commit.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "pkt-line.h"
   5 #include "utf8.h"
   6
   7 int save_commit_buffer = 1;
   8
   9 struct sort_node
  10 {
  11         /*
  12          * the number of children of the associated commit
  13          * that also occur in the list being sorted.
  14          */
  15         unsigned int indegree;
  16
  17         /*
  18          * reference to original list item that we will re-use
  19          * on output.
  20          */
  21         struct commit_list * list_item;
  22
  23 };
  24
  25 const char *commit_type = "commit";
  26
  27 struct cmt_fmt_map {
  28         const char *n;
  29         size_t cmp_len;
  30         enum cmit_fmt v;
  31 } cmt_fmts[] = {
  32         { "raw",        1,      CMIT_FMT_RAW },
  33         { "medium",     1,      CMIT_FMT_MEDIUM },
  34         { "short",      1,      CMIT_FMT_SHORT },
  35         { "email",      1,      CMIT_FMT_EMAIL },
  36         { "full",       5,      CMIT_FMT_FULL },
  37         { "fuller",     5,      CMIT_FMT_FULLER },
  38         { "oneline",    1,      CMIT_FMT_ONELINE },
  39 };
  40
  41 enum cmit_fmt get_commit_format(const char *arg)
  42 {
  43         int i;
  44
  45         if (!arg || !*arg)
  46                 return CMIT_FMT_DEFAULT;
  47         if (*arg == '=')
  48                 arg++;
  49         for (i = 0; i < ARRAY_SIZE(cmt_fmts); i++) {
  50                 if (!strncmp(arg, cmt_fmts[i].n, cmt_fmts[i].cmp_len))
  51                         return cmt_fmts[i].v;
  52         }
  53
  54         die("invalid --pretty format: %s", arg);
  55 }
  56
  57 static struct commit *check_commit(struct object *obj,
  58                                    const unsigned char *sha1,
  59                                    int quiet)
  60 {
  61         if (obj->type != OBJ_COMMIT) {
  62                 if (!quiet)
  63                         error("Object %s is a %s, not a commit",
  64                               sha1_to_hex(sha1), typename(obj->type));
  65                 return NULL;
  66         }
  67         return (struct commit *) obj;
  68 }
  69
  70 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  71                                               int quiet)
  72 {
  73         struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  74
  75         if (!obj)
  76                 return NULL;
  77         return check_commit(obj, sha1, quiet);
  78 }
  79
  80 struct commit *lookup_commit_reference(const unsigned char *sha1)
  81 {
  82         return lookup_commit_reference_gently(sha1, 0);
  83 }
  84
  85 struct commit *lookup_commit(const unsigned char *sha1)
  86 {
  87         struct object *obj = lookup_object(sha1);
  88         if (!obj) {
  89                 struct commit *ret = alloc_commit_node();
  90                 created_object(sha1, &ret->object);
  91                 ret->object.type = OBJ_COMMIT;
  92                 return ret;
  93         }
  94         if (!obj->type)
  95                 obj->type = OBJ_COMMIT;
  96         return check_commit(obj, sha1, 0);
  97 }
  98
  99 static unsigned long parse_commit_date(const char *buf)
 100 {
 101         unsigned long date;
 102
 103         if (memcmp(buf, "author", 6))
 104                 return 0;
 105         while (*buf++ != '\n')
 106                 /* nada */;
 107         if (memcmp(buf, "committer", 9))
 108                 return 0;
 109         while (*buf++ != '>')
 110                 /* nada */;
 111         date = strtoul(buf, NULL, 10);
 112         if (date == ULONG_MAX)
 113                 date = 0;
 114         return date;
 115 }
 116
 117 static struct commit_graft **commit_graft;
 118 static int commit_graft_alloc, commit_graft_nr;
 119
 120 static int commit_graft_pos(const unsigned char *sha1)
 121 {
 122         int lo, hi;
 123         lo = 0;
 124         hi = commit_graft_nr;
 125         while (lo < hi) {
 126                 int mi = (lo + hi) / 2;
 127                 struct commit_graft *graft = commit_graft[mi];
 128                 int cmp = hashcmp(sha1, graft->sha1);
 129                 if (!cmp)
 130                         return mi;
 131                 if (cmp < 0)
 132                         hi = mi;
 133                 else
 134                         lo = mi + 1;
 135         }
 136         return -lo - 1;
 137 }
 138
 139 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 140 {
 141         int pos = commit_graft_pos(graft->sha1);
 142
 143         if (0 <= pos) {
 144                 if (ignore_dups)
 145                         free(graft);
 146                 else {
 147                         free(commit_graft[pos]);
 148                         commit_graft[pos] = graft;
 149                 }
 150                 return 1;
 151         }
 152         pos = -pos - 1;
 153         if (commit_graft_alloc <= ++commit_graft_nr) {
 154                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 155                 commit_graft = xrealloc(commit_graft,
 156                                         sizeof(*commit_graft) *
