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 "wt-status.h"
   7 #include "run-command.h"
   8 #include "exec_cmd.h"
   9 #include "utf8.h"
  10 #include "parse-options.h"
  11 #include "cache-tree.h"
  12 #include "diff.h"
  13 #include "revision.h"
  14 #include "rerere.h"
  15 #include "merge-recursive.h"
  16 #include "refs.h"
  17
  18 /*
  19  * This implements the builtins revert and cherry-pick.
  20  *
  21  * Copyright (c) 2007 Johannes E. Schindelin
  22  *
  23  * Based on git-revert.sh, which is
  24  *
  25  * Copyright (c) 2005 Linus Torvalds
  26  * Copyright (c) 2005 Junio C Hamano
  27  */
  28
  29 static const char * const revert_usage[] = {
  30         "git revert [options] <commit-ish>",
  31         NULL
  32 };
  33
  34 static const char * const cherry_pick_usage[] = {
  35         "git cherry-pick [options] <commit-ish>",
  36         NULL
  37 };
  38
  39 static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
  40 static enum { REVERT, CHERRY_PICK } action;
  41 static struct commit *commit;
  42 static const char *commit_name;
  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 void parse_args(int argc, const char **argv)
  53 {
  54         const char * const * usage_str =
  55                 action == REVERT ?  revert_usage : cherry_pick_usage;
  56         unsigned char sha1[20];
  57         int noop;
  58         struct option options[] = {
  59                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  60                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  61                 OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
  62                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  63                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  64                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  65                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  66                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
  67                 OPT_END(),
  68                 OPT_END(),
  69                 OPT_END(),
  70         };
  71
  72         if (action == CHERRY_PICK) {
  73                 struct option cp_extra[] = {
  74                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
  75                         OPT_END(),
  76                 };
  77                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
  78                         die("program error");
  79         }
  80
  81         if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
  82                 usage_with_options(usage_str, options);
  83
  84         commit_name = argv[0];
  85         if (get_sha1(commit_name, sha1))
  86                 die ("Cannot find '%s'", commit_name);
  87         commit = lookup_commit_reference(sha1);
  88         if (!commit)
  89                 exit(1);
  90 }
  91
  92 struct commit_message {
  93         char *parent_label;
  94         const char *label;
  95         const char *subject;
  96         char *reencoded_message;
  97         const char *message;
  98 };
  99
 100 static int get_message(const char *raw_message, struct commit_message *out)
 101 {
 102         const char *encoding;
 103         const char *p, *abbrev, *eol;
 104         char *q;
 105         int abbrev_len, oneline_len;
 106
 107         if (!raw_message)
 108                 return -1;
 109         encoding = get_encoding(raw_message);
 110         if (!encoding)
 111                 encoding = "UTF-8";
 112         if (!git_commit_encoding)
 113                 git_commit_encoding = "UTF-8";
 114
 115         out->reencoded_message = NULL;
 116         out->message = raw_message;
 117         if (strcmp(encoding, git_commit_encoding))
 118                 out->reencoded_message = reencode_string(raw_message,
 119                                         git_commit_encoding, encoding);
 120         if (out->reencoded_message)
 121                 out->message = out->reencoded_message;
 122
 123         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 124         abbrev_len = strlen(abbrev);
 125
 126         /* Find beginning and end of commit subject. */
 127         p = out->message;
 128         while (*p && (*p != '\n' || p[1] != '\n'))
 129                 p++;
 130         if (*p) {
 131                 p += 2;
 132                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 133                         ; /* do nothing */
 134         } else
 135                 eol = p;
 136         oneline_len = eol - p;
 137
 138         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 139                               strlen("... ") + oneline_len + 1);
 140         q = out->parent_label;
 141         q = mempcpy(q, "parent of ", strlen("parent of "));
 142         out->label = q;
 143         q = mempcpy(q, abbrev, abbrev_len);
 144         q = mempcpy(q, "... ", strlen("... "));
 145         out->subject = q;
 146         q = mempcpy(q, p, oneline_len);
 147         *q = '\0';
 148         return 0;
 149 }
 150
 151 static void free_message(struct commit_message *msg)
 152 {
 153         free(msg->parent_label);
 154         free(msg->reencoded_message);
 155 }
 156
