sequencer.c

   1 #include "cache.h"
   2 #include "sequencer.h"
   3 #include "dir.h"
   4 #include "object.h"
   5 #include "commit.h"
   6 #include "tag.h"
   7 #include "run-command.h"
   8 #include "exec_cmd.h"
   9 #include "utf8.h"
  10 #include "cache-tree.h"
  11 #include "diff.h"
  12 #include "revision.h"
  13 #include "rerere.h"
  14 #include "merge-recursive.h"
  15 #include "refs.h"
  16
  17 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  18
  19 void remove_sequencer_state(void)
  20 {
  21         struct strbuf seq_dir = STRBUF_INIT;
  22
  23         strbuf_addf(&seq_dir, "%s", git_path(SEQ_DIR));
  24         remove_dir_recursively(&seq_dir, 0);
  25         strbuf_release(&seq_dir);
  26 }
  27
  28 static const char *action_name(const struct replay_opts *opts)
  29 {
  30         return opts->action == REPLAY_REVERT ? "revert" : "cherry-pick";
  31 }
  32
  33 static char *get_encoding(const char *message);
  34
  35 struct commit_message {
  36         char *parent_label;
  37         const char *label;
  38         const char *subject;
  39         char *reencoded_message;
  40         const char *message;
  41 };
  42
  43 static int get_message(struct commit *commit, struct commit_message *out)
  44 {
  45         const char *encoding;
  46         const char *abbrev, *subject;
  47         int abbrev_len, subject_len;
  48         char *q;
  49
  50         if (!commit->buffer)
  51                 return -1;
  52         encoding = get_encoding(commit->buffer);
  53         if (!encoding)
  54                 encoding = "UTF-8";
  55         if (!git_commit_encoding)
  56                 git_commit_encoding = "UTF-8";
  57
  58         out->reencoded_message = NULL;
  59         out->message = commit->buffer;
  60         if (strcmp(encoding, git_commit_encoding))
  61                 out->reencoded_message = reencode_string(commit->buffer,
  62                                         git_commit_encoding, encoding);
  63         if (out->reencoded_message)
  64                 out->message = out->reencoded_message;
  65
  66         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
  67         abbrev_len = strlen(abbrev);
  68
  69         subject_len = find_commit_subject(out->message, &subject);
  70
  71         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
  72                               strlen("... ") + subject_len + 1);
  73         q = out->parent_label;
  74         q = mempcpy(q, "parent of ", strlen("parent of "));
  75         out->label = q;
  76         q = mempcpy(q, abbrev, abbrev_len);
  77         q = mempcpy(q, "... ", strlen("... "));
  78         out->subject = q;
  79         q = mempcpy(q, subject, subject_len);
  80         *q = '\0';
  81         return 0;
  82 }
  83
  84 static void free_message(struct commit_message *msg)
  85 {
  86         free(msg->parent_label);
  87         free(msg->reencoded_message);
  88 }
  89
  90 static char *get_encoding(const char *message)
  91 {
  92         const char *p = message, *eol;
  93
  94         while (*p && *p != '\n') {
  95                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
  96                         ; /* do nothing */
  97                 if (!prefixcmp(p, "encoding ")) {
  98                         char *result = xmalloc(eol - 8 - p);
  99                         strlcpy(result, p + 9, eol - 8 - p);
 100                         return result;
 101                 }
 102                 p = eol;
 103                 if (*p == '\n')
 104                         p++;
 105         }
 106         return NULL;
 107 }
 108
 109 static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
 110 {
 111         const char *filename;
 112         int fd;
 113         struct strbuf buf = STRBUF_INIT;
 114
 115         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 116
 117         filename = git_path("%s", pseudoref);
 118         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 119         if (fd < 0)
 120                 die_errno(_("Could not open '%s' for writing"), filename);
 121         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 122                 die_errno(_("Could not write to '%s'"), filename);
 123         strbuf_release(&buf);
 124 }
 125
 126 static void print_advice(int show_hint)
 127 {
 128         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 129
 130         if (msg) {
 131                 fprintf(stderr, "%s\n", msg);
 132                 /*
 133                  * A conflict has occured but the porcelain
 134                  * (typically rebase --interactive) wants to take care
 135                  * of the commit itself so remove CHERRY_PICK_HEAD
 136                  */
 137                 unlink(git_path("CHERRY_PICK_HEAD"));