 157                                         commit_graft_alloc);
 158         }
 159         if (pos < commit_graft_nr)
 160                 memmove(commit_graft + pos + 1,
 161                         commit_graft + pos,
 162                         (commit_graft_nr - pos - 1) *
 163                         sizeof(*commit_graft));
 164         commit_graft[pos] = graft;
 165         return 0;
 166 }
 167
 168 struct commit_graft *read_graft_line(char *buf, int len)
 169 {
 170         /* The format is just "Commit Parent1 Parent2 ...\n" */
 171         int i;
 172         struct commit_graft *graft = NULL;
 173
 174         if (buf[len-1] == '\n')
 175                 buf[--len] = 0;
 176         if (buf[0] == '#' || buf[0] == '\0')
 177                 return NULL;
 178         if ((len + 1) % 41) {
 179         bad_graft_data:
 180                 error("bad graft data: %s", buf);
 181                 free(graft);
 182                 return NULL;
 183         }
 184         i = (len + 1) / 41 - 1;
 185         graft = xmalloc(sizeof(*graft) + 20 * i);
 186         graft->nr_parent = i;
 187         if (get_sha1_hex(buf, graft->sha1))
 188                 goto bad_graft_data;
 189         for (i = 40; i < len; i += 41) {
 190                 if (buf[i] != ' ')
 191                         goto bad_graft_data;
 192                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 193                         goto bad_graft_data;
 194         }
 195         return graft;
 196 }
 197
 198 int read_graft_file(const char *graft_file)
 199 {
 200         FILE *fp = fopen(graft_file, "r");
 201         char buf[1024];
 202         if (!fp)
 203                 return -1;
 204         while (fgets(buf, sizeof(buf), fp)) {
 205                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 206                 int len = strlen(buf);
 207                 struct commit_graft *graft = read_graft_line(buf, len);
 208                 if (!graft)
 209                         continue;
 210                 if (register_commit_graft(graft, 1))
 211                         error("duplicate graft data: %s", buf);
 212         }
 213         fclose(fp);
 214         return 0;
 215 }
 216
 217 static void prepare_commit_graft(void)
 218 {
 219         static int commit_graft_prepared;
 220         char *graft_file;
 221
 222         if (commit_graft_prepared)
 223                 return;
 224         graft_file = get_graft_file();
 225         read_graft_file(graft_file);
 226         /* make sure shallows are read */
 227         is_repository_shallow();
 228         commit_graft_prepared = 1;
 229 }
 230
 231 static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 232 {
 233         int pos;
 234         prepare_commit_graft();
 235         pos = commit_graft_pos(sha1);
 236         if (pos < 0)
 237                 return NULL;
 238         return commit_graft[pos];
 239 }
 240
 241 int write_shallow_commits(int fd, int use_pack_protocol)
 242 {
 243         int i, count = 0;
 244         for (i = 0; i < commit_graft_nr; i++)
 245                 if (commit_graft[i]->nr_parent < 0) {
 246                         const char *hex =
 247                                 sha1_to_hex(commit_graft[i]->sha1);
 248                         count++;
 249                         if (use_pack_protocol)
 250                                 packet_write(fd, "shallow %s", hex);
 251                         else {
 252                                 write(fd, hex,  40);
 253                                 write(fd, "\n", 1);
 254                         }
 255                 }
 256         return count;
 257 }
 258
 259 int unregister_shallow(const unsigned char *sha1)
 260 {
 261         int pos = commit_graft_pos(sha1);
 262         if (pos < 0)
 263                 return -1;
 264         if (pos + 1 < commit_graft_nr)
 265                 memcpy(commit_graft + pos, commit_graft + pos + 1,
 266                                 sizeof(struct commit_graft *)
 267                                 * (commit_graft_nr - pos - 1));
 268         commit_graft_nr--;
 269         return 0;
 270 }
 271
 272 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 273 {
 274         char *tail = buffer;
 275         char *bufptr = buffer;
 276         unsigned char parent[20];
 277         struct commit_list **pptr;
 278         struct commit_graft *graft;
 279         unsigned n_refs = 0;
 280
 281         if (item->object.parsed)
 282                 return 0;
 283         item->object.parsed = 1;
 284         tail += size;
 285         if (tail <= bufptr + 5 || memcmp(bufptr, "tree ", 5))
 286                 return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 287         if (tail <= bufptr + 45 || get_sha1_hex(bufptr + 5, parent) < 0)
 288                 return error("bad tree pointer in commit %s",
 289                              sha1_to_hex(item->object.sha1));
 290         item->tree = lookup_tree(parent);
 291         if (item->tree)
 292                 n_refs++;
 293         bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 294         pptr = &item->parents;
