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 #include "sha1-lookup.h"
  14
  15 static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  16
  17 int save_commit_buffer = 1;
  18
  19 const char *commit_type = "commit";
  20 static int commit_count;
  21
  22 static struct commit *check_commit(struct object *obj,
  23                                    const unsigned char *sha1,
  24                                    int quiet)
  25 {
  26         if (obj->type != OBJ_COMMIT) {
  27                 if (!quiet)
  28                         error("Object %s is a %s, not a commit",
  29                               sha1_to_hex(sha1), typename(obj->type));
  30                 return NULL;
  31         }
  32         return (struct commit *) obj;
  33 }
  34
  35 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  36                                               int quiet)
  37 {
  38         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  39
  40         if (!obj)
  41                 return NULL;
  42         return check_commit(obj, sha1, quiet);
  43 }
  44
  45 struct commit *lookup_commit_reference(const unsigned char *sha1)
  46 {
  47         return lookup_commit_reference_gently(sha1, 0);
  48 }
  49
  50 struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  51 {
  52         struct commit *c = lookup_commit_reference(sha1);
  53         if (!c)
  54                 die(_("could not parse %s"), ref_name);
  55         if (hashcmp(sha1, c->object.sha1)) {
  56                 warning(_("%s %s is not a commit!"),
  57                         ref_name, sha1_to_hex(sha1));
  58         }
  59         return c;
  60 }
  61
  62 struct commit *lookup_commit(const unsigned char *sha1)
  63 {
  64         struct object *obj = lookup_object(sha1);
  65         if (!obj) {
  66                 struct commit *c = alloc_commit_node();
  67                 c->index = commit_count++;
  68                 return create_object(sha1, OBJ_COMMIT, c);
  69         }
  70         if (!obj->type)
  71                 obj->type = OBJ_COMMIT;
  72         return check_commit(obj, sha1, 0);
  73 }
  74
  75 struct commit *lookup_commit_reference_by_name(const char *name)
  76 {
  77         unsigned char sha1[20];
  78         struct commit *commit;
  79
  80         if (get_sha1_committish(name, sha1))
  81                 return NULL;
  82         commit = lookup_commit_reference(sha1);
  83         if (parse_commit(commit))
  84                 return NULL;
  85         return commit;
  86 }
  87
  88 static unsigned long parse_commit_date(const char *buf, const char *tail)
  89 {
  90         const char *dateptr;
  91
  92         if (buf + 6 >= tail)
  93                 return 0;
  94         if (memcmp(buf, "author", 6))
  95                 return 0;
  96         while (buf < tail && *buf++ != '\n')
  97                 /* nada */;
  98         if (buf + 9 >= tail)
  99                 return 0;
 100         if (memcmp(buf, "committer", 9))
 101                 return 0;
 102         while (buf < tail && *buf++ != '>')
 103                 /* nada */;
 104         if (buf >= tail)
 105                 return 0;
 106         dateptr = buf;
 107         while (buf < tail && *buf++ != '\n')
 108                 /* nada */;
 109         if (buf >= tail)
 110                 return 0;
 111         /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 112         return strtoul(dateptr, NULL, 10);
 113 }
 114
 115 static struct commit_graft **commit_graft;
 116 static int commit_graft_alloc, commit_graft_nr;
 117
 118 static const unsigned char *commit_graft_sha1_access(size_t index, void *table)
 119 {
 120         struct commit_graft **commit_graft_table = table;
 121         return commit_graft_table[index]->sha1;
 122 }
 123
 124 static int commit_graft_pos(const unsigned char *sha1)
 125 {
 126         return sha1_pos(sha1, commit_graft, commit_graft_nr,
 127                         commit_graft_sha1_access);
 128 }
 129
 130 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 131 {
 132         int pos = commit_graft_pos(graft->sha1);
 133
 134         if (0 <= pos) {
 135                 if (ignore_dups)
 136                         free(graft);
 137                 else {
 138                         free(commit_graft[pos]);
 139                         commit_graft[pos] = graft;
 140                 }
 141                 return 1;
 142         }
 143         pos = -pos - 1;
 144         if (commit_graft_alloc <= ++commit_graft_nr) {
 145                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 146                 commit_graft = xrealloc(commit_graft,
 147                                         sizeof(*commit_graft) *
 148                                         commit_graft_alloc);
 149         }
 150         if (pos < commit_graft_nr)
 151                 memmove(commit_graft + pos + 1,
 152                         commit_graft + pos,
 153                         (commit_graft_nr - pos - 1) *
 154                         sizeof(*commit_graft));
 155         commit_graft[pos] = graft;
 156         return 0;
 157 }
 158
 159 struct commit_graft *read_graft_line(char *buf, int len)
 160 {
 161         /* The format is just "Commit Parent1 Parent2 ...\n" */
 162         int i;
 163         struct commit_graft *graft = NULL;
 164
 165         while (len && isspace(buf[len-1]))
 166                 buf[--len] = '\0';
 167         if (buf[0] == '#' || buf[0] == '\0')
 168                 return NULL;
 169         if ((len + 1) % 41)
 170                 goto bad_graft_data;
 171         i = (len + 1) / 41 - 1;
 172         graft = xmalloc(sizeof(*graft) + 20 * i);
 173         graft->nr_parent = i;
 174         if (get_sha1_hex(buf, graft->sha1))
 175                 goto bad_graft_data;
 176         for (i = 40; i < len; i += 41) {
 177                 if (buf[i] != ' ')
 178                         goto bad_graft_data;
 179                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 180                         goto bad_graft_data;
 181         }
 182         return graft;
 183
 184 bad_graft_data:
 185         error("bad graft data: %s", buf);
 186         free(graft);
 187         return NULL;
 188 }
 189
 190 static int read_graft_file(const char *graft_file)
 191 {
 192         FILE *fp = fopen(graft_file, "r");
 193         struct strbuf buf = STRBUF_INIT;
 194         if (!fp)
 195                 return -1;
 196         while (!strbuf_getwholeline(&buf, fp, '\n')) {
 197                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 198                 struct commit_graft *graft = read_graft_line(buf.buf, buf.len);
 199                 if (!graft)
 200                         continue;
 201                 if (register_commit_graft(graft, 1))
 202                         error("duplicate graft data: %s", buf.buf);
 203         }
 204         fclose(fp);
 205         strbuf_release(&buf);
 206         return 0;
 207 }
 208
