {
 177                         char *result = xmalloc(eol - 8 - p);
 178                         strlcpy(result, p + 9, eol - 8 - p);
 179                         return result;
 180                 }
 181                 p = eol;
 182                 if (*p == '\n')
 183                         p++;
 184         }
 185         return NULL;
 186 }
 187
 188 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 189 {
 190         const char *p = message;
 191         while (*p && (*p != '\n' || p[1] != '\n'))
 192                 p++;
 193
 194         if (!*p)
 195                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 196
 197         p += 2;
 198         strbuf_addstr(msgbuf, p);
 199 }
 200
 201 static void set_author_ident_env(const char *message)
 202 {
 203         const char *p = message;
 204         if (!p)
 205                 die (_("Could not read commit message of %s"),
 206                                 sha1_to_hex(commit->object.sha1));
 207         while (*p && *p != '\n') {
 208                 const char *eol;
 209
 210                 for (eol = p; *eol && *eol != '\n'; eol++)
 211                         ; /* do nothing */
 212                 if (!prefixcmp(p, "author ")) {
 213                         char *line, *pend, *email, *timestamp;
 214
 215                         p += 7;
 216                         line = xmemdupz(p, eol - p);
 217                         email = strchr(line, '<');
 218                         if (!email)
 219                                 die (_("Could not extract author email from %s"),
 220                                         sha1_to_hex(commit->object.sha1));
 221                         if (email == line)
 222                                 pend = line;
 223                         else
 224                                 for (pend = email; pend != line + 1 &&
 225                                                 isspace(pend[-1]); pend--);
 226                                         ; /* do nothing */
 227                         *pend = '\0';
 228                         email++;
 229                         timestamp = strchr(email, '>');
 230                         if (!timestamp)
 231                                 die (_("Could not extract author time from %s"),
 232                                         sha1_to_hex(commit->object.sha1));
 233                         *timestamp = '\0';
 234                         for (timestamp++; *timestamp && isspace(*timestamp);
 235                                         timestamp++)
 236                                 ; /* do nothing */
 237                         setenv("GIT_AUTHOR_NAME", line, 1);
 238                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 239                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 240                         free(line);
 241                         return;
 242                 }
 243                 p = eol;
 244                 if (*p == '\n')
 245                         p++;
 246         }
 247         die (_("No author information found in %s"),
 248                         sha1_to_hex(commit->object.sha1));
 249 }
 250
 251 static void advise(const char *advice, ...)
 252 {
 253         va_list params;
 254
 255         va_start(params, advice);
 256         vreportf("hint: ", advice, params);
 257         va_end(params);
 258 }
 259
 260 static void print_advice(void)
 261 {
 262         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 263
 264         if (msg) {
 265                 fprintf(stderr, "%s\n", msg);
 266                 return;
 267         }
 268
 269         advise("after resolving the conflicts, mark the corrected paths");
 270         advise("with 'git add <paths>' or 'git rm <paths>'");
 271
 272         if (action == CHERRY_PICK)
 273                 advise("and commit the result with 'git commit -c %s'",
 274                        find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 275 }
 276
 277 static void write_message(struct strbuf *msgbuf, const char *filename)
 278 {
 279         static struct lock_file msg_file;
 280
 281         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 282                                                LOCK_DIE_ON_ERROR);
 283         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 284                 die_errno(_("Could not write to %s."), filename);
 285         strbuf_release(msgbuf);
 286         if (commit_lock_file(&msg_file) < 0)
 287                 die(_("Error wrapping up %s"), filename);
 288 }
 289
 290 static struct tree *empty_tree(void)
 291 {
 292         struct tree *tree = xcalloc(1, sizeof(struct tree));
 293
 294         tree->object.parsed = 1;
 295         tree->object.type = OBJ_TREE;
 296         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 297         return tree;
 298 }
 299
 300 static NORETURN void die_dirty_index(const char *me)
 301 {
 302         if (read_cache_unmerged()) {
 303                 die_resolve_conflict(me);
 304         } else {
 305                 if (advice_commit_before_merge) {
 306                         if (action == REVERT)
 307                                 die(_("Your local changes would be overwritten by revert.\n"
 308                                           "Please, commit your changes or stash them to proceed."));
 309                         else
 310                                 die(_("Your local changes would be overwritten by cherry-pick.\n"
 311                                           "Please, commit your changes or stash them to proceed."));
 312                 } else {
 313                         if (action == REVERT)
 314                                 die(_("Your local changes would be overwritten by revert.\n"));
 315                         else
 316                                 die(_("Your local changes would be overwritten by cherry-pick.\n"));
 317                 }
 318         }
 319 }
 320
 321 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 322 {
 323         struct ref_lock *ref_lock;
 324
 325         read_cache();
 326         if (checkout_fast_forward(from, to))
 327                 exit(1); /* the callee should have complained already */
 328         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 329         return write_ref_sha1(ref_lock, to, "cherry-pick");
 330 }
 331
