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 void commit_list_reverse(struct commit_list **list_p)
 365 {
 366         struct commit_list *prev = NULL, *curr = *list_p, *next;
 367
 368         if (!list_p)
 369                 return;
 370         while (curr) {
 371                 next = curr->next;
 372                 curr->next = prev;
 373                 prev = curr;
 374                 curr = next;
 375         }
 376         *list_p = prev;
 377 }
 378
 379 unsigned commit_list_count(const struct commit_list *l)
 380 {
 381         unsigned c = 0;
 382         for (; l; l = l->next )
 383                 c++;
 384         return c;
 385 }
 386
 387 void free_commit_list(struct commit_list *list)
 388 {
 389         while (list) {
 390                 struct commit_list *temp = list;
 391                 list = temp->next;
 392                 free(temp);
 393         }
 394 }
 395
 396 struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 397 {
 398         struct commit_list **pp = list;
 399         struct commit_list *p;
 400         while ((p = *pp) != NULL) {
 401                 if (p->item->date < item->date) {
 402                         break;
 403                 }
 404                 pp = &p->next;
 405         }
 406         return commit_list_insert(item, pp);
 407 }
 408
 409 static int commit_list_compare_by_date(const void *a, const void *b)
 410 {
 411         unsigned long a_date = ((const struct commit_list *)a)->item->date;
 412         unsigned long b_date = ((const struct commit_list *)b)->item->date;
 413         if (a_date < b_date)
 414                 return 1;
 415         if (a_date > b_date)
 416                 return -1;
 417         return 0;
 418 }
 419
 420 static void *commit_list_get_next(const void *a)
 421 {
 422         return ((const struct commit_list *)a)->next;
 423 }
 424
 425 static void commit_list_set_next(void *a, void *next)
 426 {
 427         ((struct commit_list *)a)->next = next;
 428 }
 429
 430 void commit_list_sort_by_date(struct commit_list **list)
 431 {
 432         *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 433                                 commit_list_compare_by_date);
 434 }
 435
 436 struct commit *pop_most_recent_commit(struct commit_list **list,
 437                                       unsigned int mark)
 438 {
 439         struct commit *ret = (*list)->item;
 440         struct commit_list *parents = ret->parents;
 441         struct commit_list *old = *list;
 442
 443         *list = (*list)->next;
 444         free(old);
 445
 446         while (parents) {
 447                 struct commit *commit = parents->item;
 448                 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 449                         commit->object.flags |= mark;
 450                         commit_list_insert_by_date(commit, list);
 451                 }
 452                 parents = parents->next;
 453         }
 454         return ret;
 455 }
 456
 457 static void clear_commit_marks_1(struct commit_list **plist,
 458                                  struct commit *commit, unsigned int mark)
 459 {
 460         while (commit) {
 461                 struct commit_list *parents;
 462
 463                 if (!(mark & commit->object.flags))
 464                         return;
 465
 466                 commit->object.flags &= ~mark;
 467
 468                 parents = commit->parents;
 469                 if (!parents)
 470                         return;
 471
 472                 while ((parents = parents->next))
 473                         commit_list_insert(parents->item, plist);
 474
 475                 commit = commit->parents->item;
 476         }
 477 }
 478
 479 void clear_commit_marks(struct commit *commit, unsigned int mark)
 480 {
 481         struct commit_list *list = NULL;
 482         commit_list_insert(commit, &list);
 483         while (list)
 484                 clear_commit_marks_1(&list, pop_commit(&list), mark);
 485 }
 486
 487 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 488 {
 489         struct object *object;
 490         struct commit *commit;
 491         unsigned int i;
 492
 493         for (i = 0; i < a->nr; i++) {
 494                 object = a->objects[i].item;
 495                 commit = lookup_commit_reference_gently(object->sha1, 1);
 496                 if (commit)
 497                         clear_commit_marks(commit, mark);
 498         }
 499 }
 500
 501 struct commit *pop_commit(struct commit_list **stack)
 502 {
 503         struct commit_list *top = *stack;
 504         struct commit *item = top ? top->item : NULL;
 505
 506         if (top) {
 507                 *stack = top->next;
 508                 free(top);
 509         }
 510         return item;
 511 }
 512
 513 /*
 514  * Performs an in-place topological sort on the list supplied.
