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 #include "gpg-interface.h"
  10 #include "mergesort.h"
  11
  12 int save_commit_buffer = 1;
  13
  14 const char *commit_type = "commit";
  15
  16 static struct commit *check_commit(struct object *obj,
  17                                    const unsigned char *sha1,
  18                                    int quiet)
  19 {
  20         if (obj->type != OBJ_COMMIT) {
  21                 if (!quiet)
  22                         error("Object %s is a %s, not a commit",
  23                               sha1_to_hex(sha1), typename(obj->type));
  24                 return NULL;
  25         }
  26         return (struct commit *) obj;
  27 }
  28
  29 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  30                                               int quiet)
  31 {
  32         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  33
  34         if (!obj)
  35                 return NULL;
  36         return check_commit(obj, sha1, quiet);
  37 }
  38
  39 struct commit *lookup_commit_reference(const unsigned char *sha1)
  40 {
  41         return lookup_commit_reference_gently(sha1, 0);
  42 }
  43
  44 struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  45 {
  46         struct commit *c = lookup_commit_reference(sha1);
  47         if (!c)
  48                 die(_("could not parse %s"), ref_name);
  49         if (hashcmp(sha1, c->object.sha1)) {
  50                 warning(_("%s %s is not a commit!"),
  51                         ref_name, sha1_to_hex(sha1));
  52         }
  53         return c;
  54 }
  55
  56 struct commit *lookup_commit(const unsigned char *sha1)
  57 {
  58         struct object *obj = lookup_object(sha1);
  59         if (!obj)
  60                 return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  61         if (!obj->type)
  62                 obj->type = OBJ_COMMIT;
  63         return check_commit(obj, sha1, 0);
  64 }
  65
  66 struct commit *lookup_commit_reference_by_name(const char *name)
  67 {
  68         unsigned char sha1[20];
  69         struct commit *commit;
  70
  71         if (get_sha1(name, sha1))
  72                 return NULL;
  73         commit = lookup_commit_reference(sha1);
  74         if (!commit || parse_commit(commit))
  75                 return NULL;
  76         return commit;
  77 }
  78
  79 static unsigned long parse_commit_date(const char *buf, const char *tail)
  80 {
  81         const char *dateptr;
  82
  83         if (buf + 6 >= tail)
  84                 return 0;
  85         if (memcmp(buf, "author", 6))
  86                 return 0;
  87         while (buf < tail && *buf++ != '\n')
  88                 /* nada */;
  89         if (buf + 9 >= tail)
  90                 return 0;
  91         if (memcmp(buf, "committer", 9))
  92                 return 0;
  93         while (buf < tail && *buf++ != '>')
  94                 /* nada */;
  95         if (buf >= tail)
  96                 return 0;
  97         dateptr = buf;
  98         while (buf < tail && *buf++ != '\n')
  99                 /* nada */;
 100         if (buf >= tail)
 101                 return 0;
 102         /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 103         return strtoul(dateptr, NULL, 10);
 104 }
 105
 106 static struct commit_graft **commit_graft;
 107 static int commit_graft_alloc, commit_graft_nr;
 108
 109 static int commit_graft_pos(const unsigned char *sha1)
 110 {
 111         int lo, hi;
 112         lo = 0;
 113         hi = commit_graft_nr;
 114         while (lo < hi) {
 115                 int mi = (lo + hi) / 2;
 116                 struct commit_graft *graft = commit_graft[mi];
 117                 int cmp = hashcmp(sha1, graft->sha1);
 118                 if (!cmp)
 119                         return mi;
 120                 if (cmp < 0)
 121                         hi = mi;
 122                 else
 123                         lo = mi + 1;
 124         }
 125         return -lo - 1;
 126 }
 127
 128 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 129 {
 130         int pos = commit_graft_pos(graft->sha1);
 131
 132         if (0 <= pos) {
 133                 if (ignore_dups)
 134                         free(graft);
 135                 else {
 136                         free(commit_graft[pos]);
 137                         commit_graft[pos] = graft;
 138                 }
 139                 return 1;
 140         }
 141         pos = -pos - 1;
 142         if (commit_graft_alloc <= ++commit_graft_nr) {
 143                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 144                 commit_graft = xrealloc(commit_graft,
 145                                         sizeof(*commit_graft) *
 146                                         commit_graft_alloc);
 147         }
 148         if (pos < commit_graft_nr)
 149                 memmove(commit_graft + pos + 1,
 150                         commit_graft + pos,
