commit.con commit Merge branch 'jn/merge-renormalize' (8aed4a5)
   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
  52static unsigned long parse_commit_date(const char *buf, const char *tail)
  53{
  54        const char *dateptr;
  55
  56        if (buf + 6 >= tail)
  57                return 0;
  58        if (memcmp(buf, "author", 6))
  59                return 0;
  60        while (buf < tail && *buf++ != '\n')
  61                /* nada */;
  62        if (buf + 9 >= tail)
  63                return 0;
  64        if (memcmp(buf, "committer", 9))
  65                return 0;
  66        while (buf < tail && *buf++ != '>')
  67                /* nada */;
  68        if (buf >= tail)
  69                return 0;
  70        dateptr = buf;
  71        while (buf < tail && *buf++ != '\n')
  72                /* nada */;
  73        if (buf >= tail)
  74                return 0;
  75        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
  76        return strtoul(dateptr, NULL, 10);
  77}
  78
  79static struct commit_graft **commit_graft;
  80static int commit_graft_alloc, commit_graft_nr;
  81
  82static int commit_graft_pos(const unsigned char *sha1)
  83{
  84        int lo, hi;
  85        lo = 0;
  86        hi = commit_graft_nr;
  87        while (lo < hi) {
  88                int mi = (lo + hi) / 2;
  89                struct commit_graft *graft = commit_graft[mi];
  90                int cmp = hashcmp(sha1, graft->sha1);
  91                if (!cmp)
  92                        return mi;
  93                if (cmp < 0)
  94                        hi = mi;
  95                else
  96                        lo = mi + 1;
  97        }
  98        return -lo - 1;
  99}
 100
 101int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 102{
 103        int pos = commit_graft_pos(graft->sha1);
 104
 105        if (0 <= pos) {
 106                if (ignore_dups)
 107                        free(graft);
 108                else {
 109                        free(commit_graft[pos]);
 110                        commit_graft[pos] = graft;
 111                }
 112                return 1;
 113        }
 114        pos = -pos - 1;
 115        if (commit_graft_alloc <= ++commit_graft_nr) {
 116                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 117                commit_graft = xrealloc(commit_graft,
 118                                        sizeof(*commit_graft) *
 119                                        commit_graft_alloc);
 120        }
 121        if (pos < commit_graft_nr)
 122                memmove(commit_graft + pos + 1,
 123                        commit_graft + pos,
 124                        (commit_graft_nr - pos - 1) *
 125                        sizeof(*commit_graft));
 126        commit_graft[pos] = graft;
 127        return 0;
 128}
 129
 130struct commit_graft *read_graft_line(char *buf, int len)
 131{
 132        /* The format is just "Commit Parent1 Parent2 ...\n" */
 133        int i;
 134        struct commit_graft *graft = NULL;
 135
 136        while (len && isspace(buf[len-1]))
 137                buf[--len] = '\0';
 138        if (buf[0] == '#' || buf[0] == '\0')
 139                return NULL;
 140        if ((len + 1) % 41) {
 141        bad_graft_data:
 142                error("bad graft data: %s", buf);
 143                free(graft);
 144                return NULL;
 145        }
 146        i = (len + 1) / 41 - 1;
 147        graft = xmalloc(sizeof(*graft) + 20 * i);
 148        graft->nr_parent = i;
 149        if (get_sha1_hex(buf, graft->sha1))
 150                goto bad_graft_data;
 151        for (i = 40; i < len; i += 41) {
 152                if (buf[i] != ' ')
 153                        goto bad_graft_data;
 154                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 155                        goto bad_graft_data;
 156        }
 157        return graft;
 158}
 159
 160static int read_graft_file(const char *graft_file)
 161{
