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 int commit_argc;
  43 static const char **commit_argv;
  44 static int allow_rerere_auto;
  45
  46 static const char *me;
  47 static const char *strategy;
  48
  49 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  50
  51 static char *get_encoding(const char *message);
  52
  53 static const char * const *revert_or_cherry_pick_usage(void)
  54 {
  55         return action == REVERT ? revert_usage : cherry_pick_usage;
  56 }
  57
  58 static void parse_args(int argc, const char **argv)
  59 {
  60         const char * const * usage_str = revert_or_cherry_pick_usage();
  61         int noop;
  62         struct option options[] = {
  63                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  64                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  65                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  66                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  67                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  68                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  69                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
  70                 OPT_END(),
  71                 OPT_END(),
  72                 OPT_END(),
  73         };
  74
  75         if (action == CHERRY_PICK) {
  76                 struct option cp_extra[] = {
  77                         OPT_BOOLEAN('x', NULL, &no_replay, "append commit name"),
  78                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
  79                         OPT_END(),
  80                 };
  81                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
  82                         die("program error");
  83         }
  84
  85         commit_argc = parse_options(argc, argv, NULL, options, usage_str,
  86                                     PARSE_OPT_KEEP_ARGV0 |
  87                                     PARSE_OPT_KEEP_UNKNOWN);
  88         if (commit_argc < 2)
  89                 usage_with_options(usage_str, options);
  90
  91         commit_argv = argv;
  92 }
  93
  94 struct commit_message {
  95         char *parent_label;
  96         const char *label;
  97         const char *subject;
  98         char *reencoded_message;
  99         const char *message;
 100 };
 101
 102 static int get_message(const char *raw_message, struct commit_message *out)
 103 {
 104         const char *encoding;
 105         const char *abbrev, *subject;
 106         int abbrev_len, subject_len;
 107         char *q;
 108
 109         if (!raw_message)
 110                 return -1;
 111         encoding = get_encoding(raw_message);
 112         if (!encoding)
 113                 encoding = "UTF-8";
 114         if (!git_commit_encoding)
 115                 git_commit_encoding = "UTF-8";
 116
 117         out->reencoded_message = NULL;
 118         out->message = raw_message;
 119         if (strcmp(encoding, git_commit_encoding))
 120                 out->reencoded_message = reencode_string(raw_message,
 121                                         git_commit_encoding, encoding);
 122         if (out->reencoded_message)
 123                 out->message = out->reencoded_message;
 124
 125         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 126         abbrev_len = strlen(abbrev);
 127
 128         subject_len = find_commit_subject(out->message, &subject);
 129
 130         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 131                               strlen("... ") + subject_len + 1);
 132         q = out->parent_label;
 133         q = mempcpy(q, "parent of ", strlen("parent of "));
 134         out->label = q;
 135         q = mempcpy(q, abbrev, abbrev_len);
 136         q = mempcpy(q, "... ", strlen("... "));
 137         out->subject = q;
 138         q = mempcpy(q, subject, subject_len);
 139         *q = '\0';
 140         return 0;
 141 }
 142
 143 static void free_message(struct commit_message *msg)
 144 {
 145         free(msg->parent_label);
 146         free(msg->reencoded_message);
 147 }
 148
 149 static char *get_encoding(const char *message)
 150 {
 151         const char *p = message, *eol;
 152
 153         if (!p)
 154                 die ("Could not read commit message of %s",
 155                                 sha1_to_hex(commit->object.sha1));
 156         while (*p && *p != '\n') {
 157                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 158                         ; /* do nothing */
 159                 if (!prefixcmp(p, "encoding ")) {
 160                         char *result = xmalloc(eol - 8 - p);
 161                         strlcpy(result, p + 9, eol - 8 - p);
 162                         return result;
 163                 }
 164                 p = eol;
 165                 if (*p == '\n')
 166                         p++;
 167         }
 168         return NULL;
 169 }
 170
 171 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 172 {
 173         const char *p = message;
 174         while (*p && (*p != '\n' || p[1] != '\n'))
 175                 p++;
 176
 177         if (!*p)
 178                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 179
 180         p += 2;
 181         strbuf_addstr(msgbuf, p);
 182 }
 183
 184 static void set_author_ident_env(const char *message)
 185 {
 186         const char *p = message;
 187         if (!p)
 188                 die ("Could not read commit message of %s",
 189                                 sha1_to_hex(commit->object.sha1));
