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 != TYPE_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 = TYPE_COMMIT;
  90                 return ret;
  91         }
  92         if (!obj->type)
  93                 obj->type = TYPE_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 = memcmp(sha1, graft->sha1, 20);
 127                 if (!cmp)
 128                         return mi;
 129                 if (cmp < 0)
 130                         hi = mi;
 131                 else
 132                         lo = mi + 1;
 133         }
 134         return -lo - 1;
 135 }
 136
 137 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 138 {
 139         int pos = commit_graft_pos(graft->sha1);
 140
 141         if (0 <= pos) {
 142                 if (ignore_dups)
 143                         free(graft);
 144                 else {
 145                         free(commit_graft[pos]);
 146                         commit_graft[pos] = graft;
 147                 }
 148                 return 1;
 149         }
 150         pos = -pos - 1;
 151         if (commit_graft_alloc <= ++commit_graft_nr) {
 152                 commit_graft_alloc = alloc_nr(commit_graft_alloc);
 153                 commit_graft = xrealloc(commit_graft,
 154                                         sizeof(*commit_graft) *
 155                                         commit_graft_alloc);
 156         }
 157         if (pos < commit_graft_nr)
 158                 memmove(commit_graft + pos + 1,
 159                         commit_graft + pos,
 160                         (commit_graft_nr - pos - 1) *
 161                         sizeof(*commit_graft));
 162         commit_graft[pos] = graft;
 163         return 0;
 164 }
 165
 166 struct commit_graft *read_graft_line(char *buf, int len)
 167 {
 168         /* The format is just "Commit Parent1 Parent2 ...\n" */
 169         int i;
 170         struct commit_graft *graft = NULL;
 171
 172         if (buf[len-1] == '\n')
 173                 buf[--len] = 0;
 174         if (buf[0] == '#' || buf[0] == '\0')
 175                 return NULL;
 176         if ((len + 1) % 41) {
 177         bad_graft_data:
 178                 error("bad graft data: %s", buf);
 179                 free(graft);
 180                 return NULL;
 181         }
 182         i = (len + 1) / 41 - 1;
 183         graft = xmalloc(sizeof(*graft) + 20 * i);
 184         graft->nr_parent = i;
 185         if (get_sha1_hex(buf, graft->sha1))
 186                 goto bad_graft_data;
 187         for (i = 40; i < len; i += 41) {
 188                 if (buf[i] != ' ')
 189                         goto bad_graft_data;
 190                 if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 191                         goto bad_graft_data;
 192         }
 193         return graft;
 194 }
 195
 196 int read_graft_file(const char *graft_file)
 197 {
 198         FILE *fp = fopen(graft_file, "r");
 199         char buf[1024];
 200         if (!fp)
 201                 return -1;
 202         while (fgets(buf, sizeof(buf), fp)) {
 203                 /* The format is just "Commit Parent1 Parent2 ...\n" */
 204                 int len = strlen(buf);
 205                 struct commit_graft *graft = read_graft_line(buf, len);
 206                 if (!graft)
 207                         continue;
 208                 if (register_commit_graft(graft, 1))
 209                         error("duplicate graft data: %s", buf);
 210         }
 211         fclose(fp);
 212         return 0;
 213 }
 214
 215 static void prepare_commit_graft(void)
 216 {
 217         static int commit_graft_prepared;
 218         char *graft_file;
 219
 220         if (commit_graft_prepared)
 221                 return;
 222         graft_file = get_graft_file();
 223         read_graft_file(graft_file);
 224         commit_graft_prepared = 1;
 225 }
 226
 227 static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 228 {
 229         int pos;
 230         prepare_commit_graft();
 231         pos = commit_graft_pos(sha1);
 232         if (pos < 0)
 233                 return NULL;
 234         return commit_graft[pos];
 235 }
 236
 237 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 238 {
 239         char *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, const char *line)
 471 {
 472         char *date;
 473         int namelen;
 474         unsigned long time;
 475         int tz, ret;