 209 static void prepare_commit_graft(void)
 210 {
 211         static int commit_graft_prepared;
 212         char *graft_file;
 213
 214         if (commit_graft_prepared)
 215                 return;
 216         graft_file = get_graft_file();
 217         read_graft_file(graft_file);
 218         /* make sure shallows are read */
 219         is_repository_shallow();
 220         commit_graft_prepared = 1;
 221 }
 222
 223 struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 224 {
 225         int pos;
 226         prepare_commit_graft();
 227         pos = commit_graft_pos(sha1);
 228         if (pos < 0)
 229                 return NULL;
 230         return commit_graft[pos];
 231 }
 232
 233 int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 234 {
 235         int i, ret;
 236         for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 237                 ret = fn(commit_graft[i], cb_data);
 238         return ret;
 239 }
 240
 241 int unregister_shallow(const unsigned char *sha1)
 242 {
 243         int pos = commit_graft_pos(sha1);
 244         if (pos < 0)
 245                 return -1;
 246         if (pos + 1 < commit_graft_nr)
 247                 memmove(commit_graft + pos, commit_graft + pos + 1,
 248                                 sizeof(struct commit_graft *)
 249                                 * (commit_graft_nr - pos - 1));
 250         commit_graft_nr--;
 251         return 0;
 252 }
 253
 254 int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 255 {
 256         const char *tail = buffer;
 257         const char *bufptr = buffer;
 258         unsigned char parent[20];
 259         struct commit_list **pptr;
 260         struct commit_graft *graft;
 261
 262         if (item->object.parsed)
 263                 return 0;
 264         item->object.parsed = 1;
 265         tail += size;
 266         if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 267                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 268         if (get_sha1_hex(bufptr + 5, parent) < 0)
 269                 return error("bad tree pointer in commit %s",
 270                              sha1_to_hex(item->object.sha1));
 271         item->tree = lookup_tree(parent);
 272         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 273         pptr = &item->parents;
 274
 275         graft = lookup_commit_graft(item->object.sha1);
 276         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 277                 struct commit *new_parent;
 278
 279                 if (tail <= bufptr + 48 ||
 280                     get_sha1_hex(bufptr + 7, parent) ||
 281                     bufptr[47] != '\n')
 282                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 283                 bufptr += 48;
 284                 /*
 285                  * The clone is shallow if nr_parent < 0, and we must
 286                  * not traverse its real parents even when we unhide them.
 287                  */
 288                 if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 289                         continue;
 290                 new_parent = lookup_commit(parent);
 291                 if (new_parent)
 292                         pptr = &commit_list_insert(new_parent, pptr)->next;
 293         }
 294         if (graft) {
 295                 int i;
 296                 struct commit *new_parent;
 297                 for (i = 0; i < graft->nr_parent; i++) {
 298                         new_parent = lookup_commit(graft->parent[i]);
 299                         if (!new_parent)
 300                                 continue;
 301                         pptr = &commit_list_insert(new_parent, pptr)->next;
 302                 }
 303         }
 304         item->date = parse_commit_date(bufptr, tail);
 305
 306         return 0;
 307 }
 308
 309 int parse_commit(struct commit *item)
 310 {
 311         enum object_type type;
 312         void *buffer;
 313         unsigned long size;
 314         int ret;
 315
 316         if (!item)
 317                 return -1;
 318         if (item->object.parsed)
 319                 return 0;
 320         buffer = read_sha1_file(item->object.sha1, &type, &size);
 321         if (!buffer)
 322                 return error("Could not read %s",
 323                              sha1_to_hex(item->object.sha1));
 324         if (type != OBJ_COMMIT) {
 325                 free(buffer);
 326                 return error("Object %s not a commit",
 327                              sha1_to_hex(item->object.sha1));
 328         }
 329         ret = parse_commit_buffer(item, buffer, size);
 330         if (save_commit_buffer && !ret) {
 331                 item->buffer = buffer;
 332                 return 0;
 333         }
 334         free(buffer);
 335         return ret;
 336 }
 337
 338 void parse_commit_or_die(struct commit *item)
 339 {
 340         if (parse_commit(item))
 341                 die("unable to parse commit %s",
 342                     item ? sha1_to_hex(item->object.sha1) : "(null)");
 343 }
 344
 345 int find_commit_subject(const char *commit_buffer, const char **subject)
 346 {
 347         const char *eol;
 348         const char *p = commit_buffer;
 349
 350         while (*p && (*p != '\n' || p[1] != '\n'))
 351                 p++;
 352         if (*p) {
 353                 p += 2;
 354                 for (eol = p; *eol && *eol != '\n'; eol++)
 355                         ; /* do nothing */
 356         } else
 357                 eol = p;
 358
 359         *subject = p;
 360
 361         return eol - p;
 362 }
 363
 364 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 365 {
 366         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 367         new_list->item = item;
 368         new_list->next = *list_p;
 369         *list_p = new_list;
 370         return new_list;
 371 }
 372
 373 unsigned commit_list_count(const struct commit_list *l)
 374 {
 375         unsigned c = 0;
 376         for (; l; l = l->next )
 377                 c++;
 378         return c;
 379 }
 380
 381 struct commit_list *copy_commit_list(struct commit_list *list)
 382 {
 383         struct commit_list *head = NULL;
 384         struct commit_list **pp = &head;
 385         while (list) {
 386                 struct commit_list *new;
 387                 new = xmalloc(sizeof(struct commit_list));
 388                 new->item = list->item;
 389                 new->next = NULL;
 390                 *pp = new;
 391                 pp = &new->next;
 392                 list = list->next;
 393         }
 394         return head;
 395 }
 396
 397 void free_commit_list(struct commit_list *list)
 398 {
 399         while (list) {
 400                 struct commit_list *temp = list;
 401                 list = temp->next;
 402                 free(temp);
 403         }
 404 }
 405
 406 struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 407 {
 408         struct commit_list **pp = list;
 409         struct commit_list *p;
