builtin/revert.c

   1 #include "cache.h"
   2 #include "builtin.h"
   3 #include "object.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "wt-status.h"
   7 #include "run-command.h"
   8 #include "exec_cmd.h"
   9 #include "utf8.h"
  10 #include "parse-options.h"
  11 #include "cache-tree.h"
  12 #include "diff.h"
  13 #include "revision.h"
  14 #include "rerere.h"
  15 #include "merge-recursive.h"
  16 #include "refs.h"
  17
  18 /*
  19  * This implements the builtins revert and cherry-pick.
  20  *
  21  * Copyright (c) 2007 Johannes E. Schindelin
  22  *
  23  * Based on git-revert.sh, which is
  24  *
  25  * Copyright (c) 2005 Linus Torvalds
  26  * Copyright (c) 2005 Junio C Hamano
  27  */
  28
  29 static const char * const revert_usage[] = {
  30         "git revert [options] <commit-ish>",
  31         NULL
  32 };
  33
  34 static const char * const cherry_pick_usage[] = {
  35         "git cherry-pick [options] <commit-ish>",
  36         NULL
  37 };
  38
  39 static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
  40 static enum { REVERT, CHERRY_PICK } action;
  41 static struct commit *commit;
  42 static const char *commit_name;
  43 static int allow_rerere_auto;
  44
  45 static const char *me;
  46 static const char *strategy;
  47
  48 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  49
  50 static char *get_encoding(const char *message);
  51
  52 static void parse_args(int argc, const char **argv)
  53 {
  54         const char * const * usage_str =
  55                 action == REVERT ?  revert_usage : cherry_pick_usage;
  56         unsigned char sha1[20];
  57         int noop;
  58         struct option options[] = {
  59                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  60                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  61                 OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
  62                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  63                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  64                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  65                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  66                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
  67                 OPT_END(),
  68                 OPT_END(),
  69                 OPT_END(),
  70         };
  71
  72         if (action == CHERRY_PICK) {
  73                 struct option cp_extra[] = {
  74                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
  75                         OPT_END(),
  76                 };
  77                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
  78                         die("program error");
  79         }
  80
  81         if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
  82                 usage_with_options(usage_str, options);
  83
  84         commit_name = argv[0];
  85         if (get_sha1(commit_name, sha1))
  86                 die ("Cannot find '%s'", commit_name);
  87         commit = lookup_commit_reference(sha1);
  88         if (!commit)
  89                 exit(1);
  90 }
  91
  92 struct commit_message {
  93         char *parent_label;
  94         const char *label;
  95         const char *subject;
  96         char *reencoded_message;
  97         const char *message;
  98 };
  99
 100 static int get_message(const char *raw_message, struct commit_message *out)
 101 {
 102         const char *encoding;
 103         const char *p, *abbrev, *eol;
 104         char *q;
 105         int abbrev_len, oneline_len;
 106
 107         if (!raw_message)
 108                 return -1;
 109         encoding = get_encoding(raw_message);
 110         if (!encoding)
 111                 encoding = "UTF-8";
 112         if (!git_commit_encoding)
 113                 git_commit_encoding = "UTF-8";
 114         if ((out->reencoded_message = reencode_string(raw_message,
 115                                         git_commit_encoding, encoding)))
 116                 out->message = out->reencoded_message;
 117
 118         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 119         abbrev_len = strlen(abbrev);
 120
 121         /* Find beginning and end of commit subject. */
 122         p = out->message;
 123         while (*p && (*p != '\n' || p[1] != '\n'))
 124                 p++;
 125         if (*p) {
 126                 p += 2;
 127                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 128                         ; /* do nothing */
 129         } else
 130                 eol = p;
 131         oneline_len = eol - p;
 132
 133         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 134                               strlen("... ") + oneline_len + 1);
 135         q = out->parent_label;
 136         q = mempcpy(q, "parent of ", strlen("parent of "));
 137         out->label = q;
 138         q = mempcpy(q, abbrev, abbrev_len);
 139         q = mempcpy(q, "... ", strlen("... "));
 140         out->subject = q;
 141         q = mempcpy(q, p, oneline_len);
 142         *q = '\0';
 143         return 0;
 144 }
 145
 146 static void free_message(struct commit_message *msg)
 147 {
 148         free(msg->parent_label);
 149         free(msg->reencoded_message);
 150 }
 151
 152 static char *get_encoding(const char *message)
 153 {
 154         const char *p = message, *eol;
 155
 156         if (!p)
