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 parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 259 {
 260         char *tail = buffer;
 261         char *bufptr = buffer;
 262         unsigned char parent[20];
 263         struct commit_list **pptr;
 264         struct commit_graft *graft;
 265         unsigned n_refs = 0;
 266
 267         if (item->object.parsed)
 268                 return 0;
 269         item->object.parsed = 1;
 270         tail += size;
 271         if (tail <= bufptr + 5 || memcmp(bufptr, "tree ", 5))
 272                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 273         if (tail <= bufptr + 45 || get_sha1_hex(bufptr + 5, parent) < 0)
 274                 return error("bad tree pointer in commit %s",
 275                              sha1_to_hex(item->object.sha1));
 276         item->tree = lookup_tree(parent);
 277         if (item->tree)
 278                 n_refs++;
 279         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 280         pptr = &item->parents;
 281
 282         graft = lookup_commit_graft(item->object.sha1);
 283         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 284                 struct commit *new_parent;
 285
 286                 if (tail <= bufptr + 48 ||
 287                     get_sha1_hex(bufptr + 7, parent) ||
 288                     bufptr[47] != '\n')
 289                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 290                 bufptr += 48;
 291                 if (graft)
 292                         continue;
 293                 new_parent = lookup_commit(parent);
 294                 if (new_parent) {
 295                         pptr = &commit_list_insert(new_parent, pptr)->next;
 296                         n_refs++;
 297                 }
 298         }
 299         if (graft) {
 300                 int i;
 301                 struct commit *new_parent;
 302                 for (i = 0; i < graft->nr_parent; i++) {
 303                         new_parent = lookup_commit(graft->parent[i]);
 304                         if (!new_parent)
 305                                 continue;
 306                         pptr = &commit_list_insert(new_parent, pptr)->next;
 307                         n_refs++;
 308                 }
 309         }
 310         item->date = parse_commit_date(bufptr);
 311
 312         if (track_object_refs) {
 313                 unsigned i = 0;
 314                 struct commit_list *p;
 315                 struct object_refs *refs = alloc_object_refs(n_refs);
 316                 if (item->tree)
 317                         refs->ref[i++] = &item->tree->object;
 318                 for (p = item->parents; p; p = p->next)
 319                         refs->ref[i++] = &p->item->object;
 320                 set_object_refs(&item->object, refs);
 321         }
 322
 323         return 0;
 324 }
 325
 326 int parse_commit(struct commit *item)
 327 {
 328         char type[20];
 329         void *buffer;
 330         unsigned long size;
 331         int ret;
 332
 333         if (item->object.parsed)
 334                 return 0;
 335         buffer = read_sha1_file(item->object.sha1, type, &size);
 336         if (!buffer)
 337                 return error("Could not read %s",
 338                              sha1_to_hex(item->object.sha1));
 339         if (strcmp(type, commit_type)) {
 340                 free(buffer);
 341                 return error("Object %s not a commit",
 342                              sha1_to_hex(item->object.sha1));
 343         }
 344         ret = parse_commit_buffer(item, buffer, size);
 345         if (save_commit_buffer && !ret) {
 346                 item->buffer = buffer;
 347                 return 0;
 348         }
 349         free(buffer);
 350         return ret;
 351 }
 352
 353 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 354 {
 355         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 356         new_list->item = item;
 357         new_list->next = *list_p;
 358         *list_p = new_list;
 359         return new_list;
 360 }
 361
 362 void free_commit_list(struct commit_list *list)
 363 {
 364         while (list) {
 365                 struct commit_list *temp = list;
 366                 list = temp->next;
 367                 free(temp);
 368         }
 369 }
 370
 371 struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 372 {
 373         struct commit_list **pp = list;
 374         struct commit_list *p;
 375         while ((p = *pp) != NULL) {
 376                 if (p->item->date < item->date) {
 377                         break;
 378                 }
 379                 pp = &p->next;
 380         }
