commit.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4
   5 int save_commit_buffer = 1;
   6
   7 struct sort_node
   8 {
   9         /*
  10          * the number of children of the associated commit
  11          * that also occur in the list being sorted.
  12          */
  13         unsigned int indegree;
  14
  15         /*
  16          * reference to original list item that we will re-use
  17          * on output.
  18          */
  19         struct commit_list * list_item;
  20
  21 };
  22
  23 const char *commit_type = "commit";
  24
  25 struct cmt_fmt_map {
  26         const char *n;
  27         size_t cmp_len;
  28         enum cmit_fmt v;
  29 } cmt_fmts[] = {
  30         { "raw",        1,      CMIT_FMT_RAW },
  31         { "medium",     1,      CMIT_FMT_MEDIUM },
  32         { "short",      1,      CMIT_FMT_SHORT },
  33         { "email",      1,      CMIT_FMT_EMAIL },
  34         { "full",       5,      CMIT_FMT_FULL },
  35         { "fuller",     5,      CMIT_FMT_FULLER },
  36         { "oneline",    1,      CMIT_FMT_ONELINE },
  37 };
  38
  39 enum cmit_fmt get_commit_format(const char *arg)
  40 {
  41         int i;
  42
  43         if (!arg || !*arg)
  44                 return CMIT_FMT_DEFAULT;
  45         if (*arg == '=')
  46                 arg++;
  47         for (i = 0; i < ARRAY_SIZE(cmt_fmts); i++) {
  48                 if (!strncmp(arg, cmt_fmts[i].n, cmt_fmts[i].cmp_len))
  49                         return cmt_fmts[i].v;
  50         }
  51
  52         die("invalid --pretty format: %s", arg);
  53 }
  54
  55 static struct commit *check_commit(struct object *obj,
  56                                    const unsigned char *sha1,
  57                                    int quiet)
  58 {
  59         if (obj->type != commit_type) {
  60                 if (!quiet)
  61                         error("Object %s is a %s, not a commit",
  62                               sha1_to_hex(sha1), obj->type);
  63                 return NULL;
  64         }
  65         return (struct commit *) obj;
  66 }
  67
  68 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  69                                               int quiet)
  70 {
  71         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  72
  73         if (!obj)
  74                 return NULL;
  75         return check_commit(obj, sha1, quiet);
  76 }
  77
  78 struct commit *lookup_commit_reference(const unsigned char *sha1)
  79 {
  80         return lookup_commit_reference_gently(sha1, 0);
  81 }
  82
  83 struct commit *lookup_commit(const unsigned char *sha1)
  84 {
  85         struct object *obj = lookup_object(sha1);
  86         if (!obj) {
  87                 struct commit *ret = xcalloc(1, sizeof(struct commit));
  88                 created_object(sha1, &ret->object);
  89                 ret->object.type = commit_type;
  90                 return ret;
  91         }
  92         if (!obj->type)
  93                 obj->type = commit_type;
  94         return check_commit(obj, sha1, 0);
  95 }
  96
  97 static unsigned long parse_commit_date(const char *buf)
  98 {
  99         unsigned long date;
 100
 101         if (memcmp(buf, "author", 6))
 102                 return 0;
 103         while (*buf++ != '\n')
 104                 /* nada */;
 105         if (memcmp(buf, "committer", 9))
 106                 return 0;
 107         while (*buf++ != '>')
 108                 /* nada */;
 109         date = strtoul(buf, NULL, 10);
 110         if (date == ULONG_MAX)
 111                 date = 0;
 112         return date;
 113 }
 114
 115 static struct commit_graft **commit_graft;
 116 static int commit_graft_alloc, commit_graft_nr;
 117
 118 static int commit_graft_pos(const unsigned char *sha1)
 119 {
 120         int lo, hi;
 121         lo = 0;
 122         hi = commit_graft_nr;
 123         while (lo < hi) {
 124                 int mi = (lo + hi) / 2;
 125                 struct commit_graft *graft = commit_graft[mi];
 126                 int cmp = memcmp(sha1, graft->sha1, 20);
 127                 if (!cmp)
 128                         return mi;
 129                 if (cmp < 0)
 130                         hi = mi;
 131                 else
 132                         lo = mi + 1;
 133         }
 134         return -lo - 1;
 135 }
 136
 137 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 138 {
 139         int pos = commit_graft_pos(graft->sha1);
 140
 141         if (0 <= pos) {
 142                 if (ignore_dups)
 143                         free(graft);
 144                 else {
 145                         free(commit_graft[pos]);
 146                         commit_graft[pos] = graft;
 147                 }
 148                 return 1;
 149         }
 150         pos = -pos - 1;
 151         if (commit_graft_alloc <= ++commit_graft_nr) {
 152                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 153                 commit_graft = xrealloc(commit_graft,
 154                                         sizeof(*commit_graft) *
