Andrew's git / gitweb.git / commit.c
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commit.con commit parse_object: try internal cache before reading object db (ccdc603)
   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_or_die(const unsigned char *sha1, const char *ref_name)
  43{
  44        struct commit *c = lookup_commit_reference(sha1);
  45        if (!c)
  46                die(_("could not parse %s"), ref_name);
  47        if (hashcmp(sha1, c->object.sha1)) {
  48                warning(_("%s %s is not a commit!"),
  49                        ref_name, sha1_to_hex(sha1));
  50        }
  51        return c;
  52}
  53
  54struct commit *lookup_commit(const unsigned char *sha1)
  55{
  56        struct object *obj = lookup_object(sha1);
  57        if (!obj)
  58                return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  59        if (!obj->type)
  60                obj->type = OBJ_COMMIT;
  61        return check_commit(obj, sha1, 0);
  62}
  63
  64struct commit *lookup_commit_reference_by_name(const char *name)
  65{
  66        unsigned char sha1[20];
  67        struct commit *commit;
  68
  69        if (get_sha1(name, sha1))
  70                return NULL;
  71        commit = lookup_commit_reference(sha1);
  72        if (!commit || parse_commit(commit))
  73                return NULL;
  74        return commit;
  75}
  76
  77static unsigned long parse_commit_date(const char *buf, const char *tail)
  78{
  79        const char *dateptr;
  80
  81        if (buf + 6 >= tail)
  82                return 0;
  83        if (memcmp(buf, "author", 6))
  84                return 0;
  85        while (buf < tail && *buf++ != '\n')
  86                /* nada */;
  87        if (buf + 9 >= tail)
  88                return 0;
  89        if (memcmp(buf, "committer", 9))
  90                return 0;
  91        while (buf < tail && *buf++ != '>')
  92                /* nada */;
  93        if (buf >= tail)
  94                return 0;
  95        dateptr = buf;
  96        while (buf < tail && *buf++ != '\n')
  97                /* nada */;
  98        if (buf >= tail)
  99                return 0;
 100        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 101        return strtoul(dateptr, NULL, 10);
 102}
 103
 104static struct commit_graft **commit_graft;
 105static int commit_graft_alloc, commit_graft_nr;
 106
 107static int commit_graft_pos(const unsigned char *sha1)
 108{
 109        int lo, hi;
 110        lo = 0;
 111        hi = commit_graft_nr;
 112        while (lo < hi) {
 113                int mi = (lo + hi) / 2;
 114                struct commit_graft *graft = commit_graft[mi];
 115                int cmp = hashcmp(sha1, graft->sha1);
 116                if (!cmp)
 117                        return mi;
 118                if (cmp < 0)
 119                        hi = mi;
 120                else
 121                        lo = mi + 1;
 122        }
 123        return -lo - 1;
 124}
 125
 126int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 127{
 128        int pos = commit_graft_pos(graft->sha1);
 129
 130        if (0 <= pos) {
 131                if (ignore_dups)
 132                        free(graft);
 133                else {
 134                        free(commit_graft[pos]);
 135                        commit_graft[pos] = graft;
 136                }
 137                return 1;
 138        }
 139        pos = -pos - 1;
 140        if (commit_graft_alloc <= ++commit_graft_nr) {
 141                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 142                commit_graft = xrealloc(commit_graft,
 143                                        sizeof(*commit_graft) *
 144                                        commit_graft_alloc);
 145        }
 146        if (pos < commit_graft_nr)
 147                memmove(commit_graft + pos + 1,
 148                        commit_graft + pos,
 149                        (commit_graft_nr - pos - 1) *
 150                        sizeof(*commit_graft));
 151        commit_graft[pos] = graft;
 152        return 0;
 153}
 154
 155struct commit_graft *read_graft_line(char *buf, int len)
 156{
 157        /* The format is just "Commit Parent1 Parent2 ...\n" */
 158        int i;
 159        struct commit_graft *graft = NULL;
 160
 161        while (len && isspace(buf[len-1]))
 162                buf[--len] = '\0';