 515  */
 516 void sort_in_topological_order(struct commit_list ** list, int lifo)
 517 {
 518         struct commit_list *next, *orig = *list;
 519         struct commit_list *work, **insert;
 520         struct commit_list **pptr;
 521
 522         if (!orig)
 523                 return;
 524         *list = NULL;
 525
 526         /* Mark them and clear the indegree */
 527         for (next = orig; next; next = next->next) {
 528                 struct commit *commit = next->item;
 529                 commit->indegree = 1;
 530         }
 531
 532         /* update the indegree */
 533         for (next = orig; next; next = next->next) {
 534                 struct commit_list * parents = next->item->parents;
 535                 while (parents) {
 536                         struct commit *parent = parents->item;
 537
 538                         if (parent->indegree)
 539                                 parent->indegree++;
 540                         parents = parents->next;
 541                 }
 542         }
 543
 544         /*
 545          * find the tips
 546          *
 547          * tips are nodes not reachable from any other node in the list
 548          *
 549          * the tips serve as a starting set for the work queue.
 550          */
 551         work = NULL;
 552         insert = &work;
 553         for (next = orig; next; next = next->next) {
 554                 struct commit *commit = next->item;
 555
 556                 if (commit->indegree == 1)
 557                         insert = &commit_list_insert(commit, insert)->next;
 558         }
 559
 560         /* process the list in topological order */
 561         if (!lifo)
 562                 commit_list_sort_by_date(&work);
 563
 564         pptr = list;
 565         *list = NULL;
 566         while (work) {
 567                 struct commit *commit;
 568                 struct commit_list *parents, *work_item;
 569
 570                 work_item = work;
 571                 work = work_item->next;
 572                 work_item->next = NULL;
 573
 574                 commit = work_item->item;
 575                 for (parents = commit->parents; parents ; parents = parents->next) {
 576                         struct commit *parent = parents->item;
 577
 578                         if (!parent->indegree)
 579                                 continue;
 580
 581                         /*
 582                          * parents are only enqueued for emission
 583                          * when all their children have been emitted thereby
 584                          * guaranteeing topological order.
 585                          */
 586                         if (--parent->indegree == 1) {
 587                                 if (!lifo)
 588                                         commit_list_insert_by_date(parent, &work);
 589                                 else
 590                                         commit_list_insert(parent, &work);
 591                         }
 592                 }
 593                 /*
 594                  * work_item is a commit all of whose children
 595                  * have already been emitted. we can emit it now.
 596                  */
 597                 commit->indegree = 0;
 598                 *pptr = work_item;
 599                 pptr = &work_item->next;
 600         }
 601 }
 602
 603 /* merge-base stuff */
 604
 605 /* bits #0..15 in revision.h */
 606 #define PARENT1         (1u<<16)
 607 #define PARENT2         (1u<<17)
 608 #define STALE           (1u<<18)
 609 #define RESULT          (1u<<19)
 610
 611 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 612
 613 static struct commit *interesting(struct commit_list *list)
 614 {
 615         while (list) {
 616                 struct commit *commit = list->item;
 617                 list = list->next;
 618                 if (commit->object.flags & STALE)
 619                         continue;
 620                 return commit;
 621         }
 622         return NULL;
 623 }
 624
 625 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 626 {
 627         struct commit_list *list = NULL;
 628         struct commit_list *result = NULL;
 629         int i;
 630
 631         for (i = 0; i < n; i++) {
 632                 if (one == twos[i])
 633                         /*
 634                          * We do not mark this even with RESULT so we do not
 635                          * have to clean it up.
