commit.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "pkt-line.h"
   5
   6 int save_commit_buffer = 1;
   7
   8 struct sort_node
   9 {
  10         /*
  11          * the number of children of the associated commit
  12          * that also occur in the list being sorted.
  13          */
  14         unsigned int indegree;
  15
  16         /*
  17          * reference to original list item that we will re-use
  18          * on output.
  19          */
  20         struct commit_list * list_item;
  21
  22 };
  23
  24 const char *commit_type = "commit";
  25
  26 struct cmt_fmt_map {
  27         const char *n;
  28         size_t cmp_len;
  29         enum cmit_fmt v;
  30 } cmt_fmts[] = {
  31         { "raw",        1,      CMIT_FMT_RAW },
  32         { "medium",     1,      CMIT_FMT_MEDIUM },
  33         { "short",      1,      CMIT_FMT_SHORT },
  34         { "email",      1,      CMIT_FMT_EMAIL },
  35         { "full",       5,      CMIT_FMT_FULL },
  36         { "fuller",     5,      CMIT_FMT_FULLER },
  37         { "oneline",    1,      CMIT_FMT_ONELINE },
  38 };
  39
  40 enum cmit_fmt get_commit_format(const char *arg)
  41 {
  42         int i;
  43
  44         if (!arg || !*arg)
  45                 return CMIT_FMT_DEFAULT;
  46         if (*arg == '=')
  47                 arg++;
  48         for (i = 0; i < ARRAY_SIZE(cmt_fmts); i++) {
  49                 if (!strncmp(arg, cmt_fmts[i].n, cmt_fmts[i].cmp_len))
  50                         return cmt_fmts[i].v;
  51         }
  52
  53         die("invalid --pretty format: %s", arg);
  54 }
  55
  56 static struct commit *check_commit(struct object *obj,
  57                                    const unsigned char *sha1,
  58                                    int quiet)
  59 {
  60         if (obj->type != OBJ_COMMIT) {
  61                 if (!quiet)
  62                         error("Object %s is a %s, not a commit",
  63                               sha1_to_hex(sha1), typename(obj->type));
  64                 return NULL;
  65         }
  66         return (struct commit *) obj;
  67 }
  68
  69 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  70                                               int quiet)
  71 {
  72         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  73
  74         if (!obj)
  75                 return NULL;
  76         return check_commit(obj, sha1, quiet);
  77 }
  78
  79 struct commit *lookup_commit_reference(const unsigned char *sha1)
  80 {
  81         return lookup_commit_reference_gently(sha1, 0);
  82 }
  83
  84 struct commit *lookup_commit(const unsigned char *sha1)
  85 {
  86         struct object *obj = lookup_object(sha1);
  87         if (!obj) {
  88                 struct commit *ret = alloc_commit_node();
  89                 created_object(sha1, &ret->object);
  90                 ret->object.type = OBJ_COMMIT;
  91                 return ret;
  92         }
  93         if (!obj->type)
  94                 obj->type = OBJ_COMMIT;
  95         return check_commit(obj, sha1, 0);
  96 }
  97
  98 static unsigned long parse_commit_date(const char *buf)
  99 {
 100         unsigned long date;
 101
 102         if (memcmp(buf, "author", 6))
 103                 return 0;
 104         while (*buf++ != '\n')
 105                 /* nada */;
 106         if (memcmp(buf, "committer", 9))
 107                 return 0;
 108         while (*buf++ != '>')
 109                 /* nada */;
 110         date = strtoul(buf, NULL, 10);
 111         if (date == ULONG_MAX)
 112                 date = 0;
 113         return date;
 114 }
 115
 116 static struct commit_graft **commit_graft;
 117 static int commit_graft_alloc, commit_graft_nr;
 118
 119 static int commit_graft_pos(const unsigned char *sha1)
 120 {
 121         int lo, hi;
 122         lo = 0;
 123         hi = commit_graft_nr;
 124         while (lo < hi) {
 125                 int mi = (lo + hi) / 2;
 126                 struct commit_graft *graft = commit_graft[mi];
 127                 int cmp = hashcmp(sha1, graft->sha1);
 128                 if (!cmp)
 129                         return mi;
 130                 if (cmp < 0)
 131                         hi = mi;
 132                 else
 133                         lo = mi + 1;
 134         }
 135         return -lo - 1;
 136 }
 137
 138 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 139 {
 140         int pos = commit_graft_pos(graft->sha1);
 141
 142         if (0 <= pos) {
 143                 if (ignore_dups)
 144                         free(graft);
 145                 else {
 146                         free(commit_graft[pos]);
