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
  21 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  22                                               int quiet)
  23 {
  24         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  25
  26         if (!obj)
  27                 return NULL;
  28         return object_as_type(obj, OBJ_COMMIT, quiet);
  29 }
  30
  31 struct commit *lookup_commit_reference(const unsigned char *sha1)
  32 {
  33         return lookup_commit_reference_gently(sha1, 0);
  34 }
  35
  36 struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  37 {
  38         struct commit *c = lookup_commit_reference(sha1);
  39         if (!c)
  40                 die(_("could not parse %s"), ref_name);
  41         if (hashcmp(sha1, c->object.sha1)) {
  42                 warning(_("%s %s is not a commit!"),
  43                         ref_name, sha1_to_hex(sha1));
  44         }
  45         return c;
  46 }
  47
  48 struct commit *lookup_commit(const unsigned char *sha1)
  49 {
  50         struct object *obj = lookup_object(sha1);
  51         if (!obj)
  52                 return create_object(sha1, alloc_commit_node());
  53         return object_as_type(obj, OBJ_COMMIT, 0);
  54 }
  55
  56 struct commit *lookup_commit_reference_by_name(const char *name)
  57 {
  58         unsigned char sha1[20];
  59         struct commit *commit;
  60
  61         if (get_sha1_committish(name, sha1))
  62                 return NULL;
  63         commit = lookup_commit_reference(sha1);
  64         if (parse_commit(commit))
  65                 return NULL;
  66         return commit;
  67 }
  68
  69 static unsigned long parse_commit_date(const char *buf, const char *tail)
  70 {
  71         const char *dateptr;
  72
  73         if (buf + 6 >= tail)
  74                 return 0;
  75         if (memcmp(buf, "author", 6))
  76                 return 0;
  77         while (buf < tail && *buf++ != '\n')
  78                 /* nada */;
  79         if (buf + 9 >= tail)
  80                 return 0;
  81         if (memcmp(buf, "committer", 9))
  82                 return 0;
  83         while (buf < tail && *buf++ != '>')
  84                 /* nada */;
  85         if (buf >= tail)
  86                 return 0;
  87         dateptr = buf;
  88         while (buf < tail && *buf++ != '\n')
  89                 /* nada */;
  90         if (buf >= tail)
  91                 return 0;
  92         /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
  93         return strtoul(dateptr, NULL, 10);
  94 }
  95
  96 static struct commit_graft **commit_graft;
  97 static int commit_graft_alloc, commit_graft_nr;
  98
  99 static const unsigned char *commit_graft_sha1_access(size_t index, void *table)
 100 {
 101         struct commit_graft **commit_graft_table = table;
 102         return commit_graft_table[index]->sha1;
 103 }
 104
 105 static int commit_graft_pos(const unsigned char *sha1)
 106 {
 107         return sha1_pos(sha1, commit_graft, commit_graft_nr,
 108                         commit_graft_sha1_access);
 109 }
 110
 111 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 112 {
 113         int pos = commit_graft_pos(graft->sha1);
 114
 115         if (0 <= pos) {
 116                 if (ignore_dups)
 117                         free(graft);
 118                 else {
 119                         free(commit_graft[pos]);
 120                         commit_graft[pos] = graft;
 121                 }
 122                 return 1;
 123         }
 124         pos = -pos - 1;
 125         ALLOC_GROW(commit_graft, commit_graft_nr + 1, commit_graft_alloc);
 126         commit_graft_nr++;
 127         if (pos < commit_graft_nr)
 128                 memmove(commit_graft + pos + 1,
 129                         commit_graft + pos,
 130                         (commit_graft_nr - pos - 1) *
 131                         sizeof(*commit_graft));
 132         commit_graft[pos] = graft;
 133         return 0;
 134 }
 135
 136 struct commit_graft *read_graft_line(char *buf, int len)
 137 {
 138         /* The format is just "Commit Parent1 Parent2 ...\n" */
 139         int i;
 140         struct commit_graft *graft = NULL;
 141
 142         while (len && isspace(buf[len-1]))
 143                 buf[--len] = '\0';
 144         if (buf[0] == '#' || buf[0] == '\0')
 145                 return NULL;
 146         if ((len + 1) % 41)
 147                 goto bad_graft_data;
 148         i = (len + 1) / 41 - 1;
 149         graft = xmalloc(sizeof(*graft) + 20 * i);
 150         graft->nr_parent = i;
 151         if (get_sha1_hex(buf, graft->sha1))
 152                 goto bad_graft_data;
 153         for (i = 40; i < len; i += 41) {
 154                 if (buf[i] != ' ')
 155                         goto bad_graft_data;
 156                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 157                         goto bad_graft_data;
 158         }
 159         return graft;
 160
 161 bad_graft_data:
 162         error("bad graft data: %s", buf);
 163         free(graft);
 164         return NULL;
 165 }
 166
 167 static int read_graft_file(const char *graft_file)
 168 {
 169         FILE *fp = fopen(graft_file, "r");
 170         struct strbuf buf = STRBUF_INIT;
 171         if (!fp)
 172                 return -1;
 173         while (!strbuf_getwholeline(&buf, fp, '\n')) {
 174                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 175                 struct commit_graft *graft = read_graft_line(buf.buf, buf.len);
 176                 if (!graft)
 177                         continue;
 178                 if (register_commit_graft(graft, 1))
 179                         error("duplicate graft data: %s", buf.buf);
 180         }
 181         fclose(fp);
 182         strbuf_release(&buf);
 183         return 0;
 184 }
 185
 186 static void prepare_commit_graft(void)
 187 {
 188         static int commit_graft_prepared;
 189         char *graft_file;
 190
 191         if (commit_graft_prepared)
 192                 return;
 193         graft_file = get_graft_file();
 194         read_graft_file(graft_file);
 195         /* make sure shallows are read */
 196         is_repository_shallow();
 197         commit_graft_prepared = 1;
 198 }
 199
 200 struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 201 {
 202         int pos;
 203         prepare_commit_graft();
 204         pos = commit_graft_pos(sha1);
 205         if (pos < 0)
 206                 return NULL;
 207         return commit_graft[pos];
 208 }
 209
 210 int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 211 {
 212         int i, ret;
 213         for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 214                 ret = fn(commit_graft[i], cb_data);
 215         return ret;
 216 }
 217
 218 int unregister_shallow(const unsigned char *sha1)
 219 {
 220         int pos = commit_graft_pos(sha1);
 221         if (pos < 0)
 222                 return -1;
 223         if (pos + 1 < commit_graft_nr)
 224                 memmove(commit_graft + pos, commit_graft + pos + 1,
 225                                 sizeof(struct commit_graft *)
 226                                 * (commit_graft_nr - pos - 1));
 227         commit_graft_nr--;
