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         parents = commit->parents;
 401         commit->object.flags &= ~mark;
 402         while (parents) {
 403                 struct commit *parent = parents->item;
 404                 if (parent && parent->object.parsed &&
 405                     (parent->object.flags & mark))
 406                         clear_commit_marks(parent, mark);
 407                 parents = parents->next;
 408         }
 409 }
 410
 411 /*
 412  * Generic support for pretty-printing the header
 413  */
 414 static int get_one_line(const char *msg, unsigned long len)
 415 {
 416         int ret = 0;
 417
 418         while (len--) {
 419                 char c = *msg++;
 420                 if (!c)
 421                         break;
 422                 ret++;
 423                 if (c == '\n')
 424                         break;
 425         }
 426         return ret;
 427 }
 428
 429 static int is_rfc2047_special(char ch)
 430 {
 431         return ((ch & 0x80) || (ch == '=') || (ch == '?') || (ch == '_'));
 432 }
 433
 434 static int add_rfc2047(char *buf, const char *line, int len)
 435 {
 436         char *bp = buf;
 437         int i, needquote;
 438         static const char q_utf8[] = "=?utf-8?q?";
 439
 440         for (i = needquote = 0; !needquote && i < len; i++) {
 441                 unsigned ch = line[i];
 442                 if (ch & 0x80)
 443                         needquote++;
 444                 if ((i + 1 < len) &&
 445                     (ch == '=' && line[i+1] == '?'))
 446                         needquote++;
 447         }
 448         if (!needquote)
 449                 return sprintf(buf, "%.*s", len, line);
 450
 451         memcpy(bp, q_utf8, sizeof(q_utf8)-1);
 452         bp += sizeof(q_utf8)-1;
 453         for (i = 0; i < len; i++) {
 454                 unsigned ch = line[i] & 0xFF;
 455                 if (is_rfc2047_special(ch)) {
 456                         sprintf(bp, "=%02X", ch);
 457                         bp += 3;
 458                 }
 459                 else if (ch == ' ')
 460                         *bp++ = '_';
 461                 else
 462                         *bp++ = ch;
 463         }
 464         memcpy(bp, "?=", 2);
 465         bp += 2;
 466         return bp - buf;
 467 }
 468
 469 static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
 470 {
 471         char *date;
 472         int namelen;
 473         unsigned long time;
 474         int tz, ret;
 475         const char *filler = "    ";
 476
 477         if (fmt == CMIT_FMT_ONELINE)
 478                 return 0;
 479         date = strchr(line, '>');
 480         if (!date)
 481                 return 0;
 482         namelen = ++date - line;
 483         time = strtoul(date, &date, 10);
 484         tz = strtol(date, NULL, 10);
 485
 486         if (fmt == CMIT_FMT_EMAIL) {
 487                 char *name_tail = strchr(line, '<');
 488                 int display_name_length;
 489                 if (!name_tail)
 490                         return 0;
 491                 while (line < name_tail && isspace(name_tail[-1]))
 492                         name_tail--;
 493                 display_name_length = name_tail - line;
 494                 filler = "";
 495                 strcpy(buf, "From: ");
 496                 ret = strlen(buf);
 497                 ret += add_rfc2047(buf + ret, line, display_name_length);
 498                 memcpy(buf + ret, name_tail, namelen - display_name_length);
 499                 ret += namelen - display_name_length;
 500                 buf[ret++] = '\n';
 501         }
 502         else {
 503                 ret = sprintf(buf, "%s: %.*s%.*s\n", what,
 504                               (fmt == CMIT_FMT_FULLER) ? 4 : 0,
 505                               filler, namelen, line);
 506         }
 507         switch (fmt) {
 508         case CMIT_FMT_MEDIUM:
 509                 ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
 510                 break;
 511         case CMIT_FMT_EMAIL:
 512                 ret += sprintf(buf + ret, "Date: %s\n",
 513                                show_rfc2822_date(time, tz));
 514                 break;
 515         case CMIT_FMT_FULLER:
 516                 ret += sprintf(buf + ret, "%sDate: %s\n", what, show_date(time, tz));
 517                 break;
 518         default:
 519                 /* notin' */
 520                 break;
 521         }
 522         return ret;
 523 }
 524
 525 static int is_empty_line(const char *line, int *len_p)
 526 {
 527         int len = *len_p;
 528         while (len && isspace(line[len-1]))
 529                 len--;
 530         *len_p = len;
 531         return !len;
 532 }
 533
 534 static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
 535 {
 536         struct commit_list *parent = commit->parents;
 537         int offset;
 538
 539         if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
 540             !parent || !parent->next)
 541                 return 0;
 542
 543         offset = sprintf(buf, "Merge:");
 544
 545         while (parent) {
 546                 struct commit *p = parent->item;
 547                 const char *hex = abbrev
 548                         ? find_unique_abbrev(p->object.sha1, abbrev)
 549                         : sha1_to_hex(p->object.sha1);
 550                 const char *dots = (abbrev && strlen(hex) != 40) ? "..." : "";
 551                 parent = parent->next;
 552
 553                 offset += sprintf(buf + offset, " %s%s", hex, dots);
 554         }
 555         buf[offset++] = '\n';
 556         return offset;
 557 }
 558
 559 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)
 560 {
 561         int hdr = 1, body = 0;
 562         unsigned long offset = 0;
 563         int indent = 4;
 564         int parents_shown = 0;
 565         const char *msg = commit->buffer;
 566         int plain_non_ascii = 0;
 567
 568         if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
 569                 indent = 0;
 570
 571         /* After-subject is used to pass in Content-Type: multipart
 572          * MIME header; in that case we do not have to do the
 573          * plaintext content type even if the commit message has
 574          * non 7-bit ASCII character.  Otherwise, check if we need
 575          * to say this is not a 7-bit ASCII.