 190         while (*p && *p != '\n') {
 191                 const char *eol;
 192
 193                 for (eol = p; *eol && *eol != '\n'; eol++)
 194                         ; /* do nothing */
 195                 if (!prefixcmp(p, "author ")) {
 196                         char *line, *pend, *email, *timestamp;
 197
 198                         p += 7;
 199                         line = xmemdupz(p, eol - p);
 200                         email = strchr(line, '<');
 201                         if (!email)
 202                                 die ("Could not extract author email from %s",
 203                                         sha1_to_hex(commit->object.sha1));
 204                         if (email == line)
 205                                 pend = line;
 206                         else
 207                                 for (pend = email; pend != line + 1 &&
 208                                                 isspace(pend[-1]); pend--);
 209                                         ; /* do nothing */
 210                         *pend = '\0';
 211                         email++;
 212                         timestamp = strchr(email, '>');
 213                         if (!timestamp)
 214                                 die ("Could not extract author time from %s",
 215                                         sha1_to_hex(commit->object.sha1));
 216                         *timestamp = '\0';
 217                         for (timestamp++; *timestamp && isspace(*timestamp);
 218                                         timestamp++)
 219                                 ; /* do nothing */
 220                         setenv("GIT_AUTHOR_NAME", line, 1);
 221                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 222                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 223                         free(line);
 224                         return;
 225                 }
 226                 p = eol;
 227                 if (*p == '\n')
 228                         p++;
 229         }
 230         die ("No author information found in %s",
 231                         sha1_to_hex(commit->object.sha1));
 232 }
 233
 234 static void advise(const char *advice, ...)
 235 {
 236         va_list params;
 237
 238         va_start(params, advice);
 239         vreportf("hint: ", advice, params);
 240         va_end(params);
 241 }
 242
 243 static void print_advice(void)
 244 {
 245         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 246
 247         if (msg) {
 248                 fprintf(stderr, "%s\n", msg);
 249                 return;
 250         }
 251
 252         advise("after resolving the conflicts, mark the corrected paths");
 253         advise("with 'git add <paths>' or 'git rm <paths>'");
 254
 255         if (action == CHERRY_PICK)
 256                 advise("and commit the result with 'git commit -c %s'",
 257                        find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 258 }
 259
 260 static void write_message(struct strbuf *msgbuf, const char *filename)
 261 {
 262         static struct lock_file msg_file;
 263
 264         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 265                                                LOCK_DIE_ON_ERROR);
 266         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 267                 die_errno("Could not write to %s.", filename);
 268         strbuf_release(msgbuf);
 269         if (commit_lock_file(&msg_file) < 0)
 270                 die("Error wrapping up %s", filename);
 271 }
 272
 273 static struct tree *empty_tree(void)
 274 {
 275         struct tree *tree = xcalloc(1, sizeof(struct tree));
 276
 277         tree->object.parsed = 1;
 278         tree->object.type = OBJ_TREE;
 279         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 280         return tree;
 281 }
 282
 283 static NORETURN void die_dirty_index(const char *me)
 284 {
 285         if (read_cache_unmerged()) {
 286                 die_resolve_conflict(me);
 287         } else {
 288                 if (advice_commit_before_merge)
 289                         die("Your local changes would be overwritten by %s.\n"
 290                             "Please, commit your changes or stash them to proceed.", me);
 291                 else
 292                         die("Your local changes would be overwritten by %s.\n", me);
 293         }
 294 }
 295
 296 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 297 {
 298         struct ref_lock *ref_lock;
 299
 300         read_cache();
 301         if (checkout_fast_forward(from, to))
 302                 exit(1); /* the callee should have complained already */
 303         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 304         return write_ref_sha1(ref_lock, to, "cherry-pick");
 305 }
 306
 307 static int do_recursive_merge(struct commit *base, struct commit *next,
 308                               const char *base_label, const char *next_label,
 309                               unsigned char *head, struct strbuf *msgbuf)
 310 {
 311         struct merge_options o;
 312         struct tree *result, *next_tree, *base_tree, *head_tree;
 313         int clean, index_fd;
 314         static struct lock_file index_lock;
 315
 316         index_fd = hold_locked_index(&index_lock, 1);
 317
 318         read_cache();
 319
 320         /*
 321          * NEEDSWORK: cherry-picking between branches with
 322          * different end-of-line normalization is a pain;
 323          * plumb in an option to set o.renormalize?