 151                         (commit_graft_nr - pos - 1) *
 152                         sizeof(*commit_graft));
 153         commit_graft[pos] = graft;
 154         return 0;
 155 }
 156
 157 struct commit_graft *read_graft_line(char *buf, int len)
 158 {
 159         /* The format is just "Commit Parent1 Parent2 ...\n" */
 160         int i;
 161         struct commit_graft *graft = NULL;
 162
 163         while (len && isspace(buf[len-1]))
 164                 buf[--len] = '\0';
 165         if (buf[0] == '#' || buf[0] == '\0')
 166                 return NULL;
 167         if ((len + 1) % 41)
 168                 goto bad_graft_data;
 169         i = (len + 1) / 41 - 1;
 170         graft = xmalloc(sizeof(*graft) + 20 * i);
 171         graft->nr_parent = i;
 172         if (get_sha1_hex(buf, graft->sha1))
 173                 goto bad_graft_data;
 174         for (i = 40; i < len; i += 41) {
 175                 if (buf[i] != ' ')
 176                         goto bad_graft_data;
 177                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 178                         goto bad_graft_data;
 179         }
 180         return graft;
 181
 182 bad_graft_data:
 183         error("bad graft data: %s", buf);
 184         free(graft);
 185         return NULL;
 186 }
 187
 188 static int read_graft_file(const char *graft_file)
 189 {
 190         FILE *fp = fopen(graft_file, "r");
 191         char buf[1024];
 192         if (!fp)
 193                 return -1;
 194         while (fgets(buf, sizeof(buf), fp)) {
 195                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 196                 int len = strlen(buf);
 197                 struct commit_graft *graft = read_graft_line(buf, len);
 198                 if (!graft)
 199                         continue;
 200                 if (register_commit_graft(graft, 1))
 201                         error("duplicate graft data: %s", buf);
 202         }
 203         fclose(fp);
 204         return 0;
 205 }
 206
 207 static void prepare_commit_graft(void)
 208 {
 209         static int commit_graft_prepared;
 210         char *graft_file;
 211
 212         if (commit_graft_prepared)
 213                 return;
 214         graft_file = get_graft_file();
 215         read_graft_file(graft_file);
 216         /* make sure shallows are read */
 217         is_repository_shallow();
 218         commit_graft_prepared = 1;
 219 }
 220
 221 struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 222 {
 223         int pos;
 224         prepare_commit_graft();
 225         pos = commit_graft_pos(sha1);
 226         if (pos < 0)
 227                 return NULL;
 228         return commit_graft[pos];
 229 }
 230
 231 int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 232 {
 233         int i, ret;
 234         for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 235                 ret = fn(commit_graft[i], cb_data);
 236         return ret;
 237 }
 238
 239 int unregister_shallow(const unsigned char *sha1)
 240 {
 241         int pos = commit_graft_pos(sha1);
 242         if (pos < 0)
 243                 return -1;
 244         if (pos + 1 < commit_graft_nr)
 245                 memmove(commit_graft + pos, commit_graft + pos + 1,
 246                                 sizeof(struct commit_graft *)
 247                                 * (commit_graft_nr - pos - 1));
 248         commit_graft_nr--;
 249         return 0;
 250 }
 251
 252 int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 253 {
 254         const char *tail = buffer;
 255         const char *bufptr = buffer;
 256         unsigned char parent[20];
 257         struct commit_list **pptr;
 258         struct commit_graft *graft;
 259
 260         if (item->object.parsed)
 261                 return 0;
 262         item->object.parsed = 1;
 263         tail += size;
 264         if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 265                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 266         if (get_sha1_hex(bufptr + 5, parent) < 0)
 267                 return error("bad tree pointer in commit %s",
 268                              sha1_to_hex(item->object.sha1));
 269         item->tree = lookup_tree(parent);
 270         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 271         pptr = &item->parents;
 272
 273         graft = lookup_commit_graft(item->object.sha1);
 274         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 275                 struct commit *new_parent;
 276
 277                 if (tail <= bufptr + 48 ||
 278                     get_sha1_hex(bufptr + 7, parent) ||
 279                     bufptr[47] != '\n')
 280                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 281                 bufptr += 48;
 282                 /*
 283                  * The clone is shallow if nr_parent < 0, and we must
 284                  * not traverse its real parents even when we unhide them.
