commit.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "pkt-line.h"
   5 #include "utf8.h"
   6 #include "diff.h"
   7 #include "revision.h"
   8 #include "notes.h"
   9
  10 int save_commit_buffer = 1;
  11
  12 const char *commit_type = "commit";
  13
  14 static struct commit *check_commit(struct object *obj,
  15                                    const unsigned char *sha1,
  16                                    int quiet)
  17 {
  18         if (obj->type != OBJ_COMMIT) {
  19                 if (!quiet)
  20                         error("Object %s is a %s, not a commit",
  21                               sha1_to_hex(sha1), typename(obj->type));
  22                 return NULL;
  23         }
  24         return (struct commit *) obj;
  25 }
  26
  27 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  28                                               int quiet)
  29 {
  30         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  31
  32         if (!obj)
  33                 return NULL;
  34         return check_commit(obj, sha1, quiet);
  35 }
  36
  37 struct commit *lookup_commit_reference(const unsigned char *sha1)
  38 {
  39         return lookup_commit_reference_gently(sha1, 0);
  40 }
  41
  42 struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  43 {
  44         struct commit *c = lookup_commit_reference(sha1);
  45         if (!c)
  46                 die(_("could not parse %s"), ref_name);
  47         if (hashcmp(sha1, c->object.sha1)) {
  48                 warning(_("%s %s is not a commit!"),
  49                         ref_name, sha1_to_hex(sha1));
  50         }
  51         return c;
  52 }
  53
  54 struct commit *lookup_commit(const unsigned char *sha1)
  55 {
  56         struct object *obj = lookup_object(sha1);
  57         if (!obj)
  58                 return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  59         if (!obj->type)
  60                 obj->type = OBJ_COMMIT;
  61         return check_commit(obj, sha1, 0);
  62 }
  63
  64 struct commit *lookup_commit_reference_by_name(const char *name)
  65 {
  66         unsigned char sha1[20];
  67         struct commit *commit;
  68
  69         if (get_sha1(name, sha1))
  70                 return NULL;
  71         commit = lookup_commit_reference(sha1);
  72         if (!commit || parse_commit(commit))
  73                 return NULL;
  74         return commit;
  75 }
  76
  77 static unsigned long parse_commit_date(const char *buf, const char *tail)
  78 {
  79         const char *dateptr;
  80
  81         if (buf + 6 >= tail)
  82                 return 0;
  83         if (memcmp(buf, "author", 6))
  84                 return 0;
  85         while (buf < tail && *buf++ != '\n')
  86                 /* nada */;
  87         if (buf + 9 >= tail)
  88                 return 0;
  89         if (memcmp(buf, "committer", 9))
  90                 return 0;
  91         while (buf < tail && *buf++ != '>')
  92                 /* nada */;
  93         if (buf >= tail)
  94                 return 0;
  95         dateptr = buf;
  96         while (buf < tail && *buf++ != '\n')
  97                 /* nada */;
  98         if (buf >= tail)
  99                 return 0;
 100         /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 101         return strtoul(dateptr, NULL, 10);
 102 }
 103
 104 static struct commit_graft **commit_graft;
 105 static int commit_graft_alloc, commit_graft_nr;
 106
 107 static int commit_graft_pos(const unsigned char *sha1)
 108 {
 109         int lo, hi;
 110         lo = 0;
 111         hi = commit_graft_nr;
 112         while (lo < hi) {
 113                 int mi = (lo + hi) / 2;
 114                 struct commit_graft *graft = commit_graft[mi];
 115                 int cmp = hashcmp(sha1, graft->sha1);
 116                 if (!cmp)
 117                         return mi;
 118                 if (cmp < 0)
 119                         hi = mi;
 120                 else
 121                         lo = mi + 1;
 122         }
 123         return -lo - 1;
 124 }
 125
 126 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 127 {
 128         int pos = commit_graft_pos(graft->sha1);
 129
 130         if (0 <= pos) {
 131                 if (ignore_dups)
 132                         free(graft);
 133                 else {
 134                         free(commit_graft[pos]);
 135                         commit_graft[pos] = graft;
 136                 }
 137                 return 1;
 138         }
 139         pos = -pos - 1;
 140         if (commit_graft_alloc <= ++commit_graft_nr) {
 141                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 142                 commit_graft = xrealloc(commit_graft,
 143                                         sizeof(*commit_graft) *
 144                                         commit_graft_alloc);
 145         }
 146         if (pos < commit_graft_nr)
 147                 memmove(commit_graft + pos + 1,
