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
  47 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  48
  49 static char *get_encoding(const char *message);
  50
  51 static void parse_args(int argc, const char **argv)
  52 {
  53         const char * const * usage_str =
  54                 action == REVERT ?  revert_usage : cherry_pick_usage;
  55         unsigned char sha1[20];
  56         int noop;
  57         struct option options[] = {
  58                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  59                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  60                 OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
  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_END(),
  66                 OPT_END(),
  67                 OPT_END(),
  68         };
  69
  70         if (action == CHERRY_PICK) {
  71                 struct option cp_extra[] = {
  72                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
  73                         OPT_END(),
  74                 };
  75                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
  76                         die("program error");
  77         }
  78
  79         if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
  80                 usage_with_options(usage_str, options);
  81
  82         commit_name = argv[0];
  83         if (get_sha1(commit_name, sha1))
  84                 die ("Cannot find '%s'", commit_name);
  85         commit = lookup_commit_reference(sha1);
  86         if (!commit)
  87                 exit(1);
  88 }
  89
  90 struct commit_message {
  91         char *parent_label;
  92         const char *label;
  93         const char *subject;
  94         char *reencoded_message;
  95         const char *message;
  96 };
  97
  98 static int get_message(const char *raw_message, struct commit_message *out)
  99 {
 100         const char *encoding;
 101         const char *p, *abbrev, *eol;
 102         char *q;
 103         int abbrev_len, oneline_len;
 104
 105         if (!raw_message)
 106                 return -1;
 107         encoding = get_encoding(raw_message);
 108         if (!encoding)
 109                 encoding = "UTF-8";
 110         if (!git_commit_encoding)
 111                 git_commit_encoding = "UTF-8";
 112
 113         out->reencoded_message = NULL;
 114         out->message = raw_message;
 115         if (strcmp(encoding, git_commit_encoding))
 116                 out->reencoded_message = reencode_string(raw_message,
 117                                         git_commit_encoding, encoding);
 118         if (out->reencoded_message)
 119                 out->message = out->reencoded_message;
 120
 121         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 122         abbrev_len = strlen(abbrev);
 123
 124         /* Find beginning and end of commit subject. */
 125         p = out->message;
 126         while (*p && (*p != '\n' || p[1] != '\n'))
 127                 p++;
 128         if (*p) {
 129                 p += 2;
 130                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 131                         ; /* do nothing */
 132         } else
 133                 eol = p;
 134         oneline_len = eol - p;
 135
 136         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 137                               strlen("... ") + oneline_len + 1);
 138         q = out->parent_label;
 139         q = mempcpy(q, "parent of ", strlen("parent of "));
 140         out->label = q;
 141         q = mempcpy(q, abbrev, abbrev_len);
 142         q = mempcpy(q, "... ", strlen("... "));
 143         out->subject = q;
 144         q = mempcpy(q, p, oneline_len);
 145         *q = '\0';
 146         return 0;
 147 }
 148
 149 static void free_message(struct commit_message *msg)
 150 {
 151         free(msg->parent_label);
 152         free(msg->reencoded_message);
 153 }
 154
 155 static char *get_encoding(const char *message)
 156 {
 157         const char *p = message, *eol;
 158
 159         if (!p)
 160                 die ("Could not read commit message of %s",
 161                                 sha1_to_hex(commit->object.sha1));
 162         while (*p && *p != '\n') {
 163                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 164                         ; /* do nothing */
 165                 if (!prefixcmp(p, "encoding ")) {
 166                         char *result = xmalloc(eol - 8 - p);
 167                         strlcpy(result, p + 9, eol - 8 - p);
 168                         return result;
 169                 }
 170                 p = eol;
 171                 if (*p == '\n')
 172                         p++;
 173         }
 174         return NULL;
 175 }
 176
 177 static struct lock_file msg_file;
 178 static int msg_fd;
 179
 180 static void add_to_msg(const char *string)
 181 {
 182         int len = strlen(string);
 183         if (write_in_full(msg_fd, string, len) < 0)
 184                 die_errno ("Could not write to MERGE_MSG");
 185 }
 186
 187 static void add_message_to_msg(const char *message)
 188 {
 189         const char *p = message;
 190         while (*p && (*p != '\n' || p[1] != '\n'))
 191                 p++;
 192
 193         if (!*p)
 194                 add_to_msg(sha1_to_hex(commit->object.sha1));
 195
 196         p += 2;
 197         add_to_msg(p);
 198         return;
 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 char *help_msg(const char *name)
 252 {
 253         struct strbuf helpbuf = STRBUF_INIT;
 254         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 255
 256         if (msg)
 257                 return msg;
 258
 259         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 260                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 261                 "and commit the result");
 262
 263         if (action == CHERRY_PICK) {
