git.oblomov.eu Git - git/blob - 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, struct replay_opts *opts)
 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                 if (opts->no_commit)
 143                         advise(_("after resolving the conflicts, mark the corrected paths\n"
 144                                  "with 'git add <paths>' or 'git rm <paths>'"));
 145                 else
 146                         advise(_("after resolving the conflicts, mark the corrected paths\n"
 147                                  "with 'git add <paths>' or 'git rm <paths>'\n"
 148                                  "and commit the result with 'git commit'"));
 149         }
 150 }
 151
 152 static void write_message(struct strbuf *msgbuf, const char *filename)
 153 {
 154         static struct lock_file msg_file;
 155
 156         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 157                                                LOCK_DIE_ON_ERROR);
 158         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 159                 die_errno(_("Could not write to %s"), filename);
 160         strbuf_release(msgbuf);
 161         if (commit_lock_file(&msg_file) < 0)
 162                 die(_("Error wrapping up %s"), filename);
 163 }
 164
 165 static struct tree *empty_tree(void)
 166 {
 167         return lookup_tree(EMPTY_TREE_SHA1_BIN);
 168 }
 169
 170 static int error_dirty_index(struct replay_opts *opts)
 171 {
 172         if (read_cache_unmerged())
 173                 return error_resolve_conflict(action_name(opts));
 174
 175         /* Different translation strings for cherry-pick and revert */
 176         if (opts->action == REPLAY_PICK)
 177                 error(_("Your local changes would be overwritten by cherry-pick."));
 178         else
 179                 error(_("Your local changes would be overwritten by revert."));
 180
 181         if (advice_commit_before_merge)
 182                 advise(_("Commit your changes or stash them to proceed."));
 183         return -1;
 184 }
 185
 186 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 187 {
 188         struct ref_lock *ref_lock;
 189
 190         read_cache();
 191         if (checkout_fast_forward(from, to))
 192                 exit(1); /* the callee should have complained already */
 193         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 194         return write_ref_sha1(ref_lock, to, "cherry-pick");
 195 }
 196
 197 static int do_recursive_merge(struct commit *base, struct commit *next,
 198                               const char *base_label, const char *next_label,
 199                               unsigned char *head, struct strbuf *msgbuf,
 200                               struct replay_opts *opts)
 201 {
 202         struct merge_options o;
 203         struct tree *result, *next_tree, *base_tree, *head_tree;
 204         int clean, index_fd;
 205         const char **xopt;
 206         static struct lock_file index_lock;
 207
 208         index_fd = hold_locked_index(&index_lock, 1);
 209
 210         read_cache();
 211
 212         init_merge_options(&o);
 213         o.ancestor = base ? base_label : "(empty tree)";
 214         o.branch1 = "HEAD";
 215         o.branch2 = next ? next_label : "(empty tree)";
 216
 217         head_tree = parse_tree_indirect(head);
 218         next_tree = next ? next->tree : empty_tree();
 219         base_tree = base ? base->tree : empty_tree();
 220
 221         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 222                 parse_merge_opt(&o, *xopt);
 223
 224         clean = merge_trees(&o,
 225                             head_tree,
 226                             next_tree, base_tree, &result);
 227
 228         if (active_cache_changed &&
 229             (write_cache(index_fd, active_cache, active_nr) ||
 230              commit_locked_index(&index_lock)))
 231                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 232                 die(_("%s: Unable to write new index file"), action_name(opts));
 233         rollback_lock_file(&index_lock);
 234
 235         if (!clean) {
 236                 int i;
 237                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 238                 for (i = 0; i < active_nr;) {
 239                         struct cache_entry *ce = active_cache[i++];
 240                         if (ce_stage(ce)) {
 241                                 strbuf_addch(msgbuf, '\t');
 242                                 strbuf_addstr(msgbuf, ce->name);
 243                                 strbuf_addch(msgbuf, '\n');
 244                                 while (i < active_nr && !strcmp(ce->name,
 245                                                 active_cache[i]->name))
 246                                         i++;
 247                         }
 248                 }
 249         }
 250
 251         return !clean;
 252 }
 253
 254 /*
 255  * If we are cherry-pick, and if the merge did not result in
 256  * hand-editing, we will hit this commit and inherit the original
 257  * author date and name.