 295
 296         graft = lookup_commit_graft(item->object.sha1);
 297         while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 298                 struct commit *new_parent;
 299
 300                 if (tail <= bufptr + 48 ||
 301                     get_sha1_hex(bufptr + 7, parent) ||
 302                     bufptr[47] != '\n')
 303                         return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 304                 bufptr += 48;
 305                 if (graft)
 306                         continue;
 307                 new_parent = lookup_commit(parent);
 308                 if (new_parent) {
 309                         pptr = &commit_list_insert(new_parent, pptr)->next;
 310                         n_refs++;
 311                 }
 312         }
 313         if (graft) {
 314                 int i;
 315                 struct commit *new_parent;
 316                 for (i = 0; i < graft->nr_parent; i++) {
 317                         new_parent = lookup_commit(graft->parent[i]);
 318                         if (!new_parent)
 319                                 continue;
 320                         pptr = &commit_list_insert(new_parent, pptr)->next;
 321                         n_refs++;
 322                 }
 323         }
 324         item->date = parse_commit_date(bufptr);
 325
 326         if (track_object_refs) {
 327                 unsigned i = 0;
 328                 struct commit_list *p;
 329                 struct object_refs *refs = alloc_object_refs(n_refs);
 330                 if (item->tree)
 331                         refs->ref[i++] = &item->tree->object;
 332                 for (p = item->parents; p; p = p->next)
 333                         refs->ref[i++] = &p->item->object;
 334                 set_object_refs(&item->object, refs);
 335         }
 336
 337         return 0;
 338 }
 339
 340 int parse_commit(struct commit *item)
 341 {
 342         char type[20];
 343         void *buffer;
 344         unsigned long size;
 345         int ret;
 346
 347         if (item->object.parsed)
 348                 return 0;
 349         buffer = read_sha1_file(item->object.sha1, type, &size);
 350         if (!buffer)
 351                 return error("Could not read %s",
 352                              sha1_to_hex(item->object.sha1));
 353         if (strcmp(type, commit_type)) {
 354                 free(buffer);
 355                 return error("Object %s not a commit",
 356                              sha1_to_hex(item->object.sha1));
 357         }
 358         ret = parse_commit_buffer(item, buffer, size);
 359         if (save_commit_buffer && !ret) {
 360                 item->buffer = buffer;
 361                 return 0;
 362         }
 363         free(buffer);
 364         return ret;
 365 }
 366
 367 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 368 {
 369         struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 370         new_list->item = item;
 371         new_list->next = *list_p;
 372         *list_p = new_list;
 373         return new_list;
 374 }
 375
 376 void free_commit_list(struct commit_list *list)
 377 {
 378         while (list) {
 379                 struct commit_list *temp = list;
 380                 list = temp->next;
 381                 free(temp);
 382         }
 383 }
 384
 385 struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 386 {
 387         struct commit_list **pp = list;
 388         struct commit_list *p;
 389         while ((p = *pp) != NULL) {
 390                 if (p->item->date < item->date) {
 391                         break;
 392                 }
 393                 pp = &p->next;
 394         }
 395         return commit_list_insert(item, pp);
 396 }
 397
 398
 399 void sort_by_date(struct commit_list **list)
 400 {
 401         struct commit_list *ret = NULL;
 402         while (*list) {
 403                 insert_by_date((*list)->item, &ret);
 404                 *list = (*list)->next;
 405         }
 406         *list = ret;
 407 }
 408
 409 struct commit *pop_most_recent_commit(struct commit_list **list,
 410                                       unsigned int mark)
 411 {
 412         struct commit *ret = (*list)->item;
 413         struct commit_list *parents = ret->parents;
 414         struct commit_list *old = *list;
 415
 416         *list = (*list)->next;
 417         free(old);
 418
 419         while (parents) {
 420                 struct commit *commit = parents->item;
 421                 parse_commit(commit);
 422                 if (!(commit->object.flags & mark)) {
 423                         commit->object.flags |= mark;
 424                         insert_by_date(commit, list);
 425                 }
 426                 parents = parents->next;
 427         }
 428         return ret;
 429 }
 430
 431 void clear_commit_marks(struct commit *commit, unsigned int mark)
 432 {
 433         struct commit_list *parents;
 434
 435         commit->object.flags &= ~mark;
 436         parents = commit->parents;
 437         while (parents) {
