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