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                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  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, &no_replay, "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(const char *raw_message, 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 (!raw_message)
 126                 return -1;
 127         encoding = get_encoding(raw_message);
 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 = raw_message;
 135         if (strcmp(encoding, git_commit_encoding))
 136                 out->reencoded_message = reencode_string(raw_message,
 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         if (!p)
 170                 die ("Could not read commit message of %s",
 171                                 sha1_to_hex(commit->object.sha1));
 172         while (*p && *p != '\n') {
 173                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 174                         ; /* do nothing */
 175                 if (!prefixcmp(p, "encoding ")) {
 176                         char *result = xmalloc(eol - 8 - p);
 177                         strlcpy(result, p + 9, eol - 8 - p);
 178                         return result;
 179                 }
 180                 p = eol;
 181                 if (*p == '\n')
 182                         p++;
 183         }
 184         return NULL;
 185 }
 186
 187 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 188 {
 189         const char *p = message;
 190         while (*p && (*p != '\n' || p[1] != '\n'))
 191                 p++;
 192
 193         if (!*p)
 194                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 195
 196         p += 2;
 197         strbuf_addstr(msgbuf, p);
 198 }
 199
 200 static void write_cherry_pick_head(void)
 201 {
 202         int fd;
 203         struct strbuf buf = STRBUF_INIT;
 204
 205         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 206
 207         fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
 208         if (fd < 0)
 209                 die_errno("Could not open '%s' for writing",
 210                           git_path("CHERRY_PICK_HEAD"));
 211         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 212                 die_errno("Could not write to '%s'", git_path("CHERRY_PICK_HEAD"));
 213         strbuf_release(&buf);
 214 }
 215
 216 static void advise(const char *advice, ...)
 217 {
 218         va_list params;
 219
 220         va_start(params, advice);
 221         vreportf("hint: ", advice, params);
 222         va_end(params);
 223 }
 224
 225 static void print_advice(void)
 226 {
 227         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 228
 229         if (msg) {
 230                 fprintf(stderr, "%s\n", msg);
 231                 /*
 232                  * A conflict has occured but the porcelain
 233                  * (typically rebase --interactive) wants to take care
 234                  * of the commit itself so remove CHERRY_PICK_HEAD
 235                  */
 236                 unlink(git_path("CHERRY_PICK_HEAD"));
 237                 return;
 238         }
 239
 240         advise("after resolving the conflicts, mark the corrected paths");
 241         advise("with 'git add <paths>' or 'git rm <paths>'");
 242         advise("and commit the result with 'git commit'");
 243 }
 244
 245 static void write_message(struct strbuf *msgbuf, const char *filename)
 246 {
 247         static struct lock_file msg_file;
 248
 249         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 250                                                LOCK_DIE_ON_ERROR);
 251         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 252                 die_errno("Could not write to %s.", filename);
 253         strbuf_release(msgbuf);
 254         if (commit_lock_file(&msg_file) < 0)
 255                 die("Error wrapping up %s", filename);
 256 }
 257
 258 static struct tree *empty_tree(void)
 259 {
 260         struct tree *tree = xcalloc(1, sizeof(struct tree));
 261
 262         tree->object.parsed = 1;
 263         tree->object.type = OBJ_TREE;
 264         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 265         return tree;
 266 }
 267
 268 static NORETURN void die_dirty_index(const char *me)
 269 {
 270         if (read_cache_unmerged()) {
 271                 die_resolve_conflict(me);
 272         } else {
 273                 if (advice_commit_before_merge)
 274                         die("Your local changes would be overwritten by %s.\n"
 275                             "Please, commit your changes or stash them to proceed.", me);
 276                 else
 277                         die("Your local changes would be overwritten by %s.\n", me);
 278         }
 279 }
 280
 281 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 282 {
 283         struct ref_lock *ref_lock;
 284
 285         read_cache();
 286         if (checkout_fast_forward(from, to))
 287                 exit(1); /* the callee should have complained already */
 288         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 289         return write_ref_sha1(ref_lock, to, "cherry-pick");
 290 }
 291
 292 static int do_recursive_merge(struct commit *base, struct commit *next,
 293                               const char *base_label, const char *next_label,
 294                               unsigned char *head, struct strbuf *msgbuf)
 295 {
 296         struct merge_options o;
 297         struct tree *result, *next_tree, *base_tree, *head_tree;
 298         int clean, index_fd;
 299         const char **xopt;
 300         static struct lock_file index_lock;
 301
 302         index_fd = hold_locked_index(&index_lock, 1);
 303
 304         read_cache();
 305
 306         init_merge_options(&o);