 476         const char *filler = "    ";
 477
 478         if (fmt == CMIT_FMT_ONELINE)
 479                 return 0;
 480         date = strchr(line, '>');
 481         if (!date)
 482                 return 0;
 483         namelen = ++date - line;
 484         time = strtoul(date, &date, 10);
 485         tz = strtol(date, NULL, 10);
 486
 487         if (fmt == CMIT_FMT_EMAIL) {
 488                 char *name_tail = strchr(line, '<');
 489                 int display_name_length;
 490                 if (!name_tail)
 491                         return 0;
 492                 while (line < name_tail && isspace(name_tail[-1]))
 493                         name_tail--;
 494                 display_name_length = name_tail - line;
 495                 filler = "";
 496                 strcpy(buf, "From: ");
 497                 ret = strlen(buf);
 498                 ret += add_rfc2047(buf + ret, line, display_name_length);
 499                 memcpy(buf + ret, name_tail, namelen - display_name_length);
 500                 ret += namelen - display_name_length;
 501                 buf[ret++] = '\n';
 502         }
 503         else {
 504                 ret = sprintf(buf, "%s: %.*s%.*s\n", what,
 505                               (fmt == CMIT_FMT_FULLER) ? 4 : 0,
 506                               filler, namelen, line);
 507         }
 508         switch (fmt) {
 509         case CMIT_FMT_MEDIUM:
 510                 ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
 511                 break;
 512         case CMIT_FMT_EMAIL:
 513                 ret += sprintf(buf + ret, "Date: %s\n",
 514                                show_rfc2822_date(time, tz));
 515                 break;
 516         case CMIT_FMT_FULLER:
 517                 ret += sprintf(buf + ret, "%sDate: %s\n", what, show_date(time, tz));
 518                 break;
 519         default:
 520                 /* notin' */
 521                 break;
 522         }
 523         return ret;
 524 }
 525
 526 static int is_empty_line(const char *line, int *len_p)
 527 {
 528         int len = *len_p;
 529         while (len && isspace(line[len-1]))
 530                 len--;
 531         *len_p = len;
 532         return !len;
 533 }
 534
 535 static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 536 {
 537         struct commit_list *parent = commit->parents;
 538         int offset;
 539
 540         if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
 541             !parent || !parent->next)
 542                 return 0;
 543
 544         offset = sprintf(buf, "Merge:");
 545
 546         while (parent) {
 547                 struct commit *p = parent->item;
 548                 const char *hex = abbrev
 549                         ? find_unique_abbrev(p->object.sha1, abbrev)
 550                         : sha1_to_hex(p->object.sha1);
 551                 const char *dots = (abbrev && strlen(hex) != 40) ? "..." : "";
 552                 parent = parent->next;
 553
 554                 offset += sprintf(buf + offset, " %s%s", hex, dots);
 555         }
 556         buf[offset++] = '\n';
 557         return offset;
 558 }
 559
 560 unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit, unsigned long len, char *buf, unsigned long space, int abbrev, const char *subject, const char *after_subject)
 561 {
 562         int hdr = 1, body = 0;
 563         unsigned long offset = 0;
 564         int indent = 4;
 565         int parents_shown = 0;
 566         const char *msg = commit->buffer;
 567         int plain_non_ascii = 0;
 568
 569         if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
 570                 indent = 0;
 571
 572         /* After-subject is used to pass in Content-Type: multipart
 573          * MIME header; in that case we do not have to do the
 574          * plaintext content type even if the commit message has
 575          * non 7-bit ASCII character.  Otherwise, check if we need
 576          * to say this is not a 7-bit ASCII.
 577          */
 578         if (fmt == CMIT_FMT_EMAIL && !after_subject) {
 579                 int i, ch, in_body;
 580
 581                 for (in_body = i = 0; (ch = msg[i]) && i < len; i++) {
 582                         if (!in_body) {
 583                                 /* author could be non 7-bit ASCII but
 584                                  * the log may so; skip over the
 585                                  * header part first.