 438                 struct commit *parent = parents->item;
 439
 440                 /* Have we already cleared this? */
 441                 if (mark & parent->object.flags)
 442                         clear_commit_marks(parent, mark);
 443                 parents = parents->next;
 444         }
 445 }
 446
 447 /*
 448  * Generic support for pretty-printing the header
 449  */
 450 static int get_one_line(const char *msg, unsigned long len)
 451 {
 452         int ret = 0;
 453
 454         while (len--) {
 455                 char c = *msg++;
 456                 if (!c)
 457                         break;
 458                 ret++;
 459                 if (c == '\n')
 460                         break;
 461         }
 462         return ret;
 463 }
 464
 465 static int is_rfc2047_special(char ch)
 466 {
 467         return ((ch & 0x80) || (ch == '=') || (ch == '?') || (ch == '_'));
 468 }
 469
 470 static int add_rfc2047(char *buf, const char *line, int len)
 471 {
 472         char *bp = buf;
 473         int i, needquote;
 474         static const char q_utf8[] = "=?utf-8?q?";
 475
 476         for (i = needquote = 0; !needquote && i < len; i++) {
 477                 unsigned ch = line[i];
 478                 if (ch & 0x80)
 479                         needquote++;
 480                 if ((i + 1 < len) &&
 481                     (ch == '=' && line[i+1] == '?'))
 482                         needquote++;
 483         }
 484         if (!needquote)
 485                 return sprintf(buf, "%.*s", len, line);
 486
 487         memcpy(bp, q_utf8, sizeof(q_utf8)-1);
 488         bp += sizeof(q_utf8)-1;
 489         for (i = 0; i < len; i++) {
 490                 unsigned ch = line[i] & 0xFF;
 491                 if (is_rfc2047_special(ch)) {
 492                         sprintf(bp, "=%02X", ch);
 493                         bp += 3;
 494                 }
 495                 else if (ch == ' ')
 496                         *bp++ = '_';
 497                 else
 498                         *bp++ = ch;
 499         }
 500         memcpy(bp, "?=", 2);
 501         bp += 2;
 502         return bp - buf;
 503 }
 504
 505 static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf,
 506                          const char *line, int relative_date)
 507 {
 508         char *date;
 509         int namelen;
 510         unsigned long time;
 511         int tz, ret;
 512         const char *filler = "    ";
 513
 514         if (fmt == CMIT_FMT_ONELINE)
 515                 return 0;
 516         date = strchr(line, '>');
 517         if (!date)
 518                 return 0;
 519         namelen = ++date - line;
 520         time = strtoul(date, &date, 10);
 521         tz = strtol(date, NULL, 10);
 522
 523         if (fmt == CMIT_FMT_EMAIL) {
 524                 char *name_tail = strchr(line, '<');
 525                 int display_name_length;
 526                 if (!name_tail)
 527                         return 0;
 528                 while (line < name_tail && isspace(name_tail[-1]))
 529                         name_tail--;
 530                 display_name_length = name_tail - line;
 531                 filler = "";
 532                 strcpy(buf, "From: ");
 533                 ret = strlen(buf);
 534                 ret += add_rfc2047(buf + ret, line, display_name_length);
 535                 memcpy(buf + ret, name_tail, namelen - display_name_length);
 536                 ret += namelen - display_name_length;
 537                 buf[ret++] = '\n';
 538         }
 539         else {
 540                 ret = sprintf(buf, "%s: %.*s%.*s\n", what,
 541                               (fmt == CMIT_FMT_FULLER) ? 4 : 0,
 542                               filler, namelen, line);
 543         }
 544         switch (fmt) {
 545         case CMIT_FMT_MEDIUM:
 546                 ret += sprintf(buf + ret, "Date:   %s\n",
 547                                show_date(time, tz, relative_date));
 548                 break;
 549         case CMIT_FMT_EMAIL:
 550                 ret += sprintf(buf + ret, "Date: %s\n",
 551                                show_rfc2822_date(time, tz));
 552                 break;
 553         case CMIT_FMT_FULLER:
 554                 ret += sprintf(buf + ret, "%sDate: %s\n", what,
 555                                show_date(time, tz, relative_date));
 556                 break;
 557         default:
 558                 /* notin' */
 559                 break;
 560         }
 561         return ret;
 562 }
 563
 564 static int is_empty_line(const char *line, int *len_p)
 565 {
 566         int len = *len_p;
 567         while (len && isspace(line[len-1]))
 568                 len--;
 569         *len_p = len;
 570         return !len;
 571 }
 572
 573 static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 574 {
 575         struct commit_list *parent = commit->parents;
 576         int offset;
 577
 578         if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
 579             !parent || !parent->next)
 580                 return 0;
 581
 582         offset = sprintf(buf, "Merge:");
