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 #include "commit-slab.h"
  12 #include "prio-queue.h"
  13
  14 static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  15
  16 int save_commit_buffer = 1;
  17
  18 const char *commit_type = "commit";
  19 static int commit_count;
  20
  21 static struct commit *check_commit(struct object *obj,
  22                                    const unsigned char *sha1,
  23                                    int quiet)
  24 {
  25         if (obj->type != OBJ_COMMIT) {
  26                 if (!quiet)
  27                         error("Object %s is a %s, not a commit",
  28                               sha1_to_hex(sha1), typename(obj->type));
  29                 return NULL;
  30         }
  31         return (struct commit *) obj;
  32 }
  33
  34 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  35                                               int quiet)
  36 {
  37         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  38
  39         if (!obj)
  40                 return NULL;
  41         return check_commit(obj, sha1, quiet);
  42 }
  43
  44 struct commit *lookup_commit_reference(const unsigned char *sha1)
  45 {
  46         return lookup_commit_reference_gently(sha1, 0);
  47 }
  48
  49 struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  50 {
  51         struct commit *c = lookup_commit_reference(sha1);
  52         if (!c)
  53                 die(_("could not parse %s"), ref_name);
  54         if (hashcmp(sha1, c->object.sha1)) {
  55                 warning(_("%s %s is not a commit!"),
  56                         ref_name, sha1_to_hex(sha1));
  57         }
  58         return c;
  59 }
  60
  61 struct commit *lookup_commit(const unsigned char *sha1)
  62 {
  63         struct object *obj = lookup_object(sha1);
  64         if (!obj) {
  65                 struct commit *c = alloc_commit_node();
  66                 c->index = commit_count++;
  67                 return create_object(sha1, OBJ_COMMIT, c);
  68         }
  69         if (!obj->type)
  70                 obj->type = OBJ_COMMIT;
  71         return check_commit(obj, sha1, 0);
  72 }
  73
  74 struct commit *lookup_commit_reference_by_name(const char *name)
  75 {
  76         unsigned char sha1[20];
  77         struct commit *commit;
  78
  79         if (get_sha1_committish(name, sha1))
  80                 return NULL;
  81         commit = lookup_commit_reference(sha1);
  82         if (!commit || parse_commit(commit))
  83                 return NULL;
  84         return commit;
  85 }
  86
  87 static unsigned long parse_commit_date(const char *buf, const char *tail)
  88 {
  89         const char *dateptr;
  90
  91         if (buf + 6 >= tail)
  92                 return 0;
  93         if (memcmp(buf, "author", 6))
  94                 return 0;
  95         while (buf < tail && *buf++ != '\n')
  96                 /* nada */;
  97         if (buf + 9 >= tail)
  98                 return 0;
  99         if (memcmp(buf, "committer", 9))
 100                 return 0;
 101         while (buf < tail && *buf++ != '>')
 102                 /* nada */;
 103         if (buf >= tail)
 104                 return 0;
 105         dateptr = buf;
 106         while (buf < tail && *buf++ != '\n')
 107                 /* nada */;
 108         if (buf >= tail)
 109                 return 0;
 110         /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 111         return strtoul(dateptr, NULL, 10);
 112 }
 113
 114 static struct commit_graft **commit_graft;
 115 static int commit_graft_alloc, commit_graft_nr;
 116
 117 static int commit_graft_pos(const unsigned char *sha1)
 118 {
 119         int lo, hi;
 120         lo = 0;
 121         hi = commit_graft_nr;
 122         while (lo < hi) {
 123                 int mi = (lo + hi) / 2;
 124                 struct commit_graft *graft = commit_graft[mi];
 125                 int cmp = hashcmp(sha1, graft->sha1);
 126                 if (!cmp)
 127                         return mi;
 128                 if (cmp < 0)
 129                         hi = mi;
 130                 else
 131                         lo = mi + 1;
 132         }
 133         return -lo - 1;
 134 }
 135
 136 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 137 {
 138         int pos = commit_graft_pos(graft->sha1);
 139
 140         if (0 <= pos) {
 141                 if (ignore_dups)
 142                         free(graft);
 143                 else {
 144                         free(commit_graft[pos]);
 145                         commit_graft[pos] = graft;
 146                 }
 147                 return 1;
 148         }
 149         pos = -pos - 1;
 150         if (commit_graft_alloc <= ++commit_graft_nr) {
 151                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 152                 commit_graft = xrealloc(commit_graft,
 153                                         sizeof(*commit_graft) *
 154                                         commit_graft_alloc);
 155         }
 156         if (pos < commit_graft_nr)
 157                 memmove(commit_graft + pos + 1,
 158                         commit_graft + pos,
 159                         (commit_graft_nr - pos - 1) *
 160                         sizeof(*commit_graft));
 161         commit_graft[pos] = graft;
 162         return 0;
 163 }
 164
 165 struct commit_graft *read_graft_line(char *buf, int len)
 166 {
 167         /* The format is just "Commit Parent1 Parent2 ...\n" */
 168         int i;
 169         struct commit_graft *graft = NULL;
 170
 171         while (len && isspace(buf[len-1]))
 172                 buf[--len] = '\0';
 173         if (buf[0] == '#' || buf[0] == '\0')
 174                 return NULL;
 175         if ((len + 1) % 41)
 176                 goto bad_graft_data;
 177         i = (len + 1) / 41 - 1;
 178         graft = xmalloc(sizeof(*graft) + 20 * i);
 179         graft->nr_parent = i;
 180         if (get_sha1_hex(buf, graft->sha1))
 181                 goto bad_graft_data;
 182         for (i = 40; i < len; i += 41) {
 183                 if (buf[i] != ' ')
 184                         goto bad_graft_data;
 185                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 186                         goto bad_graft_data;
 187         }
 188         return graft;
 189
 190 bad_graft_data:
 191         error("bad graft data: %s", buf);
 192         free(graft);
 193         return NULL;
 194 }
 195
 196 static int read_graft_file(const char *graft_file)
 197 {
 198         FILE *fp = fopen(graft_file, "r");
 199         char buf[1024];
 200         if (!fp)
 201                 return -1;
 202         while (fgets(buf, sizeof(buf), fp)) {
 203                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 204                 int len = strlen(buf);