 586                                  */
 587                                 if (ch == '\n' &&
 588                                     i + 1 < len && msg[i+1] == '\n')
 589                                         in_body = 1;
 590                         }
 591                         else if (ch & 0x80) {
 592                                 plain_non_ascii = 1;
 593                                 break;
 594                         }
 595                 }
 596         }
 597
 598         for (;;) {
 599                 const char *line = msg;
 600                 int linelen = get_one_line(msg, len);
 601
 602                 if (!linelen)
 603                         break;
 604
 605                 /*
 606                  * We want some slop for indentation and a possible
 607                  * final "...". Thus the "+ 20".
 608                  */
 609                 if (offset + linelen + 20 > space) {
 610                         memcpy(buf + offset, "    ...\n", 8);
 611                         offset += 8;
 612                         break;
 613                 }
 614
 615                 msg += linelen;
 616                 len -= linelen;
 617                 if (hdr) {
 618                         if (linelen == 1) {
 619                                 hdr = 0;
 620                                 if ((fmt != CMIT_FMT_ONELINE) && !subject)
 621                                         buf[offset++] = '\n';
 622                                 continue;
 623                         }
 624                         if (fmt == CMIT_FMT_RAW) {
 625                                 memcpy(buf + offset, line, linelen);
 626                                 offset += linelen;
 627                                 continue;
 628                         }
 629                         if (!memcmp(line, "parent ", 7)) {
 630                                 if (linelen != 48)
 631                                         die("bad parent line in commit");
 632                                 continue;
 633                         }
 634
 635                         if (!parents_shown) {
 636                                 offset += add_merge_info(fmt, buf + offset,
 637                                                          commit, abbrev);
 638                                 parents_shown = 1;
 639                                 continue;
 640                         }
 641                         /*
 642                          * MEDIUM == DEFAULT shows only author with dates.
 643                          * FULL shows both authors but not dates.
 644                          * FULLER shows both authors and dates.
 645                          */
 646                         if (!memcmp(line, "author ", 7))
 647                                 offset += add_user_info("Author", fmt,
 648                                                         buf + offset,
 649                                                         line + 7);
 650                         if (!memcmp(line, "committer ", 10) &&
 651                             (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
 652                                 offset += add_user_info("Commit", fmt,
 653                                                         buf + offset,
 654                                                         line + 10);
 655                         continue;
 656                 }
 657
 658                 if (is_empty_line(line, &linelen)) {
 659                         if (!body)
 660                                 continue;
 661                         if (subject)
 662                                 continue;
 663                         if (fmt == CMIT_FMT_SHORT)
 664                                 break;
 665                 } else {
 666                         body = 1;
 667                 }
 668
 669                 if (subject) {
 670                         int slen = strlen(subject);
 671                         memcpy(buf + offset, subject, slen);
 672                         offset += slen;
 673                         offset += add_rfc2047(buf + offset, line, linelen);
 674                 }
 675                 else {
 676                         memset(buf + offset, ' ', indent);
 677                         memcpy(buf + offset + indent, line, linelen);
 678                         offset += linelen + indent;
 679                 }
 680                 buf[offset++] = '\n';
 681                 if (fmt == CMIT_FMT_ONELINE)
 682                         break;
 683                 if (subject && plain_non_ascii) {
 684                         static const char header[] =
 685                                 "Content-Type: text/plain; charset=UTF-8\n"
 686                                 "Content-Transfer-Encoding: 8bit\n";
 687                         memcpy(buf + offset, header, sizeof(header)-1);
 688                         offset += sizeof(header)-1;
 689                 }
 690                 if (after_subject) {
 691                         int slen = strlen(after_subject);
 692                         if (slen > space - offset - 1)
 693                                 slen = space - offset - 1;
 694                         memcpy(buf + offset, after_subject, slen);
 695                         offset += slen;
 696                         after_subject = NULL;
 697                 }
 698                 subject = NULL;
 699         }
 700         while (offset && isspace(buf[offset-1]))
 701                 offset--;
 702         /* Make sure there is an EOLN for the non-oneline case */
 703         if (fmt != CMIT_FMT_ONELINE)
 704                 buf[offset++] = '\n';
 705         buf[offset] = '\0';
 706         return offset;
 707 }
 708
 709 struct commit *pop_commit(struct commit_list **stack)
 710 {
 711         struct commit_list *top = *stack;
 712         struct commit *item = top ? top->item : NULL;
 713
 714         if (top) {
 715                 *stack = top->next;
 716                 free(top);
 717         }
 718         return item;
 719 }
 720
 721 int count_parents(struct commit * commit)
 722 {
 723         int count = 0;
 724         struct commit_list * parents = commit->parents;
 725         for (count=0;parents; parents=parents->next,count++)
 726           ;
 727         return count;
 728 }
 729
 730 void topo_sort_default_setter(struct commit *c, void *data)
 731 {
 732         c->util = data;
 733 }
 734
 735 void *topo_sort_default_getter(struct commit *c)
 736 {
 737         return c->util;
 738 }
 739
 740 /*
 741  * Performs an in-place topological sort on the list supplied.
