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 static void clear_commit_marks_1(struct commit_list **plist,
 425                                  struct commit *commit, unsigned int mark)
 426 {
 427         while (commit) {
 428                 struct commit_list *parents;
 429
 430                 if (!(mark & commit->object.flags))
 431                         return;
 432
 433                 commit->object.flags &= ~mark;
 434
 435                 parents = commit->parents;
 436                 if (!parents)
 437                         return;
 438
 439                 while ((parents = parents->next))
 440                         commit_list_insert(parents->item, plist);
 441
 442                 commit = commit->parents->item;
 443         }
 444 }
 445
 446 void clear_commit_marks(struct commit *commit, unsigned int mark)
 447 {
 448         struct commit_list *list = NULL;
 449         commit_list_insert(commit, &list);
 450         while (list)
 451                 clear_commit_marks_1(&list, pop_commit(&list), mark);
 452 }
 453
 454 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 455 {
 456         struct object *object;
 457         struct commit *commit;
 458         unsigned int i;
 459
 460         for (i = 0; i < a->nr; i++) {
 461                 object = a->objects[i].item;
 462                 commit = lookup_commit_reference_gently(object->sha1, 1);
 463                 if (commit)
 464                         clear_commit_marks(commit, mark);
 465         }
 466 }
 467
 468 struct commit *pop_commit(struct commit_list **stack)
 469 {
 470         struct commit_list *top = *stack;
 471         struct commit *item = top ? top->item : NULL;
 472
 473         if (top) {
 474                 *stack = top->next;
 475                 free(top);
 476         }
 477         return item;
 478 }
 479
 480 /*
 481  * Performs an in-place topological sort on the list supplied.
 482  */
 483 void sort_in_topological_order(struct commit_list ** list, int lifo)
 484 {
 485         struct commit_list *next, *orig = *list;
 486         struct commit_list *work, **insert;
 487         struct commit_list **pptr;
 488
 489         if (!orig)
 490                 return;
 491         *list = NULL;
 492
 493         /* Mark them and clear the indegree */
 494         for (next = orig; next; next = next->next) {
 495                 struct commit *commit = next->item;
 496                 commit->indegree = 1;
 497         }
 498
 499         /* update the indegree */
 500         for (next = orig; next; next = next->next) {
 501                 struct commit_list * parents = next->item->parents;
 502                 while (parents) {
 503                         struct commit *parent = parents->item;
 504
 505                         if (parent->indegree)
 506                                 parent->indegree++;
 507                         parents = parents->next;
 508                 }
 509         }
 510
 511         /*
 512          * find the tips
 513          *
 514          * tips are nodes not reachable from any other node in the list
 515          *
 516          * the tips serve as a starting set for the work queue.
 517          */
 518         work = NULL;
 519         insert = &work;
 520         for (next = orig; next; next = next->next) {
 521                 struct commit *commit = next->item;
 522
 523                 if (commit->indegree == 1)
 524                         insert = &commit_list_insert(commit, insert)->next;
 525         }
 526
 527         /* process the list in topological order */
 528         if (!lifo)
 529                 commit_list_sort_by_date(&work);
 530
 531         pptr = list;
 532         *list = NULL;
 533         while (work) {
 534                 struct commit *commit;
 535                 struct commit_list *parents, *work_item;
 536
 537                 work_item = work;
 538                 work = work_item->next;
 539                 work_item->next = NULL;
 540
 541                 commit = work_item->item;
 542                 for (parents = commit->parents; parents ; parents = parents->next) {
 543                         struct commit *parent = parents->item;
 544
 545                         if (!parent->indegree)
 546                                 continue;
 547
 548                         /*
 549                          * parents are only enqueued for emission
 550                          * when all their children have been emitted thereby
 551                          * guaranteeing topological order.
 552                          */
 553                         if (--parent->indegree == 1) {
 554                                 if (!lifo)
 555                                         commit_list_insert_by_date(parent, &work);
 556                                 else
 557                                         commit_list_insert(parent, &work);
 558                         }
 559                 }
 560                 /*
 561                  * work_item is a commit all of whose children
 562                  * have already been emitted. we can emit it now.