 147                         commit_graft[pos] = graft;
 148                 }
 149                 return 1;
 150         }
 151         pos = -pos - 1;
 152         if (commit_graft_alloc <= ++commit_graft_nr) {
 153                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 154                 commit_graft = xrealloc(commit_graft,
 155                                         sizeof(*commit_graft) *
 156                                         commit_graft_alloc);
 157         }
 158         if (pos < commit_graft_nr)
 159                 memmove(commit_graft + pos + 1,
 160                         commit_graft + pos,
 161                         (commit_graft_nr - pos - 1) *
 162                         sizeof(*commit_graft));
 163         commit_graft[pos] = graft;
 164         return 0;
 165 }
 166
 167 struct commit_graft *read_graft_line(char *buf, int len)
 168 {
 169         /* The format is just "Commit Parent1 Parent2 ...\n" */
 170         int i;
 171         struct commit_graft *graft = NULL;
 172
 173         if (buf[len-1] == '\n')
 174                 buf[--len] = 0;
 175         if (buf[0] == '#' || buf[0] == '\0')
 176                 return NULL;
 177         if ((len + 1) % 41) {
 178         bad_graft_data:
 179                 error("bad graft data: %s", buf);
 180                 free(graft);
 181                 return NULL;
 182         }
 183         i = (len + 1) / 41 - 1;
 184         graft = xmalloc(sizeof(*graft) + 20 * i);
 185         graft->nr_parent = i;
 186         if (get_sha1_hex(buf, graft->sha1))
 187                 goto bad_graft_data;
 188         for (i = 40; i < len; i += 41) {
 189                 if (buf[i] != ' ')
 190                         goto bad_graft_data;
 191                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 192                         goto bad_graft_data;
 193         }
 194         return graft;
 195 }
 196
 197 int read_graft_file(const char *graft_file)
 198 {
 199         FILE *fp = fopen(graft_file, "r");
 200         char buf[1024];
 201         if (!fp)
 202                 return -1;
 203         while (fgets(buf, sizeof(buf), fp)) {
 204                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 205                 int len = strlen(buf);
 206                 struct commit_graft *graft = read_graft_line(buf, len);
 207                 if (!graft)
 208                         continue;
 209                 if (register_commit_graft(graft, 1))
 210                         error("duplicate graft data: %s", buf);
 211         }
 212         fclose(fp);
 213         return 0;
 214 }
 215
 216 static void prepare_commit_graft(void)
 217 {
 218         static int commit_graft_prepared;
 219         char *graft_file;
 220
 221         if (commit_graft_prepared)
 222                 return;
 223         graft_file = get_graft_file();
 224         read_graft_file(graft_file);
 225         /* make sure shallows are read */
 226         is_repository_shallow();
 227         commit_graft_prepared = 1;
 228 }
 229
 230 static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 231 {
 232         int pos;
 233         prepare_commit_graft();
 234         pos = commit_graft_pos(sha1);
 235         if (pos < 0)
 236                 return NULL;
 237         return commit_graft[pos];
 238 }
 239
 240 int write_shallow_commits(int fd, int use_pack_protocol)
 241 {
 242         int i, count = 0;
 243         for (i = 0; i < commit_graft_nr; i++)
 244                 if (commit_graft[i]->nr_parent < 0) {
 245                         const char *hex =
 246                                 sha1_to_hex(commit_graft[i]->sha1);
 247                         count++;
 248                         if (use_pack_protocol)
 249                                 packet_write(fd, "shallow %s", hex);
 250                         else {
 251                                 write(fd, hex,  40);
 252                                 write(fd, "\n", 1);
 253                         }
 254                 }
 255         return count;
 256 }
 257
 258 int unregister_shallow(const unsigned char *sha1)
 259 {
 260         int pos = commit_graft_pos(sha1);
 261         if (pos < 0)
 262                 return -1;
 263         if (pos + 1 < commit_graft_nr)
 264                 memcpy(commit_graft + pos, commit_graft + pos + 1,
 265                                 sizeof(struct commit_graft *)
 266                                 * (commit_graft_nr - pos - 1));
 267         commit_graft_nr--;
 268         return 0;
 269 }
 270
 271 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 272 {
 273         char *tail = buffer;
