Andrew's git / gitweb.git / commit.c
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commit.con commit Merge branch 'nl/rebase-i-cheat-sheet' (0e9b0ac)
   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#include "gpg-interface.h"
  10
  11int save_commit_buffer = 1;
  12
  13const char *commit_type = "commit";
  14
  15static struct commit *check_commit(struct object *obj,
  16                                   const unsigned char *sha1,
  17                                   int quiet)
  18{
  19        if (obj->type != OBJ_COMMIT) {
  20                if (!quiet)
  21                        error("Object %s is a %s, not a commit",
  22                              sha1_to_hex(sha1), typename(obj->type));
  23                return NULL;
  24        }
  25        return (struct commit *) obj;
  26}
  27
  28struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  29                                              int quiet)
  30{
  31        struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  32
  33        if (!obj)
  34                return NULL;
  35        return check_commit(obj, sha1, quiet);
  36}
  37
  38struct commit *lookup_commit_reference(const unsigned char *sha1)
  39{
  40        return lookup_commit_reference_gently(sha1, 0);
  41}
  42
  43struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  44{
  45        struct commit *c = lookup_commit_reference(sha1);
  46        if (!c)
  47                die(_("could not parse %s"), ref_name);
  48        if (hashcmp(sha1, c->object.sha1)) {
  49                warning(_("%s %s is not a commit!"),
  50                        ref_name, sha1_to_hex(sha1));
  51        }
  52        return c;
  53}
  54
  55struct commit *lookup_commit(const unsigned char *sha1)
  56{
  57        struct object *obj = lookup_object(sha1);
  58        if (!obj)
  59                return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  60        if (!obj->type)
  61                obj->type = OBJ_COMMIT;
  62        return check_commit(obj, sha1, 0);
  63}
  64
  65struct commit *lookup_commit_reference_by_name(const char *name)
  66{
  67        unsigned char sha1[20];
  68        struct commit *commit;
  69
  70        if (get_sha1(name, sha1))
  71                return NULL;
  72        commit = lookup_commit_reference(sha1);
  73        if (!commit || parse_commit(commit))
  74                return NULL;
  75        return commit;
  76}
  77
  78static unsigned long parse_commit_date(const char *buf, const char *tail)
  79{
  80        const char *dateptr;
  81
  82        if (buf + 6 >= tail)
  83                return 0;
  84        if (memcmp(buf, "author", 6))
  85                return 0;
  86        while (buf < tail && *buf++ != '\n')
  87                /* nada */;
  88        if (buf + 9 >= tail)
  89                return 0;
  90        if (memcmp(buf, "committer", 9))
  91                return 0;
  92        while (buf < tail && *buf++ != '>')
  93                /* nada */;
  94        if (buf >= tail)
  95                return 0;
  96        dateptr = buf;
  97        while (buf < tail && *buf++ != '\n')
  98                /* nada */;
  99        if (buf >= tail)
 100                return 0;
 101        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 102        return strtoul(dateptr, NULL, 10);
 103}
 104
 105static struct commit_graft **commit_graft;
 106static int commit_graft_alloc, commit_graft_nr;
 107
 108static int commit_graft_pos(const unsigned char *sha1)
 109{
 110        int lo, hi;
 111        lo = 0;
 112        hi = commit_graft_nr;
 113        while (lo < hi) {
 114                int mi = (lo + hi) / 2;
 115                struct commit_graft *graft = commit_graft[mi];
 116                int cmp = hashcmp(sha1, graft->sha1);
 117                if (!cmp)
 118                        return mi;
 119                if (cmp < 0)
 120                        hi = mi;
 121                else
 122                        lo = mi + 1;
 123        }
 124        return -lo - 1;
 125}
 126
 127int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 128{
 129        int pos = commit_graft_pos(graft->sha1);
 130
 131        if (0 <= pos) {
 132                if (ignore_dups)
 133                        free(graft);
 134                else {
 135                        free(commit_graft[pos]);
 136                        commit_graft[pos] = graft;
 137                }
 138                return 1;
 139        }
 140        pos = -pos - 1;
 141        if (commit_graft_alloc <= ++commit_graft_nr) {
 142                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 143                commit_graft = xrealloc(commit_graft,
 144                                        sizeof(*commit_graft) *
 145                                        commit_graft_alloc);
 146        }
 147        if (pos < commit_graft_nr)
 148                memmove(commit_graft + pos + 1,