 228         return 0;
 229 }
 230
 231 struct commit_buffer {
 232         void *buffer;
 233         unsigned long size;
 234 };
 235 define_commit_slab(buffer_slab, struct commit_buffer);
 236 static struct buffer_slab buffer_slab = COMMIT_SLAB_INIT(1, buffer_slab);
 237
 238 void set_commit_buffer(struct commit *commit, void *buffer, unsigned long size)
 239 {
 240         struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
 241         v->buffer = buffer;
 242         v->size = size;
 243 }
 244
 245 const void *get_cached_commit_buffer(const struct commit *commit, unsigned long *sizep)
 246 {
 247         struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
 248         if (sizep)
 249                 *sizep = v->size;
 250         return v->buffer;
 251 }
 252
 253 const void *get_commit_buffer(const struct commit *commit, unsigned long *sizep)
 254 {
 255         const void *ret = get_cached_commit_buffer(commit, sizep);
 256         if (!ret) {
 257                 enum object_type type;
 258                 unsigned long size;
 259                 ret = read_sha1_file(commit->object.sha1, &type, &size);
 260                 if (!ret)
 261                         die("cannot read commit object %s",
 262                             sha1_to_hex(commit->object.sha1));
 263                 if (type != OBJ_COMMIT)
 264                         die("expected commit for %s, got %s",
 265                             sha1_to_hex(commit->object.sha1), typename(type));
 266                 if (sizep)
 267                         *sizep = size;
 268         }
 269         return ret;
 270 }
 271
 272 void unuse_commit_buffer(const struct commit *commit, const void *buffer)
 273 {
 274         struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
 275         if (v->buffer != buffer)
 276                 free((void *)buffer);
 277 }
 278
 279 void free_commit_buffer(struct commit *commit)
 280 {
 281         struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
 282         free(v->buffer);
 283         v->buffer = NULL;
 284         v->size = 0;
 285 }
 286
 287 const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep)
 288 {
 289         struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
 290         void *ret;
 291
 292         ret = v->buffer;
 293         if (sizep)
 294                 *sizep = v->size;
 295
 296         v->buffer = NULL;
 297         v->size = 0;
 298         return ret;
 299 }
 300
 301 int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 302 {
 303         const char *tail = buffer;
 304         const char *bufptr = buffer;
 305         unsigned char parent[20];
 306         struct commit_list **pptr;
 307         struct commit_graft *graft;
 308
 309         if (item->object.parsed)
 310                 return 0;
 311         item->object.parsed = 1;
 312         tail += size;
 313         if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 314                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 315         if (get_sha1_hex(bufptr + 5, parent) < 0)
 316                 return error("bad tree pointer in commit %s",
 317                              sha1_to_hex(item->object.sha1));
 318         item->tree = lookup_tree(parent);
 319         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 320         pptr = &item->parents;
 321
 322         graft = lookup_commit_graft(item->object.sha1);
 323         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 324                 struct commit *new_parent;
 325
 326                 if (tail <= bufptr + 48 ||
 327                     get_sha1_hex(bufptr + 7, parent) ||
 328                     bufptr[47] != '\n')
 329                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 330                 bufptr += 48;
 331                 /*
 332                  * The clone is shallow if nr_parent < 0, and we must
 333                  * not traverse its real parents even when we unhide them.
 334                  */
 335                 if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 336                         continue;
 337                 new_parent = lookup_commit(parent);
 338                 if (new_parent)
 339                         pptr = &commit_list_insert(new_parent, pptr)->next;
 340         }
 341         if (graft) {
 342                 int i;
 343                 struct commit *new_parent;
 344                 for (i = 0; i < graft->nr_parent; i++) {
 345                         new_parent = lookup_commit(graft->parent[i]);
 346                         if (!new_parent)
 347                                 continue;
 348                         pptr = &commit_list_insert(new_parent, pptr)->next;
 349                 }
 350         }
 351         item->date = parse_commit_date(bufptr, tail);
 352
 353         return 0;
 354 }
 355
 356 int parse_commit(struct commit *item)
 357 {
 358         enum object_type type;
 359         void *buffer;
 360         unsigned long size;
 361         int ret;
 362
 363         if (!item)
 364                 return -1;
 365         if (item->object.parsed)
 366                 return 0;
 367         buffer = read_sha1_file(item->object.sha1, &type, &size);
 368         if (!buffer)
 369                 return error("Could not read %s",
 370                              sha1_to_hex(item->object.sha1));
 371         if (type != OBJ_COMMIT) {
 372                 free(buffer);
 373                 return error("Object %s not a commit",
 374                              sha1_to_hex(item->object.sha1));
 375         }
 376         ret = parse_commit_buffer(item, buffer, size);
 377         if (save_commit_buffer && !ret) {
 378                 set_commit_buffer(item, buffer, size);
 379                 return 0;
 380         }
 381         free(buffer);
 382         return ret;
 383 }
 384
 385 void parse_commit_or_die(struct commit *item)
 386 {
 387         if (parse_commit(item))
 388                 die("unable to parse commit %s",
 389                     item ? sha1_to_hex(item->object.sha1) : "(null)");
 390 }
 391
 392 int find_commit_subject(const char *commit_buffer, const char **subject)
 393 {
 394         const char *eol;
 395         const char *p = commit_buffer;
 396
 397         while (*p && (*p != '\n' || p[1] != '\n'))
 398                 p++;
 399         if (*p) {
 400                 p += 2;
 401                 for (eol = p; *eol && *eol != '\n'; eol++)
 402                         ; /* do nothing */
 403         } else
 404                 eol = p;
 405
 406         *subject = p;
 407
 408         return eol - p;
 409 }
 410
 411 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 412 {
 413         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 414         new_list->item = item;
 415         new_list->next = *list_p;
 416         *list_p = new_list;
 417         return new_list;
 418 }
 419
 420 unsigned commit_list_count(const struct commit_list *l)
 421 {
 422         unsigned c = 0;
 423         for (; l; l = l->next )
 424                 c++;
 425         return c;
 426 }
 427
 428 struct commit_list *copy_commit_list(struct commit_list *list)
 429 {
 430         struct commit_list *head = NULL;
 431         struct commit_list **pp = &head;