 205                 struct commit_graft *graft = read_graft_line(buf, len);
 206                 if (!graft)
 207                         continue;
 208                 if (register_commit_graft(graft, 1))
 209                         error("duplicate graft data: %s", buf);
 210         }
 211         fclose(fp);
 212         return 0;
 213 }
 214
 215 static void prepare_commit_graft(void)
 216 {
 217         static int commit_graft_prepared;
 218         char *graft_file;
 219
 220         if (commit_graft_prepared)
 221                 return;
 222         graft_file = get_graft_file();
 223         read_graft_file(graft_file);
 224         /* make sure shallows are read */
 225         is_repository_shallow();
 226         commit_graft_prepared = 1;
 227 }
 228
 229 struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 230 {
 231         int pos;
 232         prepare_commit_graft();
 233         pos = commit_graft_pos(sha1);
 234         if (pos < 0)
 235                 return NULL;
 236         return commit_graft[pos];
 237 }
 238
 239 int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 240 {
 241         int i, ret;
 242         for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 243                 ret = fn(commit_graft[i], cb_data);
 244         return ret;
 245 }
 246
 247 int unregister_shallow(const unsigned char *sha1)
 248 {
 249         int pos = commit_graft_pos(sha1);
 250         if (pos < 0)
 251                 return -1;
 252         if (pos + 1 < commit_graft_nr)
 253                 memmove(commit_graft + pos, commit_graft + pos + 1,
 254                                 sizeof(struct commit_graft *)
 255                                 * (commit_graft_nr - pos - 1));
 256         commit_graft_nr--;
 257         return 0;
 258 }
 259
 260 int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 261 {
 262         const char *tail = buffer;
 263         const char *bufptr = buffer;
 264         unsigned char parent[20];
 265         struct commit_list **pptr;
 266         struct commit_graft *graft;
 267
 268         if (item->object.parsed)
 269                 return 0;
 270         item->object.parsed = 1;
 271         tail += size;
 272         if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 273                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 274         if (get_sha1_hex(bufptr + 5, parent) < 0)
 275                 return error("bad tree pointer in commit %s",
 276                              sha1_to_hex(item->object.sha1));
 277         item->tree = lookup_tree(parent);
 278         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 279         pptr = &item->parents;
 280
 281         graft = lookup_commit_graft(item->object.sha1);
 282         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 283                 struct commit *new_parent;
 284
 285                 if (tail <= bufptr + 48 ||
 286                     get_sha1_hex(bufptr + 7, parent) ||
 287                     bufptr[47] != '\n')
 288                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 289                 bufptr += 48;
 290                 /*
 291                  * The clone is shallow if nr_parent < 0, and we must
 292                  * not traverse its real parents even when we unhide them.
 293                  */
 294                 if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 295                         continue;
 296                 new_parent = lookup_commit(parent);
 297                 if (new_parent)
 298                         pptr = &commit_list_insert(new_parent, pptr)->next;
 299         }
 300         if (graft) {
 301                 int i;
 302                 struct commit *new_parent;
 303                 for (i = 0; i < graft->nr_parent; i++) {
 304                         new_parent = lookup_commit(graft->parent[i]);
 305                         if (!new_parent)
 306                                 continue;
 307                         pptr = &commit_list_insert(new_parent, pptr)->next;
 308                 }
 309         }
 310         item->date = parse_commit_date(bufptr, tail);
 311
 312         return 0;
 313 }
 314
 315 int parse_commit(struct commit *item)
 316 {
 317         enum object_type type;
 318         void *buffer;
 319         unsigned long size;
 320         int ret;
 321
 322         if (!item)
 323                 return -1;
 324         if (item->object.parsed)
 325                 return 0;
 326         buffer = read_sha1_file(item->object.sha1, &type, &size);
 327         if (!buffer)
 328                 return error("Could not read %s",
 329                              sha1_to_hex(item->object.sha1));
 330         if (type != OBJ_COMMIT) {
 331                 free(buffer);
 332                 return error("Object %s not a commit",
 333                              sha1_to_hex(item->object.sha1));
 334         }
 335         ret = parse_commit_buffer(item, buffer, size);
 336         if (save_commit_buffer && !ret) {
 337                 item->buffer = buffer;
 338                 return 0;
 339         }
 340         free(buffer);
 341         return ret;
 342 }
 343
 344 int find_commit_subject(const char *commit_buffer, const char **subject)
 345 {
 346         const char *eol;
 347         const char *p = commit_buffer;
 348
 349         while (*p && (*p != '\n' || p[1] != '\n'))
 350                 p++;
 351         if (*p) {
 352                 p += 2;
 353                 for (eol = p; *eol && *eol != '\n'; eol++)
 354                         ; /* do nothing */
 355         } else
 356                 eol = p;
 357
 358         *subject = p;
 359
 360         return eol - p;
 361 }
 362
 363 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 364 {
 365         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 366         new_list->item = item;
 367         new_list->next = *list_p;
 368         *list_p = new_list;
 369         return new_list;
 370 }
 371
 372 unsigned commit_list_count(const struct commit_list *l)
 373 {
 374         unsigned c = 0;
 375         for (; l; l = l->next )
 376                 c++;
 377         return c;
 378 }
 379
 380 void free_commit_list(struct commit_list *list)
 381 {
 382         while (list) {
 383                 struct commit_list *temp = list;
 384                 list = temp->next;
 385                 free(temp);
 386         }
 387 }
 388
 389 struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 390 {
 391         struct commit_list **pp = list;
 392         struct commit_list *p;
 393         while ((p = *pp) != NULL) {
 394                 if (p->item->date < item->date) {
 395                         break;
 396                 }
 397                 pp = &p->next;
 398         }