 138                 return;
 139         }
 140
 141         if (show_hint) {
 142                 advise("after resolving the conflicts, mark the corrected paths");
 143                 advise("with 'git add <paths>' or 'git rm <paths>'");
 144                 advise("and commit the result with 'git commit'");
 145         }
 146 }
 147
 148 static void write_message(struct strbuf *msgbuf, const char *filename)
 149 {
 150         static struct lock_file msg_file;
 151
 152         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 153                                                LOCK_DIE_ON_ERROR);
 154         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 155                 die_errno(_("Could not write to %s"), filename);
 156         strbuf_release(msgbuf);
 157         if (commit_lock_file(&msg_file) < 0)
 158                 die(_("Error wrapping up %s"), filename);
 159 }
 160
 161 static struct tree *empty_tree(void)
 162 {
 163         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
 164 }
 165
 166 static int error_dirty_index(struct replay_opts *opts)
 167 {
 168         if (read_cache_unmerged())
 169                 return error_resolve_conflict(action_name(opts));
 170
 171         /* Different translation strings for cherry-pick and revert */
 172         if (opts->action == REPLAY_PICK)
 173                 error(_("Your local changes would be overwritten by cherry-pick."));
 174         else
 175                 error(_("Your local changes would be overwritten by revert."));
 176
 177         if (advice_commit_before_merge)
 178                 advise(_("Commit your changes or stash them to proceed."));
 179         return -1;
 180 }
 181
 182 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 183 {
 184         struct ref_lock *ref_lock;
 185
 186         read_cache();
 187         if (checkout_fast_forward(from, to))
 188                 exit(1); /* the callee should have complained already */
 189         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 190         return write_ref_sha1(ref_lock, to, "cherry-pick");
 191 }
 192
 193 static int do_recursive_merge(struct commit *base, struct commit *next,
 194                               const char *base_label, const char *next_label,
 195                               unsigned char *head, struct strbuf *msgbuf,
 196                               struct replay_opts *opts)
 197 {
 198         struct merge_options o;
 199         struct tree *result, *next_tree, *base_tree, *head_tree;
 200         int clean, index_fd;
 201         const char **xopt;
 202         static struct lock_file index_lock;
 203
 204         index_fd = hold_locked_index(&index_lock, 1);
 205
 206         read_cache();
 207
 208         init_merge_options(&o);
 209         o.ancestor = base ? base_label : "(empty tree)";
 210         o.branch1 = "HEAD";
 211         o.branch2 = next ? next_label : "(empty tree)";
 212
 213         head_tree = parse_tree_indirect(head);
 214         next_tree = next ? next->tree : empty_tree();
 215         base_tree = base ? base->tree : empty_tree();
 216
 217         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 218                 parse_merge_opt(&o, *xopt);
 219
 220         clean = merge_trees(&o,
 221                             head_tree,
 222                             next_tree, base_tree, &result);
 223
 224         if (active_cache_changed &&
 225             (write_cache(index_fd, active_cache, active_nr) ||
 226              commit_locked_index(&index_lock)))
 227                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 228                 die(_("%s: Unable to write new index file"), action_name(opts));
 229         rollback_lock_file(&index_lock);
 230
 231         if (!clean) {
 232                 int i;
 233                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 234                 for (i = 0; i < active_nr;) {
 235                         struct cache_entry *ce = active_cache[i++];
 236                         if (ce_stage(ce)) {
 237                                 strbuf_addch(msgbuf, '\t');
 238                                 strbuf_addstr(msgbuf, ce->name);
 239                                 strbuf_addch(msgbuf, '\n');
 240                                 while (i < active_nr && !strcmp(ce->name,
 241                                                 active_cache[i]->name))
 242                                         i++;
 243                         }
 244                 }
 245         }
 246
 247         return !clean;
 248 }
 249
 250 /*
 251  * If we are cherry-pick, and if the merge did not result in
 252  * hand-editing, we will hit this commit and inherit the original
 253  * author date and name.
