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(void)
 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         advise("after resolving the conflicts, mark the corrected paths");
 242         advise("with 'git add <paths>' or 'git rm <paths>'");
 243         advise("and commit the result with 'git commit'");
 244 }
 245
 246 static void write_message(struct strbuf *msgbuf, const char *filename)
 247 {
 248         static struct lock_file msg_file;
 249
 250         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 251                                                LOCK_DIE_ON_ERROR);
 252         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 253                 die_errno(_("Could not write to %s."), filename);
 254         strbuf_release(msgbuf);
 255         if (commit_lock_file(&msg_file) < 0)
 256                 die(_("Error wrapping up %s"), filename);
 257 }
 258
 259 static struct tree *empty_tree(void)
 260 {
 261         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 262 }
 263
 264 static NORETURN void die_dirty_index(const char *me)
 265 {
 266         if (read_cache_unmerged()) {
 267                 die_resolve_conflict(me);
 268         } else {
 269                 if (advice_commit_before_merge) {
 270                         if (action == REVERT)
 271                                 die(_("Your local changes would be overwritten by revert.\n"
 272                                           "Please, commit your changes or stash them to proceed."));
 273                         else
 274                                 die(_("Your local changes would be overwritten by cherry-pick.\n"
 275                                           "Please, commit your changes or stash them to proceed."));
 276                 } else {
 277                         if (action == REVERT)
 278                                 die(_("Your local changes would be overwritten by revert.\n"));
 279                         else
 280                                 die(_("Your local changes would be overwritten by cherry-pick.\n"));
 281                 }
 282         }
 283 }
 284
 285 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 286 {
 287         struct ref_lock *ref_lock;
 288
 289         read_cache();
 290         if (checkout_fast_forward(from, to))
 291                 exit(1); /* the callee should have complained already */
 292         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 293         return write_ref_sha1(ref_lock, to, "cherry-pick");
 294 }
 295
 296 static int do_recursive_merge(struct commit *base, struct commit *next,
 297                               const char *base_label, const char *next_label,
 298                               unsigned char *head, struct strbuf *msgbuf)
 299 {
 300         struct merge_options o;
 301         struct tree *result, *next_tree, *base_tree, *head_tree;
 302         int clean, index_fd;
 303         const char **xopt;
 304         static struct lock_file index_lock;
 305
 306         index_fd = hold_locked_index(&index_lock, 1);
 307
 308         read_cache();
 309
 310         init_merge_options(&o);
 311         o.ancestor = base ? base_label : "(empty tree)";
 312         o.branch1 = "HEAD";
 313         o.branch2 = next ? next_label : "(empty tree)";
 314
 315         head_tree = parse_tree_indirect(head);
 316         next_tree = next ? next->tree : empty_tree();
 317         base_tree = base ? base->tree : empty_tree();
 318
 319         for (xopt = xopts; xopt != xopts + xopts_nr; xopt++)
 320                 parse_merge_opt(&o, *xopt);
 321
 322         clean = merge_trees(&o,
 323                             head_tree,
 324                             next_tree, base_tree, &result);
 325
 326         if (active_cache_changed &&
 327             (write_cache(index_fd, active_cache, active_nr) ||
 328              commit_locked_index(&index_lock)))
 329                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 330                 die(_("%s: Unable to write new index file"), me);
 331         rollback_lock_file(&index_lock);
 332
 333         if (!clean) {
 334                 int i;
 335                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 336                 for (i = 0; i < active_nr;) {
 337                         struct cache_entry *ce = active_cache[i++];
 338                         if (ce_stage(ce)) {
 339                                 strbuf_addch(msgbuf, '\t');
 340                                 strbuf_addstr(msgbuf, ce->name);
 341                                 strbuf_addch(msgbuf, '\n');
 342                                 while (i < active_nr && !strcmp(ce->name,
 343                                                 active_cache[i]->name))
 344                                         i++;
 345                         }
 346                 }
 347         }
 348
 349         return !clean;
 350 }
 351
 352 /*
 353  * If we are cherry-pick, and if the merge did not result in
 354  * hand-editing, we will hit this commit and inherit the original
 355  * author date and name.