 332 static int do_recursive_merge(struct commit *base, struct commit *next,
 333                               const char *base_label, const char *next_label,
 334                               unsigned char *head, struct strbuf *msgbuf)
 335 {
 336         struct merge_options o;
 337         struct tree *result, *next_tree, *base_tree, *head_tree;
 338         int clean, index_fd;
 339         const char **xopt;
 340         static struct lock_file index_lock;
 341
 342         index_fd = hold_locked_index(&index_lock, 1);
 343
 344         read_cache();
 345
 346         init_merge_options(&o);
 347         o.ancestor = base ? base_label : "(empty tree)";
 348         o.branch1 = "HEAD";
 349         o.branch2 = next ? next_label : "(empty tree)";
 350
 351         head_tree = parse_tree_indirect(head);
 352         next_tree = next ? next->tree : empty_tree();
 353         base_tree = base ? base->tree : empty_tree();
 354
 355         for (xopt = xopts; xopt != xopts + xopts_nr; xopt++)
 356                 parse_merge_opt(&o, *xopt);
 357
 358         clean = merge_trees(&o,
 359                             head_tree,
 360                             next_tree, base_tree, &result);
 361
 362         if (active_cache_changed &&
 363             (write_cache(index_fd, active_cache, active_nr) ||
 364              commit_locked_index(&index_lock)))
 365                 die("%s: Unable to write new index file", me);
 366         rollback_lock_file(&index_lock);
 367
 368         if (!clean) {
 369                 int i;
 370                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 371                 for (i = 0; i < active_nr;) {
 372                         struct cache_entry *ce = active_cache[i++];
 373                         if (ce_stage(ce)) {
 374                                 strbuf_addch(msgbuf, '\t');
 375                                 strbuf_addstr(msgbuf, ce->name);
 376                                 strbuf_addch(msgbuf, '\n');
 377                                 while (i < active_nr && !strcmp(ce->name,
 378                                                 active_cache[i]->name))
 379                                         i++;
 380                         }
 381                 }
 382         }
 383
 384         return !clean;
 385 }
 386
 387 /*
 388  * If we are cherry-pick, and if the merge did not result in
 389  * hand-editing, we will hit this commit and inherit the original
 390  * author date and name.
 391  * If we are revert, or if our cherry-pick results in a hand merge,
 392  * we had better say that the current user is responsible for that.
 393  */
 394 static int run_git_commit(const char *defmsg)
 395 {
 396         /* 6 is max possible length of our args array including NULL */
 397         const char *args[6];
 398         int i = 0;
 399
 400         args[i++] = "commit";
 401         args[i++] = "-n";
 402         if (signoff)
 403                 args[i++] = "-s";
 404         if (!edit) {
 405                 args[i++] = "-F";
 406                 args[i++] = defmsg;
 407         }
 408         args[i] = NULL;
 409
 410         return run_command_v_opt(args, RUN_GIT_CMD);
 411 }
 412
 413 static int do_pick_commit(void)
 414 {
 415         unsigned char head[20];
 416         struct commit *base, *next, *parent;
 417         const char *base_label, *next_label;
 418         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 419         char *defmsg = NULL;
 420         struct strbuf msgbuf = STRBUF_INIT;
 421         int res;
 422
 423         if (no_commit) {
 424                 /*
 425                  * We do not intend to commit immediately.  We just want to
 426                  * merge the differences in, so let's compute the tree
 427                  * that represents the "current" state for merge-recursive
 428                  * to work on.
 429                  */
 430                 if (write_cache_as_tree(head, 0, NULL))
 431                         die (_("Your index file is unmerged."));
 432         } else {
 433                 if (get_sha1("HEAD", head))
 434                         die (_("You do not have a valid HEAD"));
 435                 if (index_differs_from("HEAD", 0))
 436                         die_dirty_index(me);
 437         }
 438         discard_cache();
 439
 440         if (!commit->parents) {
 441                 if (action == REVERT)
 442                         die (_("Cannot revert a root commit"));
 443                 parent = NULL;
 444         }
 445         else if (commit->parents->next) {
 446                 /* Reverting or cherry-picking a merge commit */
 447                 int cnt;
 448                 struct commit_list *p;
 449
 450                 if (!mainline)
 451                         die(_("Commit %s is a merge but no -m option was given."),
 452                             sha1_to_hex(commit->object.sha1));
 453
 454                 for (cnt = 1, p = commit->parents;
 455                      cnt != mainline && p;
 456                      cnt++)
 457                         p = p->next;
 458                 if (cnt != mainline || !p)
 459                         die(_("Commit %s does not have parent %d"),
 460                             sha1_to_hex(commit->object.sha1), mainline);
 461                 parent = p->item;
 462         } else if (0 < mainline)
 463                 die(_("Mainline was specified but commit %s is not a merge."),
 464                     sha1_to_hex(commit->object.sha1));
 465         else
 466                 parent = commit->parents->item;
 467
 468         if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
 469                 return fast_forward_to(commit->object.sha1, head);
 470
 471         if (parent && parse_commit(parent) < 0)
 472                 die("%s: cannot parse parent commit %s",
 473                     me, sha1_to_hex(parent->object.sha1));
 474
 475         if (get_message(commit->buffer, &msg) != 0)
 476                 die(_("Cannot get commit message for %s"),
 477                                 sha1_to_hex(commit->object.sha1));
 478
 479         /*
 480          * "commit" is an existing commit.  We would want to apply
 481          * the difference it introduces since its first parent "prev"
 482          * on top of the current HEAD if we are cherry-pick.  Or the
 483          * reverse of it if we are revert.