 285                  */
 286                 if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 287                         continue;
 288                 new_parent = lookup_commit(parent);
 289                 if (new_parent)
 290                         pptr = &commit_list_insert(new_parent, pptr)->next;
 291         }
 292         if (graft) {
 293                 int i;
 294                 struct commit *new_parent;
 295                 for (i = 0; i < graft->nr_parent; i++) {
 296                         new_parent = lookup_commit(graft->parent[i]);
 297                         if (!new_parent)
 298                                 continue;
 299                         pptr = &commit_list_insert(new_parent, pptr)->next;
 300                 }
 301         }
 302         item->date = parse_commit_date(bufptr, tail);
 303
 304         return 0;
 305 }
 306
 307 int parse_commit(struct commit *item)
 308 {
 309         enum object_type type;
 310         void *buffer;
 311         unsigned long size;
 312         int ret;
 313
 314         if (!item)
 315                 return -1;
 316         if (item->object.parsed)
 317                 return 0;
 318         buffer = read_sha1_file(item->object.sha1, &type, &size);
 319         if (!buffer)
 320                 return error("Could not read %s",
 321                              sha1_to_hex(item->object.sha1));
 322         if (type != OBJ_COMMIT) {
 323                 free(buffer);
 324                 return error("Object %s not a commit",
 325                              sha1_to_hex(item->object.sha1));
 326         }
 327         ret = parse_commit_buffer(item, buffer, size);
 328         if (save_commit_buffer && !ret) {
 329                 item->buffer = buffer;
 330                 return 0;
 331         }
 332         free(buffer);
 333         return ret;
 334 }
 335
 336 int find_commit_subject(const char *commit_buffer, const char **subject)
 337 {
 338         const char *eol;
 339         const char *p = commit_buffer;
 340
 341         while (*p && (*p != '\n' || p[1] != '\n'))
 342                 p++;
 343         if (*p) {
 344                 p += 2;
 345                 for (eol = p; *eol && *eol != '\n'; eol++)
 346                         ; /* do nothing */
 347         } else
 348                 eol = p;
 349
 350         *subject = p;
 351
 352         return eol - p;
 353 }
 354
 355 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 356 {
 357         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 358         new_list->item = item;
 359         new_list->next = *list_p;
 360         *list_p = new_list;
 361         return new_list;
 362 }
 363
 364 unsigned commit_list_count(const struct commit_list *l)
 365 {
 366         unsigned c = 0;
 367         for (; l; l = l->next )
 368                 c++;
 369         return c;
 370 }
 371
 372 void free_commit_list(struct commit_list *list)
 373 {
 374         while (list) {
 375                 struct commit_list *temp = list;
 376                 list = temp->next;
 377                 free(temp);
 378         }
 379 }
 380
 381 struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 382 {
 383         struct commit_list **pp = list;
 384         struct commit_list *p;
 385         while ((p = *pp) != NULL) {
 386                 if (p->item->date < item->date) {
 387                         break;
 388                 }
 389                 pp = &p->next;
 390         }
 391         return commit_list_insert(item, pp);
 392 }
 393
 394 static int commit_list_compare_by_date(const void *a, const void *b)
 395 {
 396         unsigned long a_date = ((const struct commit_list *)a)->item->date;
 397         unsigned long b_date = ((const struct commit_list *)b)->item->date;
 398         if (a_date < b_date)
 399                 return 1;
 400         if (a_date > b_date)
 401                 return -1;
 402         return 0;
 403 }
 404
 405 static void *commit_list_get_next(const void *a)
 406 {
 407         return ((const struct commit_list *)a)->next;
 408 }
 409
 410 static void commit_list_set_next(void *a, void *next)
 411 {
 412         ((struct commit_list *)a)->next = next;
 413 }
 414
 415 void commit_list_sort_by_date(struct commit_list **list)
 416 {
 417         *list = mergesort(*list, commit_list_get_next, commit_list_set_next,
 418                           commit_list_compare_by_date);
 419 }
 420
 421 struct commit *pop_most_recent_commit(struct commit_list **list,
 422                                       unsigned int mark)
 423 {
 424         struct commit *ret = (*list)->item;
 425         struct commit_list *parents = ret->parents;
 426         struct commit_list *old = *list;
 427
 428         *list = (*list)->next;
 429         free(old);
 430
 431         while (parents) {
 432                 struct commit *commit = parents->item;
 433                 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 434                         commit->object.flags |= mark;
 435                         commit_list_insert_by_date(commit, list);
 436                 }
 437                 parents = parents->next;
 438         }
 439         return ret;
 440 }
 441
 442 void clear_commit_marks(struct commit *commit, unsigned int mark)
 443 {
 444         while (commit) {
 445                 struct commit_list *parents;
 446
 447                 if (!(mark & commit->object.flags))
 448                         return;
 449
 450                 commit->object.flags &= ~mark;
 451
 452                 parents = commit->parents;
 453                 if (!parents)
 454                         return;
 455
 456                 while ((parents = parents->next))
 457                         clear_commit_marks(parents->item, mark);
 458
 459                 commit = commit->parents->item;
 460         }
 461 }
 462
 463 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 464 {
 465         struct object *object;
 466         struct commit *commit;
 467         unsigned int i;
 468
 469         for (i = 0; i < a->nr; i++) {
 470                 object = a->objects[i].item;
 471                 commit = lookup_commit_reference_gently(object->sha1, 1);
 472                 if (commit)
 473                         clear_commit_marks(commit, mark);
 474         }
 475 }
 476
 477 struct commit *pop_commit(struct commit_list **stack)
 478 {
 479         struct commit_list *top = *stack;
 480         struct commit *item = top ? top->item : NULL;
 481
 482         if (top) {
 483                 *stack = top->next;
 484                 free(top);
 485         }
 486         return item;
 487 }
 488
 489 /*
 490  * Performs an in-place topological sort on the list supplied.