 410         while ((p = *pp) != NULL) {
 411                 if (p->item->date < item->date) {
 412                         break;
 413                 }
 414                 pp = &p->next;
 415         }
 416         return commit_list_insert(item, pp);
 417 }
 418
 419 static int commit_list_compare_by_date(const void *a, const void *b)
 420 {
 421         unsigned long a_date = ((const struct commit_list *)a)->item->date;
 422         unsigned long b_date = ((const struct commit_list *)b)->item->date;
 423         if (a_date < b_date)
 424                 return 1;
 425         if (a_date > b_date)
 426                 return -1;
 427         return 0;
 428 }
 429
 430 static void *commit_list_get_next(const void *a)
 431 {
 432         return ((const struct commit_list *)a)->next;
 433 }
 434
 435 static void commit_list_set_next(void *a, void *next)
 436 {
 437         ((struct commit_list *)a)->next = next;
 438 }
 439
 440 void commit_list_sort_by_date(struct commit_list **list)
 441 {
 442         *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 443                                 commit_list_compare_by_date);
 444 }
 445
 446 struct commit *pop_most_recent_commit(struct commit_list **list,
 447                                       unsigned int mark)
 448 {
 449         struct commit *ret = (*list)->item;
 450         struct commit_list *parents = ret->parents;
 451         struct commit_list *old = *list;
 452
 453         *list = (*list)->next;
 454         free(old);
 455
 456         while (parents) {
 457                 struct commit *commit = parents->item;
 458                 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 459                         commit->object.flags |= mark;
 460                         commit_list_insert_by_date(commit, list);
 461                 }
 462                 parents = parents->next;
 463         }
 464         return ret;
 465 }
 466
 467 static void clear_commit_marks_1(struct commit_list **plist,
 468                                  struct commit *commit, unsigned int mark)
 469 {
 470         while (commit) {
 471                 struct commit_list *parents;
 472
 473                 if (!(mark & commit->object.flags))
 474                         return;
 475
 476                 commit->object.flags &= ~mark;
 477
 478                 parents = commit->parents;
 479                 if (!parents)
 480                         return;
 481
 482                 while ((parents = parents->next))
 483                         commit_list_insert(parents->item, plist);
 484
 485                 commit = commit->parents->item;
 486         }
 487 }
 488
 489 void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 490 {
 491         struct commit_list *list = NULL;
 492
 493         while (nr--) {
 494                 commit_list_insert(*commit, &list);
 495                 commit++;
 496         }
 497         while (list)
 498                 clear_commit_marks_1(&list, pop_commit(&list), mark);
 499 }
 500
 501 void clear_commit_marks(struct commit *commit, unsigned int mark)
 502 {
 503         clear_commit_marks_many(1, &commit, mark);
 504 }
 505
 506 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 507 {
 508         struct object *object;
 509         struct commit *commit;
 510         unsigned int i;
 511
 512         for (i = 0; i < a->nr; i++) {
 513                 object = a->objects[i].item;
 514                 commit = lookup_commit_reference_gently(object->sha1, 1);
 515                 if (commit)
 516                         clear_commit_marks(commit, mark);
 517         }
 518 }
 519
 520 struct commit *pop_commit(struct commit_list **stack)
 521 {
 522         struct commit_list *top = *stack;
 523         struct commit *item = top ? top->item : NULL;
 524
 525         if (top) {
 526                 *stack = top->next;
 527                 free(top);
 528         }
 529         return item;
 530 }
 531
 532 /*
 533  * Topological sort support
 534  */
 535
 536 /* count number of children that have not been emitted */
 537 define_commit_slab(indegree_slab, int);
 538
 539 /* record author-date for each commit object */
 540 define_commit_slab(author_date_slab, unsigned long);
 541
 542 static void record_author_date(struct author_date_slab *author_date,
 543                                struct commit *commit)
 544 {
 545         const char *buf, *line_end;
 546         char *buffer = NULL;
 547         struct ident_split ident;
 548         char *date_end;
 549         unsigned long date;
 550
 551         if (!commit->buffer) {
 552                 unsigned long size;
 553                 enum object_type type;
 554                 buffer = read_sha1_file(commit->object.sha1, &type, &size);
 555                 if (!buffer)
 556                         return;
 557         }
 558
 559         for (buf = commit->buffer ? commit->buffer : buffer;
 560              buf;
 561              buf = line_end + 1) {
 562                 line_end = strchrnul(buf, '\n');
 563                 if (!starts_with(buf, "author ")) {
 564                         if (!line_end[0] || line_end[1] == '\n')
 565                                 return; /* end of header */
 566                         continue;
 567                 }
 568                 if (split_ident_line(&ident,
 569                                      buf + strlen("author "),
 570                                      line_end - (buf + strlen("author "))) ||
 571                     !ident.date_begin || !ident.date_end)
 572                         goto fail_exit; /* malformed "author" line */
 573                 break;
 574         }
 575
 576         date = strtoul(ident.date_begin, &date_end, 10);
 577         if (date_end != ident.date_end)
 578                 goto fail_exit; /* malformed date */
 579         *(author_date_slab_at(author_date, commit)) = date;
 580
 581 fail_exit:
 582         free(buffer);
 583 }
 584
 585 static int compare_commits_by_author_date(const void *a_, const void *b_,
 586                                           void *cb_data)
 587 {
 588         const struct commit *a = a_, *b = b_;
 589         struct author_date_slab *author_date = cb_data;
 590         unsigned long a_date = *(author_date_slab_at(author_date, a));
 591         unsigned long b_date = *(author_date_slab_at(author_date, b));
 592
 593         /* newer commits with larger date first */
 594         if (a_date < b_date)
 595                 return 1;
 596         else if (a_date > b_date)
 597                 return -1;
 598         return 0;
 599 }
 600
 601 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 602 {
 603         const struct commit *a = a_, *b = b_;
 604         /* newer commits with larger date first */
 605         if (a->date < b->date)
 606                 return 1;
 607         else if (a->date > b->date)
 608                 return -1;
 609         return 0;
 610 }
 611
 612 /*
 613  * Performs an in-place topological sort on the list supplied.
