246cd18b0eb6306e8142ae349ddfd753c2c656a1
   1#include "cache.h"
   2#include "tag.h"
   3#include "commit.h"
   4#include "pkt-line.h"
   5#include "utf8.h"
   6#include "diff.h"
   7#include "revision.h"
   8#include "notes.h"
   9
  10int save_commit_buffer = 1;
  11
  12const char *commit_type = "commit";
  13
  14static struct commit *check_commit(struct object *obj,
  15                                   const unsigned char *sha1,
  16                                   int quiet)
  17{
  18        if (obj->type != OBJ_COMMIT) {
  19                if (!quiet)
  20                        error("Object %s is a %s, not a commit",
  21                              sha1_to_hex(sha1), typename(obj->type));
  22                return NULL;
  23        }
  24        return (struct commit *) obj;
  25}
  26
  27struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  28                                              int quiet)
  29{
  30        struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  31
  32        if (!obj)
  33                return NULL;
  34        return check_commit(obj, sha1, quiet);
  35}
  36
  37struct commit *lookup_commit_reference(const unsigned char *sha1)
  38{
  39        return lookup_commit_reference_gently(sha1, 0);
  40}
  41
  42struct commit *lookup_commit(const unsigned char *sha1)
  43{
  44        struct object *obj = lookup_object(sha1);
  45        if (!obj)
  46                return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  47        if (!obj->type)
  48                obj->type = OBJ_COMMIT;
  49        return check_commit(obj, sha1, 0);
  50}
  51
  52struct commit *lookup_commit_reference_by_name(const char *name)
  53{
  54        unsigned char sha1[20];
  55        struct commit *commit;
  56
  57        if (get_sha1(name, sha1))
  58                return NULL;
  59        commit = lookup_commit_reference(sha1);
  60        if (!commit || parse_commit(commit))
  61                return NULL;
  62        return commit;
  63}
  64
  65static unsigned long parse_commit_date(const char *buf, const char *tail)
  66{
  67        const char *dateptr;
  68
  69        if (buf + 6 >= tail)
  70                return 0;
  71        if (memcmp(buf, "author", 6))
  72                return 0;
  73        while (buf < tail && *buf++ != '\n')
  74                /* nada */;
  75        if (buf + 9 >= tail)
  76                return 0;
  77        if (memcmp(buf, "committer", 9))
  78                return 0;
  79        while (buf < tail && *buf++ != '>')
  80                /* nada */;
  81        if (buf >= tail)
  82                return 0;
  83        dateptr = buf;
  84        while (buf < tail && *buf++ != '\n')
  85                /* nada */;
  86        if (buf >= tail)
  87                return 0;
  88        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
  89        return strtoul(dateptr, NULL, 10);
  90}
  91
  92static struct commit_graft **commit_graft;
  93static int commit_graft_alloc, commit_graft_nr;
  94
  95static int commit_graft_pos(const unsigned char *sha1)
  96{
  97        int lo, hi;
  98        lo = 0;
  99        hi = commit_graft_nr;
 100        while (lo < hi) {
 101                int mi = (lo + hi) / 2;
 102                struct commit_graft *graft = commit_graft[mi];
 103                int cmp = hashcmp(sha1, graft->sha1);
 104                if (!cmp)
 105                        return mi;
 106                if (cmp < 0)
 107                        hi = mi;
 108                else
 109                        lo = mi + 1;
 110        }
 111        return -lo - 1;
 112}
 113
 114int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 115{
 116        int pos = commit_graft_pos(graft->sha1);
 117
 118        if (0 <= pos) {
 119                if (ignore_dups)
 120                        free(graft);
 121                else {
 122                        free(commit_graft[pos]);
 123                        commit_graft[pos] = graft;
 124                }
 125                return 1;
 126        }
 127        pos = -pos - 1;
 128        if (commit_graft_alloc <= ++commit_graft_nr) {
 129                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 130                commit_graft = xrealloc(commit_graft,
 131                                        sizeof(*commit_graft) *
 132                                        commit_graft_alloc);
 133        }
 134        if (pos < commit_graft_nr)
 135                memmove(commit_graft + pos + 1,
 136                        commit_graft + pos,
 137                        (commit_graft_nr - pos - 1) *
 138                        sizeof(*commit_graft));
 139        commit_graft[pos] = graft;
 140        return 0;
 141}
 142
 143struct commit_graft *read_graft_line(char *buf, int len)
 144{
 145        /* The format is just "Commit Parent1 Parent2 ...\n" */
 146        int i;
 147        struct commit_graft *graft = NULL;
 148
 149        while (len && isspace(buf[len-1]))
 150                buf[--len] = '\0';
 151        if (buf[0] == '#' || buf[0] == '\0')