 163        if (buf[0] == '#' || buf[0] == '\0')
 164                return NULL;
 165        if ((len + 1) % 41)
 166                goto bad_graft_data;
 167        i = (len + 1) / 41 - 1;
 168        graft = xmalloc(sizeof(*graft) + 20 * i);
 169        graft->nr_parent = i;
 170        if (get_sha1_hex(buf, graft->sha1))
 171                goto bad_graft_data;
 172        for (i = 40; i < len; i += 41) {
 173                if (buf[i] != ' ')
 174                        goto bad_graft_data;
 175                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 176                        goto bad_graft_data;
 177        }
 178        return graft;
 179
 180bad_graft_data:
 181        error("bad graft data: %s", buf);
 182        free(graft);
 183        return NULL;
 184}
 185
 186static int read_graft_file(const char *graft_file)
 187{
 188        FILE *fp = fopen(graft_file, "r");
 189        char buf[1024];
 190        if (!fp)
 191                return -1;
 192        while (fgets(buf, sizeof(buf), fp)) {
 193                /* The format is just "Commit Parent1 Parent2 ...\n" */
 194                int len = strlen(buf);
 195                struct commit_graft *graft = read_graft_line(buf, len);
 196                if (!graft)
 197                        continue;
 198                if (register_commit_graft(graft, 1))
 199                        error("duplicate graft data: %s", buf);
 200        }
 201        fclose(fp);
 202        return 0;
 203}
 204
 205static void prepare_commit_graft(void)
 206{
 207        static int commit_graft_prepared;
 208        char *graft_file;
 209
 210        if (commit_graft_prepared)
 211                return;
 212        graft_file = get_graft_file();
 213        read_graft_file(graft_file);
 214        /* make sure shallows are read */
 215        is_repository_shallow();
 216        commit_graft_prepared = 1;
 217}
 218
 219struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 220{
 221        int pos;
 222        prepare_commit_graft();
 223        pos = commit_graft_pos(sha1);
 224        if (pos < 0)
 225                return NULL;
 226        return commit_graft[pos];
 227}
 228
 229int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 230{
 231        int i, ret;
 232        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 233                ret = fn(commit_graft[i], cb_data);
 234        return ret;
 235}
 236
 237int unregister_shallow(const unsigned char *sha1)
 238{
 239        int pos = commit_graft_pos(sha1);
 240        if (pos < 0)
 241                return -1;
 242        if (pos + 1 < commit_graft_nr)
 243                memmove(commit_graft + pos, commit_graft + pos + 1,
 244                                sizeof(struct commit_graft *)
 245                                * (commit_graft_nr - pos - 1));
 246        commit_graft_nr--;
 247        return 0;
 248}
 249
 250int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 251{
 252        const char *tail = buffer;
 253        const char *bufptr = buffer;
 254        unsigned char parent[20];
 255        struct commit_list **pptr;
 256        struct commit_graft *graft;
 257
 258        if (item->object.parsed)
 259                return 0;
 260        item->object.parsed = 1;
 261        tail += size;
 262        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 263                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 264        if (get_sha1_hex(bufptr + 5, parent) < 0)
 265                return error("bad tree pointer in commit %s",
 266                             sha1_to_hex(item->object.sha1));
 267        item->tree = lookup_tree(parent);
 268        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 269        pptr = &item->parents;
 270
 271        graft = lookup_commit_graft(item->object.sha1);
 272        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 273                struct commit *new_parent;
 274
 275                if (tail <= bufptr + 48 ||
 276                    get_sha1_hex(bufptr + 7, parent) ||
 277                    bufptr[47] != '\n')
 278                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 279                bufptr += 48;
 280                /*
 281                 * The clone is shallow if nr_parent < 0, and we must
 282                 * not traverse its real parents even when we unhide them.
