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