 152                return NULL;
 153        if ((len + 1) % 41)
 154                goto bad_graft_data;
 155        i = (len + 1) / 41 - 1;
 156        graft = xmalloc(sizeof(*graft) + 20 * i);
 157        graft->nr_parent = i;
 158        if (get_sha1_hex(buf, graft->sha1))
 159                goto bad_graft_data;
 160        for (i = 40; i < len; i += 41) {
 161                if (buf[i] != ' ')
 162                        goto bad_graft_data;
 163                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 164                        goto bad_graft_data;
 165        }
 166        return graft;
 167
 168bad_graft_data:
 169        error("bad graft data: %s", buf);
 170        free(graft);
 171        return NULL;
 172}
 173
 174static int read_graft_file(const char *graft_file)
 175{
 176        FILE *fp = fopen(graft_file, "r");
 177        char buf[1024];
 178        if (!fp)
 179                return -1;
 180        while (fgets(buf, sizeof(buf), fp)) {
 181                /* The format is just "Commit Parent1 Parent2 ...\n" */
 182                int len = strlen(buf);
 183                struct commit_graft *graft = read_graft_line(buf, len);
 184                if (!graft)
 185                        continue;
 186                if (register_commit_graft(graft, 1))
 187                        error("duplicate graft data: %s", buf);
 188        }
 189        fclose(fp);
 190        return 0;
 191}
 192
 193static void prepare_commit_graft(void)
 194{
 195        static int commit_graft_prepared;
 196        char *graft_file;
 197
 198        if (commit_graft_prepared)
 199                return;
 200        graft_file = get_graft_file();
 201        read_graft_file(graft_file);
 202        /* make sure shallows are read */
 203        is_repository_shallow();
 204        commit_graft_prepared = 1;
 205}
 206
 207struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 208{
 209        int pos;
 210        prepare_commit_graft();
 211        pos = commit_graft_pos(sha1);
 212        if (pos < 0)
 213                return NULL;
 214        return commit_graft[pos];
 215}
 216
 217int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 218{
 219        int i, ret;
 220        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 221                ret = fn(commit_graft[i], cb_data);
 222        return ret;
 223}
 224
 225int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
 226{
 227        int i, count = 0;
 228        for (i = 0; i < commit_graft_nr; i++)
 229                if (commit_graft[i]->nr_parent < 0) {
 230                        const char *hex =
 231                                sha1_to_hex(commit_graft[i]->sha1);
 232                        count++;
 233                        if (use_pack_protocol)
 234                                packet_buf_write(out, "shallow %s", hex);
 235                        else {
 236                                strbuf_addstr(out, hex);
 237                                strbuf_addch(out, '\n');
 238                        }
 239                }
 240        return count;
 241}
 242
 243int unregister_shallow(const unsigned char *sha1)
 244{
 245        int pos = commit_graft_pos(sha1);
 246        if (pos < 0)
 247                return -1;
 248        if (pos + 1 < commit_graft_nr)
 249                memmove(commit_graft + pos, commit_graft + pos + 1,
 250                                sizeof(struct commit_graft *)
 251                                * (commit_graft_nr - pos - 1));
 252        commit_graft_nr--;
 253        return 0;
 254}
 255
 256int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 257{
 258        const char *tail = buffer;
 259        const char *bufptr = buffer;
 260        unsigned char parent[20];
 261        struct commit_list **pptr;
 262        struct commit_graft *graft;
 263
 264        if (item->object.parsed)
 265                return 0;
 266        item->object.parsed = 1;
 267        tail += size;
 268        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 269                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 270        if (get_sha1_hex(bufptr + 5, parent) < 0)
 271                return error("bad tree pointer in commit %s",
 272                             sha1_to_hex(item->object.sha1));
 273        item->tree = lookup_tree(parent);
 274        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 275        pptr = &item->parents;
 276
 277        graft = lookup_commit_graft(item->object.sha1);
 278        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 279                struct commit *new_parent;
 280
 281                if (tail <= bufptr + 48 ||
 282                    get_sha1_hex(bufptr + 7, parent) ||
 283                    bufptr[47] != '\n')
 284                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 285                bufptr += 48;
 286                /*
 287                 * The clone is shallow if nr_parent < 0, and we must
 288                 * not traverse its real parents even when we unhide them.
