commit.c

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