 563                  */
 564                 commit->indegree = 0;
 565                 *pptr = work_item;
 566                 pptr = &work_item->next;
 567         }
 568 }
 569
 570 /* merge-base stuff */
 571
 572 /* bits #0..15 in revision.h */
 573 #define PARENT1         (1u<<16)
 574 #define PARENT2         (1u<<17)
 575 #define STALE           (1u<<18)
 576 #define RESULT          (1u<<19)
 577
 578 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 579
 580 static struct commit *interesting(struct commit_list *list)
 581 {
 582         while (list) {
 583                 struct commit *commit = list->item;
 584                 list = list->next;
 585                 if (commit->object.flags & STALE)
 586                         continue;
 587                 return commit;
 588         }
 589         return NULL;
 590 }
 591
 592 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 593 {
 594         struct commit_list *list = NULL;
 595         struct commit_list *result = NULL;
 596         int i;
 597
 598         for (i = 0; i < n; i++) {
 599                 if (one == twos[i])
 600                         /*
 601                          * We do not mark this even with RESULT so we do not
 602                          * have to clean it up.
 603                          */
 604                         return commit_list_insert(one, &result);
 605         }
 606
 607         if (parse_commit(one))
 608                 return NULL;
 609         for (i = 0; i < n; i++) {
 610                 if (parse_commit(twos[i]))
 611                         return NULL;
 612         }
 613
 614         one->object.flags |= PARENT1;
 615         commit_list_insert_by_date(one, &list);
 616         for (i = 0; i < n; i++) {
 617                 twos[i]->object.flags |= PARENT2;
 618                 commit_list_insert_by_date(twos[i], &list);
 619         }
 620
 621         while (interesting(list)) {
 622                 struct commit *commit;
 623                 struct commit_list *parents;
 624                 struct commit_list *next;
 625                 int flags;
 626
 627                 commit = list->item;
 628                 next = list->next;
 629                 free(list);
 630                 list = next;
 631
 632                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 633                 if (flags == (PARENT1 | PARENT2)) {
 634                         if (!(commit->object.flags & RESULT)) {
 635                                 commit->object.flags |= RESULT;
 636                                 commit_list_insert_by_date(commit, &result);
 637                         }
 638                         /* Mark parents of a found merge stale */
 639                         flags |= STALE;
 640                 }
 641                 parents = commit->parents;
 642                 while (parents) {
 643                         struct commit *p = parents->item;
 644                         parents = parents->next;
 645                         if ((p->object.flags & flags) == flags)
 646                                 continue;
 647                         if (parse_commit(p))
 648                                 return NULL;
 649                         p->object.flags |= flags;
 650                         commit_list_insert_by_date(p, &list);
 651                 }
 652         }
 653
 654         /* Clean up the result to remove stale ones */
 655         free_commit_list(list);
 656         list = result; result = NULL;
 657         while (list) {
 658                 struct commit_list *next = list->next;
 659                 if (!(list->item->object.flags & STALE))
 660                         commit_list_insert_by_date(list->item, &result);
 661                 free(list);
 662                 list = next;
 663         }
 664         return result;
 665 }
 666
 667 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 668 {
 669         struct commit_list *i, *j, *k, *ret = NULL;
 670         struct commit_list **pptr = &ret;
 671
 672         for (i = in; i; i = i->next) {
 673                 if (!ret)
 674                         pptr = &commit_list_insert(i->item, pptr)->next;
 675                 else {
 676                         struct commit_list *new = NULL, *end = NULL;
 677
 678                         for (j = ret; j; j = j->next) {
 679                                 struct commit_list *bases;
 680                                 bases = get_merge_bases(i->item, j->item, 1);
 681                                 if (!new)
 682                                         new = bases;
 683                                 else
 684                                         end->next = bases;
 685                                 for (k = bases; k; k = k->next)
 686                                         end = k;
 687                         }
 688                         ret = new;
 689                 }
 690         }
 691         return ret;
 692 }
 693
 694 struct commit_list *get_merge_bases_many(struct commit *one,
 695                                          int n,
 696                                          struct commit **twos,
 697                                          int cleanup)
 698 {
 699         struct commit_list *list;
 700         struct commit **rslt;
 701         struct commit_list *result;
 702         int cnt, i, j;
 703