 614  */
 615 void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 616 {
 617         struct commit_list *next, *orig = *list;
 618         struct commit_list **pptr;
 619         struct indegree_slab indegree;
 620         struct prio_queue queue;
 621         struct commit *commit;
 622         struct author_date_slab author_date;
 623
 624         if (!orig)
 625                 return;
 626         *list = NULL;
 627
 628         init_indegree_slab(&indegree);
 629         memset(&queue, '\0', sizeof(queue));
 630
 631         switch (sort_order) {
 632         default: /* REV_SORT_IN_GRAPH_ORDER */
 633                 queue.compare = NULL;
 634                 break;
 635         case REV_SORT_BY_COMMIT_DATE:
 636                 queue.compare = compare_commits_by_commit_date;
 637                 break;
 638         case REV_SORT_BY_AUTHOR_DATE:
 639                 init_author_date_slab(&author_date);
 640                 queue.compare = compare_commits_by_author_date;
 641                 queue.cb_data = &author_date;
 642                 break;
 643         }
 644
 645         /* Mark them and clear the indegree */
 646         for (next = orig; next; next = next->next) {
 647                 struct commit *commit = next->item;
 648                 *(indegree_slab_at(&indegree, commit)) = 1;
 649                 /* also record the author dates, if needed */
 650                 if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 651                         record_author_date(&author_date, commit);
 652         }
 653
 654         /* update the indegree */
 655         for (next = orig; next; next = next->next) {
 656                 struct commit_list *parents = next->item->parents;
 657                 while (parents) {
 658                         struct commit *parent = parents->item;
 659                         int *pi = indegree_slab_at(&indegree, parent);
 660
 661                         if (*pi)
 662                                 (*pi)++;
 663                         parents = parents->next;
 664                 }
 665         }
 666
 667         /*
 668          * find the tips
 669          *
 670          * tips are nodes not reachable from any other node in the list
 671          *
 672          * the tips serve as a starting set for the work queue.
 673          */
 674         for (next = orig; next; next = next->next) {
 675                 struct commit *commit = next->item;
 676
 677                 if (*(indegree_slab_at(&indegree, commit)) == 1)
 678                         prio_queue_put(&queue, commit);
 679         }
 680
 681         /*
 682          * This is unfortunate; the initial tips need to be shown
 683          * in the order given from the revision traversal machinery.
 684          */
 685         if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 686                 prio_queue_reverse(&queue);
 687
 688         /* We no longer need the commit list */
 689         free_commit_list(orig);
 690
 691         pptr = list;
 692         *list = NULL;
 693         while ((commit = prio_queue_get(&queue)) != NULL) {
 694                 struct commit_list *parents;
 695
 696                 for (parents = commit->parents; parents ; parents = parents->next) {
 697                         struct commit *parent = parents->item;
 698                         int *pi = indegree_slab_at(&indegree, parent);
 699
 700                         if (!*pi)
 701                                 continue;
 702
 703                         /*
 704                          * parents are only enqueued for emission
 705                          * when all their children have been emitted thereby
 706                          * guaranteeing topological order.
 707                          */
 708                         if (--(*pi) == 1)
 709                                 prio_queue_put(&queue, parent);
 710                 }
 711                 /*
 712                  * all children of commit have already been
 713                  * emitted. we can emit it now.
 714                  */
 715                 *(indegree_slab_at(&indegree, commit)) = 0;
 716
 717                 pptr = &commit_list_insert(commit, pptr)->next;
 718         }
 719
 720         clear_indegree_slab(&indegree);
 721         clear_prio_queue(&queue);
 722         if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 723                 clear_author_date_slab(&author_date);
 724 }
 725
 726 /* merge-base stuff */
 727
 728 /* bits #0..15 in revision.h */
 729 #define PARENT1         (1u<<16)
 730 #define PARENT2         (1u<<17)
 731 #define STALE           (1u<<18)
 732 #define RESULT          (1u<<19)
 733
 734 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 735
 736 static struct commit *interesting(struct commit_list *list)
 737 {
 738         while (list) {
 739                 struct commit *commit = list->item;
 740                 list = list->next;
 741                 if (commit->object.flags & STALE)
 742                         continue;
 743                 return commit;
 744         }
 745         return NULL;
 746 }
 747
 748 /* all input commits in one and twos[] must have been parsed! */
 749 static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 750 {
 751         struct commit_list *list = NULL;
 752         struct commit_list *result = NULL;
 753         int i;
 754
 755         one->object.flags |= PARENT1;
 756         commit_list_insert_by_date(one, &list);
 757         if (!n)
 758                 return list;
 759         for (i = 0; i < n; i++) {
 760                 twos[i]->object.flags |= PARENT2;
 761                 commit_list_insert_by_date(twos[i], &list);
 762         }
 763
 764         while (interesting(list)) {
 765                 struct commit *commit;
 766                 struct commit_list *parents;
 767                 struct commit_list *next;
 768                 int flags;
 769
 770                 commit = list->item;
 771                 next = list->next;
 772                 free(list);
 773                 list = next;
 774
 775                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 776                 if (flags == (PARENT1 | PARENT2)) {
 777                         if (!(commit->object.flags & RESULT)) {
 778                                 commit->object.flags |= RESULT;
 779                                 commit_list_insert_by_date(commit, &result);
 780                         }
 781                         /* Mark parents of a found merge stale */
 782                         flags |= STALE;
 783                 }
 784                 parents = commit->parents;
 785                 while (parents) {
 786                         struct commit *p = parents->item;
 787                         parents = parents->next;
 788                         if ((p->object.flags & flags) == flags)
 789                                 continue;
 790                         if (parse_commit(p))
 791                                 return NULL;
 792                         p->object.flags |= flags;
 793                         commit_list_insert_by_date(p, &list);
 794                 }
 795         }
 796
 797         free_commit_list(list);
 798         return result;
 799 }
 800
 801 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 802 {
 803         struct commit_list *list = NULL;
 804         struct commit_list *result = NULL;
 805         int i;
 806
 807         for (i = 0; i < n; i++) {
 808                 if (one == twos[i])
 809                         /*
 810                          * We do not mark this even with RESULT so we do not
 811                          * have to clean it up.