 283                 */
 284                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 285                        continue;
 286                new_parent = lookup_commit(parent);
 287                if (new_parent)
 288                        pptr = &commit_list_insert(new_parent, pptr)->next;
 289        }
 290        if (graft) {
 291                int i;
 292                struct commit *new_parent;
 293                for (i = 0; i < graft->nr_parent; i++) {
 294                        new_parent = lookup_commit(graft->parent[i]);
 295                        if (!new_parent)
 296                                continue;
 297                        pptr = &commit_list_insert(new_parent, pptr)->next;
 298                }
 299        }
 300        item->date = parse_commit_date(bufptr, tail);
 301
 302        return 0;
 303}
 304
 305int parse_commit(struct commit *item)
 306{
 307        enum object_type type;
 308        void *buffer;
 309        unsigned long size;
 310        int ret;
 311
 312        if (!item)
 313                return -1;
 314        if (item->object.parsed)
 315                return 0;
 316        buffer = read_sha1_file(item->object.sha1, &type, &size);
 317        if (!buffer)
 318                return error("Could not read %s",
 319                             sha1_to_hex(item->object.sha1));
 320        if (type != OBJ_COMMIT) {
 321                free(buffer);
 322                return error("Object %s not a commit",
 323                             sha1_to_hex(item->object.sha1));
 324        }
 325        ret = parse_commit_buffer(item, buffer, size);
 326        if (save_commit_buffer && !ret) {
 327                item->buffer = buffer;
 328                return 0;
 329        }
 330        free(buffer);
 331        return ret;
 332}
 333
 334int find_commit_subject(const char *commit_buffer, const char **subject)
 335{
 336        const char *eol;
 337        const char *p = commit_buffer;
 338
 339        while (*p && (*p != '\n' || p[1] != '\n'))
 340                p++;
 341        if (*p) {
 342                p += 2;
 343                for (eol = p; *eol && *eol != '\n'; eol++)
 344                        ; /* do nothing */
 345        } else
 346                eol = p;
 347
 348        *subject = p;
 349
 350        return eol - p;
 351}
 352
 353struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 354{
 355        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 356        new_list->item = item;
 357        new_list->next = *list_p;
 358        *list_p = new_list;
 359        return new_list;
 360}
 361
 362unsigned commit_list_count(const struct commit_list *l)
 363{
 364        unsigned c = 0;
 365        for (; l; l = l->next )
 366                c++;
 367        return c;
 368}
 369
 370void free_commit_list(struct commit_list *list)
 371{
 372        while (list) {
 373                struct commit_list *temp = list;
 374                list = temp->next;
 375                free(temp);
 376        }
 377}
 378
 379struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 380{
 381        struct commit_list **pp = list;
 382        struct commit_list *p;
 383        while ((p = *pp) != NULL) {
 384                if (p->item->date < item->date) {
 385                        break;
 386                }
 387                pp = &p->next;
 388        }
 389        return commit_list_insert(item, pp);
 390}
 391
 392
 393void commit_list_sort_by_date(struct commit_list **list)
 394{
 395        struct commit_list *ret = NULL;
 396        while (*list) {
 397                commit_list_insert_by_date((*list)->item, &ret);
 398                *list = (*list)->next;
 399        }
 400        *list = ret;
 401}
 402
 403struct commit *pop_most_recent_commit(struct commit_list **list,
 404                                      unsigned int mark)
 405{
 406        struct commit *ret = (*list)->item;
 407        struct commit_list *parents = ret->parents;
 408        struct commit_list *old = *list;
 409
 410        *list = (*list)->next;
 411        free(old);
 412
 413        while (parents) {
 414                struct commit *commit = parents->item;
 415                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 416                        commit->object.flags |= mark;
 417                        commit_list_insert_by_date(commit, list);
 418                }
 419                parents = parents->next;
 420        }
 421        return ret;
 422}
 423
 424void clear_commit_marks(struct commit *commit, unsigned int mark)
 425{
 426        while (commit) {
 427                struct commit_list *parents;
 428
 429                if (!(mark & commit->object.flags))
 430                        return;
 431
 432                commit->object.flags &= ~mark;
 433
 434                parents = commit->parents;
 435                if (!parents)
 436                        return;
 437
 438                while ((parents = parents->next))
 439                        clear_commit_marks(parents->item, mark);
 440
 441                commit = commit->parents->item;
 442        }
 443}
 444
 445void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 446{
 447        struct object *object;
 448        struct commit *commit;
 449        unsigned int i;
 450
 451        for (i = 0; i < a->nr; i++) {
 452                object = a->objects[i].item;
 453                commit = lookup_commit_reference_gently(object->sha1, 1);
 454                if (commit)
 455                        clear_commit_marks(commit, mark);
 456        }
 457}
 458
 459struct commit *pop_commit(struct commit_list **stack)
 460{
 461        struct commit_list *top = *stack;
 462        struct commit *item = top ? top->item : NULL;
 463
 464        if (top) {
 465                *stack = top->next;
 466                free(top);
 467        }
 468        return item;
 469}
 470
 471/*
 472 * Performs an in-place topological sort on the list supplied.