 742  */
 743 void sort_in_topological_order(struct commit_list ** list, int lifo)
 744 {
 745         sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
 746                                      topo_sort_default_getter);
 747 }
 748
 749 void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 750                                   topo_sort_set_fn_t setter,
 751                                   topo_sort_get_fn_t getter)
 752 {
 753         struct commit_list * next = *list;
 754         struct commit_list * work = NULL, **insert;
 755         struct commit_list ** pptr = list;
 756         struct sort_node * nodes;
 757         struct sort_node * next_nodes;
 758         int count = 0;
 759
 760         /* determine the size of the list */
 761         while (next) {
 762                 next = next->next;
 763                 count++;
 764         }
 765
 766         if (!count)
 767                 return;
 768         /* allocate an array to help sort the list */
 769         nodes = xcalloc(count, sizeof(*nodes));
 770         /* link the list to the array */
 771         next_nodes = nodes;
 772         next=*list;
 773         while (next) {
 774                 next_nodes->list_item = next;
 775                 setter(next->item, next_nodes);
 776                 next_nodes++;
 777                 next = next->next;
 778         }
 779         /* update the indegree */
 780         next=*list;
 781         while (next) {
 782                 struct commit_list * parents = next->item->parents;
 783                 while (parents) {
 784                         struct commit * parent=parents->item;
 785                         struct sort_node * pn = (struct sort_node *) getter(parent);
 786
 787                         if (pn)
 788                                 pn->indegree++;
 789                         parents=parents->next;
 790                 }
 791                 next=next->next;
 792         }
 793         /*
 794          * find the tips
 795          *
 796          * tips are nodes not reachable from any other node in the list
 797          *
 798          * the tips serve as a starting set for the work queue.
 799          */
 800         next=*list;
 801         insert = &work;
 802         while (next) {
 803                 struct sort_node * node = (struct sort_node *) getter(next->item);
 804
 805                 if (node->indegree == 0) {
 806                         insert = &commit_list_insert(next->item, insert)->next;
 807                 }
 808                 next=next->next;
 809         }
 810
 811         /* process the list in topological order */
 812         if (!lifo)
 813                 sort_by_date(&work);
 814         while (work) {
 815                 struct commit * work_item = pop_commit(&work);
 816                 struct sort_node * work_node = (struct sort_node *) getter(work_item);
 817                 struct commit_list * parents = work_item->parents;
 818
 819                 while (parents) {
 820                         struct commit * parent=parents->item;
 821                         struct sort_node * pn = (struct sort_node *) getter(parent);
 822
 823                         if (pn) {
 824                                 /*
 825                                  * parents are only enqueued for emission
 826                                  * when all their children have been emitted thereby
 827                                  * guaranteeing topological order.
 828                                  */
 829                                 pn->indegree--;
 830                                 if (!pn->indegree) {
 831                                         if (!lifo)
 832                                                 insert_by_date(parent, &work);
 833                                         else
 834                                                 commit_list_insert(parent, &work);
 835                                 }
 836                         }
 837                         parents=parents->next;
 838                 }
 839                 /*
 840                  * work_item is a commit all of whose children
 841                  * have already been emitted. we can emit it now.