 576          */
 577         if (fmt == CMIT_FMT_EMAIL && !after_subject) {
 578                 int i, ch, in_body;
 579
 580                 for (in_body = i = 0; (ch = msg[i]) && i < len; i++) {
 581                         if (!in_body) {
 582                                 /* author could be non 7-bit ASCII but
 583                                  * the log may so; skip over the
 584                                  * header part first.
 585                                  */
 586                                 if (ch == '\n' &&
 587                                     i + 1 < len && msg[i+1] == '\n')
 588                                         in_body = 1;
 589                         }
 590                         else if (ch & 0x80) {
 591                                 plain_non_ascii = 1;
 592                                 break;
 593                         }
 594                 }
 595         }
 596
 597         for (;;) {
 598                 const char *line = msg;
 599                 int linelen = get_one_line(msg, len);
 600
 601                 if (!linelen)
 602                         break;
 603
 604                 /*
 605                  * We want some slop for indentation and a possible
 606                  * final "...". Thus the "+ 20".
 607                  */
 608                 if (offset + linelen + 20 > space) {
 609                         memcpy(buf + offset, "    ...\n", 8);
 610                         offset += 8;
 611                         break;
 612                 }
 613
 614                 msg += linelen;
 615                 len -= linelen;
 616                 if (hdr) {
 617                         if (linelen == 1) {
 618                                 hdr = 0;
 619                                 if ((fmt != CMIT_FMT_ONELINE) && !subject)
 620                                         buf[offset++] = '\n';
 621                                 continue;
 622                         }
 623                         if (fmt == CMIT_FMT_RAW) {
 624                                 memcpy(buf + offset, line, linelen);
 625                                 offset += linelen;
 626                                 continue;
 627                         }
 628                         if (!memcmp(line, "parent ", 7)) {
 629                                 if (linelen != 48)
 630                                         die("bad parent line in commit");
 631                                 continue;
 632                         }
 633
 634                         if (!parents_shown) {
 635                                 offset += add_merge_info(fmt, buf + offset,
 636                                                          commit, abbrev);
 637                                 parents_shown = 1;
 638                                 continue;
 639                         }
 640                         /*
 641                          * MEDIUM == DEFAULT shows only author with dates.
 642                          * FULL shows both authors but not dates.
 643                          * FULLER shows both authors and dates.