 704         result = merge_bases_many(one, n, twos);
 705         for (i = 0; i < n; i++) {
 706                 if (one == twos[i])
 707                         return result;
 708         }
 709         if (!result || !result->next) {
 710                 if (cleanup) {
 711                         clear_commit_marks(one, all_flags);
 712                         for (i = 0; i < n; i++)
 713                                 clear_commit_marks(twos[i], all_flags);
 714                 }
 715                 return result;
 716         }
 717
 718         /* There are more than one */
 719         cnt = 0;
 720         list = result;
 721         while (list) {
 722                 list = list->next;
 723                 cnt++;
 724         }
 725         rslt = xcalloc(cnt, sizeof(*rslt));
 726         for (list = result, i = 0; list; list = list->next)
 727                 rslt[i++] = list->item;
 728         free_commit_list(result);
 729
 730         clear_commit_marks(one, all_flags);
 731         for (i = 0; i < n; i++)
 732                 clear_commit_marks(twos[i], all_flags);
 733         for (i = 0; i < cnt - 1; i++) {
 734                 for (j = i+1; j < cnt; j++) {
 735                         if (!rslt[i] || !rslt[j])
 736                                 continue;
 737                         result = merge_bases_many(rslt[i], 1, &rslt[j]);
 738                         clear_commit_marks(rslt[i], all_flags);
 739                         clear_commit_marks(rslt[j], all_flags);
 740                         for (list = result; list; list = list->next) {
 741                                 if (rslt[i] == list->item)
 742                                         rslt[i] = NULL;
 743                                 if (rslt[j] == list->item)
 744                                         rslt[j] = NULL;
 745                         }
 746                 }
 747         }
 748
 749         /* Surviving ones in rslt[] are the independent results */
 750         result = NULL;
 751         for (i = 0; i < cnt; i++) {
 752                 if (rslt[i])
 753                         commit_list_insert_by_date(rslt[i], &result);
 754         }
 755         free(rslt);
 756         return result;
 757 }
 758
 759 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 760                                     int cleanup)
 761 {
 762         return get_merge_bases_many(one, 1, &two, cleanup);
 763 }
 764
 765 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 766 {
 767         if (!with_commit)
 768                 return 1;
 769         while (with_commit) {
 770                 struct commit *other;
 771
 772                 other = with_commit->item;
 773                 with_commit = with_commit->next;
 774                 if (in_merge_bases(other, &commit, 1))
 775                         return 1;
 776         }
 777         return 0;
 778 }
 779
 780 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 781 {
 782         struct commit_list *bases, *b;
 783         int ret = 0;
 784
 785         if (num == 1)
 786                 bases = get_merge_bases(commit, *reference, 1);
 787         else
 788                 die("not yet");
 789         for (b = bases; b; b = b->next) {
 790                 if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 791                         ret = 1;
 792                         break;
 793                 }
 794         }
 795
 796         free_commit_list(bases);
 797         return ret;
 798 }
 799
 800 struct commit_list *reduce_heads(struct commit_list *heads)
 801 {
 802         struct commit_list *p;
 803         struct commit_list *result = NULL, **tail = &result;
 804         struct commit **other;
 805         size_t num_head, num_other;
 806
 807         if (!heads)
 808                 return NULL;
 809
 810         /* Avoid unnecessary reallocations */
 811         for (p = heads, num_head = 0; p; p = p->next)
 812                 num_head++;
 813         other = xcalloc(sizeof(*other), num_head);
 814
 815         /* For each commit, see if it can be reached by others */
 816         for (p = heads; p; p = p->next) {
 817                 struct commit_list *q, *base;
 818
 819                 /* Do we already have this in the result? */
 820                 for (q = result; q; q = q->next)
 821                         if (p->item == q->item)
 822                                 break;
 823                 if (q)
 824                         continue;
 825
 826                 num_other = 0;
 827                 for (q = heads; q; q = q->next) {
 828                         if (p->item == q->item)
 829                                 continue;
 830                         other[num_other++] = q->item;
 831                 }
 832                 if (num_other)
 833                         base = get_merge_bases_many(p->item, num_other, other, 1);
 834                 else
 835                         base = NULL;
 836                 /*
 837                  * If p->item does not have anything common with other
 838                  * commits, there won't be any merge base.  If it is
 839                  * reachable from some of the others, p->item will be
 840                  * the merge base.  If its history is connected with
 841                  * others, but p->item is not reachable by others, we
 842                  * will get something other than p->item back.