 491  */
 492 void sort_in_topological_order(struct commit_list ** list, int lifo)
 493 {
 494         struct commit_list *next, *orig = *list;
 495         struct commit_list *work, **insert;
 496         struct commit_list **pptr;
 497
 498         if (!orig)
 499                 return;
 500         *list = NULL;
 501
 502         /* Mark them and clear the indegree */
 503         for (next = orig; next; next = next->next) {
 504                 struct commit *commit = next->item;
 505                 commit->indegree = 1;
 506         }
 507
 508         /* update the indegree */
 509         for (next = orig; next; next = next->next) {
 510                 struct commit_list * parents = next->item->parents;
 511                 while (parents) {
 512                         struct commit *parent = parents->item;
 513
 514                         if (parent->indegree)
 515                                 parent->indegree++;
 516                         parents = parents->next;
 517                 }
 518         }
 519
 520         /*
 521          * find the tips
 522          *
 523          * tips are nodes not reachable from any other node in the list
 524          *
 525          * the tips serve as a starting set for the work queue.
 526          */
 527         work = NULL;
 528         insert = &work;
 529         for (next = orig; next; next = next->next) {
 530                 struct commit *commit = next->item;
 531
 532                 if (commit->indegree == 1)
 533                         insert = &commit_list_insert(commit, insert)->next;
 534         }
 535
 536         /* process the list in topological order */
 537         if (!lifo)
 538                 commit_list_sort_by_date(&work);
 539
 540         pptr = list;
 541         *list = NULL;
 542         while (work) {
 543                 struct commit *commit;
 544                 struct commit_list *parents, *work_item;
 545
 546                 work_item = work;
 547                 work = work_item->next;
 548                 work_item->next = NULL;
 549
 550                 commit = work_item->item;
 551                 for (parents = commit->parents; parents ; parents = parents->next) {
 552                         struct commit *parent = parents->item;
 553
 554                         if (!parent->indegree)
 555                                 continue;
 556
 557                         /*
 558                          * parents are only enqueued for emission
 559                          * when all their children have been emitted thereby
 560                          * guaranteeing topological order.
 561                          */
 562                         if (--parent->indegree == 1) {
 563                                 if (!lifo)
 564                                         commit_list_insert_by_date(parent, &work);
 565                                 else
 566                                         commit_list_insert(parent, &work);
 567                         }
 568                 }
 569                 /*
 570                  * work_item is a commit all of whose children
 571                  * have already been emitted. we can emit it now.
 572                  */
 573                 commit->indegree = 0;
 574                 *pptr = work_item;
 575                 pptr = &work_item->next;
 576         }
 577 }
 578
 579 /* merge-base stuff */
 580
 581 /* bits #0..15 in revision.h */
 582 #define PARENT1         (1u<<16)
 583 #define PARENT2         (1u<<17)
 584 #define STALE           (1u<<18)
 585 #define RESULT          (1u<<19)
 586
 587 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 588
 589 static struct commit *interesting(struct commit_list *list)
 590 {
 591         while (list) {
 592                 struct commit *commit = list->item;
 593                 list = list->next;
 594                 if (commit->object.flags & STALE)
 595                         continue;
 596                 return commit;
 597         }
 598         return NULL;
 599 }
 600
 601 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 602 {
 603         struct commit_list *list = NULL;
 604         struct commit_list *result = NULL;
 605         int i;
 606
 607         for (i = 0; i < n; i++) {
 608                 if (one == twos[i])
 609                         /*
 610                          * We do not mark this even with RESULT so we do not
 611                          * have to clean it up.