 484          */
 485
 486         defmsg = git_pathdup("MERGE_MSG");
 487
 488         if (action == REVERT) {
 489                 base = commit;
 490                 base_label = msg.label;
 491                 next = parent;
 492                 next_label = msg.parent_label;
 493                 strbuf_addstr(&msgbuf, "Revert \"");
 494                 strbuf_addstr(&msgbuf, msg.subject);
 495                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 496                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 497
 498                 if (commit->parents->next) {
 499                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 500                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 501                 }
 502                 strbuf_addstr(&msgbuf, ".\n");
 503         } else {
 504                 base = parent;
 505                 base_label = msg.parent_label;
 506                 next = commit;
 507                 next_label = msg.label;
 508                 set_author_ident_env(msg.message);
 509                 add_message_to_msg(&msgbuf, msg.message);
 510                 if (no_replay) {
 511                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 512                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 513                         strbuf_addstr(&msgbuf, ")\n");
 514                 }
 515         }
 516
 517         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 518                 res = do_recursive_merge(base, next, base_label, next_label,
 519                                          head, &msgbuf);
 520                 write_message(&msgbuf, defmsg);
 521         } else {
 522                 struct commit_list *common = NULL;
 523                 struct commit_list *remotes = NULL;
 524
 525                 write_message(&msgbuf, defmsg);
 526
 527                 commit_list_insert(base, &common);
 528                 commit_list_insert(next, &remotes);
 529                 res = try_merge_command(strategy, xopts_nr, xopts, common,
 530                                         sha1_to_hex(head), remotes);
 531                 free_commit_list(common);
 532                 free_commit_list(remotes);
 533         }
 534
 535         if (res) {
 536                 error("could not %s %s... %s",
 537                       action == REVERT ? "revert" : "apply",
 538                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 539                       msg.subject);
 540                 print_advice();
 541                 rerere(allow_rerere_auto);
 542         } else {
 543                 if (!no_commit)
 544                         res = run_git_commit(defmsg);
 545         }
 546
 547         free_message(&msg);
 548         free(defmsg);
 549
 550         return res;
 551 }
 552
 553 static void prepare_revs(struct rev_info *revs)
 554 {
 555         int argc;
 556
 557         init_revisions(revs, NULL);
 558         revs->no_walk = 1;
 559         if (action != REVERT)
 560                 revs->reverse = 1;
 561
 562         argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
 563         if (argc > 1)
 564                 usage(*revert_or_cherry_pick_usage());
 565
 566         if (prepare_revision_walk(revs))
 567                 die(_("revision walk setup failed"));
 568
 569         if (!revs->commits)
 570                 die(_("empty commit set passed"));
 571 }
 572
 573 static void read_and_refresh_cache(const char *me)
 574 {
 575         static struct lock_file index_lock;
 576         int index_fd = hold_locked_index(&index_lock, 0);
 577         if (read_index_preload(&the_index, NULL) < 0)
 578                 die(_("git %s: failed to read the index"), me);
 579         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 580         if (the_index.cache_changed) {
 581                 if (write_index(&the_index, index_fd) ||
 582                     commit_locked_index(&index_lock))
 583                         die(_("git %s: failed to refresh the index"), me);
 584         }
 585         rollback_lock_file(&index_lock);
 586 }
 587
 588 static int revert_or_cherry_pick(int argc, const char **argv)
 589 {
 590         struct rev_info revs;
 591
 592         git_config(git_default_config, NULL);
 593         me = action == REVERT ? "revert" : "cherry-pick";
 594         setenv(GIT_REFLOG_ACTION, me, 0);
 595         parse_args(argc, argv);
 596
 597         if (allow_ff) {
 598                 if (signoff)
 599                         die(_("cherry-pick --ff cannot be used with --signoff"));
 600                 if (no_commit)
 601                         die(_("cherry-pick --ff cannot be used with --no-commit"));
 602                 if (no_replay)
 603                         die(_("cherry-pick --ff cannot be used with -x"));
 604                 if (edit)
 605                         die(_("cherry-pick --ff cannot be used with --edit"));
 606         }
 607
 608         read_and_refresh_cache(me);
 609
 610         prepare_revs(&revs);
 611
 612         while ((commit = get_revision(&revs))) {
 613                 int res = do_pick_commit();
 614                 if (res)
 615                         return res;
 616         }
 617
 618         return 0;
 619 }
 620
 621 int cmd_revert(int argc, const char **argv, const char *prefix)
 622 {
 623         if (isatty(0))
 624                 edit = 1;
 625         action = REVERT;
 626         return revert_or_cherry_pick(argc, argv);
 627 }
 628
 629 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 630 {
 631         action = CHERRY_PICK;
 632         return revert_or_cherry_pick(argc, argv);
 633 }