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
  17 /*
  18  * This implements the builtins revert and cherry-pick.
  19  *
  20  * Copyright (c) 2007 Johannes E. Schindelin
  21  *
  22  * Based on git-revert.sh, which is
  23  *
  24  * Copyright (c) 2005 Linus Torvalds
  25  * Copyright (c) 2005 Junio C Hamano
  26  */
  27
  28 static const char * const revert_usage[] = {
  29         "git revert [options] <commit-ish>",
  30         NULL
  31 };
  32
  33 static const char * const cherry_pick_usage[] = {
  34         "git cherry-pick [options] <commit-ish>",
  35         NULL
  36 };
  37
  38 static int edit, no_replay, no_commit, mainline, signoff;
  39 static enum { REVERT, CHERRY_PICK } action;
  40 static struct commit *commit;
  41 static const char *commit_name;
  42 static int allow_rerere_auto;
  43
  44 static const char *me;
  45
  46 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  47
  48 static char *get_encoding(const char *message);
  49
  50 static void parse_args(int argc, const char **argv)
  51 {
  52         const char * const * usage_str =
  53                 action == REVERT ?  revert_usage : cherry_pick_usage;
  54         unsigned char sha1[20];
  55         int noop;
  56         struct option options[] = {
  57                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
  58                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
  59                 OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
  60                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
  61                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
  62                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
  63                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
  64                 OPT_END(),
  65         };
  66
  67         if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
  68                 usage_with_options(usage_str, options);
  69
  70         commit_name = argv[0];
  71         if (get_sha1(commit_name, sha1))
  72                 die ("Cannot find '%s'", commit_name);
  73         commit = lookup_commit_reference(sha1);
  74         if (!commit)
  75                 exit(1);
  76 }
  77
  78 struct commit_message {
  79         char *parent_label;
  80         const char *label;
  81         const char *subject;
  82         char *reencoded_message;
  83         const char *message;
  84 };
  85
  86 static int get_message(const char *raw_message, struct commit_message *out)
  87 {
  88         const char *encoding;
  89         const char *p, *abbrev, *eol;
  90         char *q;
  91         int abbrev_len, oneline_len;
  92
  93         if (!raw_message)
  94                 return -1;
  95         encoding = get_encoding(raw_message);
  96         if (!encoding)
  97                 encoding = "UTF-8";
  98         if (!git_commit_encoding)
  99                 git_commit_encoding = "UTF-8";
 100         if ((out->reencoded_message = reencode_string(raw_message,
 101                                         git_commit_encoding, encoding)))
 102                 out->message = out->reencoded_message;
 103
 104         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 105         abbrev_len = strlen(abbrev);
 106
 107         /* Find beginning and end of commit subject. */
 108         p = out->message;
 109         while (*p && (*p != '\n' || p[1] != '\n'))
 110                 p++;
 111         if (*p) {
 112                 p += 2;
 113                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 114                         ; /* do nothing */
 115         } else
 116                 eol = p;
 117         oneline_len = eol - p;
 118
 119         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 120                               strlen("... ") + oneline_len + 1);
 121         q = out->parent_label;
 122         q = mempcpy(q, "parent of ", strlen("parent of "));
 123         out->label = q;
 124         q = mempcpy(q, abbrev, abbrev_len);
 125         q = mempcpy(q, "... ", strlen("... "));
 126         out->subject = q;
 127         q = mempcpy(q, p, oneline_len);
 128         *q = '\0';
 129         return 0;
 130 }
 131
 132 static void free_message(struct commit_message *msg)
 133 {
 134         free(msg->parent_label);
 135         free(msg->reencoded_message);
 136 }
 137
 138 static char *get_encoding(const char *message)
 139 {
 140         const char *p = message, *eol;
 141
 142         if (!p)
 143                 die ("Could not read commit message of %s",
 144                                 sha1_to_hex(commit->object.sha1));
 145         while (*p && *p != '\n') {