 612                          */
 613                         return commit_list_insert(one, &result);
 614         }
 615
 616         if (parse_commit(one))
 617                 return NULL;
 618         for (i = 0; i < n; i++) {
 619                 if (parse_commit(twos[i]))
 620                         return NULL;
 621         }
 622
 623         one->object.flags |= PARENT1;
 624         commit_list_insert_by_date(one, &list);
 625         for (i = 0; i < n; i++) {
 626                 twos[i]->object.flags |= PARENT2;
 627                 commit_list_insert_by_date(twos[i], &list);
 628         }
 629
 630         while (interesting(list)) {
 631                 struct commit *commit;
 632                 struct commit_list *parents;
 633                 struct commit_list *next;
 634                 int flags;
 635
 636                 commit = list->item;
 637                 next = list->next;
 638                 free(list);
 639                 list = next;
 640
 641                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 642                 if (flags == (PARENT1 | PARENT2)) {
 643                         if (!(commit->object.flags & RESULT)) {
 644                                 commit->object.flags |= RESULT;
 645                                 commit_list_insert_by_date(commit, &result);
 646                         }
 647                         /* Mark parents of a found merge stale */
 648                         flags |= STALE;
 649                 }
 650                 parents = commit->parents;
 651                 while (parents) {
 652                         struct commit *p = parents->item;
 653                         parents = parents->next;
 654                         if ((p->object.flags & flags) == flags)
 655                                 continue;
 656                         if (parse_commit(p))
 657                                 return NULL;
 658                         p->object.flags |= flags;
 659                         commit_list_insert_by_date(p, &list);
 660                 }
 661         }
 662
 663         /* Clean up the result to remove stale ones */
 664         free_commit_list(list);
 665         list = result; result = NULL;
 666         while (list) {
 667                 struct commit_list *next = list->next;
 668                 if (!(list->item->object.flags & STALE))
 669                         commit_list_insert_by_date(list->item, &result);
 670                 free(list);
 671                 list = next;
 672         }
 673         return result;
 674 }
 675
 676 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 677 {
 678         struct commit_list *i, *j, *k, *ret = NULL;
 679         struct commit_list **pptr = &ret;
 680
 681         for (i = in; i; i = i->next) {
 682                 if (!ret)
 683                         pptr = &commit_list_insert(i->item, pptr)->next;
 684                 else {
 685                         struct commit_list *new = NULL, *end = NULL;
 686
 687                         for (j = ret; j; j = j->next) {
 688                                 struct commit_list *bases;
 689                                 bases = get_merge_bases(i->item, j->item, 1);
 690                                 if (!new)
 691                                         new = bases;
 692                                 else
 693                                         end->next = bases;
 694                                 for (k = bases; k; k = k->next)
 695                                         end = k;
 696                         }
 697                         ret = new;
 698                 }
 699         }
 700         return ret;
 701 }
 702
 703 struct commit_list *get_merge_bases_many(struct commit *one,
 704                                          int n,
 705                                          struct commit **twos,
 706                                          int cleanup)
 707 {
 708         struct commit_list *list;
 709         struct commit **rslt;
 710         struct commit_list *result;
 711         int cnt, i, j;
 712
 713         result = merge_bases_many(one, n, twos);
 714         for (i = 0; i < n; i++) {
 715                 if (one == twos[i])
 716                         return result;
 717         }
 718         if (!result || !result->next) {
 719                 if (cleanup) {
 720                         clear_commit_marks(one, all_flags);
 721                         for (i = 0; i < n; i++)
 722                                 clear_commit_marks(twos[i], all_flags);
 723                 }
 724                 return result;
 725         }
 726
 727         /* There are more than one */
 728         cnt = 0;
 729         list = result;
 730         while (list) {
 731                 list = list->next;
 732                 cnt++;
 733         }
 734         rslt = xcalloc(cnt, sizeof(*rslt));
 735         for (list = result, i = 0; list; list = list->next)
 736                 rslt[i++] = list->item;
 737         free_commit_list(result);
 738
 739         clear_commit_marks(one, all_flags);
 740         for (i = 0; i < n; i++)
 741                 clear_commit_marks(twos[i], all_flags);
 742         for (i = 0; i < cnt - 1; i++) {
 743                 for (j = i+1; j < cnt; j++) {
 744                         if (!rslt[i] || !rslt[j])
 745                                 continue;
 746                         result = merge_bases_many(rslt[i], 1, &rslt[j]);
 747                         clear_commit_marks(rslt[i], all_flags);
 748                         clear_commit_marks(rslt[j], all_flags);
 749                         for (list = result; list; list = list->next) {