 289                 */
 290                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 291                        continue;
 292                new_parent = lookup_commit(parent);
 293                if (new_parent)
 294                        pptr = &commit_list_insert(new_parent, pptr)->next;
 295        }
 296        if (graft) {
 297                int i;
 298                struct commit *new_parent;
 299                for (i = 0; i < graft->nr_parent; i++) {
 300                        new_parent = lookup_commit(graft->parent[i]);
 301                        if (!new_parent)
 302                                continue;
 303                        pptr = &commit_list_insert(new_parent, pptr)->next;
 304                }
 305        }
 306        item->date = parse_commit_date(bufptr, tail);
 307
 308        return 0;
 309}
 310
 311int parse_commit(struct commit *item)
 312{
 313        enum object_type type;
 314        void *buffer;
 315        unsigned long size;
 316        int ret;
 317
 318        if (!item)
 319                return -1;
 320        if (item->object.parsed)
 321                return 0;
 322        buffer = read_sha1_file(item->object.sha1, &type, &size);
 323        if (!buffer)
 324                return error("Could not read %s",
 325                             sha1_to_hex(item->object.sha1));
 326        if (type != OBJ_COMMIT) {
 327                free(buffer);
 328                return error("Object %s not a commit",
 329                             sha1_to_hex(item->object.sha1));
 330        }
 331        ret = parse_commit_buffer(item, buffer, size);
 332        if (save_commit_buffer && !ret) {
 333                item->buffer = buffer;
 334                return 0;
 335        }
 336        free(buffer);
 337        return ret;
 338}
 339
 340int find_commit_subject(const char *commit_buffer, const char **subject)
 341{
 342        const char *eol;
 343        const char *p = commit_buffer;
 344
 345        while (*p && (*p != '\n' || p[1] != '\n'))
 346                p++;
 347        if (*p) {
 348                p += 2;
 349                for (eol = p; *eol && *eol != '\n'; eol++)
 350                        ; /* do nothing */
 351        } else
 352                eol = p;
 353
 354        *subject = p;
 355
 356        return eol - p;
 357}
 358
 359struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 360{
 361        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 362        new_list->item = item;
 363        new_list->next = *list_p;
 364        *list_p = new_list;
 365        return new_list;
 366}
 367
 368unsigned commit_list_count(const struct commit_list *l)
 369{
 370        unsigned c = 0;
 371        for (; l; l = l->next )
 372                c++;
 373        return c;
 374}
 375
 376void free_commit_list(struct commit_list *list)
 377{
 378        while (list) {
 379                struct commit_list *temp = list;
 380                list = temp->next;
 381                free(temp);
 382        }
 383}
 384
 385struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 386{
 387        struct commit_list **pp = list;
 388        struct commit_list *p;
 389        while ((p = *pp) != NULL) {
 390                if (p->item->date < item->date) {
 391                        break;
 392                }
 393                pp = &p->next;
 394        }
 395        return commit_list_insert(item, pp);
 396}
 397
 398
 399void commit_list_sort_by_date(struct commit_list **list)
 400{
 401        struct commit_list *ret = NULL;
 402        while (*list) {
 403                commit_list_insert_by_date((*list)->item, &ret);
 404                *list = (*list)->next;
 405        }
 406        *list = ret;
 407}
 408
 409struct commit *pop_most_recent_commit(struct commit_list **list,
 410                                      unsigned int mark)
 411{
 412        struct commit *ret = (*list)->item;
 413        struct commit_list *parents = ret->parents;
 414        struct commit_list *old = *list;
 415
 416        *list = (*list)->next;
 417        free(old);
 418
 419        while (parents) {
 420                struct commit *commit = parents->item;
 421                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 422                        commit->object.flags |= mark;
 423                        commit_list_insert_by_date(commit, list);
 424                }
 425                parents = parents->next;
 426        }
 427        return ret;
 428}
 429
 430void clear_commit_marks(struct commit *commit, unsigned int mark)
 431{
 432        while (commit) {
 433                struct commit_list *parents;
 434
 435                if (!(mark & commit->object.flags))
 436                        return;
 437
 438                commit->object.flags &= ~mark;
 439
 440                parents = commit->parents;
 441                if (!parents)
 442                        return;
 443
 444                while ((parents = parents->next))
 445                        clear_commit_marks(parents->item, mark);
 446
 447                commit = commit->parents->item;
 448        }
 449}
 450
 451struct commit *pop_commit(struct commit_list **stack)
 452{
 453        struct commit_list *top = *stack;
 454        struct commit *item = top ? top->item : NULL;
 455
 456        if (top) {
 457                *stack = top->next;
 458                free(top);
 459        }
 460        return item;
 461}
 462
 463/*
 464 * Performs an in-place topological sort on the list supplied.
