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 void parse_args(int argc, const char **argv)
  54 {
  55         const char * const * usage_str =
  56                 action == REVERT ?  revert_usage : cherry_pick_usage;
  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('r', NULL, &noop, "no-op (backward compatibility)"),
  62                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  63                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  64                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  65                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
  66                 OPT_END(),
  67                 OPT_END(),
  68                 OPT_END(),
  69         };
  70
  71         if (action == CHERRY_PICK) {
  72                 struct option cp_extra[] = {
  73                         OPT_BOOLEAN('x', NULL, &no_replay, "append commit name"),
  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         commit_argc = parse_options(argc, argv, NULL, options, usage_str, 0);
  82         if (commit_argc < 1)
  83                 usage_with_options(usage_str, options);
  84
  85         commit_argv = argv;
  86 }
  87
  88 struct commit_message {
  89         char *parent_label;
  90         const char *label;
  91         const char *subject;
  92         char *reencoded_message;
  93         const char *message;
  94 };
  95
  96 static int get_message(const char *raw_message, struct commit_message *out)
  97 {
  98         const char *encoding;
  99         const char *p, *abbrev, *eol;
 100         char *q;
 101         int abbrev_len, oneline_len;
 102
 103         if (!raw_message)
 104                 return -1;
 105         encoding = get_encoding(raw_message);
 106         if (!encoding)
 107                 encoding = "UTF-8";
 108         if (!git_commit_encoding)
 109                 git_commit_encoding = "UTF-8";
 110
 111         out->reencoded_message = NULL;
 112         out->message = raw_message;
 113         if (strcmp(encoding, git_commit_encoding))
 114                 out->reencoded_message = reencode_string(raw_message,
 115                                         git_commit_encoding, encoding);
 116         if (out->reencoded_message)
 117                 out->message = out->reencoded_message;
 118
 119         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 120         abbrev_len = strlen(abbrev);
 121
 122         /* Find beginning and end of commit subject. */
 123         p = out->message;
 124         while (*p && (*p != '\n' || p[1] != '\n'))
 125                 p++;
 126         if (*p) {
 127                 p += 2;
 128                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 129                         ; /* do nothing */
 130         } else
 131                 eol = p;
 132         oneline_len = eol - p;
 133
 134         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 135                               strlen("... ") + oneline_len + 1);
 136         q = out->parent_label;
 137         q = mempcpy(q, "parent of ", strlen("parent of "));
 138         out->label = q;
 139         q = mempcpy(q, abbrev, abbrev_len);
 140         q = mempcpy(q, "... ", strlen("... "));
 141         out->subject = q;
 142         q = mempcpy(q, p, oneline_len);
 143         *q = '\0';
 144         return 0;
 145 }
 146
 147 static void free_message(struct commit_message *msg)
 148 {
 149         free(msg->parent_label);
 150         free(msg->reencoded_message);
 151 }
 152
 153 static char *get_encoding(const char *message)
 154 {
 155         const char *p = message, *eol;
 156
 157         if (!p)
 158                 die ("Could not read commit message of %s",
 159                                 sha1_to_hex(commit->object.sha1));
 160         while (*p && *p != '\n') {
 161                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 162                         ; /* do nothing */
 163                 if (!prefixcmp(p, "encoding ")) {
 164                         char *result = xmalloc(eol - 8 - p);
 165                         strlcpy(result, p + 9, eol - 8 - p);
 166                         return result;
 167                 }
 168                 p = eol;
 169                 if (*p == '\n')
 170                         p++;
 171         }
 172         return NULL;
 173 }
 174
 175 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 176 {
 177         const char *p = message;
 178         while (*p && (*p != '\n' || p[1] != '\n'))
 179                 p++;
 180
 181         if (!*p)
 182                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 183
 184         p += 2;
 185         strbuf_addstr(msgbuf, p);
 186 }
 187
 188 static void set_author_ident_env(const char *message)
 189 {
 190         const char *p = message;
 191         if (!p)
 192                 die ("Could not read commit message of %s",
 193                                 sha1_to_hex(commit->object.sha1));
 194         while (*p && *p != '\n') {
 195                 const char *eol;
 196
 197                 for (eol = p; *eol && *eol != '\n'; eol++)
 198                         ; /* do nothing */
 199                 if (!prefixcmp(p, "author ")) {
 200                         char *line, *pend, *email, *timestamp;
 201
 202                         p += 7;
 203                         line = xmemdupz(p, eol - p);
 204                         email = strchr(line, '<');
 205                         if (!email)
 206                                 die ("Could not extract author email from %s",
 207                                         sha1_to_hex(commit->object.sha1));
 208                         if (email == line)
 209                                 pend = line;
 210                         else
 211                                 for (pend = email; pend != line + 1 &&