 636                          */
 637                         return commit_list_insert(one, &result);
 638         }
 639
 640         if (parse_commit(one))
 641                 return NULL;
 642         for (i = 0; i < n; i++) {
 643                 if (parse_commit(twos[i]))
 644                         return NULL;
 645         }
 646
 647         one->object.flags |= PARENT1;
 648         commit_list_insert_by_date(one, &list);
 649         for (i = 0; i < n; i++) {
 650                 twos[i]->object.flags |= PARENT2;
 651                 commit_list_insert_by_date(twos[i], &list);
 652         }
 653
 654         while (interesting(list)) {
 655                 struct commit *commit;
 656                 struct commit_list *parents;
 657                 struct commit_list *next;
 658                 int flags;
 659
 660                 commit = list->item;
 661                 next = list->next;
 662                 free(list);
 663                 list = next;
 664
 665                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 666                 if (flags == (PARENT1 | PARENT2)) {
 667                         if (!(commit->object.flags & RESULT)) {
 668                                 commit->object.flags |= RESULT;
 669                                 commit_list_insert_by_date(commit, &result);
 670                         }
 671                         /* Mark parents of a found merge stale */
 672                         flags |= STALE;
 673                 }
 674                 parents = commit->parents;
 675                 while (parents) {
 676                         struct commit *p = parents->item;
 677                         parents = parents->next;
 678                         if ((p->object.flags & flags) == flags)
 679                                 continue;
 680                         if (parse_commit(p))
 681                                 return NULL;
 682                         p->object.flags |= flags;
 683                         commit_list_insert_by_date(p, &list);
 684                 }
 685         }
 686
 687         /* Clean up the result to remove stale ones */
 688         free_commit_list(list);
 689         list = result; result = NULL;
 690         while (list) {
 691                 struct commit_list *next = list->next;
 692                 if (!(list->item->object.flags & STALE))
 693                         commit_list_insert_by_date(list->item, &result);
 694                 free(list);
 695                 list = next;
 696         }
 697         return result;
 698 }
 699
 700 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 701 {
 702         struct commit_list *i, *j, *k, *ret = NULL;
 703         struct commit_list **pptr = &ret;
 704
 705         for (i = in; i; i = i->next) {
 706                 if (!ret)
 707                         pptr = &commit_list_insert(i->item, pptr)->next;
 708                 else {
 709                         struct commit_list *new = NULL, *end = NULL;
 710
 711                         for (j = ret; j; j = j->next) {
 712                                 struct commit_list *bases;
 713                                 bases = get_merge_bases(i->item, j->item, 1);
 714                                 if (!new)
 715                                         new = bases;
 716                                 else
 717                                         end->next = bases;
 718                                 for (k = bases; k; k = k->next)
 719                                         end = k;
 720                         }
 721                         ret = new;
 722                 }
 723         }
 724         return ret;
 725 }
 726
 727 struct commit_list *get_merge_bases_many(struct commit *one,
 728                                          int n,
 729                                          struct commit **twos,
 730                                          int cleanup)
 731 {
 732         struct commit_list *list;
 733         struct commit **rslt;
 734         struct commit_list *result;
 735         int cnt, i, j;
 736
 737         result = merge_bases_many(one, n, twos);
 738         for (i = 0; i < n; i++) {
 739                 if (one == twos[i])
 740                         return result;
 741         }
 742         if (!result || !result->next) {
 743                 if (cleanup) {
 744                         clear_commit_marks(one, all_flags);
 745                         for (i = 0; i < n; i++)
 746                                 clear_commit_marks(twos[i], all_flags);
 747                 }
 748                 return result;
 749         }
 750
 751         /* There are more than one */
 752         cnt = 0;
 753         list = result;
 754         while (list) {
 755                 list = list->next;
 756                 cnt++;
 757         }
 758         rslt = xcalloc(cnt, sizeof(*rslt));
 759         for (list = result, i = 0; list; list = list->next)
 760                 rslt[i++] = list->item;
 761         free_commit_list(result);
 762
 763         clear_commit_marks(one, all_flags);
 764         for (i = 0; i < n; i++)
 765                 clear_commit_marks(twos[i], all_flags);
 766         for (i = 0; i < cnt - 1; i++) {
 767                 for (j = i+1; j < cnt; j++) {
 768                         if (!rslt[i] || !rslt[j])
 769                                 continue;
 770                         result = merge_bases_many(rslt[i], 1, &rslt[j]);
 771                         clear_commit_marks(rslt[i], all_flags);
 772                         clear_commit_marks(rslt[j], all_flags);
 773                         for (list = result; list; list = list->next) {