 149                        commit_graft + pos,
 150                        (commit_graft_nr - pos - 1) *
 151                        sizeof(*commit_graft));
 152        commit_graft[pos] = graft;
 153        return 0;
 154}
 155
 156struct commit_graft *read_graft_line(char *buf, int len)
 157{
 158        /* The format is just "Commit Parent1 Parent2 ...\n" */
 159        int i;
 160        struct commit_graft *graft = NULL;
 161
 162        while (len && isspace(buf[len-1]))
 163                buf[--len] = '\0';
 164        if (buf[0] == '#' || buf[0] == '\0')
 165                return NULL;
 166        if ((len + 1) % 41)
 167                goto bad_graft_data;
 168        i = (len + 1) / 41 - 1;
 169        graft = xmalloc(sizeof(*graft) + 20 * i);
 170        graft->nr_parent = i;
 171        if (get_sha1_hex(buf, graft->sha1))
 172                goto bad_graft_data;
 173        for (i = 40; i < len; i += 41) {
 174                if (buf[i] != ' ')
 175                        goto bad_graft_data;
 176                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 177                        goto bad_graft_data;
 178        }
 179        return graft;
 180
 181bad_graft_data:
 182        error("bad graft data: %s", buf);
 183        free(graft);
 184        return NULL;
 185}
 186
 187static int read_graft_file(const char *graft_file)
 188{
 189        FILE *fp = fopen(graft_file, "r");
 190        char buf[1024];
 191        if (!fp)
 192                return -1;
 193        while (fgets(buf, sizeof(buf), fp)) {
 194                /* The format is just "Commit Parent1 Parent2 ...\n" */
 195                int len = strlen(buf);
 196                struct commit_graft *graft = read_graft_line(buf, len);
 197                if (!graft)
 198                        continue;
 199                if (register_commit_graft(graft, 1))
 200                        error("duplicate graft data: %s", buf);
 201        }
 202        fclose(fp);
 203        return 0;
 204}
 205
 206static void prepare_commit_graft(void)
 207{
 208        static int commit_graft_prepared;
 209        char *graft_file;
 210
 211        if (commit_graft_prepared)
 212                return;
 213        graft_file = get_graft_file();
 214        read_graft_file(graft_file);
 215        /* make sure shallows are read */
 216        is_repository_shallow();
 217        commit_graft_prepared = 1;
 218}
 219
 220struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 221{
 222        int pos;
 223        prepare_commit_graft();
 224        pos = commit_graft_pos(sha1);
 225        if (pos < 0)
 226                return NULL;
 227        return commit_graft[pos];
 228}
 229
 230int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 231{
 232        int i, ret;
 233        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 234                ret = fn(commit_graft[i], cb_data);
 235        return ret;
 236}
 237
 238int unregister_shallow(const unsigned char *sha1)
 239{
 240        int pos = commit_graft_pos(sha1);
 241        if (pos < 0)
 242                return -1;
 243        if (pos + 1 < commit_graft_nr)
 244                memmove(commit_graft + pos, commit_graft + pos + 1,
 245                                sizeof(struct commit_graft *)
 246                                * (commit_graft_nr - pos - 1));
 247        commit_graft_nr--;
 248        return 0;
 249}
 250
 251int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 252{
 253        const char *tail = buffer;
 254        const char *bufptr = buffer;
 255        unsigned char parent[20];
 256        struct commit_list **pptr;
 257        struct commit_graft *graft;
 258
 259        if (item->object.parsed)
 260                return 0;
 261        item->object.parsed = 1;
 262        tail += size;
 263        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 264                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 265        if (get_sha1_hex(bufptr + 5, parent) < 0)
 266                return error("bad tree pointer in commit %s",
 267                             sha1_to_hex(item->object.sha1));
 268        item->tree = lookup_tree(parent);
 269        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 270        pptr = &item->parents;
 271
 272        graft = lookup_commit_graft(item->object.sha1);
 273        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 274                struct commit *new_parent;
 275
 276                if (tail <= bufptr + 48 ||
 277                    get_sha1_hex(bufptr + 7, parent) ||
 278                    bufptr[47] != '\n')
 279                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 280                bufptr += 48;
 281                /*
 282                 * The clone is shallow if nr_parent < 0, and we must
 283                 * not traverse its real parents even when we unhide them.