 148                         commit_graft + pos,
 149                         (commit_graft_nr - pos - 1) *
 150                         sizeof(*commit_graft));
 151         commit_graft[pos] = graft;
 152         return 0;
 153 }
 154
 155 struct commit_graft *read_graft_line(char *buf, int len)
 156 {
 157         /* The format is just "Commit Parent1 Parent2 ...\n" */
 158         int i;
 159         struct commit_graft *graft = NULL;
 160
 161         while (len && isspace(buf[len-1]))
 162                 buf[--len] = '\0';
 163         if (buf[0] == '#' || buf[0] == '\0')
 164                 return NULL;
 165         if ((len + 1) % 41)
 166                 goto bad_graft_data;
 167         i = (len + 1) / 41 - 1;
 168         graft = xmalloc(sizeof(*graft) + 20 * i);
 169         graft->nr_parent = i;
 170         if (get_sha1_hex(buf, graft->sha1))
 171                 goto bad_graft_data;
 172         for (i = 40; i < len; i += 41) {
 173                 if (buf[i] != ' ')
 174                         goto bad_graft_data;
 175                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 176                         goto bad_graft_data;
 177         }
 178         return graft;
 179
 180 bad_graft_data:
 181         error("bad graft data: %s", buf);
 182         free(graft);
 183         return NULL;
 184 }
 185
 186 static int read_graft_file(const char *graft_file)
 187 {
 188         FILE *fp = fopen(graft_file, "r");
 189         char buf[1024];
 190         if (!fp)
 191                 return -1;
 192         while (fgets(buf, sizeof(buf), fp)) {
 193                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 194                 int len = strlen(buf);
 195                 struct commit_graft *graft = read_graft_line(buf, len);
 196                 if (!graft)
 197                         continue;
 198                 if (register_commit_graft(graft, 1))
 199                         error("duplicate graft data: %s", buf);
 200         }
 201         fclose(fp);
 202         return 0;
 203 }
 204
 205 static void prepare_commit_graft(void)
 206 {
 207         static int commit_graft_prepared;
 208         char *graft_file;
 209
 210         if (commit_graft_prepared)
 211                 return;
 212         graft_file = get_graft_file();
 213         read_graft_file(graft_file);
 214         /* make sure shallows are read */
 215         is_repository_shallow();
 216         commit_graft_prepared = 1;
 217 }
 218
 219 struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 220 {
 221         int pos;
 222         prepare_commit_graft();
 223         pos = commit_graft_pos(sha1);
 224         if (pos < 0)
 225                 return NULL;
 226         return commit_graft[pos];
 227 }
 228
 229 int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 230 {
 231         int i, ret;
 232         for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 233                 ret = fn(commit_graft[i], cb_data);
 234         return ret;
 235 }
 236
 237 int unregister_shallow(const unsigned char *sha1)
 238 {
 239         int pos = commit_graft_pos(sha1);
 240         if (pos < 0)
 241                 return -1;
 242         if (pos + 1 < commit_graft_nr)
 243                 memmove(commit_graft + pos, commit_graft + pos + 1,
 244                                 sizeof(struct commit_graft *)
 245                                 * (commit_graft_nr - pos - 1));
 246         commit_graft_nr--;
 247         return 0;
 248 }
 249
 250 int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 251 {
 252         const char *tail = buffer;
 253         const char *bufptr = buffer;
 254         unsigned char parent[20];
 255         struct commit_list **pptr;
 256         struct commit_graft *graft;
 257
 258         if (item->object.parsed)
 259                 return 0;
 260         item->object.parsed = 1;
 261         tail += size;
 262         if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 263                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 264         if (get_sha1_hex(bufptr + 5, parent) < 0)
 265                 return error("bad tree pointer in commit %s",
 266                              sha1_to_hex(item->object.sha1));
 267         item->tree = lookup_tree(parent);
 268         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 269         pptr = &item->parents;
 270
 271         graft = lookup_commit_graft(item->object.sha1);
 272         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 273                 struct commit *new_parent;
 274
 275                 if (tail <= bufptr + 48 ||
 276                     get_sha1_hex(bufptr + 7, parent) ||
 277                     bufptr[47] != '\n')
 278                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 279                 bufptr += 48;
 280                 /*
 281                  * The clone is shallow if nr_parent < 0, and we must
 282                  * not traverse its real parents even when we unhide them.