 774                                 if (rslt[i] == list->item)
 775                                         rslt[i] = NULL;
 776                                 if (rslt[j] == list->item)
 777                                         rslt[j] = NULL;
 778                         }
 779                 }
 780         }
 781
 782         /* Surviving ones in rslt[] are the independent results */
 783         result = NULL;
 784         for (i = 0; i < cnt; i++) {
 785                 if (rslt[i])
 786                         commit_list_insert_by_date(rslt[i], &result);
 787         }
 788         free(rslt);
 789         return result;
 790 }
 791
 792 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 793                                     int cleanup)
 794 {
 795         return get_merge_bases_many(one, 1, &two, cleanup);
 796 }
 797
 798 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 799 {
 800         if (!with_commit)
 801                 return 1;
 802         while (with_commit) {
 803                 struct commit *other;
 804
 805                 other = with_commit->item;
 806                 with_commit = with_commit->next;
 807                 if (in_merge_bases(other, &commit, 1))
 808                         return 1;
 809         }
 810         return 0;
 811 }
 812
 813 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 814 {
 815         struct commit_list *bases, *b;
 816         int ret = 0;
 817
 818         if (num == 1)
 819                 bases = get_merge_bases(commit, *reference, 1);
 820         else
 821                 die("not yet");
 822         for (b = bases; b; b = b->next) {
 823                 if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 824                         ret = 1;
 825                         break;
 826                 }
 827         }
 828
 829         free_commit_list(bases);
 830         return ret;
 831 }
 832
 833 struct commit_list *reduce_heads(struct commit_list *heads)
 834 {
 835         struct commit_list *p;
 836         struct commit_list *result = NULL, **tail = &result;
 837         struct commit **other;
 838         size_t num_head, num_other;
 839
 840         if (!heads)
 841                 return NULL;
 842
 843         /* Avoid unnecessary reallocations */
 844         for (p = heads, num_head = 0; p; p = p->next)
 845                 num_head++;
 846         other = xcalloc(sizeof(*other), num_head);
 847
 848         /* For each commit, see if it can be reached by others */
 849         for (p = heads; p; p = p->next) {
 850                 struct commit_list *q, *base;
 851
 852                 /* Do we already have this in the result? */
 853                 for (q = result; q; q = q->next)
 854                         if (p->item == q->item)
 855                                 break;
 856                 if (q)
 857                         continue;
 858
 859                 num_other = 0;
 860                 for (q = heads; q; q = q->next) {
 861                         if (p->item == q->item)
 862                                 continue;
 863                         other[num_other++] = q->item;
 864                 }
 865                 if (num_other)
 866                         base = get_merge_bases_many(p->item, num_other, other, 1);
 867                 else
 868                         base = NULL;
 869                 /*
 870                  * If p->item does not have anything common with other
 871                  * commits, there won't be any merge base.  If it is
 872                  * reachable from some of the others, p->item will be
 873                  * the merge base.  If its history is connected with
 874                  * others, but p->item is not reachable by others, we
 875                  * will get something other than p->item back.
 876                  */
 877                 if (!base || (base->item != p->item))
 878                         tail = &(commit_list_insert(p->item, tail)->next);
 879                 free_commit_list(base);
 880         }
 881         free(other);
 882         return result;
 883 }
 884
 885 static const char gpg_sig_header[] = "gpgsig";
 886 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 887
 888 static int do_sign_commit(struct strbuf *buf, const char *keyid)
 889 {
 890         struct strbuf sig = STRBUF_INIT;
 891         int inspos, copypos;
 892
 893         /* find the end of the header */
 894         inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
 895
 896         if (!keyid || !*keyid)
 897                 keyid = get_signing_key();
 898         if (sign_buffer(buf, &sig, keyid)) {
 899                 strbuf_release(&sig);
 900                 return -1;
 901         }
 902
 903         for (copypos = 0; sig.buf[copypos]; ) {
 904                 const char *bol = sig.buf + copypos;
 905                 const char *eol = strchrnul(bol, '\n');
 906                 int len = (eol - bol) + !!*eol;
 907
 908                 if (!copypos) {
 909                         strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
 910                         inspos += gpg_sig_header_len;
 911                 }
 912                 strbuf_insert(buf, inspos++, " ", 1);
 913                 strbuf_insert(buf, inspos, bol, len);
 914                 inspos += len;
 915                 copypos += len;
 916         }
 917         strbuf_release(&sig);
 918         return 0;
 919 }
 920
 921 int parse_signed_commit(const unsigned char *sha1,
 922                         struct strbuf *payload, struct strbuf *signature)
 923 {
 924         unsigned long size;
 925         enum object_type type;
 926         char *buffer = read_sha1_file(sha1, &type, &size);
