Andrew's git / gitweb.git / commit.c
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commit.con commit Merge branch 'jc/maint-pull-docfix' (6d73dba)
   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#include "mergesort.h"
  11#include "commit-slab.h"
  12#include "prio-queue.h"
  13
  14static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  15
  16int save_commit_buffer = 1;
  17
  18const char *commit_type = "commit";
  19static int commit_count;
  20
  21static struct commit *check_commit(struct object *obj,
  22                                   const unsigned char *sha1,
  23                                   int quiet)
  24{
  25        if (obj->type != OBJ_COMMIT) {
  26                if (!quiet)
  27                        error("Object %s is a %s, not a commit",
  28                              sha1_to_hex(sha1), typename(obj->type));
  29                return NULL;
  30        }
  31        return (struct commit *) obj;
  32}
  33
  34struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  35                                              int quiet)
  36{
  37        struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  38
  39        if (!obj)
  40                return NULL;
  41        return check_commit(obj, sha1, quiet);
  42}
  43
  44struct commit *lookup_commit_reference(const unsigned char *sha1)
  45{
  46        return lookup_commit_reference_gently(sha1, 0);
  47}
  48
  49struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  50{
  51        struct commit *c = lookup_commit_reference(sha1);
  52        if (!c)
  53                die(_("could not parse %s"), ref_name);
  54        if (hashcmp(sha1, c->object.sha1)) {
  55                warning(_("%s %s is not a commit!"),
  56                        ref_name, sha1_to_hex(sha1));
  57        }
  58        return c;
  59}
  60
  61struct commit *lookup_commit(const unsigned char *sha1)
  62{
  63        struct object *obj = lookup_object(sha1);
  64        if (!obj) {
  65                struct commit *c = alloc_commit_node();
  66                c->index = commit_count++;
  67                return create_object(sha1, OBJ_COMMIT, c);
  68        }
  69        if (!obj->type)
  70                obj->type = OBJ_COMMIT;
  71        return check_commit(obj, sha1, 0);
  72}
  73
  74struct commit *lookup_commit_reference_by_name(const char *name)
  75{
  76        unsigned char sha1[20];
  77        struct commit *commit;
  78
  79        if (get_sha1_committish(name, sha1))
  80                return NULL;
  81        commit = lookup_commit_reference(sha1);
  82        if (parse_commit(commit))
  83                return NULL;
  84        return commit;
  85}
  86
  87static unsigned long parse_commit_date(const char *buf, const char *tail)
  88{
  89        const char *dateptr;
  90
  91        if (buf + 6 >= tail)
  92                return 0;
  93        if (memcmp(buf, "author", 6))
  94                return 0;
  95        while (buf < tail && *buf++ != '\n')
  96                /* nada */;
  97        if (buf + 9 >= tail)
  98                return 0;
  99        if (memcmp(buf, "committer", 9))
 100                return 0;
 101        while (buf < tail && *buf++ != '>')
 102                /* nada */;
 103        if (buf >= tail)
 104                return 0;
 105        dateptr = buf;
 106        while (buf < tail && *buf++ != '\n')
 107                /* nada */;
 108        if (buf >= tail)
 109                return 0;
 110        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 111        return strtoul(dateptr, NULL, 10);
 112}
 113
 114static struct commit_graft **commit_graft;
 115static int commit_graft_alloc, commit_graft_nr;
 116
 117static int commit_graft_pos(const unsigned char *sha1)
 118{
 119        int lo, hi;
 120        lo = 0;
 121        hi = commit_graft_nr;
 122        while (lo < hi) {
 123                int mi = (lo + hi) / 2;
 124                struct commit_graft *graft = commit_graft[mi];
 125                int cmp = hashcmp(sha1, graft->sha1);
 126                if (!cmp)
 127                        return mi;
 128                if (cmp < 0)
 129                        hi = mi;
 130                else
 131                        lo = mi + 1;
 132        }
 133        return -lo - 1;
 134}
 135
 136int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 137{
 138        int pos = commit_graft_pos(graft->sha1);
 139
 140        if (0 <= pos) {
 141                if (ignore_dups)
 142                        free(graft);
 143                else {
 144                        free(commit_graft[pos]);
 145                        commit_graft[pos] = graft;
 146                }
 147                return 1;
 148        }
 149        pos = -pos - 1;
 150        if (commit_graft_alloc <= ++commit_graft_nr) {
 151                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 152                commit_graft = xrealloc(commit_graft,
 153                                        sizeof(*commit_graft) *
 154                                        commit_graft_alloc);
 155        }
 156        if (pos < commit_graft_nr)
 157                memmove(commit_graft + pos + 1,
 158                        commit_graft + pos,
 159                        (commit_graft_nr - pos - 1) *
 160                        sizeof(*commit_graft));
 161        commit_graft[pos] = graft;
 162        return 0;
 163}
 164
 165struct commit_graft *read_graft_line(char *buf, int len)
 166{
 167        /* The format is just "Commit Parent1 Parent2 ...\n" */
 168        int i;
 169        struct commit_graft *graft = NULL;
 170
 171        while (len && isspace(buf[len-1]))
 172                buf[--len] = '\0';
 173        if (buf[0] == '#' || buf[0] == '\0')
 174                return NULL;
 175        if ((len + 1) % 41)
 176                goto bad_graft_data;
 177        i = (len + 1) / 41 - 1;
 178        graft = xmalloc(sizeof(*graft) + 20 * i);
 179        graft->nr_parent = i;
 180        if (get_sha1_hex(buf, graft->sha1))
 181                goto bad_graft_data;
 182        for (i = 40; i < len; i += 41) {
 183                if (buf[i] != ' ')
 184                        goto bad_graft_data;
 185                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 186                        goto bad_graft_data;
 187        }
 188        return graft;
 189
 190bad_graft_data:
 191        error("bad graft data: %s", buf);
 192        free(graft);
 193        return NULL;
 194}
 195
 196static int read_graft_file(const char *graft_file)
 197{
 198        FILE *fp = fopen(graft_file, "r");
 199        struct strbuf buf = STRBUF_INIT;
 200        if (!fp)
 201                return -1;
 202        while (!strbuf_getwholeline(&buf, fp, '\n')) {
 203                /* The format is just "Commit Parent1 Parent2 ...\n" */
 204                struct commit_graft *graft = read_graft_line(buf.buf, buf.len);
 205                if (!graft)