 155                                         commit_graft_alloc);
 156         }
 157         if (pos < commit_graft_nr)
 158                 memmove(commit_graft + pos + 1,
 159                         commit_graft + pos,
 160                         (commit_graft_nr - pos - 1) *
 161                         sizeof(*commit_graft));
 162         commit_graft[pos] = graft;
 163         return 0;
 164 }
 165
 166 struct commit_graft *read_graft_line(char *buf, int len)
 167 {
 168         /* The format is just "Commit Parent1 Parent2 ...\n" */
 169         int i;
 170         struct commit_graft *graft = NULL;
 171
 172         if (buf[len-1] == '\n')
 173                 buf[--len] = 0;
 174         if (buf[0] == '#' || buf[0] == '\0')
 175                 return NULL;
 176         if ((len + 1) % 41) {
 177         bad_graft_data:
 178                 error("bad graft data: %s", buf);
 179                 free(graft);
 180                 return NULL;
 181         }
 182         i = (len + 1) / 41 - 1;
 183         graft = xmalloc(sizeof(*graft) + 20 * i);
 184         graft->nr_parent = i;
 185         if (get_sha1_hex(buf, graft->sha1))
 186                 goto bad_graft_data;
 187         for (i = 40; i < len; i += 41) {
 188                 if (buf[i] != ' ')
 189                         goto bad_graft_data;
 190                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 191                         goto bad_graft_data;
 192         }
 193         return graft;
 194 }
 195
 196 int read_graft_file(const char *graft_file)
 197 {
 198         FILE *fp = fopen(graft_file, "r");
 199         char buf[1024];
 200         if (!fp)
 201                 return -1;
 202         while (fgets(buf, sizeof(buf), fp)) {
 203                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 204                 int len = strlen(buf);
 205                 struct commit_graft *graft = read_graft_line(buf, len);
 206                 if (!graft)
 207                         continue;
 208                 if (register_commit_graft(graft, 1))
 209                         error("duplicate graft data: %s", buf);
 210         }
 211         fclose(fp);
 212         return 0;
 213 }
 214
 215 static void prepare_commit_graft(void)
 216 {
 217         static int commit_graft_prepared;
 218         char *graft_file;
 219
 220         if (commit_graft_prepared)
 221                 return;
 222         graft_file = get_graft_file();
 223         read_graft_file(graft_file);
 224         commit_graft_prepared = 1;
 225 }
 226
 227 static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 228 {
 229         int pos;
 230         prepare_commit_graft();
 231         pos = commit_graft_pos(sha1);
 232         if (pos < 0)
 233                 return NULL;
 234         return commit_graft[pos];
 235 }
 236
 237 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 238 {
 239         char *bufptr = buffer;
 240         unsigned char parent[20];
 241         struct commit_list **pptr;
 242         struct commit_graft *graft;
 243         unsigned n_refs = 0;
 244
 245         if (item->object.parsed)
 246                 return 0;
 247         item->object.parsed = 1;
 248         if (memcmp(bufptr, "tree ", 5))
 249                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 250         if (get_sha1_hex(bufptr + 5, parent) < 0)
 251                 return error("bad tree pointer in commit %s",
 252                              sha1_to_hex(item->object.sha1));
 253         item->tree = lookup_tree(parent);
 254         if (item->tree)
 255                 n_refs++;
 256         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 257         pptr = &item->parents;
 258
 259         graft = lookup_commit_graft(item->object.sha1);
 260         while (!memcmp(bufptr, "parent ", 7)) {
 261                 struct commit *new_parent;
 262
 263                 if (get_sha1_hex(bufptr + 7, parent) || bufptr[47] != '\n')
 264                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 265                 bufptr += 48;
 266                 if (graft)
 267                         continue;
 268                 new_parent = lookup_commit(parent);
 269                 if (new_parent) {
 270                         pptr = &commit_list_insert(new_parent, pptr)->next;
 271                         n_refs++;
 272                 }
 273         }
 274         if (graft) {
 275                 int i;
 276                 struct commit *new_parent;
 277                 for (i = 0; i < graft->nr_parent; i++) {
 278                         new_parent = lookup_commit(graft->parent[i]);
 279                         if (!new_parent)
 280                                 continue;
 281                         pptr = &commit_list_insert(new_parent, pptr)->next;
 282                         n_refs++;
 283                 }
 284         }
 285         item->date = parse_commit_date(bufptr);
 286
 287         if (track_object_refs) {
 288                 unsigned i = 0;