 258  * If we are revert, or if our cherry-pick results in a hand merge,
 259  * we had better say that the current user is responsible for that.
 260  */
 261 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 262 {
 263         /* 6 is max possible length of our args array including NULL */
 264         const char *args[6];
 265         int i = 0;
 266
 267         args[i++] = "commit";
 268         args[i++] = "-n";
 269         if (opts->signoff)
 270                 args[i++] = "-s";
 271         if (!opts->edit) {
 272                 args[i++] = "-F";
 273                 args[i++] = defmsg;
 274         }
 275         args[i] = NULL;
 276
 277         return run_command_v_opt(args, RUN_GIT_CMD);
 278 }
 279
 280 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 281 {
 282         unsigned char head[20];
 283         struct commit *base, *next, *parent;
 284         const char *base_label, *next_label;
 285         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 286         char *defmsg = NULL;
 287         struct strbuf msgbuf = STRBUF_INIT;
 288         int res;
 289
 290         if (opts->no_commit) {
 291                 /*
 292                  * We do not intend to commit immediately.  We just want to
 293                  * merge the differences in, so let's compute the tree
 294                  * that represents the "current" state for merge-recursive
 295                  * to work on.
 296                  */
 297                 if (write_cache_as_tree(head, 0, NULL))
 298                         die (_("Your index file is unmerged."));
 299         } else {
 300                 if (get_sha1("HEAD", head))
 301                         return error(_("You do not have a valid HEAD"));
 302                 if (index_differs_from("HEAD", 0))
 303                         return error_dirty_index(opts);
 304         }
 305         discard_cache();
 306
 307         if (!commit->parents) {
 308                 parent = NULL;
 309         }
 310         else if (commit->parents->next) {
 311                 /* Reverting or cherry-picking a merge commit */
 312                 int cnt;
 313                 struct commit_list *p;
 314
 315                 if (!opts->mainline)
 316                         return error(_("Commit %s is a merge but no -m option was given."),
 317                                 sha1_to_hex(commit->object.sha1));
 318
 319                 for (cnt = 1, p = commit->parents;
 320                      cnt != opts->mainline && p;
 321                      cnt++)
 322                         p = p->next;
 323                 if (cnt != opts->mainline || !p)
 324                         return error(_("Commit %s does not have parent %d"),
 325                                 sha1_to_hex(commit->object.sha1), opts->mainline);
 326                 parent = p->item;
 327         } else if (0 < opts->mainline)
 328                 return error(_("Mainline was specified but commit %s is not a merge."),
 329                         sha1_to_hex(commit->object.sha1));
 330         else
 331                 parent = commit->parents->item;
 332
 333         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 334                 return fast_forward_to(commit->object.sha1, head);
 335
 336         if (parent && parse_commit(parent) < 0)
 337                 /* TRANSLATORS: The first %s will be "revert" or
 338                    "cherry-pick", the second %s a SHA1 */
 339                 return error(_("%s: cannot parse parent commit %s"),
 340                         action_name(opts), sha1_to_hex(parent->object.sha1));
 341
 342         if (get_message(commit, &msg) != 0)
 343                 return error(_("Cannot get commit message for %s"),
 344                         sha1_to_hex(commit->object.sha1));
 345
 346         /*
 347          * "commit" is an existing commit.  We would want to apply
 348          * the difference it introduces since its first parent "prev"
 349          * on top of the current HEAD if we are cherry-pick.  Or the
 350          * reverse of it if we are revert.