 206                        continue;
 207                if (register_commit_graft(graft, 1))
 208                        error("duplicate graft data: %s", buf.buf);
 209        }
 210        fclose(fp);
 211        strbuf_release(&buf);
 212        return 0;
 213}
 214
 215static void prepare_commit_graft(void)
 216{
 217        static int commit_graft_prepared;
 218        char *graft_file;
 219
 220        if (commit_graft_prepared)
 221                return;
 222        graft_file = get_graft_file();
 223        read_graft_file(graft_file);
 224        /* make sure shallows are read */
 225        is_repository_shallow();
 226        commit_graft_prepared = 1;
 227}
 228
 229struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 230{
 231        int pos;
 232        prepare_commit_graft();
 233        pos = commit_graft_pos(sha1);
 234        if (pos < 0)
 235                return NULL;
 236        return commit_graft[pos];
 237}
 238
 239int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 240{
 241        int i, ret;
 242        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 243                ret = fn(commit_graft[i], cb_data);
 244        return ret;
 245}
 246
 247int unregister_shallow(const unsigned char *sha1)
 248{
 249        int pos = commit_graft_pos(sha1);
 250        if (pos < 0)
 251                return -1;
 252        if (pos + 1 < commit_graft_nr)
 253                memmove(commit_graft + pos, commit_graft + pos + 1,
 254                                sizeof(struct commit_graft *)
 255                                * (commit_graft_nr - pos - 1));
 256        commit_graft_nr--;
 257        return 0;
 258}
 259
 260int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 261{
 262        const char *tail = buffer;
 263        const char *bufptr = buffer;
 264        unsigned char parent[20];
 265        struct commit_list **pptr;
 266        struct commit_graft *graft;
 267
 268        if (item->object.parsed)
 269                return 0;
 270        item->object.parsed = 1;
 271        tail += size;
 272        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 273                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 274        if (get_sha1_hex(bufptr + 5, parent) < 0)
 275                return error("bad tree pointer in commit %s",
 276                             sha1_to_hex(item->object.sha1));
 277        item->tree = lookup_tree(parent);
 278        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 279        pptr = &item->parents;
 280
 281        graft = lookup_commit_graft(item->object.sha1);
 282        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 283                struct commit *new_parent;
 284
 285                if (tail <= bufptr + 48 ||
 286                    get_sha1_hex(bufptr + 7, parent) ||
 287                    bufptr[47] != '\n')
 288                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 289                bufptr += 48;
 290                /*
 291                 * The clone is shallow if nr_parent < 0, and we must
 292                 * not traverse its real parents even when we unhide them.
 293                 */
 294                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 295                        continue;
 296                new_parent = lookup_commit(parent);
 297                if (new_parent)
 298                        pptr = &commit_list_insert(new_parent, pptr)->next;
 299        }
 300        if (graft) {
 301                int i;
 302                struct commit *new_parent;
 303                for (i = 0; i < graft->nr_parent; i++) {
 304                        new_parent = lookup_commit(graft->parent[i]);
 305                        if (!new_parent)
 306                                continue;
 307                        pptr = &commit_list_insert(new_parent, pptr)->next;
 308                }
 309        }
 310        item->date = parse_commit_date(bufptr, tail);
 311
 312        return 0;
 313}
 314
 315int parse_commit(struct commit *item)
 316{
 317        enum object_type type;
 318        void *buffer;
 319        unsigned long size;
 320        int ret;
 321
 322        if (!item)
 323                return -1;
 324        if (item->object.parsed)
 325                return 0;
 326        buffer = read_sha1_file(item->object.sha1, &type, &size);
 327        if (!buffer)
 328                return error("Could not read %s",
 329                             sha1_to_hex(item->object.sha1));
 330        if (type != OBJ_COMMIT) {
 331                free(buffer);
 332                return error("Object %s not a commit",
 333                             sha1_to_hex(item->object.sha1));
 334        }
 335        ret = parse_commit_buffer(item, buffer, size);
 336        if (save_commit_buffer && !ret) {
 337                item->buffer = buffer;
 338                return 0;
 339        }
 340        free(buffer);
 341        return ret;
 342}
 343
 344void parse_commit_or_die(struct commit *item)
 345{
 346        if (parse_commit(item))
 347                die("unable to parse commit %s",
 348                    item ? sha1_to_hex(item->object.sha1) : "(null)");
 349}
 350
 351int find_commit_subject(const char *commit_buffer, const char **subject)
 352{
 353        const char *eol;
 354        const char *p = commit_buffer;
 355
 356        while (*p && (*p != '\n' || p[1] != '\n'))
 357                p++;
 358        if (*p) {
 359                p += 2;
 360                for (eol = p; *eol && *eol != '\n'; eol++)
 361                        ; /* do nothing */
 362        } else
 363                eol = p;
 364
 365        *subject = p;
 366
 367        return eol - p;
 368}
 369
 370struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 371{
 372        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 373        new_list->item = item;
 374        new_list->next = *list_p;
 375        *list_p = new_list;
 376        return new_list;
 377}
 378
 379unsigned commit_list_count(const struct commit_list *l)
 380{
 381        unsigned c = 0;
 382        for (; l; l = l->next )
 383                c++;
 384        return c;
 385}
 386
 387struct commit_list *copy_commit_list(struct commit_list *list)
 388{
 389        struct commit_list *head = NULL;
 390        struct commit_list **pp = &head;
 391        while (list) {
 392                struct commit_list *new;
 393                new = xmalloc(sizeof(struct commit_list));
 394                new->item = list->item;
 395                new->next = NULL;
 396                *pp = new;
 397                pp = &new->next;
 398                list = list->next;
 399        }
 400        return head;
 401}
 402
 403void free_commit_list(struct commit_list *list)
 404{
 405        while (list) {
 406                struct commit_list *temp = list;
 407                list = temp->next;
 408                free(temp);
 409        }
 410}
 411