 162        FILE *fp = fopen(graft_file, "r");
 163        char buf[1024];
 164        if (!fp)
 165                return -1;
 166        while (fgets(buf, sizeof(buf), fp)) {
 167                /* The format is just "Commit Parent1 Parent2 ...\n" */
 168                int len = strlen(buf);
 169                struct commit_graft *graft = read_graft_line(buf, len);
 170                if (!graft)
 171                        continue;
 172                if (register_commit_graft(graft, 1))
 173                        error("duplicate graft data: %s", buf);
 174        }
 175        fclose(fp);
 176        return 0;
 177}
 178
 179static void prepare_commit_graft(void)
 180{
 181        static int commit_graft_prepared;
 182        char *graft_file;
 183
 184        if (commit_graft_prepared)
 185                return;
 186        graft_file = get_graft_file();
 187        read_graft_file(graft_file);
 188        /* make sure shallows are read */
 189        is_repository_shallow();
 190        commit_graft_prepared = 1;
 191}
 192
 193struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 194{
 195        int pos;
 196        prepare_commit_graft();
 197        pos = commit_graft_pos(sha1);
 198        if (pos < 0)
 199                return NULL;
 200        return commit_graft[pos];
 201}
 202
 203int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
 204{
 205        int i, count = 0;
 206        for (i = 0; i < commit_graft_nr; i++)
 207                if (commit_graft[i]->nr_parent < 0) {
 208                        const char *hex =
 209                                sha1_to_hex(commit_graft[i]->sha1);
 210                        count++;
 211                        if (use_pack_protocol)
 212                                packet_buf_write(out, "shallow %s", hex);
 213                        else {
 214                                strbuf_addstr(out, hex);
 215                                strbuf_addch(out, '\n');
 216                        }
 217                }
 218        return count;
 219}
 220
 221int unregister_shallow(const unsigned char *sha1)
 222{
 223        int pos = commit_graft_pos(sha1);
 224        if (pos < 0)
 225                return -1;
 226        if (pos + 1 < commit_graft_nr)
 227                memmove(commit_graft + pos, commit_graft + pos + 1,
 228                                sizeof(struct commit_graft *)
 229                                * (commit_graft_nr - pos - 1));
 230        commit_graft_nr--;
 231        return 0;
 232}
 233
 234int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 235{
 236        char *tail = buffer;
 237        char *bufptr = buffer;
 238        unsigned char parent[20];
 239        struct commit_list **pptr;
 240        struct commit_graft *graft;
 241
 242        if (item->object.parsed)
 243                return 0;
 244        item->object.parsed = 1;
 245        tail += size;
 246        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 247                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 248        if (get_sha1_hex(bufptr + 5, parent) < 0)
 249                return error("bad tree pointer in commit %s",
 250                             sha1_to_hex(item->object.sha1));
 251        item->tree = lookup_tree(parent);
 252        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 253        pptr = &item->parents;
 254
 255        graft = lookup_commit_graft(item->object.sha1);
 256        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 257                struct commit *new_parent;
 258
 259                if (tail <= bufptr + 48 ||
 260                    get_sha1_hex(bufptr + 7, parent) ||
 261                    bufptr[47] != '\n')
 262                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 263                bufptr += 48;
 264                /*
 265                 * The clone is shallow if nr_parent < 0, and we must
 266                 * not traverse its real parents even when we unhide them.