 843                  */
 844                 if (!base || (base->item != p->item))
 845                         tail = &(commit_list_insert(p->item, tail)->next);
 846                 free_commit_list(base);
 847         }
 848         free(other);
 849         return result;
 850 }
 851
 852 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 853 {
 854         struct merge_remote_desc *desc;
 855         struct commit_extra_header *mergetag;
 856         char *buf;
 857         unsigned long size, len;
 858         enum object_type type;
 859
 860         desc = merge_remote_util(parent);
 861         if (!desc || !desc->obj)
 862                 return;
 863         buf = read_sha1_file(desc->obj->sha1, &type, &size);
 864         if (!buf || type != OBJ_TAG)
 865                 goto free_return;
 866         len = parse_signature(buf, size);
 867         if (size == len)
 868                 goto free_return;
 869         /*
 870          * We could verify this signature and either omit the tag when
 871          * it does not validate, but the integrator may not have the
 872          * public key of the signer of the tag he is merging, while a
 873          * later auditor may have it while auditing, so let's not run
 874          * verify-signed-buffer here for now...
 875          *
 876          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 877          *      warn("warning: signed tag unverified.");
 878          */
 879         mergetag = xcalloc(1, sizeof(*mergetag));
 880         mergetag->key = xstrdup("mergetag");
 881         mergetag->value = buf;
 882         mergetag->len = size;
 883
 884         **tail = mergetag;
 885         *tail = &mergetag->next;
 886         return;
 887
 888 free_return:
 889         free(buf);
 890 }
 891
 892 void append_merge_tag_headers(struct commit_list *parents,
 893                               struct commit_extra_header ***tail)
 894 {
 895         while (parents) {
 896                 struct commit *parent = parents->item;
 897                 handle_signed_tag(parent, tail);
 898                 parents = parents->next;
 899         }
 900 }
 901
 902 static void add_extra_header(struct strbuf *buffer,
 903                              struct commit_extra_header *extra)
 904 {
 905         strbuf_addstr(buffer, extra->key);
 906         if (extra->len)
 907                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
 908         else
 909                 strbuf_addch(buffer, '\n');
 910 }
 911
 912 struct commit_extra_header *read_commit_extra_headers(struct commit *commit)
 913 {
 914         struct commit_extra_header *extra = NULL;
 915         unsigned long size;
 916         enum object_type type;
 917         char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
 918         if (buffer && type == OBJ_COMMIT)
 919                 extra = read_commit_extra_header_lines(buffer, size);
 920         free(buffer);
 921         return extra;
 922 }
 923
 924 static inline int standard_header_field(const char *field, size_t len)
 925 {
 926         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
 927                 (len == 6 && !memcmp(field, "parent ", 7)) ||
 928                 (len == 6 && !memcmp(field, "author ", 7)) ||
 929                 (len == 9 && !memcmp(field, "committer ", 10)) ||
 930                 (len == 8 && !memcmp(field, "encoding ", 9)));
 931 }
 932
 933 struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size)
 934 {
 935         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
 936         const char *line, *next, *eof, *eob;
 937         struct strbuf buf = STRBUF_INIT;
 938
 939         for (line = buffer, eob = line + size;
 940              line < eob && *line != '\n';
 941              line = next) {
 942                 next = memchr(line, '\n', eob - line);
 943                 next = next ? next + 1 : eob;
 944                 if (*line == ' ') {
 945                         /* continuation */
 946                         if (it)
 947                                 strbuf_add(&buf, line + 1, next - (line + 1));
 948                         continue;
 949                 }
 950                 if (it)
 951                         it->value = strbuf_detach(&buf, &it->len);
 952                 strbuf_reset(&buf);
 953                 it = NULL;
 954
 955                 eof = strchr(line, ' ');
 956                 if (next <= eof)
 957                         eof = next;
 958
 959                 if (standard_header_field(line, eof - line))
 960                         continue;
 961