 274         char *bufptr = buffer;
 275         unsigned char parent[20];
 276         struct commit_list **pptr;
 277         struct commit_graft *graft;
 278         unsigned n_refs = 0;
 279
 280         if (item->object.parsed)
 281                 return 0;
 282         item->object.parsed = 1;
 283         tail += size;
 284         if (tail <= bufptr + 5 || memcmp(bufptr, "tree ", 5))
 285                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 286         if (tail <= bufptr + 45 || get_sha1_hex(bufptr + 5, parent) < 0)
 287                 return error("bad tree pointer in commit %s",
 288                              sha1_to_hex(item->object.sha1));
 289         item->tree = lookup_tree(parent);
 290         if (item->tree)
 291                 n_refs++;
 292         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 293         pptr = &item->parents;
 294
 295         graft = lookup_commit_graft(item->object.sha1);
 296         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 297                 struct commit *new_parent;
 298
 299                 if (tail <= bufptr + 48 ||
 300                     get_sha1_hex(bufptr + 7, parent) ||
 301                     bufptr[47] != '\n')
 302                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 303                 bufptr += 48;
 304                 if (graft)
 305                         continue;
 306                 new_parent = lookup_commit(parent);
 307                 if (new_parent) {
 308                         pptr = &commit_list_insert(new_parent, pptr)->next;
 309                         n_refs++;
 310                 }
 311         }
 312         if (graft) {
 313                 int i;
 314                 struct commit *new_parent;
 315                 for (i = 0; i < graft->nr_parent; i++) {
 316                         new_parent = lookup_commit(graft->parent[i]);
 317                         if (!new_parent)
 318                                 continue;
 319                         pptr = &commit_list_insert(new_parent, pptr)->next;
 320                         n_refs++;
 321                 }
 322         }
 323         item->date = parse_commit_date(bufptr);
 324
 325         if (track_object_refs) {
 326                 unsigned i = 0;
 327                 struct commit_list *p;
 328                 struct object_refs *refs = alloc_object_refs(n_refs);
 329                 if (item->tree)
 330                         refs->ref[i++] = &item->tree->object;
 331                 for (p = item->parents; p; p = p->next)
 332                         refs->ref[i++] = &p->item->object;
 333                 set_object_refs(&item->object, refs);
 334         }
 335
 336         return 0;
 337 }
 338
 339 int parse_commit(struct commit *item)
 340 {
 341         char type[20];
 342         void *buffer;
 343         unsigned long size;
 344         int ret;
 345
 346         if (item->object.parsed)
 347                 return 0;
 348         buffer = read_sha1_file(item->object.sha1, type, &size);
 349         if (!buffer)
 350                 return error("Could not read %s",
 351                              sha1_to_hex(item->object.sha1));
 352         if (strcmp(type, commit_type)) {
 353                 free(buffer);
 354                 return error("Object %s not a commit",
 355                              sha1_to_hex(item->object.sha1));
 356         }
 357         ret = parse_commit_buffer(item, buffer, size);
 358         if (save_commit_buffer && !ret) {
 359                 item->buffer = buffer;
 360                 return 0;
 361         }
 362         free(buffer);
 363         return ret;
 364 }
 365
 366 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 367 {
 368         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 369         new_list->item = item;
 370         new_list->next = *list_p;
 371         *list_p = new_list;
 372         return new_list;
 373 }
 374
 375 void free_commit_list(struct commit_list *list)
 376 {
 377         while (list) {
 378                 struct commit_list *temp = list;
 379                 list = temp->next;
 380                 free(temp);
 381         }
 382 }
 383
 384 struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 385 {
 386         struct commit_list **pp = list;
 387         struct commit_list *p;
 388         while ((p = *pp) != NULL) {
 389                 if (p->item->date < item->date) {
 390                         break;
 391                 }
 392                 pp = &p->next;
 393         }
 394         return commit_list_insert(item, pp);
 395 }
 396
 397
 398 void sort_by_date(struct commit_list **list)