 212                                                 isspace(pend[-1]); pend--);
 213                                         ; /* do nothing */
 214                         *pend = '\0';
 215                         email++;
 216                         timestamp = strchr(email, '>');
 217                         if (!timestamp)
 218                                 die ("Could not extract author time from %s",
 219                                         sha1_to_hex(commit->object.sha1));
 220                         *timestamp = '\0';
 221                         for (timestamp++; *timestamp && isspace(*timestamp);
 222                                         timestamp++)
 223                                 ; /* do nothing */
 224                         setenv("GIT_AUTHOR_NAME", line, 1);
 225                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 226                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 227                         free(line);
 228                         return;
 229                 }
 230                 p = eol;
 231                 if (*p == '\n')
 232                         p++;
 233         }
 234         die ("No author information found in %s",
 235                         sha1_to_hex(commit->object.sha1));
 236 }
 237
 238 static char *help_msg(void)
 239 {
 240         struct strbuf helpbuf = STRBUF_INIT;
 241         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 242
 243         if (msg)
 244                 return msg;
 245
 246         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 247                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 248                 "and commit the result");
 249
 250         if (action == CHERRY_PICK) {
 251                 strbuf_addf(&helpbuf, " with: \n"
 252                         "\n"
 253                         "        git commit -c %s\n",
 254                             sha1_to_hex(commit->object.sha1));
 255         }
 256         else
 257                 strbuf_addch(&helpbuf, '.');
 258         return strbuf_detach(&helpbuf, NULL);
 259 }
 260
 261 static void write_message(struct strbuf *msgbuf, const char *filename)
 262 {
 263         static struct lock_file msg_file;
 264
 265         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 266                                                LOCK_DIE_ON_ERROR);
 267         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 268                 die_errno("Could not write to %s.", filename);
 269         strbuf_release(msgbuf);
 270         if (commit_lock_file(&msg_file) < 0)
 271                 die("Error wrapping up %s", filename);
 272 }
 273
 274 static struct tree *empty_tree(void)
 275 {
 276         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 277 }
 278
 279 static NORETURN void die_dirty_index(const char *me)
 280 {
 281         if (read_cache_unmerged()) {
 282                 die_resolve_conflict(me);
 283         } else {
 284                 if (advice_commit_before_merge)
 285                         die("Your local changes would be overwritten by %s.\n"
 286                             "Please, commit your changes or stash them to proceed.", me);
 287                 else
 288                         die("Your local changes would be overwritten by %s.\n", me);
 289         }
 290 }
 291
 292 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 293 {
 294         struct ref_lock *ref_lock;
 295
 296         read_cache();
 297         if (checkout_fast_forward(from, to))
 298                 exit(1); /* the callee should have complained already */
 299         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 300         return write_ref_sha1(ref_lock, to, "cherry-pick");
 301 }
 302
 303 static void do_recursive_merge(struct commit *base, struct commit *next,
 304                                const char *base_label, const char *next_label,
 305                                unsigned char *head, struct strbuf *msgbuf,
 306                                char *defmsg)
 307 {
 308         struct merge_options o;
 309         struct tree *result, *next_tree, *base_tree, *head_tree;
 310         int clean, index_fd;
 311         static struct lock_file index_lock;
 312
 313         index_fd = hold_locked_index(&index_lock, 1);
 314
 315         read_cache();
 316         init_merge_options(&o);
 317         o.ancestor = base ? base_label : "(empty tree)";
 318         o.branch1 = "HEAD";
 319         o.branch2 = next ? next_label : "(empty tree)";
 320
 321         head_tree = parse_tree_indirect(head);
 322         next_tree = next ? next->tree : empty_tree();
 323         base_tree = base ? base->tree : empty_tree();
 324
 325         clean = merge_trees(&o,
 326                             head_tree,
 327                             next_tree, base_tree, &result);
 328
 329         if (active_cache_changed &&
 330             (write_cache(index_fd, active_cache, active_nr) ||
 331              commit_locked_index(&index_lock)))
 332                 die("%s: Unable to write new index file", me);
 333         rollback_lock_file(&index_lock);
 334
 335         if (!clean) {
 336                 int i;
 337                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 338                 for (i = 0; i < active_nr;) {
 339                         struct cache_entry *ce = active_cache[i++];
 340                         if (ce_stage(ce)) {
 341                                 strbuf_addch(msgbuf, '\t');
 342                                 strbuf_addstr(msgbuf, ce->name);
 343                                 strbuf_addch(msgbuf, '\n');
 344                                 while (i < active_nr && !strcmp(ce->name,
 345                                                 active_cache[i]->name))
 346                                         i++;
 347                         }
 348                 }
 349                 write_message(msgbuf, defmsg);