 962                 it = xcalloc(1, sizeof(*it));
 963                 it->key = xmemdupz(line, eof-line);
 964                 *tail = it;
 965                 tail = &it->next;
 966                 if (eof + 1 < next)
 967                         strbuf_add(&buf, eof + 1, next - (eof + 1));
 968         }
 969         if (it)
 970                 it->value = strbuf_detach(&buf, &it->len);
 971         return extra;
 972 }
 973
 974 void free_commit_extra_headers(struct commit_extra_header *extra)
 975 {
 976         while (extra) {
 977                 struct commit_extra_header *next = extra->next;
 978                 free(extra->key);
 979                 free(extra->value);
 980                 free(extra);
 981                 extra = next;
 982         }
 983 }
 984
 985 int commit_tree(const struct strbuf *msg, unsigned char *tree,
 986                 struct commit_list *parents, unsigned char *ret,
 987                 const char *author)
 988 {
 989         struct commit_extra_header *extra = NULL, **tail = &extra;
 990         int result;
 991
 992         append_merge_tag_headers(parents, &tail);
 993         result = commit_tree_extended(msg, tree, parents, ret, author, extra);
 994         free_commit_extra_headers(extra);
 995         return result;
 996 }
 997
 998 static const char commit_utf8_warn[] =
 999 "Warning: commit message does not conform to UTF-8.\n"
1000 "You may want to amend it after fixing the message, or set the config\n"
1001 "variable i18n.commitencoding to the encoding your project uses.\n";
1002
1003 int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1004                          struct commit_list *parents, unsigned char *ret,
1005                          const char *author, struct commit_extra_header *extra)
1006 {
1007         int result;
1008         int encoding_is_utf8;
1009         struct strbuf buffer;
1010
1011         assert_sha1_type(tree, OBJ_TREE);
1012
1013         if (memchr(msg->buf, '\0', msg->len))
1014                 return error("a NUL byte in commit log message not allowed.");
1015
1016         /* Not having i18n.commitencoding is the same as having utf-8 */
1017         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1018
1019         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1020         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1021
1022         /*
1023          * NOTE! This ordering means that the same exact tree merged with a
1024          * different order of parents will be a _different_ changeset even
1025          * if everything else stays the same.
1026          */
1027         while (parents) {
1028                 struct commit_list *next = parents->next;
1029                 struct commit *parent = parents->item;
1030
1031                 strbuf_addf(&buffer, "parent %s\n",
1032                             sha1_to_hex(parent->object.sha1));
1033                 free(parents);
1034                 parents = next;
1035         }
1036
1037         /* Person/date information */
1038         if (!author)
1039                 author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1040         strbuf_addf(&buffer, "author %s\n", author);
1041         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1042         if (!encoding_is_utf8)
1043                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1044
1045         while (extra) {
1046                 add_extra_header(&buffer, extra);
1047                 extra = extra->next;
1048         }
1049         strbuf_addch(&buffer, '\n');
1050
1051         /* And add the comment */
1052         strbuf_addbuf(&buffer, msg);
1053
1054         /* And check the encoding */
1055         if (encoding_is_utf8 && !is_utf8(buffer.buf))
1056                 fprintf(stderr, commit_utf8_warn);
1057
1058         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1059         strbuf_release(&buffer);
1060         return result;
1061 }
1062
1063 struct commit *get_merge_parent(const char *name)
1064 {
1065         struct object *obj;
1066         struct commit *commit;
1067         unsigned char sha1[20];
1068         if (get_sha1(name, sha1))
1069                 return NULL;
1070         obj = parse_object(sha1);
1071         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1072         if (commit && !commit->util) {
1073                 struct merge_remote_desc *desc;
1074                 desc = xmalloc(sizeof(*desc));
1075                 desc->obj = obj;
1076                 desc->name = strdup(name);
1077                 commit->util = desc;
1078         }
1079         return commit;
1080 }