 399 {
 400         struct commit_list *ret = NULL;
 401         while (*list) {
 402                 insert_by_date((*list)->item, &ret);
 403                 *list = (*list)->next;
 404         }
 405         *list = ret;
 406 }
 407
 408 struct commit *pop_most_recent_commit(struct commit_list **list,
 409                                       unsigned int mark)
 410 {
 411         struct commit *ret = (*list)->item;
 412         struct commit_list *parents = ret->parents;
 413         struct commit_list *old = *list;
 414
 415         *list = (*list)->next;
 416         free(old);
 417
 418         while (parents) {
 419                 struct commit *commit = parents->item;
 420                 parse_commit(commit);
 421                 if (!(commit->object.flags & mark)) {
 422                         commit->object.flags |= mark;
 423                         insert_by_date(commit, list);
 424                 }
 425                 parents = parents->next;
 426         }
 427         return ret;
 428 }
 429
 430 void clear_commit_marks(struct commit *commit, unsigned int mark)
 431 {
 432         struct commit_list *parents;
 433
 434         commit->object.flags &= ~mark;
 435         parents = commit->parents;
 436         while (parents) {
 437                 struct commit *parent = parents->item;
 438
 439                 /* Have we already cleared this? */
 440                 if (mark & parent->object.flags)
 441                         clear_commit_marks(parent, mark);
 442                 parents = parents->next;
 443         }
 444 }
 445
 446 /*
 447  * Generic support for pretty-printing the header
 448  */
 449 static int get_one_line(const char *msg, unsigned long len)
 450 {
 451         int ret = 0;
 452
 453         while (len--) {
 454                 char c = *msg++;
 455                 if (!c)
 456                         break;
 457                 ret++;
 458                 if (c == '\n')
 459                         break;
 460         }
 461         return ret;
 462 }
 463
 464 static int is_rfc2047_special(char ch)
 465 {
 466         return ((ch & 0x80) || (ch == '=') || (ch == '?') || (ch == '_'));
 467 }
 468
 469 static int add_rfc2047(char *buf, const char *line, int len)
 470 {
 471         char *bp = buf;
 472         int i, needquote;
 473         static const char q_utf8[] = "=?utf-8?q?";
 474
 475         for (i = needquote = 0; !needquote && i < len; i++) {
 476                 unsigned ch = line[i];
 477                 if (ch & 0x80)
 478                         needquote++;
 479                 if ((i + 1 < len) &&
 480                     (ch == '=' && line[i+1] == '?'))
 481                         needquote++;
 482         }
 483         if (!needquote)
 484                 return sprintf(buf, "%.*s", len, line);
 485
 486         memcpy(bp, q_utf8, sizeof(q_utf8)-1);
 487         bp += sizeof(q_utf8)-1;
 488         for (i = 0; i < len; i++) {
 489                 unsigned ch = line[i] & 0xFF;
 490                 if (is_rfc2047_special(ch)) {
 491                         sprintf(bp, "=%02X", ch);
 492                         bp += 3;
 493                 }
 494                 else if (ch == ' ')
 495                         *bp++ = '_';
 496                 else
 497                         *bp++ = ch;
 498         }
 499         memcpy(bp, "?=", 2);
 500         bp += 2;
 501         return bp - buf;
 502 }
 503
 504 static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf,
 505                          const char *line, int relative_date)
 506 {
 507         char *date;
 508         int namelen;
 509         unsigned long time;
 510         int tz, ret;
 511         const char *filler = "    ";
 512
 513         if (fmt == CMIT_FMT_ONELINE)
 514                 return 0;
 515         date = strchr(line, '>');
 516         if (!date)
 517                 return 0;
 518         namelen = ++date - line;
 519         time = strtoul(date, &date, 10);
 520         tz = strtol(date, NULL, 10);
 521
 522         if (fmt == CMIT_FMT_EMAIL) {
 523                 char *name_tail = strchr(line, '<');
 524                 int display_name_length;
 525                 if (!name_tail)
 526                         return 0;
 527                 while (line < name_tail && isspace(name_tail[-1]))
 528                         name_tail--;
 529                 display_name_length = name_tail - line;
 530                 filler = "";
 531                 strcpy(buf, "From: ");
 532                 ret = strlen(buf);
 533                 ret += add_rfc2047(buf + ret, line, display_name_length);
 534                 memcpy(buf + ret, name_tail, namelen - display_name_length);