 324          * (or better: arbitrary -X options)
 325          */
 326         init_merge_options(&o);
 327         o.ancestor = base ? base_label : "(empty tree)";
 328         o.branch1 = "HEAD";
 329         o.branch2 = next ? next_label : "(empty tree)";
 330
 331         head_tree = parse_tree_indirect(head);
 332         next_tree = next ? next->tree : empty_tree();
 333         base_tree = base ? base->tree : empty_tree();
 334
 335         clean = merge_trees(&o,
 336                             head_tree,
 337                             next_tree, base_tree, &result);
 338
 339         if (active_cache_changed &&
 340             (write_cache(index_fd, active_cache, active_nr) ||
 341              commit_locked_index(&index_lock)))
 342                 die("%s: Unable to write new index file", me);
 343         rollback_lock_file(&index_lock);
 344
 345         if (!clean) {
 346                 int i;
 347                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 348                 for (i = 0; i < active_nr;) {
 349                         struct cache_entry *ce = active_cache[i++];
 350                         if (ce_stage(ce)) {
 351                                 strbuf_addch(msgbuf, '\t');
 352                                 strbuf_addstr(msgbuf, ce->name);
 353                                 strbuf_addch(msgbuf, '\n');
 354                                 while (i < active_nr && !strcmp(ce->name,
 355                                                 active_cache[i]->name))
 356                                         i++;
 357                         }
 358                 }
 359         }
 360
 361         return !clean;
 362 }
 363
 364 /*
 365  * If we are cherry-pick, and if the merge did not result in
 366  * hand-editing, we will hit this commit and inherit the original
 367  * author date and name.
 368  * If we are revert, or if our cherry-pick results in a hand merge,
 369  * we had better say that the current user is responsible for that.
 370  */
 371 static int run_git_commit(const char *defmsg)
 372 {
 373         /* 6 is max possible length of our args array including NULL */
 374         const char *args[6];
 375         int i = 0;
 376
 377         args[i++] = "commit";
 378         args[i++] = "-n";
 379         if (signoff)
 380                 args[i++] = "-s";
 381         if (!edit) {
 382                 args[i++] = "-F";
 383                 args[i++] = defmsg;
 384         }
 385         args[i] = NULL;
 386
 387         return run_command_v_opt(args, RUN_GIT_CMD);
 388 }
 389
 390 static int do_pick_commit(void)
 391 {
 392         unsigned char head[20];
 393         struct commit *base, *next, *parent;
 394         const char *base_label, *next_label;
 395         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 396         char *defmsg = NULL;
 397         struct strbuf msgbuf = STRBUF_INIT;
 398         int res;
 399
 400         if (no_commit) {
 401                 /*
 402                  * We do not intend to commit immediately.  We just want to
 403                  * merge the differences in, so let's compute the tree
 404                  * that represents the "current" state for merge-recursive
 405                  * to work on.
 406                  */
 407                 if (write_cache_as_tree(head, 0, NULL))
 408                         die ("Your index file is unmerged.");
 409         } else {
 410                 if (get_sha1("HEAD", head))
 411                         die ("You do not have a valid HEAD");
 412                 if (index_differs_from("HEAD", 0))
 413                         die_dirty_index(me);
 414         }
 415         discard_cache();
 416
 417         if (!commit->parents) {
 418                 if (action == REVERT)
 419                         die ("Cannot revert a root commit");
 420                 parent = NULL;
 421         }
 422         else if (commit->parents->next) {
 423                 /* Reverting or cherry-picking a merge commit */
 424                 int cnt;
 425                 struct commit_list *p;
 426
 427                 if (!mainline)
 428                         die("Commit %s is a merge but no -m option was given.",
 429                             sha1_to_hex(commit->object.sha1));
 430
 431                 for (cnt = 1, p = commit->parents;
 432                      cnt != mainline && p;
 433                      cnt++)
 434                         p = p->next;
 435                 if (cnt != mainline || !p)
 436                         die("Commit %s does not have parent %d",
 437                             sha1_to_hex(commit->object.sha1), mainline);
 438                 parent = p->item;
 439         } else if (0 < mainline)
 440                 die("Mainline was specified but commit %s is not a merge.",
 441                     sha1_to_hex(commit->object.sha1));
 442         else
 443                 parent = commit->parents->item;
 444
 445         if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
 446                 return fast_forward_to(commit->object.sha1, head);
 447
 448         if (parent && parse_commit(parent) < 0)
 449                 die("%s: cannot parse parent commit %s",
 450                     me, sha1_to_hex(parent->object.sha1));
 451
 452         if (get_message(commit->buffer, &msg) != 0)
 453                 die("Cannot get commit message for %s",
 454                                 sha1_to_hex(commit->object.sha1));
 455
 456         /*
 457          * "commit" is an existing commit.  We would want to apply
 458          * the difference it introduces since its first parent "prev"
 459          * on top of the current HEAD if we are cherry-pick.  Or the
 460          * reverse of it if we are revert.