 812                          */
 813                         return commit_list_insert(one, &result);
 814         }
 815
 816         if (parse_commit(one))
 817                 return NULL;
 818         for (i = 0; i < n; i++) {
 819                 if (parse_commit(twos[i]))
 820                         return NULL;
 821         }
 822
 823         list = paint_down_to_common(one, n, twos);
 824
 825         while (list) {
 826                 struct commit_list *next = list->next;
 827                 if (!(list->item->object.flags & STALE))
 828                         commit_list_insert_by_date(list->item, &result);
 829                 free(list);
 830                 list = next;
 831         }
 832         return result;
 833 }
 834
 835 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 836 {
 837         struct commit_list *i, *j, *k, *ret = NULL;
 838
 839         if (!in)
 840                 return ret;
 841
 842         commit_list_insert(in->item, &ret);
 843
 844         for (i = in->next; i; i = i->next) {
 845                 struct commit_list *new = NULL, *end = NULL;
 846
 847                 for (j = ret; j; j = j->next) {
 848                         struct commit_list *bases;
 849                         bases = get_merge_bases(i->item, j->item, 1);
 850                         if (!new)
 851                                 new = bases;
 852                         else
 853                                 end->next = bases;
 854                         for (k = bases; k; k = k->next)
 855                                 end = k;
 856                 }
 857                 ret = new;
 858         }
 859         return ret;
 860 }
 861
 862 static int remove_redundant(struct commit **array, int cnt)
 863 {
 864         /*
 865          * Some commit in the array may be an ancestor of
 866          * another commit.  Move such commit to the end of
 867          * the array, and return the number of commits that
 868          * are independent from each other.
 869          */
 870         struct commit **work;
 871         unsigned char *redundant;
 872         int *filled_index;
 873         int i, j, filled;
 874
 875         work = xcalloc(cnt, sizeof(*work));
 876         redundant = xcalloc(cnt, 1);
 877         filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 878
 879         for (i = 0; i < cnt; i++)
 880                 parse_commit(array[i]);
 881         for (i = 0; i < cnt; i++) {
 882                 struct commit_list *common;
 883
 884                 if (redundant[i])
 885                         continue;
 886                 for (j = filled = 0; j < cnt; j++) {
 887                         if (i == j || redundant[j])
 888                                 continue;
 889                         filled_index[filled] = j;
 890                         work[filled++] = array[j];
 891                 }
 892                 common = paint_down_to_common(array[i], filled, work);
 893                 if (array[i]->object.flags & PARENT2)
 894                         redundant[i] = 1;
 895                 for (j = 0; j < filled; j++)
 896                         if (work[j]->object.flags & PARENT1)
 897                                 redundant[filled_index[j]] = 1;
 898                 clear_commit_marks(array[i], all_flags);
 899                 for (j = 0; j < filled; j++)
 900                         clear_commit_marks(work[j], all_flags);
 901                 free_commit_list(common);
 902         }
 903
 904         /* Now collect the result */
 905         memcpy(work, array, sizeof(*array) * cnt);
 906         for (i = filled = 0; i < cnt; i++)
 907                 if (!redundant[i])
 908                         array[filled++] = work[i];
 909         for (j = filled, i = 0; i < cnt; i++)
 910                 if (redundant[i])
 911                         array[j++] = work[i];
 912         free(work);
 913         free(redundant);
 914         free(filled_index);
 915         return filled;
 916 }
 917
 918 struct commit_list *get_merge_bases_many(struct commit *one,
 919                                          int n,
 920                                          struct commit **twos,
 921                                          int cleanup)
 922 {
 923         struct commit_list *list;
 924         struct commit **rslt;
 925         struct commit_list *result;
 926         int cnt, i;
 927
 928         result = merge_bases_many(one, n, twos);
 929         for (i = 0; i < n; i++) {
 930                 if (one == twos[i])
 931                         return result;
 932         }
 933         if (!result || !result->next) {
 934                 if (cleanup) {
 935                         clear_commit_marks(one, all_flags);
 936                         clear_commit_marks_many(n, twos, all_flags);
 937                 }
 938                 return result;
 939         }
 940
 941         /* There are more than one */
 942         cnt = 0;
 943         list = result;
 944         while (list) {
 945                 list = list->next;
 946                 cnt++;
 947         }
 948         rslt = xcalloc(cnt, sizeof(*rslt));
 949         for (list = result, i = 0; list; list = list->next)
 950                 rslt[i++] = list->item;
 951         free_commit_list(result);
 952
 953         clear_commit_marks(one, all_flags);
 954         clear_commit_marks_many(n, twos, all_flags);
 955
 956         cnt = remove_redundant(rslt, cnt);
 957         result = NULL;
 958         for (i = 0; i < cnt; i++)
 959                 commit_list_insert_by_date(rslt[i], &result);
 960         free(rslt);
 961         return result;
 962 }
 963
 964 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 965                                     int cleanup)
 966 {
 967         return get_merge_bases_many(one, 1, &two, cleanup);
 968 }
 969
 970 /*
 971  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 972  */
 973 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 974 {
 975         if (!with_commit)
 976                 return 1;
 977         while (with_commit) {
 978                 struct commit *other;
 979
 980                 other = with_commit->item;
 981                 with_commit = with_commit->next;
 982                 if (in_merge_bases(other, commit))
 983                         return 1;
 984         }
 985         return 0;
 986 }
 987
 988 /*
 989  * Is "commit" an ancestor of one of the "references"?
