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 = llist_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 static void clear_commit_marks_1(struct commit_list **plist,
 443                                  struct commit *commit, unsigned int mark)
 444 {
 445         while (commit) {
 446                 struct commit_list *parents;
 447
 448                 if (!(mark & commit->object.flags))
 449                         return;
 450
 451                 commit->object.flags &= ~mark;
 452
 453                 parents = commit->parents;
 454                 if (!parents)
 455                         return;
 456
 457                 while ((parents = parents->next))
 458                         commit_list_insert(parents->item, plist);
 459
 460                 commit = commit->parents->item;
 461         }
 462 }
 463
 464 void clear_commit_marks(struct commit *commit, unsigned int mark)
 465 {
 466         struct commit_list *list = NULL;
 467         commit_list_insert(commit, &list);
 468         while (list)
 469                 clear_commit_marks_1(&list, pop_commit(&list), mark);
 470 }
 471
 472 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 473 {
 474         struct object *object;
 475         struct commit *commit;
 476         unsigned int i;
 477
 478         for (i = 0; i < a->nr; i++) {
 479                 object = a->objects[i].item;
 480                 commit = lookup_commit_reference_gently(object->sha1, 1);
 481                 if (commit)
 482                         clear_commit_marks(commit, mark);
 483         }
 484 }
 485
 486 struct commit *pop_commit(struct commit_list **stack)
 487 {
 488         struct commit_list *top = *stack;
 489         struct commit *item = top ? top->item : NULL;
 490
 491         if (top) {
 492                 *stack = top->next;
 493                 free(top);
 494         }
 495         return item;
 496 }
 497
 498 /*
 499  * Performs an in-place topological sort on the list supplied.
 500  */
 501 void sort_in_topological_order(struct commit_list ** list, int lifo)
 502 {
 503         struct commit_list *next, *orig = *list;
 504         struct commit_list *work, **insert;
 505         struct commit_list **pptr;
 506
 507         if (!orig)
 508                 return;
 509         *list = NULL;
 510
 511         /* Mark them and clear the indegree */
 512         for (next = orig; next; next = next->next) {
 513                 struct commit *commit = next->item;
 514                 commit->indegree = 1;
 515         }
 516
 517         /* update the indegree */
 518         for (next = orig; next; next = next->next) {
 519                 struct commit_list * parents = next->item->parents;
 520                 while (parents) {
 521                         struct commit *parent = parents->item;
 522
 523                         if (parent->indegree)
 524                                 parent->indegree++;
 525                         parents = parents->next;
 526                 }
 527         }
 528
 529         /*
 530          * find the tips
 531          *
 532          * tips are nodes not reachable from any other node in the list
 533          *
 534          * the tips serve as a starting set for the work queue.
 535          */
 536         work = NULL;
 537         insert = &work;
 538         for (next = orig; next; next = next->next) {
 539                 struct commit *commit = next->item;
 540
 541                 if (commit->indegree == 1)
 542                         insert = &commit_list_insert(commit, insert)->next;
 543         }
 544
 545         /* process the list in topological order */
 546         if (!lifo)
 547                 commit_list_sort_by_date(&work);
 548
 549         pptr = list;
 550         *list = NULL;
 551         while (work) {
 552                 struct commit *commit;
 553                 struct commit_list *parents, *work_item;
 554
 555                 work_item = work;
 556                 work = work_item->next;
 557                 work_item->next = NULL;
 558
 559                 commit = work_item->item;
 560                 for (parents = commit->parents; parents ; parents = parents->next) {
 561                         struct commit *parent = parents->item;
 562
 563                         if (!parent->indegree)
 564                                 continue;
 565
 566                         /*
 567                          * parents are only enqueued for emission
 568                          * when all their children have been emitted thereby
 569                          * guaranteeing topological order.
 570                          */
 571                         if (--parent->indegree == 1) {
 572                                 if (!lifo)
 573                                         commit_list_insert_by_date(parent, &work);
 574                                 else
 575                                         commit_list_insert(parent, &work);
 576                         }
 577                 }
 578                 /*
 579                  * work_item is a commit all of whose children
 580                  * have already been emitted. we can emit it now.