 254  * If we are revert, or if our cherry-pick results in a hand merge,
 255  * we had better say that the current user is responsible for that.
 256  */
 257 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 258 {
 259         /* 6 is max possible length of our args array including NULL */
 260         const char *args[6];
 261         int i = 0;
 262
 263         args[i++] = "commit";
 264         args[i++] = "-n";
 265         if (opts->signoff)
 266                 args[i++] = "-s";
 267         if (!opts->edit) {
 268                 args[i++] = "-F";
 269                 args[i++] = defmsg;
 270         }
 271         args[i] = NULL;
 272
 273         return run_command_v_opt(args, RUN_GIT_CMD);
 274 }
 275
 276 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 277 {
 278         unsigned char head[20];
 279         struct commit *base, *next, *parent;
 280         const char *base_label, *next_label;
 281         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 282         char *defmsg = NULL;
 283         struct strbuf msgbuf = STRBUF_INIT;
 284         int res;
 285
 286         if (opts->no_commit) {
 287                 /*
 288                  * We do not intend to commit immediately.  We just want to
 289                  * merge the differences in, so let's compute the tree
 290                  * that represents the "current" state for merge-recursive
 291                  * to work on.
 292                  */
 293                 if (write_cache_as_tree(head, 0, NULL))
 294                         die (_("Your index file is unmerged."));
 295         } else {
 296                 if (get_sha1("HEAD", head))
 297                         return error(_("You do not have a valid HEAD"));
 298                 if (index_differs_from("HEAD", 0))
 299                         return error_dirty_index(opts);
 300         }
 301         discard_cache();
 302
 303         if (!commit->parents) {
 304                 parent = NULL;
 305         }
 306         else if (commit->parents->next) {
 307                 /* Reverting or cherry-picking a merge commit */
 308                 int cnt;
 309                 struct commit_list *p;
 310
 311                 if (!opts->mainline)
 312                         return error(_("Commit %s is a merge but no -m option was given."),
 313                                 sha1_to_hex(commit->object.sha1));
 314
 315                 for (cnt = 1, p = commit->parents;
 316                      cnt != opts->mainline && p;
 317                      cnt++)
 318                         p = p->next;
 319                 if (cnt != opts->mainline || !p)
 320                         return error(_("Commit %s does not have parent %d"),
 321                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 322                 parent = p->item;
 323         } else if (0 < opts->mainline)
 324                 return error(_("Mainline was specified but commit %s is not a merge."),
 325                         sha1_to_hex(commit->object.sha1));
 326         else
 327                 parent = commit->parents->item;
 328
 329         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 330                 return fast_forward_to(commit->object.sha1, head);
 331
 332         if (parent && parse_commit(parent) < 0)
 333                 /* TRANSLATORS: The first %s will be "revert" or
 334                    "cherry-pick", the second %s a SHA1 */
 335                 return error(_("%s: cannot parse parent commit %s"),
 336                         action_name(opts), sha1_to_hex(parent->object.sha1));
 337
 338         if (get_message(commit, &msg) != 0)
 339                 return error(_("Cannot get commit message for %s"),
 340                         sha1_to_hex(commit->object.sha1));
 341
 342         /*
 343          * "commit" is an existing commit.  We would want to apply
 344          * the difference it introduces since its first parent "prev"
 345          * on top of the current HEAD if we are cherry-pick.  Or the
 346          * reverse of it if we are revert.