 146                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 147                         ; /* do nothing */
 148                 if (!prefixcmp(p, "encoding ")) {
 149                         char *result = xmalloc(eol - 8 - p);
 150                         strlcpy(result, p + 9, eol - 8 - p);
 151                         return result;
 152                 }
 153                 p = eol;
 154                 if (*p == '\n')
 155                         p++;
 156         }
 157         return NULL;
 158 }
 159
 160 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 161 {
 162         const char *p = message;
 163         while (*p && (*p != '\n' || p[1] != '\n'))
 164                 p++;
 165
 166         if (!*p)
 167                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 168
 169         p += 2;
 170         strbuf_addstr(msgbuf, p);
 171 }
 172
 173 static void set_author_ident_env(const char *message)
 174 {
 175         const char *p = message;
 176         if (!p)
 177                 die ("Could not read commit message of %s",
 178                                 sha1_to_hex(commit->object.sha1));
 179         while (*p && *p != '\n') {
 180                 const char *eol;
 181
 182                 for (eol = p; *eol && *eol != '\n'; eol++)
 183                         ; /* do nothing */
 184                 if (!prefixcmp(p, "author ")) {
 185                         char *line, *pend, *email, *timestamp;
 186
 187                         p += 7;
 188                         line = xmemdupz(p, eol - p);
 189                         email = strchr(line, '<');
 190                         if (!email)
 191                                 die ("Could not extract author email from %s",
 192                                         sha1_to_hex(commit->object.sha1));
 193                         if (email == line)
 194                                 pend = line;
 195                         else
 196                                 for (pend = email; pend != line + 1 &&
 197                                                 isspace(pend[-1]); pend--);
 198                                         ; /* do nothing */
 199                         *pend = '\0';
 200                         email++;
 201                         timestamp = strchr(email, '>');
 202                         if (!timestamp)
 203                                 die ("Could not extract author time from %s",
 204                                         sha1_to_hex(commit->object.sha1));
 205                         *timestamp = '\0';
 206                         for (timestamp++; *timestamp && isspace(*timestamp);
 207                                         timestamp++)
 208                                 ; /* do nothing */
 209                         setenv("GIT_AUTHOR_NAME", line, 1);
 210                         setenv("GIT_AUTHOR_EMAIL", email, 1);
 211                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
 212                         free(line);
 213                         return;
 214                 }
 215                 p = eol;
 216                 if (*p == '\n')
 217                         p++;
 218         }
 219         die ("No author information found in %s",
 220                         sha1_to_hex(commit->object.sha1));
 221 }
 222
 223 static char *help_msg(const char *name)
 224 {
 225         struct strbuf helpbuf = STRBUF_INIT;
 226         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 227
 228         if (msg)
 229                 return msg;
 230
 231         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
 232                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
 233                 "and commit the result");
 234
 235         if (action == CHERRY_PICK) {
 236                 strbuf_addf(&helpbuf, " with: \n"
 237                         "\n"
 238                         "        git commit -c %s\n",
 239                         name);
 240         }
 241         else
 242                 strbuf_addch(&helpbuf, '.');
 243         return strbuf_detach(&helpbuf, NULL);
 244 }
 245
 246 static void write_message(struct strbuf *msgbuf, const char *filename)
 247 {
 248         static struct lock_file msg_file;
 249
 250         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 251                                                LOCK_DIE_ON_ERROR);
 252         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 253                 die_errno("Could not write to %s.", filename);
 254         strbuf_release(msgbuf);
 255         if (commit_lock_file(&msg_file) < 0)
 256                 die("Error wrapping up %s", filename);
 257 }
 258