 351          */
 352
 353         defmsg = git_pathdup("MERGE_MSG");
 354
 355         if (opts->action == REPLAY_REVERT) {
 356                 base = commit;
 357                 base_label = msg.label;
 358                 next = parent;
 359                 next_label = msg.parent_label;
 360                 strbuf_addstr(&msgbuf, "Revert \"");
 361                 strbuf_addstr(&msgbuf, msg.subject);
 362                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 363                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 364
 365                 if (commit->parents && commit->parents->next) {
 366                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 367                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 368                 }
 369                 strbuf_addstr(&msgbuf, ".\n");
 370         } else {
 371                 const char *p;
 372
 373                 base = parent;
 374                 base_label = msg.parent_label;
 375                 next = commit;
 376                 next_label = msg.label;
 377
 378                 /*
 379                  * Append the commit log message to msgbuf; it starts
 380                  * after the tree, parent, author, committer
 381                  * information followed by "\n\n".
 382                  */
 383                 p = strstr(msg.message, "\n\n");
 384                 if (p) {
 385                         p += 2;
 386                         strbuf_addstr(&msgbuf, p);
 387                 }
 388
 389                 if (opts->record_origin) {
 390                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 391                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 392                         strbuf_addstr(&msgbuf, ")\n");
 393                 }
 394         }
 395
 396         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REPLAY_REVERT) {
 397                 res = do_recursive_merge(base, next, base_label, next_label,
 398                                          head, &msgbuf, opts);
 399                 write_message(&msgbuf, defmsg);
 400         } else {
 401                 struct commit_list *common = NULL;
 402                 struct commit_list *remotes = NULL;
 403
 404                 write_message(&msgbuf, defmsg);
 405
 406                 commit_list_insert(base, &common);
 407                 commit_list_insert(next, &remotes);
 408                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 409                                         common, sha1_to_hex(head), remotes);
 410                 free_commit_list(common);
 411                 free_commit_list(remotes);
 412         }
 413
 414         /*
 415          * If the merge was clean or if it failed due to conflict, we write
 416          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
 417          * However, if the merge did not even start, then we don't want to
 418          * write it at all.
 419          */
 420         if (opts->action == REPLAY_PICK && !opts->no_commit && (res == 0 || res == 1))
 421                 write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
 422         if (opts->action == REPLAY_REVERT && ((opts->no_commit && res == 0) || res == 1))
 423                 write_cherry_pick_head(commit, "REVERT_HEAD");
 424
 425         if (res) {
 426                 error(opts->action == REPLAY_REVERT
 427                       ? _("could not revert %s... %s")
 428                       : _("could not apply %s... %s"),
 429                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 430                       msg.subject);
 431                 print_advice(res == 1, opts);
 432                 rerere(opts->allow_rerere_auto);
 433         } else {
 434                 if (!opts->no_commit)
 435                         res = run_git_commit(defmsg, opts);
 436         }
 437
 438         free_message(&msg);
 439         free(defmsg);
 440
 441         return res;
 442 }
 443
 444 static void prepare_revs(struct replay_opts *opts)
 445 {
 446         if (opts->action != REPLAY_REVERT)
 447                 opts->revs->reverse ^= 1;
 448
 449         if (prepare_revision_walk(opts->revs))
 450                 die(_("revision walk setup failed"));
 451
 452         if (!opts->revs->commits)
 453                 die(_("empty commit set passed"));
 454 }
 455
 456 static void read_and_refresh_cache(struct replay_opts *opts)
 457 {
 458         static struct lock_file index_lock;
 459         int index_fd = hold_locked_index(&index_lock, 0);
 460         if (read_index_preload(&the_index, NULL) < 0)
 461                 die(_("git %s: failed to read the index"), action_name(opts));
 462         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 463         if (the_index.cache_changed) {
 464                 if (write_index(&the_index, index_fd) ||
 465                     commit_locked_index(&index_lock))
 466                         die(_("git %s: failed to refresh the index"), action_name(opts));
 467         }
 468         rollback_lock_file(&index_lock);
 469 }
 470
 471 /*
 472  * Append a commit to the end of the commit_list.