 381         return commit_list_insert(item, pp);
 382 }
 383
 384
 385 void sort_by_date(struct commit_list **list)
 386 {
 387         struct commit_list *ret = NULL;
 388         while (*list) {
 389                 insert_by_date((*list)->item, &ret);
 390                 *list = (*list)->next;
 391         }
 392         *list = ret;
 393 }
 394
 395 struct commit *pop_most_recent_commit(struct commit_list **list,
 396                                       unsigned int mark)
 397 {
 398         struct commit *ret = (*list)->item;
 399         struct commit_list *parents = ret->parents;
 400         struct commit_list *old = *list;
 401
 402         *list = (*list)->next;
 403         free(old);
 404
 405         while (parents) {
 406                 struct commit *commit = parents->item;
 407                 parse_commit(commit);
 408                 if (!(commit->object.flags & mark)) {
 409                         commit->object.flags |= mark;
 410                         insert_by_date(commit, list);
 411                 }
 412                 parents = parents->next;
 413         }
 414         return ret;
 415 }
 416
 417 void clear_commit_marks(struct commit *commit, unsigned int mark)
 418 {
 419         struct commit_list *parents;
 420
 421         commit->object.flags &= ~mark;
 422         parents = commit->parents;
 423         while (parents) {
 424                 struct commit *parent = parents->item;
 425
 426                 /* Have we already cleared this? */
 427                 if (mark & parent->object.flags)
 428                         clear_commit_marks(parent, mark);
 429                 parents = parents->next;
 430         }
 431 }
 432
 433 /*
 434  * Generic support for pretty-printing the header
 435  */
 436 static int get_one_line(const char *msg, unsigned long len)
 437 {
 438         int ret = 0;
 439
 440         while (len--) {
 441                 char c = *msg++;
 442                 if (!c)
 443                         break;
 444                 ret++;
 445                 if (c == '\n')
 446                         break;
 447         }
 448         return ret;
 449 }
 450
 451 static int is_rfc2047_special(char ch)
 452 {
 453         return ((ch & 0x80) || (ch == '=') || (ch == '?') || (ch == '_'));
 454 }
 455
 456 static int add_rfc2047(char *buf, const char *line, int len)
 457 {
 458         char *bp = buf;
 459         int i, needquote;
 460         static const char q_utf8[] = "=?utf-8?q?";
 461
 462         for (i = needquote = 0; !needquote && i < len; i++) {
 463                 unsigned ch = line[i];
 464                 if (ch & 0x80)
 465                         needquote++;
 466                 if ((i + 1 < len) &&
 467                     (ch == '=' && line[i+1] == '?'))
 468                         needquote++;
 469         }
 470         if (!needquote)
 471                 return sprintf(buf, "%.*s", len, line);
 472
 473         memcpy(bp, q_utf8, sizeof(q_utf8)-1);
 474         bp += sizeof(q_utf8)-1;
 475         for (i = 0; i < len; i++) {
 476                 unsigned ch = line[i] & 0xFF;
 477                 if (is_rfc2047_special(ch)) {
 478                         sprintf(bp, "=%02X", ch);
 479                         bp += 3;
 480                 }
 481                 else if (ch == ' ')
 482                         *bp++ = '_';
 483                 else
 484                         *bp++ = ch;
 485         }
 486         memcpy(bp, "?=", 2);
 487         bp += 2;
 488         return bp - buf;
 489 }
 490
 491 static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf,
 492                          const char *line, int relative_date)
 493 {
 494         char *date;
 495         int namelen;
 496         unsigned long time;
 497         int tz, ret;
 498         const char *filler = "    ";
 499
 500         if (fmt == CMIT_FMT_ONELINE)
 501                 return 0;
 502         date = strchr(line, '>');
 503         if (!date)
 504                 return 0;
 505         namelen = ++date - line;
 506         time = strtoul(date, &date, 10);
 507         tz = strtol(date, NULL, 10);
 508
 509         if (fmt == CMIT_FMT_EMAIL) {
 510                 char *name_tail = strchr(line, '<');
 511                 int display_name_length;
 512                 if (!name_tail)
 513                         return 0;
 514                 while (line < name_tail && isspace(name_tail[-1]))
 515                         name_tail--;
 516                 display_name_length = name_tail - line;
 517                 filler = "";
 518                 strcpy(buf, "From: ");
 519                 ret = strlen(buf);
 520                 ret += add_rfc2047(buf + ret, line, display_name_length);