 990  */
 991 int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 992 {
 993         struct commit_list *bases;
 994         int ret = 0, i;
 995
 996         if (parse_commit(commit))
 997                 return ret;
 998         for (i = 0; i < nr_reference; i++)
 999                 if (parse_commit(reference[i]))
1000                         return ret;
1001
1002         bases = paint_down_to_common(commit, nr_reference, reference);
1003         if (commit->object.flags & PARENT2)
1004                 ret = 1;
1005         clear_commit_marks(commit, all_flags);
1006         clear_commit_marks_many(nr_reference, reference, all_flags);
1007         free_commit_list(bases);
1008         return ret;
1009 }
1010
1011 /*
1012  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
1013  */
1014 int in_merge_bases(struct commit *commit, struct commit *reference)
1015 {
1016         return in_merge_bases_many(commit, 1, &reference);
1017 }
1018
1019 struct commit_list *reduce_heads(struct commit_list *heads)
1020 {
1021         struct commit_list *p;
1022         struct commit_list *result = NULL, **tail = &result;
1023         struct commit **array;
1024         int num_head, i;
1025
1026         if (!heads)
1027                 return NULL;
1028
1029         /* Uniquify */
1030         for (p = heads; p; p = p->next)
1031                 p->item->object.flags &= ~STALE;
1032         for (p = heads, num_head = 0; p; p = p->next) {
1033                 if (p->item->object.flags & STALE)
1034                         continue;
1035                 p->item->object.flags |= STALE;
1036                 num_head++;
1037         }
1038         array = xcalloc(sizeof(*array), num_head);
1039         for (p = heads, i = 0; p; p = p->next) {
1040                 if (p->item->object.flags & STALE) {
1041                         array[i++] = p->item;
1042                         p->item->object.flags &= ~STALE;
1043                 }
1044         }
1045         num_head = remove_redundant(array, num_head);
1046         for (i = 0; i < num_head; i++)
1047                 tail = &commit_list_insert(array[i], tail)->next;
1048         return result;
1049 }
1050
1051 static const char gpg_sig_header[] = "gpgsig";
1052 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1053
1054 static int do_sign_commit(struct strbuf *buf, const char *keyid)
1055 {
1056         struct strbuf sig = STRBUF_INIT;
1057         int inspos, copypos;
1058
1059         /* find the end of the header */
1060         inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1061
1062         if (!keyid || !*keyid)
1063                 keyid = get_signing_key();
1064         if (sign_buffer(buf, &sig, keyid)) {
1065                 strbuf_release(&sig);
1066                 return -1;
1067         }
1068
1069         for (copypos = 0; sig.buf[copypos]; ) {
1070                 const char *bol = sig.buf + copypos;
1071                 const char *eol = strchrnul(bol, '\n');
1072                 int len = (eol - bol) + !!*eol;
1073
1074                 if (!copypos) {
1075                         strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1076                         inspos += gpg_sig_header_len;
1077                 }
1078                 strbuf_insert(buf, inspos++, " ", 1);
1079                 strbuf_insert(buf, inspos, bol, len);
1080                 inspos += len;
1081                 copypos += len;
1082         }
1083         strbuf_release(&sig);
1084         return 0;
1085 }
1086
1087 int parse_signed_commit(const unsigned char *sha1,
1088                         struct strbuf *payload, struct strbuf *signature)
1089 {
1090         unsigned long size;
1091         enum object_type type;
1092         char *buffer = read_sha1_file(sha1, &type, &size);
1093         int in_signature, saw_signature = -1;
1094         char *line, *tail;
1095
1096         if (!buffer || type != OBJ_COMMIT)
1097                 goto cleanup;
1098
1099         line = buffer;
1100         tail = buffer + size;
1101         in_signature = 0;
1102         saw_signature = 0;
1103         while (line < tail) {
1104                 const char *sig = NULL;
1105                 char *next = memchr(line, '\n', tail - line);
1106
1107                 next = next ? next + 1 : tail;
1108                 if (in_signature && line[0] == ' ')
1109                         sig = line + 1;
1110                 else if (starts_with(line, gpg_sig_header) &&
1111                          line[gpg_sig_header_len] == ' ')
1112                         sig = line + gpg_sig_header_len + 1;
1113                 if (sig) {
1114                         strbuf_add(signature, sig, next - sig);
1115                         saw_signature = 1;
1116                         in_signature = 1;
1117                 } else {
1118                         if (*line == '\n')
1119                                 /* dump the whole remainder of the buffer */
1120                                 next = tail;
1121                         strbuf_add(payload, line, next - line);
1122                         in_signature = 0;
1123                 }
1124                 line = next;
1125         }
1126  cleanup:
1127         free(buffer);
1128         return saw_signature;
1129 }
1130
1131 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1132 {
1133         struct merge_remote_desc *desc;
1134         struct commit_extra_header *mergetag;
1135         char *buf;
1136         unsigned long size, len;
1137         enum object_type type;
1138
1139         desc = merge_remote_util(parent);
1140         if (!desc || !desc->obj)
1141                 return;
1142         buf = read_sha1_file(desc->obj->sha1, &type, &size);
1143         if (!buf || type != OBJ_TAG)
1144                 goto free_return;
1145         len = parse_signature(buf, size);
1146         if (size == len)
1147                 goto free_return;
1148         /*
1149          * We could verify this signature and either omit the tag when
1150          * it does not validate, but the integrator may not have the
1151          * public key of the signer of the tag he is merging, while a
1152          * later auditor may have it while auditing, so let's not run
1153          * verify-signed-buffer here for now...
1154          *
1155          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1156          *      warn("warning: signed tag unverified.");
1157          */
1158         mergetag = xcalloc(1, sizeof(*mergetag));
1159         mergetag->key = xstrdup("mergetag");
1160         mergetag->value = buf;
1161         mergetag->len = size;
1162
1163         **tail = mergetag;
1164         *tail = &mergetag->next;
1165         return;
1166
1167 free_return:
1168         free(buf);
1169 }
1170
1171 static struct {
1172         char result;
1173         const char *check;
1174 } sigcheck_gpg_status[] = {
1175         { 'G', "\n[GNUPG:] GOODSIG " },
1176         { 'B', "\n[GNUPG:] BADSIG " },
1177         { 'U', "\n[GNUPG:] TRUST_NEVER" },
1178         { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1179 };
1180
1181 static void parse_gpg_output(struct signature_check *sigc)
1182 {
1183         const char *buf = sigc->gpg_status;
1184         int i;
1185
1186         /* Iterate over all search strings */
1187         for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1188                 const char *found, *next;
1189
1190                 if (starts_with(buf, sigcheck_gpg_status[i].check + 1)) {
1191                         /* At the very beginning of the buffer */
1192                         found = buf + strlen(sigcheck_gpg_status[i].check + 1);
1193                 } else {
1194                         found = strstr(buf, sigcheck_gpg_status[i].check);
1195                         if (!found)
1196                                 continue;
1197                         found += strlen(sigcheck_gpg_status[i].check);
1198                 }
1199                 sigc->result = sigcheck_gpg_status[i].result;
1200                 /* The trust messages are not followed by key/signer information */
