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
  48 /* Merge strategy. */
  49 static const char *strategy;
  50 static const char **xopts;
  51 static size_t xopts_nr, xopts_alloc;
  52
  53 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  54
  55 static char *get_encoding(const char *message);
  56
  57 static const char * const *revert_or_cherry_pick_usage(void)
  58 {
  59         return action == REVERT ? revert_usage : cherry_pick_usage;
  60 }
  61
  62 static int option_parse_x(const struct option *opt,
  63                           const char *arg, int unset)
  64 {
  65         if (unset)
  66                 return 0;
  67
  68         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
  69         xopts[xopts_nr++] = xstrdup(arg);
  70         return 0;
  71 }
  72
  73 static void parse_args(int argc, const char **argv)
  74 {
  75         const char * const * usage_str = revert_or_cherry_pick_usage();
  76         int noop;
  77         struct option options[] = {
  78                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  79                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  80                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  81                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  82                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  83                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  84                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
  85                 OPT_CALLBACK('X', "strategy-option", &xopts, "option",
  86                         "option for merge strategy", option_parse_x),
  87                 OPT_END(),
  88                 OPT_END(),
  89                 OPT_END(),
  90         };
  91
  92         if (action == CHERRY_PICK) {
  93                 struct option cp_extra[] = {
  94                         OPT_BOOLEAN('x', NULL, &no_replay, "append commit name"),
  95                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
  96                         OPT_END(),
  97                 };
  98                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
  99                         die("program error");
 100         }
 101
 102         commit_argc = parse_options(argc, argv, NULL, options, usage_str,
 103                                     PARSE_OPT_KEEP_ARGV0 |
 104                                     PARSE_OPT_KEEP_UNKNOWN);
 105         if (commit_argc < 2)
 106                 usage_with_options(usage_str, options);
 107
 108         commit_argv = argv;
 109 }
 110
 111 struct commit_message {
 112         char *parent_label;
 113         const char *label;
 114         const char *subject;
 115         char *reencoded_message;
 116         const char *message;
 117 };
 118
 119 static int get_message(const char *raw_message, struct commit_message *out)
 120 {
 121         const char *encoding;
 122         const char *abbrev, *subject;
 123         int abbrev_len, subject_len;
 124         char *q;
 125
 126         if (!raw_message)
 127                 return -1;
 128         encoding = get_encoding(raw_message);
 129         if (!encoding)
 130                 encoding = "UTF-8";
 131         if (!git_commit_encoding)
 132                 git_commit_encoding = "UTF-8";
 133
 134         out->reencoded_message = NULL;
 135         out->message = raw_message;
 136         if (strcmp(encoding, git_commit_encoding))
 137                 out->reencoded_message = reencode_string(raw_message,
 138                                         git_commit_encoding, encoding);
 139         if (out->reencoded_message)
 140                 out->message = out->reencoded_message;
 141
 142         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 143         abbrev_len = strlen(abbrev);
 144
 145         subject_len = find_commit_subject(out->message, &subject);
 146
 147         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 148                               strlen("... ") + subject_len + 1);
 149         q = out->parent_label;
 150         q = mempcpy(q, "parent of ", strlen("parent of "));
 151         out->label = q;
 152         q = mempcpy(q, abbrev, abbrev_len);
 153         q = mempcpy(q, "... ", strlen("... "));
 154         out->subject = q;
 155         q = mempcpy(q, subject, subject_len);
 156         *q = '\0';
 157         return 0;
 158 }
 159
 160 static void free_message(struct commit_message *msg)
 161 {
 162         free(msg->parent_label);
 163         free(msg->reencoded_message);
 164 }
 165
 166 static char *get_encoding(const char *message)
 167 {
 168         const char *p = message, *eol;
 169
 170         if (!p)
 171                 die ("Could not read commit message of %s",
 172                                 sha1_to_hex(commit->object.sha1));
 173         while (*p && *p != '\n') {
 174                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 175                         ; /* do nothing */
 176                 if (!prefixcmp(p, "encoding ")) {
 177                         char *result = xmalloc(eol - 8 - p);
 178                         strlcpy(result, p + 9, eol - 8 - p);
 179                         return result;
 180                 }
 181                 p = eol;
 182                 if (*p == '\n')
 183                         p++;
 184         }
 185         return NULL;
 186 }
 187
 188 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 189 {
 190         const char *p = message;
 191         while (*p && (*p != '\n' || p[1] != '\n'))
 192                 p++;
 193
 194         if (!*p)
 195                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 196
 197         p += 2;
 198         strbuf_addstr(msgbuf, p);
 199 }
 200
 201 static void set_author_ident_env(const char *message)
 202 {
 203         const char *p = message;
 204         if (!p)
 205                 die ("Could not read commit message of %s",
 206                                 sha1_to_hex(commit->object.sha1));
 207         while (*p && *p != '\n') {
 208                 const char *eol;
 209
 210                 for (eol = p; *eol && *eol != '\n'; eol++)
 211                         ; /* do nothing */
 212                 if (!prefixcmp(p, "author ")) {
 213                         char *line, *pend, *email, *timestamp;
 214
 215                         p += 7;
 216                         line = xmemdupz(p, eol - p);
 217                         email = strchr(line, '<');
 218                         if (!email)
 219                                 die ("Could not extract author email from %s",
 220                                         sha1_to_hex(commit->object.sha1));