 583
 584         while (parent) {
 585                 struct commit *p = parent->item;
 586                 const char *hex = NULL;
 587                 const char *dots;
 588                 if (abbrev)
 589                         hex = find_unique_abbrev(p->object.sha1, abbrev);
 590                 if (!hex)
 591                         hex = sha1_to_hex(p->object.sha1);
 592                 dots = (abbrev && strlen(hex) != 40) ?  "..." : "";
 593                 parent = parent->next;
 594
 595                 offset += sprintf(buf + offset, " %s%s", hex, dots);
 596         }
 597         buf[offset++] = '\n';
 598         return offset;
 599 }
 600
 601 static char *get_header(const struct commit *commit, const char *key)
 602 {
 603         int key_len = strlen(key);
 604         const char *line = commit->buffer;
 605
 606         for (;;) {
 607                 const char *eol = strchr(line, '\n'), *next;
 608
 609                 if (line == eol)
 610                         return NULL;
 611                 if (!eol) {
 612                         eol = line + strlen(line);
 613                         next = NULL;
 614                 } else
 615                         next = eol + 1;
 616                 if (!strncmp(line, key, key_len) && line[key_len] == ' ') {
 617                         int len = eol - line - key_len;
 618                         char *ret = xmalloc(len);
 619                         memcpy(ret, line + key_len + 1, len - 1);
 620                         ret[len - 1] = '\0';
 621                         return ret;
 622                 }
 623                 line = next;
 624         }
 625 }
 626
 627 static char *logmsg_reencode(const struct commit *commit)
 628 {
 629         char *encoding;
 630         char *out;
 631         char *output_encoding = (git_log_output_encoding
 632                                  ? git_log_output_encoding
 633                                  : git_commit_encoding);
 634
 635         if (!output_encoding)
 636                 output_encoding = "utf-8";
 637         else if (!*output_encoding)
 638                 return NULL;
 639         encoding = get_header(commit, "encoding");
 640         if (!encoding || !strcmp(encoding, output_encoding)) {
 641                 free(encoding);
 642                 return NULL;
 643         }
 644         out = reencode_string(commit->buffer, output_encoding, encoding);
 645         free(encoding);
 646         if (!out)
 647                 return NULL;
 648         return out;
 649 }
 650
 651 unsigned long pretty_print_commit(enum cmit_fmt fmt,
 652                                   const struct commit *commit,
 653                                   unsigned long len,
 654                                   char *buf, unsigned long space,
 655                                   int abbrev, const char *subject,
 656                                   const char *after_subject,
 657                                   int relative_date)
 658 {
 659         int hdr = 1, body = 0;
 660         unsigned long offset = 0;
 661         int indent = 4;
 662         int parents_shown = 0;
 663         const char *msg = commit->buffer;
 664         int plain_non_ascii = 0;
 665         char *reencoded = logmsg_reencode(commit);
 666
 667         if (reencoded)
 668                 msg = reencoded;
 669
 670         if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
 671                 indent = 0;
 672
 673         /* After-subject is used to pass in Content-Type: multipart
 674          * MIME header; in that case we do not have to do the
 675          * plaintext content type even if the commit message has
 676          * non 7-bit ASCII character.  Otherwise, check if we need
 677          * to say this is not a 7-bit ASCII.
 678          */
 679         if (fmt == CMIT_FMT_EMAIL && !after_subject) {
 680                 int i, ch, in_body;
 681
 682                 for (in_body = i = 0; (ch = msg[i]) && i < len; i++) {
 683                         if (!in_body) {
 684                                 /* author could be non 7-bit ASCII but
 685                                  * the log may be so; skip over the
 686                                  * header part first.
 687                                  */
 688                                 if (ch == '\n' &&
 689                                     i + 1 < len && msg[i+1] == '\n')
 690                                         in_body = 1;
 691                         }
 692                         else if (ch & 0x80) {
 693                                 plain_non_ascii = 1;
 694                                 break;
 695                         }
 696                 }
 697         }
 698
 699         for (;;) {
 700                 const char *line = msg;
 701                 int linelen = get_one_line(msg, len);
 702
 703                 if (!linelen)
 704                         break;
 705
 706                 /*
 707                  * We want some slop for indentation and a possible
 708                  * final "...". Thus the "+ 20".