1201                 if (sigc->result != 'U') {
1202                         sigc->key = xmemdupz(found, 16);
1203                         found += 17;
1204                         next = strchrnul(found, '\n');
1205                         sigc->signer = xmemdupz(found, next - found);
1206                 }
1207         }
1208 }
1209
1210 void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1211 {
1212         struct strbuf payload = STRBUF_INIT;
1213         struct strbuf signature = STRBUF_INIT;
1214         struct strbuf gpg_output = STRBUF_INIT;
1215         struct strbuf gpg_status = STRBUF_INIT;
1216         int status;
1217
1218         sigc->result = 'N';
1219
1220         if (parse_signed_commit(commit->object.sha1,
1221                                 &payload, &signature) <= 0)
1222                 goto out;
1223         status = verify_signed_buffer(payload.buf, payload.len,
1224                                       signature.buf, signature.len,
1225                                       &gpg_output, &gpg_status);
1226         if (status && !gpg_output.len)
1227                 goto out;
1228         sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1229         sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1230         parse_gpg_output(sigc);
1231
1232  out:
1233         strbuf_release(&gpg_status);
1234         strbuf_release(&gpg_output);
1235         strbuf_release(&payload);
1236         strbuf_release(&signature);
1237 }
1238
1239
1240
1241 void append_merge_tag_headers(struct commit_list *parents,
1242                               struct commit_extra_header ***tail)
1243 {
1244         while (parents) {
1245                 struct commit *parent = parents->item;
1246                 handle_signed_tag(parent, tail);
1247                 parents = parents->next;
1248         }
1249 }
1250
1251 static void add_extra_header(struct strbuf *buffer,
1252                              struct commit_extra_header *extra)
1253 {
1254         strbuf_addstr(buffer, extra->key);
1255         if (extra->len)
1256                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
1257         else
1258                 strbuf_addch(buffer, '\n');
1259 }
1260
1261 struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1262                                                       const char **exclude)
1263 {
1264         struct commit_extra_header *extra = NULL;
1265         unsigned long size;
1266         enum object_type type;
1267         char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1268         if (buffer && type == OBJ_COMMIT)
1269                 extra = read_commit_extra_header_lines(buffer, size, exclude);
1270         free(buffer);
1271         return extra;
1272 }
1273
1274 static inline int standard_header_field(const char *field, size_t len)
1275 {
1276         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1277                 (len == 6 && !memcmp(field, "parent ", 7)) ||
1278                 (len == 6 && !memcmp(field, "author ", 7)) ||
1279                 (len == 9 && !memcmp(field, "committer ", 10)) ||
1280                 (len == 8 && !memcmp(field, "encoding ", 9)));
1281 }
1282
1283 static int excluded_header_field(const char *field, size_t len, const char **exclude)
1284 {
1285         if (!exclude)
1286                 return 0;
1287
1288         while (*exclude) {
1289                 size_t xlen = strlen(*exclude);
1290                 if (len == xlen &&
1291                     !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1292                         return 1;
1293                 exclude++;
1294         }
1295         return 0;
1296 }
1297
1298 static struct commit_extra_header *read_commit_extra_header_lines(
1299         const char *buffer, size_t size,
1300         const char **exclude)
1301 {
1302         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1303         const char *line, *next, *eof, *eob;
1304         struct strbuf buf = STRBUF_INIT;
1305
1306         for (line = buffer, eob = line + size;
1307              line < eob && *line != '\n';
1308              line = next) {
1309                 next = memchr(line, '\n', eob - line);
1310                 next = next ? next + 1 : eob;
1311                 if (*line == ' ') {
1312                         /* continuation */
1313                         if (it)
1314                                 strbuf_add(&buf, line + 1, next - (line + 1));
1315                         continue;
1316                 }
1317                 if (it)
1318                         it->value = strbuf_detach(&buf, &it->len);
1319                 strbuf_reset(&buf);
1320                 it = NULL;
1321
1322                 eof = strchr(line, ' ');
1323                 if (next <= eof)
1324                         eof = next;
1325
1326                 if (standard_header_field(line, eof - line) ||
1327                     excluded_header_field(line, eof - line, exclude))
1328                         continue;
1329
1330                 it = xcalloc(1, sizeof(*it));
1331                 it->key = xmemdupz(line, eof-line);
1332                 *tail = it;
1333                 tail = &it->next;
1334                 if (eof + 1 < next)
1335                         strbuf_add(&buf, eof + 1, next - (eof + 1));
1336         }
1337         if (it)
1338                 it->value = strbuf_detach(&buf, &it->len);
1339         return extra;
1340 }
1341
1342 void free_commit_extra_headers(struct commit_extra_header *extra)
1343 {
1344         while (extra) {
1345                 struct commit_extra_header *next = extra->next;
1346                 free(extra->key);
1347                 free(extra->value);
1348                 free(extra);
1349                 extra = next;
1350         }
1351 }
1352
1353 int commit_tree(const struct strbuf *msg, const unsigned char *tree,
1354                 struct commit_list *parents, unsigned char *ret,
1355                 const char *author, const char *sign_commit)
1356 {
1357         struct commit_extra_header *extra = NULL, **tail = &extra;
1358         int result;
1359
1360         append_merge_tag_headers(parents, &tail);
1361         result = commit_tree_extended(msg, tree, parents, ret,
1362                                       author, sign_commit, extra);
1363         free_commit_extra_headers(extra);
1364         return result;
1365 }
1366
1367 static int find_invalid_utf8(const char *buf, int len)
1368 {
1369         int offset = 0;
1370         static const unsigned int max_codepoint[] = {
1371                 0x7f, 0x7ff, 0xffff, 0x10ffff
1372         };
1373
1374         while (len) {
1375                 unsigned char c = *buf++;
1376                 int bytes, bad_offset;
1377                 unsigned int codepoint;
1378                 unsigned int min_val, max_val;
1379
1380                 len--;
1381                 offset++;
1382
1383                 /* Simple US-ASCII? No worries. */
1384                 if (c < 0x80)
1385                         continue;
1386
1387                 bad_offset = offset-1;
1388
1389                 /*
1390                  * Count how many more high bits set: that's how
1391                  * many more bytes this sequence should have.
1392                  */
1393                 bytes = 0;
1394                 while (c & 0x40) {
1395                         c <<= 1;
1396                         bytes++;
1397                 }
1398
1399                 /*
1400                  * Must be between 1 and 3 more bytes.  Longer sequences result in
1401                  * codepoints beyond U+10FFFF, which are guaranteed never to exist.
1402                  */
1403                 if (bytes < 1 || 3 < bytes)
1404                         return bad_offset;
1405
1406                 /* Do we *have* that many bytes? */
1407                 if (len < bytes)
1408                         return bad_offset;
1409
1410                 /*
1411                  * Place the encoded bits at the bottom of the value and compute the
1412                  * valid range.