 581                  */
 582                 commit->indegree = 0;
 583                 *pptr = work_item;
 584                 pptr = &work_item->next;
 585         }
 586 }
 587
 588 /* merge-base stuff */
 589
 590 /* bits #0..15 in revision.h */
 591 #define PARENT1         (1u<<16)
 592 #define PARENT2         (1u<<17)
 593 #define STALE           (1u<<18)
 594 #define RESULT          (1u<<19)
 595
 596 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 597
 598 static struct commit *interesting(struct commit_list *list)
 599 {
 600         while (list) {
 601                 struct commit *commit = list->item;
 602                 list = list->next;
 603                 if (commit->object.flags & STALE)
 604                         continue;
 605                 return commit;
 606         }
 607         return NULL;
 608 }
 609
 610 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 611 {
 612         struct commit_list *list = NULL;
 613         struct commit_list *result = NULL;
 614         int i;
 615
 616         for (i = 0; i < n; i++) {
 617                 if (one == twos[i])
 618                         /*
 619                          * We do not mark this even with RESULT so we do not
 620                          * have to clean it up.
 621                          */
 622                         return commit_list_insert(one, &result);
 623         }
 624
 625         if (parse_commit(one))
 626                 return NULL;
 627         for (i = 0; i < n; i++) {
 628                 if (parse_commit(twos[i]))
 629                         return NULL;
 630         }
 631
 632         one->object.flags |= PARENT1;
 633         commit_list_insert_by_date(one, &list);
 634         for (i = 0; i < n; i++) {
 635                 twos[i]->object.flags |= PARENT2;
 636                 commit_list_insert_by_date(twos[i], &list);
 637         }
 638
 639         while (interesting(list)) {
 640                 struct commit *commit;
 641                 struct commit_list *parents;
 642                 struct commit_list *next;
 643                 int flags;
 644
 645                 commit = list->item;
 646                 next = list->next;
 647                 free(list);
 648                 list = next;
 649
 650                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 651                 if (flags == (PARENT1 | PARENT2)) {
 652                         if (!(commit->object.flags & RESULT)) {
 653                                 commit->object.flags |= RESULT;
 654                                 commit_list_insert_by_date(commit, &result);
 655                         }
 656                         /* Mark parents of a found merge stale */
 657                         flags |= STALE;
 658                 }
 659                 parents = commit->parents;
 660                 while (parents) {
 661                         struct commit *p = parents->item;
 662                         parents = parents->next;
 663                         if ((p->object.flags & flags) == flags)
 664                                 continue;
 665                         if (parse_commit(p))
 666                                 return NULL;
 667                         p->object.flags |= flags;
 668                         commit_list_insert_by_date(p, &list);
 669                 }
 670         }
 671
 672         /* Clean up the result to remove stale ones */
 673         free_commit_list(list);
 674         list = result; result = NULL;
 675         while (list) {
 676                 struct commit_list *next = list->next;
 677                 if (!(list->item->object.flags & STALE))
 678                         commit_list_insert_by_date(list->item, &result);
 679                 free(list);
 680                 list = next;
 681         }
 682         return result;
 683 }
 684
 685 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 686 {
 687         struct commit_list *i, *j, *k, *ret = NULL;
 688         struct commit_list **pptr = &ret;
 689
 690         for (i = in; i; i = i->next) {
 691                 if (!ret)
 692                         pptr = &commit_list_insert(i->item, pptr)->next;
 693                 else {
 694                         struct commit_list *new = NULL, *end = NULL;
 695
 696                         for (j = ret; j; j = j->next) {
 697                                 struct commit_list *bases;
 698                                 bases = get_merge_bases(i->item, j->item, 1);
 699                                 if (!new)
 700                                         new = bases;
 701                                 else
 702                                         end->next = bases;
 703                                 for (k = bases; k; k = k->next)
 704                                         end = k;
 705                         }
 706                         ret = new;
 707                 }
 708         }
 709         return ret;
 710 }
 711
 712 struct commit_list *get_merge_bases_many(struct commit *one,
 713                                          int n,
 714                                          struct commit **twos,
 715                                          int cleanup)
 716 {
 717         struct commit_list *list;
 718         struct commit **rslt;
 719         struct commit_list *result;
 720         int cnt, i, j;
 721