 750                                 if (rslt[i] == list->item)
 751                                         rslt[i] = NULL;
 752                                 if (rslt[j] == list->item)
 753                                         rslt[j] = NULL;
 754                         }
 755                 }
 756         }
 757
 758         /* Surviving ones in rslt[] are the independent results */
 759         result = NULL;
 760         for (i = 0; i < cnt; i++) {
 761                 if (rslt[i])
 762                         commit_list_insert_by_date(rslt[i], &result);
 763         }
 764         free(rslt);
 765         return result;
 766 }
 767
 768 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 769                                     int cleanup)
 770 {
 771         return get_merge_bases_many(one, 1, &two, cleanup);
 772 }
 773
 774 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 775 {
 776         if (!with_commit)
 777                 return 1;
 778         while (with_commit) {
 779                 struct commit *other;
 780
 781                 other = with_commit->item;
 782                 with_commit = with_commit->next;
 783                 if (in_merge_bases(other, &commit, 1))
 784                         return 1;
 785         }
 786         return 0;
 787 }
 788
 789 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 790 {
 791         struct commit_list *bases, *b;
 792         int ret = 0;
 793
 794         if (num == 1)
 795                 bases = get_merge_bases(commit, *reference, 1);
 796         else
 797                 die("not yet");
 798         for (b = bases; b; b = b->next) {
 799                 if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 800                         ret = 1;
 801                         break;
 802                 }
 803         }
 804
 805         free_commit_list(bases);
 806         return ret;
 807 }
 808
 809 struct commit_list *reduce_heads(struct commit_list *heads)
 810 {
 811         struct commit_list *p;
 812         struct commit_list *result = NULL, **tail = &result;
 813         struct commit **other;
 814         size_t num_head, num_other;
 815
 816         if (!heads)
 817                 return NULL;
 818
 819         /* Avoid unnecessary reallocations */
 820         for (p = heads, num_head = 0; p; p = p->next)
 821                 num_head++;
 822         other = xcalloc(sizeof(*other), num_head);
 823
 824         /* For each commit, see if it can be reached by others */
 825         for (p = heads; p; p = p->next) {
 826                 struct commit_list *q, *base;
 827
 828                 /* Do we already have this in the result? */
 829                 for (q = result; q; q = q->next)
 830                         if (p->item == q->item)
 831                                 break;
 832                 if (q)
 833                         continue;
 834
 835                 num_other = 0;
 836                 for (q = heads; q; q = q->next) {
 837                         if (p->item == q->item)
 838                                 continue;
 839                         other[num_other++] = q->item;
 840                 }
 841                 if (num_other)
 842                         base = get_merge_bases_many(p->item, num_other, other, 1);
 843                 else
 844                         base = NULL;
 845                 /*
 846                  * If p->item does not have anything common with other
 847                  * commits, there won't be any merge base.  If it is
 848                  * reachable from some of the others, p->item will be
 849                  * the merge base.  If its history is connected with
 850                  * others, but p->item is not reachable by others, we
 851                  * will get something other than p->item back.
 852                  */
 853                 if (!base || (base->item != p->item))
 854                         tail = &(commit_list_insert(p->item, tail)->next);
 855                 free_commit_list(base);
 856         }
 857         free(other);
 858         return result;
 859 }
 860
 861 static const char gpg_sig_header[] = "gpgsig";
 862 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 863
 864 static int do_sign_commit(struct strbuf *buf, const char *keyid)
 865 {
 866         struct strbuf sig = STRBUF_INIT;
 867         int inspos, copypos;
 868
 869         /* find the end of the header */
 870         inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
 871
 872         if (!keyid || !*keyid)
 873                 keyid = get_signing_key();
 874         if (sign_buffer(buf, &sig, keyid)) {
 875                 strbuf_release(&sig);
 876                 return -1;
 877         }
 878
 879         for (copypos = 0; sig.buf[copypos]; ) {
 880                 const char *bol = sig.buf + copypos;
 881                 const char *eol = strchrnul(bol, '\n');
 882                 int len = (eol - bol) + !!*eol;
 883
 884                 if (!copypos) {
 885                         strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
 886                         inspos += gpg_sig_header_len;
 887                 }
 888                 strbuf_insert(buf, inspos++, " ", 1);
 889                 strbuf_insert(buf, inspos, bol, len);
 890                 inspos += len;
 891                 copypos += len;
 892         }
 893         strbuf_release(&sig);
 894         return 0;
 895 }
 896
 897 int parse_signed_commit(const unsigned char *sha1,
 898                         struct strbuf *payload, struct strbuf *signature)
 899 {
 900         unsigned long size;
 901         enum object_type type;
 902         char *buffer = read_sha1_file(sha1, &type, &size);