 473  *
 474  * next starts by pointing to the variable that holds the head of an
 475  * empty commit_list, and is updated to point to the "next" field of
 476  * the last item on the list as new commits are appended.
 477  *
 478  * Usage example:
 479  *
 480  *     struct commit_list *list;
 481  *     struct commit_list **next = &list;
 482  *
 483  *     next = commit_list_append(c1, next);
 484  *     next = commit_list_append(c2, next);
 485  *     assert(commit_list_count(list) == 2);
 486  *     return list;
 487  */
 488 static struct commit_list **commit_list_append(struct commit *commit,
 489                                                struct commit_list **next)
 490 {
 491         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 492         new->item = commit;
 493         *next = new;
 494         new->next = NULL;
 495         return &new->next;
 496 }
 497
 498 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 499                 struct replay_opts *opts)
 500 {
 501         struct commit_list *cur = NULL;
 502         const char *sha1_abbrev = NULL;
 503         const char *action_str = opts->action == REPLAY_REVERT ? "revert" : "pick";
 504         const char *subject;
 505         int subject_len;
 506
 507         for (cur = todo_list; cur; cur = cur->next) {
 508                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 509                 subject_len = find_commit_subject(cur->item->buffer, &subject);
 510                 strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
 511                         subject_len, subject);
 512         }
 513         return 0;
 514 }
 515
 516 static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
 517 {
 518         unsigned char commit_sha1[20];
 519         enum replay_action action;
 520         char *end_of_object_name;
 521         int saved, status, padding;
 522
 523         if (!prefixcmp(bol, "pick")) {
 524                 action = REPLAY_PICK;
 525                 bol += strlen("pick");
 526         } else if (!prefixcmp(bol, "revert")) {
 527                 action = REPLAY_REVERT;
 528                 bol += strlen("revert");
 529         } else
 530                 return NULL;
 531
 532         /* Eat up extra spaces/ tabs before object name */
 533         padding = strspn(bol, " \t");
 534         if (!padding)
 535                 return NULL;
 536         bol += padding;
 537
 538         end_of_object_name = bol + strcspn(bol, " \t\n");
 539         saved = *end_of_object_name;
 540         *end_of_object_name = '\0';
 541         status = get_sha1(bol, commit_sha1);
 542         *end_of_object_name = saved;
 543
 544         /*
 545          * Verify that the action matches up with the one in
 546          * opts; we don't support arbitrary instructions
 547          */
 548         if (action != opts->action) {
 549                 const char *action_str;
 550                 action_str = action == REPLAY_REVERT ? "revert" : "cherry-pick";
 551                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
 552                 return NULL;
 553         }
 554
 555         if (status < 0)
 556                 return NULL;
 557
 558         return lookup_commit_reference(commit_sha1);
 559 }
 560
 561 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 562                         struct replay_opts *opts)
 563 {
 564         struct commit_list **next = todo_list;
 565         struct commit *commit;
 566         char *p = buf;
 567         int i;
 568
 569         for (i = 1; *p; i++) {
 570                 char *eol = strchrnul(p, '\n');
 571                 commit = parse_insn_line(p, eol, opts);
 572                 if (!commit)
 573                         return error(_("Could not parse line %d."), i);
 574                 next = commit_list_append(commit, next);
 575                 p = *eol ? eol + 1 : eol;
 576         }
 577         if (!*todo_list)
 578                 return error(_("No commits parsed."));
 579         return 0;
 580 }
 581
 582 static void read_populate_todo(struct commit_list **todo_list,
 583                         struct replay_opts *opts)
 584 {
 585         const char *todo_file = git_path(SEQ_TODO_FILE);
 586         struct strbuf buf = STRBUF_INIT;
 587         int fd, res;
 588
 589         fd = open(todo_file, O_RDONLY);
 590         if (fd < 0)
 591                 die_errno(_("Could not open %s"), todo_file);
 592         if (strbuf_read(&buf, fd, 0) < 0) {
 593                 close(fd);
 594                 strbuf_release(&buf);
 595                 die(_("Could not read %s."), todo_file);
 596         }
 597         close(fd);
 598
 599         res = parse_insn_buffer(buf.buf, todo_list, opts);
 600         strbuf_release(&buf);
 601         if (res)
 602                 die(_("Unusable instruction sheet: %s"), todo_file);
 603 }