 709                  */
 710                 if (offset + linelen + 20 > space) {
 711                         memcpy(buf + offset, "    ...\n", 8);
 712                         offset += 8;
 713                         break;
 714                 }
 715
 716                 msg += linelen;
 717                 len -= linelen;
 718                 if (hdr) {
 719                         if (linelen == 1) {
 720                                 hdr = 0;
 721                                 if ((fmt != CMIT_FMT_ONELINE) && !subject)
 722                                         buf[offset++] = '\n';
 723                                 continue;
 724                         }
 725                         if (fmt == CMIT_FMT_RAW) {
 726                                 memcpy(buf + offset, line, linelen);
 727                                 offset += linelen;
 728                                 continue;
 729                         }
 730                         if (!memcmp(line, "parent ", 7)) {
 731                                 if (linelen != 48)
 732                                         die("bad parent line in commit");
 733                                 continue;
 734                         }
 735
 736                         if (!parents_shown) {
 737                                 offset += add_merge_info(fmt, buf + offset,
 738                                                          commit, abbrev);
 739                                 parents_shown = 1;
 740                                 continue;
 741                         }
 742                         /*
 743                          * MEDIUM == DEFAULT shows only author with dates.
 744                          * FULL shows both authors but not dates.
 745                          * FULLER shows both authors and dates.
 746                          */
 747                         if (!memcmp(line, "author ", 7))
 748                                 offset += add_user_info("Author", fmt,
 749                                                         buf + offset,
 750                                                         line + 7,
 751                                                         relative_date);
 752                         if (!memcmp(line, "committer ", 10) &&
 753                             (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
 754                                 offset += add_user_info("Commit", fmt,
 755                                                         buf + offset,
 756                                                         line + 10,
 757                                                         relative_date);
 758                         continue;
 759                 }
 760
 761                 if (!subject)
 762                         body = 1;
 763
 764                 if (is_empty_line(line, &linelen)) {
 765                         if (!body)
 766                                 continue;
 767                         if (subject)
 768                                 continue;
 769                         if (fmt == CMIT_FMT_SHORT)
 770                                 break;
 771                 }
 772
 773                 if (subject) {
 774                         int slen = strlen(subject);
 775                         memcpy(buf + offset, subject, slen);
 776                         offset += slen;
 777                         offset += add_rfc2047(buf + offset, line, linelen);
 778                 }
 779                 else {
 780                         memset(buf + offset, ' ', indent);
 781                         memcpy(buf + offset + indent, line, linelen);
 782                         offset += linelen + indent;
 783                 }
 784                 buf[offset++] = '\n';
 785                 if (fmt == CMIT_FMT_ONELINE)
 786                         break;
 787                 if (subject && plain_non_ascii) {
 788                         static const char header[] =
 789                                 "Content-Type: text/plain; charset=UTF-8\n"
 790                                 "Content-Transfer-Encoding: 8bit\n";
 791                         memcpy(buf + offset, header, sizeof(header)-1);
 792                         offset += sizeof(header)-1;
 793                 }
 794                 if (after_subject) {
 795                         int slen = strlen(after_subject);
 796                         if (slen > space - offset - 1)
 797                                 slen = space - offset - 1;
 798                         memcpy(buf + offset, after_subject, slen);
 799                         offset += slen;
 800                         after_subject = NULL;
 801                 }
 802                 subject = NULL;
 803         }
 804         while (offset && isspace(buf[offset-1]))
 805                 offset--;
 806         /* Make sure there is an EOLN for the non-oneline case */
 807         if (fmt != CMIT_FMT_ONELINE)
 808                 buf[offset++] = '\n';
 809         /*
 810          * make sure there is another EOLN to separate the headers from whatever
 811          * body the caller appends if we haven't already written a body
 812          */
 813         if (fmt == CMIT_FMT_EMAIL && !body)
 814                 buf[offset++] = '\n';
 815         buf[offset] = '\0';
 816
 817         free(reencoded);
 818         return offset;
 819 }
 820
 821 struct commit *pop_commit(struct commit_list **stack)
 822 {
 823         struct commit_list *top = *stack;
 824         struct commit *item = top ? top->item : NULL;
 825
 826         if (top) {
 827                 *stack = top->next;
 828                 free(top);
 829         }
 830         return item;
 831 }
 832
 833 int count_parents(struct commit * commit)
 834 {
 835         int count;
 836         struct commit_list * parents = commit->parents;
 837         for (count = 0; parents; parents = parents->next,count++)
 838                 ;
 839         return count;
 840 }
 841
 842 void topo_sort_default_setter(struct commit *c, void *data)
 843 {
 844         c->util = data;
 845 }
 846
 847 void *topo_sort_default_getter(struct commit *c)
 848 {
 849         return c->util;
 850 }
 851
 852 /*
 853  * Performs an in-place topological sort on the list supplied.