 722         result = merge_bases_many(one, n, twos);
 723         for (i = 0; i < n; i++) {
 724                 if (one == twos[i])
 725                         return result;
 726         }
 727         if (!result || !result->next) {
 728                 if (cleanup) {
 729                         clear_commit_marks(one, all_flags);
 730                         for (i = 0; i < n; i++)
 731                                 clear_commit_marks(twos[i], all_flags);
 732                 }
 733                 return result;
 734         }
 735
 736         /* There are more than one */
 737         cnt = 0;
 738         list = result;
 739         while (list) {
 740                 list = list->next;
 741                 cnt++;
 742         }
 743         rslt = xcalloc(cnt, sizeof(*rslt));
 744         for (list = result, i = 0; list; list = list->next)
 745                 rslt[i++] = list->item;
 746         free_commit_list(result);
 747
 748         clear_commit_marks(one, all_flags);
 749         for (i = 0; i < n; i++)
 750                 clear_commit_marks(twos[i], all_flags);
 751         for (i = 0; i < cnt - 1; i++) {
 752                 for (j = i+1; j < cnt; j++) {
 753                         if (!rslt[i] || !rslt[j])
 754                                 continue;
 755                         result = merge_bases_many(rslt[i], 1, &rslt[j]);
 756                         clear_commit_marks(rslt[i], all_flags);
 757                         clear_commit_marks(rslt[j], all_flags);
 758                         for (list = result; list; list = list->next) {
 759                                 if (rslt[i] == list->item)
 760                                         rslt[i] = NULL;
 761                                 if (rslt[j] == list->item)
 762                                         rslt[j] = NULL;
 763                         }
 764                 }
 765         }
 766
 767         /* Surviving ones in rslt[] are the independent results */
 768         result = NULL;
 769         for (i = 0; i < cnt; i++) {
 770                 if (rslt[i])
 771                         commit_list_insert_by_date(rslt[i], &result);
 772         }
 773         free(rslt);
 774         return result;
 775 }
 776
 777 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 778                                     int cleanup)
 779 {
 780         return get_merge_bases_many(one, 1, &two, cleanup);
 781 }
 782
 783 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 784 {
 785         if (!with_commit)
 786                 return 1;
 787         while (with_commit) {
 788                 struct commit *other;
 789
 790                 other = with_commit->item;
 791                 with_commit = with_commit->next;
 792                 if (in_merge_bases(other, &commit, 1))
 793                         return 1;
 794         }
 795         return 0;
 796 }
 797
 798 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 799 {
 800         struct commit_list *bases, *b;
 801         int ret = 0;
 802
 803         if (num == 1)
 804                 bases = get_merge_bases(commit, *reference, 1);
 805         else
 806                 die("not yet");
 807         for (b = bases; b; b = b->next) {
 808                 if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 809                         ret = 1;
 810                         break;
 811                 }
 812         }
 813
 814         free_commit_list(bases);
 815         return ret;
 816 }
 817
 818 struct commit_list *reduce_heads(struct commit_list *heads)
 819 {
 820         struct commit_list *p;
 821         struct commit_list *result = NULL, **tail = &result;
 822         struct commit **other;
 823         size_t num_head, num_other;
 824
 825         if (!heads)
 826                 return NULL;
 827
 828         /* Avoid unnecessary reallocations */
 829         for (p = heads, num_head = 0; p; p = p->next)
 830                 num_head++;
 831         other = xcalloc(sizeof(*other), num_head);
 832
 833         /* For each commit, see if it can be reached by others */
 834         for (p = heads; p; p = p->next) {
 835                 struct commit_list *q, *base;
 836
 837                 /* Do we already have this in the result? */
 838                 for (q = result; q; q = q->next)
 839                         if (p->item == q->item)
 840                                 break;
 841                 if (q)
 842                         continue;
 843
 844                 num_other = 0;
 845                 for (q = heads; q; q = q->next) {
 846                         if (p->item == q->item)
 847                                 continue;
 848                         other[num_other++] = q->item;
 849                 }
 850                 if (num_other)
 851                         base = get_merge_bases_many(p->item, num_other, other, 1);
 852                 else
 853                         base = NULL;
 854                 /*
 855                  * If p->item does not have anything common with other
 856                  * commits, there won't be any merge base.  If it is
 857                  * reachable from some of the others, p->item will be
 858                  * the merge base.  If its history is connected with
 859                  * others, but p->item is not reachable by others, we
 860                  * will get something other than p->item back.