 267                 */
 268                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 269                        continue;
 270                new_parent = lookup_commit(parent);
 271                if (new_parent)
 272                        pptr = &commit_list_insert(new_parent, pptr)->next;
 273        }
 274        if (graft) {
 275                int i;
 276                struct commit *new_parent;
 277                for (i = 0; i < graft->nr_parent; i++) {
 278                        new_parent = lookup_commit(graft->parent[i]);
 279                        if (!new_parent)
 280                                continue;
 281                        pptr = &commit_list_insert(new_parent, pptr)->next;
 282                }
 283        }
 284        item->date = parse_commit_date(bufptr, tail);
 285
 286        return 0;
 287}
 288
 289int parse_commit(struct commit *item)
 290{
 291        enum object_type type;
 292        void *buffer;
 293        unsigned long size;
 294        int ret;
 295
 296        if (!item)
 297                return -1;
 298        if (item->object.parsed)
 299                return 0;
 300        buffer = read_sha1_file(item->object.sha1, &type, &size);
 301        if (!buffer)
 302                return error("Could not read %s",
 303                             sha1_to_hex(item->object.sha1));
 304        if (type != OBJ_COMMIT) {
 305                free(buffer);
 306                return error("Object %s not a commit",
 307                             sha1_to_hex(item->object.sha1));
 308        }
 309        ret = parse_commit_buffer(item, buffer, size);
 310        if (save_commit_buffer && !ret) {
 311                item->buffer = buffer;
 312                return 0;
 313        }
 314        free(buffer);
 315        return ret;
 316}
 317
 318int find_commit_subject(const char *commit_buffer, const char **subject)
 319{
 320        const char *eol;
 321        const char *p = commit_buffer;
 322
 323        while (*p && (*p != '\n' || p[1] != '\n'))
 324                p++;
 325        if (*p) {
 326                p += 2;
 327                for (eol = p; *eol && *eol != '\n'; eol++)
 328                        ; /* do nothing */
 329        } else
 330                eol = p;
 331
 332        *subject = p;
 333
 334        return eol - p;
 335}
 336
 337struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 338{
 339        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 340        new_list->item = item;
 341        new_list->next = *list_p;
 342        *list_p = new_list;
 343        return new_list;
 344}
 345
 346unsigned commit_list_count(const struct commit_list *l)
 347{
 348        unsigned c = 0;
 349        for (; l; l = l->next )
 350                c++;
 351        return c;
 352}
 353
 354void free_commit_list(struct commit_list *list)
 355{
 356        while (list) {
 357                struct commit_list *temp = list;
 358                list = temp->next;
 359                free(temp);
 360        }
 361}
 362
 363struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 364{
 365        struct commit_list **pp = list;
 366        struct commit_list *p;
 367        while ((p = *pp) != NULL) {
 368                if (p->item->date < item->date) {
 369                        break;
 370                }
 371                pp = &p->next;
 372        }
 373        return commit_list_insert(item, pp);
 374}
 375
 376
 377void sort_by_date(struct commit_list **list)
 378{
 379        struct commit_list *ret = NULL;
 380        while (*list) {
 381                insert_by_date((*list)->item, &ret);
 382                *list = (*list)->next;
 383        }
 384        *list = ret;
 385}
 386
 387struct commit *pop_most_recent_commit(struct commit_list **list,
 388                                      unsigned int mark)
 389{
 390        struct commit *ret = (*list)->item;
 391        struct commit_list *parents = ret->parents;
 392        struct commit_list *old = *list;
 393
 394        *list = (*list)->next;
 395        free(old);
 396
 397        while (parents) {
 398                struct commit *commit = parents->item;
 399                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 400                        commit->object.flags |= mark;
 401                        insert_by_date(commit, list);
 402                }
 403                parents = parents->next;
 404        }
 405        return ret;
 406}
 407
 408void clear_commit_marks(struct commit *commit, unsigned int mark)
 409{
 410        while (commit) {
 411                struct commit_list *parents;
 412
 413                if (!(mark & commit->object.flags))
 414                        return;
 415
 416                commit->object.flags &= ~mark;
 417
 418                parents = commit->parents;
 419                if (!parents)
 420                        return;
 421
 422                while ((parents = parents->next))
 423                        clear_commit_marks(parents->item, mark);
 424
 425                commit = commit->parents->item;
 426        }
 427}
 428
 429struct commit *pop_commit(struct commit_list **stack)
 430{
 431        struct commit_list *top = *stack;
 432        struct commit *item = top ? top->item : NULL;
 433
 434        if (top) {
 435                *stack = top->next;
 436                free(top);
 437        }
 438        return item;
 439}
 440
 441/*
 442 * Performs an in-place topological sort on the list supplied.
 443 */
 444void sort_in_topological_order(struct commit_list ** list, int lifo)
 445{
 446        struct commit_list *next, *orig = *list;
 447        struct commit_list *work, **insert;
 448        struct commit_list **pptr;
 449
 450        if (!orig)
 451                return;
 452        *list = NULL;
 453
 454        /* Mark them and clear the indegree */
 455        for (next = orig; next; next = next->next) {
 456                struct commit *commit = next->item;
 457                commit->indegree = 1;
 458        }
 459
 460        /* update the indegree */
 461        for (next = orig; next; next = next->next) {
 462                struct commit_list * parents = next->item->parents;
 463                while (parents) {
 464                        struct commit *parent = parents->item;
 465
 466                        if (parent->indegree)
 467                                parent->indegree++;
 468                        parents = parents->next;
 469                }
 470        }
 471
 472        /*
 473         * find the tips
 474         *
 475         * tips are nodes not reachable from any other node in the list
 476         *
 477         * the tips serve as a starting set for the work queue.