 412struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 413{
 414        struct commit_list **pp = list;
 415        struct commit_list *p;
 416        while ((p = *pp) != NULL) {
 417                if (p->item->date < item->date) {
 418                        break;
 419                }
 420                pp = &p->next;
 421        }
 422        return commit_list_insert(item, pp);
 423}
 424
 425static int commit_list_compare_by_date(const void *a, const void *b)
 426{
 427        unsigned long a_date = ((const struct commit_list *)a)->item->date;
 428        unsigned long b_date = ((const struct commit_list *)b)->item->date;
 429        if (a_date < b_date)
 430                return 1;
 431        if (a_date > b_date)
 432                return -1;
 433        return 0;
 434}
 435
 436static void *commit_list_get_next(const void *a)
 437{
 438        return ((const struct commit_list *)a)->next;
 439}
 440
 441static void commit_list_set_next(void *a, void *next)
 442{
 443        ((struct commit_list *)a)->next = next;
 444}
 445
 446void commit_list_sort_by_date(struct commit_list **list)
 447{
 448        *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 449                                commit_list_compare_by_date);
 450}
 451
 452struct commit *pop_most_recent_commit(struct commit_list **list,
 453                                      unsigned int mark)
 454{
 455        struct commit *ret = (*list)->item;
 456        struct commit_list *parents = ret->parents;
 457        struct commit_list *old = *list;
 458
 459        *list = (*list)->next;
 460        free(old);
 461
 462        while (parents) {
 463                struct commit *commit = parents->item;
 464                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 465                        commit->object.flags |= mark;
 466                        commit_list_insert_by_date(commit, list);
 467                }
 468                parents = parents->next;
 469        }
 470        return ret;
 471}
 472
 473static void clear_commit_marks_1(struct commit_list **plist,
 474                                 struct commit *commit, unsigned int mark)
 475{
 476        while (commit) {
 477                struct commit_list *parents;
 478
 479                if (!(mark & commit->object.flags))
 480                        return;
 481
 482                commit->object.flags &= ~mark;
 483
 484                parents = commit->parents;
 485                if (!parents)
 486                        return;
 487
 488                while ((parents = parents->next))
 489                        commit_list_insert(parents->item, plist);
 490
 491                commit = commit->parents->item;
 492        }
 493}
 494
 495void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 496{
 497        struct commit_list *list = NULL;
 498
 499        while (nr--) {
 500                commit_list_insert(*commit, &list);
 501                commit++;
 502        }
 503        while (list)
 504                clear_commit_marks_1(&list, pop_commit(&list), mark);
 505}
 506
 507void clear_commit_marks(struct commit *commit, unsigned int mark)
 508{
 509        clear_commit_marks_many(1, &commit, mark);
 510}
 511
 512void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 513{
 514        struct object *object;
 515        struct commit *commit;
 516        unsigned int i;
 517
 518        for (i = 0; i < a->nr; i++) {
 519                object = a->objects[i].item;
 520                commit = lookup_commit_reference_gently(object->sha1, 1);
 521                if (commit)
 522                        clear_commit_marks(commit, mark);
 523        }
 524}
 525
 526struct commit *pop_commit(struct commit_list **stack)
 527{
 528        struct commit_list *top = *stack;
 529        struct commit *item = top ? top->item : NULL;
 530
 531        if (top) {
 532                *stack = top->next;
 533                free(top);
 534        }
 535        return item;
 536}
 537
 538/*
 539 * Topological sort support
 540 */
 541
 542/* count number of children that have not been emitted */
 543define_commit_slab(indegree_slab, int);
 544
 545/* record author-date for each commit object */
 546define_commit_slab(author_date_slab, unsigned long);
 547
 548static void record_author_date(struct author_date_slab *author_date,
 549                               struct commit *commit)
 550{
 551        const char *buf, *line_end;
 552        char *buffer = NULL;
 553        struct ident_split ident;
 554        char *date_end;
 555        unsigned long date;
 556
 557        if (!commit->buffer) {
 558                unsigned long size;
 559                enum object_type type;
 560                buffer = read_sha1_file(commit->object.sha1, &type, &size);
 561                if (!buffer)
 562                        return;
 563        }
 564
 565        for (buf = commit->buffer ? commit->buffer : buffer;
 566             buf;
 567             buf = line_end + 1) {
 568                line_end = strchrnul(buf, '\n');
 569                if (!starts_with(buf, "author ")) {
 570                        if (!line_end[0] || line_end[1] == '\n')
 571                                return; /* end of header */
 572                        continue;
 573                }
 574                if (split_ident_line(&ident,
 575                                     buf + strlen("author "),
 576                                     line_end - (buf + strlen("author "))) ||
 577                    !ident.date_begin || !ident.date_end)
 578                        goto fail_exit; /* malformed "author" line */
 579                break;
 580        }
 581
 582        date = strtoul(ident.date_begin, &date_end, 10);
 583        if (date_end != ident.date_end)
 584                goto fail_exit; /* malformed date */
 585        *(author_date_slab_at(author_date, commit)) = date;
 586
 587fail_exit:
 588        free(buffer);
 589}
 590
 591static int compare_commits_by_author_date(const void *a_, const void *b_,
 592                                          void *cb_data)
 593{
 594        const struct commit *a = a_, *b = b_;
 595        struct author_date_slab *author_date = cb_data;
 596        unsigned long a_date = *(author_date_slab_at(author_date, a));
 597        unsigned long b_date = *(author_date_slab_at(author_date, b));
 598
 599        /* newer commits with larger date first */
 600        if (a_date < b_date)
 601                return 1;
 602        else if (a_date > b_date)
 603                return -1;
 604        return 0;
 605}
 606
 607int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 608{
 609        const struct commit *a = a_, *b = b_;
 610        /* newer commits with larger date first */
 611        if (a->date < b->date)
 612                return 1;
 613        else if (a->date > b->date)
 614                return -1;
 615        return 0;
 616}
 617
 618/*
 619 * Performs an in-place topological sort on the list supplied.