 221                         if (email == line)
 222                                 pend = line;
 223                         else
 224                                 for (pend = email; pend != line + 1 &&
 225                                                 isspace(pend[-1]); pend--);
 226                                         ; /* do nothing */
 227                         *pend = '\0';
 228                         email++;
 229                         timestamp = strchr(email, '>');
 230                         if (!timestamp)
 231                                 die ("Could not extract author time from %s",
 232                                         sha1_to_hex(commit->object.sha1));
 233                         *timestamp = '\0';
 234                         for (timestamp++; *timestamp && isspace(*timestamp);
 235                                         timestamp++)
 236                                 ; /* do nothing */
 237                         setenv("GIT_AUTHOR_NAME", line, 1);
 238                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 239                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 240                         free(line);
 241                         return;
 242                 }
 243                 p = eol;
 244                 if (*p == '\n')
 245                         p++;
 246         }
 247         die ("No author information found in %s",
 248                         sha1_to_hex(commit->object.sha1));
 249 }
 250
 251 static void advise(const char *advice, ...)
 252 {
 253         va_list params;
 254
 255         va_start(params, advice);
 256         vreportf("hint: ", advice, params);
 257         va_end(params);
 258 }
 259
 260 static void print_advice(void)
 261 {
 262         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 263
 264         if (msg) {
 265                 fprintf(stderr, "%s\n", msg);
 266                 return;
 267         }
 268
 269         advise("after resolving the conflicts, mark the corrected paths");
 270         advise("with 'git add <paths>' or 'git rm <paths>'");
 271
 272         if (action == CHERRY_PICK)
 273                 advise("and commit the result with 'git commit -c %s'",
 274                        find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 275 }
 276
 277 static void write_message(struct strbuf *msgbuf, const char *filename)
 278 {
 279         static struct lock_file msg_file;
 280
 281         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 282                                                LOCK_DIE_ON_ERROR);
 283         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 284                 die_errno("Could not write to %s.", filename);
 285         strbuf_release(msgbuf);
 286         if (commit_lock_file(&msg_file) < 0)
 287                 die("Error wrapping up %s", filename);
 288 }
 289
 290 static struct tree *empty_tree(void)
 291 {
 292         struct tree *tree = xcalloc(1, sizeof(struct tree));
 293
 294         tree->object.parsed = 1;
 295         tree->object.type = OBJ_TREE;
 296         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 297         return tree;
 298 }
 299
 300 static NORETURN void die_dirty_index(const char *me)
 301 {
 302         if (read_cache_unmerged()) {
 303                 die_resolve_conflict(me);
 304         } else {
 305                 if (advice_commit_before_merge)
 306                         die("Your local changes would be overwritten by %s.\n"
 307                             "Please, commit your changes or stash them to proceed.", me);
 308                 else
 309                         die("Your local changes would be overwritten by %s.\n", me);
 310         }
 311 }
 312
 313 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 314 {
 315         struct ref_lock *ref_lock;
 316
 317         read_cache();
 318         if (checkout_fast_forward(from, to))
 319                 exit(1); /* the callee should have complained already */
 320         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 321         return write_ref_sha1(ref_lock, to, "cherry-pick");
 322 }
 323
 324 static int do_recursive_merge(struct commit *base, struct commit *next,
 325                               const char *base_label, const char *next_label,
 326                               unsigned char *head, struct strbuf *msgbuf)
 327 {
 328         struct merge_options o;
 329         struct tree *result, *next_tree, *base_tree, *head_tree;
 330         int clean, index_fd;
 331         const char **xopt;
 332         static struct lock_file index_lock;
 333
 334         index_fd = hold_locked_index(&index_lock, 1);
 335
 336         read_cache();
 337
 338         init_merge_options(&o);
 339         o.ancestor = base ? base_label : "(empty tree)";
 340         o.branch1 = "HEAD";
 341         o.branch2 = next ? next_label : "(empty tree)";
 342
 343         head_tree = parse_tree_indirect(head);
 344         next_tree = next ? next->tree : empty_tree();
 345         base_tree = base ? base->tree : empty_tree();
 346
 347         for (xopt = xopts; xopt != xopts + xopts_nr; xopt++)
 348                 parse_merge_opt(&o, *xopt);
 349
 350         clean = merge_trees(&o,
 351                             head_tree,
 352                             next_tree, base_tree, &result);
 353
 354         if (active_cache_changed &&
 355             (write_cache(index_fd, active_cache, active_nr) ||
 356              commit_locked_index(&index_lock)))
 357                 die("%s: Unable to write new index file", me);
 358         rollback_lock_file(&index_lock);
 359
 360         if (!clean) {
 361                 int i;
 362                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 363                 for (i = 0; i < active_nr;) {
 364                         struct cache_entry *ce = active_cache[i++];
 365                         if (ce_stage(ce)) {
 366                                 strbuf_addch(msgbuf, '\t');
 367                                 strbuf_addstr(msgbuf, ce->name);
 368                                 strbuf_addch(msgbuf, '\n');
 369                                 while (i < active_nr && !strcmp(ce->name,
 370                                                 active_cache[i]->name))
 371                                         i++;
 372                         }
 373                 }
 374         }
 375
 376         return !clean;
 377 }
 378
 379 /*
 380  * If we are cherry-pick, and if the merge did not result in
 381  * hand-editing, we will hit this commit and inherit the original
 382  * author date and name.