 521                 memcpy(buf + ret, name_tail, namelen - display_name_length);
 522                 ret += namelen - display_name_length;
 523                 buf[ret++] = '\n';
 524         }
 525         else {
 526                 ret = sprintf(buf, "%s: %.*s%.*s\n", what,
 527                               (fmt == CMIT_FMT_FULLER) ? 4 : 0,
 528                               filler, namelen, line);
 529         }
 530         switch (fmt) {
 531         case CMIT_FMT_MEDIUM:
 532                 ret += sprintf(buf + ret, "Date:   %s\n",
 533                                show_date(time, tz, relative_date));
 534                 break;
 535         case CMIT_FMT_EMAIL:
 536                 ret += sprintf(buf + ret, "Date: %s\n",
 537                                show_rfc2822_date(time, tz));
 538                 break;
 539         case CMIT_FMT_FULLER:
 540                 ret += sprintf(buf + ret, "%sDate: %s\n", what,
 541                                show_date(time, tz, relative_date));
 542                 break;
 543         default:
 544                 /* notin' */
 545                 break;
 546         }
 547         return ret;
 548 }
 549
 550 static int is_empty_line(const char *line, int *len_p)
 551 {
 552         int len = *len_p;
 553         while (len && isspace(line[len-1]))
 554                 len--;
 555         *len_p = len;
 556         return !len;
 557 }
 558
 559 static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 560 {
 561         struct commit_list *parent = commit->parents;
 562         int offset;
 563
 564         if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
 565             !parent || !parent->next)
 566                 return 0;
 567
 568         offset = sprintf(buf, "Merge:");
 569
 570         while (parent) {
 571                 struct commit *p = parent->item;
 572                 const char *hex = NULL;
 573                 const char *dots;
 574                 if (abbrev)
 575                         hex = find_unique_abbrev(p->object.sha1, abbrev);
 576                 if (!hex)
 577                         hex = sha1_to_hex(p->object.sha1);
 578                 dots = (abbrev && strlen(hex) != 40) ?  "..." : "";
 579                 parent = parent->next;
 580
 581                 offset += sprintf(buf + offset, " %s%s", hex, dots);
 582         }
 583         buf[offset++] = '\n';
 584         return offset;
 585 }
 586
 587 unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit,
 588                                   unsigned long len, char *buf, unsigned long space,
 589                                   int abbrev, const char *subject,
 590                                   const char *after_subject, int relative_date)
 591 {
 592         int hdr = 1, body = 0;
 593         unsigned long offset = 0;
 594         int indent = 4;
 595         int parents_shown = 0;
 596         const char *msg = commit->buffer;
 597         int plain_non_ascii = 0;
 598
 599         if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
 600                 indent = 0;
 601
 602         /* After-subject is used to pass in Content-Type: multipart
 603          * MIME header; in that case we do not have to do the
 604          * plaintext content type even if the commit message has
 605          * non 7-bit ASCII character.  Otherwise, check if we need
 606          * to say this is not a 7-bit ASCII.
 607          */
 608         if (fmt == CMIT_FMT_EMAIL && !after_subject) {
 609                 int i, ch, in_body;
 610
 611                 for (in_body = i = 0; (ch = msg[i]) && i < len; i++) {
 612                         if (!in_body) {
 613                                 /* author could be non 7-bit ASCII but
 614                                  * the log may so; skip over the
 615                                  * header part first.
 616                                  */
 617                                 if (ch == '\n' &&
 618                                     i + 1 < len && msg[i+1] == '\n')
 619                                         in_body = 1;
 620                         }
 621                         else if (ch & 0x80) {
 622                                 plain_non_ascii = 1;
 623                                 break;
 624                         }
 625                 }
 626         }
 627
 628         for (;;) {
 629                 const char *line = msg;
 630                 int linelen = get_one_line(msg, len);
 631
 632                 if (!linelen)
 633                         break;
 634
 635                 /*
 636                  * We want some slop for indentation and a possible
 637                  * final "...". Thus the "+ 20".