 535                 ret += namelen - display_name_length;
 536                 buf[ret++] = '\n';
 537         }
 538         else {
 539                 ret = sprintf(buf, "%s: %.*s%.*s\n", what,
 540                               (fmt == CMIT_FMT_FULLER) ? 4 : 0,
 541                               filler, namelen, line);
 542         }
 543         switch (fmt) {
 544         case CMIT_FMT_MEDIUM:
 545                 ret += sprintf(buf + ret, "Date:   %s\n",
 546                                show_date(time, tz, relative_date));
 547                 break;
 548         case CMIT_FMT_EMAIL:
 549                 ret += sprintf(buf + ret, "Date: %s\n",
 550                                show_rfc2822_date(time, tz));
 551                 break;
 552         case CMIT_FMT_FULLER:
 553                 ret += sprintf(buf + ret, "%sDate: %s\n", what,
 554                                show_date(time, tz, relative_date));
 555                 break;
 556         default:
 557                 /* notin' */
 558                 break;
 559         }
 560         return ret;
 561 }
 562
 563 static int is_empty_line(const char *line, int *len_p)
 564 {
 565         int len = *len_p;
 566         while (len && isspace(line[len-1]))
 567                 len--;
 568         *len_p = len;
 569         return !len;
 570 }
 571
 572 static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 573 {
 574         struct commit_list *parent = commit->parents;
 575         int offset;
 576
 577         if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
 578             !parent || !parent->next)
 579                 return 0;
 580
 581         offset = sprintf(buf, "Merge:");
 582
 583         while (parent) {
 584                 struct commit *p = parent->item;
 585                 const char *hex = NULL;
 586                 const char *dots;
 587                 if (abbrev)
 588                         hex = find_unique_abbrev(p->object.sha1, abbrev);
 589                 if (!hex)
 590                         hex = sha1_to_hex(p->object.sha1);
 591                 dots = (abbrev && strlen(hex) != 40) ?  "..." : "";
 592                 parent = parent->next;
 593
 594                 offset += sprintf(buf + offset, " %s%s", hex, dots);
 595         }
 596         buf[offset++] = '\n';
 597         return offset;
 598 }
 599
 600 unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit,
 601                                   unsigned long len, char *buf, unsigned long space,
 602                                   int abbrev, const char *subject,
 603                                   const char *after_subject, int relative_date)
 604 {
 605         int hdr = 1, body = 0;
 606         unsigned long offset = 0;
 607         int indent = 4;
 608         int parents_shown = 0;
 609         const char *msg = commit->buffer;
 610         int plain_non_ascii = 0;
 611
 612         if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
 613                 indent = 0;
 614
 615         /* After-subject is used to pass in Content-Type: multipart
 616          * MIME header; in that case we do not have to do the
 617          * plaintext content type even if the commit message has
 618          * non 7-bit ASCII character.  Otherwise, check if we need
 619          * to say this is not a 7-bit ASCII.
 620          */
 621         if (fmt == CMIT_FMT_EMAIL && !after_subject) {
 622                 int i, ch, in_body;
 623
 624                 for (in_body = i = 0; (ch = msg[i]) && i < len; i++) {
 625                         if (!in_body) {
 626                                 /* author could be non 7-bit ASCII but
 627                                  * the log may so; skip over the
 628                                  * header part first.
 629                                  */
 630                                 if (ch == '\n' &&
 631                                     i + 1 < len && msg[i+1] == '\n')
 632                                         in_body = 1;
 633                         }
 634                         else if (ch & 0x80) {
 635                                 plain_non_ascii = 1;
 636                                 break;
 637                         }
 638                 }
 639         }
 640
 641         for (;;) {
 642                 const char *line = msg;
 643                 int linelen = get_one_line(msg, len);
 644
 645                 if (!linelen)
 646                         break;
 647
 648                 /*
 649                  * We want some slop for indentation and a possible
 650                  * final "...". Thus the "+ 20".