 432         while (list) {
 433                 pp = commit_list_append(list->item, pp);
 434                 list = list->next;
 435         }
 436         return head;
 437 }
 438
 439 void free_commit_list(struct commit_list *list)
 440 {
 441         while (list) {
 442                 struct commit_list *temp = list;
 443                 list = temp->next;
 444                 free(temp);
 445         }
 446 }
 447
 448 struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 449 {
 450         struct commit_list **pp = list;
 451         struct commit_list *p;
 452         while ((p = *pp) != NULL) {
 453                 if (p->item->date < item->date) {
 454                         break;
 455                 }
 456                 pp = &p->next;
 457         }
 458         return commit_list_insert(item, pp);
 459 }
 460
 461 static int commit_list_compare_by_date(const void *a, const void *b)
 462 {
 463         unsigned long a_date = ((const struct commit_list *)a)->item->date;
 464         unsigned long b_date = ((const struct commit_list *)b)->item->date;
 465         if (a_date < b_date)
 466                 return 1;
 467         if (a_date > b_date)
 468                 return -1;
 469         return 0;
 470 }
 471
 472 static void *commit_list_get_next(const void *a)
 473 {
 474         return ((const struct commit_list *)a)->next;
 475 }
 476
 477 static void commit_list_set_next(void *a, void *next)
 478 {
 479         ((struct commit_list *)a)->next = next;
 480 }
 481
 482 void commit_list_sort_by_date(struct commit_list **list)
 483 {
 484         *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 485                                 commit_list_compare_by_date);
 486 }
 487
 488 struct commit *pop_most_recent_commit(struct commit_list **list,
 489                                       unsigned int mark)
 490 {
 491         struct commit *ret = (*list)->item;
 492         struct commit_list *parents = ret->parents;
 493         struct commit_list *old = *list;
 494
 495         *list = (*list)->next;
 496         free(old);
 497
 498         while (parents) {
 499                 struct commit *commit = parents->item;
 500                 if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 501                         commit->object.flags |= mark;
 502                         commit_list_insert_by_date(commit, list);
 503                 }
 504                 parents = parents->next;
 505         }
 506         return ret;
 507 }
 508
 509 static void clear_commit_marks_1(struct commit_list **plist,
 510                                  struct commit *commit, unsigned int mark)
 511 {
 512         while (commit) {
 513                 struct commit_list *parents;
 514
 515                 if (!(mark & commit->object.flags))
 516                         return;
 517
 518                 commit->object.flags &= ~mark;
 519
 520                 parents = commit->parents;
 521                 if (!parents)
 522                         return;
 523
 524                 while ((parents = parents->next))
 525                         commit_list_insert(parents->item, plist);
 526
 527                 commit = commit->parents->item;
 528         }
 529 }
 530
 531 void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 532 {
 533         struct commit_list *list = NULL;
 534
 535         while (nr--) {
 536                 commit_list_insert(*commit, &list);
 537                 commit++;
 538         }
 539         while (list)
 540                 clear_commit_marks_1(&list, pop_commit(&list), mark);
 541 }
 542
 543 void clear_commit_marks(struct commit *commit, unsigned int mark)
 544 {
 545         clear_commit_marks_many(1, &commit, mark);
 546 }
 547
 548 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 549 {
 550         struct object *object;
 551         struct commit *commit;
 552         unsigned int i;
 553
 554         for (i = 0; i < a->nr; i++) {
 555                 object = a->objects[i].item;
 556                 commit = lookup_commit_reference_gently(object->sha1, 1);
 557                 if (commit)
 558                         clear_commit_marks(commit, mark);
 559         }
 560 }
 561
 562 struct commit *pop_commit(struct commit_list **stack)
 563 {
 564         struct commit_list *top = *stack;
 565         struct commit *item = top ? top->item : NULL;
 566
 567         if (top) {
 568                 *stack = top->next;
 569                 free(top);
 570         }
 571         return item;
 572 }
 573
 574 /*
 575  * Topological sort support
 576  */
 577
 578 /* count number of children that have not been emitted */
 579 define_commit_slab(indegree_slab, int);
 580
 581 /* record author-date for each commit object */
 582 define_commit_slab(author_date_slab, unsigned long);
 583
 584 static void record_author_date(struct author_date_slab *author_date,
 585                                struct commit *commit)
 586 {
 587         const char *buf, *line_end, *ident_line;
 588         const char *buffer = get_commit_buffer(commit, NULL);
 589         struct ident_split ident;
 590         char *date_end;
 591         unsigned long date;
 592
 593         for (buf = buffer; buf; buf = line_end + 1) {
 594                 line_end = strchrnul(buf, '\n');
 595                 if (!skip_prefix(buf, "author ", &ident_line)) {
 596                         if (!line_end[0] || line_end[1] == '\n')
 597                                 return; /* end of header */
 598                         continue;
 599                 }
 600                 if (split_ident_line(&ident,
 601                                      ident_line, line_end - ident_line) ||
 602                     !ident.date_begin || !ident.date_end)
 603                         goto fail_exit; /* malformed "author" line */
 604                 break;
 605         }
 606
 607         date = strtoul(ident.date_begin, &date_end, 10);
 608         if (date_end != ident.date_end)
 609                 goto fail_exit; /* malformed date */
 610         *(author_date_slab_at(author_date, commit)) = date;
 611
 612 fail_exit:
 613         unuse_commit_buffer(commit, buffer);
 614 }
 615
 616 static int compare_commits_by_author_date(const void *a_, const void *b_,
 617                                           void *cb_data)
 618 {
 619         const struct commit *a = a_, *b = b_;
 620         struct author_date_slab *author_date = cb_data;
 621         unsigned long a_date = *(author_date_slab_at(author_date, a));
 622         unsigned long b_date = *(author_date_slab_at(author_date, b));
 623
 624         /* newer commits with larger date first */
 625         if (a_date < b_date)
 626                 return 1;
 627         else if (a_date > b_date)
 628                 return -1;
 629         return 0;
 630 }
 631
 632 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 633 {
 634         const struct commit *a = a_, *b = b_;
 635         /* newer commits with larger date first */
 636         if (a->date < b->date)
 637                 return 1;
 638         else if (a->date > b->date)
 639                 return -1;
 640         return 0;
 641 }
 642
 643 /*
 644  * Performs an in-place topological sort on the list supplied.