 347          */
 348
 349         defmsg = git_pathdup("MERGE_MSG");
 350
 351         if (opts->action == REPLAY_REVERT) {
 352                 base = commit;
 353                 base_label = msg.label;
 354                 next = parent;
 355                 next_label = msg.parent_label;
 356                 strbuf_addstr(&msgbuf, "Revert \"");
 357                 strbuf_addstr(&msgbuf, msg.subject);
 358                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 359                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 360
 361                 if (commit->parents && commit->parents->next) {
 362                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 363                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 364                 }
 365                 strbuf_addstr(&msgbuf, ".\n");
 366         } else {
 367                 const char *p;
 368
 369                 base = parent;
 370                 base_label = msg.parent_label;
 371                 next = commit;
 372                 next_label = msg.label;
 373
 374                 /*
 375                  * Append the commit log message to msgbuf; it starts
 376                  * after the tree, parent, author, committer
 377                  * information followed by "\n\n".
 378                  */
 379                 p = strstr(msg.message, "\n\n");
 380                 if (p) {
 381                         p += 2;
 382                         strbuf_addstr(&msgbuf, p);
 383                 }
 384
 385                 if (opts->record_origin) {
 386                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 387                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 388                         strbuf_addstr(&msgbuf, ")\n");
 389                 }
 390         }
 391
 392         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REPLAY_REVERT) {
 393                 res = do_recursive_merge(base, next, base_label, next_label,
 394                                          head, &msgbuf, opts);
 395                 write_message(&msgbuf, defmsg);
 396         } else {
 397                 struct commit_list *common = NULL;
 398                 struct commit_list *remotes = NULL;
 399
 400                 write_message(&msgbuf, defmsg);
 401
 402                 commit_list_insert(base, &common);
 403                 commit_list_insert(next, &remotes);
 404                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 405                                         common, sha1_to_hex(head), remotes);
 406                 free_commit_list(common);
 407                 free_commit_list(remotes);
 408         }
 409
 410         /*
 411          * If the merge was clean or if it failed due to conflict, we write
 412          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 413          * However, if the merge did not even start, then we don't want to
 414          * write it at all.
 415          */
 416         if (opts->action == REPLAY_PICK && !opts->no_commit && (res == 0 || res == 1))
 417                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 418         if (opts->action == REPLAY_REVERT && ((opts->no_commit && res == 0) || res == 1))
 419                 write_cherry_pick_head(commit, "REVERT_HEAD");
 420
 421         if (res) {
 422                 error(opts->action == REPLAY_REVERT
 423                       ? _("could not revert %s... %s")
 424                       : _("could not apply %s... %s"),
 425                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 426                       msg.subject);
 427                 print_advice(res == 1);
 428                 rerere(opts->allow_rerere_auto);
 429         } else {
 430                 if (!opts->no_commit)
 431                         res = run_git_commit(defmsg, opts);
 432         }
 433
 434         free_message(&msg);
 435         free(defmsg);
 436
 437         return res;
 438 }
 439
 440 static void prepare_revs(struct replay_opts *opts)
 441 {
 442         if (opts->action != REPLAY_REVERT)
 443                 opts->revs->reverse ^= 1;
 444
 445         if (prepare_revision_walk(opts->revs))
 446                 die(_("revision walk setup failed"));
 447
 448         if (!opts->revs->commits)
 449                 die(_("empty commit set passed"));
 450 }
 451
 452 static void read_and_refresh_cache(struct replay_opts *opts)
 453 {
 454         static struct lock_file index_lock;
 455         int index_fd = hold_locked_index(&index_lock, 0);
 456         if (read_index_preload(&the_index, NULL) < 0)
 457                 die(_("git %s: failed to read the index"), action_name(opts));
 458         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 459         if (the_index.cache_changed) {
 460                 if (write_index(&the_index, index_fd) ||
 461                     commit_locked_index(&index_lock))
 462                         die(_("git %s: failed to refresh the index"), action_name(opts));
 463         }
 464         rollback_lock_file(&index_lock);
 465 }
 466
 467 /*
 468  * Append a commit to the end of the commit_list.
