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 static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
  39 static enum { REVERT, CHERRY_PICK } action;
  40 static struct commit *commit;
  41 static int commit_argc;
  42 static const char **commit_argv;
  43 static int allow_rerere_auto;
  44
  45 static const char *me;
  46
  47 /* Merge strategy. */
  48 static const char *strategy;
  49 static const char **xopts;
  50 static size_t xopts_nr, xopts_alloc;
  51
  52 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  53
  54 static char *get_encoding(const char *message);
  55
  56 static const char * const *revert_or_cherry_pick_usage(void)
  57 {
  58         return action == REVERT ? revert_usage : cherry_pick_usage;
  59 }
  60
  61 static int option_parse_x(const struct option *opt,
  62                           const char *arg, int unset)
  63 {
  64         if (unset)
  65                 return 0;
  66
  67         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
  68         xopts[xopts_nr++] = xstrdup(arg);
  69         return 0;
  70 }
  71
  72 static void parse_args(int argc, const char **argv)
  73 {
  74         const char * const * usage_str = revert_or_cherry_pick_usage();
  75         int noop;
  76         struct option options[] = {
  77                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  78                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  79                 { OPTION_BOOLEAN, 'r', NULL, &noop, NULL, "no-op (backward compatibility)",
  80                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, NULL, 0 },
  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 write_cherry_pick_head(void)
 202 {
 203         int fd;
 204         struct strbuf buf = STRBUF_INIT;
 205
 206         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 207
 208         fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
 209         if (fd < 0)
 210                 die_errno(_("Could not open '%s' for writing"),
 211                           git_path("CHERRY_PICK_HEAD"));
 212         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 213                 die_errno(_("Could not write to '%s'"), git_path("CHERRY_PICK_HEAD"));
 214         strbuf_release(&buf);
 215 }
 216
 217 static void advise(const char *advice, ...)
 218 {
 219         va_list params;
 220
 221         va_start(params, advice);
 222         vreportf("hint: ", advice, params);
 223         va_end(params);
 224 }
 225
 226 static void print_advice(int show_hint)
 227 {
 228         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 229
 230         if (msg) {
 231                 fprintf(stderr, "%s\n", msg);
 232                 /*
 233                  * A conflict has occured but the porcelain
 234                  * (typically rebase --interactive) wants to take care
 235                  * of the commit itself so remove CHERRY_PICK_HEAD
 236                  */
 237                 unlink(git_path("CHERRY_PICK_HEAD"));
 238                 return;
 239         }
 240
 241         if (show_hint) {
 242                 advise("after resolving the conflicts, mark the corrected paths");
 243                 advise("with 'git add <paths>' or 'git rm <paths>'");
 244                 advise("and commit the result with 'git commit'");
 245         }
 246 }
 247
 248 static void write_message(struct strbuf *msgbuf, const char *filename)
 249 {
 250         static struct lock_file msg_file;
 251
 252         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 253                                                LOCK_DIE_ON_ERROR);
 254         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 255                 die_errno(_("Could not write to %s."), filename);
 256         strbuf_release(msgbuf);
 257         if (commit_lock_file(&msg_file) < 0)
 258                 die(_("Error wrapping up %s"), filename);
 259 }
 260
 261 static struct tree *empty_tree(void)
 262 {
 263         struct tree *tree = xcalloc(1, sizeof(struct tree));
 264
 265         tree->object.parsed = 1;
 266         tree->object.type = OBJ_TREE;
 267         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 268         return tree;
 269 }
 270
 271 static NORETURN void die_dirty_index(const char *me)
 272 {
 273         if (read_cache_unmerged()) {
 274                 die_resolve_conflict(me);
 275         } else {
 276                 if (advice_commit_before_merge) {
 277                         if (action == REVERT)
 278                                 die(_("Your local changes would be overwritten by revert.\n"
 279                                           "Please, commit your changes or stash them to proceed."));
 280                         else
 281                                 die(_("Your local changes would be overwritten by cherry-pick.\n"
 282                                           "Please, commit your changes or stash them to proceed."));
 283                 } else {
 284                         if (action == REVERT)
 285                                 die(_("Your local changes would be overwritten by revert.\n"));
 286                         else
 287                                 die(_("Your local changes would be overwritten by cherry-pick.\n"));
 288                 }
 289         }
 290 }
 291
 292 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 293 {
 294         struct ref_lock *ref_lock;
 295
 296         read_cache();
 297         if (checkout_fast_forward(from, to))
 298                 exit(1); /* the callee should have complained already */
 299         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 300         return write_ref_sha1(ref_lock, to, "cherry-pick");
 301 }
 302
 303 static int do_recursive_merge(struct commit *base, struct commit *next,
 304                               const char *base_label, const char *next_label,
 305                               unsigned char *head, struct strbuf *msgbuf)
 306 {
 307         struct merge_options o;
 308         struct tree *result, *next_tree, *base_tree, *head_tree;
 309         int clean, index_fd;