 473 */
 474void sort_in_topological_order(struct commit_list ** list, int lifo)
 475{
 476        struct commit_list *next, *orig = *list;
 477        struct commit_list *work, **insert;
 478        struct commit_list **pptr;
 479
 480        if (!orig)
 481                return;
 482        *list = NULL;
 483
 484        /* Mark them and clear the indegree */
 485        for (next = orig; next; next = next->next) {
 486                struct commit *commit = next->item;
 487                commit->indegree = 1;
 488        }
 489
 490        /* update the indegree */
 491        for (next = orig; next; next = next->next) {
 492                struct commit_list * parents = next->item->parents;
 493                while (parents) {
 494                        struct commit *parent = parents->item;
 495
 496                        if (parent->indegree)
 497                                parent->indegree++;
 498                        parents = parents->next;
 499                }
 500        }
 501
 502        /*
 503         * find the tips
 504         *
 505         * tips are nodes not reachable from any other node in the list
 506         *
 507         * the tips serve as a starting set for the work queue.
 508         */
 509        work = NULL;
 510        insert = &work;
 511        for (next = orig; next; next = next->next) {
 512                struct commit *commit = next->item;
 513
 514                if (commit->indegree == 1)
 515                        insert = &commit_list_insert(commit, insert)->next;
 516        }
 517
 518        /* process the list in topological order */
 519        if (!lifo)
 520                commit_list_sort_by_date(&work);
 521
 522        pptr = list;
 523        *list = NULL;
 524        while (work) {
 525                struct commit *commit;
 526                struct commit_list *parents, *work_item;
 527
 528                work_item = work;
 529                work = work_item->next;
 530                work_item->next = NULL;
 531
 532                commit = work_item->item;
 533                for (parents = commit->parents; parents ; parents = parents->next) {
 534                        struct commit *parent = parents->item;
 535
 536                        if (!parent->indegree)
 537                                continue;
 538
 539                        /*
 540                         * parents are only enqueued for emission
 541                         * when all their children have been emitted thereby
 542                         * guaranteeing topological order.
 543                         */
 544                        if (--parent->indegree == 1) {
 545                                if (!lifo)
 546                                        commit_list_insert_by_date(parent, &work);
 547                                else
 548                                        commit_list_insert(parent, &work);
 549                        }
 550                }
 551                /*
 552                 * work_item is a commit all of whose children
 553                 * have already been emitted. we can emit it now.