 604
 605 static int populate_opts_cb(const char *key, const char *value, void *data)
 606 {
 607         struct replay_opts *opts = data;
 608         int error_flag = 1;
 609
 610         if (!value)
 611                 error_flag = 0;
 612         else if (!strcmp(key, "options.no-commit"))
 613                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
 614         else if (!strcmp(key, "options.edit"))
 615                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
 616         else if (!strcmp(key, "options.signoff"))
 617                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
 618         else if (!strcmp(key, "options.record-origin"))
 619                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
 620         else if (!strcmp(key, "options.allow-ff"))
 621                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
 622         else if (!strcmp(key, "options.mainline"))
 623                 opts->mainline = git_config_int(key, value);
 624         else if (!strcmp(key, "options.strategy"))
 625                 git_config_string(&opts->strategy, key, value);
 626         else if (!strcmp(key, "options.strategy-option")) {
 627                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 628                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
 629         } else
 630                 return error(_("Invalid key: %s"), key);
 631
 632         if (!error_flag)
 633                 return error(_("Invalid value for %s: %s"), key, value);
 634
 635         return 0;
 636 }
 637
 638 static void read_populate_opts(struct replay_opts **opts_ptr)
 639 {
 640         const char *opts_file = git_path(SEQ_OPTS_FILE);
 641
 642         if (!file_exists(opts_file))
 643                 return;
 644         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
 645                 die(_("Malformed options sheet: %s"), opts_file);
 646 }
 647
 648 static void walk_revs_populate_todo(struct commit_list **todo_list,
 649                                 struct replay_opts *opts)
 650 {
 651         struct commit *commit;
 652         struct commit_list **next;
 653
 654         prepare_revs(opts);
 655
 656         next = todo_list;
 657         while ((commit = get_revision(opts->revs)))
 658                 next = commit_list_append(commit, next);
 659 }
 660
 661 static int create_seq_dir(void)
 662 {
 663         const char *seq_dir = git_path(SEQ_DIR);
 664
 665         if (file_exists(seq_dir)) {
 666                 error(_("a cherry-pick or revert is already in progress"));
 667                 advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
 668                 return -1;
 669         }
 670         else if (mkdir(seq_dir, 0777) < 0)
 671                 die_errno(_("Could not create sequencer directory %s"), seq_dir);
 672         return 0;
 673 }
 674
 675 static void save_head(const char *head)
 676 {
 677         const char *head_file = git_path(SEQ_HEAD_FILE);
 678         static struct lock_file head_lock;
 679         struct strbuf buf = STRBUF_INIT;
 680         int fd;
 681
 682         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 683         strbuf_addf(&buf, "%s\n", head);
 684         if (write_in_full(fd, buf.buf, buf.len) < 0)
 685                 die_errno(_("Could not write to %s"), head_file);
 686         if (commit_lock_file(&head_lock) < 0)
 687                 die(_("Error wrapping up %s."), head_file);
 688 }
 689
 690 static int reset_for_rollback(const unsigned char *sha1)
 691 {
 692         const char *argv[4];    /* reset --merge <arg> + NULL */
 693         argv[0] = "reset";
 694         argv[1] = "--merge";
 695         argv[2] = sha1_to_hex(sha1);
 696         argv[3] = NULL;
 697         return run_command_v_opt(argv, RUN_GIT_CMD);
 698 }
 699
 700 static int rollback_single_pick(void)
 701 {
 702         unsigned char head_sha1[20];
 703
 704         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 705             !file_exists(git_path("REVERT_HEAD")))
 706                 return error(_("no cherry-pick or revert in progress"));
 707         if (read_ref_full("HEAD", head_sha1, 0, NULL))
 708                 return error(_("cannot resolve HEAD"));
 709         if (is_null_sha1(head_sha1))
 710                 return error(_("cannot abort from a branch yet to be born"));
 711         return reset_for_rollback(head_sha1);
 712 }
 713
 714 static int sequencer_rollback(struct replay_opts *opts)
 715 {
 716         const char *filename;
 717         FILE *f;
 718         unsigned char sha1[20];
 719         struct strbuf buf = STRBUF_INIT;
 720
 721         filename = git_path(SEQ_HEAD_FILE);
 722         f = fopen(filename, "r");
 723         if (!f && errno == ENOENT) {
 724                 /*
 725                  * There is no multiple-cherry-pick in progress.