 861                  */
 862                 if (!base || (base->item != p->item))
 863                         tail = &(commit_list_insert(p->item, tail)->next);
 864                 free_commit_list(base);
 865         }
 866         free(other);
 867         return result;
 868 }
 869
 870 static const char gpg_sig_header[] = "gpgsig";
 871 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 872
 873 static int do_sign_commit(struct strbuf *buf, const char *keyid)
 874 {
 875         struct strbuf sig = STRBUF_INIT;
 876         int inspos, copypos;
 877
 878         /* find the end of the header */
 879         inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
 880
 881         if (!keyid || !*keyid)
 882                 keyid = get_signing_key();
 883         if (sign_buffer(buf, &sig, keyid)) {
 884                 strbuf_release(&sig);
 885                 return -1;
 886         }
 887
 888         for (copypos = 0; sig.buf[copypos]; ) {
 889                 const char *bol = sig.buf + copypos;
 890                 const char *eol = strchrnul(bol, '\n');
 891                 int len = (eol - bol) + !!*eol;
 892
 893                 if (!copypos) {
 894                         strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
 895                         inspos += gpg_sig_header_len;
 896                 }
 897                 strbuf_insert(buf, inspos++, " ", 1);
 898                 strbuf_insert(buf, inspos, bol, len);
 899                 inspos += len;
 900                 copypos += len;
 901         }
 902         strbuf_release(&sig);
 903         return 0;
 904 }
 905
 906 int parse_signed_commit(const unsigned char *sha1,
 907                         struct strbuf *payload, struct strbuf *signature)
 908 {
 909         unsigned long size;
 910         enum object_type type;
 911         char *buffer = read_sha1_file(sha1, &type, &size);
 912         int in_signature, saw_signature = -1;
 913         char *line, *tail;
 914
 915         if (!buffer || type != OBJ_COMMIT)
 916                 goto cleanup;
 917
 918         line = buffer;
 919         tail = buffer + size;
 920         in_signature = 0;
 921         saw_signature = 0;
 922         while (line < tail) {
 923                 const char *sig = NULL;
 924                 char *next = memchr(line, '\n', tail - line);
 925
 926                 next = next ? next + 1 : tail;
 927                 if (in_signature && line[0] == ' ')
 928                         sig = line + 1;
 929                 else if (!prefixcmp(line, gpg_sig_header) &&
 930                          line[gpg_sig_header_len] == ' ')
 931                         sig = line + gpg_sig_header_len + 1;
 932                 if (sig) {
 933                         strbuf_add(signature, sig, next - sig);
 934                         saw_signature = 1;
 935                         in_signature = 1;
 936                 } else {
 937                         if (*line == '\n')
 938                                 /* dump the whole remainder of the buffer */
 939                                 next = tail;
 940                         strbuf_add(payload, line, next - line);
 941                         in_signature = 0;
 942                 }
 943                 line = next;
 944         }
 945  cleanup:
 946         free(buffer);
 947         return saw_signature;
 948 }
 949
 950 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 951 {
 952         struct merge_remote_desc *desc;
 953         struct commit_extra_header *mergetag;
 954         char *buf;
 955         unsigned long size, len;
 956         enum object_type type;
 957
 958         desc = merge_remote_util(parent);
 959         if (!desc || !desc->obj)
 960                 return;
 961         buf = read_sha1_file(desc->obj->sha1, &type, &size);
 962         if (!buf || type != OBJ_TAG)
 963                 goto free_return;
 964         len = parse_signature(buf, size);
 965         if (size == len)
 966                 goto free_return;
 967         /*
 968          * We could verify this signature and either omit the tag when
 969          * it does not validate, but the integrator may not have the
 970          * public key of the signer of the tag he is merging, while a
 971          * later auditor may have it while auditing, so let's not run
 972          * verify-signed-buffer here for now...
