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         if ((out->reencoded_message = reencode_string(raw_message,
 113                                         git_commit_encoding, encoding)))
 114                 out->message = out->reencoded_message;
 115
 116         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 117         abbrev_len = strlen(abbrev);
 118
 119         /* Find beginning and end of commit subject. */
 120         p = out->message;
 121         while (*p && (*p != '\n' || p[1] != '\n'))
 122                 p++;
 123         if (*p) {
 124                 p += 2;
 125                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 126                         ; /* do nothing */
 127         } else
 128                 eol = p;
 129         oneline_len = eol - p;
 130
 131         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 132                               strlen("... ") + oneline_len + 1);
 133         q = out->parent_label;
 134         q = mempcpy(q, "parent of ", strlen("parent of "));
 135         out->label = q;
 136         q = mempcpy(q, abbrev, abbrev_len);
 137         q = mempcpy(q, "... ", strlen("... "));
 138         out->subject = q;
 139         q = mempcpy(q, p, oneline_len);
 140         *q = '\0';
 141         return 0;
 142 }
 143
 144 static void free_message(struct commit_message *msg)
 145 {
 146         free(msg->parent_label);
 147         free(msg->reencoded_message);
 148 }
 149
 150 static char *get_encoding(const char *message)
 151 {
 152         const char *p = message, *eol;
 153
 154         if (!p)
 155                 die ("Could not read commit message of %s",
 156                                 sha1_to_hex(commit->object.sha1));
 157         while (*p && *p != '\n') {
 158                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 159                         ; /* do nothing */
 160                 if (!prefixcmp(p, "encoding ")) {
 161                         char *result = xmalloc(eol - 8 - p);
 162                         strlcpy(result, p + 9, eol - 8 - p);
 163                         return result;
 164                 }
 165                 p = eol;
 166                 if (*p == '\n')
 167                         p++;
 168         }
 169         return NULL;
 170 }
 171
 172 static struct lock_file msg_file;
 173 static int msg_fd;
 174
 175 static void add_to_msg(const char *string)
 176 {
 177         int len = strlen(string);
 178         if (write_in_full(msg_fd, string, len) < 0)
 179                 die_errno ("Could not write to MERGE_MSG");
 180 }
 181
 182 static void add_message_to_msg(const char *message)
 183 {
 184         const char *p = message;
 185         while (*p && (*p != '\n' || p[1] != '\n'))
 186                 p++;
 187
 188         if (!*p)
 189                 add_to_msg(sha1_to_hex(commit->object.sha1));
 190
 191         p += 2;
 192         add_to_msg(p);
 193         return;
 194 }
 195
 196 static void set_author_ident_env(const char *message)
 197 {
 198         const char *p = message;
 199         if (!p)
 200                 die ("Could not read commit message of %s",
 201                                 sha1_to_hex(commit->object.sha1));
 202         while (*p && *p != '\n') {
 203                 const char *eol;
 204
 205                 for (eol = p; *eol && *eol != '\n'; eol++)
 206                         ; /* do nothing */
 207                 if (!prefixcmp(p, "author ")) {
 208                         char *line, *pend, *email, *timestamp;
 209
 210                         p += 7;
 211                         line = xmemdupz(p, eol - p);
 212                         email = strchr(line, '<');
 213                         if (!email)
 214                                 die ("Could not extract author email from %s",
 215                                         sha1_to_hex(commit->object.sha1));
 216                         if (email == line)
 217                                 pend = line;
 218                         else
 219                                 for (pend = email; pend != line + 1 &&
 220                                                 isspace(pend[-1]); pend--);
 221                                         ; /* do nothing */
 222                         *pend = '\0';
 223                         email++;
 224                         timestamp = strchr(email, '>');
 225                         if (!timestamp)
 226                                 die ("Could not extract author time from %s",
 227                                         sha1_to_hex(commit->object.sha1));
 228                         *timestamp = '\0';
 229                         for (timestamp++; *timestamp && isspace(*timestamp);
 230                                         timestamp++)
 231                                 ; /* do nothing */
 232                         setenv("GIT_AUTHOR_NAME", line, 1);
 233                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 234                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 235                         free(line);
 236                         return;
 237                 }
 238                 p = eol;
 239                 if (*p == '\n')
 240                         p++;
 241         }
 242         die ("No author information found in %s",
 243                         sha1_to_hex(commit->object.sha1));
 244 }
 245
 246 static char *help_msg(const char *name)