 620 */
 621void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 622{
 623        struct commit_list *next, *orig = *list;
 624        struct commit_list **pptr;
 625        struct indegree_slab indegree;
 626        struct prio_queue queue;
 627        struct commit *commit;
 628        struct author_date_slab author_date;
 629
 630        if (!orig)
 631                return;
 632        *list = NULL;
 633
 634        init_indegree_slab(&indegree);
 635        memset(&queue, '\0', sizeof(queue));
 636
 637        switch (sort_order) {
 638        default: /* REV_SORT_IN_GRAPH_ORDER */
 639                queue.compare = NULL;
 640                break;
 641        case REV_SORT_BY_COMMIT_DATE:
 642                queue.compare = compare_commits_by_commit_date;
 643                break;
 644        case REV_SORT_BY_AUTHOR_DATE:
 645                init_author_date_slab(&author_date);
 646                queue.compare = compare_commits_by_author_date;
 647                queue.cb_data = &author_date;
 648                break;
 649        }
 650
 651        /* Mark them and clear the indegree */
 652        for (next = orig; next; next = next->next) {
 653                struct commit *commit = next->item;
 654                *(indegree_slab_at(&indegree, commit)) = 1;
 655                /* also record the author dates, if needed */
 656                if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 657                        record_author_date(&author_date, commit);
 658        }
 659
 660        /* update the indegree */
 661        for (next = orig; next; next = next->next) {
 662                struct commit_list *parents = next->item->parents;
 663                while (parents) {
 664                        struct commit *parent = parents->item;
 665                        int *pi = indegree_slab_at(&indegree, parent);
 666
 667                        if (*pi)
 668                                (*pi)++;
 669                        parents = parents->next;
 670                }
 671        }
 672
 673        /*
 674         * find the tips
 675         *
 676         * tips are nodes not reachable from any other node in the list
 677         *
 678         * the tips serve as a starting set for the work queue.
 679         */
 680        for (next = orig; next; next = next->next) {
 681                struct commit *commit = next->item;
 682
 683                if (*(indegree_slab_at(&indegree, commit)) == 1)
 684                        prio_queue_put(&queue, commit);
 685        }
 686
 687        /*
 688         * This is unfortunate; the initial tips need to be shown
 689         * in the order given from the revision traversal machinery.
 690         */
 691        if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 692                prio_queue_reverse(&queue);
 693
 694        /* We no longer need the commit list */
 695        free_commit_list(orig);
 696
 697        pptr = list;
 698        *list = NULL;
 699        while ((commit = prio_queue_get(&queue)) != NULL) {
 700                struct commit_list *parents;
 701
 702                for (parents = commit->parents; parents ; parents = parents->next) {
 703                        struct commit *parent = parents->item;
 704                        int *pi = indegree_slab_at(&indegree, parent);
 705
 706                        if (!*pi)
 707                                continue;
 708
 709                        /*
 710                         * parents are only enqueued for emission
 711                         * when all their children have been emitted thereby
 712                         * guaranteeing topological order.
 713                         */
 714                        if (--(*pi) == 1)
 715                                prio_queue_put(&queue, parent);
 716                }
 717                /*
 718                 * all children of commit have already been
 719                 * emitted. we can emit it now.
 720                 */
 721                *(indegree_slab_at(&indegree, commit)) = 0;
 722
 723                pptr = &commit_list_insert(commit, pptr)->next;
 724        }
 725
 726        clear_indegree_slab(&indegree);
 727        clear_prio_queue(&queue);
 728        if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 729                clear_author_date_slab(&author_date);
 730}
 731
 732/* merge-base stuff */
 733
 734/* bits #0..15 in revision.h */
 735#define PARENT1         (1u<<16)
 736#define PARENT2         (1u<<17)
 737#define STALE           (1u<<18)
 738#define RESULT          (1u<<19)
 739
 740static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 741
 742static struct commit *interesting(struct commit_list *list)
 743{
 744        while (list) {
 745                struct commit *commit = list->item;
 746                list = list->next;
 747                if (commit->object.flags & STALE)
 748                        continue;
 749                return commit;
 750        }
 751        return NULL;
 752}
 753
 754/* all input commits in one and twos[] must have been parsed! */
 755static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 756{
 757        struct commit_list *list = NULL;
 758        struct commit_list *result = NULL;
 759        int i;
 760
 761        one->object.flags |= PARENT1;
 762        commit_list_insert_by_date(one, &list);
 763        if (!n)
 764                return list;
 765        for (i = 0; i < n; i++) {
 766                twos[i]->object.flags |= PARENT2;
 767                commit_list_insert_by_date(twos[i], &list);
 768        }
 769
 770        while (interesting(list)) {
 771                struct commit *commit;
 772                struct commit_list *parents;
 773                struct commit_list *next;
 774                int flags;
 775
 776                commit = list->item;
 777                next = list->next;
 778                free(list);
 779                list = next;
 780
 781                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 782                if (flags == (PARENT1 | PARENT2)) {
 783                        if (!(commit->object.flags & RESULT)) {
 784                                commit->object.flags |= RESULT;
 785                                commit_list_insert_by_date(commit, &result);
 786                        }
 787                        /* Mark parents of a found merge stale */
 788                        flags |= STALE;
 789                }
 790                parents = commit->parents;
 791                while (parents) {
 792                        struct commit *p = parents->item;
 793                        parents = parents->next;
 794                        if ((p->object.flags & flags) == flags)
 795                                continue;
 796                        if (parse_commit(p))
 797                                return NULL;
 798                        p->object.flags |= flags;
 799                        commit_list_insert_by_date(p, &list);
 800                }
 801        }
 802
 803        free_commit_list(list);
 804        return result;
 805}
 806
 807static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 808{
 809        struct commit_list *list = NULL;
 810        struct commit_list *result = NULL;
 811        int i;
 812
 813        for (i = 0; i < n; i++) {
 814                if (one == twos[i])
 815                        /*
 816                         * We do not mark this even with RESULT so we do not
 817                         * have to clean it up.