 469  *
 470  * next starts by pointing to the variable that holds the head of an
 471  * empty commit_list, and is updated to point to the "next" field of
 472  * the last item on the list as new commits are appended.
 473  *
 474  * Usage example:
 475  *
 476  *     struct commit_list *list;
 477  *     struct commit_list **next = &list;
 478  *
 479  *     next = commit_list_append(c1, next);
 480  *     next = commit_list_append(c2, next);
 481  *     assert(commit_list_count(list) == 2);
 482  *     return list;
 483  */
 484 static struct commit_list **commit_list_append(struct commit *commit,
 485                                                struct commit_list **next)
 486 {
 487         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 488         new->item = commit;
 489         *next = new;
 490         new->next = NULL;
 491         return &new->next;
 492 }
 493
 494 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 495                 struct replay_opts *opts)
 496 {
 497         struct commit_list *cur = NULL;
 498         const char *sha1_abbrev = NULL;
 499         const char *action_str = opts->action == REPLAY_REVERT ? "revert" : "pick";
 500         const char *subject;
 501         int subject_len;
 502
 503         for (cur = todo_list; cur; cur = cur->next) {
 504                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 505                 subject_len = find_commit_subject(cur->item->buffer, &subject);
 506                 strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
 507                         subject_len, subject);
 508         }
 509         return 0;
 510 }
 511
 512 static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
 513 {
 514         unsigned char commit_sha1[20];
 515         enum replay_action action;
 516         char *end_of_object_name;
 517         int saved, status, padding;
 518
 519         if (!prefixcmp(bol, "pick")) {
 520                 action = REPLAY_PICK;
 521                 bol += strlen("pick");
 522         } else if (!prefixcmp(bol, "revert")) {
 523                 action = REPLAY_REVERT;
 524                 bol += strlen("revert");
 525         } else
 526                 return NULL;
 527
 528         /* Eat up extra spaces/ tabs before object name */
 529         padding = strspn(bol, " \t");
 530         if (!padding)
 531                 return NULL;
 532         bol += padding;
 533
 534         end_of_object_name = bol + strcspn(bol, " \t\n");
 535         saved = *end_of_object_name;
 536         *end_of_object_name = '\0';
 537         status = get_sha1(bol, commit_sha1);
 538         *end_of_object_name = saved;
 539
 540         /*
 541          * Verify that the action matches up with the one in
 542          * opts; we don't support arbitrary instructions
 543          */
 544         if (action != opts->action) {
 545                 const char *action_str;
 546                 action_str = action == REPLAY_REVERT ? "revert" : "cherry-pick";
 547                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 548                 return NULL;
 549         }
 550
 551         if (status < 0)
 552                 return NULL;
 553
 554         return lookup_commit_reference(commit_sha1);
 555 }
 556
 557 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 558                         struct replay_opts *opts)
 559 {
 560         struct commit_list **next = todo_list;
 561         struct commit *commit;
 562         char *p = buf;
 563         int i;
 564
 565         for (i = 1; *p; i++) {
 566                 char *eol = strchrnul(p, '\n');
 567                 commit = parse_insn_line(p, eol, opts);
 568                 if (!commit)
 569                         return error(_("Could not parse line %d."), i);
 570                 next = commit_list_append(commit, next);
 571                 p = *eol ? eol + 1 : eol;
 572         }
 573         if (!*todo_list)
 574                 return error(_("No commits parsed."));
 575         return 0;
 576 }
 577
 578 static void read_populate_todo(struct commit_list **todo_list,
 579                         struct replay_opts *opts)
 580 {
 581         const char *todo_file = git_path(SEQ_TODO_FILE);
 582         struct strbuf buf = STRBUF_INIT;
 583         int fd, res;
 584
 585         fd = open(todo_file, O_RDONLY);
 586         if (fd < 0)
 587                 die_errno(_("Could not open %s"), todo_file);
 588         if (strbuf_read(&buf, fd, 0) < 0) {
 589                 close(fd);
 590                 strbuf_release(&buf);
 591                 die(_("Could not read %s."), todo_file);
 592         }
 593         close(fd);
 594
 595         res = parse_insn_buffer(buf.buf, todo_list, opts);
 596         strbuf_release(&buf);
 597         if (res)
 598                 die(_("Unusable instruction sheet: %s"), todo_file);