 157 static char *get_encoding(const char *message)
 158 {
 159         const char *p = message, *eol;
 160
 161         if (!p)
 162                 die ("Could not read commit message of %s",
 163                                 sha1_to_hex(commit->object.sha1));
 164         while (*p && *p != '\n') {
 165                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 166                         ; /* do nothing */
 167                 if (!prefixcmp(p, "encoding ")) {
 168                         char *result = xmalloc(eol - 8 - p);
 169                         strlcpy(result, p + 9, eol - 8 - p);
 170                         return result;
 171                 }
 172                 p = eol;
 173                 if (*p == '\n')
 174                         p++;
 175         }
 176         return NULL;
 177 }
 178
 179 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 180 {
 181         const char *p = message;
 182         while (*p && (*p != '\n' || p[1] != '\n'))
 183                 p++;
 184
 185         if (!*p)
 186                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 187
 188         p += 2;
 189         strbuf_addstr(msgbuf, p);
 190 }
 191
 192 static void set_author_ident_env(const char *message)
 193 {
 194         const char *p = message;
 195         if (!p)
 196                 die ("Could not read commit message of %s",
 197                                 sha1_to_hex(commit->object.sha1));
 198         while (*p && *p != '\n') {
 199                 const char *eol;
 200
 201                 for (eol = p; *eol && *eol != '\n'; eol++)
 202                         ; /* do nothing */
 203                 if (!prefixcmp(p, "author ")) {
 204                         char *line, *pend, *email, *timestamp;
 205
 206                         p += 7;
 207                         line = xmemdupz(p, eol - p);
 208                         email = strchr(line, '<');
 209                         if (!email)
 210                                 die ("Could not extract author email from %s",
 211                                         sha1_to_hex(commit->object.sha1));
 212                         if (email == line)
 213                                 pend = line;
 214                         else
 215                                 for (pend = email; pend != line + 1 &&
 216                                                 isspace(pend[-1]); pend--);
 217                                         ; /* do nothing */
 218                         *pend = '\0';
 219                         email++;
 220                         timestamp = strchr(email, '>');
 221                         if (!timestamp)
 222                                 die ("Could not extract author time from %s",
 223                                         sha1_to_hex(commit->object.sha1));
 224                         *timestamp = '\0';
 225                         for (timestamp++; *timestamp && isspace(*timestamp);
 226                                         timestamp++)
 227                                 ; /* do nothing */
 228                         setenv("GIT_AUTHOR_NAME", line, 1);
 229                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 230                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 231                         free(line);
 232                         return;
 233                 }
 234                 p = eol;
 235                 if (*p == '\n')
 236                         p++;
 237         }
 238         die ("No author information found in %s",
 239                         sha1_to_hex(commit->object.sha1));
 240 }
 241
 242 static char *help_msg(const char *name)
 243 {
 244         struct strbuf helpbuf = STRBUF_INIT;
 245         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 246
 247         if (msg)
 248                 return msg;
 249
 250         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 251                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 252                 "and commit the result");
 253
 254         if (action == CHERRY_PICK) {
 255                 strbuf_addf(&helpbuf, " with: \n"
 256                         "\n"
 257                         "        git commit -c %s\n",
 258                         name);
 259         }
 260         else
 261                 strbuf_addch(&helpbuf, '.');
 262         return strbuf_detach(&helpbuf, NULL);
 263 }
 264
 265 static void write_message(struct strbuf *msgbuf, const char *filename)
 266 {
 267         static struct lock_file msg_file;
 268
 269         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 270                                                LOCK_DIE_ON_ERROR);
 271         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 272                 die_errno("Could not write to %s.", filename);
 273         strbuf_release(msgbuf);
 274         if (commit_lock_file(&msg_file) < 0)
 275                 die("Error wrapping up %s", filename);
 276 }
 277
 278 static struct tree *empty_tree(void)
 279 {
 280         struct tree *tree = xcalloc(1, sizeof(struct tree));
 281
 282         tree->object.parsed = 1;
 283         tree->object.type = OBJ_TREE;
 284         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 285         return tree;