 726                  * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
 727                  * a single-cherry-pick in progress, abort that.
 728                  */
 729                 return rollback_single_pick();
 730         }
 731         if (!f)
 732                 return error(_("cannot open %s: %s"), filename,
 733                                                 strerror(errno));
 734         if (strbuf_getline(&buf, f, '\n')) {
 735                 error(_("cannot read %s: %s"), filename, ferror(f) ?
 736                         strerror(errno) : _("unexpected end of file"));
 737                 fclose(f);
 738                 goto fail;
 739         }
 740         fclose(f);
 741         if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
 742                 error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
 743                         filename);
 744                 goto fail;
 745         }
 746         if (reset_for_rollback(sha1))
 747                 goto fail;
 748         remove_sequencer_state();
 749         strbuf_release(&buf);
 750         return 0;
 751 fail:
 752         strbuf_release(&buf);
 753         return -1;
 754 }
 755
 756 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 757 {
 758         const char *todo_file = git_path(SEQ_TODO_FILE);
 759         static struct lock_file todo_lock;
 760         struct strbuf buf = STRBUF_INIT;
 761         int fd;
 762
 763         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 764         if (format_todo(&buf, todo_list, opts) < 0)
 765                 die(_("Could not format %s."), todo_file);
 766         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 767                 strbuf_release(&buf);
 768                 die_errno(_("Could not write to %s"), todo_file);
 769         }
 770         if (commit_lock_file(&todo_lock) < 0) {
 771                 strbuf_release(&buf);
 772                 die(_("Error wrapping up %s."), todo_file);
 773         }
 774         strbuf_release(&buf);
 775 }
 776
 777 static void save_opts(struct replay_opts *opts)
 778 {
 779         const char *opts_file = git_path(SEQ_OPTS_FILE);
 780
 781         if (opts->no_commit)
 782                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 783         if (opts->edit)
 784                 git_config_set_in_file(opts_file, "options.edit", "true");
 785         if (opts->signoff)
 786                 git_config_set_in_file(opts_file, "options.signoff", "true");
 787         if (opts->record_origin)
 788                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 789         if (opts->allow_ff)
 790                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 791         if (opts->mainline) {
 792                 struct strbuf buf = STRBUF_INIT;
 793                 strbuf_addf(&buf, "%d", opts->mainline);
 794                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 795                 strbuf_release(&buf);
 796         }
 797         if (opts->strategy)
 798                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 799         if (opts->xopts) {
 800                 int i;
 801                 for (i = 0; i < opts->xopts_nr; i++)
 802                         git_config_set_multivar_in_file(opts_file,
 803                                                         "options.strategy-option",
 804                                                         opts->xopts[i], "^$", 0);
 805         }
 806 }
 807
 808 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
 809 {
 810         struct commit_list *cur;
 811         int res;
 812
 813         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 814         if (opts->allow_ff)
 815                 assert(!(opts->signoff || opts->no_commit ||
 816                                 opts->record_origin || opts->edit));
 817         read_and_refresh_cache(opts);
 818
 819         for (cur = todo_list; cur; cur = cur->next) {
 820                 save_todo(cur, opts);
 821                 res = do_pick_commit(cur->item, opts);
 822                 if (res)
 823                         return res;
 824         }
 825
 826         /*
 827          * Sequence of picks finished successfully; cleanup by