 283                  */
 284                 if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 285                         continue;
 286                 new_parent = lookup_commit(parent);
 287                 if (new_parent)
 288                         pptr = &commit_list_insert(new_parent, pptr)->next;
 289         }
 290         if (graft) {
 291                 int i;
 292                 struct commit *new_parent;
 293                 for (i = 0; i < graft->nr_parent; i++) {
 294                         new_parent = lookup_commit(graft->parent[i]);
 295                         if (!new_parent)
 296                                 continue;
 297                         pptr = &commit_list_insert(new_parent, pptr)->next;
 298                 }
 299         }
 300         item->date = parse_commit_date(bufptr, tail);
 301
 302         return 0;
 303 }
 304
 305 int parse_commit(struct commit *item)
 306 {
 307         enum object_type type;
 308         void *buffer;
 309         unsigned long size;
 310         int ret;
 311
 312         if (!item)
 313                 return -1;
 314         if (item->object.parsed)
 315                 return 0;
 316         buffer = read_sha1_file(item->object.sha1, &type, &size);
 317         if (!buffer)
 318                 return error("Could not read %s",
 319                              sha1_to_hex(item->object.sha1));
 320         if (type != OBJ_COMMIT) {
 321                 free(buffer);
 322                 return error("Object %s not a commit",
 323                              sha1_to_hex(item->object.sha1));
 324         }
 325         ret = parse_commit_buffer(item, buffer, size);
 326         if (save_commit_buffer && !ret) {
 327                 item->buffer = buffer;
 328                 return 0;
 329         }
 330         free(buffer);
 331         return ret;
 332 }
 333
 334 int find_commit_subject(const char *commit_buffer, const char **subject)
 335 {
 336         const char *eol;
 337         const char *p = commit_buffer;
 338
 339         while (*p && (*p != '\n' || p[1] != '\n'))
 340                 p++;
 341         if (*p) {
 342                 p += 2;
 343                 for (eol = p; *eol && *eol != '\n'; eol++)
 344                         ; /* do nothing */
 345         } else
 346                 eol = p;
 347
 348         *subject = p;
 349
 350         return eol - p;
 351 }
 352
 353 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 354 {
 355         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 356         new_list->item = item;
 357         new_list->next = *list_p;
 358         *list_p = new_list;
 359         return new_list;
 360 }
 361
 362 unsigned commit_list_count(const struct commit_list *l)
 363 {
 364         unsigned c = 0;
 365         for (; l; l = l->next )
 366                 c++;
 367         return c;
 368 }
 369
 370 void free_commit_list(struct commit_list *list)
 371 {
 372         while (list) {
 373                 struct commit_list *temp = list;
 374                 list = temp->next;
 375                 free(temp);
 376         }
 377 }
 378
 379 struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 380 {
 381         struct commit_list **pp = list;
 382         struct commit_list *p;
 383         while ((p = *pp) != NULL) {
 384                 if (p->item->date < item->date) {
 385                         break;
 386                 }
 387                 pp = &p->next;
 388         }
 389         return commit_list_insert(item, pp);
 390 }
 391
 392
 393 void commit_list_sort_by_date(struct commit_list **list)
 394 {
 395         struct commit_list *ret = NULL;
 396         while (*list) {