 284                 */
 285                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 286                        continue;
 287                new_parent = lookup_commit(parent);
 288                if (new_parent)
 289                        pptr = &commit_list_insert(new_parent, pptr)->next;
 290        }
 291        if (graft) {
 292                int i;
 293                struct commit *new_parent;
 294                for (i = 0; i < graft->nr_parent; i++) {
 295                        new_parent = lookup_commit(graft->parent[i]);
 296                        if (!new_parent)
 297                                continue;
 298                        pptr = &commit_list_insert(new_parent, pptr)->next;
 299                }
 300        }
 301        item->date = parse_commit_date(bufptr, tail);
 302
 303        return 0;
 304}
 305
 306int parse_commit(struct commit *item)
 307{
 308        enum object_type type;
 309        void *buffer;
 310        unsigned long size;
 311        int ret;
 312
 313        if (!item)
 314                return -1;
 315        if (item->object.parsed)
 316                return 0;
 317        buffer = read_sha1_file(item->object.sha1, &type, &size);
 318        if (!buffer)
 319                return error("Could not read %s",
 320                             sha1_to_hex(item->object.sha1));
 321        if (type != OBJ_COMMIT) {
 322                free(buffer);
 323                return error("Object %s not a commit",
 324                             sha1_to_hex(item->object.sha1));
 325        }
 326        ret = parse_commit_buffer(item, buffer, size);
 327        if (save_commit_buffer && !ret) {
 328                item->buffer = buffer;
 329                return 0;
 330        }
 331        free(buffer);
 332        return ret;
 333}
 334
 335int find_commit_subject(const char *commit_buffer, const char **subject)
 336{
 337        const char *eol;
 338        const char *p = commit_buffer;
 339
 340        while (*p && (*p != '\n' || p[1] != '\n'))
 341                p++;
 342        if (*p) {
 343                p += 2;
 344                for (eol = p; *eol && *eol != '\n'; eol++)
 345                        ; /* do nothing */
 346        } else
 347                eol = p;
 348
 349        *subject = p;
 350
 351        return eol - p;
 352}
 353
 354struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 355{
 356        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 357        new_list->item = item;
 358        new_list->next = *list_p;
 359        *list_p = new_list;
 360        return new_list;
 361}
 362
 363unsigned commit_list_count(const struct commit_list *l)
 364{
 365        unsigned c = 0;
 366        for (; l; l = l->next )
 367                c++;
 368        return c;
 369}
 370
 371void free_commit_list(struct commit_list *list)
 372{
 373        while (list) {
 374                struct commit_list *temp = list;
 375                list = temp->next;
 376                free(temp);
 377        }
 378}
 379
 380struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 381{
 382        struct commit_list **pp = list;
 383        struct commit_list *p;
 384        while ((p = *pp) != NULL) {
 385                if (p->item->date < item->date) {
 386                        break;
 387                }
 388                pp = &p->next;
 389        }
 390        return commit_list_insert(item, pp);
 391}
 392
 393
 394void commit_list_sort_by_date(struct commit_list **list)
 395{
 396        struct commit_list *ret = NULL;
 397        while (*list) {
 398                commit_list_insert_by_date((*list)->item, &ret);
 399                *list = (*list)->next;
 400        }
 401        *list = ret;
 402}
 403
 404struct commit *pop_most_recent_commit(struct commit_list **list,
 405                                      unsigned int mark)
 406{
 407        struct commit *ret = (*list)->item;
 408        struct commit_list *parents = ret->parents;
 409        struct commit_list *old = *list;
 410
 411        *list = (*list)->next;
 412        free(old);
 413
 414        while (parents) {
 415                struct commit *commit = parents->item;
 416                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 417                        commit->object.flags |= mark;
 418                        commit_list_insert_by_date(commit, list);
 419                }
 420                parents = parents->next;
 421        }
 422        return ret;
 423}
 424
 425static void clear_commit_marks_1(struct commit_list **plist,
 426                                 struct commit *commit, unsigned int mark)
 427{
 428        while (commit) {
 429                struct commit_list *parents;
 430
 431                if (!(mark & commit->object.flags))
 432                        return;
 433
 434                commit->object.flags &= ~mark;
 435
 436                parents = commit->parents;
 437                if (!parents)
 438                        return;
 439
 440                while ((parents = parents->next))
 441                        commit_list_insert(parents->item, plist);
 442
 443                commit = commit->parents->item;
 444        }
 445}
 446
 447void clear_commit_marks(struct commit *commit, unsigned int mark)
 448{
 449        struct commit_list *list = NULL;
 450        commit_list_insert(commit, &list);
 451        while (list)
 452                clear_commit_marks_1(&list, pop_commit(&list), mark);
 453}
 454
 455void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 456{
 457        struct object *object;
 458        struct commit *commit;
 459        unsigned int i;
 460
 461        for (i = 0; i < a->nr; i++) {
 462                object = a->objects[i].item;
 463                commit = lookup_commit_reference_gently(object->sha1, 1);
 464                if (commit)
 465                        clear_commit_marks(commit, mark);
 466        }
 467}
 468
 469struct commit *pop_commit(struct commit_list **stack)
 470{
 471        struct commit_list *top = *stack;
 472        struct commit *item = top ? top->item : NULL;
 473
 474        if (top) {
 475                *stack = top->next;
 476                free(top);
 477        }
 478        return item;
 479}
 480
 481/*
 482 * Performs an in-place topological sort on the list supplied.