 399         return commit_list_insert(item, pp);
 400 }
 401
 402 static int commit_list_compare_by_date(const void *a, const void *b)
 403 {
 404         unsigned long a_date = ((const struct commit_list *)a)->item->date;
 405         unsigned long b_date = ((const struct commit_list *)b)->item->date;
 406         if (a_date < b_date)
 407                 return 1;
 408         if (a_date > b_date)
 409                 return -1;
 410         return 0;
 411 }
 412
 413 static void *commit_list_get_next(const void *a)
 414 {
 415         return ((const struct commit_list *)a)->next;
 416 }
 417
 418 static void commit_list_set_next(void *a, void *next)
 419 {
 420         ((struct commit_list *)a)->next = next;
 421 }
 422
 423 void commit_list_sort_by_date(struct commit_list **list)
 424 {
 425         *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 426                                 commit_list_compare_by_date);
 427 }
 428
 429 struct commit *pop_most_recent_commit(struct commit_list **list,
 430                                       unsigned int mark)
 431 {
 432         struct commit *ret = (*list)->item;
 433         struct commit_list *parents = ret->parents;
 434         struct commit_list *old = *list;
 435
 436         *list = (*list)->next;
 437         free(old);
 438
 439         while (parents) {
 440                 struct commit *commit = parents->item;
 441                 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 442                         commit->object.flags |= mark;
 443                         commit_list_insert_by_date(commit, list);
 444                 }
 445                 parents = parents->next;
 446         }
 447         return ret;
 448 }
 449
 450 static void clear_commit_marks_1(struct commit_list **plist,
 451                                  struct commit *commit, unsigned int mark)
 452 {
 453         while (commit) {
 454                 struct commit_list *parents;
 455
 456                 if (!(mark & commit->object.flags))
 457                         return;
 458
 459                 commit->object.flags &= ~mark;
 460
 461                 parents = commit->parents;
 462                 if (!parents)
 463                         return;
 464
 465                 while ((parents = parents->next))
 466                         commit_list_insert(parents->item, plist);
 467
 468                 commit = commit->parents->item;
 469         }
 470 }
 471
 472 void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 473 {
 474         struct commit_list *list = NULL;
 475
 476         while (nr--) {
 477                 commit_list_insert(*commit, &list);
 478                 commit++;
 479         }
 480         while (list)
 481                 clear_commit_marks_1(&list, pop_commit(&list), mark);
 482 }
 483
 484 void clear_commit_marks(struct commit *commit, unsigned int mark)
 485 {
 486         clear_commit_marks_many(1, &commit, mark);
 487 }
 488
 489 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 490 {
 491         struct object *object;
 492         struct commit *commit;
 493         unsigned int i;
 494
 495         for (i = 0; i < a->nr; i++) {
 496                 object = a->objects[i].item;
 497                 commit = lookup_commit_reference_gently(object->sha1, 1);
 498                 if (commit)
 499                         clear_commit_marks(commit, mark);
 500         }
 501 }
 502
 503 struct commit *pop_commit(struct commit_list **stack)
 504 {
 505         struct commit_list *top = *stack;
 506         struct commit *item = top ? top->item : NULL;
 507
 508         if (top) {
 509                 *stack = top->next;
 510                 free(top);
 511         }
 512         return item;
 513 }
 514
 515 /*
 516  * Topological sort support
 517  */
 518
 519 /* count number of children that have not been emitted */
 520 define_commit_slab(indegree_slab, int);
 521
 522 /* record author-date for each commit object */
 523 define_commit_slab(author_date_slab, unsigned long);
 524
 525 static void record_author_date(struct author_date_slab *author_date,
 526                                struct commit *commit)
 527 {
 528         const char *buf, *line_end;
 529         char *buffer = NULL;
 530         struct ident_split ident;
 531         char *date_end;
 532         unsigned long date;
 533
 534         if (!commit->buffer) {
 535                 unsigned long size;
 536                 enum object_type type;
 537                 buffer = read_sha1_file(commit->object.sha1, &type, &size);
 538                 if (!buffer)
 539                         return;
 540         }
 541
 542         for (buf = commit->buffer ? commit->buffer : buffer;
 543              buf;
 544              buf = line_end + 1) {
 545                 line_end = strchrnul(buf, '\n');
 546                 if (prefixcmp(buf, "author ")) {
 547                         if (!line_end[0] || line_end[1] == '\n')
 548                                 return; /* end of header */
 549                         continue;
 550                 }
 551                 if (split_ident_line(&ident,
 552                                      buf + strlen("author "),
 553                                      line_end - (buf + strlen("author "))) ||
 554                     !ident.date_begin || !ident.date_end)
 555                         goto fail_exit; /* malformed "author" line */
 556                 break;
 557         }
 558
 559         date = strtoul(ident.date_begin, &date_end, 10);
 560         if (date_end != ident.date_end)
 561                 goto fail_exit; /* malformed date */
 562         *(author_date_slab_at(author_date, commit)) = date;
 563
 564 fail_exit:
 565         free(buffer);
 566 }
 567
 568 static int compare_commits_by_author_date(const void *a_, const void *b_,
 569                                           void *cb_data)
 570 {
 571         const struct commit *a = a_, *b = b_;
 572         struct author_date_slab *author_date = cb_data;
 573         unsigned long a_date = *(author_date_slab_at(author_date, a));
 574         unsigned long b_date = *(author_date_slab_at(author_date, b));
 575
 576         /* newer commits with larger date first */
 577         if (a_date < b_date)
 578                 return 1;
 579         else if (a_date > b_date)
 580                 return -1;
 581         return 0;
 582 }
 583
 584 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 585 {
 586         const struct commit *a = a_, *b = b_;
 587         /* newer commits with larger date first */
 588         if (a->date < b->date)
 589                 return 1;
 590         else if (a->date > b->date)
 591                 return -1;
 592         return 0;
 593 }
 594
 595 /*
 596  * Performs an in-place topological sort on the list supplied.