 264                 strbuf_addf(&helpbuf, " with: \n"
 265                         "\n"
 266                         "        git commit -c %s\n",
 267                         name);
 268         }
 269         else
 270                 strbuf_addch(&helpbuf, '.');
 271         return strbuf_detach(&helpbuf, NULL);
 272 }
 273
 274 static struct tree *empty_tree(void)
 275 {
 276         struct tree *tree = xcalloc(1, sizeof(struct tree));
 277
 278         tree->object.parsed = 1;
 279         tree->object.type = OBJ_TREE;
 280         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 281         return tree;
 282 }
 283
 284 static NORETURN void die_dirty_index(const char *me)
 285 {
 286         if (read_cache_unmerged()) {
 287                 die_resolve_conflict(me);
 288         } else {
 289                 if (advice_commit_before_merge)
 290                         die("Your local changes would be overwritten by %s.\n"
 291                             "Please, commit your changes or stash them to proceed.", me);
 292                 else
 293                         die("Your local changes would be overwritten by %s.\n", me);
 294         }
 295 }
 296
 297 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 298 {
 299         struct ref_lock *ref_lock;
 300
 301         read_cache();
 302         if (checkout_fast_forward(from, to))
 303                 exit(1); /* the callee should have complained already */
 304         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 305         return write_ref_sha1(ref_lock, to, "cherry-pick");
 306 }
 307
 308 static int revert_or_cherry_pick(int argc, const char **argv)
 309 {
 310         unsigned char head[20];
 311         struct commit *base, *next, *parent;
 312         const char *base_label, *next_label;
 313         int i, index_fd, clean;
 314         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 315         char *defmsg = NULL;
 316         struct merge_options o;
 317         struct tree *result, *next_tree, *base_tree, *head_tree;
 318         static struct lock_file index_lock;
 319
 320         git_config(git_default_config, NULL);
 321         me = action == REVERT ? "revert" : "cherry-pick";
 322         setenv(GIT_REFLOG_ACTION, me, 0);
 323         parse_args(argc, argv);
 324
 325         /* this is copied from the shell script, but it's never triggered... */
 326         if (action == REVERT && !no_replay)
 327                 die("revert is incompatible with replay");
 328
 329         if (allow_ff) {
 330                 if (signoff)
 331                         die("cherry-pick --ff cannot be used with --signoff");
 332                 if (no_commit)
 333                         die("cherry-pick --ff cannot be used with --no-commit");
 334                 if (no_replay)
 335                         die("cherry-pick --ff cannot be used with -x");
 336                 if (edit)
 337                         die("cherry-pick --ff cannot be used with --edit");
 338         }
 339
 340         if (read_cache() < 0)
 341                 die("git %s: failed to read the index", me);
 342         if (no_commit) {
 343                 /*
 344                  * We do not intend to commit immediately.  We just want to
 345                  * merge the differences in, so let's compute the tree
 346                  * that represents the "current" state for merge-recursive
 347                  * to work on.
 348                  */
 349                 if (write_cache_as_tree(head, 0, NULL))
 350                         die ("Your index file is unmerged.");
 351         } else {
 352                 if (get_sha1("HEAD", head))
 353                         die ("You do not have a valid HEAD");
 354                 if (index_differs_from("HEAD", 0))
 355                         die_dirty_index(me);
 356         }
 357         discard_cache();
 358
 359         if (!commit->parents) {
 360                 if (action == REVERT)
 361                         die ("Cannot revert a root commit");
 362                 parent = NULL;
 363         }
 364         else if (commit->parents->next) {
 365                 /* Reverting or cherry-picking a merge commit */
 366                 int cnt;
 367                 struct commit_list *p;
 368
 369                 if (!mainline)
 370                         die("Commit %s is a merge but no -m option was given.",
 371                             sha1_to_hex(commit->object.sha1));
 372
 373                 for (cnt = 1, p = commit->parents;
 374                      cnt != mainline && p;
 375                      cnt++)
 376                         p = p->next;
 377                 if (cnt != mainline || !p)
 378                         die("Commit %s does not have parent %d",
 379                             sha1_to_hex(commit->object.sha1), mainline);
 380                 parent = p->item;
 381         } else if (0 < mainline)
 382                 die("Mainline was specified but commit %s is not a merge.",
 383                     sha1_to_hex(commit->object.sha1));
 384         else
 385                 parent = commit->parents->item;
 386
 387         if (allow_ff && !hashcmp(parent->object.sha1, head))
 388                 return fast_forward_to(commit->object.sha1, head);
 389
 390         if (parent && parse_commit(parent) < 0)
 391                 die("%s: cannot parse parent commit %s",
 392                     me, sha1_to_hex(parent->object.sha1));
 393
 394         if (get_message(commit->buffer, &msg) != 0)
 395                 die("Cannot get commit message for %s",
 396                                 sha1_to_hex(commit->object.sha1));
 397
 398         /*
 399          * "commit" is an existing commit.  We would want to apply
 400          * the difference it introduces since its first parent "prev"
 401          * on top of the current HEAD if we are cherry-pick.  Or the
 402          * reverse of it if we are revert.