 903         int in_signature, saw_signature = -1;
 904         char *line, *tail;
 905
 906         if (!buffer || type != OBJ_COMMIT)
 907                 goto cleanup;
 908
 909         line = buffer;
 910         tail = buffer + size;
 911         in_signature = 0;
 912         saw_signature = 0;
 913         while (line < tail) {
 914                 const char *sig = NULL;
 915                 char *next = memchr(line, '\n', tail - line);
 916
 917                 next = next ? next + 1 : tail;
 918                 if (in_signature && line[0] == ' ')
 919                         sig = line + 1;
 920                 else if (!prefixcmp(line, gpg_sig_header) &&
 921                          line[gpg_sig_header_len] == ' ')
 922                         sig = line + gpg_sig_header_len + 1;
 923                 if (sig) {
 924                         strbuf_add(signature, sig, next - sig);
 925                         saw_signature = 1;
 926                         in_signature = 1;
 927                 } else {
 928                         if (*line == '\n')
 929                                 /* dump the whole remainder of the buffer */
 930                                 next = tail;
 931                         strbuf_add(payload, line, next - line);
 932                         in_signature = 0;
 933                 }
 934                 line = next;
 935         }
 936  cleanup:
 937         free(buffer);
 938         return saw_signature;
 939 }
 940
 941 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 942 {
 943         struct merge_remote_desc *desc;
 944         struct commit_extra_header *mergetag;
 945         char *buf;
 946         unsigned long size, len;
 947         enum object_type type;
 948
 949         desc = merge_remote_util(parent);
 950         if (!desc || !desc->obj)
 951                 return;
 952         buf = read_sha1_file(desc->obj->sha1, &type, &size);
 953         if (!buf || type != OBJ_TAG)
 954                 goto free_return;
 955         len = parse_signature(buf, size);
 956         if (size == len)
 957                 goto free_return;
 958         /*
 959          * We could verify this signature and either omit the tag when
 960          * it does not validate, but the integrator may not have the
 961          * public key of the signer of the tag he is merging, while a
 962          * later auditor may have it while auditing, so let's not run
 963          * verify-signed-buffer here for now...
 964          *
 965          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 966          *      warn("warning: signed tag unverified.");
 967          */
 968         mergetag = xcalloc(1, sizeof(*mergetag));
 969         mergetag->key = xstrdup("mergetag");
 970         mergetag->value = buf;
 971         mergetag->len = size;
 972
 973         **tail = mergetag;
 974         *tail = &mergetag->next;
 975         return;
 976
 977 free_return:
 978         free(buf);
 979 }
 980
 981 void append_merge_tag_headers(struct commit_list *parents,
 982                               struct commit_extra_header ***tail)
 983 {
 984         while (parents) {
 985                 struct commit *parent = parents->item;
 986                 handle_signed_tag(parent, tail);
 987                 parents = parents->next;
 988         }
 989 }
 990
 991 static void add_extra_header(struct strbuf *buffer,
 992                              struct commit_extra_header *extra)
 993 {
 994         strbuf_addstr(buffer, extra->key);
 995         if (extra->len)
 996                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
 997         else
 998                 strbuf_addch(buffer, '\n');
 999 }
1000
1001 struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1002                                                       const char **exclude)
1003 {
1004         struct commit_extra_header *extra = NULL;
1005         unsigned long size;
1006         enum object_type type;
1007         char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1008         if (buffer && type == OBJ_COMMIT)
1009                 extra = read_commit_extra_header_lines(buffer, size, exclude);
1010         free(buffer);
1011         return extra;
1012 }
1013
1014 static inline int standard_header_field(const char *field, size_t len)
1015 {
1016         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1017                 (len == 6 && !memcmp(field, "parent ", 7)) ||
1018                 (len == 6 && !memcmp(field, "author ", 7)) ||
1019                 (len == 9 && !memcmp(field, "committer ", 10)) ||
1020                 (len == 8 && !memcmp(field, "encoding ", 9)));
1021 }
1022
1023 static int excluded_header_field(const char *field, size_t len, const char **exclude)
1024 {
1025         if (!exclude)
1026                 return 0;
1027
1028         while (*exclude) {
1029                 size_t xlen = strlen(*exclude);
1030                 if (len == xlen &&
1031                     !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1032                         return 1;
1033                 exclude++;
1034         }
1035         return 0;
1036 }
1037
1038 struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size,
1039                                                            const char **exclude)
1040 {
1041         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1042         const char *line, *next, *eof, *eob;
1043         struct strbuf buf = STRBUF_INIT;
1044
1045         for (line = buffer, eob = line + size;
1046              line < eob && *line != '\n';
1047              line = next) {
1048                 next = memchr(line, '\n', eob - line);