 651                  */
 652                 if (offset + linelen + 20 > space) {
 653                         memcpy(buf + offset, "    ...\n", 8);
 654                         offset += 8;
 655                         break;
 656                 }
 657
 658                 msg += linelen;
 659                 len -= linelen;
 660                 if (hdr) {
 661                         if (linelen == 1) {
 662                                 hdr = 0;
 663                                 if ((fmt != CMIT_FMT_ONELINE) && !subject)
 664                                         buf[offset++] = '\n';
 665                                 continue;
 666                         }
 667                         if (fmt == CMIT_FMT_RAW) {
 668                                 memcpy(buf + offset, line, linelen);
 669                                 offset += linelen;
 670                                 continue;
 671                         }
 672                         if (!memcmp(line, "parent ", 7)) {
 673                                 if (linelen != 48)
 674                                         die("bad parent line in commit");
 675                                 continue;
 676                         }
 677
 678                         if (!parents_shown) {
 679                                 offset += add_merge_info(fmt, buf + offset,
 680                                                          commit, abbrev);
 681                                 parents_shown = 1;
 682                                 continue;
 683                         }
 684                         /*
 685                          * MEDIUM == DEFAULT shows only author with dates.
 686                          * FULL shows both authors but not dates.
 687                          * FULLER shows both authors and dates.
 688                          */
 689                         if (!memcmp(line, "author ", 7))
 690                                 offset += add_user_info("Author", fmt,
 691                                                         buf + offset,
 692                                                         line + 7,
 693                                                         relative_date);
 694                         if (!memcmp(line, "committer ", 10) &&
 695                             (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
 696                                 offset += add_user_info("Commit", fmt,
 697                                                         buf + offset,
 698                                                         line + 10,
 699                                                         relative_date);
 700                         continue;
 701                 }
 702
 703                 if (!subject)
 704                         body = 1;
 705
 706                 if (is_empty_line(line, &linelen)) {
 707                         if (!body)
 708                                 continue;
 709                         if (subject)
 710                                 continue;
 711                         if (fmt == CMIT_FMT_SHORT)
 712                                 break;
 713                 }
 714
 715                 if (subject) {
 716                         int slen = strlen(subject);
 717                         memcpy(buf + offset, subject, slen);
 718                         offset += slen;
 719                         offset += add_rfc2047(buf + offset, line, linelen);
 720                 }
 721                 else {
 722                         memset(buf + offset, ' ', indent);
 723                         memcpy(buf + offset + indent, line, linelen);
 724                         offset += linelen + indent;
 725                 }
 726                 buf[offset++] = '\n';
 727                 if (fmt == CMIT_FMT_ONELINE)
 728                         break;
 729                 if (subject && plain_non_ascii) {
 730                         static const char header[] =
 731                                 "Content-Type: text/plain; charset=UTF-8\n"
 732                                 "Content-Transfer-Encoding: 8bit\n";
 733                         memcpy(buf + offset, header, sizeof(header)-1);
 734                         offset += sizeof(header)-1;
 735                 }
 736                 if (after_subject) {
 737                         int slen = strlen(after_subject);
 738                         if (slen > space - offset - 1)
 739                                 slen = space - offset - 1;
 740                         memcpy(buf + offset, after_subject, slen);
 741                         offset += slen;
 742                         after_subject = NULL;
 743                 }
 744                 subject = NULL;
 745         }
 746         while (offset && isspace(buf[offset-1]))
 747                 offset--;
 748         /* Make sure there is an EOLN for the non-oneline case */
 749         if (fmt != CMIT_FMT_ONELINE)
 750                 buf[offset++] = '\n';
 751         /*
 752          * make sure there is another EOLN to separate the headers from whatever
 753          * body the caller appends if we haven't already written a body
 754          */
 755         if (fmt == CMIT_FMT_EMAIL && !body)
 756                 buf[offset++] = '\n';
 757         buf[offset] = '\0';
 758         return offset;
 759 }
 760
 761 struct commit *pop_commit(struct commit_list **stack)
 762 {
 763         struct commit_list *top = *stack;
 764         struct commit *item = top ? top->item : NULL;
 765
 766         if (top) {
 767                 *stack = top->next;
 768                 free(top);
 769         }
 770         return item;
 771 }
 772
 773 int count_parents(struct commit * commit)
 774 {
 775         int count;
 776         struct commit_list * parents = commit->parents;
 777         for (count = 0; parents; parents = parents->next,count++)
 778                 ;
 779         return count;
 780 }
 781
 782 void topo_sort_default_setter(struct commit *c, void *data)
 783 {
 784         c->util = data;
 785 }
 786
 787 void *topo_sort_default_getter(struct commit *c)
 788 {
 789         return c->util;
 790 }
 791
 792 /*
 793  * Performs an in-place topological sort on the list supplied.