 397                 commit_list_insert_by_date((*list)->item, &ret);
 398                 *list = (*list)->next;
 399         }
 400         *list = ret;
 401 }
 402
 403 struct commit *pop_most_recent_commit(struct commit_list **list,
 404                                       unsigned int mark)
 405 {
 406         struct commit *ret = (*list)->item;
 407         struct commit_list *parents = ret->parents;
 408         struct commit_list *old = *list;
 409
 410         *list = (*list)->next;
 411         free(old);
 412
 413         while (parents) {
 414                 struct commit *commit = parents->item;
 415                 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 416                         commit->object.flags |= mark;
 417                         commit_list_insert_by_date(commit, list);
 418                 }
 419                 parents = parents->next;
 420         }
 421         return ret;
 422 }
 423
 424 void clear_commit_marks(struct commit *commit, unsigned int mark)
 425 {
 426         while (commit) {
 427                 struct commit_list *parents;
 428
 429                 if (!(mark & commit->object.flags))
 430                         return;
 431
 432                 commit->object.flags &= ~mark;
 433
 434                 parents = commit->parents;
 435                 if (!parents)
 436                         return;
 437
 438                 while ((parents = parents->next))
 439                         clear_commit_marks(parents->item, mark);
 440
 441                 commit = commit->parents->item;
 442         }
 443 }
 444
 445 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 446 {
 447         struct object *object;
 448         struct commit *commit;
 449         unsigned int i;
 450
 451         for (i = 0; i < a->nr; i++) {
 452                 object = a->objects[i].item;
 453                 commit = lookup_commit_reference_gently(object->sha1, 1);
 454                 if (commit)
 455                         clear_commit_marks(commit, mark);
 456         }
 457 }
 458
 459 struct commit *pop_commit(struct commit_list **stack)
 460 {
 461         struct commit_list *top = *stack;
 462         struct commit *item = top ? top->item : NULL;
 463
 464         if (top) {
 465                 *stack = top->next;
 466                 free(top);
 467         }
 468         return item;
 469 }
 470
 471 /*
 472  * Performs an in-place topological sort on the list supplied.
 473  */
 474 void sort_in_topological_order(struct commit_list ** list, int lifo)
 475 {
 476         struct commit_list *next, *orig = *list;
 477         struct commit_list *work, **insert;
 478         struct commit_list **pptr;
 479
 480         if (!orig)
 481                 return;
 482         *list = NULL;
 483
 484         /* Mark them and clear the indegree */
 485         for (next = orig; next; next = next->next) {
 486                 struct commit *commit = next->item;
 487                 commit->indegree = 1;
 488         }
 489
 490         /* update the indegree */
 491         for (next = orig; next; next = next->next) {
 492                 struct commit_list * parents = next->item->parents;
 493                 while (parents) {
 494                         struct commit *parent = parents->item;
 495
 496                         if (parent->indegree)
 497                                 parent->indegree++;
 498                         parents = parents->next;
 499                 }
 500         }
 501
 502         /*
 503          * find the tips
 504          *
 505          * tips are nodes not reachable from any other node in the list
 506          *
 507          * the tips serve as a starting set for the work queue.