 645  */
 646 void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 647 {
 648         struct commit_list *next, *orig = *list;
 649         struct commit_list **pptr;
 650         struct indegree_slab indegree;
 651         struct prio_queue queue;
 652         struct commit *commit;
 653         struct author_date_slab author_date;
 654
 655         if (!orig)
 656                 return;
 657         *list = NULL;
 658
 659         init_indegree_slab(&indegree);
 660         memset(&queue, '\0', sizeof(queue));
 661
 662         switch (sort_order) {
 663         default: /* REV_SORT_IN_GRAPH_ORDER */
 664                 queue.compare = NULL;
 665                 break;
 666         case REV_SORT_BY_COMMIT_DATE:
 667                 queue.compare = compare_commits_by_commit_date;
 668                 break;
 669         case REV_SORT_BY_AUTHOR_DATE:
 670                 init_author_date_slab(&author_date);
 671                 queue.compare = compare_commits_by_author_date;
 672                 queue.cb_data = &author_date;
 673                 break;
 674         }
 675
 676         /* Mark them and clear the indegree */
 677         for (next = orig; next; next = next->next) {
 678                 struct commit *commit = next->item;
 679                 *(indegree_slab_at(&indegree, commit)) = 1;
 680                 /* also record the author dates, if needed */
 681                 if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 682                         record_author_date(&author_date, commit);
 683         }
 684
 685         /* update the indegree */
 686         for (next = orig; next; next = next->next) {
 687                 struct commit_list *parents = next->item->parents;
 688                 while (parents) {
 689                         struct commit *parent = parents->item;
 690                         int *pi = indegree_slab_at(&indegree, parent);
 691
 692                         if (*pi)
 693                                 (*pi)++;
 694                         parents = parents->next;
 695                 }
 696         }
 697
 698         /*
 699          * find the tips
 700          *
 701          * tips are nodes not reachable from any other node in the list
 702          *
 703          * the tips serve as a starting set for the work queue.
 704          */
 705         for (next = orig; next; next = next->next) {
 706                 struct commit *commit = next->item;
 707
 708                 if (*(indegree_slab_at(&indegree, commit)) == 1)
 709                         prio_queue_put(&queue, commit);
 710         }
 711
 712         /*
 713          * This is unfortunate; the initial tips need to be shown
 714          * in the order given from the revision traversal machinery.
 715          */
 716         if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 717                 prio_queue_reverse(&queue);
 718
 719         /* We no longer need the commit list */
 720         free_commit_list(orig);
 721
 722         pptr = list;
 723         *list = NULL;
 724         while ((commit = prio_queue_get(&queue)) != NULL) {
 725                 struct commit_list *parents;
 726
 727                 for (parents = commit->parents; parents ; parents = parents->next) {
 728                         struct commit *parent = parents->item;
 729                         int *pi = indegree_slab_at(&indegree, parent);
 730
 731                         if (!*pi)
 732                                 continue;
 733
 734                         /*
 735                          * parents are only enqueued for emission
 736                          * when all their children have been emitted thereby
 737                          * guaranteeing topological order.
 738                          */
 739                         if (--(*pi) == 1)
 740                                 prio_queue_put(&queue, parent);
 741                 }
 742                 /*
 743                  * all children of commit have already been
 744                  * emitted. we can emit it now.
 745                  */
 746                 *(indegree_slab_at(&indegree, commit)) = 0;
 747
 748                 pptr = &commit_list_insert(commit, pptr)->next;
 749         }
 750
 751         clear_indegree_slab(&indegree);
 752         clear_prio_queue(&queue);
 753         if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 754                 clear_author_date_slab(&author_date);
 755 }
 756
 757 /* merge-base stuff */
 758
 759 /* Remember to update object flag allocation in object.h */
 760 #define PARENT1         (1u<<16)
 761 #define PARENT2         (1u<<17)
 762 #define STALE           (1u<<18)
 763 #define RESULT          (1u<<19)
 764
 765 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 766
 767 static struct commit *interesting(struct commit_list *list)
 768 {
 769         while (list) {
 770                 struct commit *commit = list->item;
 771                 list = list->next;
 772                 if (commit->object.flags & STALE)
 773                         continue;
 774                 return commit;
 775         }
 776         return NULL;
 777 }
 778
 779 /* all input commits in one and twos[] must have been parsed! */
 780 static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 781 {
 782         struct commit_list *list = NULL;
 783         struct commit_list *result = NULL;
 784         int i;
 785
 786         one->object.flags |= PARENT1;
 787         commit_list_insert_by_date(one, &list);
 788         if (!n)
 789                 return list;
 790         for (i = 0; i < n; i++) {
 791                 twos[i]->object.flags |= PARENT2;
 792                 commit_list_insert_by_date(twos[i], &list);
 793         }
 794
 795         while (interesting(list)) {
 796                 struct commit *commit;
 797                 struct commit_list *parents;
 798                 struct commit_list *next;
 799                 int flags;
 800
 801                 commit = list->item;
 802                 next = list->next;
 803                 free(list);
 804                 list = next;
 805
 806                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 807                 if (flags == (PARENT1 | PARENT2)) {
 808                         if (!(commit->object.flags & RESULT)) {
 809                                 commit->object.flags |= RESULT;
 810                                 commit_list_insert_by_date(commit, &result);
 811                         }
 812                         /* Mark parents of a found merge stale */
 813                         flags |= STALE;
 814                 }
 815                 parents = commit->parents;
 816                 while (parents) {
 817                         struct commit *p = parents->item;
 818                         parents = parents->next;
 819                         if ((p->object.flags & flags) == flags)
 820                                 continue;
 821                         if (parse_commit(p))
 822                                 return NULL;
 823                         p->object.flags |= flags;
 824                         commit_list_insert_by_date(p, &list);
 825                 }
 826         }
 827
 828         free_commit_list(list);
 829         return result;
 830 }
 831
 832 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 833 {
 834         struct commit_list *list = NULL;
 835         struct commit_list *result = NULL;
 836         int i;
 837
 838         for (i = 0; i < n; i++) {
 839                 if (one == twos[i])
 840                         /*
 841                          * We do not mark this even with RESULT so we do not
 842                          * have to clean it up.