 828          * removing the .git/sequencer directory
 829          */
 830         remove_sequencer_state();
 831         return 0;
 832 }
 833
 834 static int continue_single_pick(void)
 835 {
 836         const char *argv[] = { "commit", NULL };
 837
 838         if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
 839             !file_exists(git_path("REVERT_HEAD")))
 840                 return error(_("no cherry-pick or revert in progress"));
 841         return run_command_v_opt(argv, RUN_GIT_CMD);
 842 }
 843
 844 static int sequencer_continue(struct replay_opts *opts)
 845 {
 846         struct commit_list *todo_list = NULL;
 847
 848         if (!file_exists(git_path(SEQ_TODO_FILE)))
 849                 return continue_single_pick();
 850         read_populate_opts(&opts);
 851         read_populate_todo(&todo_list, opts);
 852
 853         /* Verify that the conflict has been resolved */
 854         if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
 855             file_exists(git_path("REVERT_HEAD"))) {
 856                 int ret = continue_single_pick();
 857                 if (ret)
 858                         return ret;
 859         }
 860         if (index_differs_from("HEAD", 0))
 861                 return error_dirty_index(opts);
 862         todo_list = todo_list->next;
 863         return pick_commits(todo_list, opts);
 864 }
 865
 866 static int single_pick(struct commit *cmit, struct replay_opts *opts)
 867 {
 868         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 869         return do_pick_commit(cmit, opts);
 870 }
 871
 872 int sequencer_pick_revisions(struct replay_opts *opts)
 873 {
 874         struct commit_list *todo_list = NULL;
 875         unsigned char sha1[20];
 876
 877         if (opts->subcommand == REPLAY_NONE)
 878                 assert(opts->revs);
 879
 880         read_and_refresh_cache(opts);
 881
 882         /*
 883          * Decide what to do depending on the arguments; a fresh
 884          * cherry-pick should be handled differently from an existing
 885          * one that is being continued
 886          */
 887         if (opts->subcommand == REPLAY_REMOVE_STATE) {
 888                 remove_sequencer_state();
 889                 return 0;
 890         }
 891         if (opts->subcommand == REPLAY_ROLLBACK)
 892                 return sequencer_rollback(opts);
 893         if (opts->subcommand == REPLAY_CONTINUE)
 894                 return sequencer_continue(opts);
 895
 896         /*
 897          * If we were called as "git cherry-pick <commit>", just
 898          * cherry-pick/revert it, set CHERRY_PICK_HEAD /
 899          * REVERT_HEAD, and don't touch the sequencer state.
 900          * This means it is possible to cherry-pick in the middle
 901          * of a cherry-pick sequence.
 902          */
 903         if (opts->revs->cmdline.nr == 1 &&
 904             opts->revs->cmdline.rev->whence == REV_CMD_REV &&
 905             opts->revs->no_walk &&
 906             !opts->revs->cmdline.rev->flags) {
 907                 struct commit *cmit;
 908                 if (prepare_revision_walk(opts->revs))
 909                         die(_("revision walk setup failed"));
 910                 cmit = get_revision(opts->revs);
 911                 if (!cmit || get_revision(opts->revs))
 912                         die("BUG: expected exactly one commit from walk");
 913                 return single_pick(cmit, opts);
 914         }
 915
 916         /*
 917          * Start a new cherry-pick/ revert sequence; but
 918          * first, make sure that an existing one isn't in
 919          * progress
 920          */
 921
 922         walk_revs_populate_todo(&todo_list, opts);
 923         if (create_seq_dir() < 0)
 924                 return -1;
 925         if (get_sha1("HEAD", sha1)) {
 926                 if (opts->action == REPLAY_REVERT)
 927                         return error(_("Can't revert as initial commit"));
 928                 return error(_("Can't cherry-pick into empty head"));
 929         }
 930         save_head(sha1_to_hex(sha1));
 931         save_opts(opts);
 932         return pick_commits(todo_list, opts);
 933 }