 597  */
 598 void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 599 {
 600         struct commit_list *next, *orig = *list;
 601         struct commit_list **pptr;
 602         struct indegree_slab indegree;
 603         struct prio_queue queue;
 604         struct commit *commit;
 605         struct author_date_slab author_date;
 606
 607         if (!orig)
 608                 return;
 609         *list = NULL;
 610
 611         init_indegree_slab(&indegree);
 612         memset(&queue, '\0', sizeof(queue));
 613
 614         switch (sort_order) {
 615         default: /* REV_SORT_IN_GRAPH_ORDER */
 616                 queue.compare = NULL;
 617                 break;
 618         case REV_SORT_BY_COMMIT_DATE:
 619                 queue.compare = compare_commits_by_commit_date;
 620                 break;
 621         case REV_SORT_BY_AUTHOR_DATE:
 622                 init_author_date_slab(&author_date);
 623                 queue.compare = compare_commits_by_author_date;
 624                 queue.cb_data = &author_date;
 625                 break;
 626         }
 627
 628         /* Mark them and clear the indegree */
 629         for (next = orig; next; next = next->next) {
 630                 struct commit *commit = next->item;
 631                 *(indegree_slab_at(&indegree, commit)) = 1;
 632                 /* also record the author dates, if needed */
 633                 if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 634                         record_author_date(&author_date, commit);
 635         }
 636
 637         /* update the indegree */
 638         for (next = orig; next; next = next->next) {
 639                 struct commit_list *parents = next->item->parents;
 640                 while (parents) {
 641                         struct commit *parent = parents->item;
 642                         int *pi = indegree_slab_at(&indegree, parent);
 643
 644                         if (*pi)
 645                                 (*pi)++;
 646                         parents = parents->next;
 647                 }
 648         }
 649
 650         /*
 651          * find the tips
 652          *
 653          * tips are nodes not reachable from any other node in the list
 654          *
 655          * the tips serve as a starting set for the work queue.
 656          */
 657         for (next = orig; next; next = next->next) {
 658                 struct commit *commit = next->item;
 659
 660                 if (*(indegree_slab_at(&indegree, commit)) == 1)
 661                         prio_queue_put(&queue, commit);
 662         }
 663
 664         /*
 665          * This is unfortunate; the initial tips need to be shown
 666          * in the order given from the revision traversal machinery.
 667          */
 668         if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 669                 prio_queue_reverse(&queue);
 670
 671         /* We no longer need the commit list */
 672         free_commit_list(orig);
 673
 674         pptr = list;
 675         *list = NULL;
 676         while ((commit = prio_queue_get(&queue)) != NULL) {
 677                 struct commit_list *parents;
 678
 679                 for (parents = commit->parents; parents ; parents = parents->next) {
 680                         struct commit *parent = parents->item;
 681                         int *pi = indegree_slab_at(&indegree, parent);
 682
 683                         if (!*pi)
 684                                 continue;
 685
 686                         /*
 687                          * parents are only enqueued for emission
 688                          * when all their children have been emitted thereby
 689                          * guaranteeing topological order.
 690                          */
 691                         if (--(*pi) == 1)
 692                                 prio_queue_put(&queue, parent);
 693                 }
 694                 /*
 695                  * all children of commit have already been
 696                  * emitted. we can emit it now.
 697                  */
 698                 *(indegree_slab_at(&indegree, commit)) = 0;
 699
 700                 pptr = &commit_list_insert(commit, pptr)->next;
 701         }
 702
 703         clear_indegree_slab(&indegree);
 704         clear_prio_queue(&queue);
 705         if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 706                 clear_author_date_slab(&author_date);
 707 }
 708
 709 /* merge-base stuff */
 710
 711 /* bits #0..15 in revision.h */
 712 #define PARENT1         (1u<<16)
 713 #define PARENT2         (1u<<17)
 714 #define STALE           (1u<<18)
 715 #define RESULT          (1u<<19)
 716
 717 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 718
 719 static struct commit *interesting(struct commit_list *list)
 720 {
 721         while (list) {
 722                 struct commit *commit = list->item;
 723                 list = list->next;
 724                 if (commit->object.flags & STALE)
 725                         continue;
 726                 return commit;
 727         }
 728         return NULL;
 729 }
 730
 731 /* all input commits in one and twos[] must have been parsed! */
 732 static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 733 {
 734         struct commit_list *list = NULL;
 735         struct commit_list *result = NULL;
 736         int i;
 737
 738         one->object.flags |= PARENT1;
 739         commit_list_insert_by_date(one, &list);
 740         if (!n)
 741                 return list;
 742         for (i = 0; i < n; i++) {
 743                 twos[i]->object.flags |= PARENT2;
 744                 commit_list_insert_by_date(twos[i], &list);
 745         }
 746
 747         while (interesting(list)) {
 748                 struct commit *commit;
 749                 struct commit_list *parents;
 750                 struct commit_list *next;
 751                 int flags;
 752
 753                 commit = list->item;
 754                 next = list->next;
 755                 free(list);
 756                 list = next;
 757
 758                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 759                 if (flags == (PARENT1 | PARENT2)) {
 760                         if (!(commit->object.flags & RESULT)) {
 761                                 commit->object.flags |= RESULT;
 762                                 commit_list_insert_by_date(commit, &result);
 763                         }
 764                         /* Mark parents of a found merge stale */
 765                         flags |= STALE;
 766                 }
 767                 parents = commit->parents;
 768                 while (parents) {
 769                         struct commit *p = parents->item;
 770                         parents = parents->next;
 771                         if ((p->object.flags & flags) == flags)
 772                                 continue;
 773                         if (parse_commit(p))
 774                                 return NULL;
 775                         p->object.flags |= flags;
 776                         commit_list_insert_by_date(p, &list);
 777                 }
 778         }
 779
 780         free_commit_list(list);
 781         return result;
 782 }
 783
 784 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 785 {
 786         struct commit_list *list = NULL;
 787         struct commit_list *result = NULL;
 788         int i;
 789
 790         for (i = 0; i < n; i++) {
 791                 if (one == twos[i])
 792                         /*
 793                          * We do not mark this even with RESULT so we do not
 794                          * have to clean it up.