 554                 */
 555                commit->indegree = 0;
 556                *pptr = work_item;
 557                pptr = &work_item->next;
 558        }
 559}
 560
 561/* merge-base stuff */
 562
 563/* bits #0..15 in revision.h */
 564#define PARENT1         (1u<<16)
 565#define PARENT2         (1u<<17)
 566#define STALE           (1u<<18)
 567#define RESULT          (1u<<19)
 568
 569static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 570
 571static struct commit *interesting(struct commit_list *list)
 572{
 573        while (list) {
 574                struct commit *commit = list->item;
 575                list = list->next;
 576                if (commit->object.flags & STALE)
 577                        continue;
 578                return commit;
 579        }
 580        return NULL;
 581}
 582
 583static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 584{
 585        struct commit_list *list = NULL;
 586        struct commit_list *result = NULL;
 587        int i;
 588
 589        for (i = 0; i < n; i++) {
 590                if (one == twos[i])
 591                        /*
 592                         * We do not mark this even with RESULT so we do not
 593                         * have to clean it up.
 594                         */
 595                        return commit_list_insert(one, &result);
 596        }
 597
 598        if (parse_commit(one))
 599                return NULL;
 600        for (i = 0; i < n; i++) {
 601                if (parse_commit(twos[i]))
 602                        return NULL;
 603        }
 604
 605        one->object.flags |= PARENT1;
 606        commit_list_insert_by_date(one, &list);
 607        for (i = 0; i < n; i++) {
 608                twos[i]->object.flags |= PARENT2;
 609                commit_list_insert_by_date(twos[i], &list);
 610        }
 611
 612        while (interesting(list)) {
 613                struct commit *commit;
 614                struct commit_list *parents;
 615                struct commit_list *next;
 616                int flags;
 617
 618                commit = list->item;
 619                next = list->next;
 620                free(list);
 621                list = next;
 622
 623                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 624                if (flags == (PARENT1 | PARENT2)) {
 625                        if (!(commit->object.flags & RESULT)) {
 626                                commit->object.flags |= RESULT;
 627                                commit_list_insert_by_date(commit, &result);
 628                        }
 629                        /* Mark parents of a found merge stale */
 630                        flags |= STALE;
 631                }
 632                parents = commit->parents;
 633                while (parents) {
 634                        struct commit *p = parents->item;
 635                        parents = parents->next;
 636                        if ((p->object.flags & flags) == flags)
 637                                continue;
 638                        if (parse_commit(p))
 639                                return NULL;
 640                        p->object.flags |= flags;
 641                        commit_list_insert_by_date(p, &list);
 642                }
 643        }
 644
 645        /* Clean up the result to remove stale ones */
 646        free_commit_list(list);
 647        list = result; result = NULL;
 648        while (list) {
 649                struct commit_list *next = list->next;
 650                if (!(list->item->object.flags & STALE))
 651                        commit_list_insert_by_date(list->item, &result);
 652                free(list);
 653                list = next;
 654        }
 655        return result;
 656}
 657
 658struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 659{
 660        struct commit_list *i, *j, *k, *ret = NULL;
 661        struct commit_list **pptr = &ret;
 662
 663        for (i = in; i; i = i->next) {
 664                if (!ret)
 665                        pptr = &commit_list_insert(i->item, pptr)->next;
 666                else {
 667                        struct commit_list *new = NULL, *end = NULL;
 668
 669                        for (j = ret; j; j = j->next) {
 670                                struct commit_list *bases;
 671                                bases = get_merge_bases(i->item, j->item, 1);
 672                                if (!new)
 673                                        new = bases;
 674                                else
 675                                        end->next = bases;
 676                                for (k = bases; k; k = k->next)
 677                                        end = k;
 678                        }
 679                        ret = new;
 680                }
 681        }
 682        return ret;
 683}
 684
 685struct commit_list *get_merge_bases_many(struct commit *one,
 686                                         int n,
 687                                         struct commit **twos,
 688                                         int cleanup)
 689{
 690        struct commit_list *list;
 691        struct commit **rslt;
 692        struct commit_list *result;
 693        int cnt, i, j;
 694