 157                 die ("Could not read commit message of %s",
 158                                 sha1_to_hex(commit->object.sha1));
 159         while (*p && *p != '\n') {
 160                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 161                         ; /* do nothing */
 162                 if (!prefixcmp(p, "encoding ")) {
 163                         char *result = xmalloc(eol - 8 - p);
 164                         strlcpy(result, p + 9, eol - 8 - p);
 165                         return result;
 166                 }
 167                 p = eol;
 168                 if (*p == '\n')
 169                         p++;
 170         }
 171         return NULL;
 172 }
 173
 174 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 175 {
 176         const char *p = message;
 177         while (*p && (*p != '\n' || p[1] != '\n'))
 178                 p++;
 179
 180         if (!*p)
 181                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 182
 183         p += 2;
 184         strbuf_addstr(msgbuf, p);
 185 }
 186
 187 static void set_author_ident_env(const char *message)
 188 {
 189         const char *p = message;
 190         if (!p)
 191                 die ("Could not read commit message of %s",
 192                                 sha1_to_hex(commit->object.sha1));
 193         while (*p && *p != '\n') {
 194                 const char *eol;
 195
 196                 for (eol = p; *eol && *eol != '\n'; eol++)
 197                         ; /* do nothing */
 198                 if (!prefixcmp(p, "author ")) {
 199                         char *line, *pend, *email, *timestamp;
 200
 201                         p += 7;
 202                         line = xmemdupz(p, eol - p);
 203                         email = strchr(line, '<');
 204                         if (!email)
 205                                 die ("Could not extract author email from %s",
 206                                         sha1_to_hex(commit->object.sha1));
 207                         if (email == line)
 208                                 pend = line;
 209                         else
 210                                 for (pend = email; pend != line + 1 &&
 211                                                 isspace(pend[-1]); pend--);
 212                                         ; /* do nothing */
 213                         *pend = '\0';
 214                         email++;
 215                         timestamp = strchr(email, '>');
 216                         if (!timestamp)
 217                                 die ("Could not extract author time from %s",
 218                                         sha1_to_hex(commit->object.sha1));
 219                         *timestamp = '\0';
 220                         for (timestamp++; *timestamp && isspace(*timestamp);
 221                                         timestamp++)
 222                                 ; /* do nothing */
 223                         setenv("GIT_AUTHOR_NAME", line, 1);
 224                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 225                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 226                         free(line);
 227                         return;
 228                 }
 229                 p = eol;
 230                 if (*p == '\n')
 231                         p++;
 232         }
 233         die ("No author information found in %s",
 234                         sha1_to_hex(commit->object.sha1));
 235 }
 236
 237 static char *help_msg(const char *name)
 238 {
 239         struct strbuf helpbuf = STRBUF_INIT;
 240         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 241
 242         if (msg)
 243                 return msg;
 244
 245         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 246                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 247                 "and commit the result");
 248
 249         if (action == CHERRY_PICK) {
 250                 strbuf_addf(&helpbuf, " with: \n"
 251                         "\n"
 252                         "        git commit -c %s\n",
 253                         name);
 254         }
 255         else
 256                 strbuf_addch(&helpbuf, '.');
 257         return strbuf_detach(&helpbuf, NULL);
 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 void 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                                char *defmsg)
 311 {
 312         struct merge_options o;
 313         struct tree *result, *next_tree, *base_tree, *head_tree;
 314         int clean, index_fd;
 315         static struct lock_file index_lock;
 316
 317         index_fd = hold_locked_index(&index_lock, 1);
 318
 319         read_cache();
 320         init_merge_options(&o);
 321         o.ancestor = base ? base_label : "(empty tree)";
 322         o.branch1 = "HEAD";
 323         o.branch2 = next ? next_label : "(empty tree)";
 324
 325         head_tree = parse_tree_indirect(head);
 326         next_tree = next ? next->tree : empty_tree();
 327         base_tree = base ? base->tree : empty_tree();
 328
 329         clean = merge_trees(&o,
 330                             head_tree,
 331                             next_tree, base_tree, &result);
 332
 333         if (active_cache_changed &&
 334             (write_cache(index_fd, active_cache, active_nr) ||
 335              commit_locked_index(&index_lock)))