 795                          */
 796                         return commit_list_insert(one, &result);
 797         }
 798
 799         if (parse_commit(one))
 800                 return NULL;
 801         for (i = 0; i < n; i++) {
 802                 if (parse_commit(twos[i]))
 803                         return NULL;
 804         }
 805
 806         list = paint_down_to_common(one, n, twos);
 807
 808         while (list) {
 809                 struct commit_list *next = list->next;
 810                 if (!(list->item->object.flags & STALE))
 811                         commit_list_insert_by_date(list->item, &result);
 812                 free(list);
 813                 list = next;
 814         }
 815         return result;
 816 }
 817
 818 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 819 {
 820         struct commit_list *i, *j, *k, *ret = NULL;
 821         struct commit_list **pptr = &ret;
 822
 823         for (i = in; i; i = i->next) {
 824                 if (!ret)
 825                         pptr = &commit_list_insert(i->item, pptr)->next;
 826                 else {
 827                         struct commit_list *new = NULL, *end = NULL;
 828
 829                         for (j = ret; j; j = j->next) {
 830                                 struct commit_list *bases;
 831                                 bases = get_merge_bases(i->item, j->item, 1);
 832                                 if (!new)
 833                                         new = bases;
 834                                 else
 835                                         end->next = bases;
 836                                 for (k = bases; k; k = k->next)
 837                                         end = k;
 838                         }
 839                         ret = new;
 840                 }
 841         }
 842         return ret;
 843 }
 844
 845 static int remove_redundant(struct commit **array, int cnt)
 846 {
 847         /*
 848          * Some commit in the array may be an ancestor of
 849          * another commit.  Move such commit to the end of
 850          * the array, and return the number of commits that
 851          * are independent from each other.
 852          */
 853         struct commit **work;
 854         unsigned char *redundant;
 855         int *filled_index;
 856         int i, j, filled;
 857
 858         work = xcalloc(cnt, sizeof(*work));
 859         redundant = xcalloc(cnt, 1);
 860         filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 861
 862         for (i = 0; i < cnt; i++)
 863                 parse_commit(array[i]);
 864         for (i = 0; i < cnt; i++) {
 865                 struct commit_list *common;
 866
 867                 if (redundant[i])
 868                         continue;
 869                 for (j = filled = 0; j < cnt; j++) {
 870                         if (i == j || redundant[j])
 871                                 continue;
 872                         filled_index[filled] = j;
 873                         work[filled++] = array[j];
 874                 }
 875                 common = paint_down_to_common(array[i], filled, work);
 876                 if (array[i]->object.flags & PARENT2)
 877                         redundant[i] = 1;
 878                 for (j = 0; j < filled; j++)
 879                         if (work[j]->object.flags & PARENT1)
 880                                 redundant[filled_index[j]] = 1;
 881                 clear_commit_marks(array[i], all_flags);
 882                 for (j = 0; j < filled; j++)
 883                         clear_commit_marks(work[j], all_flags);
 884                 free_commit_list(common);
 885         }
 886
 887         /* Now collect the result */
 888         memcpy(work, array, sizeof(*array) * cnt);
 889         for (i = filled = 0; i < cnt; i++)
 890                 if (!redundant[i])
 891                         array[filled++] = work[i];
 892         for (j = filled, i = 0; i < cnt; i++)
 893                 if (redundant[i])
 894                         array[j++] = work[i];
 895         free(work);
 896         free(redundant);
 897         free(filled_index);
 898         return filled;
 899 }
 900
 901 struct commit_list *get_merge_bases_many(struct commit *one,
 902                                          int n,
 903                                          struct commit **twos,
 904                                          int cleanup)
 905 {
 906         struct commit_list *list;
 907         struct commit **rslt;
 908         struct commit_list *result;
 909         int cnt, i;
 910
 911         result = merge_bases_many(one, n, twos);
 912         for (i = 0; i < n; i++) {
 913                 if (one == twos[i])
 914                         return result;
 915         }
 916         if (!result || !result->next) {
 917                 if (cleanup) {
 918                         clear_commit_marks(one, all_flags);
 919                         clear_commit_marks_many(n, twos, all_flags);
 920                 }
 921                 return result;
 922         }
 923
 924         /* There are more than one */
 925         cnt = 0;
 926         list = result;
 927         while (list) {
 928                 list = list->next;
 929                 cnt++;
 930         }
 931         rslt = xcalloc(cnt, sizeof(*rslt));
 932         for (list = result, i = 0; list; list = list->next)
 933                 rslt[i++] = list->item;
 934         free_commit_list(result);
 935
 936         clear_commit_marks(one, all_flags);
 937         clear_commit_marks_many(n, twos, all_flags);
 938
 939         cnt = remove_redundant(rslt, cnt);
 940         result = NULL;
 941         for (i = 0; i < cnt; i++)
 942                 commit_list_insert_by_date(rslt[i], &result);
 943         free(rslt);
 944         return result;
 945 }
 946
 947 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 948                                     int cleanup)
 949 {
 950         return get_merge_bases_many(one, 1, &two, cleanup);
 951 }
 952
 953 /*
 954  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 955  */
 956 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 957 {
 958         if (!with_commit)
 959                 return 1;
 960         while (with_commit) {
 961                 struct commit *other;
 962
 963                 other = with_commit->item;
 964                 with_commit = with_commit->next;
 965                 if (in_merge_bases(other, commit))
 966                         return 1;
 967         }
 968         return 0;
 969 }
 970
 971 /*
 972  * Is "commit" an ancestor of one of the "references"?