 286 }
 287
 288 static NORETURN void die_dirty_index(const char *me)
 289 {
 290         if (read_cache_unmerged()) {
 291                 die_resolve_conflict(me);
 292         } else {
 293                 if (advice_commit_before_merge)
 294                         die("Your local changes would be overwritten by %s.\n"
 295                             "Please, commit your changes or stash them to proceed.", me);
 296                 else
 297                         die("Your local changes would be overwritten by %s.\n", me);
 298         }
 299 }
 300
 301 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 302 {
 303         struct ref_lock *ref_lock;
 304
 305         read_cache();
 306         if (checkout_fast_forward(from, to))
 307                 exit(1); /* the callee should have complained already */
 308         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 309         return write_ref_sha1(ref_lock, to, "cherry-pick");
 310 }
 311
 312 static void do_recursive_merge(struct commit *base, struct commit *next,
 313                                const char *base_label, const char *next_label,
 314                                unsigned char *head, struct strbuf *msgbuf,
 315                                char *defmsg)
 316 {
 317         struct merge_options o;
 318         struct tree *result, *next_tree, *base_tree, *head_tree;
 319         int clean, index_fd;
 320         static struct lock_file index_lock;
 321
 322         index_fd = hold_locked_index(&index_lock, 1);
 323
 324         read_cache();
 325         init_merge_options(&o);
 326         o.ancestor = base ? base_label : "(empty tree)";
 327         o.branch1 = "HEAD";
 328         o.branch2 = next ? next_label : "(empty tree)";
 329
 330         head_tree = parse_tree_indirect(head);
 331         next_tree = next ? next->tree : empty_tree();
 332         base_tree = base ? base->tree : empty_tree();
 333
 334         clean = merge_trees(&o,
 335                             head_tree,
 336                             next_tree, base_tree, &result);
 337
 338         if (active_cache_changed &&
 339             (write_cache(index_fd, active_cache, active_nr) ||
 340              commit_locked_index(&index_lock)))
 341                 die("%s: Unable to write new index file", me);
 342         rollback_lock_file(&index_lock);
 343
 344         if (!clean) {
 345                 int i;
 346                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 347                 for (i = 0; i < active_nr;) {
 348                         struct cache_entry *ce = active_cache[i++];
 349                         if (ce_stage(ce)) {
 350                                 strbuf_addch(msgbuf, '\t');
 351                                 strbuf_addstr(msgbuf, ce->name);
 352                                 strbuf_addch(msgbuf, '\n');
 353                                 while (i < active_nr && !strcmp(ce->name,
 354                                                 active_cache[i]->name))
 355                                         i++;
 356                         }
 357                 }
 358                 write_message(msgbuf, defmsg);
 359                 fprintf(stderr, "Automatic %s failed.%s\n",
 360                         me, help_msg(commit_name));
 361                 rerere(allow_rerere_auto);
 362                 exit(1);
 363         }
 364         write_message(msgbuf, defmsg);
 365         fprintf(stderr, "Finished one %s.\n", me);
 366 }
 367
 368 static int revert_or_cherry_pick(int argc, const char **argv)
 369 {
 370         unsigned char head[20];
 371         struct commit *base, *next, *parent;
 372         const char *base_label, *next_label;
 373         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 374         char *defmsg = NULL;
 375         struct strbuf msgbuf = STRBUF_INIT;
 376
 377         git_config(git_default_config, NULL);
 378         me = action == REVERT ? "revert" : "cherry-pick";
 379         setenv(GIT_REFLOG_ACTION, me, 0);
 380         parse_args(argc, argv);
 381
 382         /* this is copied from the shell script, but it's never triggered... */
 383         if (action == REVERT && !no_replay)
 384                 die("revert is incompatible with replay");
 385
 386         if (allow_ff) {
 387                 if (signoff)
 388                         die("cherry-pick --ff cannot be used with --signoff");
 389                 if (no_commit)
 390                         die("cherry-pick --ff cannot be used with --no-commit");
 391                 if (no_replay)
 392                         die("cherry-pick --ff cannot be used with -x");
 393                 if (edit)
 394                         die("cherry-pick --ff cannot be used with --edit");
 395         }
 396
 397         if (read_cache() < 0)
 398                 die("git %s: failed to read the index", me);
 399         if (no_commit) {
 400                 /*
 401                  * We do not intend to commit immediately.  We just want to
 402                  * merge the differences in, so let's compute the tree
 403                  * that represents the "current" state for merge-recursive
 404                  * to work on.