 356  * If we are revert, or if our cherry-pick results in a hand merge,
 357  * we had better say that the current user is responsible for that.
 358  */
 359 static int run_git_commit(const char *defmsg)
 360 {
 361         /* 6 is max possible length of our args array including NULL */
 362         const char *args[6];
 363         int i = 0;
 364
 365         args[i++] = "commit";
 366         args[i++] = "-n";
 367         if (signoff)
 368                 args[i++] = "-s";
 369         if (!edit) {
 370                 args[i++] = "-F";
 371                 args[i++] = defmsg;
 372         }
 373         args[i] = NULL;
 374
 375         return run_command_v_opt(args, RUN_GIT_CMD);
 376 }
 377
 378 static int do_pick_commit(void)
 379 {
 380         unsigned char head[20];
 381         struct commit *base, *next, *parent;
 382         const char *base_label, *next_label;
 383         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 384         char *defmsg = NULL;
 385         struct strbuf msgbuf = STRBUF_INIT;
 386         int res;
 387
 388         if (no_commit) {
 389                 /*
 390                  * We do not intend to commit immediately.  We just want to
 391                  * merge the differences in, so let's compute the tree
 392                  * that represents the "current" state for merge-recursive
 393                  * to work on.
 394                  */
 395                 if (write_cache_as_tree(head, 0, NULL))
 396                         die (_("Your index file is unmerged."));
 397         } else {
 398                 if (get_sha1("HEAD", head))
 399                         die (_("You do not have a valid HEAD"));
 400                 if (index_differs_from("HEAD", 0))
 401                         die_dirty_index(me);
 402         }
 403         discard_cache();
 404
 405         if (!commit->parents) {
 406                 parent = NULL;
 407         }
 408         else if (commit->parents->next) {
 409                 /* Reverting or cherry-picking a merge commit */
 410                 int cnt;
 411                 struct commit_list *p;
 412
 413                 if (!mainline)
 414                         die(_("Commit %s is a merge but no -m option was given."),
 415                             sha1_to_hex(commit->object.sha1));
 416
 417                 for (cnt = 1, p = commit->parents;
 418                      cnt != mainline && p;
 419                      cnt++)
 420                         p = p->next;
 421                 if (cnt != mainline || !p)
 422                         die(_("Commit %s does not have parent %d"),
 423                             sha1_to_hex(commit->object.sha1), mainline);
 424                 parent = p->item;
 425         } else if (0 < mainline)
 426                 die(_("Mainline was specified but commit %s is not a merge."),
 427                     sha1_to_hex(commit->object.sha1));
 428         else
 429                 parent = commit->parents->item;
 430
 431         if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
 432                 return fast_forward_to(commit->object.sha1, head);
 433
 434         if (parent && parse_commit(parent) < 0)
 435                 /* TRANSLATORS: The first %s will be "revert" or
 436                    "cherry-pick", the second %s a SHA1 */
 437                 die(_("%s: cannot parse parent commit %s"),
 438                     me, sha1_to_hex(parent->object.sha1));
 439
 440         if (get_message(commit->buffer, &msg) != 0)
 441                 die(_("Cannot get commit message for %s"),
 442                                 sha1_to_hex(commit->object.sha1));
 443
 444         /*
 445          * "commit" is an existing commit.  We would want to apply
 446          * the difference it introduces since its first parent "prev"
 447          * on top of the current HEAD if we are cherry-pick.  Or the
 448          * reverse of it if we are revert.