 483 */
 484void sort_in_topological_order(struct commit_list ** list, int lifo)
 485{
 486        struct commit_list *next, *orig = *list;
 487        struct commit_list *work, **insert;
 488        struct commit_list **pptr;
 489
 490        if (!orig)
 491                return;
 492        *list = NULL;
 493
 494        /* Mark them and clear the indegree */
 495        for (next = orig; next; next = next->next) {
 496                struct commit *commit = next->item;
 497                commit->indegree = 1;
 498        }
 499
 500        /* update the indegree */
 501        for (next = orig; next; next = next->next) {
 502                struct commit_list * parents = next->item->parents;
 503                while (parents) {
 504                        struct commit *parent = parents->item;
 505
 506                        if (parent->indegree)
 507                                parent->indegree++;
 508                        parents = parents->next;
 509                }
 510        }
 511
 512        /*
 513         * find the tips
 514         *
 515         * tips are nodes not reachable from any other node in the list
 516         *
 517         * the tips serve as a starting set for the work queue.
 518         */
 519        work = NULL;
 520        insert = &work;
 521        for (next = orig; next; next = next->next) {
 522                struct commit *commit = next->item;
 523
 524                if (commit->indegree == 1)
 525                        insert = &commit_list_insert(commit, insert)->next;
 526        }
 527
 528        /* process the list in topological order */
 529        if (!lifo)
 530                commit_list_sort_by_date(&work);
 531
 532        pptr = list;
 533        *list = NULL;
 534        while (work) {
 535                struct commit *commit;
 536                struct commit_list *parents, *work_item;
 537
 538                work_item = work;
 539                work = work_item->next;
 540                work_item->next = NULL;
 541
 542                commit = work_item->item;
 543                for (parents = commit->parents; parents ; parents = parents->next) {
 544                        struct commit *parent = parents->item;
 545
 546                        if (!parent->indegree)
 547                                continue;
 548
 549                        /*
 550                         * parents are only enqueued for emission
 551                         * when all their children have been emitted thereby
 552                         * guaranteeing topological order.
 553                         */
 554                        if (--parent->indegree == 1) {
 555                                if (!lifo)
 556                                        commit_list_insert_by_date(parent, &work);
 557                                else
 558                                        commit_list_insert(parent, &work);
 559                        }
 560                }
 561                /*
 562                 * work_item is a commit all of whose children
 563                 * have already been emitted. we can emit it now.
 564                 */
 565                commit->indegree = 0;
 566                *pptr = work_item;
 567                pptr = &work_item->next;
 568        }
 569}
 570
 571/* merge-base stuff */
 572
 573/* bits #0..15 in revision.h */
 574#define PARENT1         (1u<<16)
 575#define PARENT2         (1u<<17)
 576#define STALE           (1u<<18)
 577#define RESULT          (1u<<19)
 578
 579static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 580
 581static struct commit *interesting(struct commit_list *list)
 582{
 583        while (list) {
 584                struct commit *commit = list->item;
 585                list = list->next;
 586                if (commit->object.flags & STALE)
 587                        continue;
 588                return commit;
 589        }
 590        return NULL;
 591}
 592
 593static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 594{
 595        struct commit_list *list = NULL;
 596        struct commit_list *result = NULL;
 597        int i;
 598
 599        for (i = 0; i < n; i++) {
 600                if (one == twos[i])
 601                        /*
 602                         * We do not mark this even with RESULT so we do not
 603                         * have to clean it up.