 465 */
 466void sort_in_topological_order(struct commit_list ** list, int lifo)
 467{
 468        struct commit_list *next, *orig = *list;
 469        struct commit_list *work, **insert;
 470        struct commit_list **pptr;
 471
 472        if (!orig)
 473                return;
 474        *list = NULL;
 475
 476        /* Mark them and clear the indegree */
 477        for (next = orig; next; next = next->next) {
 478                struct commit *commit = next->item;
 479                commit->indegree = 1;
 480        }
 481
 482        /* update the indegree */
 483        for (next = orig; next; next = next->next) {
 484                struct commit_list * parents = next->item->parents;
 485                while (parents) {
 486                        struct commit *parent = parents->item;
 487
 488                        if (parent->indegree)
 489                                parent->indegree++;
 490                        parents = parents->next;
 491                }
 492        }
 493
 494        /*
 495         * find the tips
 496         *
 497         * tips are nodes not reachable from any other node in the list
 498         *
 499         * the tips serve as a starting set for the work queue.
 500         */
 501        work = NULL;
 502        insert = &work;
 503        for (next = orig; next; next = next->next) {
 504                struct commit *commit = next->item;
 505
 506                if (commit->indegree == 1)
 507                        insert = &commit_list_insert(commit, insert)->next;
 508        }
 509
 510        /* process the list in topological order */
 511        if (!lifo)
 512                commit_list_sort_by_date(&work);
 513
 514        pptr = list;
 515        *list = NULL;
 516        while (work) {
 517                struct commit *commit;
 518                struct commit_list *parents, *work_item;
 519
 520                work_item = work;
 521                work = work_item->next;
 522                work_item->next = NULL;
 523
 524                commit = work_item->item;
 525                for (parents = commit->parents; parents ; parents = parents->next) {
 526                        struct commit *parent=parents->item;
 527
 528                        if (!parent->indegree)
 529                                continue;
 530
 531                        /*
 532                         * parents are only enqueued for emission
 533                         * when all their children have been emitted thereby
 534                         * guaranteeing topological order.
 535                         */
 536                        if (--parent->indegree == 1) {
 537                                if (!lifo)
 538                                        commit_list_insert_by_date(parent, &work);
 539                                else
 540                                        commit_list_insert(parent, &work);
 541                        }
 542                }
 543                /*
 544                 * work_item is a commit all of whose children
 545                 * have already been emitted. we can emit it now.
 546                 */
 547                commit->indegree = 0;
 548                *pptr = work_item;
 549                pptr = &work_item->next;
 550        }
 551}
 552
 553/* merge-base stuff */
 554
 555/* bits #0..15 in revision.h */
 556#define PARENT1         (1u<<16)
 557#define PARENT2         (1u<<17)
 558#define STALE           (1u<<18)
 559#define RESULT          (1u<<19)
 560
 561static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 562
 563static struct commit *interesting(struct commit_list *list)
 564{
 565        while (list) {
 566                struct commit *commit = list->item;
 567                list = list->next;
 568                if (commit->object.flags & STALE)
 569                        continue;
 570                return commit;
 571        }
 572        return NULL;
 573}
 574
 575static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 576{
 577        struct commit_list *list = NULL;
 578        struct commit_list *result = NULL;
 579        int i;
 580
 581        for (i = 0; i < n; i++) {
 582                if (one == twos[i])
 583                        /*
 584                         * We do not mark this even with RESULT so we do not
 585                         * have to clean it up.