 695        result = merge_bases_many(one, n, twos);
 696        for (i = 0; i < n; i++) {
 697                if (one == twos[i])
 698                        return result;
 699        }
 700        if (!result || !result->next) {
 701                if (cleanup) {
 702                        clear_commit_marks(one, all_flags);
 703                        for (i = 0; i < n; i++)
 704                                clear_commit_marks(twos[i], all_flags);
 705                }
 706                return result;
 707        }
 708
 709        /* There are more than one */
 710        cnt = 0;
 711        list = result;
 712        while (list) {
 713                list = list->next;
 714                cnt++;
 715        }
 716        rslt = xcalloc(cnt, sizeof(*rslt));
 717        for (list = result, i = 0; list; list = list->next)
 718                rslt[i++] = list->item;
 719        free_commit_list(result);
 720
 721        clear_commit_marks(one, all_flags);
 722        for (i = 0; i < n; i++)
 723                clear_commit_marks(twos[i], all_flags);
 724        for (i = 0; i < cnt - 1; i++) {
 725                for (j = i+1; j < cnt; j++) {
 726                        if (!rslt[i] || !rslt[j])
 727                                continue;
 728                        result = merge_bases_many(rslt[i], 1, &rslt[j]);
 729                        clear_commit_marks(rslt[i], all_flags);
 730                        clear_commit_marks(rslt[j], all_flags);
 731                        for (list = result; list; list = list->next) {
 732                                if (rslt[i] == list->item)
 733                                        rslt[i] = NULL;
 734                                if (rslt[j] == list->item)
 735                                        rslt[j] = NULL;
 736                        }
 737                }
 738        }
 739
 740        /* Surviving ones in rslt[] are the independent results */
 741        result = NULL;
 742        for (i = 0; i < cnt; i++) {
 743                if (rslt[i])
 744                        commit_list_insert_by_date(rslt[i], &result);
 745        }
 746        free(rslt);
 747        return result;
 748}
 749
 750struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 751                                    int cleanup)
 752{
 753        return get_merge_bases_many(one, 1, &two, cleanup);
 754}
 755
 756int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 757{
 758        if (!with_commit)
 759                return 1;
 760        while (with_commit) {
 761                struct commit *other;
 762
 763                other = with_commit->item;
 764                with_commit = with_commit->next;
 765                if (in_merge_bases(other, &commit, 1))
 766                        return 1;
 767        }
 768        return 0;
 769}
 770
 771int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 772{
 773        struct commit_list *bases, *b;
 774        int ret = 0;
 775
 776        if (num == 1)
 777                bases = get_merge_bases(commit, *reference, 1);
 778        else
 779                die("not yet");
 780        for (b = bases; b; b = b->next) {
 781                if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 782                        ret = 1;
 783                        break;
 784                }
 785        }
 786
 787        free_commit_list(bases);
 788        return ret;
 789}
 790
 791struct commit_list *reduce_heads(struct commit_list *heads)
 792{
 793        struct commit_list *p;
 794        struct commit_list *result = NULL, **tail = &result;
 795        struct commit **other;
 796        size_t num_head, num_other;
 797
 798        if (!heads)
 799                return NULL;
 800
 801        /* Avoid unnecessary reallocations */
 802        for (p = heads, num_head = 0; p; p = p->next)
 803                num_head++;
 804        other = xcalloc(sizeof(*other), num_head);
 805
 806        /* For each commit, see if it can be reached by others */
 807        for (p = heads; p; p = p->next) {
 808                struct commit_list *q, *base;
 809
 810                /* Do we already have this in the result? */
 811                for (q = result; q; q = q->next)
 812                        if (p->item == q->item)
 813                                break;
 814                if (q)
 815                        continue;
 816
 817                num_other = 0;
 818                for (q = heads; q; q = q->next) {
 819                        if (p->item == q->item)
 820                                continue;
 821                        other[num_other++] = q->item;
 822                }
 823                if (num_other)
 824                        base = get_merge_bases_many(p->item, num_other, other, 1);
 825                else
 826                        base = NULL;
 827                /*
 828                 * If p->item does not have anything common with other
 829                 * commits, there won't be any merge base.  If it is
 830                 * reachable from some of the others, p->item will be
 831                 * the merge base.  If its history is connected with
 832                 * others, but p->item is not reachable by others, we
 833                 * will get something other than p->item back.