 289                 struct commit_list *p;
 290                 struct object_refs *refs = alloc_object_refs(n_refs);
 291                 if (item->tree)
 292                         refs->ref[i++] = &item->tree->object;
 293                 for (p = item->parents; p; p = p->next)
 294                         refs->ref[i++] = &p->item->object;
 295                 set_object_refs(&item->object, refs);
 296         }
 297
 298         return 0;
 299 }
 300
 301 int parse_commit(struct commit *item)
 302 {
 303         char type[20];
 304         void *buffer;
 305         unsigned long size;
 306         int ret;
 307
 308         if (item->object.parsed)
 309                 return 0;
 310         buffer = read_sha1_file(item->object.sha1, type, &size);
 311         if (!buffer)
 312                 return error("Could not read %s",
 313                              sha1_to_hex(item->object.sha1));
 314         if (strcmp(type, commit_type)) {
 315                 free(buffer);
 316                 return error("Object %s not a commit",
 317                              sha1_to_hex(item->object.sha1));
 318         }
 319         ret = parse_commit_buffer(item, buffer, size);
 320         if (save_commit_buffer && !ret) {
 321                 item->buffer = buffer;
 322                 return 0;
 323         }
 324         free(buffer);
 325         return ret;
 326 }
 327
 328 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 329 {
 330         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 331         new_list->item = item;
 332         new_list->next = *list_p;
 333         *list_p = new_list;
 334         return new_list;
 335 }
 336
 337 void free_commit_list(struct commit_list *list)
 338 {
 339         while (list) {
 340                 struct commit_list *temp = list;
 341                 list = temp->next;
 342                 free(temp);
 343         }
 344 }
 345
 346 struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 347 {
 348         struct commit_list **pp = list;
 349         struct commit_list *p;
 350         while ((p = *pp) != NULL) {
 351                 if (p->item->date < item->date) {
 352                         break;
 353                 }
 354                 pp = &p->next;
 355         }
 356         return commit_list_insert(item, pp);
 357 }
 358
 359
 360 void sort_by_date(struct commit_list **list)
 361 {
 362         struct commit_list *ret = NULL;
 363         while (*list) {
 364                 insert_by_date((*list)->item, &ret);
 365                 *list = (*list)->next;
 366         }
 367         *list = ret;
 368 }
 369
 370 struct commit *pop_most_recent_commit(struct commit_list **list,
 371                                       unsigned int mark)
 372 {
 373         struct commit *ret = (*list)->item;
 374         struct commit_list *parents = ret->parents;
 375         struct commit_list *old = *list;
 376
 377         *list = (*list)->next;
 378         free(old);
 379
 380         while (parents) {
 381                 struct commit *commit = parents->item;
 382                 parse_commit(commit);
 383                 if (!(commit->object.flags & mark)) {
 384                         commit->object.flags |= mark;
 385                         insert_by_date(commit, list);
 386                 }
 387                 parents = parents->next;
 388         }
 389         return ret;
 390 }
 391
 392 void clear_commit_marks(struct commit *commit, unsigned int mark)
 393 {
 394         struct commit_list *parents;
 395
 396         parents = commit->parents;
 397         commit->object.flags &= ~mark;
 398         while (parents) {
 399                 struct commit *parent = parents->item;
 400                 if (parent && parent->object.parsed &&
 401                     (parent->object.flags & mark))
 402                         clear_commit_marks(parent, mark);
 403                 parents = parents->next;
 404         }
 405 }
 406
 407 /*
 408  * Generic support for pretty-printing the header
 409  */
 410 static int get_one_line(const char *msg, unsigned long len)
 411 {
 412         int ret = 0;
 413
 414         while (len--) {
 415                 char c = *msg++;
 416                 if (!c)
 417                         break;
 418                 ret++;
 419                 if (c == '\n')
 420                         break;
 421         }
 422         return ret;
 423 }
 424
 425 static int is_rfc2047_special(char ch)
 426 {
 427         return ((ch & 0x80) || (ch == '=') || (ch == '?') || (ch == '_'));
 428 }
 429
 430 static int add_rfc2047(char *buf, const char *line, int len)
 431 {
 432         char *bp = buf;
 433         int i, needquote;
 434         static const char q_utf8[] = "=?utf-8?q?";
 435
 436         for (i = needquote = 0; !needquote && i < len; i++) {
 437                 unsigned ch = line[i];
 438                 if (ch & 0x80)
 439                         needquote++;
 440                 if ((i + 1 < len) &&
 441                     (ch == '=' && line[i+1] == '?'))