 350                 fprintf(stderr, "Automatic %s failed.%s\n",
 351                         me, help_msg());
 352                 rerere(allow_rerere_auto);
 353                 exit(1);
 354         }
 355         write_message(msgbuf, defmsg);
 356         fprintf(stderr, "Finished one %s.\n", me);
 357 }
 358
 359 static int do_pick_commit(void)
 360 {
 361         unsigned char head[20];
 362         struct commit *base, *next, *parent;
 363         const char *base_label, *next_label;
 364         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 365         char *defmsg = NULL;
 366         struct strbuf msgbuf = STRBUF_INIT;
 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 && !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                 set_author_ident_env(msg.message);
 454                 add_message_to_msg(&msgbuf, msg.message);
 455                 if (no_replay) {
 456                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 457                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 458                         strbuf_addstr(&msgbuf, ")\n");
 459                 }
 460         }
 461
 462         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT)
 463                 do_recursive_merge(base, next, base_label, next_label,
 464                                    head, &msgbuf, defmsg);
 465         else {
 466                 int res;
 467                 struct commit_list *common = NULL;
 468                 struct commit_list *remotes = NULL;
 469                 write_message(&msgbuf, defmsg);
 470                 commit_list_insert(base, &common);
 471                 commit_list_insert(next, &remotes);
 472                 res = try_merge_command(strategy, common,
 473                                         sha1_to_hex(head), remotes);
 474                 free_commit_list(common);
 475                 free_commit_list(remotes);
 476                 if (res) {
 477                         fprintf(stderr, "Automatic %s with strategy %s failed.%s\n",
 478                                 me, strategy, help_msg());
 479                         rerere(allow_rerere_auto);
 480                         exit(1);
 481                 }
 482         }
 483
 484         free_message(&msg);
 485
 486         /*
 487          *
 488          * If we are cherry-pick, and if the merge did not result in
 489          * hand-editing, we will hit this commit and inherit the original
 490          * author date and name.
 491          * If we are revert, or if our cherry-pick results in a hand merge,
 492          * we had better say that the current user is responsible for that.
 493          */
 494
 495         if (!no_commit) {
 496                 /* 6 is max possible length of our args array including NULL */
 497                 const char *args[6];
 498                 int res;
 499                 int i = 0;
 500
 501                 args[i++] = "commit";
 502                 args[i++] = "-n";
 503                 if (signoff)
 504                         args[i++] = "-s";
 505                 if (!edit) {
 506                         args[i++] = "-F";
 507                         args[i++] = defmsg;
 508                 }
 509                 args[i] = NULL;
 510                 res = run_command_v_opt(args, RUN_GIT_CMD);
 511                 free(defmsg);
 512
 513                 return res;
 514         }
 515
 516         free(defmsg);
 517
 518         return 0;
 519 }
 520
 521 static void prepare_revs(struct rev_info *revs)
 522 {
 523         int argc = 0;
 524         int i;
 525         const char **argv = xmalloc((commit_argc + 4) * sizeof(*argv));
 526
 527         argv[argc++] = NULL;
 528         argv[argc++] = "--no-walk";
 529         if (action != REVERT)
 530                 argv[argc++] = "--reverse";
 531         for (i = 0; i < commit_argc; i++)
 532                 argv[argc++] = commit_argv[i];
 533         argv[argc++] = NULL;
 534
 535         init_revisions(revs, NULL);
 536         setup_revisions(argc - 1, argv, revs, NULL);
 537         if (prepare_revision_walk(revs))
 538                 die("revision walk setup failed");
 539
 540         if (!revs->commits)
 541                 die("empty commit set passed");
 542
 543         free(argv);
 544 }
 545
 546 static int revert_or_cherry_pick(int argc, const char **argv)
 547 {
 548         struct rev_info revs;
 549
 550         git_config(git_default_config, NULL);
 551         me = action == REVERT ? "revert" : "cherry-pick";
 552         setenv(GIT_REFLOG_ACTION, me, 0);
 553         parse_args(argc, argv);
 554
 555         if (allow_ff) {
 556                 if (signoff)
 557                         die("cherry-pick --ff cannot be used with --signoff");
 558                 if (no_commit)
 559                         die("cherry-pick --ff cannot be used with --no-commit");
 560                 if (no_replay)
 561                         die("cherry-pick --ff cannot be used with -x");
 562                 if (edit)
 563                         die("cherry-pick --ff cannot be used with --edit");
 564         }
 565
 566         if (read_cache() < 0)
 567                 die("git %s: failed to read the index", me);
 568
 569         prepare_revs(&revs);
 570
 571         while ((commit = get_revision(&revs))) {
 572                 int res = do_pick_commit();
 573                 if (res)
 574                         return res;
 575         }
 576
 577         return 0;
 578 }
 579
 580 int cmd_revert(int argc, const char **argv, const char *prefix)
 581 {
 582         if (isatty(0))
 583                 edit = 1;
 584         action = REVERT;
 585         return revert_or_cherry_pick(argc, argv);
 586 }
 587
 588 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 589 {
 590         action = CHERRY_PICK;
 591         return revert_or_cherry_pick(argc, argv);
 592 }