 854  */
 855 void sort_in_topological_order(struct commit_list ** list, int lifo)
 856 {
 857         sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
 858                                      topo_sort_default_getter);
 859 }
 860
 861 void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 862                                   topo_sort_set_fn_t setter,
 863                                   topo_sort_get_fn_t getter)
 864 {
 865         struct commit_list * next = *list;
 866         struct commit_list * work = NULL, **insert;
 867         struct commit_list ** pptr = list;
 868         struct sort_node * nodes;
 869         struct sort_node * next_nodes;
 870         int count = 0;
 871
 872         /* determine the size of the list */
 873         while (next) {
 874                 next = next->next;
 875                 count++;
 876         }
 877
 878         if (!count)
 879                 return;
 880         /* allocate an array to help sort the list */
 881         nodes = xcalloc(count, sizeof(*nodes));
 882         /* link the list to the array */
 883         next_nodes = nodes;
 884         next=*list;
 885         while (next) {
 886                 next_nodes->list_item = next;
 887                 setter(next->item, next_nodes);
 888                 next_nodes++;
 889                 next = next->next;
 890         }
 891         /* update the indegree */
 892         next=*list;
 893         while (next) {
 894                 struct commit_list * parents = next->item->parents;
 895                 while (parents) {
 896                         struct commit * parent=parents->item;
 897                         struct sort_node * pn = (struct sort_node *) getter(parent);
 898
 899                         if (pn)
 900                                 pn->indegree++;
 901                         parents=parents->next;
 902                 }
 903                 next=next->next;
 904         }
 905         /*
 906          * find the tips
 907          *
 908          * tips are nodes not reachable from any other node in the list
 909          *
 910          * the tips serve as a starting set for the work queue.
 911          */
 912         next=*list;
 913         insert = &work;
 914         while (next) {
 915                 struct sort_node * node = (struct sort_node *) getter(next->item);
 916
 917                 if (node->indegree == 0) {
 918                         insert = &commit_list_insert(next->item, insert)->next;
 919                 }
 920                 next=next->next;
 921         }
 922
 923         /* process the list in topological order */
 924         if (!lifo)
 925                 sort_by_date(&work);
 926         while (work) {
 927                 struct commit * work_item = pop_commit(&work);
 928                 struct sort_node * work_node = (struct sort_node *) getter(work_item);
 929                 struct commit_list * parents = work_item->parents;
 930
 931                 while (parents) {
 932                         struct commit * parent=parents->item;
 933                         struct sort_node * pn = (struct sort_node *) getter(parent);
 934
 935                         if (pn) {
 936                                 /*
 937                                  * parents are only enqueued for emission
 938                                  * when all their children have been emitted thereby
 939                                  * guaranteeing topological order.
 940                                  */
 941                                 pn->indegree--;
 942                                 if (!pn->indegree) {
 943                                         if (!lifo)
 944                                                 insert_by_date(parent, &work);
 945                                         else
 946                                                 commit_list_insert(parent, &work);
 947                                 }
 948                         }
 949                         parents=parents->next;
 950                 }
 951                 /*
 952                  * work_item is a commit all of whose children
 953                  * have already been emitted. we can emit it now.
 954                  */
 955                 *pptr = work_node->list_item;
 956                 pptr = &(*pptr)->next;
 957                 *pptr = NULL;
 958                 setter(work_item, NULL);
 959         }
 960         free(nodes);
 961 }
 962
 963 /* merge-rebase stuff */
 964
 965 /* bits #0..15 in revision.h */
 966 #define PARENT1         (1u<<16)
 967 #define PARENT2         (1u<<17)
 968 #define STALE           (1u<<18)
 969 #define RESULT          (1u<<19)
 970
 971 static struct commit *interesting(struct commit_list *list)
 972 {
 973         while (list) {
 974                 struct commit *commit = list->item;
 975                 list = list->next;
 976                 if (commit->object.flags & STALE)
 977                         continue;
 978                 return commit;
 979         }
 980         return NULL;
 981 }
 982
 983 static struct commit_list *merge_bases(struct commit *one, struct commit *two)
 984 {
 985         struct commit_list *list = NULL;
 986         struct commit_list *result = NULL;
 987
 988         if (one == two)
 989                 /* We do not mark this even with RESULT so we do not
 990                  * have to clean it up.