 383  * If we are revert, or if our cherry-pick results in a hand merge,
 384  * we had better say that the current user is responsible for that.
 385  */
 386 static int run_git_commit(const char *defmsg)
 387 {
 388         /* 6 is max possible length of our args array including NULL */
 389         const char *args[6];
 390         int i = 0;
 391
 392         args[i++] = "commit";
 393         args[i++] = "-n";
 394         if (signoff)
 395                 args[i++] = "-s";
 396         if (!edit) {
 397                 args[i++] = "-F";
 398                 args[i++] = defmsg;
 399         }
 400         args[i] = NULL;
 401
 402         return run_command_v_opt(args, RUN_GIT_CMD);
 403 }
 404
 405 static int do_pick_commit(void)
 406 {
 407         unsigned char head[20];
 408         struct commit *base, *next, *parent;
 409         const char *base_label, *next_label;
 410         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 411         char *defmsg = NULL;
 412         struct strbuf msgbuf = STRBUF_INIT;
 413         int res;
 414
 415         if (no_commit) {
 416                 /*
 417                  * We do not intend to commit immediately.  We just want to
 418                  * merge the differences in, so let's compute the tree
 419                  * that represents the "current" state for merge-recursive
 420                  * to work on.
 421                  */
 422                 if (write_cache_as_tree(head, 0, NULL))
 423                         die ("Your index file is unmerged.");
 424         } else {
 425                 if (get_sha1("HEAD", head))
 426                         die ("You do not have a valid HEAD");
 427                 if (index_differs_from("HEAD", 0))
 428                         die_dirty_index(me);
 429         }
 430         discard_cache();
 431
 432         if (!commit->parents) {
 433                 if (action == REVERT)
 434                         die ("Cannot revert a root commit");
 435                 parent = NULL;
 436         }
 437         else if (commit->parents->next) {
 438                 /* Reverting or cherry-picking a merge commit */
 439                 int cnt;
 440                 struct commit_list *p;
 441
 442                 if (!mainline)
 443                         die("Commit %s is a merge but no -m option was given.",
 444                             sha1_to_hex(commit->object.sha1));
 445
 446                 for (cnt = 1, p = commit->parents;
 447                      cnt != mainline && p;
 448                      cnt++)
 449                         p = p->next;
 450                 if (cnt != mainline || !p)
 451                         die("Commit %s does not have parent %d",
 452                             sha1_to_hex(commit->object.sha1), mainline);
 453                 parent = p->item;
 454         } else if (0 < mainline)
 455                 die("Mainline was specified but commit %s is not a merge.",
 456                     sha1_to_hex(commit->object.sha1));
 457         else
 458                 parent = commit->parents->item;
 459
 460         if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
 461                 return fast_forward_to(commit->object.sha1, head);
 462
 463         if (parent && parse_commit(parent) < 0)
 464                 die("%s: cannot parse parent commit %s",
 465                     me, sha1_to_hex(parent->object.sha1));
 466
 467         if (get_message(commit->buffer, &msg) != 0)
 468                 die("Cannot get commit message for %s",
 469                                 sha1_to_hex(commit->object.sha1));
 470
 471         /*
 472          * "commit" is an existing commit.  We would want to apply
 473          * the difference it introduces since its first parent "prev"
 474          * on top of the current HEAD if we are cherry-pick.  Or the
 475          * reverse of it if we are revert.