 247 {
 248         struct strbuf helpbuf = STRBUF_INIT;
 249         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 250
 251         if (msg)
 252                 return msg;
 253
 254         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 255                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 256                 "and commit the result");
 257
 258         if (action == CHERRY_PICK) {
 259                 strbuf_addf(&helpbuf, " with: \n"
 260                         "\n"
 261                         "        git commit -c %s\n",
 262                         name);
 263         }
 264         else
 265                 strbuf_addch(&helpbuf, '.');
 266         return strbuf_detach(&helpbuf, NULL);
 267 }
 268
 269 static struct tree *empty_tree(void)
 270 {
 271         struct tree *tree = xcalloc(1, sizeof(struct tree));
 272
 273         tree->object.parsed = 1;
 274         tree->object.type = OBJ_TREE;
 275         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 276         return tree;
 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 int revert_or_cherry_pick(int argc, const char **argv)
 304 {
 305         unsigned char head[20];
 306         struct commit *base, *next, *parent;
 307         const char *base_label, *next_label;
 308         int i, index_fd, clean;
 309         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 310         char *defmsg = NULL;
 311         struct merge_options o;
 312         struct tree *result, *next_tree, *base_tree, *head_tree;
 313         static struct lock_file index_lock;
 314
 315         git_config(git_default_config, NULL);
 316         me = action == REVERT ? "revert" : "cherry-pick";
 317         setenv(GIT_REFLOG_ACTION, me, 0);
 318         parse_args(argc, argv);
 319
 320         /* this is copied from the shell script, but it's never triggered... */
 321         if (action == REVERT && !no_replay)
 322                 die("revert is incompatible with replay");
 323
 324         if (allow_ff) {
 325                 if (signoff)
 326                         die("cherry-pick --ff cannot be used with --signoff");
 327                 if (no_commit)
 328                         die("cherry-pick --ff cannot be used with --no-commit");
 329                 if (no_replay)
 330                         die("cherry-pick --ff cannot be used with -x");
 331                 if (edit)
 332                         die("cherry-pick --ff cannot be used with --edit");
 333         }
 334
 335         if (read_cache() < 0)
 336                 die("git %s: failed to read the index", me);
 337         if (no_commit) {
 338                 /*
 339                  * We do not intend to commit immediately.  We just want to
 340                  * merge the differences in, so let's compute the tree
 341                  * that represents the "current" state for merge-recursive
 342                  * to work on.
 343                  */
 344                 if (write_cache_as_tree(head, 0, NULL))
 345                         die ("Your index file is unmerged.");
 346         } else {
 347                 if (get_sha1("HEAD", head))
 348                         die ("You do not have a valid HEAD");
 349                 if (index_differs_from("HEAD", 0))
 350                         die_dirty_index(me);
 351         }
 352         discard_cache();
 353
 354         if (!commit->parents) {
 355                 if (action == REVERT)
 356                         die ("Cannot revert a root commit");
 357                 parent = NULL;
 358         }
 359         else if (commit->parents->next) {
 360                 /* Reverting or cherry-picking a merge commit */
 361                 int cnt;
 362                 struct commit_list *p;
 363
 364                 if (!mainline)
 365                         die("Commit %s is a merge but no -m option was given.",
 366                             sha1_to_hex(commit->object.sha1));
 367
 368                 for (cnt = 1, p = commit->parents;
 369                      cnt != mainline && p;
 370                      cnt++)
 371                         p = p->next;
 372                 if (cnt != mainline || !p)
 373                         die("Commit %s does not have parent %d",
 374                             sha1_to_hex(commit->object.sha1), mainline);
 375                 parent = p->item;
 376         } else if (0 < mainline)
 377                 die("Mainline was specified but commit %s is not a merge.",
 378                     sha1_to_hex(commit->object.sha1));
 379         else
 380                 parent = commit->parents->item;
 381
 382         if (allow_ff && !hashcmp(parent->object.sha1, head))
 383                 return fast_forward_to(commit->object.sha1, head);
 384
 385         if (parent && parse_commit(parent) < 0)
 386                 die("%s: cannot parse parent commit %s",
 387                     me, sha1_to_hex(parent->object.sha1));
 388
 389         if (get_message(commit->buffer, &msg) != 0)
 390                 die("Cannot get commit message for %s",
 391                                 sha1_to_hex(commit->object.sha1));
 392
 393         /*
 394          * "commit" is an existing commit.  We would want to apply
 395          * the difference it introduces since its first parent "prev"
 396          * on top of the current HEAD if we are cherry-pick.  Or the
 397          * reverse of it if we are revert.