 310         const char **xopt;
 311         static struct lock_file index_lock;
 312
 313         index_fd = hold_locked_index(&index_lock, 1);
 314
 315         read_cache();
 316
 317         init_merge_options(&o);
 318         o.ancestor = base ? base_label : "(empty tree)";
 319         o.branch1 = "HEAD";
 320         o.branch2 = next ? next_label : "(empty tree)";
 321
 322         head_tree = parse_tree_indirect(head);
 323         next_tree = next ? next->tree : empty_tree();
 324         base_tree = base ? base->tree : empty_tree();
 325
 326         for (xopt = xopts; xopt != xopts + xopts_nr; xopt++)
 327                 parse_merge_opt(&o, *xopt);
 328
 329         clean = merge_trees(&o,
 330                             head_tree,
 331                             next_tree, base_tree, &result);
 332
 333         if (active_cache_changed &&
 334             (write_cache(index_fd, active_cache, active_nr) ||
 335              commit_locked_index(&index_lock)))
 336                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 337                 die(_("%s: Unable to write new index file"), me);
 338         rollback_lock_file(&index_lock);
 339
 340         if (!clean) {
 341                 int i;
 342                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 343                 for (i = 0; i < active_nr;) {
 344                         struct cache_entry *ce = active_cache[i++];
 345                         if (ce_stage(ce)) {
 346                                 strbuf_addch(msgbuf, '\t');
 347                                 strbuf_addstr(msgbuf, ce->name);
 348                                 strbuf_addch(msgbuf, '\n');
 349                                 while (i < active_nr && !strcmp(ce->name,
 350                                                 active_cache[i]->name))
 351                                         i++;
 352                         }
 353                 }
 354         }
 355
 356         return !clean;
 357 }
 358
 359 /*
 360  * If we are cherry-pick, and if the merge did not result in
 361  * hand-editing, we will hit this commit and inherit the original
 362  * author date and name.
 363  * If we are revert, or if our cherry-pick results in a hand merge,
 364  * we had better say that the current user is responsible for that.
 365  */
 366 static int run_git_commit(const char *defmsg)
 367 {
 368         /* 6 is max possible length of our args array including NULL */
 369         const char *args[6];
 370         int i = 0;
 371
 372         args[i++] = "commit";
 373         args[i++] = "-n";
 374         if (signoff)
 375                 args[i++] = "-s";
 376         if (!edit) {
 377                 args[i++] = "-F";
 378                 args[i++] = defmsg;
 379         }
 380         args[i] = NULL;
 381
 382         return run_command_v_opt(args, RUN_GIT_CMD);
 383 }
 384
 385 static int do_pick_commit(void)
 386 {
 387         unsigned char head[20];
 388         struct commit *base, *next, *parent;
 389         const char *base_label, *next_label;
 390         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 391         char *defmsg = NULL;
 392         struct strbuf msgbuf = STRBUF_INIT;
 393         int res;
 394
 395         if (no_commit) {
 396                 /*
 397                  * We do not intend to commit immediately.  We just want to
 398                  * merge the differences in, so let's compute the tree
 399                  * that represents the "current" state for merge-recursive
 400                  * to work on.
 401                  */
 402                 if (write_cache_as_tree(head, 0, NULL))
 403                         die (_("Your index file is unmerged."));
 404         } else {
 405                 if (get_sha1("HEAD", head))
 406                         die (_("You do not have a valid HEAD"));
 407                 if (index_differs_from("HEAD", 0))
 408                         die_dirty_index(me);
 409         }
 410         discard_cache();
 411
 412         if (!commit->parents) {
 413                 parent = NULL;
 414         }
 415         else if (commit->parents->next) {
 416                 /* Reverting or cherry-picking a merge commit */
 417                 int cnt;
 418                 struct commit_list *p;
 419
 420                 if (!mainline)
 421                         die(_("Commit %s is a merge but no -m option was given."),
 422                             sha1_to_hex(commit->object.sha1));
 423
 424                 for (cnt = 1, p = commit->parents;
 425                      cnt != mainline && p;
 426                      cnt++)
 427                         p = p->next;
 428                 if (cnt != mainline || !p)
 429                         die(_("Commit %s does not have parent %d"),
 430                             sha1_to_hex(commit->object.sha1), mainline);
 431                 parent = p->item;
 432         } else if (0 < mainline)
 433                 die(_("Mainline was specified but commit %s is not a merge."),
 434                     sha1_to_hex(commit->object.sha1));
 435         else
 436                 parent = commit->parents->item;
 437
 438         if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
 439                 return fast_forward_to(commit->object.sha1, head);
 440
 441         if (parent && parse_commit(parent) < 0)
 442                 /* TRANSLATORS: The first %s will be "revert" or
 443                    "cherry-pick", the second %s a SHA1 */
 444                 die(_("%s: cannot parse parent commit %s"),
 445                     me, sha1_to_hex(parent->object.sha1));
 446
 447         if (get_message(commit->buffer, &msg) != 0)
 448                 die(_("Cannot get commit message for %s"),
 449                                 sha1_to_hex(commit->object.sha1));
 450
 451         /*
 452          * "commit" is an existing commit.  We would want to apply
 453          * the difference it introduces since its first parent "prev"
 454          * on top of the current HEAD if we are cherry-pick.  Or the
 455          * reverse of it if we are revert.