 586                         */
 587                        return commit_list_insert(one, &result);
 588        }
 589
 590        if (parse_commit(one))
 591                return NULL;
 592        for (i = 0; i < n; i++) {
 593                if (parse_commit(twos[i]))
 594                        return NULL;
 595        }
 596
 597        one->object.flags |= PARENT1;
 598        commit_list_insert_by_date(one, &list);
 599        for (i = 0; i < n; i++) {
 600                twos[i]->object.flags |= PARENT2;
 601                commit_list_insert_by_date(twos[i], &list);
 602        }
 603
 604        while (interesting(list)) {
 605                struct commit *commit;
 606                struct commit_list *parents;
 607                struct commit_list *next;
 608                int flags;
 609
 610                commit = list->item;
 611                next = list->next;
 612                free(list);
 613                list = next;
 614
 615                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 616                if (flags == (PARENT1 | PARENT2)) {
 617                        if (!(commit->object.flags & RESULT)) {
 618                                commit->object.flags |= RESULT;
 619                                commit_list_insert_by_date(commit, &result);
 620                        }
 621                        /* Mark parents of a found merge stale */
 622                        flags |= STALE;
 623                }
 624                parents = commit->parents;
 625                while (parents) {
 626                        struct commit *p = parents->item;
 627                        parents = parents->next;
 628                        if ((p->object.flags & flags) == flags)
 629                                continue;
 630                        if (parse_commit(p))
 631                                return NULL;
 632                        p->object.flags |= flags;
 633                        commit_list_insert_by_date(p, &list);
 634                }
 635        }
 636
 637        /* Clean up the result to remove stale ones */
 638        free_commit_list(list);
 639        list = result; result = NULL;
 640        while (list) {
 641                struct commit_list *next = list->next;
 642                if (!(list->item->object.flags & STALE))
 643                        commit_list_insert_by_date(list->item, &result);
 644                free(list);
 645                list = next;
 646        }
 647        return result;
 648}
 649
 650struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 651{
 652        struct commit_list *i, *j, *k, *ret = NULL;
 653        struct commit_list **pptr = &ret;
 654
 655        for (i = in; i; i = i->next) {
 656                if (!ret)
 657                        pptr = &commit_list_insert(i->item, pptr)->next;
 658                else {
 659                        struct commit_list *new = NULL, *end = NULL;
 660
 661                        for (j = ret; j; j = j->next) {
 662                                struct commit_list *bases;
 663                                bases = get_merge_bases(i->item, j->item, 1);
 664                                if (!new)
 665                                        new = bases;
 666                                else
 667                                        end->next = bases;
 668                                for (k = bases; k; k = k->next)
 669                                        end = k;
 670                        }
 671                        ret = new;
 672                }
 673        }
 674        return ret;
 675}
 676
 677struct commit_list *get_merge_bases_many(struct commit *one,
 678                                         int n,
 679                                         struct commit **twos,
 680                                         int cleanup)
 681{
 682        struct commit_list *list;
 683        struct commit **rslt;
 684        struct commit_list *result;
 685        int cnt, i, j;
 686
 687        result = merge_bases_many(one, n, twos);
 688        for (i = 0; i < n; i++) {
 689                if (one == twos[i])
 690                        return result;
 691        }
 692        if (!result || !result->next) {
 693                if (cleanup) {
 694                        clear_commit_marks(one, all_flags);
 695                        for (i = 0; i < n; i++)
 696                                clear_commit_marks(twos[i], all_flags);
 697                }
 698                return result;
 699        }
 700
 701        /* There are more than one */
 702        cnt = 0;
 703        list = result;
 704        while (list) {
 705                list = list->next;
 706                cnt++;
 707        }
 708        rslt = xcalloc(cnt, sizeof(*rslt));
 709        for (list = result, i = 0; list; list = list->next)
 710                rslt[i++] = list->item;
 711        free_commit_list(result);
 712
 713        clear_commit_marks(one, all_flags);
 714        for (i = 0; i < n; i++)
 715                clear_commit_marks(twos[i], all_flags);
 716        for (i = 0; i < cnt - 1; i++) {
 717                for (j = i+1; j < cnt; j++) {
 718                        if (!rslt[i] || !rslt[j])
 719                                continue;
 720                        result = merge_bases_many(rslt[i], 1, &rslt[j]);
 721                        clear_commit_marks(rslt[i], all_flags);
 722                        clear_commit_marks(rslt[j], all_flags);
 723                        for (list = result; list; list = list->next) {
 724                                if (rslt[i] == list->item)
 725                                        rslt[i] = NULL;
 726                                if (rslt[j] == list->item)
 727                                        rslt[j] = NULL;
 728                        }
 729                }
 730        }
 731