 644                          */
 645                         if (!memcmp(line, "author ", 7))
 646                                 offset += add_user_info("Author", fmt,
 647                                                         buf + offset,
 648                                                         line + 7);
 649                         if (!memcmp(line, "committer ", 10) &&
 650                             (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
 651                                 offset += add_user_info("Commit", fmt,
 652                                                         buf + offset,
 653                                                         line + 10);
 654                         continue;
 655                 }
 656
 657                 if (is_empty_line(line, &linelen)) {
 658                         if (!body)
 659                                 continue;
 660                         if (subject)
 661                                 continue;
 662                         if (fmt == CMIT_FMT_SHORT)
 663                                 break;
 664                 } else {
 665                         body = 1;
 666                 }
 667
 668                 if (subject) {
 669                         int slen = strlen(subject);
 670                         memcpy(buf + offset, subject, slen);
 671                         offset += slen;
 672                         offset += add_rfc2047(buf + offset, line, linelen);
 673                 }
 674                 else {
 675                         memset(buf + offset, ' ', indent);
 676                         memcpy(buf + offset + indent, line, linelen);
 677                         offset += linelen + indent;
 678                 }
 679                 buf[offset++] = '\n';
 680                 if (fmt == CMIT_FMT_ONELINE)
 681                         break;
 682                 if (subject && plain_non_ascii) {
 683                         static const char header[] =
 684                                 "Content-Type: text/plain; charset=UTF-8\n"
 685                                 "Content-Transfer-Encoding: 8bit\n";
 686                         memcpy(buf + offset, header, sizeof(header)-1);
 687                         offset += sizeof(header)-1;
 688                 }
 689                 if (after_subject) {
 690                         int slen = strlen(after_subject);
 691                         if (slen > space - offset - 1)
 692                                 slen = space - offset - 1;
 693                         memcpy(buf + offset, after_subject, slen);
 694                         offset += slen;
 695                         after_subject = NULL;
 696                 }
 697                 subject = NULL;
 698         }
 699         while (offset && isspace(buf[offset-1]))
 700                 offset--;
 701         /* Make sure there is an EOLN for the non-oneline case */
 702         if (fmt != CMIT_FMT_ONELINE)
 703                 buf[offset++] = '\n';
 704         buf[offset] = '\0';
 705         return offset;
 706 }
 707
 708 struct commit *pop_commit(struct commit_list **stack)
 709 {
 710         struct commit_list *top = *stack;
 711         struct commit *item = top ? top->item : NULL;
 712
 713         if (top) {
 714                 *stack = top->next;
 715                 free(top);
 716         }
 717         return item;
 718 }
 719
 720 int count_parents(struct commit * commit)
 721 {
 722         int count = 0;
 723         struct commit_list * parents = commit->parents;
 724         for (count=0;parents; parents=parents->next,count++)
 725           ;
 726         return count;
 727 }
 728
 729 void topo_sort_default_setter(struct commit *c, void *data)
 730 {
 731         c->util = data;
 732 }
 733
 734 void *topo_sort_default_getter(struct commit *c)
 735 {
 736         return c->util;
 737 }
 738
 739 /*
 740  * Performs an in-place topological sort on the list supplied.
 741  */
 742 void sort_in_topological_order(struct commit_list ** list, int lifo)
 743 {
 744         sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
 745                                      topo_sort_default_getter);
 746 }
 747
 748 void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 749                                   topo_sort_set_fn_t setter,
 750                                   topo_sort_get_fn_t getter)
 751 {
 752         struct commit_list * next = *list;
 753         struct commit_list * work = NULL, **insert;
 754         struct commit_list ** pptr = list;
 755         struct sort_node * nodes;
 756         struct sort_node * next_nodes;
 757         int count = 0;
 758
 759         /* determine the size of the list */
 760         while (next) {
 761                 next = next->next;
 762                 count++;
 763         }
 764
 765         if (!count)
 766                 return;
 767         /* allocate an array to help sort the list */
 768         nodes = xcalloc(count, sizeof(*nodes));
 769         /* link the list to the array */
 770         next_nodes = nodes;
 771         next=*list;
 772         while (next) {
 773                 next_nodes->list_item = next;
 774                 setter(next->item, next_nodes);
 775                 next_nodes++;
 776                 next = next->next;
 777         }
 778         /* update the indegree */
 779         next=*list;
 780         while (next) {
 781                 struct commit_list * parents = next->item->parents;
 782                 while (parents) {
 783                         struct commit * parent=parents->item;
 784                         struct sort_node * pn = (struct sort_node *) getter(parent);
 785
 786                         if (pn)
 787                                 pn->indegree++;
 788                         parents=parents->next;
 789                 }
 790                 next=next->next;
 791         }
 792         /*
 793          * find the tips
 794          *
 795          * tips are nodes not reachable from any other node in the list
 796          *
 797          * the tips serve as a starting set for the work queue.
 798          */
 799         next=*list;
 800         insert = &work;
 801         while (next) {
 802                 struct sort_node * node = (struct sort_node *) getter(next->item);
 803
 804                 if (node->indegree == 0) {
 805                         insert = &commit_list_insert(next->item, insert)->next;
 806                 }
 807                 next=next->next;
 808         }
 809
 810         /* process the list in topological order */
 811         if (!lifo)
 812                 sort_by_date(&work);
 813         while (work) {
 814                 struct commit * work_item = pop_commit(&work);
 815                 struct sort_node * work_node = (struct sort_node *) getter(work_item);
 816                 struct commit_list * parents = work_item->parents;
 817
 818                 while (parents) {
 819                         struct commit * parent=parents->item;
 820                         struct sort_node * pn = (struct sort_node *) getter(parent);
 821
 822                         if (pn) {
 823                                 /*
 824                                  * parents are only enqueued for emission
 825                                  * when all their children have been emitted thereby
 826                                  * guaranteeing topological order.