 599 }
 600
 601 static int populate_opts_cb(const char *key, const char *value, void *data)
 602 {
 603         struct replay_opts *opts = data;
 604         int error_flag = 1;
 605
 606         if (!value)
 607                 error_flag = 0;
 608         else if (!strcmp(key, "options.no-commit"))
 609                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 610         else if (!strcmp(key, "options.edit"))
 611                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 612         else if (!strcmp(key, "options.signoff"))
 613                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 614         else if (!strcmp(key, "options.record-origin"))
 615                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 616         else if (!strcmp(key, "options.allow-ff"))
 617                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 618         else if (!strcmp(key, "options.mainline"))
 619                 opts->mainline = git_config_int(key, value);
 620         else if (!strcmp(key, "options.strategy"))
 621                 git_config_string(&opts->strategy, key, value);
 622         else if (!strcmp(key, "options.strategy-option")) {
 623                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 624                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 625         } else
 626                 return error(_("Invalid key: %s"), key);
 627
 628         if (!error_flag)
 629                 return error(_("Invalid value for %s: %s"), key, value);
 630
 631         return 0;
 632 }
 633
 634 static void read_populate_opts(struct replay_opts **opts_ptr)
 635 {
 636         const char *opts_file = git_path(SEQ_OPTS_FILE);
 637
 638         if (!file_exists(opts_file))
 639                 return;
 640         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 641                 die(_("Malformed options sheet: %s"), opts_file);
 642 }
 643
 644 static void walk_revs_populate_todo(struct commit_list **todo_list,
 645                                 struct replay_opts *opts)
 646 {
 647         struct commit *commit;
 648         struct commit_list **next;
 649
 650         prepare_revs(opts);
 651
 652         next = todo_list;
 653         while ((commit = get_revision(opts->revs)))
 654                 next = commit_list_append(commit, next);
 655 }
 656
 657 static int create_seq_dir(void)
 658 {
 659         const char *seq_dir = git_path(SEQ_DIR);
 660
 661         if (file_exists(seq_dir)) {
 662                 error(_("a cherry-pick or revert is already in progress"));
 663                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 664                 return -1;
 665         }
 666         else if (mkdir(seq_dir, 0777) < 0)
 667                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 668         return 0;
 669 }
 670
 671 static void save_head(const char *head)
 672 {
 673         const char *head_file = git_path(SEQ_HEAD_FILE);
 674         static struct lock_file head_lock;
 675         struct strbuf buf = STRBUF_INIT;
 676         int fd;
 677
 678         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 679         strbuf_addf(&buf, "%s\n", head);
 680         if (write_in_full(fd, buf.buf, buf.len) < 0)
 681                 die_errno(_("Could not write to %s"), head_file);
 682         if (commit_lock_file(&head_lock) < 0)
 683                 die(_("Error wrapping up %s."), head_file);
 684 }
 685
 686 static int reset_for_rollback(const unsigned char *sha1)
 687 {
 688         const char *argv[4];    /* reset --merge <arg> + NULL */
 689         argv[0] = "reset";
 690         argv[1] = "--merge";
 691         argv[2] = sha1_to_hex(sha1);
 692         argv[3] = NULL;
 693         return run_command_v_opt(argv, RUN_GIT_CMD);
 694 }
 695
 696 static int rollback_single_pick(void)
 697 {
 698         unsigned char head_sha1[20];
 699
 700         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 701             !file_exists(git_path("REVERT_HEAD")))
 702                 return error(_("no cherry-pick or revert in progress"));
 703         if (read_ref_full("HEAD", head_sha1, 0, NULL))
 704                 return error(_("cannot resolve HEAD"));
 705         if (is_null_sha1(head_sha1))
 706                 return error(_("cannot abort from a branch yet to be born"));
 707         return reset_for_rollback(head_sha1);
 708 }
 709
 710 static int sequencer_rollback(struct replay_opts *opts)
 711 {
 712         const char *filename;
 713         FILE *f;
 714         unsigned char sha1[20];
 715         struct strbuf buf = STRBUF_INIT;
 716
 717         filename = git_path(SEQ_HEAD_FILE);
 718         f = fopen(filename, "r");
 719         if (!f && errno == ENOENT) {
 720                 /*
 721                  * There is no multiple-cherry-pick in progress.
