commit.c

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