 478         */
 479        work = NULL;
 480        insert = &work;
 481        for (next = orig; next; next = next->next) {
 482                struct commit *commit = next->item;
 483
 484                if (commit->indegree == 1)
 485                        insert = &commit_list_insert(commit, insert)->next;
 486        }
 487
 488        /* process the list in topological order */
 489        if (!lifo)
 490                sort_by_date(&work);
 491
 492        pptr = list;
 493        *list = NULL;
 494        while (work) {
 495                struct commit *commit;
 496                struct commit_list *parents, *work_item;
 497
 498                work_item = work;
 499                work = work_item->next;
 500                work_item->next = NULL;
 501
 502                commit = work_item->item;
 503                for (parents = commit->parents; parents ; parents = parents->next) {
 504                        struct commit *parent=parents->item;
 505
 506                        if (!parent->indegree)
 507                                continue;
 508
 509                        /*
 510                         * parents are only enqueued for emission
 511                         * when all their children have been emitted thereby
 512                         * guaranteeing topological order.
 513                         */
 514                        if (--parent->indegree == 1) {
 515                                if (!lifo)
 516                                        insert_by_date(parent, &work);
 517                                else
 518                                        commit_list_insert(parent, &work);
 519                        }
 520                }
 521                /*
 522                 * work_item is a commit all of whose children
 523                 * have already been emitted. we can emit it now.
 524                 */
 525                commit->indegree = 0;
 526                *pptr = work_item;
 527                pptr = &work_item->next;
 528        }
 529}
 530
 531/* merge-base stuff */
 532
 533/* bits #0..15 in revision.h */
 534#define PARENT1         (1u<<16)
 535#define PARENT2         (1u<<17)
 536#define STALE           (1u<<18)
 537#define RESULT          (1u<<19)
 538
 539static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 540
 541static struct commit *interesting(struct commit_list *list)
 542{
 543        while (list) {
 544                struct commit *commit = list->item;
 545                list = list->next;
 546                if (commit->object.flags & STALE)
 547                        continue;
 548                return commit;
 549        }
 550        return NULL;
 551}
 552
 553static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 554{
 555        struct commit_list *list = NULL;
 556        struct commit_list *result = NULL;
 557        int i;
 558
 559        for (i = 0; i < n; i++) {
 560                if (one == twos[i])
 561                        /*
 562                         * We do not mark this even with RESULT so we do not
 563                         * have to clean it up.
