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 *p, *abbrev, *eol;
 106         char *q;
 107         int abbrev_len, oneline_len;
 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         /* Find beginning and end of commit subject. */
 129         p = out->message;
 130         while (*p && (*p != '\n' || p[1] != '\n'))
 131                 p++;
 132         if (*p) {
 133                 p += 2;
 134                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 135                         ; /* do nothing */
 136         } else
 137                 eol = p;
 138         oneline_len = eol - p;
 139
 140         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 141                               strlen("... ") + oneline_len + 1);
 142         q = out->parent_label;
 143         q = mempcpy(q, "parent of ", strlen("parent of "));
 144         out->label = q;
 145         q = mempcpy(q, abbrev, abbrev_len);
 146         q = mempcpy(q, "... ", strlen("... "));
 147         out->subject = q;
 148         q = mempcpy(q, p, oneline_len);
 149         *q = '\0';
 150         return 0;
 151 }
 152
 153 static void free_message(struct commit_message *msg)
 154 {
 155         free(msg->parent_label);
 156         free(msg->reencoded_message);
 157 }
 158
 159 static char *get_encoding(const char *message)
 160 {
 161         const char *p = message, *eol;
 162
 163         if (!p)
 164                 die ("Could not read commit message of %s",
 165                                 sha1_to_hex(commit->object.sha1));
 166         while (*p && *p != '\n') {
 167                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 168                         ; /* do nothing */
 169                 if (!prefixcmp(p, "encoding ")) {
 170                         char *result = xmalloc(eol - 8 - p);
 171                         strlcpy(result, p + 9, eol - 8 - p);
 172                         return result;
 173                 }
 174                 p = eol;
 175                 if (*p == '\n')
 176                         p++;
 177         }
 178         return NULL;
 179 }
 180
 181 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 182 {
 183         const char *p = message;
 184         while (*p && (*p != '\n' || p[1] != '\n'))
 185                 p++;
 186
 187         if (!*p)
 188                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 189
 190         p += 2;
 191         strbuf_addstr(msgbuf, p);
 192 }
 193
 194 static void set_author_ident_env(const char *message)
 195 {
 196         const char *p = message;
 197         if (!p)
 198                 die ("Could not read commit message of %s",
 199                                 sha1_to_hex(commit->object.sha1));
 200         while (*p && *p != '\n') {
 201                 const char *eol;
 202
 203                 for (eol = p; *eol && *eol != '\n'; eol++)
 204                         ; /* do nothing */
 205                 if (!prefixcmp(p, "author ")) {
 206                         char *line, *pend, *email, *timestamp;
 207
 208                         p += 7;
 209                         line = xmemdupz(p, eol - p);
 210                         email = strchr(line, '<');
 211                         if (!email)
 212                                 die ("Could not extract author email from %s",
 213                                         sha1_to_hex(commit->object.sha1));
 214                         if (email == line)
 215                                 pend = line;
 216                         else
 217                                 for (pend = email; pend != line + 1 &&
 218                                                 isspace(pend[-1]); pend--);
 219                                         ; /* do nothing */
 220                         *pend = '\0';
 221                         email++;
 222                         timestamp = strchr(email, '>');
 223                         if (!timestamp)
 224                                 die ("Could not extract author time from %s",
 225                                         sha1_to_hex(commit->object.sha1));
 226                         *timestamp = '\0';
 227                         for (timestamp++; *timestamp && isspace(*timestamp);
 228                                         timestamp++)
 229                                 ; /* do nothing */
 230                         setenv("GIT_AUTHOR_NAME", line, 1);
 231                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 232                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 233                         free(line);
 234                         return;
 235                 }
 236                 p = eol;
 237                 if (*p == '\n')
 238                         p++;
 239         }
 240         die ("No author information found in %s",
 241                         sha1_to_hex(commit->object.sha1));
 242 }
 243
 244 static void advise(const char *advice, ...)