 307         o.ancestor = base ? base_label : "(empty tree)";
 308         o.branch1 = "HEAD";
 309         o.branch2 = next ? next_label : "(empty tree)";
 310
 311         head_tree = parse_tree_indirect(head);
 312         next_tree = next ? next->tree : empty_tree();
 313         base_tree = base ? base->tree : empty_tree();
 314
 315         for (xopt = xopts; xopt != xopts + xopts_nr; xopt++)
 316                 parse_merge_opt(&o, *xopt);
 317
 318         clean = merge_trees(&o,
 319                             head_tree,
 320                             next_tree, base_tree, &result);
 321
 322         if (active_cache_changed &&
 323             (write_cache(index_fd, active_cache, active_nr) ||
 324              commit_locked_index(&index_lock)))
 325                 die("%s: Unable to write new index file", me);
 326         rollback_lock_file(&index_lock);
 327
 328         if (!clean) {
 329                 int i;
 330                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 331                 for (i = 0; i < active_nr;) {
 332                         struct cache_entry *ce = active_cache[i++];
 333                         if (ce_stage(ce)) {
 334                                 strbuf_addch(msgbuf, '\t');
 335                                 strbuf_addstr(msgbuf, ce->name);
 336                                 strbuf_addch(msgbuf, '\n');
 337                                 while (i < active_nr && !strcmp(ce->name,
 338                                                 active_cache[i]->name))
 339                                         i++;
 340                         }
 341                 }
 342         }
 343
 344         return !clean;
 345 }
 346
 347 /*
 348  * If we are cherry-pick, and if the merge did not result in
 349  * hand-editing, we will hit this commit and inherit the original
 350  * author date and name.
 351  * If we are revert, or if our cherry-pick results in a hand merge,
 352  * we had better say that the current user is responsible for that.
 353  */
 354 static int run_git_commit(const char *defmsg)
 355 {
 356         /* 6 is max possible length of our args array including NULL */
 357         const char *args[6];
 358         int i = 0;
 359
 360         args[i++] = "commit";
 361         args[i++] = "-n";
 362         if (signoff)
 363                 args[i++] = "-s";
 364         if (!edit) {
 365                 args[i++] = "-F";
 366                 args[i++] = defmsg;
 367         }
 368         args[i] = NULL;
 369
 370         return run_command_v_opt(args, RUN_GIT_CMD);
 371 }
 372
 373 static int do_pick_commit(void)
 374 {
 375         unsigned char head[20];
 376         struct commit *base, *next, *parent;
 377         const char *base_label, *next_label;
 378         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 379         char *defmsg = NULL;
 380         struct strbuf msgbuf = STRBUF_INIT;
 381         int res;
 382
 383         if (no_commit) {
 384                 /*
 385                  * We do not intend to commit immediately.  We just want to
 386                  * merge the differences in, so let's compute the tree
 387                  * that represents the "current" state for merge-recursive
 388                  * to work on.
 389                  */
 390                 if (write_cache_as_tree(head, 0, NULL))
 391                         die ("Your index file is unmerged.");
 392         } else {
 393                 if (get_sha1("HEAD", head))
 394                         die ("You do not have a valid HEAD");
 395                 if (index_differs_from("HEAD", 0))
 396                         die_dirty_index(me);
 397         }
 398         discard_cache();
 399
 400         if (!commit->parents) {
 401                 if (action == REVERT)
 402                         die ("Cannot revert a root commit");
 403                 parent = NULL;
 404         }
 405         else if (commit->parents->next) {
 406                 /* Reverting or cherry-picking a merge commit */
 407                 int cnt;
 408                 struct commit_list *p;
 409
 410                 if (!mainline)
 411                         die("Commit %s is a merge but no -m option was given.",
 412                             sha1_to_hex(commit->object.sha1));
 413
 414                 for (cnt = 1, p = commit->parents;
 415                      cnt != mainline && p;
 416                      cnt++)
 417                         p = p->next;
 418                 if (cnt != mainline || !p)
 419                         die("Commit %s does not have parent %d",
 420                             sha1_to_hex(commit->object.sha1), mainline);
 421                 parent = p->item;
 422         } else if (0 < mainline)
 423                 die("Mainline was specified but commit %s is not a merge.",
 424                     sha1_to_hex(commit->object.sha1));
 425         else
 426                 parent = commit->parents->item;
 427
 428         if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
 429                 return fast_forward_to(commit->object.sha1, head);
 430
 431         if (parent && parse_commit(parent) < 0)
 432                 die("%s: cannot parse parent commit %s",
 433                     me, sha1_to_hex(parent->object.sha1));
 434
 435         if (get_message(commit->buffer, &msg) != 0)
 436                 die("Cannot get commit message for %s",
 437                                 sha1_to_hex(commit->object.sha1));
 438
 439         /*
 440          * "commit" is an existing commit.  We would want to apply
 441          * the difference it introduces since its first parent "prev"
 442          * on top of the current HEAD if we are cherry-pick.  Or the
 443          * reverse of it if we are revert.