 403          */
 404
 405         defmsg = git_pathdup("MERGE_MSG");
 406         msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
 407                                            LOCK_DIE_ON_ERROR);
 408
 409         index_fd = hold_locked_index(&index_lock, 1);
 410
 411         if (action == REVERT) {
 412                 base = commit;
 413                 base_label = msg.label;
 414                 next = parent;
 415                 next_label = msg.parent_label;
 416                 add_to_msg("Revert \"");
 417                 add_to_msg(msg.subject);
 418                 add_to_msg("\"\n\nThis reverts commit ");
 419                 add_to_msg(sha1_to_hex(commit->object.sha1));
 420
 421                 if (commit->parents->next) {
 422                         add_to_msg(", reversing\nchanges made to ");
 423                         add_to_msg(sha1_to_hex(parent->object.sha1));
 424                 }
 425                 add_to_msg(".\n");
 426         } else {
 427                 base = parent;
 428                 base_label = msg.parent_label;
 429                 next = commit;
 430                 next_label = msg.label;
 431                 set_author_ident_env(msg.message);
 432                 add_message_to_msg(msg.message);
 433                 if (no_replay) {
 434                         add_to_msg("(cherry picked from commit ");
 435                         add_to_msg(sha1_to_hex(commit->object.sha1));
 436                         add_to_msg(")\n");
 437                 }
 438         }
 439
 440         read_cache();
 441         init_merge_options(&o);
 442         o.ancestor = base ? base_label : "(empty tree)";
 443         o.branch1 = "HEAD";
 444         o.branch2 = next ? next_label : "(empty tree)";
 445
 446         head_tree = parse_tree_indirect(head);
 447         next_tree = next ? next->tree : empty_tree();
 448         base_tree = base ? base->tree : empty_tree();
 449
 450         clean = merge_trees(&o,
 451                             head_tree,
 452                             next_tree, base_tree, &result);
 453
 454         if (active_cache_changed &&
 455             (write_cache(index_fd, active_cache, active_nr) ||
 456              commit_locked_index(&index_lock)))
 457                 die("%s: Unable to write new index file", me);
 458         rollback_lock_file(&index_lock);
 459
 460         if (!clean) {
 461                 add_to_msg("\nConflicts:\n\n");
 462                 for (i = 0; i < active_nr;) {
 463                         struct cache_entry *ce = active_cache[i++];
 464                         if (ce_stage(ce)) {
 465                                 add_to_msg("\t");
 466                                 add_to_msg(ce->name);
 467                                 add_to_msg("\n");
 468                                 while (i < active_nr && !strcmp(ce->name,
 469                                                 active_cache[i]->name))
 470                                         i++;
 471                         }
 472                 }
 473                 if (commit_lock_file(&msg_file) < 0)
 474                         die ("Error wrapping up %s", defmsg);
 475                 fprintf(stderr, "Automatic %s failed.%s\n",
 476                         me, help_msg(commit_name));
 477                 rerere(allow_rerere_auto);
 478                 exit(1);
 479         }
 480         if (commit_lock_file(&msg_file) < 0)
 481                 die ("Error wrapping up %s", defmsg);
 482         fprintf(stderr, "Finished one %s.\n", me);
 483
 484         /*
 485          *
 486          * If we are cherry-pick, and if the merge did not result in
 487          * hand-editing, we will hit this commit and inherit the original
 488          * author date and name.
 489          * If we are revert, or if our cherry-pick results in a hand merge,
 490          * we had better say that the current user is responsible for that.
 491          */
 492
 493         if (!no_commit) {
 494                 /* 6 is max possible length of our args array including NULL */
 495                 const char *args[6];
 496                 int i = 0;
 497                 args[i++] = "commit";
 498                 args[i++] = "-n";
 499                 if (signoff)
 500                         args[i++] = "-s";
 501                 if (!edit) {
 502                         args[i++] = "-F";
 503                         args[i++] = defmsg;
 504                 }
 505                 args[i] = NULL;
 506                 return execv_git_cmd(args);
 507         }
 508         free_message(&msg);
 509         free(defmsg);
 510
 511         return 0;
 512 }
 513
 514 int cmd_revert(int argc, const char **argv, const char *prefix)
 515 {
 516         if (isatty(0))
 517                 edit = 1;
 518         no_replay = 1;
 519         action = REVERT;
 520         return revert_or_cherry_pick(argc, argv);
 521 }
 522
 523 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 524 {
 525         no_replay = 0;
 526         action = CHERRY_PICK;
 527         return revert_or_cherry_pick(argc, argv);
 528 }