 843                          */
 844                         return commit_list_insert(one, &result);
 845         }
 846
 847         if (parse_commit(one))
 848                 return NULL;
 849         for (i = 0; i < n; i++) {
 850                 if (parse_commit(twos[i]))
 851                         return NULL;
 852         }
 853
 854         list = paint_down_to_common(one, n, twos);
 855
 856         while (list) {
 857                 struct commit_list *next = list->next;
 858                 if (!(list->item->object.flags & STALE))
 859                         commit_list_insert_by_date(list->item, &result);
 860                 free(list);
 861                 list = next;
 862         }
 863         return result;
 864 }
 865
 866 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 867 {
 868         struct commit_list *i, *j, *k, *ret = NULL;
 869
 870         if (!in)
 871                 return ret;
 872
 873         commit_list_insert(in->item, &ret);
 874
 875         for (i = in->next; i; i = i->next) {
 876                 struct commit_list *new = NULL, *end = NULL;
 877
 878                 for (j = ret; j; j = j->next) {
 879                         struct commit_list *bases;
 880                         bases = get_merge_bases(i->item, j->item, 1);
 881                         if (!new)
 882                                 new = bases;
 883                         else
 884                                 end->next = bases;
 885                         for (k = bases; k; k = k->next)
 886                                 end = k;
 887                 }
 888                 ret = new;
 889         }
 890         return ret;
 891 }
 892
 893 static int remove_redundant(struct commit **array, int cnt)
 894 {
 895         /*
 896          * Some commit in the array may be an ancestor of
 897          * another commit.  Move such commit to the end of
 898          * the array, and return the number of commits that
 899          * are independent from each other.
 900          */
 901         struct commit **work;
 902         unsigned char *redundant;
 903         int *filled_index;
 904         int i, j, filled;
 905
 906         work = xcalloc(cnt, sizeof(*work));
 907         redundant = xcalloc(cnt, 1);
 908         filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 909
 910         for (i = 0; i < cnt; i++)
 911                 parse_commit(array[i]);
 912         for (i = 0; i < cnt; i++) {
 913                 struct commit_list *common;
 914
 915                 if (redundant[i])
 916                         continue;
 917                 for (j = filled = 0; j < cnt; j++) {
 918                         if (i == j || redundant[j])
 919                                 continue;
 920                         filled_index[filled] = j;
 921                         work[filled++] = array[j];
 922                 }
 923                 common = paint_down_to_common(array[i], filled, work);
 924                 if (array[i]->object.flags & PARENT2)
 925                         redundant[i] = 1;
 926                 for (j = 0; j < filled; j++)
 927                         if (work[j]->object.flags & PARENT1)
 928                                 redundant[filled_index[j]] = 1;
 929                 clear_commit_marks(array[i], all_flags);
 930                 for (j = 0; j < filled; j++)
 931                         clear_commit_marks(work[j], all_flags);
 932                 free_commit_list(common);
 933         }
 934
 935         /* Now collect the result */
 936         memcpy(work, array, sizeof(*array) * cnt);
 937         for (i = filled = 0; i < cnt; i++)
 938                 if (!redundant[i])
 939                         array[filled++] = work[i];
 940         for (j = filled, i = 0; i < cnt; i++)
 941                 if (redundant[i])
 942                         array[j++] = work[i];
 943         free(work);
 944         free(redundant);
 945         free(filled_index);
 946         return filled;
 947 }
 948
 949 struct commit_list *get_merge_bases_many(struct commit *one,
 950                                          int n,
 951                                          struct commit **twos,
 952                                          int cleanup)
 953 {
 954         struct commit_list *list;
 955         struct commit **rslt;
 956         struct commit_list *result;
 957         int cnt, i;
 958
 959         result = merge_bases_many(one, n, twos);
 960         for (i = 0; i < n; i++) {
 961                 if (one == twos[i])
 962                         return result;
 963         }
 964         if (!result || !result->next) {
 965                 if (cleanup) {
 966                         clear_commit_marks(one, all_flags);
 967                         clear_commit_marks_many(n, twos, all_flags);
 968                 }
 969                 return result;
 970         }
 971
 972         /* There are more than one */
 973         cnt = commit_list_count(result);
 974         rslt = xcalloc(cnt, sizeof(*rslt));
 975         for (list = result, i = 0; list; list = list->next)
 976                 rslt[i++] = list->item;
 977         free_commit_list(result);
 978
 979         clear_commit_marks(one, all_flags);
 980         clear_commit_marks_many(n, twos, all_flags);
 981
 982         cnt = remove_redundant(rslt, cnt);
 983         result = NULL;
 984         for (i = 0; i < cnt; i++)
 985                 commit_list_insert_by_date(rslt[i], &result);
 986         free(rslt);
 987         return result;
 988 }
 989
 990 struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 991                                     int cleanup)
 992 {
 993         return get_merge_bases_many(one, 1, &two, cleanup);
 994 }
 995
 996 /*
 997  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 998  */
 999 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
1000 {
1001         if (!with_commit)
1002                 return 1;
1003         while (with_commit) {
1004                 struct commit *other;
1005
1006                 other = with_commit->item;
1007                 with_commit = with_commit->next;
1008                 if (in_merge_bases(other, commit))
1009                         return 1;
1010         }
1011         return 0;
1012 }
1013
1014 /*
1015  * Is "commit" an ancestor of one of the "references"?