 842                  */
 843                 *pptr = work_node->list_item;
 844                 pptr = &(*pptr)->next;
 845                 *pptr = NULL;
 846                 setter(work_item, NULL);
 847         }
 848         free(nodes);
 849 }
 850
 851 /* merge-rebase stuff */
 852
 853 /* bits #0..7 in revision.h */
 854 #define PARENT1         (1u<< 8)
 855 #define PARENT2         (1u<< 9)
 856 #define STALE           (1u<<10)
 857
 858 static struct commit *interesting(struct commit_list *list)
 859 {
 860         while (list) {
 861                 struct commit *commit = list->item;
 862                 list = list->next;
 863                 if (commit->object.flags & STALE)
 864                         continue;
 865                 return commit;
 866         }
 867         return NULL;
 868 }
 869
 870 /*
 871  * A pathological example of how this thing works.
 872  *
 873  * Suppose we had this commit graph, where chronologically
 874  * the timestamp on the commit are A <= B <= C <= D <= E <= F
 875  * and we are trying to figure out the merge base for E and F
 876  * commits.
 877  *
 878  *                  F
 879  *                 / \
 880  *            E   A   D
 881  *             \ /   /
 882  *              B   /
 883  *               \ /
 884  *                C
 885  *
 886  * First we push E and F to list to be processed.  E gets bit 1
 887  * and F gets bit 2.  The list becomes:
 888  *
 889  *     list=F(2) E(1), result=empty
 890  *
 891  * Then we pop F, the newest commit, from the list.  Its flag is 2.
 892  * We scan its parents, mark them reachable from the side that F is
 893  * reachable from, and push them to the list:
 894  *
 895  *     list=E(1) D(2) A(2), result=empty
 896  *
 897  * Next pop E and do the same.
 898  *
 899  *     list=D(2) B(1) A(2), result=empty
 900  *
 901  * Next pop D and do the same.
 902  *
 903  *     list=C(2) B(1) A(2), result=empty
 904  *
 905  * Next pop C and do the same.
 906  *
 907  *     list=B(1) A(2), result=empty
 908  *
 909  * Now it is B's turn.  We mark its parent, C, reachable from B's side,
 910  * and push it to the list:
 911  *
 912  *     list=C(3) A(2), result=empty
 913  *
 914  * Now pop C and notice it has flags==3.  It is placed on the result list,
 915  * and the list now contains:
 916  *
 917  *     list=A(2), result=C(3)
 918  *
 919  * We pop A and do the same.
 920  *
 921  *     list=B(3), result=C(3)
 922  *
 923  * Next, we pop B and something very interesting happens.  It has flags==3
 924  * so it is also placed on the result list, and its parents are marked
 925  * stale, retroactively, and placed back on the list:
 926  *
 927  *    list=C(7), result=C(7) B(3)
 928  *
 929  * Now, list does not have any interesting commit.  So we find the newest
 930  * commit from the result list that is not marked stale.  Which is
 931  * commit B.
 932  *
 933  *
 934  * Another pathological example how this thing used to fail to mark an
 935  * ancestor of a merge base as STALE before we introduced the
 936  * postprocessing phase (mark_reachable_commits).
 937  *
 938  *                2
 939  *                H
 940  *          1    / \
 941  *          G   A   \
 942  *          |\ /     \
 943  *          | B       \
 944  *          |  \       \
 945  *           \  C       F
 946  *            \  \     /
 947  *             \  D   /
 948  *              \ |  /
 949  *               \| /
 950  *                E
 951  *
 952  *       list                   A B C D E F G H
 953  *       G1 H2                  - - - - - - 1 2
 954  *       H2 E1 B1               - 1 - - 1 - 1 2
 955  *       F2 E1 B1 A2            2 1 - - 1 2 1 2
 956  *       E3 B1 A2               2 1 - - 3 2 1 2
 957  *       B1 A2                  2 1 - - 3 2 1 2
 958  *       C1 A2                  2 1 1 - 3 2 1 2
 959  *       D1 A2                  2 1 1 1 3 2 1 2
 960  *       A2                     2 1 1 1 3 2 1 2
 961  *       B3                     2 3 1 1 3 2 1 2
 962  *       C7                     2 3 7 1 3 2 1 2
 963  *
 964  * At this point, unfortunately, everybody in the list is
 965  * stale, so we fail to complete the following two
 966  * steps to fully marking stale commits.