 638                  */
 639                 if (offset + linelen + 20 > space) {
 640                         memcpy(buf + offset, "    ...\n", 8);
 641                         offset += 8;
 642                         break;
 643                 }
 644
 645                 msg += linelen;
 646                 len -= linelen;
 647                 if (hdr) {
 648                         if (linelen == 1) {
 649                                 hdr = 0;
 650                                 if ((fmt != CMIT_FMT_ONELINE) && !subject)
 651                                         buf[offset++] = '\n';
 652                                 continue;
 653                         }
 654                         if (fmt == CMIT_FMT_RAW) {
 655                                 memcpy(buf + offset, line, linelen);
 656                                 offset += linelen;
 657                                 continue;
 658                         }
 659                         if (!memcmp(line, "parent ", 7)) {
 660                                 if (linelen != 48)
 661                                         die("bad parent line in commit");
 662                                 continue;
 663                         }
 664
 665                         if (!parents_shown) {
 666                                 offset += add_merge_info(fmt, buf + offset,
 667                                                          commit, abbrev);
 668                                 parents_shown = 1;
 669                                 continue;
 670                         }
 671                         /*
 672                          * MEDIUM == DEFAULT shows only author with dates.
 673                          * FULL shows both authors but not dates.
 674                          * FULLER shows both authors and dates.
 675                          */
 676                         if (!memcmp(line, "author ", 7))
 677                                 offset += add_user_info("Author", fmt,
 678                                                         buf + offset,
 679                                                         line + 7,
 680                                                         relative_date);
 681                         if (!memcmp(line, "committer ", 10) &&
 682                             (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
 683                                 offset += add_user_info("Commit", fmt,
 684                                                         buf + offset,
 685                                                         line + 10,
 686                                                         relative_date);
 687                         continue;
 688                 }
 689
 690                 if (!subject)
 691                         body = 1;
 692
 693                 if (is_empty_line(line, &linelen)) {
 694                         if (!body)
 695                                 continue;
 696                         if (subject)
 697                                 continue;
 698                         if (fmt == CMIT_FMT_SHORT)
 699                                 break;
 700                 }
 701
 702                 if (subject) {
 703                         int slen = strlen(subject);
 704                         memcpy(buf + offset, subject, slen);
 705                         offset += slen;
 706                         offset += add_rfc2047(buf + offset, line, linelen);
 707                 }
 708                 else {
 709                         memset(buf + offset, ' ', indent);
 710                         memcpy(buf + offset + indent, line, linelen);
 711                         offset += linelen + indent;
 712                 }
 713                 buf[offset++] = '\n';
 714                 if (fmt == CMIT_FMT_ONELINE)
 715                         break;
 716                 if (subject && plain_non_ascii) {
 717                         static const char header[] =
 718                                 "Content-Type: text/plain; charset=UTF-8\n"
 719                                 "Content-Transfer-Encoding: 8bit\n";
 720                         memcpy(buf + offset, header, sizeof(header)-1);
 721                         offset += sizeof(header)-1;
 722                 }
 723                 if (after_subject) {
 724                         int slen = strlen(after_subject);
 725                         if (slen > space - offset - 1)
 726                                 slen = space - offset - 1;
 727                         memcpy(buf + offset, after_subject, slen);
 728                         offset += slen;
 729                         after_subject = NULL;
 730                 }
 731                 subject = NULL;
 732         }
 733         while (offset && isspace(buf[offset-1]))
 734                 offset--;
 735         /* Make sure there is an EOLN for the non-oneline case */
 736         if (fmt != CMIT_FMT_ONELINE)
 737                 buf[offset++] = '\n';
 738         /*
 739          * make sure there is another EOLN to separate the headers from whatever
 740          * body the caller appends if we haven't already written a body
 741          */
 742         if (fmt == CMIT_FMT_EMAIL && !body)
 743                 buf[offset++] = '\n';
 744         buf[offset] = '\0';
 745         return offset;
 746 }
 747
 748 struct commit *pop_commit(struct commit_list **stack)
 749 {
 750         struct commit_list *top = *stack;
 751         struct commit *item = top ? top->item : NULL;
 752
 753         if (top) {
 754                 *stack = top->next;
 755                 free(top);
 756         }
 757         return item;
 758 }
 759
 760 int count_parents(struct commit * commit)
 761 {
 762         int count;
 763         struct commit_list * parents = commit->parents;
 764         for (count = 0; parents; parents = parents->next,count++)
 765                 ;
 766         return count;
 767 }
 768
 769 void topo_sort_default_setter(struct commit *c, void *data)
 770 {
 771         c->util = data;
 772 }
 773
 774 void *topo_sort_default_getter(struct commit *c)
 775 {
 776         return c->util;
 777 }
 778
 779 /*
 780  * Performs an in-place topological sort on the list supplied.