 604                         */
 605                        return commit_list_insert(one, &result);
 606        }
 607
 608        if (parse_commit(one))
 609                return NULL;
 610        for (i = 0; i < n; i++) {
 611                if (parse_commit(twos[i]))
 612                        return NULL;
 613        }
 614
 615        one->object.flags |= PARENT1;
 616        commit_list_insert_by_date(one, &list);
 617        for (i = 0; i < n; i++) {
 618                twos[i]->object.flags |= PARENT2;
 619                commit_list_insert_by_date(twos[i], &list);
 620        }
 621
 622        while (interesting(list)) {
 623                struct commit *commit;
 624                struct commit_list *parents;
 625                struct commit_list *next;
 626                int flags;
 627
 628                commit = list->item;
 629                next = list->next;
 630                free(list);
 631                list = next;
 632
 633                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 634                if (flags == (PARENT1 | PARENT2)) {
 635                        if (!(commit->object.flags & RESULT)) {
 636                                commit->object.flags |= RESULT;
 637                                commit_list_insert_by_date(commit, &result);
 638                        }
 639                        /* Mark parents of a found merge stale */
 640                        flags |= STALE;
 641                }
 642                parents = commit->parents;
 643                while (parents) {
 644                        struct commit *p = parents->item;
 645                        parents = parents->next;
 646                        if ((p->object.flags & flags) == flags)
 647                                continue;
 648                        if (parse_commit(p))
 649                                return NULL;
 650                        p->object.flags |= flags;
 651                        commit_list_insert_by_date(p, &list);
 652                }
 653        }
 654
 655        /* Clean up the result to remove stale ones */
 656        free_commit_list(list);
 657        list = result; result = NULL;
 658        while (list) {
 659                struct commit_list *next = list->next;
 660                if (!(list->item->object.flags & STALE))
 661                        commit_list_insert_by_date(list->item, &result);
 662                free(list);
 663                list = next;
 664        }
 665        return result;
 666}
 667
 668struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 669{
 670        struct commit_list *i, *j, *k, *ret = NULL;
 671        struct commit_list **pptr = &ret;
 672
 673        for (i = in; i; i = i->next) {
 674                if (!ret)
 675                        pptr = &commit_list_insert(i->item, pptr)->next;
 676                else {
 677                        struct commit_list *new = NULL, *end = NULL;
 678
 679                        for (j = ret; j; j = j->next) {
 680                                struct commit_list *bases;
 681                                bases = get_merge_bases(i->item, j->item, 1);
 682                                if (!new)
 683                                        new = bases;
 684                                else
 685                                        end->next = bases;
 686                                for (k = bases; k; k = k->next)
 687                                        end = k;
 688                        }
 689                        ret = new;
 690                }
 691        }
 692        return ret;
 693}
 694
 695struct commit_list *get_merge_bases_many(struct commit *one,
 696                                         int n,
 697                                         struct commit **twos,
 698                                         int cleanup)
 699{
 700        struct commit_list *list;
 701        struct commit **rslt;
 702        struct commit_list *result;
 703        int cnt, i, j;
 704
 705        result = merge_bases_many(one, n, twos);
 706        for (i = 0; i < n; i++) {
 707                if (one == twos[i])
 708                        return result;
 709        }
 710        if (!result || !result->next) {
 711                if (cleanup) {
 712                        clear_commit_marks(one, all_flags);
 713                        for (i = 0; i < n; i++)
 714                                clear_commit_marks(twos[i], all_flags);
 715                }
 716                return result;
 717        }
 718
 719        /* There are more than one */
 720        cnt = 0;
 721        list = result;
 722        while (list) {
 723                list = list->next;
 724                cnt++;
 725        }
 726        rslt = xcalloc(cnt, sizeof(*rslt));
 727        for (list = result, i = 0; list; list = list->next)
 728                rslt[i++] = list->item;
 729        free_commit_list(result);
 730
 731        clear_commit_marks(one, all_flags);
 732        for (i = 0; i < n; i++)
 733                clear_commit_marks(twos[i], all_flags);
 734        for (i = 0; i < cnt - 1; i++) {
 735                for (j = i+1; j < cnt; j++) {
 736                        if (!rslt[i] || !rslt[j])
 737                                continue;
 738                        result = merge_bases_many(rslt[i], 1, &rslt[j]);
 739                        clear_commit_marks(rslt[i], all_flags);
 740                        clear_commit_marks(rslt[j], all_flags);
 741                        for (list = result; list; list = list->next) {