 722                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 723                  * a single-cherry-pick in progress, abort that.
 724                  */
 725                 return rollback_single_pick();
 726         }
 727         if (!f)
 728                 return error(_("cannot open %s: %s"), filename,
 729                                                 strerror(errno));
 730         if (strbuf_getline(&buf, f, '\n')) {
 731                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 732                         strerror(errno) : _("unexpected end of file"));
 733                 fclose(f);
 734                 goto fail;
 735         }
 736         fclose(f);
 737         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 738                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 739                         filename);
 740                 goto fail;
 741         }
 742         if (reset_for_rollback(sha1))
 743                 goto fail;
 744         remove_sequencer_state();
 745         strbuf_release(&buf);
 746         return 0;
 747 fail:
 748         strbuf_release(&buf);
 749         return -1;
 750 }
 751
 752 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 753 {
 754         const char *todo_file = git_path(SEQ_TODO_FILE);
 755         static struct lock_file todo_lock;
 756         struct strbuf buf = STRBUF_INIT;
 757         int fd;
 758
 759         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 760         if (format_todo(&buf, todo_list, opts) < 0)
 761                 die(_("Could not format %s."), todo_file);
 762         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 763                 strbuf_release(&buf);
 764                 die_errno(_("Could not write to %s"), todo_file);
 765         }
 766         if (commit_lock_file(&todo_lock) < 0) {
 767                 strbuf_release(&buf);
 768                 die(_("Error wrapping up %s."), todo_file);
 769         }
 770         strbuf_release(&buf);
 771 }
 772
 773 static void save_opts(struct replay_opts *opts)
 774 {
 775         const char *opts_file = git_path(SEQ_OPTS_FILE);
 776
 777         if (opts->no_commit)
 778                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 779         if (opts->edit)
 780                 git_config_set_in_file(opts_file, "options.edit", "true");
 781         if (opts->signoff)
 782                 git_config_set_in_file(opts_file, "options.signoff", "true");
 783         if (opts->record_origin)
 784                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 785         if (opts->allow_ff)
 786                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 787         if (opts->mainline) {
 788                 struct strbuf buf = STRBUF_INIT;
 789                 strbuf_addf(&buf, "%d", opts->mainline);
 790                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 791                 strbuf_release(&buf);
 792         }
 793         if (opts->strategy)
 794                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 795         if (opts->xopts) {
 796                 int i;
 797                 for (i = 0; i < opts->xopts_nr; i++)
 798                         git_config_set_multivar_in_file(opts_file,
 799                                                         "options.strategy-option",
 800                                                         opts->xopts[i], "^$", 0);
 801         }
 802 }
 803
 804 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
 805 {
 806         struct commit_list *cur;
 807         int res;
 808
 809         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 810         if (opts->allow_ff)
 811                 assert(!(opts->signoff || opts->no_commit ||
 812                                 opts->record_origin || opts->edit));
 813         read_and_refresh_cache(opts);
 814
 815         for (cur = todo_list; cur; cur = cur->next) {
 816                 save_todo(cur, opts);
 817                 res = do_pick_commit(cur->item, opts);
 818                 if (res)
 819                         return res;
 820         }
 821
 822         /*
 823          * Sequence of picks finished successfully; cleanup by