 508          */
 509         work = NULL;
 510         insert = &work;
 511         for (next = orig; next; next = next->next) {
 512                 struct commit *commit = next->item;
 513
 514                 if (commit->indegree == 1)
 515                         insert = &commit_list_insert(commit, insert)->next;
 516         }
 517
 518         /* process the list in topological order */
 519         if (!lifo)
 520                 commit_list_sort_by_date(&work);
 521
 522         pptr = list;
 523         *list = NULL;
 524         while (work) {
 525                 struct commit *commit;
 526                 struct commit_list *parents, *work_item;
 527
 528                 work_item = work;
 529                 work = work_item->next;
 530                 work_item->next = NULL;
 531
 532                 commit = work_item->item;
 533                 for (parents = commit->parents; parents ; parents = parents->next) {
 534                         struct commit *parent = parents->item;
 535
 536                         if (!parent->indegree)
 537                                 continue;
 538
 539                         /*
 540                          * parents are only enqueued for emission
 541                          * when all their children have been emitted thereby
 542                          * guaranteeing topological order.
 543                          */
 544                         if (--parent->indegree == 1) {
 545                                 if (!lifo)
 546                                         commit_list_insert_by_date(parent, &work);
 547                                 else
 548                                         commit_list_insert(parent, &work);
 549                         }
 550                 }
 551                 /*
 552                  * work_item is a commit all of whose children
 553                  * have already been emitted. we can emit it now.
 554                  */
 555                 commit->indegree = 0;
 556                 *pptr = work_item;
 557                 pptr = &work_item->next;
 558         }
 559 }
 560
 561 /* merge-base stuff */
 562
 563 /* bits #0..15 in revision.h */
 564 #define PARENT1         (1u<<16)
 565 #define PARENT2         (1u<<17)
 566 #define STALE           (1u<<18)
 567 #define RESULT          (1u<<19)
 568
 569 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 570
 571 static struct commit *interesting(struct commit_list *list)
 572 {
 573         while (list) {
 574                 struct commit *commit = list->item;
 575                 list = list->next;
 576                 if (commit->object.flags & STALE)
 577                         continue;
 578                 return commit;
 579         }
 580         return NULL;
 581 }
 582
 583 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 584 {
 585         struct commit_list *list = NULL;
 586         struct commit_list *result = NULL;
 587         int i;
 588
 589         for (i = 0; i < n; i++) {
 590                 if (one == twos[i])
 591                         /*
 592                          * We do not mark this even with RESULT so we do not
 593                          * have to clean it up.
 594                          */
 595                         return commit_list_insert(one, &result);
 596         }
 597
 598         if (parse_commit(one))
 599                 return NULL;
 600         for (i = 0; i < n; i++) {
 601                 if (parse_commit(twos[i]))
 602                         return NULL;
 603         }
 604
 605         one->object.flags |= PARENT1;
 606         commit_list_insert_by_date(one, &list);
 607         for (i = 0; i < n; i++) {
 608                 twos[i]->object.flags |= PARENT2;
 609                 commit_list_insert_by_date(twos[i], &list);
 610         }
 611
 612         while (interesting(list)) {
 613                 struct commit *commit;
 614                 struct commit_list *parents;
 615                 struct commit_list *next;
 616                 int flags;
 617
 618                 commit = list->item;
 619                 next = list->next;
 620                 free(list);
 621                 list = next;
 622
 623                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 624                 if (flags == (PARENT1 | PARENT2)) {
 625                         if (!(commit->object.flags & RESULT)) {
 626                                 commit->object.flags |= RESULT;
 627                                 commit_list_insert_by_date(commit, &result);
 628                         }
 629                         /* Mark parents of a found merge stale */
 630                         flags |= STALE;
 631                 }
 632                 parents = commit->parents;
 633                 while (parents) {
 634                         struct commit *p = parents->item;
 635                         parents = parents->next;
 636                         if ((p->object.flags & flags) == flags)
 637                                 continue;
 638                         if (parse_commit(p))