 442                         needquote++;
 443         }
 444         if (!needquote)
 445                 return sprintf(buf, "%.*s", len, line);
 446
 447         memcpy(bp, q_utf8, sizeof(q_utf8)-1);
 448         bp += sizeof(q_utf8)-1;
 449         for (i = 0; i < len; i++) {
 450                 unsigned ch = line[i];
 451                 if (is_rfc2047_special(ch)) {
 452                         sprintf(bp, "=%02X", ch);
 453                         bp += 3;
 454                 }
 455                 else if (ch == ' ')
 456                         *bp++ = '_';
 457                 else
 458                         *bp++ = ch;
 459         }
 460         memcpy(bp, "?=", 2);
 461         bp += 2;
 462         return bp - buf;
 463 }
 464
 465 static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
 466 {
 467         char *date;
 468         int namelen;
 469         unsigned long time;
 470         int tz, ret;
 471         const char *filler = "    ";
 472
 473         if (fmt == CMIT_FMT_ONELINE)
 474                 return 0;
 475         date = strchr(line, '>');
 476         if (!date)
 477                 return 0;
 478         namelen = ++date - line;
 479         time = strtoul(date, &date, 10);
 480         tz = strtol(date, NULL, 10);
 481
 482         if (fmt == CMIT_FMT_EMAIL) {
 483                 char *name_tail = strchr(line, '<');
 484                 int display_name_length;
 485                 if (!name_tail)
 486                         return 0;
 487                 while (line < name_tail && isspace(name_tail[-1]))
 488                         name_tail--;
 489                 display_name_length = name_tail - line;
 490                 filler = "";
 491                 strcpy(buf, "From: ");
 492                 ret = strlen(buf);
 493                 ret += add_rfc2047(buf + ret, line, display_name_length);
 494                 memcpy(buf + ret, name_tail, namelen - display_name_length);
 495                 ret += namelen - display_name_length;
 496                 buf[ret++] = '\n';
 497         }
 498         else {
 499                 ret = sprintf(buf, "%s: %.*s%.*s\n", what,
 500                               (fmt == CMIT_FMT_FULLER) ? 4 : 0,
 501                               filler, namelen, line);
 502         }
 503         switch (fmt) {
 504         case CMIT_FMT_MEDIUM:
 505                 ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
 506                 break;
 507         case CMIT_FMT_EMAIL:
 508                 ret += sprintf(buf + ret, "Date: %s\n",
 509                                show_rfc2822_date(time, tz));
 510                 break;
 511         case CMIT_FMT_FULLER:
 512                 ret += sprintf(buf + ret, "%sDate: %s\n", what, show_date(time, tz));
 513                 break;
 514         default:
 515                 /* notin' */
 516                 break;
 517         }
 518         return ret;
 519 }
 520
 521 static int is_empty_line(const char *line, int *len_p)
 522 {
 523         int len = *len_p;
 524         while (len && isspace(line[len-1]))
 525                 len--;
 526         *len_p = len;
 527         return !len;
 528 }
 529
 530 static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 531 {
 532         struct commit_list *parent = commit->parents;
 533         int offset;
 534
 535         if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
 536             !parent || !parent->next)
 537                 return 0;
 538
 539         offset = sprintf(buf, "Merge:");
 540
 541         while (parent) {
 542                 struct commit *p = parent->item;
 543                 const char *hex = abbrev
 544                         ? find_unique_abbrev(p->object.sha1, abbrev)
 545                         : sha1_to_hex(p->object.sha1);
 546                 char *dots = (abbrev && strlen(hex) != 40) ? "..." : "";
 547                 parent = parent->next;
 548
 549                 offset += sprintf(buf + offset, " %s%s", hex, dots);
 550         }
 551         buf[offset++] = '\n';
 552         return offset;
 553 }
 554
 555 unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit, unsigned long len, char *buf, unsigned long space, int abbrev, const char *subject, const char *after_subject)
 556 {
 557         int hdr = 1, body = 0;
 558         unsigned long offset = 0;
 559         int indent = 4;
 560         int parents_shown = 0;
 561         const char *msg = commit->buffer;
 562         int plain_non_ascii = 0;
 563
 564         if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
 565                 indent = 0;
 566
 567         /* After-subject is used to pass in Content-Type: multipart
 568          * MIME header; in that case we do not have to do the
 569          * plaintext content type even if the commit message has
 570          * non 7-bit ASCII character.  Otherwise, check if we need
 571          * to say this is not a 7-bit ASCII.
