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 *abbrev, *subject;
 102         int abbrev_len, subject_len;
 103         char *q;
 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         subject_len = find_commit_subject(out->message, &subject);
 125
 126         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 127                               strlen("... ") + subject_len + 1);
 128         q = out->parent_label;
 129         q = mempcpy(q, "parent of ", strlen("parent of "));
 130         out->label = q;
 131         q = mempcpy(q, abbrev, abbrev_len);
 132         q = mempcpy(q, "... ", strlen("... "));
 133         out->subject = q;
 134         q = mempcpy(q, subject, subject_len);
 135         *q = '\0';
 136         return 0;
 137 }
 138
 139 static void free_message(struct commit_message *msg)
 140 {
 141         free(msg->parent_label);
 142         free(msg->reencoded_message);
 143 }
 144
 145 static char *get_encoding(const char *message)
 146 {
 147         const char *p = message, *eol;
 148
 149         if (!p)
 150                 die ("Could not read commit message of %s",
 151                                 sha1_to_hex(commit->object.sha1));
 152         while (*p && *p != '\n') {
 153                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 154                         ; /* do nothing */
 155                 if (!prefixcmp(p, "encoding ")) {
 156                         char *result = xmalloc(eol - 8 - p);
 157                         strlcpy(result, p + 9, eol - 8 - p);
 158                         return result;
 159                 }
 160                 p = eol;
 161                 if (*p == '\n')
 162                         p++;
 163         }
 164         return NULL;
 165 }
 166
 167 static struct lock_file msg_file;
 168 static int msg_fd;
 169
 170 static void add_to_msg(const char *string)
 171 {
 172         int len = strlen(string);
 173         if (write_in_full(msg_fd, string, len) < 0)
 174                 die_errno ("Could not write to MERGE_MSG");
 175 }
 176
 177 static void add_message_to_msg(const char *message)
 178 {
 179         const char *p = message;
 180         while (*p && (*p != '\n' || p[1] != '\n'))
 181                 p++;
 182
 183         if (!*p)
 184                 add_to_msg(sha1_to_hex(commit->object.sha1));
 185
 186         p += 2;
 187         add_to_msg(p);
 188         return;
 189 }
 190
 191 static void set_author_ident_env(const char *message)
 192 {
 193         const char *p = message;
 194         if (!p)
 195                 die ("Could not read commit message of %s",
 196                                 sha1_to_hex(commit->object.sha1));
 197         while (*p && *p != '\n') {
 198                 const char *eol;
 199
 200                 for (eol = p; *eol && *eol != '\n'; eol++)
 201                         ; /* do nothing */
 202                 if (!prefixcmp(p, "author ")) {
 203                         char *line, *pend, *email, *timestamp;
 204
 205                         p += 7;
 206                         line = xmemdupz(p, eol - p);
 207                         email = strchr(line, '<');
 208                         if (!email)
 209                                 die ("Could not extract author email from %s",
 210                                         sha1_to_hex(commit->object.sha1));
 211                         if (email == line)
 212                                 pend = line;
 213                         else
 214                                 for (pend = email; pend != line + 1 &&
 215                                                 isspace(pend[-1]); pend--);
 216                                         ; /* do nothing */
 217                         *pend = '\0';
 218                         email++;
 219                         timestamp = strchr(email, '>');
 220                         if (!timestamp)
 221                                 die ("Could not extract author time from %s",
 222                                         sha1_to_hex(commit->object.sha1));
 223                         *timestamp = '\0';
 224                         for (timestamp++; *timestamp && isspace(*timestamp);
 225                                         timestamp++)
 226                                 ; /* do nothing */
 227                         setenv("GIT_AUTHOR_NAME", line, 1);
 228                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 229                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 230                         free(line);
 231                         return;
 232                 }
 233                 p = eol;
 234                 if (*p == '\n')
 235                         p++;
 236         }
 237         die ("No author information found in %s",
 238                         sha1_to_hex(commit->object.sha1));
 239 }
 240
 241 static char *help_msg(const char *name)
 242 {
 243         struct strbuf helpbuf = STRBUF_INIT;
 244         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 245
 246         if (msg)
 247                 return msg;
 248
 249         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 250                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 251                 "and commit the result");
 252
 253         if (action == CHERRY_PICK) {
 254                 strbuf_addf(&helpbuf, " with: \n"
 255                         "\n"
 256                         "        git commit -c %s\n",
 257                         name);
 258         }
 259         else
 260                 strbuf_addch(&helpbuf, '.');
 261         return strbuf_detach(&helpbuf, NULL);