 639                                 return NULL;
 640                         p->object.flags |= flags;
 641                         commit_list_insert_by_date(p, &list);
 642                 }
 643         }
 644
 645         /* Clean up the result to remove stale ones */
 646         free_commit_list(list);
 647         list = result; result = NULL;
 648         while (list) {
 649                 struct commit_list *next = list->next;
 650                 if (!(list->item->object.flags & STALE))
 651                         commit_list_insert_by_date(list->item, &result);
 652                 free(list);
 653                 list = next;
 654         }
 655         return result;
 656 }
 657
 658 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 659 {
 660         struct commit_list *i, *j, *k, *ret = NULL;
 661         struct commit_list **pptr = &ret;
 662
 663         for (i = in; i; i = i->next) {
 664                 if (!ret)
 665                         pptr = &commit_list_insert(i->item, pptr)->next;
 666                 else {
 667                         struct commit_list *new = NULL, *end = NULL;
 668
 669                         for (j = ret; j; j = j->next) {
 670                                 struct commit_list *bases;
 671                                 bases = get_merge_bases(i->item, j->item, 1);
 672                                 if (!new)
 673                                         new = bases;
 674                                 else
 675                                         end->next = bases;
 676                                 for (k = bases; k; k = k->next)
 677                                         end = k;
 678                         }
 679                         ret = new;
 680                 }
 681         }
 682         return ret;
 683 }
 684
 685 struct commit_list *get_merge_bases_many(struct commit *one,
 686                                          int n,
 687                                          struct commit **twos,
 688                                          int cleanup)
 689 {
 690         struct commit_list *list;
 691         struct commit **rslt;
 692         struct commit_list *result;
 693         int cnt, i, j;
 694
 695         result = merge_bases_many(one, n, twos);
 696         for (i = 0; i < n; i++) {
 697                 if (one == twos[i])
 698                         return result;
 699         }
 700         if (!result || !result->next) {
 701                 if (cleanup) {
 702                         clear_commit_marks(one, all_flags);
 703                         for (i = 0; i < n; i++)
 704                                 clear_commit_marks(twos[i], all_flags);
 705                 }
 706                 return result;
 707         }
 708
 709         /* There are more than one */
 710         cnt = 0;
 711         list = result;
 712         while (list) {
 713                 list = list->next;
 714                 cnt++;
 715         }
 716         rslt = xcalloc(cnt, sizeof(*rslt));
 717         for (list = result, i = 0; list; list = list->next)
 718                 rslt[i++] = list->item;
 719         free_commit_list(result);
 720
 721         clear_commit_marks(one, all_flags);
 722         for (i = 0; i < n; i++)
 723                 clear_commit_marks(twos[i], all_flags);
 724         for (i = 0; i < cnt - 1; i++) {
 725                 for (j = i+1; j < cnt; j++) {
 726                         if (!rslt[i] || !rslt[j])
 727                                 continue;
 728                         result = merge_bases_many(rslt[i], 1, &rslt[j]);
 729                         clear_commit_marks(rslt[i], all_flags);
 730                         clear_commit_marks(rslt[j], all_flags);
 731                         for (list = result; list; list = list->next) {
 732                                 if (rslt[i] == list->item)
 733                                         rslt[i] = NULL;
 734                                 if (rslt[j] == list->item)
 735                                         rslt[j] = NULL;
 736                         }
 737                 }
 738         }
 739
 740         /* Surviving ones in rslt[] are the independent results */
 741         result = NULL;
 742         for (i = 0; i < cnt; i++) {
 743                 if (rslt[i])
 744                         commit_list_insert_by_date(rslt[i], &result);
 745         }
 746         free(rslt);
 747         return result;
 748 }
 749
 750 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 751                                     int cleanup)
 752 {
 753         return get_merge_bases_many(one, 1, &two, cleanup);
 754 }
 755
 756 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 757 {
 758         if (!with_commit)
 759                 return 1;
 760         while (with_commit) {
 761                 struct commit *other;
 762
 763                 other = with_commit->item;
 764                 with_commit = with_commit->next;
 765                 if (in_merge_bases(other, &commit, 1))
 766                         return 1;
 767         }