 449          */
 450
 451         defmsg = git_pathdup("MERGE_MSG");
 452
 453         if (action == REVERT) {
 454                 base = commit;
 455                 base_label = msg.label;
 456                 next = parent;
 457                 next_label = msg.parent_label;
 458                 strbuf_addstr(&msgbuf, "Revert \"");
 459                 strbuf_addstr(&msgbuf, msg.subject);
 460                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 461                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 462
 463                 if (commit->parents && commit->parents->next) {
 464                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 465                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 466                 }
 467                 strbuf_addstr(&msgbuf, ".\n");
 468         } else {
 469                 base = parent;
 470                 base_label = msg.parent_label;
 471                 next = commit;
 472                 next_label = msg.label;
 473                 add_message_to_msg(&msgbuf, msg.message);
 474                 if (no_replay) {
 475                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 476                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 477                         strbuf_addstr(&msgbuf, ")\n");
 478                 }
 479                 if (!no_commit)
 480                         write_cherry_pick_head();
 481         }
 482
 483         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 484                 res = do_recursive_merge(base, next, base_label, next_label,
 485                                          head, &msgbuf);
 486                 write_message(&msgbuf, defmsg);
 487         } else {
 488                 struct commit_list *common = NULL;
 489                 struct commit_list *remotes = NULL;
 490
 491                 write_message(&msgbuf, defmsg);
 492
 493                 commit_list_insert(base, &common);
 494                 commit_list_insert(next, &remotes);
 495                 res = try_merge_command(strategy, xopts_nr, xopts, common,
 496                                         sha1_to_hex(head), remotes);
 497                 free_commit_list(common);
 498                 free_commit_list(remotes);
 499         }
 500
 501         if (res) {
 502                 error(action == REVERT
 503                       ? _("could not revert %s... %s")
 504                       : _("could not apply %s... %s"),
 505                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 506                       msg.subject);
 507                 print_advice();
 508                 rerere(allow_rerere_auto);
 509         } else {
 510                 if (!no_commit)
 511                         res = run_git_commit(defmsg);
 512         }
 513
 514         free_message(&msg);
 515         free(defmsg);
 516
 517         return res;
 518 }
 519
 520 static void prepare_revs(struct rev_info *revs)
 521 {
 522         int argc;
 523
 524         init_revisions(revs, NULL);
 525         revs->no_walk = 1;
 526         if (action != REVERT)
 527                 revs->reverse = 1;
 528
 529         argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
 530         if (argc > 1)
 531                 usage(*revert_or_cherry_pick_usage());
 532
 533         if (prepare_revision_walk(revs))
 534                 die(_("revision walk setup failed"));
 535
 536         if (!revs->commits)
 537                 die(_("empty commit set passed"));
 538 }
 539
 540 static void read_and_refresh_cache(const char *me)
 541 {
 542         static struct lock_file index_lock;
 543         int index_fd = hold_locked_index(&index_lock, 0);
 544         if (read_index_preload(&the_index, NULL) < 0)
 545                 die(_("git %s: failed to read the index"), me);
 546         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 547         if (the_index.cache_changed) {
 548                 if (write_index(&the_index, index_fd) ||
 549                     commit_locked_index(&index_lock))
 550                         die(_("git %s: failed to refresh the index"), me);
 551         }
 552         rollback_lock_file(&index_lock);
 553 }
 554
 555 static int revert_or_cherry_pick(int argc, const char **argv)
 556 {
 557         struct rev_info revs;
 558
 559         git_config(git_default_config, NULL);
 560         me = action == REVERT ? "revert" : "cherry-pick";
 561         setenv(GIT_REFLOG_ACTION, me, 0);
 562         parse_args(argc, argv);
 563
 564         if (allow_ff) {
 565                 if (signoff)
 566                         die(_("cherry-pick --ff cannot be used with --signoff"));
 567                 if (no_commit)
 568                         die(_("cherry-pick --ff cannot be used with --no-commit"));
 569                 if (no_replay)
 570                         die(_("cherry-pick --ff cannot be used with -x"));
 571                 if (edit)
 572                         die(_("cherry-pick --ff cannot be used with --edit"));
 573         }
 574
 575         read_and_refresh_cache(me);
 576
 577         prepare_revs(&revs);
 578
 579         while ((commit = get_revision(&revs))) {
 580                 int res = do_pick_commit();
 581                 if (res)
 582                         return res;
 583         }
 584
 585         return 0;
 586 }
 587
 588 int cmd_revert(int argc, const char **argv, const char *prefix)
 589 {
 590         if (isatty(0))
 591                 edit = 1;
 592         action = REVERT;
 593         return revert_or_cherry_pick(argc, argv);
 594 }
 595
 596 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 597 {
 598         action = CHERRY_PICK;
 599         return revert_or_cherry_pick(argc, argv);
 600 }