 742                                if (rslt[i] == list->item)
 743                                        rslt[i] = NULL;
 744                                if (rslt[j] == list->item)
 745                                        rslt[j] = NULL;
 746                        }
 747                }
 748        }
 749
 750        /* Surviving ones in rslt[] are the independent results */
 751        result = NULL;
 752        for (i = 0; i < cnt; i++) {
 753                if (rslt[i])
 754                        commit_list_insert_by_date(rslt[i], &result);
 755        }
 756        free(rslt);
 757        return result;
 758}
 759
 760struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 761                                    int cleanup)
 762{
 763        return get_merge_bases_many(one, 1, &two, cleanup);
 764}
 765
 766int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 767{
 768        if (!with_commit)
 769                return 1;
 770        while (with_commit) {
 771                struct commit *other;
 772
 773                other = with_commit->item;
 774                with_commit = with_commit->next;
 775                if (in_merge_bases(other, &commit, 1))
 776                        return 1;
 777        }
 778        return 0;
 779}
 780
 781int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 782{
 783        struct commit_list *bases, *b;
 784        int ret = 0;
 785
 786        if (num == 1)
 787                bases = get_merge_bases(commit, *reference, 1);
 788        else
 789                die("not yet");
 790        for (b = bases; b; b = b->next) {
 791                if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 792                        ret = 1;
 793                        break;
 794                }
 795        }
 796
 797        free_commit_list(bases);
 798        return ret;
 799}
 800
 801struct commit_list *reduce_heads(struct commit_list *heads)
 802{
 803        struct commit_list *p;
 804        struct commit_list *result = NULL, **tail = &result;
 805        struct commit **other;
 806        size_t num_head, num_other;
 807
 808        if (!heads)
 809                return NULL;
 810
 811        /* Avoid unnecessary reallocations */
 812        for (p = heads, num_head = 0; p; p = p->next)
 813                num_head++;
 814        other = xcalloc(sizeof(*other), num_head);
 815
 816        /* For each commit, see if it can be reached by others */
 817        for (p = heads; p; p = p->next) {
 818                struct commit_list *q, *base;
 819
 820                /* Do we already have this in the result? */
 821                for (q = result; q; q = q->next)
 822                        if (p->item == q->item)
 823                                break;
 824                if (q)
 825                        continue;
 826
 827                num_other = 0;
 828                for (q = heads; q; q = q->next) {
 829                        if (p->item == q->item)
 830                                continue;
 831                        other[num_other++] = q->item;
 832                }
 833                if (num_other)
 834                        base = get_merge_bases_many(p->item, num_other, other, 1);
 835                else
 836                        base = NULL;
 837                /*
 838                 * If p->item does not have anything common with other
 839                 * commits, there won't be any merge base.  If it is
 840                 * reachable from some of the others, p->item will be
 841                 * the merge base.  If its history is connected with
 842                 * others, but p->item is not reachable by others, we
 843                 * will get something other than p->item back.
 844                 */
 845                if (!base || (base->item != p->item))
 846                        tail = &(commit_list_insert(p->item, tail)->next);
 847                free_commit_list(base);
 848        }
 849        free(other);
 850        return result;
 851}
 852
 853static const char gpg_sig_header[] = "gpgsig";
 854static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 855
 856static int do_sign_commit(struct strbuf *buf, const char *keyid)
 857{
 858        struct strbuf sig = STRBUF_INIT;
 859        int inspos, copypos;
 860
 861        /* find the end of the header */
 862        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
 863
 864        if (!keyid || !*keyid)
 865                keyid = get_signing_key();
 866        if (sign_buffer(buf, &sig, keyid)) {
 867                strbuf_release(&sig);
 868                return -1;
 869        }
 870
 871        for (copypos = 0; sig.buf[copypos]; ) {
 872                const char *bol = sig.buf + copypos;
 873                const char *eol = strchrnul(bol, '\n');
 874                int len = (eol - bol) + !!*eol;
 875
 876                if (!copypos) {
 877                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
 878                        inspos += gpg_sig_header_len;
 879                }
 880                strbuf_insert(buf, inspos++, " ", 1);
 881                strbuf_insert(buf, inspos, bol, len);
 882                inspos += len;
 883                copypos += len;
 884        }
 885        strbuf_release(&sig);
 886        return 0;
 887}
 888
 889int parse_signed_commit(const unsigned char *sha1,
 890                        struct strbuf *payload, struct strbuf *signature)
 891{
 892        unsigned long size;
 893        enum object_type type;
 894        char *buffer = read_sha1_file(sha1, &type, &size);