 245 {
 246         va_list params;
 247
 248         va_start(params, advice);
 249         vreportf("hint: ", advice, params);
 250         va_end(params);
 251 }
 252
 253 static char *help_msg(void)
 254 {
 255         struct strbuf helpbuf = STRBUF_INIT;
 256         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 257
 258         if (msg)
 259                 return msg;
 260
 261         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 262                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 263                 "and commit the result");
 264
 265         if (action == CHERRY_PICK) {
 266                 strbuf_addf(&helpbuf, " with: \n"
 267                         "\n"
 268                         "        git commit -c %s\n",
 269                             sha1_to_hex(commit->object.sha1));
 270         }
 271         else
 272                 strbuf_addch(&helpbuf, '.');
 273         return strbuf_detach(&helpbuf, NULL);
 274 }
 275
 276 static void write_message(struct strbuf *msgbuf, const char *filename)
 277 {
 278         static struct lock_file msg_file;
 279
 280         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 281                                                LOCK_DIE_ON_ERROR);
 282         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 283                 die_errno("Could not write to %s.", filename);
 284         strbuf_release(msgbuf);
 285         if (commit_lock_file(&msg_file) < 0)
 286                 die("Error wrapping up %s", filename);
 287 }
 288
 289 static struct tree *empty_tree(void)
 290 {
 291         struct tree *tree = xcalloc(1, sizeof(struct tree));
 292
 293         tree->object.parsed = 1;
 294         tree->object.type = OBJ_TREE;
 295         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 296         return tree;
 297 }
 298
 299 static NORETURN void die_dirty_index(const char *me)
 300 {
 301         if (read_cache_unmerged()) {
 302                 die_resolve_conflict(me);
 303         } else {
 304                 if (advice_commit_before_merge)
 305                         die("Your local changes would be overwritten by %s.\n"
 306                             "Please, commit your changes or stash them to proceed.", me);
 307                 else
 308                         die("Your local changes would be overwritten by %s.\n", me);
 309         }
 310 }
 311
 312 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 313 {
 314         struct ref_lock *ref_lock;
 315
 316         read_cache();
 317         if (checkout_fast_forward(from, to))
 318                 exit(1); /* the callee should have complained already */
 319         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 320         return write_ref_sha1(ref_lock, to, "cherry-pick");
 321 }
 322
 323 static int do_recursive_merge(struct commit *base, struct commit *next,
 324                               const char *base_label, const char *next_label,
 325                               unsigned char *head, struct strbuf *msgbuf)
 326 {
 327         struct merge_options o;
 328         struct tree *result, *next_tree, *base_tree, *head_tree;
 329         int clean, index_fd;
 330         static struct lock_file index_lock;
 331
 332         index_fd = hold_locked_index(&index_lock, 1);
 333
 334         read_cache();
 335         init_merge_options(&o);
 336         o.ancestor = base ? base_label : "(empty tree)";
 337         o.branch1 = "HEAD";
 338         o.branch2 = next ? next_label : "(empty tree)";
 339
 340         head_tree = parse_tree_indirect(head);
 341         next_tree = next ? next->tree : empty_tree();
 342         base_tree = base ? base->tree : empty_tree();
 343
 344         clean = merge_trees(&o,
 345                             head_tree,
 346                             next_tree, base_tree, &result);
 347
 348         if (active_cache_changed &&
 349             (write_cache(index_fd, active_cache, active_nr) ||
 350              commit_locked_index(&index_lock)))
 351                 die("%s: Unable to write new index file", me);
 352         rollback_lock_file(&index_lock);
 353
 354         if (!clean) {
 355                 int i;
 356                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 357                 for (i = 0; i < active_nr;) {
 358                         struct cache_entry *ce = active_cache[i++];
 359                         if (ce_stage(ce)) {
 360                                 strbuf_addch(msgbuf, '\t');
 361                                 strbuf_addstr(msgbuf, ce->name);
 362                                 strbuf_addch(msgbuf, '\n');
 363                                 while (i < active_nr && !strcmp(ce->name,
 364                                                 active_cache[i]->name))
 365                                         i++;
 366                         }
 367                 }
 368         }
 369
 370         return !clean;
 371 }
 372
 373 /*
 374  * If we are cherry-pick, and if the merge did not result in
 375  * hand-editing, we will hit this commit and inherit the original
 376  * author date and name.
 377  * If we are revert, or if our cherry-pick results in a hand merge,
 378  * we had better say that the current user is responsible for that.
 379  */
 380 static int run_git_commit(const char *defmsg)
 381 {
 382         /* 6 is max possible length of our args array including NULL */
 383         const char *args[6];
 384         int i = 0;
 385
 386         args[i++] = "commit";
 387         args[i++] = "-n";
 388         if (signoff)
 389                 args[i++] = "-s";
 390         if (!edit) {
 391                 args[i++] = "-F";
 392                 args[i++] = defmsg;
 393         }
 394         args[i] = NULL;
 395
 396         return run_command_v_opt(args, RUN_GIT_CMD);
 397 }
 398
 399 static int do_pick_commit(void)
 400 {
 401         unsigned char head[20];
 402         struct commit *base, *next, *parent;
 403         const char *base_label, *next_label;
 404         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 405         char *defmsg = NULL;
 406         struct strbuf msgbuf = STRBUF_INIT;
 407         struct strbuf mebuf = STRBUF_INIT;
 408         int res;
 409
 410         if (no_commit) {
 411                 /*
 412                  * We do not intend to commit immediately.  We just want to
 413                  * merge the differences in, so let's compute the tree
 414                  * that represents the "current" state for merge-recursive
 415                  * to work on.