 732        /* Surviving ones in rslt[] are the independent results */
 733        result = NULL;
 734        for (i = 0; i < cnt; i++) {
 735                if (rslt[i])
 736                        commit_list_insert_by_date(rslt[i], &result);
 737        }
 738        free(rslt);
 739        return result;
 740}
 741
 742struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 743                                    int cleanup)
 744{
 745        return get_merge_bases_many(one, 1, &two, cleanup);
 746}
 747
 748int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 749{
 750        if (!with_commit)
 751                return 1;
 752        while (with_commit) {
 753                struct commit *other;
 754
 755                other = with_commit->item;
 756                with_commit = with_commit->next;
 757                if (in_merge_bases(other, &commit, 1))
 758                        return 1;
 759        }
 760        return 0;
 761}
 762
 763int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 764{
 765        struct commit_list *bases, *b;
 766        int ret = 0;
 767
 768        if (num == 1)
 769                bases = get_merge_bases(commit, *reference, 1);
 770        else
 771                die("not yet");
 772        for (b = bases; b; b = b->next) {
 773                if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 774                        ret = 1;
 775                        break;
 776                }
 777        }
 778
 779        free_commit_list(bases);
 780        return ret;
 781}
 782
 783struct commit_list *reduce_heads(struct commit_list *heads)
 784{
 785        struct commit_list *p;
 786        struct commit_list *result = NULL, **tail = &result;
 787        struct commit **other;
 788        size_t num_head, num_other;
 789
 790        if (!heads)
 791                return NULL;
 792
 793        /* Avoid unnecessary reallocations */
 794        for (p = heads, num_head = 0; p; p = p->next)
 795                num_head++;
 796        other = xcalloc(sizeof(*other), num_head);
 797
 798        /* For each commit, see if it can be reached by others */
 799        for (p = heads; p; p = p->next) {
 800                struct commit_list *q, *base;
 801
 802                /* Do we already have this in the result? */
 803                for (q = result; q; q = q->next)
 804                        if (p->item == q->item)
 805                                break;
 806                if (q)
 807                        continue;
 808
 809                num_other = 0;
 810                for (q = heads; q; q = q->next) {
 811                        if (p->item == q->item)
 812                                continue;
 813                        other[num_other++] = q->item;
 814                }
 815                if (num_other)
 816                        base = get_merge_bases_many(p->item, num_other, other, 1);
 817                else
 818                        base = NULL;
 819                /*
 820                 * If p->item does not have anything common with other
 821                 * commits, there won't be any merge base.  If it is
 822                 * reachable from some of the others, p->item will be
 823                 * the merge base.  If its history is connected with
 824                 * others, but p->item is not reachable by others, we
 825                 * will get something other than p->item back.
 826                 */
 827                if (!base || (base->item != p->item))
 828                        tail = &(commit_list_insert(p->item, tail)->next);
 829                free_commit_list(base);
 830        }
 831        free(other);
 832        return result;
 833}
 834
 835static const char commit_utf8_warn[] =
 836"Warning: commit message does not conform to UTF-8.\n"
 837"You may want to amend it after fixing the message, or set the config\n"
 838"variable i18n.commitencoding to the encoding your project uses.\n";
 839
 840int commit_tree(const char *msg, unsigned char *tree,
 841                struct commit_list *parents, unsigned char *ret,
 842                const char *author)
 843{
 844        int result;
 845        int encoding_is_utf8;
 846        struct strbuf buffer;
 847
 848        assert_sha1_type(tree, OBJ_TREE);
 849
 850        /* Not having i18n.commitencoding is the same as having utf-8 */
 851        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
 852
 853        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
 854        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
 855
 856        /*
 857         * NOTE! This ordering means that the same exact tree merged with a
 858         * different order of parents will be a _different_ changeset even
 859         * if everything else stays the same.
 860         */
 861        while (parents) {
 862                struct commit_list *next = parents->next;
 863                strbuf_addf(&buffer, "parent %s\n",
 864                        sha1_to_hex(parents->item->object.sha1));
 865                free(parents);
 866                parents = next;
 867        }
 868
 869        /* Person/date information */
 870        if (!author)
 871                author = git_author_info(IDENT_ERROR_ON_NO_NAME);
 872        strbuf_addf(&buffer, "author %s\n", author);
 873        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
 874        if (!encoding_is_utf8)
 875                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
 876        strbuf_addch(&buffer, '\n');
 877
 878        /* And add the comment */
 879        strbuf_addstr(&buffer, msg);
 880
 881        /* And check the encoding */
 882        if (encoding_is_utf8 && !is_utf8(buffer.buf))
 883                fprintf(stderr, commit_utf8_warn);
 884
 885        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
 886        strbuf_release(&buffer);
 887        return result;
 888}