 476          */
 477
 478         defmsg = git_pathdup("MERGE_MSG");
 479
 480         if (action == REVERT) {
 481                 base = commit;
 482                 base_label = msg.label;
 483                 next = parent;
 484                 next_label = msg.parent_label;
 485                 strbuf_addstr(&msgbuf, "Revert \"");
 486                 strbuf_addstr(&msgbuf, msg.subject);
 487                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 488                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 489
 490                 if (commit->parents->next) {
 491                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 492                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 493                 }
 494                 strbuf_addstr(&msgbuf, ".\n");
 495         } else {
 496                 base = parent;
 497                 base_label = msg.parent_label;
 498                 next = commit;
 499                 next_label = msg.label;
 500                 set_author_ident_env(msg.message);
 501                 add_message_to_msg(&msgbuf, msg.message);
 502                 if (no_replay) {
 503                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 504                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 505                         strbuf_addstr(&msgbuf, ")\n");
 506                 }
 507         }
 508
 509         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 510                 res = do_recursive_merge(base, next, base_label, next_label,
 511                                          head, &msgbuf);
 512                 write_message(&msgbuf, defmsg);
 513         } else {
 514                 struct commit_list *common = NULL;
 515                 struct commit_list *remotes = NULL;
 516
 517                 write_message(&msgbuf, defmsg);
 518
 519                 commit_list_insert(base, &common);
 520                 commit_list_insert(next, &remotes);
 521                 res = try_merge_command(strategy, xopts_nr, xopts, common,
 522                                         sha1_to_hex(head), remotes);
 523                 free_commit_list(common);
 524                 free_commit_list(remotes);
 525         }
 526
 527         if (res) {
 528                 error("could not %s %s... %s",
 529                       action == REVERT ? "revert" : "apply",
 530                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 531                       msg.subject);
 532                 print_advice();
 533                 rerere(allow_rerere_auto);
 534         } else {
 535                 if (!no_commit)
 536                         res = run_git_commit(defmsg);
 537         }
 538
 539         free_message(&msg);
 540         free(defmsg);
 541
 542         return res;
 543 }
 544
 545 static void prepare_revs(struct rev_info *revs)
 546 {
 547         int argc;
 548
 549         init_revisions(revs, NULL);
 550         revs->no_walk = 1;
 551         if (action != REVERT)
 552                 revs->reverse = 1;
 553
 554         argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
 555         if (argc > 1)
 556                 usage(*revert_or_cherry_pick_usage());
 557
 558         if (prepare_revision_walk(revs))
 559                 die("revision walk setup failed");
 560
 561         if (!revs->commits)
 562                 die("empty commit set passed");
 563 }
 564
 565 static void read_and_refresh_cache(const char *me)
 566 {
 567         static struct lock_file index_lock;
 568         int index_fd = hold_locked_index(&index_lock, 0);
 569         if (read_index_preload(&the_index, NULL) < 0)
 570                 die("git %s: failed to read the index", me);
 571         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 572         if (the_index.cache_changed) {
 573                 if (write_index(&the_index, index_fd) ||
 574                     commit_locked_index(&index_lock))
 575                         die("git %s: failed to refresh the index", me);
 576         }
 577         rollback_lock_file(&index_lock);
 578 }
 579
 580 static int revert_or_cherry_pick(int argc, const char **argv)
 581 {
 582         struct rev_info revs;
 583
 584         git_config(git_default_config, NULL);
 585         me = action == REVERT ? "revert" : "cherry-pick";
 586         setenv(GIT_REFLOG_ACTION, me, 0);
 587         parse_args(argc, argv);
 588
 589         if (allow_ff) {
 590                 if (signoff)
 591                         die("cherry-pick --ff cannot be used with --signoff");
 592                 if (no_commit)
 593                         die("cherry-pick --ff cannot be used with --no-commit");
 594                 if (no_replay)
 595                         die("cherry-pick --ff cannot be used with -x");
 596                 if (edit)
 597                         die("cherry-pick --ff cannot be used with --edit");
 598         }
 599
 600         read_and_refresh_cache(me);
 601
 602         prepare_revs(&revs);
 603
 604         while ((commit = get_revision(&revs))) {
 605                 int res = do_pick_commit();
 606                 if (res)
 607                         return res;
 608         }
 609
 610         return 0;
 611 }
 612
 613 int cmd_revert(int argc, const char **argv, const char *prefix)
 614 {
 615         if (isatty(0))
 616                 edit = 1;
 617         action = REVERT;
 618         return revert_or_cherry_pick(argc, argv);
 619 }
 620
 621 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 622 {
 623         action = CHERRY_PICK;
 624         return revert_or_cherry_pick(argc, argv);
 625 }