 336                 die("%s: Unable to write new index file", me);
 337         rollback_lock_file(&index_lock);
 338
 339         if (!clean) {
 340                 int i;
 341                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 342                 for (i = 0; i < active_nr;) {
 343                         struct cache_entry *ce = active_cache[i++];
 344                         if (ce_stage(ce)) {
 345                                 strbuf_addch(msgbuf, '\t');
 346                                 strbuf_addstr(msgbuf, ce->name);
 347                                 strbuf_addch(msgbuf, '\n');
 348                                 while (i < active_nr && !strcmp(ce->name,
 349                                                 active_cache[i]->name))
 350                                         i++;
 351                         }
 352                 }
 353                 write_message(msgbuf, defmsg);
 354                 fprintf(stderr, "Automatic %s failed.%s\n",
 355                         me, help_msg(commit_name));
 356                 rerere(allow_rerere_auto);
 357                 exit(1);
 358         }
 359         write_message(msgbuf, defmsg);
 360         fprintf(stderr, "Finished one %s.\n", me);
 361 }
 362
 363 static int revert_or_cherry_pick(int argc, const char **argv)
 364 {
 365         unsigned char head[20];
 366         struct commit *base, *next, *parent;
 367         const char *base_label, *next_label;
 368         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 369         char *defmsg = NULL;
 370         struct strbuf msgbuf = STRBUF_INIT;
 371
 372         git_config(git_default_config, NULL);
 373         me = action == REVERT ? "revert" : "cherry-pick";
 374         setenv(GIT_REFLOG_ACTION, me, 0);
 375         parse_args(argc, argv);
 376
 377         /* this is copied from the shell script, but it's never triggered... */
 378         if (action == REVERT && !no_replay)
 379                 die("revert is incompatible with replay");
 380
 381         if (allow_ff) {
 382                 if (signoff)
 383                         die("cherry-pick --ff cannot be used with --signoff");
 384                 if (no_commit)
 385                         die("cherry-pick --ff cannot be used with --no-commit");
 386                 if (no_replay)
 387                         die("cherry-pick --ff cannot be used with -x");
 388                 if (edit)
 389                         die("cherry-pick --ff cannot be used with --edit");
 390         }
 391
 392         if (read_cache() < 0)
 393                 die("git %s: failed to read the index", me);
 394         if (no_commit) {
 395                 /*
 396                  * We do not intend to commit immediately.  We just want to
 397                  * merge the differences in, so let's compute the tree
 398                  * that represents the "current" state for merge-recursive
 399                  * to work on.
 400                  */
 401                 if (write_cache_as_tree(head, 0, NULL))
 402                         die ("Your index file is unmerged.");
 403         } else {
 404                 if (get_sha1("HEAD", head))
 405                         die ("You do not have a valid HEAD");
 406                 if (index_differs_from("HEAD", 0))
 407                         die_dirty_index(me);
 408         }
 409         discard_cache();
 410
 411         if (!commit->parents) {
 412                 if (action == REVERT)
 413                         die ("Cannot revert a root commit");
 414                 parent = NULL;
 415         }
 416         else if (commit->parents->next) {
 417                 /* Reverting or cherry-picking a merge commit */
 418                 int cnt;
 419                 struct commit_list *p;
 420
 421                 if (!mainline)
 422                         die("Commit %s is a merge but no -m option was given.",
 423                             sha1_to_hex(commit->object.sha1));
 424
 425                 for (cnt = 1, p = commit->parents;
 426                      cnt != mainline && p;
 427                      cnt++)
 428                         p = p->next;
 429                 if (cnt != mainline || !p)
 430                         die("Commit %s does not have parent %d",
 431                             sha1_to_hex(commit->object.sha1), mainline);
 432                 parent = p->item;
 433         } else if (0 < mainline)
 434                 die("Mainline was specified but commit %s is not a merge.",
 435                     sha1_to_hex(commit->object.sha1));
 436         else
 437                 parent = commit->parents->item;
 438
 439         if (allow_ff && !hashcmp(parent->object.sha1, head))
 440                 return fast_forward_to(commit->object.sha1, head);
 441
 442         if (parent && parse_commit(parent) < 0)
 443                 die("%s: cannot parse parent commit %s",
 444                     me, sha1_to_hex(parent->object.sha1));
 445
 446         if (get_message(commit->buffer, &msg) != 0)
 447                 die("Cannot get commit message for %s",
 448                                 sha1_to_hex(commit->object.sha1));
 449
 450         /*
 451          * "commit" is an existing commit.  We would want to apply
 452          * the difference it introduces since its first parent "prev"
 453          * on top of the current HEAD if we are cherry-pick.  Or the
 454          * reverse of it if we are revert.