1016  */
1017 int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
1018 {
1019         struct commit_list *bases;
1020         int ret = 0, i;
1021
1022         if (parse_commit(commit))
1023                 return ret;
1024         for (i = 0; i < nr_reference; i++)
1025                 if (parse_commit(reference[i]))
1026                         return ret;
1027
1028         bases = paint_down_to_common(commit, nr_reference, reference);
1029         if (commit->object.flags & PARENT2)
1030                 ret = 1;
1031         clear_commit_marks(commit, all_flags);
1032         clear_commit_marks_many(nr_reference, reference, all_flags);
1033         free_commit_list(bases);
1034         return ret;
1035 }
1036
1037 /*
1038  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
1039  */
1040 int in_merge_bases(struct commit *commit, struct commit *reference)
1041 {
1042         return in_merge_bases_many(commit, 1, &reference);
1043 }
1044
1045 struct commit_list *reduce_heads(struct commit_list *heads)
1046 {
1047         struct commit_list *p;
1048         struct commit_list *result = NULL, **tail = &result;
1049         struct commit **array;
1050         int num_head, i;
1051
1052         if (!heads)
1053                 return NULL;
1054
1055         /* Uniquify */
1056         for (p = heads; p; p = p->next)
1057                 p->item->object.flags &= ~STALE;
1058         for (p = heads, num_head = 0; p; p = p->next) {
1059                 if (p->item->object.flags & STALE)
1060                         continue;
1061                 p->item->object.flags |= STALE;
1062                 num_head++;
1063         }
1064         array = xcalloc(num_head, sizeof(*array));
1065         for (p = heads, i = 0; p; p = p->next) {
1066                 if (p->item->object.flags & STALE) {
1067                         array[i++] = p->item;
1068                         p->item->object.flags &= ~STALE;
1069                 }
1070         }
1071         num_head = remove_redundant(array, num_head);
1072         for (i = 0; i < num_head; i++)
1073                 tail = &commit_list_insert(array[i], tail)->next;
1074         return result;
1075 }
1076
1077 static const char gpg_sig_header[] = "gpgsig";
1078 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1079
1080 static int do_sign_commit(struct strbuf *buf, const char *keyid)
1081 {
1082         struct strbuf sig = STRBUF_INIT;
1083         int inspos, copypos;
1084
1085         /* find the end of the header */
1086         inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1087
1088         if (!keyid || !*keyid)
1089                 keyid = get_signing_key();
1090         if (sign_buffer(buf, &sig, keyid)) {
1091                 strbuf_release(&sig);
1092                 return -1;
1093         }
1094
1095         for (copypos = 0; sig.buf[copypos]; ) {
1096                 const char *bol = sig.buf + copypos;
1097                 const char *eol = strchrnul(bol, '\n');
1098                 int len = (eol - bol) + !!*eol;
1099
1100                 if (!copypos) {
1101                         strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1102                         inspos += gpg_sig_header_len;
1103                 }
1104                 strbuf_insert(buf, inspos++, " ", 1);
1105                 strbuf_insert(buf, inspos, bol, len);
1106                 inspos += len;
1107                 copypos += len;
1108         }
1109         strbuf_release(&sig);
1110         return 0;
1111 }
1112
1113 int parse_signed_commit(const struct commit *commit,
1114                         struct strbuf *payload, struct strbuf *signature)
1115 {
1116
1117         unsigned long size;
1118         const char *buffer = get_commit_buffer(commit, &size);
1119         int in_signature, saw_signature = -1;
1120         const char *line, *tail;
1121
1122         line = buffer;
1123         tail = buffer + size;
1124         in_signature = 0;
1125         saw_signature = 0;
1126         while (line < tail) {
1127                 const char *sig = NULL;
1128                 const char *next = memchr(line, '\n', tail - line);
1129
1130                 next = next ? next + 1 : tail;
1131                 if (in_signature && line[0] == ' ')
1132                         sig = line + 1;
1133                 else if (starts_with(line, gpg_sig_header) &&
1134                          line[gpg_sig_header_len] == ' ')
1135                         sig = line + gpg_sig_header_len + 1;
1136                 if (sig) {
1137                         strbuf_add(signature, sig, next - sig);
1138                         saw_signature = 1;
1139                         in_signature = 1;
1140                 } else {
1141                         if (*line == '\n')
1142                                 /* dump the whole remainder of the buffer */
1143                                 next = tail;
1144                         strbuf_add(payload, line, next - line);
1145                         in_signature = 0;
1146                 }
1147                 line = next;
1148         }
1149         unuse_commit_buffer(commit, buffer);
1150         return saw_signature;
1151 }
1152
1153 static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1154 {
1155         struct merge_remote_desc *desc;
1156         struct commit_extra_header *mergetag;
1157         char *buf;
1158         unsigned long size, len;
1159         enum object_type type;
1160
1161         desc = merge_remote_util(parent);
1162         if (!desc || !desc->obj)
1163                 return;
1164         buf = read_sha1_file(desc->obj->sha1, &type, &size);
1165         if (!buf || type != OBJ_TAG)
1166                 goto free_return;
1167         len = parse_signature(buf, size);
1168         if (size == len)
1169                 goto free_return;
1170         /*
1171          * We could verify this signature and either omit the tag when
1172          * it does not validate, but the integrator may not have the
1173          * public key of the signer of the tag he is merging, while a
1174          * later auditor may have it while auditing, so let's not run
1175          * verify-signed-buffer here for now...
1176          *
1177          * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1178          *      warn("warning: signed tag unverified.");
1179          */
1180         mergetag = xcalloc(1, sizeof(*mergetag));
1181         mergetag->key = xstrdup("mergetag");
1182         mergetag->value = buf;
1183         mergetag->len = size;
1184
1185         **tail = mergetag;
1186         *tail = &mergetag->next;
1187         return;
1188
1189 free_return:
1190         free(buf);
1191 }
1192
1193 static struct {
1194         char result;
1195         const char *check;
1196 } sigcheck_gpg_status[] = {
1197         { 'G', "\n[GNUPG:] GOODSIG " },
1198         { 'B', "\n[GNUPG:] BADSIG " },
1199         { 'U', "\n[GNUPG:] TRUST_NEVER" },
1200         { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1201 };
1202
1203 static void parse_gpg_output(struct signature_check *sigc)
1204 {
1205         const char *buf = sigc->gpg_status;
1206         int i;
1207
1208         /* Iterate over all search strings */
1209         for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1210                 const char *found, *next;
1211
1212                 if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
1213                         found = strstr(buf, sigcheck_gpg_status[i].check);
1214                         if (!found)
1215                                 continue;
1216                         found += strlen(sigcheck_gpg_status[i].check);
1217                 }
1218                 sigc->result = sigcheck_gpg_status[i].result;
1219                 /* The trust messages are not followed by key/signer information */
1220                 if (sigc->result != 'U') {
1221                         sigc->key = xmemdupz(found, 16);
1222                         found += 17;
1223                         next = strchrnul(found, '\n');
1224                         sigc->signer = xmemdupz(found, next - found);
1225                 }
1226         }
1227 }
1228
