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