 259 static struct tree *empty_tree(void)
 260 {
 261         struct tree *tree = xcalloc(1, sizeof(struct tree));
 262
 263         tree->object.parsed = 1;
 264         tree->object.type = OBJ_TREE;
 265         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 266         return tree;
 267 }
 268
 269 static NORETURN void die_dirty_index(const char *me)
 270 {
 271         if (read_cache_unmerged()) {
 272                 die_resolve_conflict(me);
 273         } else {
 274                 if (advice_commit_before_merge)
 275                         die("Your local changes would be overwritten by %s.\n"
 276                             "Please, commit your changes or stash them to proceed.", me);
 277                 else
 278                         die("Your local changes would be overwritten by %s.\n", me);
 279         }
 280 }
 281
 282 static int revert_or_cherry_pick(int argc, const char **argv)
 283 {
 284         unsigned char head[20];
 285         struct commit *base, *next, *parent;
 286         const char *base_label, *next_label;
 287         int i, index_fd, clean;
 288         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 289
 290         char *defmsg = git_pathdup("MERGE_MSG");
 291         struct merge_options o;
 292         struct tree *result, *next_tree, *base_tree, *head_tree;
 293         static struct lock_file index_lock;
 294         struct strbuf msgbuf = STRBUF_INIT;
 295
 296         git_config(git_default_config, NULL);
 297         me = action == REVERT ? "revert" : "cherry-pick";
 298         setenv(GIT_REFLOG_ACTION, me, 0);
 299         parse_args(argc, argv);
 300
 301         /* this is copied from the shell script, but it's never triggered... */
 302         if (action == REVERT && !no_replay)
 303                 die("revert is incompatible with replay");
 304
 305         if (read_cache() < 0)
 306                 die("git %s: failed to read the index", me);
 307         if (no_commit) {
 308                 /*
 309                  * We do not intend to commit immediately.  We just want to
 310                  * merge the differences in, so let's compute the tree
 311                  * that represents the "current" state for merge-recursive
 312                  * to work on.
 313                  */
 314                 if (write_cache_as_tree(head, 0, NULL))
 315                         die ("Your index file is unmerged.");
 316         } else {
 317                 if (get_sha1("HEAD", head))
 318                         die ("You do not have a valid HEAD");
 319                 if (index_differs_from("HEAD", 0))
 320                         die_dirty_index(me);
 321         }
 322         discard_cache();
 323
 324         index_fd = hold_locked_index(&index_lock, 1);
 325
 326         if (!commit->parents) {
 327                 if (action == REVERT)
 328                         die ("Cannot revert a root commit");
 329                 parent = NULL;
 330         }
 331         else if (commit->parents->next) {
 332                 /* Reverting or cherry-picking a merge commit */
 333                 int cnt;
 334                 struct commit_list *p;
 335
 336                 if (!mainline)
 337                         die("Commit %s is a merge but no -m option was given.",
 338                             sha1_to_hex(commit->object.sha1));
 339
 340                 for (cnt = 1, p = commit->parents;
 341                      cnt != mainline && p;
 342                      cnt++)
 343                         p = p->next;
 344                 if (cnt != mainline || !p)
 345                         die("Commit %s does not have parent %d",
 346                             sha1_to_hex(commit->object.sha1), mainline);
 347                 parent = p->item;
 348         } else if (0 < mainline)
 349                 die("Mainline was specified but commit %s is not a merge.",
 350                     sha1_to_hex(commit->object.sha1));
 351         else
 352                 parent = commit->parents->item;
 353
 354         if (parent && parse_commit(parent) < 0)
 355                 die("%s: cannot parse parent commit %s",
 356                     me, sha1_to_hex(parent->object.sha1));
 357
 358         if (get_message(commit->buffer, &msg) != 0)
 359                 die("Cannot get commit message for %s",
 360                                 sha1_to_hex(commit->object.sha1));
 361
 362         /*
 363          * "commit" is an existing commit.  We would want to apply
 364          * the difference it introduces since its first parent "prev"
 365          * on top of the current HEAD if we are cherry-pick.  Or the
 366          * reverse of it if we are revert.