 834                 */
 835                if (!base || (base->item != p->item))
 836                        tail = &(commit_list_insert(p->item, tail)->next);
 837                free_commit_list(base);
 838        }
 839        free(other);
 840        return result;
 841}
 842
 843static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 844{
 845        struct merge_remote_desc *desc;
 846        struct commit_extra_header *mergetag;
 847        char *buf;
 848        unsigned long size, len;
 849        enum object_type type;
 850
 851        desc = merge_remote_util(parent);
 852        if (!desc || !desc->obj)
 853                return;
 854        buf = read_sha1_file(desc->obj->sha1, &type, &size);
 855        if (!buf || type != OBJ_TAG)
 856                goto free_return;
 857        len = parse_signature(buf, size);
 858        if (size == len)
 859                goto free_return;
 860        /*
 861         * We could verify this signature and either omit the tag when
 862         * it does not validate, but the integrator may not have the
 863         * public key of the signer of the tag he is merging, while a
 864         * later auditor may have it while auditing, so let's not run
 865         * verify-signed-buffer here for now...
 866         *
 867         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 868         *      warn("warning: signed tag unverified.");
 869         */
 870        mergetag = xcalloc(1, sizeof(*mergetag));
 871        mergetag->key = xstrdup("mergetag");
 872        mergetag->value = buf;
 873        mergetag->len = size;
 874
 875        **tail = mergetag;
 876        *tail = &mergetag->next;
 877        return;
 878
 879free_return:
 880        free(buf);
 881}
 882
 883void append_merge_tag_headers(struct commit_list *parents,
 884                              struct commit_extra_header ***tail)
 885{
 886        while (parents) {
 887                struct commit *parent = parents->item;
 888                handle_signed_tag(parent, tail);
 889                parents = parents->next;
 890        }
 891}
 892
 893static void add_extra_header(struct strbuf *buffer,
 894                             struct commit_extra_header *extra)
 895{
 896        strbuf_addstr(buffer, extra->key);
 897        if (extra->len)
 898                strbuf_add_lines(buffer, " ", extra->value, extra->len);
 899        else
 900                strbuf_addch(buffer, '\n');
 901}
 902
 903struct commit_extra_header *read_commit_extra_headers(struct commit *commit)
 904{
 905        struct commit_extra_header *extra = NULL;
 906        unsigned long size;
 907        enum object_type type;
 908        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
 909        if (buffer && type == OBJ_COMMIT)
 910                extra = read_commit_extra_header_lines(buffer, size);
 911        free(buffer);
 912        return extra;
 913}
 914
 915static inline int standard_header_field(const char *field, size_t len)
 916{
 917        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
 918                (len == 6 && !memcmp(field, "parent ", 7)) ||
 919                (len == 6 && !memcmp(field, "author ", 7)) ||
 920                (len == 9 && !memcmp(field, "committer ", 10)) ||
 921                (len == 8 && !memcmp(field, "encoding ", 9)));
 922}
 923
 924struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size)
 925{
 926        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
 927        const char *line, *next, *eof, *eob;
 928        struct strbuf buf = STRBUF_INIT;
 929
 930        for (line = buffer, eob = line + size;
 931             line < eob && *line != '\n';
 932             line = next) {
 933                next = memchr(line, '\n', eob - line);
 934                next = next ? next + 1 : eob;
 935                if (*line == ' ') {
 936                        /* continuation */
 937                        if (it)
 938                                strbuf_add(&buf, line + 1, next - (line + 1));
 939                        continue;
 940                }
 941                if (it)
 942                        it->value = strbuf_detach(&buf, &it->len);
 943                strbuf_reset(&buf);
 944                it = NULL;
 945
 946                eof = strchr(line, ' ');
 947                if (next <= eof)
 948                        eof = next;
 949
 950                if (standard_header_field(line, eof - line))
 951                        continue;
 952