1229 void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1230 {
1231         struct strbuf payload = STRBUF_INIT;
1232         struct strbuf signature = STRBUF_INIT;
1233         struct strbuf gpg_output = STRBUF_INIT;
1234         struct strbuf gpg_status = STRBUF_INIT;
1235         int status;
1236
1237         sigc->result = 'N';
1238
1239         if (parse_signed_commit(commit, &payload, &signature) <= 0)
1240                 goto out;
1241         status = verify_signed_buffer(payload.buf, payload.len,
1242                                       signature.buf, signature.len,
1243                                       &gpg_output, &gpg_status);
1244         if (status && !gpg_output.len)
1245                 goto out;
1246         sigc->payload = strbuf_detach(&payload, NULL);
1247         sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1248         sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1249         parse_gpg_output(sigc);
1250
1251  out:
1252         strbuf_release(&gpg_status);
1253         strbuf_release(&gpg_output);
1254         strbuf_release(&payload);
1255         strbuf_release(&signature);
1256 }
1257
1258
1259
1260 void append_merge_tag_headers(struct commit_list *parents,
1261                               struct commit_extra_header ***tail)
1262 {
1263         while (parents) {
1264                 struct commit *parent = parents->item;
1265                 handle_signed_tag(parent, tail);
1266                 parents = parents->next;
1267         }
1268 }
1269
1270 static void add_extra_header(struct strbuf *buffer,
1271                              struct commit_extra_header *extra)
1272 {
1273         strbuf_addstr(buffer, extra->key);
1274         if (extra->len)
1275                 strbuf_add_lines(buffer, " ", extra->value, extra->len);
1276         else
1277                 strbuf_addch(buffer, '\n');
1278 }
1279
1280 struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1281                                                       const char **exclude)
1282 {
1283         struct commit_extra_header *extra = NULL;
1284         unsigned long size;
1285         const char *buffer = get_commit_buffer(commit, &size);
1286         extra = read_commit_extra_header_lines(buffer, size, exclude);
1287         unuse_commit_buffer(commit, buffer);
1288         return extra;
1289 }
1290
1291 void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
1292 {
1293         struct commit_extra_header *extra, *to_free;
1294
1295         to_free = read_commit_extra_headers(commit, NULL);
1296         for (extra = to_free; extra; extra = extra->next) {
1297                 if (strcmp(extra->key, "mergetag"))
1298                         continue; /* not a merge tag */
1299                 fn(commit, extra, data);
1300         }
1301         free_commit_extra_headers(to_free);
1302 }
1303
1304 static inline int standard_header_field(const char *field, size_t len)
1305 {
1306         return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1307                 (len == 6 && !memcmp(field, "parent ", 7)) ||
1308                 (len == 6 && !memcmp(field, "author ", 7)) ||
1309                 (len == 9 && !memcmp(field, "committer ", 10)) ||
1310                 (len == 8 && !memcmp(field, "encoding ", 9)));
1311 }
1312
1313 static int excluded_header_field(const char *field, size_t len, const char **exclude)
1314 {
1315         if (!exclude)
1316                 return 0;
1317
1318         while (*exclude) {
1319                 size_t xlen = strlen(*exclude);
1320                 if (len == xlen &&
1321                     !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1322                         return 1;
1323                 exclude++;
1324         }
1325         return 0;
1326 }
1327
1328 static struct commit_extra_header *read_commit_extra_header_lines(
1329         const char *buffer, size_t size,
1330         const char **exclude)
1331 {
1332         struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1333         const char *line, *next, *eof, *eob;
1334         struct strbuf buf = STRBUF_INIT;
1335
1336         for (line = buffer, eob = line + size;
1337              line < eob && *line != '\n';
1338              line = next) {
1339                 next = memchr(line, '\n', eob - line);
1340                 next = next ? next + 1 : eob;
1341                 if (*line == ' ') {
1342                         /* continuation */
1343                         if (it)
1344                                 strbuf_add(&buf, line + 1, next - (line + 1));
1345                         continue;
1346                 }
1347                 if (it)
1348                         it->value = strbuf_detach(&buf, &it->len);
1349                 strbuf_reset(&buf);
1350                 it = NULL;
1351
1352                 eof = strchr(line, ' ');
1353                 if (next <= eof)
1354                         eof = next;
1355
1356                 if (standard_header_field(line, eof - line) ||
1357                     excluded_header_field(line, eof - line, exclude))
1358                         continue;
1359
1360                 it = xcalloc(1, sizeof(*it));
1361                 it->key = xmemdupz(line, eof-line);
1362                 *tail = it;
1363                 tail = &it->next;
1364                 if (eof + 1 < next)
1365                         strbuf_add(&buf, eof + 1, next - (eof + 1));
1366         }
1367         if (it)
1368                 it->value = strbuf_detach(&buf, &it->len);
1369         return extra;
1370 }
1371
1372 void free_commit_extra_headers(struct commit_extra_header *extra)
1373 {
1374         while (extra) {
1375                 struct commit_extra_header *next = extra->next;
1376                 free(extra->key);
1377                 free(extra->value);
1378                 free(extra);
1379                 extra = next;
1380         }
1381 }
1382
1383 int commit_tree(const char *msg, size_t msg_len,
1384                 const unsigned char *tree,
1385                 struct commit_list *parents, unsigned char *ret,
1386                 const char *author, const char *sign_commit)
1387 {
1388         struct commit_extra_header *extra = NULL, **tail = &extra;
1389         int result;
1390
1391         append_merge_tag_headers(parents, &tail);
1392         result = commit_tree_extended(msg, msg_len, tree, parents, ret,
1393                                       author, sign_commit, extra);
1394         free_commit_extra_headers(extra);
1395         return result;
1396 }
1397
1398 static int find_invalid_utf8(const char *buf, int len)
1399 {
1400         int offset = 0;
1401         static const unsigned int max_codepoint[] = {
1402                 0x7f, 0x7ff, 0xffff, 0x10ffff
1403         };
1404
1405         while (len) {
1406                 unsigned char c = *buf++;
1407                 int bytes, bad_offset;
1408                 unsigned int codepoint;
1409                 unsigned int min_val, max_val;
1410
1411                 len--;
1412                 offset++;
1413
1414                 /* Simple US-ASCII? No worries. */
1415                 if (c < 0x80)
1416                         continue;
1417
1418                 bad_offset = offset-1;
1419
1420                 /*
1421                  * Count how many more high bits set: that's how
1422                  * many more bytes this sequence should have.
1423                  */
1424                 bytes = 0;
1425                 while (c & 0x40) {
1426                         c <<= 1;
1427                         bytes++;
1428                 }
1429
1430                 /*
1431                  * Must be between 1 and 3 more bytes.  Longer sequences result in
1432                  * codepoints beyond U+10FFFF, which are guaranteed never to exist.
1433                  */
1434                 if (bytes < 1 || 3 < bytes)
1435                         return bad_offset;
1436
1437                 /* Do we *have* that many bytes? */
1438                 if (len < bytes)
1439                         return bad_offset;
1440
1441                 /*
1442                  * Place the encoded bits at the bottom of the value and compute the
1443                  * valid range.