 572          */
 573         if (fmt == CMIT_FMT_EMAIL && !after_subject) {
 574                 int i;
 575                 for (i = 0; !plain_non_ascii && msg[i] && i < len; i++)
 576                         if (msg[i] & 0x80)
 577                                 plain_non_ascii = 1;
 578         }
 579
 580         for (;;) {
 581                 const char *line = msg;
 582                 int linelen = get_one_line(msg, len);
 583
 584                 if (!linelen)
 585                         break;
 586
 587                 /*
 588                  * We want some slop for indentation and a possible
 589                  * final "...". Thus the "+ 20".
 590                  */
 591                 if (offset + linelen + 20 > space) {
 592                         memcpy(buf + offset, "    ...\n", 8);
 593                         offset += 8;
 594                         break;
 595                 }
 596
 597                 msg += linelen;
 598                 len -= linelen;
 599                 if (hdr) {
 600                         if (linelen == 1) {
 601                                 hdr = 0;
 602                                 if ((fmt != CMIT_FMT_ONELINE) && !subject)
 603                                         buf[offset++] = '\n';
 604                                 continue;
 605                         }
 606                         if (fmt == CMIT_FMT_RAW) {
 607                                 memcpy(buf + offset, line, linelen);
 608                                 offset += linelen;
 609                                 continue;
 610                         }
 611                         if (!memcmp(line, "parent ", 7)) {
 612                                 if (linelen != 48)
 613                                         die("bad parent line in commit");
 614                                 continue;
 615                         }
 616
 617                         if (!parents_shown) {
 618                                 offset += add_merge_info(fmt, buf + offset,
 619                                                          commit, abbrev);
 620                                 parents_shown = 1;
 621                                 continue;
 622                         }
 623                         /*
 624                          * MEDIUM == DEFAULT shows only author with dates.
 625                          * FULL shows both authors but not dates.
 626                          * FULLER shows both authors and dates.
 627                          */
 628                         if (!memcmp(line, "author ", 7))
 629                                 offset += add_user_info("Author", fmt,
 630                                                         buf + offset,
 631                                                         line + 7);
 632                         if (!memcmp(line, "committer ", 10) &&
 633                             (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
 634                                 offset += add_user_info("Commit", fmt,
 635                                                         buf + offset,
 636                                                         line + 10);
 637                         continue;
 638                 }
 639
 640                 if (is_empty_line(line, &linelen)) {
 641                         if (!body)
 642                                 continue;
 643                         if (subject)
 644                                 continue;
 645                         if (fmt == CMIT_FMT_SHORT)
 646                                 break;
 647                 } else {
 648                         body = 1;
 649                 }
 650
 651                 if (subject) {
 652                         int slen = strlen(subject);
 653                         memcpy(buf + offset, subject, slen);
 654                         offset += slen;
 655                         offset += add_rfc2047(buf + offset, line, linelen);
 656                 }
 657                 else {
 658                         memset(buf + offset, ' ', indent);
 659                         memcpy(buf + offset + indent, line, linelen);
 660                         offset += linelen + indent;
 661                 }
 662                 buf[offset++] = '\n';
 663                 if (fmt == CMIT_FMT_ONELINE)
 664                         break;
 665                 if (subject && plain_non_ascii) {
 666                         static const char header[] =
 667                                 "Content-Type: text/plain; charset=UTF-8\n"
 668                                 "Content-Transfer-Encoding: 8bit\n";
 669                         memcpy(buf + offset, header, sizeof(header)-1);
 670                         offset += sizeof(header)-1;
 671                 }
 672                 if (after_subject) {
 673                         int slen = strlen(after_subject);
 674                         if (slen > space - offset - 1)
 675                                 slen = space - offset - 1;
 676                         memcpy(buf + offset, after_subject, slen);
 677                         offset += slen;
 678                         after_subject = NULL;
 679                 }
 680                 subject = NULL;
 681         }
 682         while (offset && isspace(buf[offset-1]))
 683                 offset--;
 684         /* Make sure there is an EOLN for the non-oneline case */
 685         if (fmt != CMIT_FMT_ONELINE)
 686                 buf[offset++] = '\n';
 687         buf[offset] = '\0';
 688         return offset;
 689 }
 690
 691 struct commit *pop_commit(struct commit_list **stack)
 692 {
 693         struct commit_list *top = *stack;
 694         struct commit *item = top ? top->item : NULL;
 695
 696         if (top) {
 697                 *stack = top->next;
 698                 free(top);
 699         }
 700         return item;
 701 }
 702
 703 int count_parents(struct commit * commit)
 704 {
 705         int count = 0;
 706         struct commit_list * parents = commit->parents;
 707         for (count=0;parents; parents=parents->next,count++)
 708           ;
 709         return count;
 710 }
 711
 712 void topo_sort_default_setter(struct commit *c, void *data)
 713 {
 714         c->object.util = data;
 715 }
 716
 717 void *topo_sort_default_getter(struct commit *c)
 718 {
 719         return c->object.util;
 720 }
 721
 722 /*
 723  * Performs an in-place topological sort on the list supplied.