 973          *
 974          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 975          *      warn("warning: signed tag unverified.");
 976          */
 977         mergetag = xcalloc(1, sizeof(*mergetag));
 978         mergetag->key = xstrdup("mergetag");
 979         mergetag->value = buf;
 980         mergetag->len = size;
 981
 982         **tail = mergetag;
 983         *tail = &mergetag->next;
 984         return;
 985
 986 free_return:
 987         free(buf);
 988 }
 989
 990 void append_merge_tag_headers(struct commit_list *parents,
 991                               struct commit_extra_header ***tail)
 992 {
 993         while (parents) {
 994                 struct commit *parent = parents->item;
 995                 handle_signed_tag(parent, tail);
 996                 parents = parents->next;
 997         }
 998 }
 999
1000 static void add_extra_header(struct strbuf *buffer,
1001                              struct commit_extra_header *extra)
1002 {
1003         strbuf_addstr(buffer, extra->key);
1004         if (extra->len)
1005                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
1006         else
1007                 strbuf_addch(buffer, '\n');
1008 }
1009
1010 struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1011                                                       const char **exclude)
1012 {
1013         struct commit_extra_header *extra = NULL;
1014         unsigned long size;
1015         enum object_type type;
1016         char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1017         if (buffer && type == OBJ_COMMIT)
1018                 extra = read_commit_extra_header_lines(buffer, size, exclude);
1019         free(buffer);
1020         return extra;
1021 }
1022
1023 static inline int standard_header_field(const char *field, size_t len)
1024 {
1025         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1026                 (len == 6 && !memcmp(field, "parent ", 7)) ||
1027                 (len == 6 && !memcmp(field, "author ", 7)) ||
1028                 (len == 9 && !memcmp(field, "committer ", 10)) ||
1029                 (len == 8 && !memcmp(field, "encoding ", 9)));
1030 }
1031
1032 static int excluded_header_field(const char *field, size_t len, const char **exclude)
1033 {
1034         if (!exclude)
1035                 return 0;
1036
1037         while (*exclude) {
1038                 size_t xlen = strlen(*exclude);
1039                 if (len == xlen &&
1040                     !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1041                         return 1;
1042                 exclude++;
1043         }
1044         return 0;
1045 }
1046
1047 struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size,
1048                                                            const char **exclude)
1049 {
1050         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1051         const char *line, *next, *eof, *eob;
1052         struct strbuf buf = STRBUF_INIT;
1053
1054         for (line = buffer, eob = line + size;
1055              line < eob && *line != '\n';
1056              line = next) {
1057                 next = memchr(line, '\n', eob - line);
1058                 next = next ? next + 1 : eob;
1059                 if (*line == ' ') {
1060                         /* continuation */
1061                         if (it)
1062                                 strbuf_add(&buf, line + 1, next - (line + 1));
1063                         continue;
1064                 }
1065                 if (it)
1066                         it->value = strbuf_detach(&buf, &it->len);
1067                 strbuf_reset(&buf);
1068                 it = NULL;
1069
1070                 eof = strchr(line, ' ');
1071                 if (next <= eof)
1072                         eof = next;
1073
1074                 if (standard_header_field(line, eof - line) ||
1075                     excluded_header_field(line, eof - line, exclude))
1076                         continue;
1077
1078                 it = xcalloc(1, sizeof(*it));
1079                 it->key = xmemdupz(line, eof-line);
1080                 *tail = it;
1081                 tail = &it->next;
1082                 if (eof + 1 < next)
1083                         strbuf_add(&buf, eof + 1, next - (eof + 1));
1084         }
1085         if (it)
1086                 it->value = strbuf_detach(&buf, &it->len);
1087         return extra;
1088 }
1089
1090 void free_commit_extra_headers(struct commit_extra_header *extra)
1091 {
1092         while (extra) {
1093                 struct commit_extra_header *next = extra->next;
1094                 free(extra->key);
1095                 free(extra->value);
1096                 free(extra);
1097                 extra = next;
1098         }
1099 }
1100
1101 int commit_tree(const struct strbuf *msg, unsigned char *tree,
1102                 struct commit_list *parents, unsigned char *ret,