1444                  */
1445                 codepoint = (c & 0x7f) >> bytes;
1446                 min_val = max_codepoint[bytes-1] + 1;
1447                 max_val = max_codepoint[bytes];
1448
1449                 offset += bytes;
1450                 len -= bytes;
1451
1452                 /* And verify that they are good continuation bytes */
1453                 do {
1454                         codepoint <<= 6;
1455                         codepoint |= *buf & 0x3f;
1456                         if ((*buf++ & 0xc0) != 0x80)
1457                                 return bad_offset;
1458                 } while (--bytes);
1459
1460                 /* Reject codepoints that are out of range for the sequence length. */
1461                 if (codepoint < min_val || codepoint > max_val)
1462                         return bad_offset;
1463                 /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
1464                 if ((codepoint & 0x1ff800) == 0xd800)
1465                         return bad_offset;
1466                 /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
1467                 if ((codepoint & 0xfffe) == 0xfffe)
1468                         return bad_offset;
1469                 /* So are anything in the range U+FDD0..U+FDEF. */
1470                 if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
1471                         return bad_offset;
1472         }
1473         return -1;
1474 }
1475
1476 /*
1477  * This verifies that the buffer is in proper utf8 format.
1478  *
1479  * If it isn't, it assumes any non-utf8 characters are Latin1,
1480  * and does the conversion.
1481  */
1482 static int verify_utf8(struct strbuf *buf)
1483 {
1484         int ok = 1;
1485         long pos = 0;
1486
1487         for (;;) {
1488                 int bad;
1489                 unsigned char c;
1490                 unsigned char replace[2];
1491
1492                 bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1493                 if (bad < 0)
1494                         return ok;
1495                 pos += bad;
1496                 ok = 0;
1497                 c = buf->buf[pos];
1498                 strbuf_remove(buf, pos, 1);
1499
1500                 /* We know 'c' must be in the range 128-255 */
1501                 replace[0] = 0xc0 + (c >> 6);
1502                 replace[1] = 0x80 + (c & 0x3f);
1503                 strbuf_insert(buf, pos, replace, 2);
1504                 pos += 2;
1505         }
1506 }
1507
1508 static const char commit_utf8_warn[] =
1509 "Warning: commit message did not conform to UTF-8.\n"
1510 "You may want to amend it after fixing the message, or set the config\n"
1511 "variable i18n.commitencoding to the encoding your project uses.\n";
1512
1513 int commit_tree_extended(const char *msg, size_t msg_len,
1514                          const unsigned char *tree,
1515                          struct commit_list *parents, unsigned char *ret,
1516                          const char *author, const char *sign_commit,
1517                          struct commit_extra_header *extra)
1518 {
1519         int result;
1520         int encoding_is_utf8;
1521         struct strbuf buffer;
1522
1523         assert_sha1_type(tree, OBJ_TREE);
1524
1525         if (memchr(msg, '\0', msg_len))
1526                 return error("a NUL byte in commit log message not allowed.");
1527
1528         /* Not having i18n.commitencoding is the same as having utf-8 */
1529         encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1530
1531         strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1532         strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1533
1534         /*
1535          * NOTE! This ordering means that the same exact tree merged with a
1536          * different order of parents will be a _different_ changeset even
1537          * if everything else stays the same.
1538          */
1539         while (parents) {
1540                 struct commit_list *next = parents->next;
1541                 struct commit *parent = parents->item;
1542
1543                 strbuf_addf(&buffer, "parent %s\n",
1544                             sha1_to_hex(parent->object.sha1));
1545                 free(parents);
1546                 parents = next;
1547         }
1548
1549         /* Person/date information */
1550         if (!author)
1551                 author = git_author_info(IDENT_STRICT);
1552         strbuf_addf(&buffer, "author %s\n", author);
1553         strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1554         if (!encoding_is_utf8)
1555                 strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1556
1557         while (extra) {
1558                 add_extra_header(&buffer, extra);
1559                 extra = extra->next;
1560         }
1561         strbuf_addch(&buffer, '\n');
1562
1563         /* And add the comment */
1564         strbuf_add(&buffer, msg, msg_len);
1565
1566         /* And check the encoding */
1567         if (encoding_is_utf8 && !verify_utf8(&buffer))
1568                 fprintf(stderr, commit_utf8_warn);
1569
1570         if (sign_commit && do_sign_commit(&buffer, sign_commit))
1571                 return -1;
1572
1573         result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1574         strbuf_release(&buffer);
1575         return result;
1576 }
1577
1578 struct commit *get_merge_parent(const char *name)
1579 {
1580         struct object *obj;
1581         struct commit *commit;
1582         unsigned char sha1[20];
1583         if (get_sha1(name, sha1))
1584                 return NULL;
1585         obj = parse_object(sha1);
1586         commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1587         if (commit && !commit->util) {
1588                 struct merge_remote_desc *desc;
1589                 desc = xmalloc(sizeof(*desc));
1590                 desc->obj = obj;
1591                 desc->name = strdup(name);
1592                 commit->util = desc;
1593         }
1594         return commit;
1595 }
1596
1597 /*
1598  * Append a commit to the end of the commit_list.
1599  *
1600  * next starts by pointing to the variable that holds the head of an
1601  * empty commit_list, and is updated to point to the "next" field of
1602  * the last item on the list as new commits are appended.
1603  *
1604  * Usage example:
1605  *
1606  *     struct commit_list *list;
1607  *     struct commit_list **next = &list;
1608  *
1609  *     next = commit_list_append(c1, next);
1610  *     next = commit_list_append(c2, next);
1611  *     assert(commit_list_count(list) == 2);
1612  *     return list;
1613  */
1614 struct commit_list **commit_list_append(struct commit *commit,
1615                                         struct commit_list **next)
1616 {
1617         struct commit_list *new = xmalloc(sizeof(struct commit_list));
1618         new->item = commit;
1619         *next = new;
1620         new->next = NULL;
1621         return &new->next;
1622 }
1623
1624 void print_commit_list(struct commit_list *list,
1625                        const char *format_cur,
1626                        const char *format_last)
1627 {
1628         for ( ; list; list = list->next) {
1629                 const char *format = list->next ? format_cur : format_last;
1630                 printf(format, sha1_to_hex(list->item->object.sha1));
1631         }
1632 }