 991                  */
 992                 return commit_list_insert(one, &result);
 993
 994         parse_commit(one);
 995         parse_commit(two);
 996
 997         one->object.flags |= PARENT1;
 998         two->object.flags |= PARENT2;
 999         insert_by_date(one, &list);
1000         insert_by_date(two, &list);
1001
1002         while (interesting(list)) {
1003                 struct commit *commit;
1004                 struct commit_list *parents;
1005                 struct commit_list *n;
1006                 int flags;
1007
1008                 commit = list->item;
1009                 n = list->next;
1010                 free(list);
1011                 list = n;
1012
1013                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
1014                 if (flags == (PARENT1 | PARENT2)) {
1015                         if (!(commit->object.flags & RESULT)) {
1016                                 commit->object.flags |= RESULT;
1017                                 insert_by_date(commit, &result);
1018                         }
1019                         /* Mark parents of a found merge stale */
1020                         flags |= STALE;
1021                 }
1022                 parents = commit->parents;
1023                 while (parents) {
1024                         struct commit *p = parents->item;
1025                         parents = parents->next;
1026                         if ((p->object.flags & flags) == flags)
1027                                 continue;
1028                         parse_commit(p);
1029                         p->object.flags |= flags;
1030                         insert_by_date(p, &list);
1031                 }
1032         }
1033
1034         /* Clean up the result to remove stale ones */
1035         list = result; result = NULL;
1036         while (list) {
1037                 struct commit_list *n = list->next;
1038                 if (!(list->item->object.flags & STALE))
1039                         insert_by_date(list->item, &result);
1040                 free(list);
1041                 list = n;
1042         }
1043         return result;
1044 }
1045
1046 struct commit_list *get_merge_bases(struct commit *one,
1047                                     struct commit *two,
1048                                     int cleanup)
1049 {
1050         const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
1051         struct commit_list *list;
1052         struct commit **rslt;
1053         struct commit_list *result;
1054         int cnt, i, j;
1055
1056         result = merge_bases(one, two);
1057         if (one == two)
1058                 return result;
1059         if (!result || !result->next) {
1060                 if (cleanup) {
1061                         clear_commit_marks(one, all_flags);
1062                         clear_commit_marks(two, all_flags);
1063                 }
1064                 return result;
1065         }
1066
1067         /* There are more than one */
1068         cnt = 0;
1069         list = result;
1070         while (list) {
1071                 list = list->next;
1072                 cnt++;
1073         }
1074         rslt = xcalloc(cnt, sizeof(*rslt));
1075         for (list = result, i = 0; list; list = list->next)
1076                 rslt[i++] = list->item;
1077         free_commit_list(result);
1078
1079         clear_commit_marks(one, all_flags);
1080         clear_commit_marks(two, all_flags);
1081         for (i = 0; i < cnt - 1; i++) {
1082                 for (j = i+1; j < cnt; j++) {
1083                         if (!rslt[i] || !rslt[j])
1084                                 continue;
1085                         result = merge_bases(rslt[i], rslt[j]);
1086                         clear_commit_marks(rslt[i], all_flags);
1087                         clear_commit_marks(rslt[j], all_flags);
1088                         for (list = result; list; list = list->next) {
1089                                 if (rslt[i] == list->item)
1090                                         rslt[i] = NULL;
1091                                 if (rslt[j] == list->item)
1092                                         rslt[j] = NULL;
1093                         }
1094                 }
1095         }
1096
1097         /* Surviving ones in rslt[] are the independent results */
1098         result = NULL;
1099         for (i = 0; i < cnt; i++) {
1100                 if (rslt[i])
1101                         insert_by_date(rslt[i], &result);
1102         }
1103         free(rslt);
1104         return result;
1105 }
1106
1107 int in_merge_bases(struct commit *rev1, struct commit *rev2)
1108 {
1109         struct commit_list *bases, *b;
1110         int ret = 0;
1111
1112         bases = get_merge_bases(rev1, rev2, 1);
1113         for (b = bases; b; b = b->next) {
1114                 if (!hashcmp(rev1->object.sha1, b->item->object.sha1)) {
1115                         ret = 1;
1116                         break;
1117                 }
1118         }
1119
1120         free_commit_list(bases);
1121         return ret;
1122 }