 967  *
 968  *       D7                     2 3 7 7 3 2 1 2
 969  *       E7                     2 3 7 7 7 2 1 2
 970  *
 971  * and we ended up showing E as an interesting merge base.
 972  * The postprocessing phase re-injects C and continues traversal
 973  * to contaminate D and E.
 974  */
 975
 976 static void mark_reachable_commits(struct commit_list *result,
 977                                    struct commit_list *list)
 978 {
 979         struct commit_list *tmp;
 980
 981         /*
 982          * Postprocess to fully contaminate the well.
 983          */
 984         for (tmp = result; tmp; tmp = tmp->next) {
 985                 struct commit *c = tmp->item;
 986                 /* Reinject stale ones to list,
 987                  * so we can scan their parents.
 988                  */
 989                 if (c->object.flags & STALE)
 990                         commit_list_insert(c, &list);
 991         }
 992         while (list) {
 993                 struct commit *c = list->item;
 994                 struct commit_list *parents;
 995
 996                 tmp = list;
 997                 list = list->next;
 998                 free(tmp);
 999
1000                 /* Anything taken out of the list is stale, so
1001                  * mark all its parents stale.  We do not
1002                  * parse new ones (we already parsed all the relevant
1003                  * ones).
1004                  */
1005                 parents = c->parents;
1006                 while (parents) {
1007                         struct commit *p = parents->item;
1008                         parents = parents->next;
1009                         if (!(p->object.flags & STALE)) {
1010                                 p->object.flags |= STALE;
1011                                 commit_list_insert(p, &list);
1012                         }
1013                 }
1014         }
1015 }
1016
1017 struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2,
1018                                     int cleanup)
1019 {
1020         struct commit_list *list = NULL;
1021         struct commit_list *result = NULL;
1022         struct commit_list *tmp = NULL;
1023
1024         if (rev1 == rev2)
1025                 return commit_list_insert(rev1, &result);
1026
1027         parse_commit(rev1);
1028         parse_commit(rev2);
1029
1030         rev1->object.flags |= PARENT1;
1031         rev2->object.flags |= PARENT2;
1032         insert_by_date(rev1, &list);
1033         insert_by_date(rev2, &list);
1034
1035         while (interesting(list)) {
1036                 struct commit *commit = list->item;
1037                 struct commit_list *parents;
1038                 int flags = commit->object.flags
1039                         & (PARENT1 | PARENT2 | STALE);
1040
1041                 tmp = list;
1042                 list = list->next;
1043                 free(tmp);
1044                 if (flags == (PARENT1 | PARENT2)) {
1045                         insert_by_date(commit, &result);
1046
1047                         /* Mark parents of a found merge stale */
1048                         flags |= STALE;
1049                 }
1050                 parents = commit->parents;
1051                 while (parents) {
1052                         struct commit *p = parents->item;
1053                         parents = parents->next;
1054                         if ((p->object.flags & flags) == flags)
1055                                 continue;
1056                         parse_commit(p);
1057                         p->object.flags |= flags;
1058                         insert_by_date(p, &list);
1059                 }
1060         }
1061
1062         if (!result)
1063                 goto finish;
1064
1065         if (result->next && list)
1066                 mark_reachable_commits(result, list);
1067
1068         /* cull duplicates */
1069         for (tmp = result, list = NULL; tmp; ) {
1070                 struct commit *commit = tmp->item;
1071                 struct commit_list *next = tmp->next;
1072                 if (commit->object.flags & STALE) {
1073                         if (list != NULL)
1074                                 list->next = next;
1075                         free(tmp);
1076                 } else {
1077                         if (list == NULL)
1078                                 result = tmp;
1079                         list = tmp;
1080                         commit->object.flags |= STALE;
1081                 }
1082
1083                 tmp = next;
1084         }
1085
1086  finish:
1087         if (cleanup) {
1088                 clear_commit_marks(rev1, PARENT1 | PARENT2 | STALE);
1089                 clear_commit_marks(rev2, PARENT1 | PARENT2 | STALE);
1090         }
1091
1092         return result;
1093 }