 781  */
 782 void sort_in_topological_order(struct commit_list ** list, int lifo)
 783 {
 784         sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
 785                                      topo_sort_default_getter);
 786 }
 787
 788 void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 789                                   topo_sort_set_fn_t setter,
 790                                   topo_sort_get_fn_t getter)
 791 {
 792         struct commit_list * next = *list;
 793         struct commit_list * work = NULL, **insert;
 794         struct commit_list ** pptr = list;
 795         struct sort_node * nodes;
 796         struct sort_node * next_nodes;
 797         int count = 0;
 798
 799         /* determine the size of the list */
 800         while (next) {
 801                 next = next->next;
 802                 count++;
 803         }
 804
 805         if (!count)
 806                 return;
 807         /* allocate an array to help sort the list */
 808         nodes = xcalloc(count, sizeof(*nodes));
 809         /* link the list to the array */
 810         next_nodes = nodes;
 811         next=*list;
 812         while (next) {
 813                 next_nodes->list_item = next;
 814                 setter(next->item, next_nodes);
 815                 next_nodes++;
 816                 next = next->next;
 817         }
 818         /* update the indegree */
 819         next=*list;
 820         while (next) {
 821                 struct commit_list * parents = next->item->parents;
 822                 while (parents) {
 823                         struct commit * parent=parents->item;
 824                         struct sort_node * pn = (struct sort_node *) getter(parent);
 825
 826                         if (pn)
 827                                 pn->indegree++;
 828                         parents=parents->next;
 829                 }
 830                 next=next->next;
 831         }
 832         /*
 833          * find the tips
 834          *
 835          * tips are nodes not reachable from any other node in the list
 836          *
 837          * the tips serve as a starting set for the work queue.
 838          */
 839         next=*list;
 840         insert = &work;
 841         while (next) {
 842                 struct sort_node * node = (struct sort_node *) getter(next->item);
 843
 844                 if (node->indegree == 0) {
 845                         insert = &commit_list_insert(next->item, insert)->next;
 846                 }
 847                 next=next->next;
 848         }
 849
 850         /* process the list in topological order */
 851         if (!lifo)
 852                 sort_by_date(&work);
 853         while (work) {
 854                 struct commit * work_item = pop_commit(&work);
 855                 struct sort_node * work_node = (struct sort_node *) getter(work_item);
 856                 struct commit_list * parents = work_item->parents;
 857
 858                 while (parents) {
 859                         struct commit * parent=parents->item;
 860                         struct sort_node * pn = (struct sort_node *) getter(parent);
 861
 862                         if (pn) {
 863                                 /*
 864                                  * parents are only enqueued for emission
 865                                  * when all their children have been emitted thereby
 866                                  * guaranteeing topological order.
 867                                  */
 868                                 pn->indegree--;
 869                                 if (!pn->indegree) {
 870                                         if (!lifo)
 871                                                 insert_by_date(parent, &work);
 872                                         else
 873                                                 commit_list_insert(parent, &work);
 874                                 }
 875                         }
 876                         parents=parents->next;
 877                 }
 878                 /*
 879                  * work_item is a commit all of whose children
 880                  * have already been emitted. we can emit it now.
 881                  */
 882                 *pptr = work_node->list_item;
 883                 pptr = &(*pptr)->next;
 884                 *pptr = NULL;
 885                 setter(work_item, NULL);
 886         }
 887         free(nodes);
 888 }
 889
 890 /* merge-rebase stuff */
 891
 892 /* bits #0..7 in revision.h */
 893 #define PARENT1         (1u<< 8)
 894 #define PARENT2         (1u<< 9)
 895 #define STALE           (1u<<10)
 896 #define RESULT          (1u<<11)
 897
 898 static struct commit *interesting(struct commit_list *list)
 899 {
 900         while (list) {
 901                 struct commit *commit = list->item;
 902                 list = list->next;
 903                 if (commit->object.flags & STALE)
 904                         continue;
 905                 return commit;
 906         }
 907         return NULL;
 908 }
 909
 910 static struct commit_list *merge_bases(struct commit *one, struct commit *two)
 911 {
 912         struct commit_list *list = NULL;
 913         struct commit_list *result = NULL;
 914
 915         if (one == two)
 916                 /* We do not mark this even with RESULT so we do not
 917                  * have to clean it up.