 973  */
 974 int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 975 {
 976         struct commit_list *bases;
 977         int ret = 0, i;
 978
 979         if (parse_commit(commit))
 980                 return ret;
 981         for (i = 0; i < nr_reference; i++)
 982                 if (parse_commit(reference[i]))
 983                         return ret;
 984
 985         bases = paint_down_to_common(commit, nr_reference, reference);
 986         if (commit->object.flags & PARENT2)
 987                 ret = 1;
 988         clear_commit_marks(commit, all_flags);
 989         clear_commit_marks_many(nr_reference, reference, all_flags);
 990         free_commit_list(bases);
 991         return ret;
 992 }
 993
 994 /*
 995  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 996  */
 997 int in_merge_bases(struct commit *commit, struct commit *reference)
 998 {
 999         return in_merge_bases_many(commit, 1, &reference);
1000 }
1001
1002 struct commit_list *reduce_heads(struct commit_list *heads)
1003 {
1004         struct commit_list *p;
1005         struct commit_list *result = NULL, **tail = &result;
1006         struct commit **array;
1007         int num_head, i;
1008
1009         if (!heads)
1010                 return NULL;
1011
1012         /* Uniquify */
1013         for (p = heads; p; p = p->next)
1014                 p->item->object.flags &= ~STALE;
1015         for (p = heads, num_head = 0; p; p = p->next) {
1016                 if (p->item->object.flags & STALE)
1017                         continue;
1018                 p->item->object.flags |= STALE;
1019                 num_head++;
1020         }
1021         array = xcalloc(sizeof(*array), num_head);
1022         for (p = heads, i = 0; p; p = p->next) {
1023                 if (p->item->object.flags & STALE) {
1024                         array[i++] = p->item;
1025                         p->item->object.flags &= ~STALE;
1026                 }
1027         }
1028         num_head = remove_redundant(array, num_head);
1029         for (i = 0; i < num_head; i++)
1030                 tail = &commit_list_insert(array[i], tail)->next;
1031         return result;
1032 }
1033
1034 static const char gpg_sig_header[] = "gpgsig";
1035 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1036
1037 static int do_sign_commit(struct strbuf *buf, const char *keyid)
1038 {
1039         struct strbuf sig = STRBUF_INIT;
1040         int inspos, copypos;
1041
1042         /* find the end of the header */
1043         inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1044
1045         if (!keyid || !*keyid)
1046                 keyid = get_signing_key();
1047         if (sign_buffer(buf, &sig, keyid)) {
1048                 strbuf_release(&sig);
1049                 return -1;
1050         }
1051
1052         for (copypos = 0; sig.buf[copypos]; ) {
1053                 const char *bol = sig.buf + copypos;
1054                 const char *eol = strchrnul(bol, '\n');
1055                 int len = (eol - bol) + !!*eol;
1056
1057                 if (!copypos) {
1058                         strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1059                         inspos += gpg_sig_header_len;
1060                 }
1061                 strbuf_insert(buf, inspos++, " ", 1);
1062                 strbuf_insert(buf, inspos, bol, len);
1063                 inspos += len;
1064                 copypos += len;
1065         }
1066         strbuf_release(&sig);
1067         return 0;
1068 }
1069
1070 int parse_signed_commit(const unsigned char *sha1,
1071                         struct strbuf *payload, struct strbuf *signature)
1072 {
1073         unsigned long size;
1074         enum object_type type;
1075         char *buffer = read_sha1_file(sha1, &type, &size);
1076         int in_signature, saw_signature = -1;
1077         char *line, *tail;
1078
1079         if (!buffer || type != OBJ_COMMIT)
1080                 goto cleanup;
1081
1082         line = buffer;
1083         tail = buffer + size;
1084         in_signature = 0;
1085         saw_signature = 0;
1086         while (line < tail) {
1087                 const char *sig = NULL;
1088                 char *next = memchr(line, '\n', tail - line);
1089
1090                 next = next ? next + 1 : tail;
1091                 if (in_signature && line[0] == ' ')
1092                         sig = line + 1;
1093                 else if (!prefixcmp(line, gpg_sig_header) &&
1094                          line[gpg_sig_header_len] == ' ')
1095                         sig = line + gpg_sig_header_len + 1;
1096                 if (sig) {
1097                         strbuf_add(signature, sig, next - sig);
1098                         saw_signature = 1;
1099                         in_signature = 1;
1100                 } else {
1101                         if (*line == '\n')
1102                                 /* dump the whole remainder of the buffer */
1103                                 next = tail;
1104                         strbuf_add(payload, line, next - line);
1105                         in_signature = 0;
1106                 }
1107                 line = next;
1108         }
1109  cleanup:
1110         free(buffer);
1111         return saw_signature;
1112 }
1113
1114 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1115 {
1116         struct merge_remote_desc *desc;
1117         struct commit_extra_header *mergetag;
1118         char *buf;
1119         unsigned long size, len;
1120         enum object_type type;
1121
1122         desc = merge_remote_util(parent);
1123         if (!desc || !desc->obj)
1124                 return;
1125         buf = read_sha1_file(desc->obj->sha1, &type, &size);
1126         if (!buf || type != OBJ_TAG)
1127                 goto free_return;
1128         len = parse_signature(buf, size);
1129         if (size == len)
1130                 goto free_return;
1131         /*
1132          * We could verify this signature and either omit the tag when
1133          * it does not validate, but the integrator may not have the
1134          * public key of the signer of the tag he is merging, while a
1135          * later auditor may have it while auditing, so let's not run
1136          * verify-signed-buffer here for now...
1137          *
1138          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1139          *      warn("warning: signed tag unverified.");
1140          */
1141         mergetag = xcalloc(1, sizeof(*mergetag));
1142         mergetag->key = xstrdup("mergetag");
1143         mergetag->value = buf;
1144         mergetag->len = size;
1145
1146         **tail = mergetag;
1147         *tail = &mergetag->next;
1148         return;
1149
1150 free_return:
1151         free(buf);
1152 }
1153
1154 static struct {
1155         char result;
1156         const char *check;
1157 } sigcheck_gpg_status[] = {
1158         { 'G', "\n[GNUPG:] GOODSIG " },
1159         { 'B', "\n[GNUPG:] BADSIG " },
1160         { 'U', "\n[GNUPG:] TRUST_NEVER" },
1161         { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1162 };
1163
1164 static void parse_gpg_output(struct signature_check *sigc)
1165 {
1166         const char *buf = sigc->gpg_status;
1167         int i;
1168
1169         /* Iterate over all search strings */
1170         for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1171                 const char *found, *next;
1172
1173                 if (!prefixcmp(buf, sigcheck_gpg_status[i].check + 1)) {
1174                         /* At the very beginning of the buffer */
1175                         found = buf + strlen(sigcheck_gpg_status[i].check + 1);
1176                 } else {
1177                         found = strstr(buf, sigcheck_gpg_status[i].check);
1178                         if (!found)
1179                                 continue;
1180                         found += strlen(sigcheck_gpg_status[i].check);
1181                 }
1182                 sigc->result = sigcheck_gpg_status[i].result;
1183                 /* The trust messages are not followed by key/signer information */