 461          */
 462
 463         defmsg = git_pathdup("MERGE_MSG");
 464
 465         if (action == REVERT) {
 466                 base = commit;
 467                 base_label = msg.label;
 468                 next = parent;
 469                 next_label = msg.parent_label;
 470                 strbuf_addstr(&msgbuf, "Revert \"");
 471                 strbuf_addstr(&msgbuf, msg.subject);
 472                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 473                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 474
 475                 if (commit->parents->next) {
 476                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 477                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 478                 }
 479                 strbuf_addstr(&msgbuf, ".\n");
 480         } else {
 481                 base = parent;
 482                 base_label = msg.parent_label;
 483                 next = commit;
 484                 next_label = msg.label;
 485                 set_author_ident_env(msg.message);
 486                 add_message_to_msg(&msgbuf, msg.message);
 487                 if (no_replay) {
 488                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 489                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 490                         strbuf_addstr(&msgbuf, ")\n");
 491                 }
 492         }
 493
 494         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 495                 res = do_recursive_merge(base, next, base_label, next_label,
 496                                          head, &msgbuf);
 497                 write_message(&msgbuf, defmsg);
 498         } else {
 499                 struct commit_list *common = NULL;
 500                 struct commit_list *remotes = NULL;
 501
 502                 write_message(&msgbuf, defmsg);
 503
 504                 commit_list_insert(base, &common);
 505                 commit_list_insert(next, &remotes);
 506                 res = try_merge_command(strategy, common,
 507                                         sha1_to_hex(head), remotes);
 508                 free_commit_list(common);
 509                 free_commit_list(remotes);
 510         }
 511
 512         if (res) {
 513                 error("could not %s %s... %s",
 514                       action == REVERT ? "revert" : "apply",
 515                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 516                       msg.subject);
 517                 print_advice();
 518                 rerere(allow_rerere_auto);
 519         } else {
 520                 if (!no_commit)
 521                         res = run_git_commit(defmsg);
 522         }
 523
 524         free_message(&msg);
 525         free(defmsg);
 526
 527         return res;
 528 }
 529
 530 static void prepare_revs(struct rev_info *revs)
 531 {
 532         int argc;
 533
 534         init_revisions(revs, NULL);
 535         revs->no_walk = 1;
 536         if (action != REVERT)
 537                 revs->reverse = 1;
 538
 539         argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
 540         if (argc > 1)
 541                 usage(*revert_or_cherry_pick_usage());
 542
 543         if (prepare_revision_walk(revs))
 544                 die("revision walk setup failed");
 545
 546         if (!revs->commits)
 547                 die("empty commit set passed");
 548 }
 549
 550 static void read_and_refresh_cache(const char *me)
 551 {
 552         static struct lock_file index_lock;
 553         int index_fd = hold_locked_index(&index_lock, 0);
 554         if (read_index_preload(&the_index, NULL) < 0)
 555                 die("git %s: failed to read the index", me);
 556         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 557         if (the_index.cache_changed) {
 558                 if (write_index(&the_index, index_fd) ||
 559                     commit_locked_index(&index_lock))
 560                         die("git %s: failed to refresh the index", me);
 561         }
 562         rollback_lock_file(&index_lock);
 563 }
 564
 565 static int revert_or_cherry_pick(int argc, const char **argv)
 566 {
 567         struct rev_info revs;
 568
 569         git_config(git_default_config, NULL);
 570         me = action == REVERT ? "revert" : "cherry-pick";
 571         setenv(GIT_REFLOG_ACTION, me, 0);
 572         parse_args(argc, argv);
 573
 574         if (allow_ff) {
 575                 if (signoff)
 576                         die("cherry-pick --ff cannot be used with --signoff");
 577                 if (no_commit)
 578                         die("cherry-pick --ff cannot be used with --no-commit");
 579                 if (no_replay)
 580                         die("cherry-pick --ff cannot be used with -x");
 581                 if (edit)
 582                         die("cherry-pick --ff cannot be used with --edit");
 583         }
 584
 585         read_and_refresh_cache(me);
 586
 587         prepare_revs(&revs);
 588
 589         while ((commit = get_revision(&revs))) {
 590                 int res = do_pick_commit();
 591                 if (res)
 592                         return res;
 593         }
 594
 595         return 0;
 596 }
 597
 598 int cmd_revert(int argc, const char **argv, const char *prefix)
 599 {
 600         if (isatty(0))
 601                 edit = 1;
 602         action = REVERT;
 603         return revert_or_cherry_pick(argc, argv);
 604 }
 605
 606 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 607 {
 608         action = CHERRY_PICK;
 609         return revert_or_cherry_pick(argc, argv);
 610 }