1049                 next = next ? next + 1 : eob;
1050                 if (*line == ' ') {
1051                         /* continuation */
1052                         if (it)
1053                                 strbuf_add(&buf, line + 1, next - (line + 1));
1054                         continue;
1055                 }
1056                 if (it)
1057                         it->value = strbuf_detach(&buf, &it->len);
1058                 strbuf_reset(&buf);
1059                 it = NULL;
1060
1061                 eof = strchr(line, ' ');
1062                 if (next <= eof)
1063                         eof = next;
1064
1065                 if (standard_header_field(line, eof - line) ||
1066                     excluded_header_field(line, eof - line, exclude))
1067                         continue;
1068
1069                 it = xcalloc(1, sizeof(*it));
1070                 it->key = xmemdupz(line, eof-line);
1071                 *tail = it;
1072                 tail = &it->next;
1073                 if (eof + 1 < next)
1074                         strbuf_add(&buf, eof + 1, next - (eof + 1));
1075         }
1076         if (it)
1077                 it->value = strbuf_detach(&buf, &it->len);
1078         return extra;
1079 }
1080
1081 void free_commit_extra_headers(struct commit_extra_header *extra)
1082 {
1083         while (extra) {
1084                 struct commit_extra_header *next = extra->next;
1085                 free(extra->key);
1086                 free(extra->value);
1087                 free(extra);
1088                 extra = next;
1089         }
1090 }
1091
1092 int commit_tree(const struct strbuf *msg, unsigned char *tree,
1093                 struct commit_list *parents, unsigned char *ret,
1094                 const char *author, const char *sign_commit)
1095 {
1096         struct commit_extra_header *extra = NULL, **tail = &extra;
1097         int result;
1098
1099         append_merge_tag_headers(parents, &tail);
1100         result = commit_tree_extended(msg, tree, parents, ret,
1101                                       author, sign_commit, extra);
1102         free_commit_extra_headers(extra);
1103         return result;
1104 }
1105
1106 static const char commit_utf8_warn[] =
1107 "Warning: commit message does not conform to UTF-8.\n"
1108 "You may want to amend it after fixing the message, or set the config\n"
1109 "variable i18n.commitencoding to the encoding your project uses.\n";
1110
1111 int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1112                          struct commit_list *parents, unsigned char *ret,
1113                          const char *author, const char *sign_commit,
1114                          struct commit_extra_header *extra)
1115 {
1116         int result;
1117         int encoding_is_utf8;
1118         struct strbuf buffer;
1119
1120         assert_sha1_type(tree, OBJ_TREE);
1121
1122         if (memchr(msg->buf, '\0', msg->len))
1123                 return error("a NUL byte in commit log message not allowed.");
1124
1125         /* Not having i18n.commitencoding is the same as having utf-8 */
1126         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1127
1128         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1129         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1130
1131         /*
1132          * NOTE! This ordering means that the same exact tree merged with a
1133          * different order of parents will be a _different_ changeset even
1134          * if everything else stays the same.
1135          */
1136         while (parents) {
1137                 struct commit_list *next = parents->next;
1138                 struct commit *parent = parents->item;
1139
1140                 strbuf_addf(&buffer, "parent %s\n",
1141                             sha1_to_hex(parent->object.sha1));
1142                 free(parents);
1143                 parents = next;
1144         }
1145
1146         /* Person/date information */
1147         if (!author)
1148                 author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1149         strbuf_addf(&buffer, "author %s\n", author);
1150         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1151         if (!encoding_is_utf8)
1152                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1153
1154         while (extra) {
1155                 add_extra_header(&buffer, extra);
1156                 extra = extra->next;
1157         }
1158         strbuf_addch(&buffer, '\n');
1159
1160         /* And add the comment */
1161         strbuf_addbuf(&buffer, msg);
1162
1163         /* And check the encoding */
1164         if (encoding_is_utf8 && !is_utf8(buffer.buf))
1165                 fprintf(stderr, commit_utf8_warn);
1166
1167         if (sign_commit && do_sign_commit(&buffer, sign_commit))
1168                 return -1;
1169
1170         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1171         strbuf_release(&buffer);
1172         return result;
1173 }
1174
1175 struct commit *get_merge_parent(const char *name)
1176 {
1177         struct object *obj;
1178         struct commit *commit;
1179         unsigned char sha1[20];
1180         if (get_sha1(name, sha1))
1181                 return NULL;
1182         obj = parse_object(sha1);
1183         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1184         if (commit && !commit->util) {
1185                 struct merge_remote_desc *desc;
1186                 desc = xmalloc(sizeof(*desc));
1187                 desc->obj = obj;
1188                 desc->name = strdup(name);
1189                 commit->util = desc;
1190         }
1191         return commit;
1192 }