 818                         */
 819                        return commit_list_insert(one, &result);
 820        }
 821
 822        if (parse_commit(one))
 823                return NULL;
 824        for (i = 0; i < n; i++) {
 825                if (parse_commit(twos[i]))
 826                        return NULL;
 827        }
 828
 829        list = paint_down_to_common(one, n, twos);
 830
 831        while (list) {
 832                struct commit_list *next = list->next;
 833                if (!(list->item->object.flags & STALE))
 834                        commit_list_insert_by_date(list->item, &result);
 835                free(list);
 836                list = next;
 837        }
 838        return result;
 839}
 840
 841struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 842{
 843        struct commit_list *i, *j, *k, *ret = NULL;
 844
 845        if (!in)
 846                return ret;
 847
 848        commit_list_insert(in->item, &ret);
 849
 850        for (i = in->next; i; i = i->next) {
 851                struct commit_list *new = NULL, *end = NULL;
 852
 853                for (j = ret; j; j = j->next) {
 854                        struct commit_list *bases;
 855                        bases = get_merge_bases(i->item, j->item, 1);
 856                        if (!new)
 857                                new = bases;
 858                        else
 859                                end->next = bases;
 860                        for (k = bases; k; k = k->next)
 861                                end = k;
 862                }
 863                ret = new;
 864        }
 865        return ret;
 866}
 867
 868static int remove_redundant(struct commit **array, int cnt)
 869{
 870        /*
 871         * Some commit in the array may be an ancestor of
 872         * another commit.  Move such commit to the end of
 873         * the array, and return the number of commits that
 874         * are independent from each other.
 875         */
 876        struct commit **work;
 877        unsigned char *redundant;
 878        int *filled_index;
 879        int i, j, filled;
 880
 881        work = xcalloc(cnt, sizeof(*work));
 882        redundant = xcalloc(cnt, 1);
 883        filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 884
 885        for (i = 0; i < cnt; i++)
 886                parse_commit(array[i]);
 887        for (i = 0; i < cnt; i++) {
 888                struct commit_list *common;
 889
 890                if (redundant[i])
 891                        continue;
 892                for (j = filled = 0; j < cnt; j++) {
 893                        if (i == j || redundant[j])
 894                                continue;
 895                        filled_index[filled] = j;
 896                        work[filled++] = array[j];
 897                }
 898                common = paint_down_to_common(array[i], filled, work);
 899                if (array[i]->object.flags & PARENT2)
 900                        redundant[i] = 1;
 901                for (j = 0; j < filled; j++)
 902                        if (work[j]->object.flags & PARENT1)
 903                                redundant[filled_index[j]] = 1;
 904                clear_commit_marks(array[i], all_flags);
 905                for (j = 0; j < filled; j++)
 906                        clear_commit_marks(work[j], all_flags);
 907                free_commit_list(common);
 908        }
 909
 910        /* Now collect the result */
 911        memcpy(work, array, sizeof(*array) * cnt);
 912        for (i = filled = 0; i < cnt; i++)
 913                if (!redundant[i])
 914                        array[filled++] = work[i];
 915        for (j = filled, i = 0; i < cnt; i++)
 916                if (redundant[i])
 917                        array[j++] = work[i];
 918        free(work);
 919        free(redundant);
 920        free(filled_index);
 921        return filled;
 922}
 923
 924struct commit_list *get_merge_bases_many(struct commit *one,
 925                                         int n,
 926                                         struct commit **twos,
 927                                         int cleanup)
 928{
 929        struct commit_list *list;
 930        struct commit **rslt;
 931        struct commit_list *result;
 932        int cnt, i;
 933
 934        result = merge_bases_many(one, n, twos);
 935        for (i = 0; i < n; i++) {
 936                if (one == twos[i])
 937                        return result;
 938        }
 939        if (!result || !result->next) {
 940                if (cleanup) {
 941                        clear_commit_marks(one, all_flags);
 942                        clear_commit_marks_many(n, twos, all_flags);
 943                }
 944                return result;
 945        }
 946
 947        /* There are more than one */
 948        cnt = 0;
 949        list = result;
 950        while (list) {
 951                list = list->next;
 952                cnt++;
 953        }
 954        rslt = xcalloc(cnt, sizeof(*rslt));
 955        for (list = result, i = 0; list; list = list->next)
 956                rslt[i++] = list->item;
 957        free_commit_list(result);
 958
 959        clear_commit_marks(one, all_flags);
 960        clear_commit_marks_many(n, twos, all_flags);
 961
 962        cnt = remove_redundant(rslt, cnt);
 963        result = NULL;
 964        for (i = 0; i < cnt; i++)
 965                commit_list_insert_by_date(rslt[i], &result);
 966        free(rslt);
 967        return result;
 968}
 969
 970struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 971                                    int cleanup)
 972{
 973        return get_merge_bases_many(one, 1, &two, cleanup);
 974}
 975
 976/*
 977 * Is "commit" a descendant of one of the elements on the "with_commit" list?
 978 */
 979int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 980{
 981        if (!with_commit)
 982                return 1;
 983        while (with_commit) {
 984                struct commit *other;
 985
 986                other = with_commit->item;
 987                with_commit = with_commit->next;
 988                if (in_merge_bases(other, commit))
 989                        return 1;
 990        }
 991        return 0;
 992}
 993
 994/*
 995 * Is "commit" an ancestor of one of the "references"?