 724  */
 725 void sort_in_topological_order(struct commit_list ** list, int lifo)
 726 {
 727         sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
 728                                      topo_sort_default_getter);
 729 }
 730
 731 void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 732                                   topo_sort_set_fn_t setter,
 733                                   topo_sort_get_fn_t getter)
 734 {
 735         struct commit_list * next = *list;
 736         struct commit_list * work = NULL, **insert;
 737         struct commit_list ** pptr = list;
 738         struct sort_node * nodes;
 739         struct sort_node * next_nodes;
 740         int count = 0;
 741
 742         /* determine the size of the list */
 743         while (next) {
 744                 next = next->next;
 745                 count++;
 746         }
 747
 748         if (!count)
 749                 return;
 750         /* allocate an array to help sort the list */
 751         nodes = xcalloc(count, sizeof(*nodes));
 752         /* link the list to the array */
 753         next_nodes = nodes;
 754         next=*list;
 755         while (next) {
 756                 next_nodes->list_item = next;
 757                 setter(next->item, next_nodes);
 758                 next_nodes++;
 759                 next = next->next;
 760         }
 761         /* update the indegree */
 762         next=*list;
 763         while (next) {
 764                 struct commit_list * parents = next->item->parents;
 765                 while (parents) {
 766                         struct commit * parent=parents->item;
 767                         struct sort_node * pn = (struct sort_node *) getter(parent);
 768
 769                         if (pn)
 770                                 pn->indegree++;
 771                         parents=parents->next;
 772                 }
 773                 next=next->next;
 774         }
 775         /*
 776          * find the tips
 777          *
 778          * tips are nodes not reachable from any other node in the list
 779          *
 780          * the tips serve as a starting set for the work queue.
 781          */
 782         next=*list;
 783         insert = &work;
 784         while (next) {
 785                 struct sort_node * node = (struct sort_node *) getter(next->item);
 786
 787                 if (node->indegree == 0) {
 788                         insert = &commit_list_insert(next->item, insert)->next;
 789                 }
 790                 next=next->next;
 791         }
 792
 793         /* process the list in topological order */
 794         if (!lifo)
 795                 sort_by_date(&work);
 796         while (work) {
 797                 struct commit * work_item = pop_commit(&work);
 798                 struct sort_node * work_node = (struct sort_node *) getter(work_item);
 799                 struct commit_list * parents = work_item->parents;
 800
 801                 while (parents) {
 802                         struct commit * parent=parents->item;
 803                         struct sort_node * pn = (struct sort_node *) getter(parent);
 804
 805                         if (pn) {
 806                                 /*
 807                                  * parents are only enqueued for emission
 808                                  * when all their children have been emitted thereby
 809                                  * guaranteeing topological order.
 810                                  */
 811                                 pn->indegree--;
 812                                 if (!pn->indegree) {
 813                                         if (!lifo)
 814                                                 insert_by_date(parent, &work);
 815                                         else
 816                                                 commit_list_insert(parent, &work);
 817                                 }
 818                         }
 819                         parents=parents->next;
 820                 }
 821                 /*
 822                  * work_item is a commit all of whose children
 823                  * have already been emitted. we can emit it now.
 824                  */
 825                 *pptr = work_node->list_item;
 826                 pptr = &(*pptr)->next;
 827                 *pptr = NULL;
 828                 setter(work_item, NULL);
 829         }
 830         free(nodes);
 831 }