 824          * removing the .git/sequencer directory
 825          */
 826         remove_sequencer_state();
 827         return 0;
 828 }
 829
 830 static int continue_single_pick(void)
 831 {
 832         const char *argv[] = { "commit", NULL };
 833
 834         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 835             !file_exists(git_path("REVERT_HEAD")))
 836                 return error(_("no cherry-pick or revert in progress"));
 837         return run_command_v_opt(argv, RUN_GIT_CMD);
 838 }
 839
 840 static int sequencer_continue(struct replay_opts *opts)
 841 {
 842         struct commit_list *todo_list = NULL;
 843
 844         if (!file_exists(git_path(SEQ_TODO_FILE)))
 845                 return continue_single_pick();
 846         read_populate_opts(&opts);
 847         read_populate_todo(&todo_list, opts);
 848
 849         /* Verify that the conflict has been resolved */
 850         if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
 851             file_exists(git_path("REVERT_HEAD"))) {
 852                 int ret = continue_single_pick();
 853                 if (ret)
 854                         return ret;
 855         }
 856         if (index_differs_from("HEAD", 0))
 857                 return error_dirty_index(opts);
 858         todo_list = todo_list->next;
 859         return pick_commits(todo_list, opts);
 860 }
 861
 862 static int single_pick(struct commit *cmit, struct replay_opts *opts)
 863 {
 864         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 865         return do_pick_commit(cmit, opts);
 866 }
 867
 868 int sequencer_pick_revisions(struct replay_opts *opts)
 869 {
 870         struct commit_list *todo_list = NULL;
 871         unsigned char sha1[20];
 872
 873         if (opts->subcommand == REPLAY_NONE)
 874                 assert(opts->revs);
 875
 876         read_and_refresh_cache(opts);
 877
 878         /*
 879          * Decide what to do depending on the arguments; a fresh
 880          * cherry-pick should be handled differently from an existing
 881          * one that is being continued
 882          */
 883         if (opts->subcommand == REPLAY_REMOVE_STATE) {
 884                 remove_sequencer_state();
 885                 return 0;
 886         }
 887         if (opts->subcommand == REPLAY_ROLLBACK)
 888                 return sequencer_rollback(opts);
 889         if (opts->subcommand == REPLAY_CONTINUE)
 890                 return sequencer_continue(opts);
 891
 892         /*
 893          * If we were called as "git cherry-pick <commit>", just
 894          * cherry-pick/revert it, set CHERRY_PICK_HEAD /
 895          * REVERT_HEAD, and don't touch the sequencer state.
 896          * This means it is possible to cherry-pick in the middle
 897          * of a cherry-pick sequence.
 898          */
 899         if (opts->revs->cmdline.nr == 1 &&
 900             opts->revs->cmdline.rev->whence == REV_CMD_REV &&
 901             opts->revs->no_walk &&
 902             !opts->revs->cmdline.rev->flags) {
 903                 struct commit *cmit;
 904                 if (prepare_revision_walk(opts->revs))
 905                         die(_("revision walk setup failed"));
 906                 cmit = get_revision(opts->revs);
 907                 if (!cmit || get_revision(opts->revs))
 908                         die("BUG: expected exactly one commit from walk");
 909                 return single_pick(cmit, opts);
 910         }
 911
 912         /*
 913          * Start a new cherry-pick/ revert sequence; but
 914          * first, make sure that an existing one isn't in
 915          * progress
 916          */
 917
 918         walk_revs_populate_todo(&todo_list, opts);
 919         if (create_seq_dir() < 0)
 920                 return -1;
 921         if (get_sha1("HEAD", sha1)) {
 922                 if (opts->action == REPLAY_REVERT)
 923                         return error(_("Can't revert as initial commit"));
 924                 return error(_("Can't cherry-pick into empty head"));
 925         }
 926         save_head(sha1_to_hex(sha1));
 927         save_opts(opts);
 928         return pick_commits(todo_list, opts);
 929 }