 398          */
 399
 400         defmsg = git_pathdup("MERGE_MSG");
 401         msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
 402                                            LOCK_DIE_ON_ERROR);
 403
 404         index_fd = hold_locked_index(&index_lock, 1);
 405
 406         if (action == REVERT) {
 407                 base = commit;
 408                 base_label = msg.label;
 409                 next = parent;
 410                 next_label = msg.parent_label;
 411                 add_to_msg("Revert \"");
 412                 add_to_msg(msg.subject);
 413                 add_to_msg("\"\n\nThis reverts commit ");
 414                 add_to_msg(sha1_to_hex(commit->object.sha1));
 415
 416                 if (commit->parents->next) {
 417                         add_to_msg(", reversing\nchanges made to ");
 418                         add_to_msg(sha1_to_hex(parent->object.sha1));
 419                 }
 420                 add_to_msg(".\n");
 421         } else {
 422                 base = parent;
 423                 base_label = msg.parent_label;
 424                 next = commit;
 425                 next_label = msg.label;
 426                 set_author_ident_env(msg.message);
 427                 add_message_to_msg(msg.message);
 428                 if (no_replay) {
 429                         add_to_msg("(cherry picked from commit ");
 430                         add_to_msg(sha1_to_hex(commit->object.sha1));
 431                         add_to_msg(")\n");
 432                 }
 433         }
 434
 435         read_cache();
 436         init_merge_options(&o);
 437         o.ancestor = base ? base_label : "(empty tree)";
 438         o.branch1 = "HEAD";
 439         o.branch2 = next ? next_label : "(empty tree)";
 440
 441         head_tree = parse_tree_indirect(head);
 442         next_tree = next ? next->tree : empty_tree();
 443         base_tree = base ? base->tree : empty_tree();
 444
 445         clean = merge_trees(&o,
 446                             head_tree,
 447                             next_tree, base_tree, &result);
 448
 449         if (active_cache_changed &&
 450             (write_cache(index_fd, active_cache, active_nr) ||
 451              commit_locked_index(&index_lock)))
 452                 die("%s: Unable to write new index file", me);
 453         rollback_lock_file(&index_lock);
 454
 455         if (!clean) {
 456                 add_to_msg("\nConflicts:\n\n");
 457                 for (i = 0; i < active_nr;) {
 458                         struct cache_entry *ce = active_cache[i++];
 459                         if (ce_stage(ce)) {
 460                                 add_to_msg("\t");
 461                                 add_to_msg(ce->name);
 462                                 add_to_msg("\n");
 463                                 while (i < active_nr && !strcmp(ce->name,
 464                                                 active_cache[i]->name))
 465                                         i++;
 466                         }
 467                 }
 468                 if (commit_lock_file(&msg_file) < 0)
 469                         die ("Error wrapping up %s", defmsg);
 470                 fprintf(stderr, "Automatic %s failed.%s\n",
 471                         me, help_msg(commit_name));
 472                 rerere(allow_rerere_auto);
 473                 exit(1);
 474         }
 475         if (commit_lock_file(&msg_file) < 0)
 476                 die ("Error wrapping up %s", defmsg);
 477         fprintf(stderr, "Finished one %s.\n", me);
 478
 479         /*
 480          *
 481          * If we are cherry-pick, and if the merge did not result in
 482          * hand-editing, we will hit this commit and inherit the original
 483          * author date and name.
 484          * If we are revert, or if our cherry-pick results in a hand merge,
 485          * we had better say that the current user is responsible for that.
 486          */
 487
 488         if (!no_commit) {
 489                 /* 6 is max possible length of our args array including NULL */
 490                 const char *args[6];
 491                 int i = 0;
 492                 args[i++] = "commit";
 493                 args[i++] = "-n";
 494                 if (signoff)
 495                         args[i++] = "-s";
 496                 if (!edit) {
 497                         args[i++] = "-F";
 498                         args[i++] = defmsg;
 499                 }
 500                 args[i] = NULL;
 501                 return execv_git_cmd(args);
 502         }
 503         free_message(&msg);
 504         free(defmsg);
 505
 506         return 0;
 507 }
 508
 509 int cmd_revert(int argc, const char **argv, const char *prefix)
 510 {
 511         if (isatty(0))
 512                 edit = 1;
 513         no_replay = 1;
 514         action = REVERT;
 515         return revert_or_cherry_pick(argc, argv);
 516 }
 517
 518 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 519 {
 520         no_replay = 0;
 521         action = CHERRY_PICK;
 522         return revert_or_cherry_pick(argc, argv);
 523 }