 953                it = xcalloc(1, sizeof(*it));
 954                it->key = xmemdupz(line, eof-line);
 955                *tail = it;
 956                tail = &it->next;
 957                if (eof + 1 < next)
 958                        strbuf_add(&buf, eof + 1, next - (eof + 1));
 959        }
 960        if (it)
 961                it->value = strbuf_detach(&buf, &it->len);
 962        return extra;
 963}
 964
 965void free_commit_extra_headers(struct commit_extra_header *extra)
 966{
 967        while (extra) {
 968                struct commit_extra_header *next = extra->next;
 969                free(extra->key);
 970                free(extra->value);
 971                free(extra);
 972                extra = next;
 973        }
 974}
 975
 976int commit_tree(const struct strbuf *msg, unsigned char *tree,
 977                struct commit_list *parents, unsigned char *ret,
 978                const char *author)
 979{
 980        struct commit_extra_header *extra = NULL, **tail = &extra;
 981        int result;
 982
 983        append_merge_tag_headers(parents, &tail);
 984        result = commit_tree_extended(msg, tree, parents, ret, author, extra);
 985        free_commit_extra_headers(extra);
 986        return result;
 987}
 988
 989static const char commit_utf8_warn[] =
 990"Warning: commit message does not conform to UTF-8.\n"
 991"You may want to amend it after fixing the message, or set the config\n"
 992"variable i18n.commitencoding to the encoding your project uses.\n";
 993
 994int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
 995                         struct commit_list *parents, unsigned char *ret,
 996                         const char *author, struct commit_extra_header *extra)
 997{
 998        int result;
 999        int encoding_is_utf8;
1000        struct strbuf buffer;
1001
1002        assert_sha1_type(tree, OBJ_TREE);
1003
1004        if (memchr(msg->buf, '\0', msg->len))
1005                return error("a NUL byte in commit log message not allowed.");
1006
1007        /* Not having i18n.commitencoding is the same as having utf-8 */
1008        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1009
1010        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1011        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1012
1013        /*
1014         * NOTE! This ordering means that the same exact tree merged with a
1015         * different order of parents will be a _different_ changeset even
1016         * if everything else stays the same.
1017         */
1018        while (parents) {
1019                struct commit_list *next = parents->next;
1020                struct commit *parent = parents->item;
1021
1022                strbuf_addf(&buffer, "parent %s\n",
1023                            sha1_to_hex(parent->object.sha1));
1024                free(parents);
1025                parents = next;
1026        }
1027
1028        /* Person/date information */
1029        if (!author)
1030                author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1031        strbuf_addf(&buffer, "author %s\n", author);
1032        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1033        if (!encoding_is_utf8)
1034                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1035
1036        while (extra) {
1037                add_extra_header(&buffer, extra);
1038                extra = extra->next;
1039        }
1040        strbuf_addch(&buffer, '\n');
1041
1042        /* And add the comment */
1043        strbuf_addbuf(&buffer, msg);
1044
1045        /* And check the encoding */
1046        if (encoding_is_utf8 && !is_utf8(buffer.buf))
1047                fprintf(stderr, commit_utf8_warn);
1048
1049        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1050        strbuf_release(&buffer);
1051        return result;
1052}
1053
1054struct commit *get_merge_parent(const char *name)
1055{
1056        struct object *obj;
1057        struct commit *commit;
1058        unsigned char sha1[20];
1059        if (get_sha1(name, sha1))
1060                return NULL;
1061        obj = parse_object(sha1);
1062        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1063        if (commit && !commit->util) {
1064                struct merge_remote_desc *desc;
1065                desc = xmalloc(sizeof(*desc));
1066                desc->obj = obj;
1067                desc->name = strdup(name);
1068                commit->util = desc;
1069        }
1070        return commit;
1071}