 895        int in_signature, saw_signature = -1;
 896        char *line, *tail;
 897
 898        if (!buffer || type != OBJ_COMMIT)
 899                goto cleanup;
 900
 901        line = buffer;
 902        tail = buffer + size;
 903        in_signature = 0;
 904        saw_signature = 0;
 905        while (line < tail) {
 906                const char *sig = NULL;
 907                char *next = memchr(line, '\n', tail - line);
 908
 909                next = next ? next + 1 : tail;
 910                if (in_signature && line[0] == ' ')
 911                        sig = line + 1;
 912                else if (!prefixcmp(line, gpg_sig_header) &&
 913                         line[gpg_sig_header_len] == ' ')
 914                        sig = line + gpg_sig_header_len + 1;
 915                if (sig) {
 916                        strbuf_add(signature, sig, next - sig);
 917                        saw_signature = 1;
 918                        in_signature = 1;
 919                } else {
 920                        if (*line == '\n')
 921                                /* dump the whole remainder of the buffer */
 922                                next = tail;
 923                        strbuf_add(payload, line, next - line);
 924                        in_signature = 0;
 925                }
 926                line = next;
 927        }
 928 cleanup:
 929        free(buffer);
 930        return saw_signature;
 931}
 932
 933static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 934{
 935        struct merge_remote_desc *desc;
 936        struct commit_extra_header *mergetag;
 937        char *buf;
 938        unsigned long size, len;
 939        enum object_type type;
 940
 941        desc = merge_remote_util(parent);
 942        if (!desc || !desc->obj)
 943                return;
 944        buf = read_sha1_file(desc->obj->sha1, &type, &size);
 945        if (!buf || type != OBJ_TAG)
 946                goto free_return;
 947        len = parse_signature(buf, size);
 948        if (size == len)
 949                goto free_return;
 950        /*
 951         * We could verify this signature and either omit the tag when
 952         * it does not validate, but the integrator may not have the
 953         * public key of the signer of the tag he is merging, while a
 954         * later auditor may have it while auditing, so let's not run
 955         * verify-signed-buffer here for now...
 956         *
 957         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 958         *      warn("warning: signed tag unverified.");
 959         */
 960        mergetag = xcalloc(1, sizeof(*mergetag));
 961        mergetag->key = xstrdup("mergetag");
 962        mergetag->value = buf;
 963        mergetag->len = size;
 964
 965        **tail = mergetag;
 966        *tail = &mergetag->next;
 967        return;
 968
 969free_return:
 970        free(buf);
 971}
 972
 973void append_merge_tag_headers(struct commit_list *parents,
 974                              struct commit_extra_header ***tail)
 975{
 976        while (parents) {
 977                struct commit *parent = parents->item;
 978                handle_signed_tag(parent, tail);
 979                parents = parents->next;
 980        }
 981}
 982
 983static void add_extra_header(struct strbuf *buffer,
 984                             struct commit_extra_header *extra)
 985{
 986        strbuf_addstr(buffer, extra->key);
 987        if (extra->len)
 988                strbuf_add_lines(buffer, " ", extra->value, extra->len);
 989        else
 990                strbuf_addch(buffer, '\n');
 991}
 992
 993struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
 994                                                      const char **exclude)
 995{
 996        struct commit_extra_header *extra = NULL;
 997        unsigned long size;
 998        enum object_type type;
 999        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1000        if (buffer && type == OBJ_COMMIT)
1001                extra = read_commit_extra_header_lines(buffer, size, exclude);
1002        free(buffer);
1003        return extra;
1004}
1005
1006static inline int standard_header_field(const char *field, size_t len)
1007{
1008        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1009                (len == 6 && !memcmp(field, "parent ", 7)) ||
1010                (len == 6 && !memcmp(field, "author ", 7)) ||
1011                (len == 9 && !memcmp(field, "committer ", 10)) ||
1012                (len == 8 && !memcmp(field, "encoding ", 9)));
1013}
1014
1015static int excluded_header_field(const char *field, size_t len, const char **exclude)
1016{
1017        if (!exclude)
1018                return 0;
1019
1020        while (*exclude) {
1021                size_t xlen = strlen(*exclude);
1022                if (len == xlen &&
1023                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1024                        return 1;
1025                exclude++;
1026        }
1027        return 0;
1028}
1029
1030struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size,
1031                                                           const char **exclude)
1032{
1033        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1034        const char *line, *next, *eof, *eob;
1035        struct strbuf buf = STRBUF_INIT;
1036
1037        for (line = buffer, eob = line + size;
1038             line < eob && *line != '\n';
1039             line = next) {
1040                next = memchr(line, '\n', eob - line);