 996 */
 997int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 998{
 999        struct commit_list *bases;
1000        int ret = 0, i;
1001
1002        if (parse_commit(commit))
1003                return ret;
1004        for (i = 0; i < nr_reference; i++)
1005                if (parse_commit(reference[i]))
1006                        return ret;
1007
1008        bases = paint_down_to_common(commit, nr_reference, reference);
1009        if (commit->object.flags & PARENT2)
1010                ret = 1;
1011        clear_commit_marks(commit, all_flags);
1012        clear_commit_marks_many(nr_reference, reference, all_flags);
1013        free_commit_list(bases);
1014        return ret;
1015}
1016
1017/*
1018 * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
1019 */
1020int in_merge_bases(struct commit *commit, struct commit *reference)
1021{
1022        return in_merge_bases_many(commit, 1, &reference);
1023}
1024
1025struct commit_list *reduce_heads(struct commit_list *heads)
1026{
1027        struct commit_list *p;
1028        struct commit_list *result = NULL, **tail = &result;
1029        struct commit **array;
1030        int num_head, i;
1031
1032        if (!heads)
1033                return NULL;
1034
1035        /* Uniquify */
1036        for (p = heads; p; p = p->next)
1037                p->item->object.flags &= ~STALE;
1038        for (p = heads, num_head = 0; p; p = p->next) {
1039                if (p->item->object.flags & STALE)
1040                        continue;
1041                p->item->object.flags |= STALE;
1042                num_head++;
1043        }
1044        array = xcalloc(sizeof(*array), num_head);
1045        for (p = heads, i = 0; p; p = p->next) {
1046                if (p->item->object.flags & STALE) {
1047                        array[i++] = p->item;
1048                        p->item->object.flags &= ~STALE;
1049                }
1050        }
1051        num_head = remove_redundant(array, num_head);
1052        for (i = 0; i < num_head; i++)
1053                tail = &commit_list_insert(array[i], tail)->next;
1054        return result;
1055}
1056
1057static const char gpg_sig_header[] = "gpgsig";
1058static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1059
1060static int do_sign_commit(struct strbuf *buf, const char *keyid)
1061{
1062        struct strbuf sig = STRBUF_INIT;
1063        int inspos, copypos;
1064
1065        /* find the end of the header */
1066        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1067
1068        if (!keyid || !*keyid)
1069                keyid = get_signing_key();
1070        if (sign_buffer(buf, &sig, keyid)) {
1071                strbuf_release(&sig);
1072                return -1;
1073        }
1074
1075        for (copypos = 0; sig.buf[copypos]; ) {
1076                const char *bol = sig.buf + copypos;
1077                const char *eol = strchrnul(bol, '\n');
1078                int len = (eol - bol) + !!*eol;
1079
1080                if (!copypos) {
1081                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1082                        inspos += gpg_sig_header_len;
1083                }
1084                strbuf_insert(buf, inspos++, " ", 1);
1085                strbuf_insert(buf, inspos, bol, len);
1086                inspos += len;
1087                copypos += len;
1088        }
1089        strbuf_release(&sig);
1090        return 0;
1091}
1092
1093int parse_signed_commit(const unsigned char *sha1,
1094                        struct strbuf *payload, struct strbuf *signature)
1095{
1096        unsigned long size;
1097        enum object_type type;
1098        char *buffer = read_sha1_file(sha1, &type, &size);
1099        int in_signature, saw_signature = -1;
1100        char *line, *tail;
1101
1102        if (!buffer || type != OBJ_COMMIT)
1103                goto cleanup;
1104
1105        line = buffer;
1106        tail = buffer + size;
1107        in_signature = 0;
1108        saw_signature = 0;
1109        while (line < tail) {
1110                const char *sig = NULL;
1111                char *next = memchr(line, '\n', tail - line);
1112
1113                next = next ? next + 1 : tail;
1114                if (in_signature && line[0] == ' ')
1115                        sig = line + 1;
1116                else if (starts_with(line, gpg_sig_header) &&
1117                         line[gpg_sig_header_len] == ' ')
1118                        sig = line + gpg_sig_header_len + 1;
1119                if (sig) {
1120                        strbuf_add(signature, sig, next - sig);
1121                        saw_signature = 1;
1122                        in_signature = 1;
1123                } else {
1124                        if (*line == '\n')
1125                                /* dump the whole remainder of the buffer */
1126                                next = tail;
1127                        strbuf_add(payload, line, next - line);
1128                        in_signature = 0;
1129                }
1130                line = next;
1131        }
1132 cleanup:
1133        free(buffer);
1134        return saw_signature;
1135}
1136
1137static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1138{
1139        struct merge_remote_desc *desc;
1140        struct commit_extra_header *mergetag;
1141        char *buf;
1142        unsigned long size, len;
1143        enum object_type type;
1144
1145        desc = merge_remote_util(parent);
1146        if (!desc || !desc->obj)
1147                return;
1148        buf = read_sha1_file(desc->obj->sha1, &type, &size);
1149        if (!buf || type != OBJ_TAG)
1150                goto free_return;
1151        len = parse_signature(buf, size);
1152        if (size == len)
1153                goto free_return;
1154        /*
1155         * We could verify this signature and either omit the tag when
1156         * it does not validate, but the integrator may not have the
1157         * public key of the signer of the tag he is merging, while a
1158         * later auditor may have it while auditing, so let's not run
1159         * verify-signed-buffer here for now...
1160         *
1161         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1162         *      warn("warning: signed tag unverified.");
1163         */
1164        mergetag = xcalloc(1, sizeof(*mergetag));
1165        mergetag->key = xstrdup("mergetag");
1166        mergetag->value = buf;
1167        mergetag->len = size;
1168
1169        **tail = mergetag;
1170        *tail = &mergetag->next;
1171        return;
1172
1173free_return:
1174        free(buf);
1175}
1176
1177static struct {
1178        char result;
1179        const char *check;
1180} sigcheck_gpg_status[] = {
1181        { 'G', "\n[GNUPG:] GOODSIG " },
1182        { 'B', "\n[GNUPG:] BADSIG " },
1183        { 'U', "\n[GNUPG:] TRUST_NEVER" },
1184        { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1185};
1186
1187static void parse_gpg_output(struct signature_check *sigc)
1188{
1189        const char *buf = sigc->gpg_status;
1190        int i;
1191
1192        /* Iterate over all search strings */
1193        for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1194                const char *found, *next;
1195
1196                if (starts_with(buf, sigcheck_gpg_status[i].check + 1)) {
1197                        /* At the very beginning of the buffer */
1198                        found = buf + strlen(sigcheck_gpg_status[i].check + 1);
1199                } else {
1200                        found = strstr(buf, sigcheck_gpg_status[i].check);
1201                        if (!found)
1202                                continue;
1203                        found += strlen(sigcheck_gpg_status[i].check);
1204                }
1205                sigc->result = sigcheck_gpg_status[i].result;
1206                /* The trust messages are not followed by key/signer information */