 827                                  */
 828                                 pn->indegree--;
 829                                 if (!pn->indegree) {
 830                                         if (!lifo)
 831                                                 insert_by_date(parent, &work);
 832                                         else
 833                                                 commit_list_insert(parent, &work);
 834                                 }
 835                         }
 836                         parents=parents->next;
 837                 }
 838                 /*
 839                  * work_item is a commit all of whose children
 840                  * have already been emitted. we can emit it now.
 841                  */
 842                 *pptr = work_node->list_item;
 843                 pptr = &(*pptr)->next;
 844                 *pptr = NULL;
 845                 setter(work_item, NULL);
 846         }
 847         free(nodes);
 848 }
 849
 850 /* merge-rebase stuff */
 851
 852 #define PARENT1 1
 853 #define PARENT2 2
 854 #define UNINTERESTING 4
 855
 856 static struct commit *interesting(struct commit_list *list)
 857 {
 858         while (list) {
 859                 struct commit *commit = list->item;
 860                 list = list->next;
 861                 if (commit->object.flags & UNINTERESTING)
 862                         continue;
 863                 return commit;
 864         }
 865         return NULL;
 866 }
 867
 868 /*
 869  * A pathological example of how this thing works.
 870  *
 871  * Suppose we had this commit graph, where chronologically
 872  * the timestamp on the commit are A <= B <= C <= D <= E <= F
 873  * and we are trying to figure out the merge base for E and F
 874  * commits.
 875  *
 876  *                  F
 877  *                 / \
 878  *            E   A   D
 879  *             \ /   /
 880  *              B   /
 881  *               \ /
 882  *                C
 883  *
 884  * First we push E and F to list to be processed.  E gets bit 1
 885  * and F gets bit 2.  The list becomes:
 886  *
 887  *     list=F(2) E(1), result=empty
 888  *
 889  * Then we pop F, the newest commit, from the list.  Its flag is 2.
 890  * We scan its parents, mark them reachable from the side that F is
 891  * reachable from, and push them to the list:
 892  *
 893  *     list=E(1) D(2) A(2), result=empty
 894  *
 895  * Next pop E and do the same.
 896  *
 897  *     list=D(2) B(1) A(2), result=empty
 898  *
 899  * Next pop D and do the same.
 900  *
 901  *     list=C(2) B(1) A(2), result=empty
 902  *
 903  * Next pop C and do the same.
 904  *
 905  *     list=B(1) A(2), result=empty
 906  *
 907  * Now it is B's turn.  We mark its parent, C, reachable from B's side,
 908  * and push it to the list:
 909  *
 910  *     list=C(3) A(2), result=empty
 911  *
 912  * Now pop C and notice it has flags==3.  It is placed on the result list,
 913  * and the list now contains:
 914  *
 915  *     list=A(2), result=C(3)
 916  *
 917  * We pop A and do the same.
 918  *
 919  *     list=B(3), result=C(3)
 920  *
 921  * Next, we pop B and something very interesting happens.  It has flags==3
 922  * so it is also placed on the result list, and its parents are marked
 923  * uninteresting, retroactively, and placed back on the list:
 924  *
 925  *    list=C(7), result=C(7) B(3)
 926  *
 927  * Now, list does not have any interesting commit.  So we find the newest
 928  * commit from the result list that is not marked uninteresting.  Which is
 929  * commit B.
 930  *
 931  *
 932  * Another pathological example how this thing used to fail to mark an
 933  * ancestor of a merge base as UNINTERESTING before we introduced the
 934  * postprocessing phase (mark_reachable_commits).
 935  *
 936  *                2
 937  *                H
 938  *          1    / \
 939  *          G   A   \
 940  *          |\ /     \
 941  *          | B       \
 942  *          |  \       \
 943  *           \  C       F
 944  *            \  \     /
 945  *             \  D   /
 946  *              \ |  /
 947  *               \| /
 948  *                E
 949  *
 950  *       list                   A B C D E F G H
 951  *       G1 H2                  - - - - - - 1 2
 952  *       H2 E1 B1               - 1 - - 1 - 1 2
 953  *       F2 E1 B1 A2            2 1 - - 1 2 1 2
 954  *       E3 B1 A2               2 1 - - 3 2 1 2
 955  *       B1 A2                  2 1 - - 3 2 1 2
 956  *       C1 A2                  2 1 1 - 3 2 1 2
 957  *       D1 A2                  2 1 1 1 3 2 1 2
 958  *       A2                     2 1 1 1 3 2 1 2
 959  *       B3                     2 3 1 1 3 2 1 2
 960  *       C7                     2 3 7 1 3 2 1 2
 961  *
 962  * At this point, unfortunately, everybody in the list is
 963  * uninteresting, so we fail to complete the following two
 964  * steps to fully marking uninteresting commits.