1413                  */
1414                 codepoint = (c & 0x7f) >> bytes;
1415                 min_val = max_codepoint[bytes-1] + 1;
1416                 max_val = max_codepoint[bytes];
1417
1418                 offset += bytes;
1419                 len -= bytes;
1420
1421                 /* And verify that they are good continuation bytes */
1422                 do {
1423                         codepoint <<= 6;
1424                         codepoint |= *buf & 0x3f;
1425                         if ((*buf++ & 0xc0) != 0x80)
1426                                 return bad_offset;
1427                 } while (--bytes);
1428
1429                 /* Reject codepoints that are out of range for the sequence length. */
1430                 if (codepoint < min_val || codepoint > max_val)
1431                         return bad_offset;
1432                 /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
1433                 if ((codepoint & 0x1ff800) == 0xd800)
1434                         return bad_offset;
1435                 /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
1436                 if ((codepoint & 0xfffe) == 0xfffe)
1437                         return bad_offset;
1438                 /* So are anything in the range U+FDD0..U+FDEF. */
1439                 if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
1440                         return bad_offset;
1441         }
1442         return -1;
1443 }
1444
1445 /*
1446  * This verifies that the buffer is in proper utf8 format.
1447  *
1448  * If it isn't, it assumes any non-utf8 characters are Latin1,
1449  * and does the conversion.
1450  */
1451 static int verify_utf8(struct strbuf *buf)
1452 {
1453         int ok = 1;
1454         long pos = 0;
1455
1456         for (;;) {
1457                 int bad;
1458                 unsigned char c;
1459                 unsigned char replace[2];
1460
1461                 bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1462                 if (bad < 0)
1463                         return ok;
1464                 pos += bad;
1465                 ok = 0;
1466                 c = buf->buf[pos];
1467                 strbuf_remove(buf, pos, 1);
1468
1469                 /* We know 'c' must be in the range 128-255 */
1470                 replace[0] = 0xc0 + (c >> 6);
1471                 replace[1] = 0x80 + (c & 0x3f);
1472                 strbuf_insert(buf, pos, replace, 2);
1473                 pos += 2;
1474         }
1475 }
1476
1477 static const char commit_utf8_warn[] =
1478 "Warning: commit message did not conform to UTF-8.\n"
1479 "You may want to amend it after fixing the message, or set the config\n"
1480 "variable i18n.commitencoding to the encoding your project uses.\n";
1481
1482 int commit_tree_extended(const struct strbuf *msg, const unsigned char *tree,
1483                          struct commit_list *parents, unsigned char *ret,
1484                          const char *author, const char *sign_commit,
1485                          struct commit_extra_header *extra)
1486 {
1487         int result;
1488         int encoding_is_utf8;
1489         struct strbuf buffer;
1490
1491         assert_sha1_type(tree, OBJ_TREE);
1492
1493         if (memchr(msg->buf, '\0', msg->len))
1494                 return error("a NUL byte in commit log message not allowed.");
1495
1496         /* Not having i18n.commitencoding is the same as having utf-8 */
1497         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1498
1499         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1500         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1501
1502         /*
1503          * NOTE! This ordering means that the same exact tree merged with a
1504          * different order of parents will be a _different_ changeset even
1505          * if everything else stays the same.
1506          */
1507         while (parents) {
1508                 struct commit_list *next = parents->next;
1509                 struct commit *parent = parents->item;
1510
1511                 strbuf_addf(&buffer, "parent %s\n",
1512                             sha1_to_hex(parent->object.sha1));
1513                 free(parents);
1514                 parents = next;
1515         }
1516
1517         /* Person/date information */
1518         if (!author)
1519                 author = git_author_info(IDENT_STRICT);
1520         strbuf_addf(&buffer, "author %s\n", author);
1521         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1522         if (!encoding_is_utf8)
1523                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1524
1525         while (extra) {
1526                 add_extra_header(&buffer, extra);
1527                 extra = extra->next;
1528         }
1529         strbuf_addch(&buffer, '\n');
1530
1531         /* And add the comment */
1532         strbuf_addbuf(&buffer, msg);
1533
1534         /* And check the encoding */
1535         if (encoding_is_utf8 && !verify_utf8(&buffer))
1536                 fprintf(stderr, commit_utf8_warn);
1537
1538         if (sign_commit && do_sign_commit(&buffer, sign_commit))
1539                 return -1;
1540
1541         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1542         strbuf_release(&buffer);
1543         return result;
1544 }
1545
1546 struct commit *get_merge_parent(const char *name)
1547 {
1548         struct object *obj;
1549         struct commit *commit;
1550         unsigned char sha1[20];
1551         if (get_sha1(name, sha1))
1552                 return NULL;
1553         obj = parse_object(sha1);
1554         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1555         if (commit && !commit->util) {
1556                 struct merge_remote_desc *desc;
1557                 desc = xmalloc(sizeof(*desc));
1558                 desc->obj = obj;
1559                 desc->name = strdup(name);
1560                 commit->util = desc;
1561         }
1562         return commit;
1563 }
1564
1565 /*
1566  * Append a commit to the end of the commit_list.
1567  *
1568  * next starts by pointing to the variable that holds the head of an
1569  * empty commit_list, and is updated to point to the "next" field of
1570  * the last item on the list as new commits are appended.
1571  *
1572  * Usage example:
1573  *
1574  *     struct commit_list *list;
1575  *     struct commit_list **next = &list;
1576  *
1577  *     next = commit_list_append(c1, next);
1578  *     next = commit_list_append(c2, next);
1579  *     assert(commit_list_count(list) == 2);
1580  *     return list;
1581  */
1582 struct commit_list **commit_list_append(struct commit *commit,
1583                                         struct commit_list **next)
1584 {
1585         struct commit_list *new = xmalloc(sizeof(struct commit_list));
1586         new->item = commit;
1587         *next = new;
1588         new->next = NULL;
1589         return &new->next;
1590 }
1591
1592 void print_commit_list(struct commit_list *list,
1593                        const char *format_cur,
1594                        const char *format_last)
1595 {
1596         for ( ; list; list = list->next) {
1597                 const char *format = list->next ? format_cur : format_last;
1598                 printf(format, sha1_to_hex(list->item->object.sha1));
1599         }
1600 }