1207                if (sigc->result != 'U') {
1208                        sigc->key = xmemdupz(found, 16);
1209                        found += 17;
1210                        next = strchrnul(found, '\n');
1211                        sigc->signer = xmemdupz(found, next - found);
1212                }
1213        }
1214}
1215
1216void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1217{
1218        struct strbuf payload = STRBUF_INIT;
1219        struct strbuf signature = STRBUF_INIT;
1220        struct strbuf gpg_output = STRBUF_INIT;
1221        struct strbuf gpg_status = STRBUF_INIT;
1222        int status;
1223
1224        sigc->result = 'N';
1225
1226        if (parse_signed_commit(commit->object.sha1,
1227                                &payload, &signature) <= 0)
1228                goto out;
1229        status = verify_signed_buffer(payload.buf, payload.len,
1230                                      signature.buf, signature.len,
1231                                      &gpg_output, &gpg_status);
1232        if (status && !gpg_output.len)
1233                goto out;
1234        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1235        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1236        parse_gpg_output(sigc);
1237
1238 out:
1239        strbuf_release(&gpg_status);
1240        strbuf_release(&gpg_output);
1241        strbuf_release(&payload);
1242        strbuf_release(&signature);
1243}
1244
1245
1246
1247void append_merge_tag_headers(struct commit_list *parents,
1248                              struct commit_extra_header ***tail)
1249{
1250        while (parents) {
1251                struct commit *parent = parents->item;
1252                handle_signed_tag(parent, tail);
1253                parents = parents->next;
1254        }
1255}
1256
1257static void add_extra_header(struct strbuf *buffer,
1258                             struct commit_extra_header *extra)
1259{
1260        strbuf_addstr(buffer, extra->key);
1261        if (extra->len)
1262                strbuf_add_lines(buffer, " ", extra->value, extra->len);
1263        else
1264                strbuf_addch(buffer, '\n');
1265}
1266
1267struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1268                                                      const char **exclude)
1269{
1270        struct commit_extra_header *extra = NULL;
1271        unsigned long size;
1272        enum object_type type;
1273        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1274        if (buffer && type == OBJ_COMMIT)
1275                extra = read_commit_extra_header_lines(buffer, size, exclude);
1276        free(buffer);
1277        return extra;
1278}
1279
1280static inline int standard_header_field(const char *field, size_t len)
1281{
1282        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1283                (len == 6 && !memcmp(field, "parent ", 7)) ||
1284                (len == 6 && !memcmp(field, "author ", 7)) ||
1285                (len == 9 && !memcmp(field, "committer ", 10)) ||
1286                (len == 8 && !memcmp(field, "encoding ", 9)));
1287}
1288
1289static int excluded_header_field(const char *field, size_t len, const char **exclude)
1290{
1291        if (!exclude)
1292                return 0;
1293
1294        while (*exclude) {
1295                size_t xlen = strlen(*exclude);
1296                if (len == xlen &&
1297                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1298                        return 1;
1299                exclude++;
1300        }
1301        return 0;
1302}
1303
1304static struct commit_extra_header *read_commit_extra_header_lines(
1305        const char *buffer, size_t size,
1306        const char **exclude)
1307{
1308        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1309        const char *line, *next, *eof, *eob;
1310        struct strbuf buf = STRBUF_INIT;
1311
1312        for (line = buffer, eob = line + size;
1313             line < eob && *line != '\n';
1314             line = next) {
1315                next = memchr(line, '\n', eob - line);
1316                next = next ? next + 1 : eob;
1317                if (*line == ' ') {
1318                        /* continuation */
1319                        if (it)
1320                                strbuf_add(&buf, line + 1, next - (line + 1));
1321                        continue;
1322                }
1323                if (it)
1324                        it->value = strbuf_detach(&buf, &it->len);
1325                strbuf_reset(&buf);
1326                it = NULL;
1327
1328                eof = strchr(line, ' ');
1329                if (next <= eof)
1330                        eof = next;
1331
1332                if (standard_header_field(line, eof - line) ||
1333                    excluded_header_field(line, eof - line, exclude))
1334                        continue;
1335
1336                it = xcalloc(1, sizeof(*it));
1337                it->key = xmemdupz(line, eof-line);
1338                *tail = it;
1339                tail = &it->next;
1340                if (eof + 1 < next)
1341                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1342        }
1343        if (it)
1344                it->value = strbuf_detach(&buf, &it->len);
1345        return extra;
1346}
1347
1348void free_commit_extra_headers(struct commit_extra_header *extra)
1349{
1350        while (extra) {
1351                struct commit_extra_header *next = extra->next;
1352                free(extra->key);
1353                free(extra->value);
1354                free(extra);
1355                extra = next;
1356        }
1357}
1358
1359int commit_tree(const struct strbuf *msg, const unsigned char *tree,
1360                struct commit_list *parents, unsigned char *ret,
1361                const char *author, const char *sign_commit)
1362{
1363        struct commit_extra_header *extra = NULL, **tail = &extra;
1364        int result;
1365
1366        append_merge_tag_headers(parents, &tail);
1367        result = commit_tree_extended(msg, tree, parents, ret,
1368                                      author, sign_commit, extra);
1369        free_commit_extra_headers(extra);
1370        return result;
1371}
1372
1373static int find_invalid_utf8(const char *buf, int len)
1374{
1375        int offset = 0;
1376        static const unsigned int max_codepoint[] = {
1377                0x7f, 0x7ff, 0xffff, 0x10ffff
1378        };
1379
1380        while (len) {
1381                unsigned char c = *buf++;
1382                int bytes, bad_offset;
1383                unsigned int codepoint;
1384                unsigned int min_val, max_val;
1385
1386                len--;
1387                offset++;
1388
1389                /* Simple US-ASCII? No worries. */
1390                if (c < 0x80)
1391                        continue;
1392
1393                bad_offset = offset-1;
1394
1395                /*
1396                 * Count how many more high bits set: that's how
1397                 * many more bytes this sequence should have.
1398                 */
1399                bytes = 0;
1400                while (c & 0x40) {
1401                        c <<= 1;
1402                        bytes++;
1403                }
1404
1405                /*
1406                 * Must be between 1 and 3 more bytes.  Longer sequences result in
1407                 * codepoints beyond U+10FFFF, which are guaranteed never to exist.
1408                 */
1409                if (bytes < 1 || 3 < bytes)
1410                        return bad_offset;
1411
1412                /* Do we *have* that many bytes? */
1413                if (len < bytes)
1414                        return bad_offset;
1415
1416                /*
1417                 * Place the encoded bits at the bottom of the value and compute the
1418                 * valid range.