1103                 const char *author, const char *sign_commit)
1104 {
1105         struct commit_extra_header *extra = NULL, **tail = &extra;
1106         int result;
1107
1108         append_merge_tag_headers(parents, &tail);
1109         result = commit_tree_extended(msg, tree, parents, ret,
1110                                       author, sign_commit, extra);
1111         free_commit_extra_headers(extra);
1112         return result;
1113 }
1114
1115 static const char commit_utf8_warn[] =
1116 "Warning: commit message does not conform to UTF-8.\n"
1117 "You may want to amend it after fixing the message, or set the config\n"
1118 "variable i18n.commitencoding to the encoding your project uses.\n";
1119
1120 int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1121                          struct commit_list *parents, unsigned char *ret,
1122                          const char *author, const char *sign_commit,
1123                          struct commit_extra_header *extra)
1124 {
1125         int result;
1126         int encoding_is_utf8;
1127         struct strbuf buffer;
1128
1129         assert_sha1_type(tree, OBJ_TREE);
1130
1131         if (memchr(msg->buf, '\0', msg->len))
1132                 return error("a NUL byte in commit log message not allowed.");
1133
1134         /* Not having i18n.commitencoding is the same as having utf-8 */
1135         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1136
1137         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1138         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1139
1140         /*
1141          * NOTE! This ordering means that the same exact tree merged with a
1142          * different order of parents will be a _different_ changeset even
1143          * if everything else stays the same.
1144          */
1145         while (parents) {
1146                 struct commit_list *next = parents->next;
1147                 struct commit *parent = parents->item;
1148
1149                 strbuf_addf(&buffer, "parent %s\n",
1150                             sha1_to_hex(parent->object.sha1));
1151                 free(parents);
1152                 parents = next;
1153         }
1154
1155         /* Person/date information */
1156         if (!author)
1157                 author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1158         strbuf_addf(&buffer, "author %s\n", author);
1159         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1160         if (!encoding_is_utf8)
1161                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1162
1163         while (extra) {
1164                 add_extra_header(&buffer, extra);
1165                 extra = extra->next;
1166         }
1167         strbuf_addch(&buffer, '\n');
1168
1169         /* And add the comment */
1170         strbuf_addbuf(&buffer, msg);
1171
1172         /* And check the encoding */
1173         if (encoding_is_utf8 && !is_utf8(buffer.buf))
1174                 fprintf(stderr, commit_utf8_warn);
1175
1176         if (sign_commit && do_sign_commit(&buffer, sign_commit))
1177                 return -1;
1178
1179         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1180         strbuf_release(&buffer);
1181         return result;
1182 }
1183
1184 struct commit *get_merge_parent(const char *name)
1185 {
1186         struct object *obj;
1187         struct commit *commit;
1188         unsigned char sha1[20];
1189         if (get_sha1(name, sha1))
1190                 return NULL;
1191         obj = parse_object(sha1);
1192         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1193         if (commit && !commit->util) {
1194                 struct merge_remote_desc *desc;
1195                 desc = xmalloc(sizeof(*desc));
1196                 desc->obj = obj;
1197                 desc->name = strdup(name);
1198                 commit->util = desc;
1199         }
1200         return commit;
1201 }
1202
1203 /*
1204  * Append a commit to the end of the commit_list.
1205  *
1206  * next starts by pointing to the variable that holds the head of an
1207  * empty commit_list, and is updated to point to the "next" field of
1208  * the last item on the list as new commits are appended.
1209  *
1210  * Usage example:
1211  *
1212  *     struct commit_list *list;
1213  *     struct commit_list **next = &list;
1214  *
1215  *     next = commit_list_append(c1, next);
1216  *     next = commit_list_append(c2, next);
1217  *     assert(commit_list_count(list) == 2);
1218  *     return list;
1219  */
1220 struct commit_list **commit_list_append(struct commit *commit,
1221                                         struct commit_list **next)
1222 {
1223         struct commit_list *new = xmalloc(sizeof(struct commit_list));
1224         new->item = commit;
1225         *next = new;
1226         new->next = NULL;
1227         return &new->next;
1228 }