 444          */
 445
 446         defmsg = git_pathdup("MERGE_MSG");
 447
 448         if (action == REVERT) {
 449                 base = commit;
 450                 base_label = msg.label;
 451                 next = parent;
 452                 next_label = msg.parent_label;
 453                 strbuf_addstr(&msgbuf, "Revert \"");
 454                 strbuf_addstr(&msgbuf, msg.subject);
 455                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 456                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 457
 458                 if (commit->parents->next) {
 459                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 460                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 461                 }
 462                 strbuf_addstr(&msgbuf, ".\n");
 463         } else {
 464                 base = parent;
 465                 base_label = msg.parent_label;
 466                 next = commit;
 467                 next_label = msg.label;
 468                 add_message_to_msg(&msgbuf, msg.message);
 469                 if (no_replay) {
 470                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 471                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 472                         strbuf_addstr(&msgbuf, ")\n");
 473                 }
 474                 if (!no_commit)
 475                         write_cherry_pick_head();
 476         }
 477
 478         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 479                 res = do_recursive_merge(base, next, base_label, next_label,
 480                                          head, &msgbuf);
 481                 write_message(&msgbuf, defmsg);
 482         } else {
 483                 struct commit_list *common = NULL;
 484                 struct commit_list *remotes = NULL;
 485
 486                 write_message(&msgbuf, defmsg);
 487
 488                 commit_list_insert(base, &common);
 489                 commit_list_insert(next, &remotes);
 490                 res = try_merge_command(strategy, xopts_nr, xopts, common,
 491                                         sha1_to_hex(head), remotes);
 492                 free_commit_list(common);
 493                 free_commit_list(remotes);
 494         }
 495
 496         if (res) {
 497                 error("could not %s %s... %s",
 498                       action == REVERT ? "revert" : "apply",
 499                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 500                       msg.subject);
 501                 print_advice();
 502                 rerere(allow_rerere_auto);
 503         } else {
 504                 if (!no_commit)
 505                         res = run_git_commit(defmsg);
 506         }
 507
 508         free_message(&msg);
 509         free(defmsg);
 510
 511         return res;
 512 }
 513
 514 static void prepare_revs(struct rev_info *revs)
 515 {
 516         int argc;
 517
 518         init_revisions(revs, NULL);
 519         revs->no_walk = 1;
 520         if (action != REVERT)
 521                 revs->reverse = 1;
 522
 523         argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
 524         if (argc > 1)
 525                 usage(*revert_or_cherry_pick_usage());
 526
 527         if (prepare_revision_walk(revs))
 528                 die("revision walk setup failed");
 529
 530         if (!revs->commits)
 531                 die("empty commit set passed");
 532 }
 533
 534 static void read_and_refresh_cache(const char *me)
 535 {
 536         static struct lock_file index_lock;
 537         int index_fd = hold_locked_index(&index_lock, 0);
 538         if (read_index_preload(&the_index, NULL) < 0)
 539                 die("git %s: failed to read the index", me);
 540         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 541         if (the_index.cache_changed) {
 542                 if (write_index(&the_index, index_fd) ||
 543                     commit_locked_index(&index_lock))
 544                         die("git %s: failed to refresh the index", me);
 545         }
 546         rollback_lock_file(&index_lock);
 547 }
 548
 549 static int revert_or_cherry_pick(int argc, const char **argv)
 550 {
 551         struct rev_info revs;
 552
 553         git_config(git_default_config, NULL);
 554         me = action == REVERT ? "revert" : "cherry-pick";
 555         setenv(GIT_REFLOG_ACTION, me, 0);
 556         parse_args(argc, argv);
 557
 558         if (allow_ff) {
 559                 if (signoff)
 560                         die("cherry-pick --ff cannot be used with --signoff");
 561                 if (no_commit)
 562                         die("cherry-pick --ff cannot be used with --no-commit");
 563                 if (no_replay)
 564                         die("cherry-pick --ff cannot be used with -x");
 565                 if (edit)
 566                         die("cherry-pick --ff cannot be used with --edit");
 567         }
 568
 569         read_and_refresh_cache(me);
 570
 571         prepare_revs(&revs);
 572
 573         while ((commit = get_revision(&revs))) {
 574                 int res = do_pick_commit();
 575                 if (res)
 576                         return res;
 577         }
 578
 579         return 0;
 580 }
 581
 582 int cmd_revert(int argc, const char **argv, const char *prefix)
 583 {
 584         if (isatty(0))
 585                 edit = 1;
 586         action = REVERT;
 587         return revert_or_cherry_pick(argc, argv);
 588 }
 589
 590 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 591 {
 592         action = CHERRY_PICK;
 593         return revert_or_cherry_pick(argc, argv);
 594 }