 794  */
 795 void sort_in_topological_order(struct commit_list ** list, int lifo)
 796 {
 797         sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
 798                                      topo_sort_default_getter);
 799 }
 800
 801 void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 802                                   topo_sort_set_fn_t setter,
 803                                   topo_sort_get_fn_t getter)
 804 {
 805         struct commit_list * next = *list;
 806         struct commit_list * work = NULL, **insert;
 807         struct commit_list ** pptr = list;
 808         struct sort_node * nodes;
 809         struct sort_node * next_nodes;
 810         int count = 0;
 811
 812         /* determine the size of the list */
 813         while (next) {
 814                 next = next->next;
 815                 count++;
 816         }
 817
 818         if (!count)
 819                 return;
 820         /* allocate an array to help sort the list */
 821         nodes = xcalloc(count, sizeof(*nodes));
 822         /* link the list to the array */
 823         next_nodes = nodes;
 824         next=*list;
 825         while (next) {
 826                 next_nodes->list_item = next;
 827                 setter(next->item, next_nodes);
 828                 next_nodes++;
 829                 next = next->next;
 830         }
 831         /* update the indegree */
 832         next=*list;
 833         while (next) {
 834                 struct commit_list * parents = next->item->parents;
 835                 while (parents) {
 836                         struct commit * parent=parents->item;
 837                         struct sort_node * pn = (struct sort_node *) getter(parent);
 838
 839                         if (pn)
 840                                 pn->indegree++;
 841                         parents=parents->next;
 842                 }
 843                 next=next->next;
 844         }
 845         /*
 846          * find the tips
 847          *
 848          * tips are nodes not reachable from any other node in the list
 849          *
 850          * the tips serve as a starting set for the work queue.
 851          */
 852         next=*list;
 853         insert = &work;
 854         while (next) {
 855                 struct sort_node * node = (struct sort_node *) getter(next->item);
 856
 857                 if (node->indegree == 0) {
 858                         insert = &commit_list_insert(next->item, insert)->next;
 859                 }
 860                 next=next->next;
 861         }
 862
 863         /* process the list in topological order */
 864         if (!lifo)
 865                 sort_by_date(&work);
 866         while (work) {
 867                 struct commit * work_item = pop_commit(&work);
 868                 struct sort_node * work_node = (struct sort_node *) getter(work_item);
 869                 struct commit_list * parents = work_item->parents;
 870
 871                 while (parents) {
 872                         struct commit * parent=parents->item;
 873                         struct sort_node * pn = (struct sort_node *) getter(parent);
 874
 875                         if (pn) {
 876                                 /*
 877                                  * parents are only enqueued for emission
 878                                  * when all their children have been emitted thereby
 879                                  * guaranteeing topological order.
 880                                  */
 881                                 pn->indegree--;
 882                                 if (!pn->indegree) {
 883                                         if (!lifo)
 884                                                 insert_by_date(parent, &work);
 885                                         else
 886                                                 commit_list_insert(parent, &work);
 887                                 }
 888                         }
 889                         parents=parents->next;
 890                 }
 891                 /*
 892                  * work_item is a commit all of whose children
 893                  * have already been emitted. we can emit it now.
 894                  */
 895                 *pptr = work_node->list_item;
 896                 pptr = &(*pptr)->next;
 897                 *pptr = NULL;
 898                 setter(work_item, NULL);
 899         }
 900         free(nodes);
 901 }
 902
 903 /* merge-rebase stuff */
 904
 905 /* bits #0..15 in revision.h */
 906 #define PARENT1         (1u<<16)
 907 #define PARENT2         (1u<<17)
 908 #define STALE           (1u<<18)
 909 #define RESULT          (1u<<19)
 910
 911 static struct commit *interesting(struct commit_list *list)
 912 {
 913         while (list) {
 914                 struct commit *commit = list->item;
 915                 list = list->next;
 916                 if (commit->object.flags & STALE)
 917                         continue;
 918                 return commit;
 919         }
 920         return NULL;
 921 }
 922
 923 static struct commit_list *merge_bases(struct commit *one, struct commit *two)
 924 {
 925         struct commit_list *list = NULL;
 926         struct commit_list *result = NULL;
 927
 928         if (one == two)
 929                 /* We do not mark this even with RESULT so we do not
 930                  * have to clean it up.