 367          */
 368
 369         if (action == REVERT) {
 370                 base = commit;
 371                 base_label = msg.label;
 372                 next = parent;
 373                 next_label = msg.parent_label;
 374                 strbuf_addstr(&msgbuf, "Revert \"");
 375                 strbuf_addstr(&msgbuf, msg.subject);
 376                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 377                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 378
 379                 if (commit->parents->next) {
 380                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 381                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 382                 }
 383                 strbuf_addstr(&msgbuf, ".\n");
 384         } else {
 385                 base = parent;
 386                 base_label = msg.parent_label;
 387                 next = commit;
 388                 next_label = msg.label;
 389                 set_author_ident_env(msg.message);
 390                 add_message_to_msg(&msgbuf, msg.message);
 391                 if (no_replay) {
 392                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 393                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 394                         strbuf_addstr(&msgbuf, ")\n");
 395                 }
 396         }
 397
 398         read_cache();
 399         init_merge_options(&o);
 400         o.ancestor = base ? base_label : "(empty tree)";
 401         o.branch1 = "HEAD";
 402         o.branch2 = next ? next_label : "(empty tree)";
 403
 404         head_tree = parse_tree_indirect(head);
 405         next_tree = next ? next->tree : empty_tree();
 406         base_tree = base ? base->tree : empty_tree();
 407
 408         clean = merge_trees(&o,
 409                             head_tree,
 410                             next_tree, base_tree, &result);
 411
 412         if (active_cache_changed &&
 413             (write_cache(index_fd, active_cache, active_nr) ||
 414              commit_locked_index(&index_lock)))
 415                 die("%s: Unable to write new index file", me);
 416         rollback_lock_file(&index_lock);
 417
 418         if (!clean) {
 419                 strbuf_addstr(&msgbuf, "\nConflicts:\n\n");
 420                 for (i = 0; i < active_nr;) {
 421                         struct cache_entry *ce = active_cache[i++];
 422                         if (ce_stage(ce)) {
 423                                 strbuf_addch(&msgbuf, '\t');
 424                                 strbuf_addstr(&msgbuf, ce->name);
 425                                 strbuf_addch(&msgbuf, '\n');
 426                                 while (i < active_nr && !strcmp(ce->name,
 427                                                 active_cache[i]->name))
 428                                         i++;
 429                         }
 430                 }
 431                 write_message(&msgbuf, defmsg);
 432                 fprintf(stderr, "Automatic %s failed.%s\n",
 433                         me, help_msg(commit_name));
 434                 rerere(allow_rerere_auto);
 435                 exit(1);
 436         }
 437         write_message(&msgbuf, defmsg);
 438         fprintf(stderr, "Finished one %s.\n", me);
 439
 440         /*
 441          *
 442          * If we are cherry-pick, and if the merge did not result in
 443          * hand-editing, we will hit this commit and inherit the original
 444          * author date and name.
 445          * If we are revert, or if our cherry-pick results in a hand merge,
 446          * we had better say that the current user is responsible for that.
 447          */
 448
 449         if (!no_commit) {
 450                 /* 6 is max possible length of our args array including NULL */
 451                 const char *args[6];
 452                 int i = 0;
 453                 args[i++] = "commit";
 454                 args[i++] = "-n";
 455                 if (signoff)
 456                         args[i++] = "-s";
 457                 if (!edit) {
 458                         args[i++] = "-F";
 459                         args[i++] = defmsg;
 460                 }
 461                 args[i] = NULL;
 462                 return execv_git_cmd(args);
 463         }
 464         free_message(&msg);
 465         free(defmsg);
 466
 467         return 0;
 468 }
 469
 470 int cmd_revert(int argc, const char **argv, const char *prefix)
 471 {
 472         if (isatty(0))
 473                 edit = 1;
 474         no_replay = 1;
 475         action = REVERT;
 476         return revert_or_cherry_pick(argc, argv);
 477 }
 478
 479 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 480 {
 481         no_replay = 0;
 482         action = CHERRY_PICK;
 483         return revert_or_cherry_pick(argc, argv);
 484 }