1184                 if (sigc->result != 'U') {
1185                         sigc->key = xmemdupz(found, 16);
1186                         found += 17;
1187                         next = strchrnul(found, '\n');
1188                         sigc->signer = xmemdupz(found, next - found);
1189                 }
1190         }
1191 }
1192
1193 void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1194 {
1195         struct strbuf payload = STRBUF_INIT;
1196         struct strbuf signature = STRBUF_INIT;
1197         struct strbuf gpg_output = STRBUF_INIT;
1198         struct strbuf gpg_status = STRBUF_INIT;
1199         int status;
1200
1201         sigc->result = 'N';
1202
1203         if (parse_signed_commit(commit->object.sha1,
1204                                 &payload, &signature) <= 0)
1205                 goto out;
1206         status = verify_signed_buffer(payload.buf, payload.len,
1207                                       signature.buf, signature.len,
1208                                       &gpg_output, &gpg_status);
1209         if (status && !gpg_output.len)
1210                 goto out;
1211         sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1212         sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1213         parse_gpg_output(sigc);
1214
1215  out:
1216         strbuf_release(&gpg_status);
1217         strbuf_release(&gpg_output);
1218         strbuf_release(&payload);
1219         strbuf_release(&signature);
1220 }
1221
1222
1223
1224 void append_merge_tag_headers(struct commit_list *parents,
1225                               struct commit_extra_header ***tail)
1226 {
1227         while (parents) {
1228                 struct commit *parent = parents->item;
1229                 handle_signed_tag(parent, tail);
1230                 parents = parents->next;
1231         }
1232 }
1233
1234 static void add_extra_header(struct strbuf *buffer,
1235                              struct commit_extra_header *extra)
1236 {
1237         strbuf_addstr(buffer, extra->key);
1238         if (extra->len)
1239                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
1240         else
1241                 strbuf_addch(buffer, '\n');
1242 }
1243
1244 struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1245                                                       const char **exclude)
1246 {
1247         struct commit_extra_header *extra = NULL;
1248         unsigned long size;
1249         enum object_type type;
1250         char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1251         if (buffer && type == OBJ_COMMIT)
1252                 extra = read_commit_extra_header_lines(buffer, size, exclude);
1253         free(buffer);
1254         return extra;
1255 }
1256
1257 static inline int standard_header_field(const char *field, size_t len)
1258 {
1259         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1260                 (len == 6 && !memcmp(field, "parent ", 7)) ||
1261                 (len == 6 && !memcmp(field, "author ", 7)) ||
1262                 (len == 9 && !memcmp(field, "committer ", 10)) ||
1263                 (len == 8 && !memcmp(field, "encoding ", 9)));
1264 }
1265
1266 static int excluded_header_field(const char *field, size_t len, const char **exclude)
1267 {
1268         if (!exclude)
1269                 return 0;
1270
1271         while (*exclude) {
1272                 size_t xlen = strlen(*exclude);
1273                 if (len == xlen &&
1274                     !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1275                         return 1;
1276                 exclude++;
1277         }
1278         return 0;
1279 }
1280
1281 static struct commit_extra_header *read_commit_extra_header_lines(
1282         const char *buffer, size_t size,
1283         const char **exclude)
1284 {
1285         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1286         const char *line, *next, *eof, *eob;
1287         struct strbuf buf = STRBUF_INIT;
1288
1289         for (line = buffer, eob = line + size;
1290              line < eob && *line != '\n';
1291              line = next) {
1292                 next = memchr(line, '\n', eob - line);
1293                 next = next ? next + 1 : eob;
1294                 if (*line == ' ') {
1295                         /* continuation */
1296                         if (it)
1297                                 strbuf_add(&buf, line + 1, next - (line + 1));
1298                         continue;
1299                 }
1300                 if (it)
1301                         it->value = strbuf_detach(&buf, &it->len);
1302                 strbuf_reset(&buf);
1303                 it = NULL;
1304
1305                 eof = strchr(line, ' ');
1306                 if (next <= eof)
1307                         eof = next;
1308
1309                 if (standard_header_field(line, eof - line) ||
1310                     excluded_header_field(line, eof - line, exclude))
1311                         continue;
1312
1313                 it = xcalloc(1, sizeof(*it));
1314                 it->key = xmemdupz(line, eof-line);
1315                 *tail = it;
1316                 tail = &it->next;
1317                 if (eof + 1 < next)
1318                         strbuf_add(&buf, eof + 1, next - (eof + 1));
1319         }
1320         if (it)
1321                 it->value = strbuf_detach(&buf, &it->len);
1322         return extra;
1323 }
1324
1325 void free_commit_extra_headers(struct commit_extra_header *extra)
1326 {
1327         while (extra) {
1328                 struct commit_extra_header *next = extra->next;
1329                 free(extra->key);
1330                 free(extra->value);
1331                 free(extra);
1332                 extra = next;
1333         }
1334 }
1335
1336 int commit_tree(const struct strbuf *msg, unsigned char *tree,
1337                 struct commit_list *parents, unsigned char *ret,
1338                 const char *author, const char *sign_commit)
1339 {
1340         struct commit_extra_header *extra = NULL, **tail = &extra;
1341         int result;
1342
1343         append_merge_tag_headers(parents, &tail);
1344         result = commit_tree_extended(msg, tree, parents, ret,
1345                                       author, sign_commit, extra);
1346         free_commit_extra_headers(extra);
1347         return result;
1348 }
1349
1350 static int find_invalid_utf8(const char *buf, int len)
1351 {
1352         int offset = 0;
1353         static const unsigned int max_codepoint[] = {
1354                 0x7f, 0x7ff, 0xffff, 0x10ffff
1355         };
1356
1357         while (len) {
1358                 unsigned char c = *buf++;
1359                 int bytes, bad_offset;
1360                 unsigned int codepoint;
1361                 unsigned int min_val, max_val;
1362
1363                 len--;
1364                 offset++;
1365
1366                 /* Simple US-ASCII? No worries. */
1367                 if (c < 0x80)
1368                         continue;
1369
1370                 bad_offset = offset-1;
1371
1372                 /*
1373                  * Count how many more high bits set: that's how
1374                  * many more bytes this sequence should have.
1375                  */
1376                 bytes = 0;
1377                 while (c & 0x40) {
1378                         c <<= 1;
1379                         bytes++;
1380                 }
1381
1382                 /*
1383                  * Must be between 1 and 3 more bytes.  Longer sequences result in
1384                  * codepoints beyond U+10FFFF, which are guaranteed never to exist.
1385                  */
1386                 if (bytes < 1 || 3 < bytes)
1387                         return bad_offset;
1388
1389                 /* Do we *have* that many bytes? */
1390                 if (len < bytes)
1391                         return bad_offset;
1392
1393                 /*
1394                  * Place the encoded bits at the bottom of the value and compute the
1395                  * valid range.