 455          */
 456
 457         defmsg = git_pathdup("MERGE_MSG");
 458
 459         if (action == REVERT) {
 460                 base = commit;
 461                 base_label = msg.label;
 462                 next = parent;
 463                 next_label = msg.parent_label;
 464                 strbuf_addstr(&msgbuf, "Revert \"");
 465                 strbuf_addstr(&msgbuf, msg.subject);
 466                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 467                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 468
 469                 if (commit->parents->next) {
 470                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 471                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 472                 }
 473                 strbuf_addstr(&msgbuf, ".\n");
 474         } else {
 475                 base = parent;
 476                 base_label = msg.parent_label;
 477                 next = commit;
 478                 next_label = msg.label;
 479                 set_author_ident_env(msg.message);
 480                 add_message_to_msg(&msgbuf, msg.message);
 481                 if (no_replay) {
 482                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 483                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 484                         strbuf_addstr(&msgbuf, ")\n");
 485                 }
 486         }
 487
 488         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT)
 489                 do_recursive_merge(base, next, base_label, next_label,
 490                                    head, &msgbuf, defmsg);
 491         else {
 492                 int res;
 493                 struct commit_list *common = NULL;
 494                 struct commit_list *remotes = NULL;
 495                 write_message(&msgbuf, defmsg);
 496                 commit_list_insert(base, &common);
 497                 commit_list_insert(next, &remotes);
 498                 res = try_merge_command(strategy, common,
 499                                         sha1_to_hex(head), remotes);
 500                 free_commit_list(common);
 501                 free_commit_list(remotes);
 502                 if (res) {
 503                         fprintf(stderr, "Automatic %s with strategy %s failed.%s\n",
 504                                 me, strategy, help_msg(commit_name));
 505                         rerere(allow_rerere_auto);
 506                         exit(1);
 507                 }
 508         }
 509
 510         /*
 511          *
 512          * If we are cherry-pick, and if the merge did not result in
 513          * hand-editing, we will hit this commit and inherit the original
 514          * author date and name.
 515          * If we are revert, or if our cherry-pick results in a hand merge,
 516          * we had better say that the current user is responsible for that.
 517          */
 518
 519         if (!no_commit) {
 520                 /* 6 is max possible length of our args array including NULL */
 521                 const char *args[6];
 522                 int i = 0;
 523                 args[i++] = "commit";
 524                 args[i++] = "-n";
 525                 if (signoff)
 526                         args[i++] = "-s";
 527                 if (!edit) {
 528                         args[i++] = "-F";
 529                         args[i++] = defmsg;
 530                 }
 531                 args[i] = NULL;
 532                 return execv_git_cmd(args);
 533         }
 534         free_message(&msg);
 535         free(defmsg);
 536
 537         return 0;
 538 }
 539
 540 int cmd_revert(int argc, const char **argv, const char *prefix)
 541 {
 542         if (isatty(0))
 543                 edit = 1;
 544         no_replay = 1;
 545         action = REVERT;
 546         return revert_or_cherry_pick(argc, argv);
 547 }
 548
 549 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 550 {
 551         no_replay = 0;
 552         action = CHERRY_PICK;
 553         return revert_or_cherry_pick(argc, argv);
 554 }