 927         int in_signature, saw_signature = -1;
 928         char *line, *tail;
 929
 930         if (!buffer || type != OBJ_COMMIT)
 931                 goto cleanup;
 932
 933         line = buffer;
 934         tail = buffer + size;
 935         in_signature = 0;
 936         saw_signature = 0;
 937         while (line < tail) {
 938                 const char *sig = NULL;
 939                 char *next = memchr(line, '\n', tail - line);
 940
 941                 next = next ? next + 1 : tail;
 942                 if (in_signature && line[0] == ' ')
 943                         sig = line + 1;
 944                 else if (!prefixcmp(line, gpg_sig_header) &&
 945                          line[gpg_sig_header_len] == ' ')
 946                         sig = line + gpg_sig_header_len + 1;
 947                 if (sig) {
 948                         strbuf_add(signature, sig, next - sig);
 949                         saw_signature = 1;
 950                         in_signature = 1;
 951                 } else {
 952                         if (*line == '\n')
 953                                 /* dump the whole remainder of the buffer */
 954                                 next = tail;
 955                         strbuf_add(payload, line, next - line);
 956                         in_signature = 0;
 957                 }
 958                 line = next;
 959         }
 960  cleanup:
 961         free(buffer);
 962         return saw_signature;
 963 }
 964
 965 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 966 {
 967         struct merge_remote_desc *desc;
 968         struct commit_extra_header *mergetag;
 969         char *buf;
 970         unsigned long size, len;
 971         enum object_type type;
 972
 973         desc = merge_remote_util(parent);
 974         if (!desc || !desc->obj)
 975                 return;
 976         buf = read_sha1_file(desc->obj->sha1, &type, &size);
 977         if (!buf || type != OBJ_TAG)
 978                 goto free_return;
 979         len = parse_signature(buf, size);
 980         if (size == len)
 981                 goto free_return;
 982         /*
 983          * We could verify this signature and either omit the tag when
 984          * it does not validate, but the integrator may not have the
 985          * public key of the signer of the tag he is merging, while a
 986          * later auditor may have it while auditing, so let's not run
 987          * verify-signed-buffer here for now...
 988          *
 989          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 990          *      warn("warning: signed tag unverified.");
 991          */
 992         mergetag = xcalloc(1, sizeof(*mergetag));
 993         mergetag->key = xstrdup("mergetag");
 994         mergetag->value = buf;
 995         mergetag->len = size;
 996
 997         **tail = mergetag;
 998         *tail = &mergetag->next;
 999         return;
1000
1001 free_return:
1002         free(buf);
1003 }
1004
1005 void append_merge_tag_headers(struct commit_list *parents,
1006                               struct commit_extra_header ***tail)
1007 {
1008         while (parents) {
1009                 struct commit *parent = parents->item;
1010                 handle_signed_tag(parent, tail);
1011                 parents = parents->next;
1012         }
1013 }
1014
1015 static void add_extra_header(struct strbuf *buffer,
1016                              struct commit_extra_header *extra)
1017 {
1018         strbuf_addstr(buffer, extra->key);
1019         if (extra->len)
1020                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
1021         else
1022                 strbuf_addch(buffer, '\n');
1023 }
1024
1025 struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1026                                                       const char **exclude)
1027 {
1028         struct commit_extra_header *extra = NULL;
1029         unsigned long size;
1030         enum object_type type;
1031         char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1032         if (buffer && type == OBJ_COMMIT)
1033                 extra = read_commit_extra_header_lines(buffer, size, exclude);
1034         free(buffer);
1035         return extra;
1036 }
1037
1038 static inline int standard_header_field(const char *field, size_t len)
1039 {
1040         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1041                 (len == 6 && !memcmp(field, "parent ", 7)) ||
1042                 (len == 6 && !memcmp(field, "author ", 7)) ||
1043                 (len == 9 && !memcmp(field, "committer ", 10)) ||
1044                 (len == 8 && !memcmp(field, "encoding ", 9)));
1045 }
1046
1047 static int excluded_header_field(const char *field, size_t len, const char **exclude)
1048 {
1049         if (!exclude)
1050                 return 0;
1051
1052         while (*exclude) {
1053                 size_t xlen = strlen(*exclude);
1054                 if (len == xlen &&
1055                     !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1056                         return 1;
1057                 exclude++;
1058         }
1059         return 0;
1060 }
1061
1062 struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size,
1063                                                            const char **exclude)
1064 {
1065         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1066         const char *line, *next, *eof, *eob;
1067         struct strbuf buf = STRBUF_INIT;
1068
1069         for (line = buffer, eob = line + size;
1070              line < eob && *line != '\n';
1071              line = next) {
1072                 next = memchr(line, '\n', eob - line);