1041                next = next ? next + 1 : eob;
1042                if (*line == ' ') {
1043                        /* continuation */
1044                        if (it)
1045                                strbuf_add(&buf, line + 1, next - (line + 1));
1046                        continue;
1047                }
1048                if (it)
1049                        it->value = strbuf_detach(&buf, &it->len);
1050                strbuf_reset(&buf);
1051                it = NULL;
1052
1053                eof = strchr(line, ' ');
1054                if (next <= eof)
1055                        eof = next;
1056
1057                if (standard_header_field(line, eof - line) ||
1058                    excluded_header_field(line, eof - line, exclude))
1059                        continue;
1060
1061                it = xcalloc(1, sizeof(*it));
1062                it->key = xmemdupz(line, eof-line);
1063                *tail = it;
1064                tail = &it->next;
1065                if (eof + 1 < next)
1066                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1067        }
1068        if (it)
1069                it->value = strbuf_detach(&buf, &it->len);
1070        return extra;
1071}
1072
1073void free_commit_extra_headers(struct commit_extra_header *extra)
1074{
1075        while (extra) {
1076                struct commit_extra_header *next = extra->next;
1077                free(extra->key);
1078                free(extra->value);
1079                free(extra);
1080                extra = next;
1081        }
1082}
1083
1084int commit_tree(const struct strbuf *msg, unsigned char *tree,
1085                struct commit_list *parents, unsigned char *ret,
1086                const char *author, const char *sign_commit)
1087{
1088        struct commit_extra_header *extra = NULL, **tail = &extra;
1089        int result;
1090
1091        append_merge_tag_headers(parents, &tail);
1092        result = commit_tree_extended(msg, tree, parents, ret,
1093                                      author, sign_commit, extra);
1094        free_commit_extra_headers(extra);
1095        return result;
1096}
1097
1098static const char commit_utf8_warn[] =
1099"Warning: commit message does not conform to UTF-8.\n"
1100"You may want to amend it after fixing the message, or set the config\n"
1101"variable i18n.commitencoding to the encoding your project uses.\n";
1102
1103int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1104                         struct commit_list *parents, unsigned char *ret,
1105                         const char *author, const char *sign_commit,
1106                         struct commit_extra_header *extra)
1107{
1108        int result;
1109        int encoding_is_utf8;
1110        struct strbuf buffer;
1111
1112        assert_sha1_type(tree, OBJ_TREE);
1113
1114        if (memchr(msg->buf, '\0', msg->len))
1115                return error("a NUL byte in commit log message not allowed.");
1116
1117        /* Not having i18n.commitencoding is the same as having utf-8 */
1118        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1119
1120        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1121        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1122
1123        /*
1124         * NOTE! This ordering means that the same exact tree merged with a
1125         * different order of parents will be a _different_ changeset even
1126         * if everything else stays the same.
1127         */
1128        while (parents) {
1129                struct commit_list *next = parents->next;
1130                struct commit *parent = parents->item;
1131
1132                strbuf_addf(&buffer, "parent %s\n",
1133                            sha1_to_hex(parent->object.sha1));
1134                free(parents);
1135                parents = next;
1136        }
1137
1138        /* Person/date information */
1139        if (!author)
1140                author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1141        strbuf_addf(&buffer, "author %s\n", author);
1142        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1143        if (!encoding_is_utf8)
1144                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1145
1146        while (extra) {
1147                add_extra_header(&buffer, extra);
1148                extra = extra->next;
1149        }
1150        strbuf_addch(&buffer, '\n');
1151
1152        /* And add the comment */
1153        strbuf_addbuf(&buffer, msg);
1154
1155        /* And check the encoding */
1156        if (encoding_is_utf8 && !is_utf8(buffer.buf))
1157                fprintf(stderr, commit_utf8_warn);
1158
1159        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1160                return -1;
1161
1162        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1163        strbuf_release(&buffer);
1164        return result;
1165}
1166
1167struct commit *get_merge_parent(const char *name)
1168{
1169        struct object *obj;
1170        struct commit *commit;
1171        unsigned char sha1[20];
1172        if (get_sha1(name, sha1))
1173                return NULL;
1174        obj = parse_object(sha1);
1175        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1176        if (commit && !commit->util) {
1177                struct merge_remote_desc *desc;
1178                desc = xmalloc(sizeof(*desc));
1179                desc->obj = obj;
1180                desc->name = strdup(name);
1181                commit->util = desc;
1182        }
1183        return commit;
1184}