 768         return 0;
 769 }
 770
 771 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 772 {
 773         struct commit_list *bases, *b;
 774         int ret = 0;
 775
 776         if (num == 1)
 777                 bases = get_merge_bases(commit, *reference, 1);
 778         else
 779                 die("not yet");
 780         for (b = bases; b; b = b->next) {
 781                 if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 782                         ret = 1;
 783                         break;
 784                 }
 785         }
 786
 787         free_commit_list(bases);
 788         return ret;
 789 }
 790
 791 struct commit_list *reduce_heads(struct commit_list *heads)
 792 {
 793         struct commit_list *p;
 794         struct commit_list *result = NULL, **tail = &result;
 795         struct commit **other;
 796         size_t num_head, num_other;
 797
 798         if (!heads)
 799                 return NULL;
 800
 801         /* Avoid unnecessary reallocations */
 802         for (p = heads, num_head = 0; p; p = p->next)
 803                 num_head++;
 804         other = xcalloc(sizeof(*other), num_head);
 805
 806         /* For each commit, see if it can be reached by others */
 807         for (p = heads; p; p = p->next) {
 808                 struct commit_list *q, *base;
 809
 810                 /* Do we already have this in the result? */
 811                 for (q = result; q; q = q->next)
 812                         if (p->item == q->item)
 813                                 break;
 814                 if (q)
 815                         continue;
 816
 817                 num_other = 0;
 818                 for (q = heads; q; q = q->next) {
 819                         if (p->item == q->item)
 820                                 continue;
 821                         other[num_other++] = q->item;
 822                 }
 823                 if (num_other)
 824                         base = get_merge_bases_many(p->item, num_other, other, 1);
 825                 else
 826                         base = NULL;
 827                 /*
 828                  * If p->item does not have anything common with other
 829                  * commits, there won't be any merge base.  If it is
 830                  * reachable from some of the others, p->item will be
 831                  * the merge base.  If its history is connected with
 832                  * others, but p->item is not reachable by others, we
 833                  * will get something other than p->item back.
 834                  */
 835                 if (!base || (base->item != p->item))
 836                         tail = &(commit_list_insert(p->item, tail)->next);
 837                 free_commit_list(base);
 838         }
 839         free(other);
 840         return result;
 841 }
 842
 843 static const char commit_utf8_warn[] =
 844 "Warning: commit message does not conform to UTF-8.\n"
 845 "You may want to amend it after fixing the message, or set the config\n"
 846 "variable i18n.commitencoding to the encoding your project uses.\n";
 847
 848 int commit_tree(const char *msg, unsigned char *tree,
 849                 struct commit_list *parents, unsigned char *ret,
 850                 const char *author)
 851 {
 852         int result;
 853         int encoding_is_utf8;
 854         struct strbuf buffer;
 855
 856         assert_sha1_type(tree, OBJ_TREE);
 857
 858         /* Not having i18n.commitencoding is the same as having utf-8 */
 859         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
 860
 861         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
 862         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
 863
 864         /*
 865          * NOTE! This ordering means that the same exact tree merged with a
 866          * different order of parents will be a _different_ changeset even
 867          * if everything else stays the same.
 868          */
 869         while (parents) {
 870                 struct commit_list *next = parents->next;
 871                 strbuf_addf(&buffer, "parent %s\n",
 872                         sha1_to_hex(parents->item->object.sha1));
 873                 free(parents);
 874                 parents = next;
 875         }
 876
 877         /* Person/date information */
 878         if (!author)
 879                 author = git_author_info(IDENT_ERROR_ON_NO_NAME);
 880         strbuf_addf(&buffer, "author %s\n", author);
 881         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
 882         if (!encoding_is_utf8)
 883                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
 884         strbuf_addch(&buffer, '\n');
 885
 886         /* And add the comment */
 887         strbuf_addstr(&buffer, msg);
 888
 889         /* And check the encoding */
 890         if (encoding_is_utf8 && !is_utf8(buffer.buf))
 891                 fprintf(stderr, commit_utf8_warn);
 892
 893         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
 894         strbuf_release(&buffer);
 895         return result;
 896 }