 456          */
 457
 458         defmsg = git_pathdup("MERGE_MSG");
 459
 460         if (action == REVERT) {
 461                 base = commit;
 462                 base_label = msg.label;
 463                 next = parent;
 464                 next_label = msg.parent_label;
 465                 strbuf_addstr(&msgbuf, "Revert \"");
 466                 strbuf_addstr(&msgbuf, msg.subject);
 467                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 468                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 469
 470                 if (commit->parents && commit->parents->next) {
 471                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 472                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 473                 }
 474                 strbuf_addstr(&msgbuf, ".\n");
 475         } else {
 476                 base = parent;
 477                 base_label = msg.parent_label;
 478                 next = commit;
 479                 next_label = msg.label;
 480                 add_message_to_msg(&msgbuf, msg.message);
 481                 if (no_replay) {
 482                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 483                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 484                         strbuf_addstr(&msgbuf, ")\n");
 485                 }
 486         }
 487
 488         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 489                 res = do_recursive_merge(base, next, base_label, next_label,
 490                                          head, &msgbuf);
 491                 write_message(&msgbuf, defmsg);
 492         } else {
 493                 struct commit_list *common = NULL;
 494                 struct commit_list *remotes = NULL;
 495
 496                 write_message(&msgbuf, defmsg);
 497
 498                 commit_list_insert(base, &common);
 499                 commit_list_insert(next, &remotes);
 500                 res = try_merge_command(strategy, xopts_nr, xopts, common,
 501                                         sha1_to_hex(head), remotes);
 502                 free_commit_list(common);
 503                 free_commit_list(remotes);
 504         }
 505
 506         /*
 507          * If the merge was clean or if it failed due to conflict, we write
 508          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 509          * However, if the merge did not even start, then we don't want to
 510          * write it at all.
 511          */
 512         if (action == CHERRY_PICK && !no_commit && (res == 0 || res == 1))
 513                 write_cherry_pick_head();
 514
 515         if (res) {
 516                 error(action == REVERT
 517                       ? _("could not revert %s... %s")
 518                       : _("could not apply %s... %s"),
 519                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 520                       msg.subject);
 521                 print_advice(res == 1);
 522                 rerere(allow_rerere_auto);
 523         } else {
 524                 if (!no_commit)
 525                         res = run_git_commit(defmsg);
 526         }
 527
 528         free_message(&msg);
 529         free(defmsg);
 530
 531         return res;
 532 }
 533
 534 static void prepare_revs(struct rev_info *revs)
 535 {
 536         int argc;
 537
 538         init_revisions(revs, NULL);
 539         revs->no_walk = 1;
 540         if (action != REVERT)
 541                 revs->reverse = 1;
 542
 543         argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
 544         if (argc > 1)
 545                 usage(*revert_or_cherry_pick_usage());
 546
 547         if (prepare_revision_walk(revs))
 548                 die(_("revision walk setup failed"));
 549
 550         if (!revs->commits)
 551                 die(_("empty commit set passed"));
 552 }
 553
 554 static void read_and_refresh_cache(const char *me)
 555 {
 556         static struct lock_file index_lock;
 557         int index_fd = hold_locked_index(&index_lock, 0);
 558         if (read_index_preload(&the_index, NULL) < 0)
 559                 die(_("git %s: failed to read the index"), me);
 560         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 561         if (the_index.cache_changed) {
 562                 if (write_index(&the_index, index_fd) ||
 563                     commit_locked_index(&index_lock))
 564                         die(_("git %s: failed to refresh the index"), me);
 565         }
 566         rollback_lock_file(&index_lock);
 567 }
 568
 569 static int revert_or_cherry_pick(int argc, const char **argv)
 570 {
 571         struct rev_info revs;
 572
 573         git_config(git_default_config, NULL);
 574         me = action == REVERT ? "revert" : "cherry-pick";
 575         setenv(GIT_REFLOG_ACTION, me, 0);
 576         parse_args(argc, argv);
 577
 578         if (allow_ff) {
 579                 if (signoff)
 580                         die(_("cherry-pick --ff cannot be used with --signoff"));
 581                 if (no_commit)
 582                         die(_("cherry-pick --ff cannot be used with --no-commit"));
 583                 if (no_replay)
 584                         die(_("cherry-pick --ff cannot be used with -x"));
 585                 if (edit)
 586                         die(_("cherry-pick --ff cannot be used with --edit"));
 587         }
 588
 589         read_and_refresh_cache(me);
 590
 591         prepare_revs(&revs);
 592
 593         while ((commit = get_revision(&revs))) {
 594                 int res = do_pick_commit();
 595                 if (res)
 596                         return res;
 597         }
 598
 599         return 0;
 600 }
 601
 602 int cmd_revert(int argc, const char **argv, const char *prefix)
 603 {
 604         if (isatty(0))
 605                 edit = 1;
 606         action = REVERT;
 607         return revert_or_cherry_pick(argc, argv);
 608 }
 609
 610 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 611 {
 612         action = CHERRY_PICK;
 613         return revert_or_cherry_pick(argc, argv);
 614 }