 564                         */
 565                        return commit_list_insert(one, &result);
 566        }
 567
 568        if (parse_commit(one))
 569                return NULL;
 570        for (i = 0; i < n; i++) {
 571                if (parse_commit(twos[i]))
 572                        return NULL;
 573        }
 574
 575        one->object.flags |= PARENT1;
 576        insert_by_date(one, &list);
 577        for (i = 0; i < n; i++) {
 578                twos[i]->object.flags |= PARENT2;
 579                insert_by_date(twos[i], &list);
 580        }
 581
 582        while (interesting(list)) {
 583                struct commit *commit;
 584                struct commit_list *parents;
 585                struct commit_list *next;
 586                int flags;
 587
 588                commit = list->item;
 589                next = list->next;
 590                free(list);
 591                list = next;
 592
 593                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 594                if (flags == (PARENT1 | PARENT2)) {
 595                        if (!(commit->object.flags & RESULT)) {
 596                                commit->object.flags |= RESULT;
 597                                insert_by_date(commit, &result);
 598                        }
 599                        /* Mark parents of a found merge stale */
 600                        flags |= STALE;
 601                }
 602                parents = commit->parents;
 603                while (parents) {
 604                        struct commit *p = parents->item;
 605                        parents = parents->next;
 606                        if ((p->object.flags & flags) == flags)
 607                                continue;
 608                        if (parse_commit(p))
 609                                return NULL;
 610                        p->object.flags |= flags;
 611                        insert_by_date(p, &list);
 612                }
 613        }
 614
 615        /* Clean up the result to remove stale ones */
 616        free_commit_list(list);
 617        list = result; result = NULL;
 618        while (list) {
 619                struct commit_list *next = list->next;
 620                if (!(list->item->object.flags & STALE))
 621                        insert_by_date(list->item, &result);
 622                free(list);
 623                list = next;
 624        }
 625        return result;
 626}
 627
 628struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 629{
 630        struct commit_list *i, *j, *k, *ret = NULL;
 631        struct commit_list **pptr = &ret;
 632
 633        for (i = in; i; i = i->next) {
 634                if (!ret)
 635                        pptr = &commit_list_insert(i->item, pptr)->next;
 636                else {
 637                        struct commit_list *new = NULL, *end = NULL;
 638
 639                        for (j = ret; j; j = j->next) {
 640                                struct commit_list *bases;
 641                                bases = get_merge_bases(i->item, j->item, 1);
 642                                if (!new)
 643                                        new = bases;
 644                                else
 645                                        end->next = bases;
 646                                for (k = bases; k; k = k->next)
 647                                        end = k;
 648                        }
 649                        ret = new;
 650                }
 651        }
 652        return ret;
 653}
 654
 655struct commit_list *get_merge_bases_many(struct commit *one,
 656                                         int n,
 657                                         struct commit **twos,
 658                                         int cleanup)
 659{
 660        struct commit_list *list;
 661        struct commit **rslt;
 662        struct commit_list *result;
 663        int cnt, i, j;
 664
 665        result = merge_bases_many(one, n, twos);
 666        for (i = 0; i < n; i++) {
 667                if (one == twos[i])
 668                        return result;
 669        }
 670        if (!result || !result->next) {
 671                if (cleanup) {
 672                        clear_commit_marks(one, all_flags);
 673                        for (i = 0; i < n; i++)
 674                                clear_commit_marks(twos[i], all_flags);
 675                }
 676                return result;
 677        }
 678
 679        /* There are more than one */
 680        cnt = 0;
 681        list = result;
 682        while (list) {
 683                list = list->next;
 684                cnt++;
 685        }
 686        rslt = xcalloc(cnt, sizeof(*rslt));
 687        for (list = result, i = 0; list; list = list->next)
 688                rslt[i++] = list->item;
 689        free_commit_list(result);
 690
 691        clear_commit_marks(one, all_flags);
 692        for (i = 0; i < n; i++)
 693                clear_commit_marks(twos[i], all_flags);
 694        for (i = 0; i < cnt - 1; i++) {
 695                for (j = i+1; j < cnt; j++) {
 696                        if (!rslt[i] || !rslt[j])
 697                                continue;
 698                        result = merge_bases_many(rslt[i], 1, &rslt[j]);
 699                        clear_commit_marks(rslt[i], all_flags);
 700                        clear_commit_marks(rslt[j], all_flags);
 701                        for (list = result; list; list = list->next) {
 702                                if (rslt[i] == list->item)
 703                                        rslt[i] = NULL;
 704                                if (rslt[j] == list->item)
 705                                        rslt[j] = NULL;
 706                        }
 707                }
 708        }
 709
 710        /* Surviving ones in rslt[] are the independent results */