1419                 */
1420                codepoint = (c & 0x7f) >> bytes;
1421                min_val = max_codepoint[bytes-1] + 1;
1422                max_val = max_codepoint[bytes];
1423
1424                offset += bytes;
1425                len -= bytes;
1426
1427                /* And verify that they are good continuation bytes */
1428                do {
1429                        codepoint <<= 6;
1430                        codepoint |= *buf & 0x3f;
1431                        if ((*buf++ & 0xc0) != 0x80)
1432                                return bad_offset;
1433                } while (--bytes);
1434
1435                /* Reject codepoints that are out of range for the sequence length. */
1436                if (codepoint < min_val || codepoint > max_val)
1437                        return bad_offset;
1438                /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
1439                if ((codepoint & 0x1ff800) == 0xd800)
1440                        return bad_offset;
1441                /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
1442                if ((codepoint & 0xfffe) == 0xfffe)
1443                        return bad_offset;
1444                /* So are anything in the range U+FDD0..U+FDEF. */
1445                if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
1446                        return bad_offset;
1447        }
1448        return -1;
1449}
1450
1451/*
1452 * This verifies that the buffer is in proper utf8 format.
1453 *
1454 * If it isn't, it assumes any non-utf8 characters are Latin1,
1455 * and does the conversion.
1456 */
1457static int verify_utf8(struct strbuf *buf)
1458{
1459        int ok = 1;
1460        long pos = 0;
1461
1462        for (;;) {
1463                int bad;
1464                unsigned char c;
1465                unsigned char replace[2];
1466
1467                bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1468                if (bad < 0)
1469                        return ok;
1470                pos += bad;
1471                ok = 0;
1472                c = buf->buf[pos];
1473                strbuf_remove(buf, pos, 1);
1474
1475                /* We know 'c' must be in the range 128-255 */
1476                replace[0] = 0xc0 + (c >> 6);
1477                replace[1] = 0x80 + (c & 0x3f);
1478                strbuf_insert(buf, pos, replace, 2);
1479                pos += 2;
1480        }
1481}
1482
1483static const char commit_utf8_warn[] =
1484"Warning: commit message did not conform to UTF-8.\n"
1485"You may want to amend it after fixing the message, or set the config\n"
1486"variable i18n.commitencoding to the encoding your project uses.\n";
1487
1488int commit_tree_extended(const struct strbuf *msg, const unsigned char *tree,
1489                         struct commit_list *parents, unsigned char *ret,
1490                         const char *author, const char *sign_commit,
1491                         struct commit_extra_header *extra)
1492{
1493        int result;
1494        int encoding_is_utf8;
1495        struct strbuf buffer;
1496
1497        assert_sha1_type(tree, OBJ_TREE);
1498
1499        if (memchr(msg->buf, '\0', msg->len))
1500                return error("a NUL byte in commit log message not allowed.");
1501
1502        /* Not having i18n.commitencoding is the same as having utf-8 */
1503        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1504
1505        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1506        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1507
1508        /*
1509         * NOTE! This ordering means that the same exact tree merged with a
1510         * different order of parents will be a _different_ changeset even
1511         * if everything else stays the same.
1512         */
1513        while (parents) {
1514                struct commit_list *next = parents->next;
1515                struct commit *parent = parents->item;
1516
1517                strbuf_addf(&buffer, "parent %s\n",
1518                            sha1_to_hex(parent->object.sha1));
1519                free(parents);
1520                parents = next;
1521        }
1522
1523        /* Person/date information */
1524        if (!author)
1525                author = git_author_info(IDENT_STRICT);
1526        strbuf_addf(&buffer, "author %s\n", author);
1527        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1528        if (!encoding_is_utf8)
1529                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1530
1531        while (extra) {
1532                add_extra_header(&buffer, extra);
1533                extra = extra->next;
1534        }
1535        strbuf_addch(&buffer, '\n');
1536
1537        /* And add the comment */
1538        strbuf_addbuf(&buffer, msg);
1539
1540        /* And check the encoding */
1541        if (encoding_is_utf8 && !verify_utf8(&buffer))
1542                fprintf(stderr, commit_utf8_warn);
1543
1544        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1545                return -1;
1546
1547        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1548        strbuf_release(&buffer);
1549        return result;
1550}
1551
1552struct commit *get_merge_parent(const char *name)
1553{
1554        struct object *obj;
1555        struct commit *commit;
1556        unsigned char sha1[20];
1557        if (get_sha1(name, sha1))
1558                return NULL;
1559        obj = parse_object(sha1);
1560        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1561        if (commit && !commit->util) {
1562                struct merge_remote_desc *desc;
1563                desc = xmalloc(sizeof(*desc));
1564                desc->obj = obj;
1565                desc->name = strdup(name);
1566                commit->util = desc;
1567        }
1568        return commit;
1569}
1570
1571/*
1572 * Append a commit to the end of the commit_list.
1573 *
1574 * next starts by pointing to the variable that holds the head of an
1575 * empty commit_list, and is updated to point to the "next" field of
1576 * the last item on the list as new commits are appended.
1577 *
1578 * Usage example:
1579 *
1580 *     struct commit_list *list;
1581 *     struct commit_list **next = &list;
1582 *
1583 *     next = commit_list_append(c1, next);
1584 *     next = commit_list_append(c2, next);
1585 *     assert(commit_list_count(list) == 2);
1586 *     return list;
1587 */
1588struct commit_list **commit_list_append(struct commit *commit,
1589                                        struct commit_list **next)
1590{
1591        struct commit_list *new = xmalloc(sizeof(struct commit_list));
1592        new->item = commit;
1593        *next = new;
1594        new->next = NULL;
1595        return &new->next;
1596}
1597
1598void print_commit_list(struct commit_list *list,
1599                       const char *format_cur,
1600                       const char *format_last)
1601{
1602        for ( ; list; list = list->next) {
1603                const char *format = list->next ? format_cur : format_last;
1604                printf(format, sha1_to_hex(list->item->object.sha1));
1605        }
1606}