 416                  */
 417                 if (write_cache_as_tree(head, 0, NULL))
 418                         die ("Your index file is unmerged.");
 419         } else {
 420                 if (get_sha1("HEAD", head))
 421                         die ("You do not have a valid HEAD");
 422                 if (index_differs_from("HEAD", 0))
 423                         die_dirty_index(me);
 424         }
 425         discard_cache();
 426
 427         if (!commit->parents) {
 428                 if (action == REVERT)
 429                         die ("Cannot revert a root commit");
 430                 parent = NULL;
 431         }
 432         else if (commit->parents->next) {
 433                 /* Reverting or cherry-picking a merge commit */
 434                 int cnt;
 435                 struct commit_list *p;
 436
 437                 if (!mainline)
 438                         die("Commit %s is a merge but no -m option was given.",
 439                             sha1_to_hex(commit->object.sha1));
 440
 441                 for (cnt = 1, p = commit->parents;
 442                      cnt != mainline && p;
 443                      cnt++)
 444                         p = p->next;
 445                 if (cnt != mainline || !p)
 446                         die("Commit %s does not have parent %d",
 447                             sha1_to_hex(commit->object.sha1), mainline);
 448                 parent = p->item;
 449         } else if (0 < mainline)
 450                 die("Mainline was specified but commit %s is not a merge.",
 451                     sha1_to_hex(commit->object.sha1));
 452         else
 453                 parent = commit->parents->item;
 454
 455         if (allow_ff && !hashcmp(parent->object.sha1, head))
 456                 return fast_forward_to(commit->object.sha1, head);
 457
 458         if (parent && parse_commit(parent) < 0)
 459                 die("%s: cannot parse parent commit %s",
 460                     me, sha1_to_hex(parent->object.sha1));
 461
 462         if (get_message(commit->buffer, &msg) != 0)
 463                 die("Cannot get commit message for %s",
 464                                 sha1_to_hex(commit->object.sha1));
 465
 466         /*
 467          * "commit" is an existing commit.  We would want to apply
 468          * the difference it introduces since its first parent "prev"
 469          * on top of the current HEAD if we are cherry-pick.  Or the
 470          * reverse of it if we are revert.
 471          */
 472
 473         defmsg = git_pathdup("MERGE_MSG");
 474
 475         if (action == REVERT) {
 476                 base = commit;
 477                 base_label = msg.label;
 478                 next = parent;
 479                 next_label = msg.parent_label;
 480                 strbuf_addstr(&msgbuf, "Revert \"");
 481                 strbuf_addstr(&msgbuf, msg.subject);
 482                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 483                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 484
 485                 if (commit->parents->next) {
 486                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 487                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 488                 }
 489                 strbuf_addstr(&msgbuf, ".\n");
 490         } else {
 491                 base = parent;
 492                 base_label = msg.parent_label;
 493                 next = commit;
 494                 next_label = msg.label;
 495                 set_author_ident_env(msg.message);
 496                 add_message_to_msg(&msgbuf, msg.message);
 497                 if (no_replay) {
 498                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 499                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 500                         strbuf_addstr(&msgbuf, ")\n");
 501                 }
 502         }
 503
 504         strbuf_addf(&mebuf, "%s of commit %s", me,
 505                     find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 506
 507         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
 508                 res = do_recursive_merge(base, next, base_label, next_label,
 509                                          head, &msgbuf);
 510                 write_message(&msgbuf, defmsg);
 511         } else {
 512                 struct commit_list *common = NULL;
 513                 struct commit_list *remotes = NULL;
 514
 515                 strbuf_addf(&mebuf, " with strategy %s", strategy);
 516                 write_message(&msgbuf, defmsg);
 517
 518                 commit_list_insert(base, &common);
 519                 commit_list_insert(next, &remotes);
 520                 res = try_merge_command(strategy, common,
 521                                         sha1_to_hex(head), remotes);
 522                 free_commit_list(common);
 523                 free_commit_list(remotes);
 524         }
 525
 526         if (res) {
 527                 error("could not %s %s... %s",
 528                       action == REVERT ? "revert" : "apply",
 529                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 530                       msg.subject);
 531                 fprintf(stderr, help_msg());
 532                 rerere(allow_rerere_auto);
 533         } else {
 534                 if (!no_commit)
 535                         res = run_git_commit(defmsg);
 536         }
 537
 538         strbuf_release(&mebuf);
 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 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         if (read_cache() < 0)
 586                 die("git %s: failed to read the index", me);
 587
 588         prepare_revs(&revs);
 589
 590         while ((commit = get_revision(&revs))) {
 591                 int res = do_pick_commit();
 592                 if (res)
 593                         return res;
 594         }
 595
 596         return 0;
 597 }
 598
 599 int cmd_revert(int argc, const char **argv, const char *prefix)
 600 {
 601         if (isatty(0))
 602                 edit = 1;
 603         action = REVERT;
 604         return revert_or_cherry_pick(argc, argv);
 605 }
 606
 607 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 608 {
 609         action = CHERRY_PICK;
 610         return revert_or_cherry_pick(argc, argv);
 611 }