 711        result = NULL;
 712        for (i = 0; i < cnt; i++) {
 713                if (rslt[i])
 714                        insert_by_date(rslt[i], &result);
 715        }
 716        free(rslt);
 717        return result;
 718}
 719
 720struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 721                                    int cleanup)
 722{
 723        return get_merge_bases_many(one, 1, &two, cleanup);
 724}
 725
 726int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 727{
 728        if (!with_commit)
 729                return 1;
 730        while (with_commit) {
 731                struct commit *other;
 732
 733                other = with_commit->item;
 734                with_commit = with_commit->next;
 735                if (in_merge_bases(other, &commit, 1))
 736                        return 1;
 737        }
 738        return 0;
 739}
 740
 741int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 742{
 743        struct commit_list *bases, *b;
 744        int ret = 0;
 745
 746        if (num == 1)
 747                bases = get_merge_bases(commit, *reference, 1);
 748        else
 749                die("not yet");
 750        for (b = bases; b; b = b->next) {
 751                if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 752                        ret = 1;
 753                        break;
 754                }
 755        }
 756
 757        free_commit_list(bases);
 758        return ret;
 759}
 760
 761struct commit_list *reduce_heads(struct commit_list *heads)
 762{
 763        struct commit_list *p;
 764        struct commit_list *result = NULL, **tail = &result;
 765        struct commit **other;
 766        size_t num_head, num_other;
 767
 768        if (!heads)
 769                return NULL;
 770
 771        /* Avoid unnecessary reallocations */
 772        for (p = heads, num_head = 0; p; p = p->next)
 773                num_head++;
 774        other = xcalloc(sizeof(*other), num_head);
 775
 776        /* For each commit, see if it can be reached by others */
 777        for (p = heads; p; p = p->next) {
 778                struct commit_list *q, *base;
 779
 780                /* Do we already have this in the result? */
 781                for (q = result; q; q = q->next)
 782                        if (p->item == q->item)
 783                                break;
 784                if (q)
 785                        continue;
 786
 787                num_other = 0;
 788                for (q = heads; q; q = q->next) {
 789                        if (p->item == q->item)
 790                                continue;
 791                        other[num_other++] = q->item;
 792                }
 793                if (num_other)
 794                        base = get_merge_bases_many(p->item, num_other, other, 1);
 795                else
 796                        base = NULL;
 797                /*
 798                 * If p->item does not have anything common with other
 799                 * commits, there won't be any merge base.  If it is
 800                 * reachable from some of the others, p->item will be
 801                 * the merge base.  If its history is connected with
 802                 * others, but p->item is not reachable by others, we
 803                 * will get something other than p->item back.
 804                 */
 805                if (!base || (base->item != p->item))
 806                        tail = &(commit_list_insert(p->item, tail)->next);
 807                free_commit_list(base);
 808        }
 809        free(other);
 810        return result;
 811}
 812
 813static const char commit_utf8_warn[] =
 814"Warning: commit message does not conform to UTF-8.\n"
 815"You may want to amend it after fixing the message, or set the config\n"
 816"variable i18n.commitencoding to the encoding your project uses.\n";
 817
 818int commit_tree(const char *msg, unsigned char *tree,
 819                struct commit_list *parents, unsigned char *ret,
 820                const char *author)
 821{
 822        int result;
 823        int encoding_is_utf8;
 824        struct strbuf buffer;
 825
 826        assert_sha1_type(tree, OBJ_TREE);
 827
 828        /* Not having i18n.commitencoding is the same as having utf-8 */
 829        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
 830
 831        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
 832        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
 833
 834        /*
 835         * NOTE! This ordering means that the same exact tree merged with a
 836         * different order of parents will be a _different_ changeset even
 837         * if everything else stays the same.
 838         */
 839        while (parents) {
 840                struct commit_list *next = parents->next;
 841                strbuf_addf(&buffer, "parent %s\n",
 842                        sha1_to_hex(parents->item->object.sha1));
 843                free(parents);
 844                parents = next;
 845        }
 846
 847        /* Person/date information */
 848        if (!author)
 849                author = git_author_info(IDENT_ERROR_ON_NO_NAME);
 850        strbuf_addf(&buffer, "author %s\n", author);
 851        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
 852        if (!encoding_is_utf8)
 853                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
 854        strbuf_addch(&buffer, '\n');
 855
 856        /* And add the comment */
 857        strbuf_addstr(&buffer, msg);
 858
 859        /* And check the encoding */
 860        if (encoding_is_utf8 && !is_utf8(buffer.buf))
 861                fprintf(stderr, commit_utf8_warn);
 862
 863        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
 864        strbuf_release(&buffer);
 865        return result;
 866}