1396                  */
1397                 codepoint = (c & 0x7f) >> bytes;
1398                 min_val = max_codepoint[bytes-1] + 1;
1399                 max_val = max_codepoint[bytes];
1400
1401                 offset += bytes;
1402                 len -= bytes;
1403
1404                 /* And verify that they are good continuation bytes */
1405                 do {
1406                         codepoint <<= 6;
1407                         codepoint |= *buf & 0x3f;
1408                         if ((*buf++ & 0xc0) != 0x80)
1409                                 return bad_offset;
1410                 } while (--bytes);
1411
1412                 /* Reject codepoints that are out of range for the sequence length. */
1413                 if (codepoint < min_val || codepoint > max_val)
1414                         return bad_offset;
1415                 /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
1416                 if ((codepoint & 0x1ff800) == 0xd800)
1417                         return bad_offset;
1418                 /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
1419                 if ((codepoint & 0xfffe) == 0xfffe)
1420                         return bad_offset;
1421                 /* So are anything in the range U+FDD0..U+FDEF. */
1422                 if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
1423                         return bad_offset;
1424         }
1425         return -1;
1426 }
1427
1428 /*
1429  * This verifies that the buffer is in proper utf8 format.
1430  *
1431  * If it isn't, it assumes any non-utf8 characters are Latin1,
1432  * and does the conversion.
1433  */
1434 static int verify_utf8(struct strbuf *buf)
1435 {
1436         int ok = 1;
1437         long pos = 0;
1438
1439         for (;;) {
1440                 int bad;
1441                 unsigned char c;
1442                 unsigned char replace[2];
1443
1444                 bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1445                 if (bad < 0)
1446                         return ok;
1447                 pos += bad;
1448                 ok = 0;
1449                 c = buf->buf[pos];
1450                 strbuf_remove(buf, pos, 1);
1451
1452                 /* We know 'c' must be in the range 128-255 */
1453                 replace[0] = 0xc0 + (c >> 6);
1454                 replace[1] = 0x80 + (c & 0x3f);
1455                 strbuf_insert(buf, pos, replace, 2);
1456                 pos += 2;
1457         }
1458 }
1459
1460 static const char commit_utf8_warn[] =
1461 "Warning: commit message did not conform to UTF-8.\n"
1462 "You may want to amend it after fixing the message, or set the config\n"
1463 "variable i18n.commitencoding to the encoding your project uses.\n";
1464
1465 int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1466                          struct commit_list *parents, unsigned char *ret,
1467                          const char *author, const char *sign_commit,
1468                          struct commit_extra_header *extra)
1469 {
1470         int result;
1471         int encoding_is_utf8;
1472         struct strbuf buffer;
1473
1474         assert_sha1_type(tree, OBJ_TREE);
1475
1476         if (memchr(msg->buf, '\0', msg->len))
1477                 return error("a NUL byte in commit log message not allowed.");
1478
1479         /* Not having i18n.commitencoding is the same as having utf-8 */
1480         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1481
1482         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1483         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1484
1485         /*
1486          * NOTE! This ordering means that the same exact tree merged with a
1487          * different order of parents will be a _different_ changeset even
1488          * if everything else stays the same.
1489          */
1490         while (parents) {
1491                 struct commit_list *next = parents->next;
1492                 struct commit *parent = parents->item;
1493
1494                 strbuf_addf(&buffer, "parent %s\n",
1495                             sha1_to_hex(parent->object.sha1));
1496                 free(parents);
1497                 parents = next;
1498         }
1499
1500         /* Person/date information */
1501         if (!author)
1502                 author = git_author_info(IDENT_STRICT);
1503         strbuf_addf(&buffer, "author %s\n", author);
1504         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1505         if (!encoding_is_utf8)
1506                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1507
1508         while (extra) {
1509                 add_extra_header(&buffer, extra);
1510                 extra = extra->next;
1511         }
1512         strbuf_addch(&buffer, '\n');
1513
1514         /* And add the comment */
1515         strbuf_addbuf(&buffer, msg);
1516
1517         /* And check the encoding */
1518         if (encoding_is_utf8 && !verify_utf8(&buffer))
1519                 fprintf(stderr, commit_utf8_warn);
1520
1521         if (sign_commit && do_sign_commit(&buffer, sign_commit))
1522                 return -1;
1523
1524         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1525         strbuf_release(&buffer);
1526         return result;
1527 }
1528
1529 struct commit *get_merge_parent(const char *name)
1530 {
1531         struct object *obj;
1532         struct commit *commit;
1533         unsigned char sha1[20];
1534         if (get_sha1(name, sha1))
1535                 return NULL;
1536         obj = parse_object(sha1);
1537         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1538         if (commit && !commit->util) {
1539                 struct merge_remote_desc *desc;
1540                 desc = xmalloc(sizeof(*desc));
1541                 desc->obj = obj;
1542                 desc->name = strdup(name);
1543                 commit->util = desc;
1544         }
1545         return commit;
1546 }
1547
1548 /*
1549  * Append a commit to the end of the commit_list.
1550  *
1551  * next starts by pointing to the variable that holds the head of an
1552  * empty commit_list, and is updated to point to the "next" field of
1553  * the last item on the list as new commits are appended.
1554  *
1555  * Usage example:
1556  *
1557  *     struct commit_list *list;
1558  *     struct commit_list **next = &list;
1559  *
1560  *     next = commit_list_append(c1, next);
1561  *     next = commit_list_append(c2, next);
1562  *     assert(commit_list_count(list) == 2);
1563  *     return list;
1564  */
1565 struct commit_list **commit_list_append(struct commit *commit,
1566                                         struct commit_list **next)
1567 {
1568         struct commit_list *new = xmalloc(sizeof(struct commit_list));
1569         new->item = commit;
1570         *next = new;
1571         new->next = NULL;
1572         return &new->next;
1573 }
1574
1575 void print_commit_list(struct commit_list *list,
1576                        const char *format_cur,
1577                        const char *format_last)
1578 {
1579         for ( ; list; list = list->next) {
1580                 const char *format = list->next ? format_cur : format_last;
1581                 printf(format, sha1_to_hex(list->item->object.sha1));
1582         }
1583 }