 918                  */
 919                 return commit_list_insert(one, &result);
 920
 921         parse_commit(one);
 922         parse_commit(two);
 923
 924         one->object.flags |= PARENT1;
 925         two->object.flags |= PARENT2;
 926         insert_by_date(one, &list);
 927         insert_by_date(two, &list);
 928
 929         while (interesting(list)) {
 930                 struct commit *commit;
 931                 struct commit_list *parents;
 932                 struct commit_list *n;
 933                 int flags;
 934
 935                 commit = list->item;
 936                 n = list->next;
 937                 free(list);
 938                 list = n;
 939
 940                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 941                 if (flags == (PARENT1 | PARENT2)) {
 942                         if (!(commit->object.flags & RESULT)) {
 943                                 commit->object.flags |= RESULT;
 944                                 insert_by_date(commit, &result);
 945                         }
 946                         /* Mark parents of a found merge stale */
 947                         flags |= STALE;
 948                 }
 949                 parents = commit->parents;
 950                 while (parents) {
 951                         struct commit *p = parents->item;
 952                         parents = parents->next;
 953                         if ((p->object.flags & flags) == flags)
 954                                 continue;
 955                         parse_commit(p);
 956                         p->object.flags |= flags;
 957                         insert_by_date(p, &list);
 958                 }
 959         }
 960
 961         /* Clean up the result to remove stale ones */
 962         list = result; result = NULL;
 963         while (list) {
 964                 struct commit_list *n = list->next;
 965                 if (!(list->item->object.flags & STALE))
 966                         insert_by_date(list->item, &result);
 967                 free(list);
 968                 list = n;
 969         }
 970         return result;
 971 }
 972
 973 struct commit_list *get_merge_bases(struct commit *one,
 974                                     struct commit *two,
 975                                     int cleanup)
 976 {
 977         const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 978         struct commit_list *list;
 979         struct commit **rslt;
 980         struct commit_list *result;
 981         int cnt, i, j;
 982
 983         result = merge_bases(one, two);
 984         if (one == two)
 985                 return result;
 986         if (!result || !result->next) {
 987                 if (cleanup) {
 988                         clear_commit_marks(one, all_flags);
 989                         clear_commit_marks(two, all_flags);
 990                 }
 991                 return result;
 992         }
 993
 994         /* There are more than one */
 995         cnt = 0;
 996         list = result;
 997         while (list) {
 998                 list = list->next;
 999                 cnt++;
1000         }
1001         rslt = xcalloc(cnt, sizeof(*rslt));
1002         for (list = result, i = 0; list; list = list->next)
1003                 rslt[i++] = list->item;
1004         free_commit_list(result);
1005
1006         clear_commit_marks(one, all_flags);
1007         clear_commit_marks(two, all_flags);
1008         for (i = 0; i < cnt - 1; i++) {
1009                 for (j = i+1; j < cnt; j++) {
1010                         if (!rslt[i] || !rslt[j])
1011                                 continue;
1012                         result = merge_bases(rslt[i], rslt[j]);
1013                         clear_commit_marks(rslt[i], all_flags);
1014                         clear_commit_marks(rslt[j], all_flags);
1015                         for (list = result; list; list = list->next) {
1016                                 if (rslt[i] == list->item)
1017                                         rslt[i] = NULL;
1018                                 if (rslt[j] == list->item)
1019                                         rslt[j] = NULL;
1020                         }
1021                 }
1022         }
1023
1024         /* Surviving ones in rslt[] are the independent results */
1025         result = NULL;
1026         for (i = 0; i < cnt; i++) {
1027                 if (rslt[i])
1028                         insert_by_date(rslt[i], &result);
1029         }
1030         free(rslt);
1031         return result;
1032 }