 262 }
 263
 264 static struct tree *empty_tree(void)
 265 {
 266         struct tree *tree = xcalloc(1, sizeof(struct tree));
 267
 268         tree->object.parsed = 1;
 269         tree->object.type = OBJ_TREE;
 270         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 271         return tree;
 272 }
 273
 274 static NORETURN void die_dirty_index(const char *me)
 275 {
 276         if (read_cache_unmerged()) {
 277                 die_resolve_conflict(me);
 278         } else {
 279                 if (advice_commit_before_merge)
 280                         die("Your local changes would be overwritten by %s.\n"
 281                             "Please, commit your changes or stash them to proceed.", me);
 282                 else
 283                         die("Your local changes would be overwritten by %s.\n", me);
 284         }
 285 }
 286
 287 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 288 {
 289         struct ref_lock *ref_lock;
 290
 291         read_cache();
 292         if (checkout_fast_forward(from, to))
 293                 exit(1); /* the callee should have complained already */
 294         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 295         return write_ref_sha1(ref_lock, to, "cherry-pick");
 296 }
 297
 298 static int revert_or_cherry_pick(int argc, const char **argv)
 299 {
 300         unsigned char head[20];
 301         struct commit *base, *next, *parent;
 302         const char *base_label, *next_label;
 303         int i, index_fd, clean;
 304         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 305         char *defmsg = NULL;
 306         struct merge_options o;
 307         struct tree *result, *next_tree, *base_tree, *head_tree;
 308         static struct lock_file index_lock;
 309
 310         git_config(git_default_config, NULL);
 311         me = action == REVERT ? "revert" : "cherry-pick";
 312         setenv(GIT_REFLOG_ACTION, me, 0);
 313         parse_args(argc, argv);
 314
 315         /* this is copied from the shell script, but it's never triggered... */
 316         if (action == REVERT && !no_replay)
 317                 die("revert is incompatible with replay");
 318
 319         if (allow_ff) {
 320                 if (signoff)
 321                         die("cherry-pick --ff cannot be used with --signoff");
 322                 if (no_commit)
 323                         die("cherry-pick --ff cannot be used with --no-commit");
 324                 if (no_replay)
 325                         die("cherry-pick --ff cannot be used with -x");
 326                 if (edit)
 327                         die("cherry-pick --ff cannot be used with --edit");
 328         }
 329
 330         if (read_cache() < 0)
 331                 die("git %s: failed to read the index", me);
 332         if (no_commit) {
 333                 /*
 334                  * We do not intend to commit immediately.  We just want to
 335                  * merge the differences in, so let's compute the tree
 336                  * that represents the "current" state for merge-recursive
 337                  * to work on.
 338                  */
 339                 if (write_cache_as_tree(head, 0, NULL))
 340                         die ("Your index file is unmerged.");
 341         } else {
 342                 if (get_sha1("HEAD", head))
 343                         die ("You do not have a valid HEAD");
 344                 if (index_differs_from("HEAD", 0))
 345                         die_dirty_index(me);
 346         }
 347         discard_cache();
 348
 349         if (!commit->parents) {
 350                 if (action == REVERT)
 351                         die ("Cannot revert a root commit");
 352                 parent = NULL;
 353         }
 354         else if (commit->parents->next) {
 355                 /* Reverting or cherry-picking a merge commit */
 356                 int cnt;
 357                 struct commit_list *p;
 358
 359                 if (!mainline)
 360                         die("Commit %s is a merge but no -m option was given.",
 361                             sha1_to_hex(commit->object.sha1));
 362
 363                 for (cnt = 1, p = commit->parents;
 364                      cnt != mainline && p;
 365                      cnt++)
 366                         p = p->next;
 367                 if (cnt != mainline || !p)
 368                         die("Commit %s does not have parent %d",
 369                             sha1_to_hex(commit->object.sha1), mainline);
 370                 parent = p->item;
 371         } else if (0 < mainline)
 372                 die("Mainline was specified but commit %s is not a merge.",
 373                     sha1_to_hex(commit->object.sha1));
 374         else
 375                 parent = commit->parents->item;
 376
 377         if (allow_ff && !hashcmp(parent->object.sha1, head))
 378                 return fast_forward_to(commit->object.sha1, head);
 379
 380         if (parent && parse_commit(parent) < 0)
 381                 die("%s: cannot parse parent commit %s",
 382                     me, sha1_to_hex(parent->object.sha1));
 383
 384         if (get_message(commit->buffer, &msg) != 0)
 385                 die("Cannot get commit message for %s",
 386                                 sha1_to_hex(commit->object.sha1));
 387
 388         /*
 389          * "commit" is an existing commit.  We would want to apply
 390          * the difference it introduces since its first parent "prev"
 391          * on top of the current HEAD if we are cherry-pick.  Or the
 392          * reverse of it if we are revert.