 405                  */
 406                 if (write_cache_as_tree(head, 0, NULL))
 407                         die ("Your index file is unmerged.");
 408         } else {
 409                 if (get_sha1("HEAD", head))
 410                         die ("You do not have a valid HEAD");
 411                 if (index_differs_from("HEAD", 0))
 412                         die_dirty_index(me);
 413         }
 414         discard_cache();
 415
 416         if (!commit->parents) {
 417                 if (action == REVERT)
 418                         die ("Cannot revert a root commit");
 419                 parent = NULL;
 420         }
 421         else if (commit->parents->next) {
 422                 /* Reverting or cherry-picking a merge commit */
 423                 int cnt;
 424                 struct commit_list *p;
 425
 426                 if (!mainline)
 427                         die("Commit %s is a merge but no -m option was given.",
 428                             sha1_to_hex(commit->object.sha1));
 429
 430                 for (cnt = 1, p = commit->parents;
 431                      cnt != mainline && p;
 432                      cnt++)
 433                         p = p->next;
 434                 if (cnt != mainline || !p)
 435                         die("Commit %s does not have parent %d",
 436                             sha1_to_hex(commit->object.sha1), mainline);
 437                 parent = p->item;
 438         } else if (0 < mainline)
 439                 die("Mainline was specified but commit %s is not a merge.",
 440                     sha1_to_hex(commit->object.sha1));
 441         else
 442                 parent = commit->parents->item;
 443
 444         if (allow_ff && !hashcmp(parent->object.sha1, head))
 445                 return fast_forward_to(commit->object.sha1, head);
 446
 447         if (parent && parse_commit(parent) < 0)
 448                 die("%s: cannot parse parent commit %s",
 449                     me, sha1_to_hex(parent->object.sha1));
 450
 451         if (get_message(commit->buffer, &msg) != 0)
 452                 die("Cannot get commit message for %s",
 453                                 sha1_to_hex(commit->object.sha1));
 454
 455         /*
 456          * "commit" is an existing commit.  We would want to apply
 457          * the difference it introduces since its first parent "prev"
 458          * on top of the current HEAD if we are cherry-pick.  Or the
 459          * reverse of it if we are revert.
 460          */
 461
 462         defmsg = git_pathdup("MERGE_MSG");
 463
 464         if (action == REVERT) {
 465                 base = commit;
 466                 base_label = msg.label;
 467                 next = parent;
 468                 next_label = msg.parent_label;
 469                 strbuf_addstr(&msgbuf, "Revert \"");
 470                 strbuf_addstr(&msgbuf, msg.subject);
 471                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 472                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 473
 474                 if (commit->parents->next) {
 475                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 476                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 477                 }
 478                 strbuf_addstr(&msgbuf, ".\n");
 479         } else {
 480                 base = parent;
 481                 base_label = msg.parent_label;
 482                 next = commit;
 483                 next_label = msg.label;
 484                 set_author_ident_env(msg.message);
 485                 add_message_to_msg(&msgbuf, msg.message);
 486                 if (no_replay) {
 487                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 488                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 489                         strbuf_addstr(&msgbuf, ")\n");
 490                 }
 491         }
 492
 493         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT)
 494                 do_recursive_merge(base, next, base_label, next_label,
 495                                    head, &msgbuf, defmsg);
 496         else {
 497                 int res;
 498                 struct commit_list *common = NULL;
 499                 struct commit_list *remotes = NULL;
 500                 write_message(&msgbuf, defmsg);
 501                 commit_list_insert(base, &common);
 502                 commit_list_insert(next, &remotes);
 503                 res = try_merge_command(strategy, common,
 504                                         sha1_to_hex(head), remotes);
 505                 free_commit_list(common);
 506                 free_commit_list(remotes);
 507                 if (res) {
 508                         fprintf(stderr, "Automatic %s with strategy %s failed.%s\n",
 509                                 me, strategy, help_msg(commit_name));
 510                         rerere(allow_rerere_auto);
 511                         exit(1);
 512                 }
 513         }
 514
 515         /*
 516          *
 517          * If we are cherry-pick, and if the merge did not result in
 518          * hand-editing, we will hit this commit and inherit the original
 519          * author date and name.
 520          * If we are revert, or if our cherry-pick results in a hand merge,
 521          * we had better say that the current user is responsible for that.
 522          */
 523
 524         if (!no_commit) {
 525                 /* 6 is max possible length of our args array including NULL */
 526                 const char *args[6];
 527                 int i = 0;
 528                 args[i++] = "commit";
 529                 args[i++] = "-n";
 530                 if (signoff)
 531                         args[i++] = "-s";
 532                 if (!edit) {
 533                         args[i++] = "-F";
 534                         args[i++] = defmsg;
 535                 }
 536                 args[i] = NULL;
 537                 return execv_git_cmd(args);
 538         }
 539         free_message(&msg);
 540         free(defmsg);
 541
 542         return 0;
 543 }
 544
 545 int cmd_revert(int argc, const char **argv, const char *prefix)
 546 {
 547         if (isatty(0))
 548                 edit = 1;
 549         no_replay = 1;
 550         action = REVERT;
 551         return revert_or_cherry_pick(argc, argv);
 552 }
 553
 554 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 555 {
 556         no_replay = 0;
 557         action = CHERRY_PICK;
 558         return revert_or_cherry_pick(argc, argv);
 559 }