1073                 next = next ? next + 1 : eob;
1074                 if (*line == ' ') {
1075                         /* continuation */
1076                         if (it)
1077                                 strbuf_add(&buf, line + 1, next - (line + 1));
1078                         continue;
1079                 }
1080                 if (it)
1081                         it->value = strbuf_detach(&buf, &it->len);
1082                 strbuf_reset(&buf);
1083                 it = NULL;
1084
1085                 eof = strchr(line, ' ');
1086                 if (next <= eof)
1087                         eof = next;
1088
1089                 if (standard_header_field(line, eof - line) ||
1090                     excluded_header_field(line, eof - line, exclude))
1091                         continue;
1092
1093                 it = xcalloc(1, sizeof(*it));
1094                 it->key = xmemdupz(line, eof-line);
1095                 *tail = it;
1096                 tail = &it->next;
1097                 if (eof + 1 < next)
1098                         strbuf_add(&buf, eof + 1, next - (eof + 1));
1099         }
1100         if (it)
1101                 it->value = strbuf_detach(&buf, &it->len);
1102         return extra;
1103 }
1104
1105 void free_commit_extra_headers(struct commit_extra_header *extra)
1106 {
1107         while (extra) {
1108                 struct commit_extra_header *next = extra->next;
1109                 free(extra->key);
1110                 free(extra->value);
1111                 free(extra);
1112                 extra = next;
1113         }
1114 }
1115
1116 int commit_tree(const struct strbuf *msg, unsigned char *tree,
1117                 struct commit_list *parents, unsigned char *ret,
1118                 const char *author, const char *sign_commit)
1119 {
1120         struct commit_extra_header *extra = NULL, **tail = &extra;
1121         int result;
1122
1123         append_merge_tag_headers(parents, &tail);
1124         result = commit_tree_extended(msg, tree, parents, ret,
1125                                       author, sign_commit, extra);
1126         free_commit_extra_headers(extra);
1127         return result;
1128 }
1129
1130 static const char commit_utf8_warn[] =
1131 "Warning: commit message does not conform to UTF-8.\n"
1132 "You may want to amend it after fixing the message, or set the config\n"
1133 "variable i18n.commitencoding to the encoding your project uses.\n";
1134
1135 int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1136                          struct commit_list *parents, unsigned char *ret,
1137                          const char *author, const char *sign_commit,
1138                          struct commit_extra_header *extra)
1139 {
1140         int result;
1141         int encoding_is_utf8;
1142         struct strbuf buffer;
1143
1144         assert_sha1_type(tree, OBJ_TREE);
1145
1146         if (memchr(msg->buf, '\0', msg->len))
1147                 return error("a NUL byte in commit log message not allowed.");
1148
1149         /* Not having i18n.commitencoding is the same as having utf-8 */
1150         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1151
1152         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1153         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1154
1155         /*
1156          * NOTE! This ordering means that the same exact tree merged with a
1157          * different order of parents will be a _different_ changeset even
1158          * if everything else stays the same.
1159          */
1160         while (parents) {
1161                 struct commit_list *next = parents->next;
1162                 struct commit *parent = parents->item;
1163
1164                 strbuf_addf(&buffer, "parent %s\n",
1165                             sha1_to_hex(parent->object.sha1));
1166                 free(parents);
1167                 parents = next;
1168         }
1169
1170         /* Person/date information */
1171         if (!author)
1172                 author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1173         strbuf_addf(&buffer, "author %s\n", author);
1174         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1175         if (!encoding_is_utf8)
1176                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1177
1178         while (extra) {
1179                 add_extra_header(&buffer, extra);
1180                 extra = extra->next;
1181         }
1182         strbuf_addch(&buffer, '\n');
1183
1184         /* And add the comment */
1185         strbuf_addbuf(&buffer, msg);
1186
1187         /* And check the encoding */
1188         if (encoding_is_utf8 && !is_utf8(buffer.buf))
1189                 fprintf(stderr, commit_utf8_warn);
1190
1191         if (sign_commit && do_sign_commit(&buffer, sign_commit))
1192                 return -1;
1193
1194         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1195         strbuf_release(&buffer);
1196         return result;
1197 }
1198
1199 struct commit *get_merge_parent(const char *name)
1200 {
1201         struct object *obj;
1202         struct commit *commit;
1203         unsigned char sha1[20];
1204         if (get_sha1(name, sha1))
1205                 return NULL;
1206         obj = parse_object(sha1);
1207         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1208         if (commit && !commit->util) {
1209                 struct merge_remote_desc *desc;
1210                 desc = xmalloc(sizeof(*desc));
1211                 desc->obj = obj;
1212                 desc->name = strdup(name);
1213                 commit->util = desc;
1214         }
1215         return commit;
1216 }