 393          */
 394
 395         defmsg = git_pathdup("MERGE_MSG");
 396         msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
 397                                            LOCK_DIE_ON_ERROR);
 398
 399         index_fd = hold_locked_index(&index_lock, 1);
 400
 401         if (action == REVERT) {
 402                 base = commit;
 403                 base_label = msg.label;
 404                 next = parent;
 405                 next_label = msg.parent_label;
 406                 add_to_msg("Revert \"");
 407                 add_to_msg(msg.subject);
 408                 add_to_msg("\"\n\nThis reverts commit ");
 409                 add_to_msg(sha1_to_hex(commit->object.sha1));
 410
 411                 if (commit->parents->next) {
 412                         add_to_msg(", reversing\nchanges made to ");
 413                         add_to_msg(sha1_to_hex(parent->object.sha1));
 414                 }
 415                 add_to_msg(".\n");
 416         } else {
 417                 base = parent;
 418                 base_label = msg.parent_label;
 419                 next = commit;
 420                 next_label = msg.label;
 421                 set_author_ident_env(msg.message);
 422                 add_message_to_msg(msg.message);
 423                 if (no_replay) {
 424                         add_to_msg("(cherry picked from commit ");
 425                         add_to_msg(sha1_to_hex(commit->object.sha1));
 426                         add_to_msg(")\n");
 427                 }
 428         }
 429
 430         read_cache();
 431         init_merge_options(&o);
 432         o.ancestor = base ? base_label : "(empty tree)";
 433         o.branch1 = "HEAD";
 434         o.branch2 = next ? next_label : "(empty tree)";
 435
 436         head_tree = parse_tree_indirect(head);
 437         next_tree = next ? next->tree : empty_tree();
 438         base_tree = base ? base->tree : empty_tree();
 439
 440         clean = merge_trees(&o,
 441                             head_tree,
 442                             next_tree, base_tree, &result);
 443
 444         if (active_cache_changed &&
 445             (write_cache(index_fd, active_cache, active_nr) ||
 446              commit_locked_index(&index_lock)))
 447                 die("%s: Unable to write new index file", me);
 448         rollback_lock_file(&index_lock);
 449
 450         if (!clean) {
 451                 add_to_msg("\nConflicts:\n\n");
 452                 for (i = 0; i < active_nr;) {
 453                         struct cache_entry *ce = active_cache[i++];
 454                         if (ce_stage(ce)) {
 455                                 add_to_msg("\t");
 456                                 add_to_msg(ce->name);
 457                                 add_to_msg("\n");
 458                                 while (i < active_nr && !strcmp(ce->name,
 459                                                 active_cache[i]->name))
 460                                         i++;
 461                         }
 462                 }
 463                 if (commit_lock_file(&msg_file) < 0)
 464                         die ("Error wrapping up %s", defmsg);
 465                 fprintf(stderr, "Automatic %s failed.%s\n",
 466                         me, help_msg(commit_name));
 467                 rerere(allow_rerere_auto);
 468                 exit(1);
 469         }
 470         if (commit_lock_file(&msg_file) < 0)
 471                 die ("Error wrapping up %s", defmsg);
 472         fprintf(stderr, "Finished one %s.\n", me);
 473
 474         /*
 475          *
 476          * If we are cherry-pick, and if the merge did not result in
 477          * hand-editing, we will hit this commit and inherit the original
 478          * author date and name.
 479          * If we are revert, or if our cherry-pick results in a hand merge,
 480          * we had better say that the current user is responsible for that.
 481          */
 482
 483         if (!no_commit) {
 484                 /* 6 is max possible length of our args array including NULL */
 485                 const char *args[6];
 486                 int i = 0;
 487                 args[i++] = "commit";
 488                 args[i++] = "-n";
 489                 if (signoff)
 490                         args[i++] = "-s";
 491                 if (!edit) {
 492                         args[i++] = "-F";
 493                         args[i++] = defmsg;
 494                 }
 495                 args[i] = NULL;
 496                 return execv_git_cmd(args);
 497         }
 498         free_message(&msg);
 499         free(defmsg);
 500
 501         return 0;
 502 }
 503
 504 int cmd_revert(int argc, const char **argv, const char *prefix)
 505 {
 506         if (isatty(0))
 507                 edit = 1;
 508         no_replay = 1;
 509         action = REVERT;
 510         return revert_or_cherry_pick(argc, argv);
 511 }
 512
 513 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 514 {
 515         no_replay = 0;
 516         action = CHERRY_PICK;
 517         return revert_or_cherry_pick(argc, argv);
 518 }