 965  *
 966  *       D7                     2 3 7 7 3 2 1 2
 967  *       E7                     2 3 7 7 7 2 1 2
 968  *
 969  * and we ended up showing E as an interesting merge base.
 970  * The postprocessing phase re-injects C and continues traversal
 971  * to contaminate D and E.
 972  */
 973
 974 static void mark_reachable_commits(struct commit_list *result,
 975                                    struct commit_list *list)
 976 {
 977         struct commit_list *tmp;
 978
 979         /*
 980          * Postprocess to fully contaminate the well.
 981          */
 982         for (tmp = result; tmp; tmp = tmp->next) {
 983                 struct commit *c = tmp->item;
 984                 /* Reinject uninteresting ones to list,
 985                  * so we can scan their parents.
 986                  */
 987                 if (c->object.flags & UNINTERESTING)
 988                         commit_list_insert(c, &list);
 989         }
 990         while (list) {
 991                 struct commit *c = list->item;
 992                 struct commit_list *parents;
 993
 994                 tmp = list;
 995                 list = list->next;
 996                 free(tmp);
 997
 998                 /* Anything taken out of the list is uninteresting, so
 999                  * mark all its parents uninteresting.  We do not
1000                  * parse new ones (we already parsed all the relevant
1001                  * ones).
1002                  */
1003                 parents = c->parents;
1004                 while (parents) {
1005                         struct commit *p = parents->item;
1006                         parents = parents->next;
1007                         if (!(p->object.flags & UNINTERESTING)) {
1008                                 p->object.flags |= UNINTERESTING;
1009                                 commit_list_insert(p, &list);
1010                         }
1011                 }
1012         }
1013 }
1014
1015 struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2)
1016 {
1017         struct commit_list *list = NULL;
1018         struct commit_list *result = NULL;
1019         struct commit_list *tmp = NULL;
1020
1021         if (rev1 == rev2)
1022                 return commit_list_insert(rev1, &result);
1023
1024         parse_commit(rev1);
1025         parse_commit(rev2);
1026
1027         rev1->object.flags |= PARENT1;
1028         rev2->object.flags |= PARENT2;
1029         insert_by_date(rev1, &list);
1030         insert_by_date(rev2, &list);
1031
1032         while (interesting(list)) {
1033                 struct commit *commit = list->item;
1034                 struct commit_list *parents;
1035                 int flags = commit->object.flags
1036                         & (PARENT1 | PARENT2 | UNINTERESTING);
1037
1038                 tmp = list;
1039                 list = list->next;
1040                 free(tmp);
1041                 if (flags == (PARENT1 | PARENT2)) {
1042                         insert_by_date(commit, &result);
1043
1044                         /* Mark parents of a found merge uninteresting */
1045                         flags |= UNINTERESTING;
1046                 }
1047                 parents = commit->parents;
1048                 while (parents) {
1049                         struct commit *p = parents->item;
1050                         parents = parents->next;
1051                         if ((p->object.flags & flags) == flags)
1052                                 continue;
1053                         parse_commit(p);
1054                         p->object.flags |= flags;
1055                         insert_by_date(p, &list);
1056                 }
1057         }
1058
1059         if (!result)
1060                 return NULL;
1061
1062         if (result->next && list)
1063                 mark_reachable_commits(result, list);
1064
1065         /* cull duplicates */
1066         for (tmp = result, list = NULL; tmp; ) {
1067                 struct commit *commit = tmp->item;
1068                 struct commit_list *next = tmp->next;
1069                 if (commit->object.flags & UNINTERESTING) {
1070                         if (list != NULL)
1071                                 list->next = next;
1072                         free(tmp);
1073                 } else {
1074                         if (list == NULL)
1075                                 result = tmp;
1076                         list = tmp;
1077                         commit->object.flags |= UNINTERESTING;
1078                 }
1079
1080                 tmp = next;
1081         }
1082
1083         /* reset flags */
1084         clear_commit_marks(rev1, PARENT1 | PARENT2 | UNINTERESTING);
1085         clear_commit_marks(rev2, PARENT1 | PARENT2 | UNINTERESTING);
1086
1087         return result;
1088 }