 931                  */
 932                 return commit_list_insert(one, &result);
 933
 934         parse_commit(one);
 935         parse_commit(two);
 936
 937         one->object.flags |= PARENT1;
 938         two->object.flags |= PARENT2;
 939         insert_by_date(one, &list);
 940         insert_by_date(two, &list);
 941
 942         while (interesting(list)) {
 943                 struct commit *commit;
 944                 struct commit_list *parents;
 945                 struct commit_list *n;
 946                 int flags;
 947
 948                 commit = list->item;
 949                 n = list->next;
 950                 free(list);
 951                 list = n;
 952
 953                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 954                 if (flags == (PARENT1 | PARENT2)) {
 955                         if (!(commit->object.flags & RESULT)) {
 956                                 commit->object.flags |= RESULT;
 957                                 insert_by_date(commit, &result);
 958                         }
 959                         /* Mark parents of a found merge stale */
 960                         flags |= STALE;
 961                 }
 962                 parents = commit->parents;
 963                 while (parents) {
 964                         struct commit *p = parents->item;
 965                         parents = parents->next;
 966                         if ((p->object.flags & flags) == flags)
 967                                 continue;
 968                         parse_commit(p);
 969                         p->object.flags |= flags;
 970                         insert_by_date(p, &list);
 971                 }
 972         }
 973
 974         /* Clean up the result to remove stale ones */
 975         list = result; result = NULL;
 976         while (list) {
 977                 struct commit_list *n = list->next;
 978                 if (!(list->item->object.flags & STALE))
 979                         insert_by_date(list->item, &result);
 980                 free(list);
 981                 list = n;
 982         }
 983         return result;
 984 }
 985
 986 struct commit_list *get_merge_bases(struct commit *one,
 987                                     struct commit *two,
 988                                     int cleanup)
 989 {
 990         const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 991         struct commit_list *list;
 992         struct commit **rslt;
 993         struct commit_list *result;
 994         int cnt, i, j;
 995
 996         result = merge_bases(one, two);
 997         if (one == two)
 998                 return result;
 999         if (!result || !result->next) {
1000                 if (cleanup) {
1001                         clear_commit_marks(one, all_flags);
1002                         clear_commit_marks(two, all_flags);
1003                 }
1004                 return result;
1005         }
1006
1007         /* There are more than one */
1008         cnt = 0;
1009         list = result;
1010         while (list) {
1011                 list = list->next;
1012                 cnt++;
1013         }
1014         rslt = xcalloc(cnt, sizeof(*rslt));
1015         for (list = result, i = 0; list; list = list->next)
1016                 rslt[i++] = list->item;
1017         free_commit_list(result);
1018
1019         clear_commit_marks(one, all_flags);
1020         clear_commit_marks(two, all_flags);
1021         for (i = 0; i < cnt - 1; i++) {
1022                 for (j = i+1; j < cnt; j++) {
1023                         if (!rslt[i] || !rslt[j])
1024                                 continue;
1025                         result = merge_bases(rslt[i], rslt[j]);
1026                         clear_commit_marks(rslt[i], all_flags);
1027                         clear_commit_marks(rslt[j], all_flags);
1028                         for (list = result; list; list = list->next) {
1029                                 if (rslt[i] == list->item)
1030                                         rslt[i] = NULL;
1031                                 if (rslt[j] == list->item)
1032                                         rslt[j] = NULL;
1033                         }
1034                 }
1035         }
1036
1037         /* Surviving ones in rslt[] are the independent results */
1038         result = NULL;
1039         for (i = 0; i < cnt; i++) {
1040                 if (rslt[i])
1041                         insert_by_date(rslt[i], &result);
1042         }
1043         free(rslt);
1044         return result;
1045 }
1046
1047 int in_merge_bases(struct commit *rev1, struct commit *rev2)
1048 {
1049         struct commit_list *bases, *b;
1050         int ret = 0;
1051
1052         bases = get_merge_bases(rev1, rev2, 1);
1053         for (b = bases; b; b = b->next) {
1054                 if (!hashcmp(rev1->object.sha1, b->item->object.sha1)) {
1055                         ret = 1;
1056                         break;
1057                 }
1058         }
1059
1060         free_commit_list(bases);
1061         return ret;
1062 }