Andrew's git / gitweb.git / commit.c
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commit.con commit use skip_prefix to avoid magic numbers (ae021d8)
   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#include "sha1-lookup.h"
  14
  15static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  16
  17int save_commit_buffer = 1;
  18
  19const char *commit_type = "commit";
  20static int commit_count;
  21
  22static struct commit *check_commit(struct object *obj,
  23                                   const unsigned char *sha1,
  24                                   int quiet)
  25{
  26        if (obj->type != OBJ_COMMIT) {
  27                if (!quiet)
  28                        error("Object %s is a %s, not a commit",
  29                              sha1_to_hex(sha1), typename(obj->type));
  30                return NULL;
  31        }
  32        return (struct commit *) obj;
  33}
  34
  35struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  36                                              int quiet)
  37{
  38        struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  39
  40        if (!obj)
  41                return NULL;
  42        return check_commit(obj, sha1, quiet);
  43}
  44
  45struct commit *lookup_commit_reference(const unsigned char *sha1)
  46{
  47        return lookup_commit_reference_gently(sha1, 0);
  48}
  49
  50struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  51{
  52        struct commit *c = lookup_commit_reference(sha1);
  53        if (!c)
  54                die(_("could not parse %s"), ref_name);
  55        if (hashcmp(sha1, c->object.sha1)) {
  56                warning(_("%s %s is not a commit!"),
  57                        ref_name, sha1_to_hex(sha1));
  58        }
  59        return c;
  60}
  61
  62struct commit *lookup_commit(const unsigned char *sha1)
  63{
  64        struct object *obj = lookup_object(sha1);
  65        if (!obj) {
  66                struct commit *c = alloc_commit_node();
  67                c->index = commit_count++;
  68                return create_object(sha1, OBJ_COMMIT, c);
  69        }
  70        if (!obj->type)
  71                obj->type = OBJ_COMMIT;
  72        return check_commit(obj, sha1, 0);
  73}
  74
  75struct commit *lookup_commit_reference_by_name(const char *name)
  76{
  77        unsigned char sha1[20];
  78        struct commit *commit;
  79
  80        if (get_sha1_committish(name, sha1))
  81                return NULL;
  82        commit = lookup_commit_reference(sha1);
  83        if (parse_commit(commit))
  84                return NULL;
  85        return commit;
  86}
  87
  88static unsigned long parse_commit_date(const char *buf, const char *tail)
  89{
  90        const char *dateptr;
  91
  92        if (buf + 6 >= tail)
  93                return 0;
  94        if (memcmp(buf, "author", 6))
  95                return 0;
  96        while (buf < tail && *buf++ != '\n')
  97                /* nada */;
  98        if (buf + 9 >= tail)
  99                return 0;
 100        if (memcmp(buf, "committer", 9))
 101                return 0;
 102        while (buf < tail && *buf++ != '>')
 103                /* nada */;
 104        if (buf >= tail)
 105                return 0;
 106        dateptr = buf;
 107        while (buf < tail && *buf++ != '\n')
 108                /* nada */;
 109        if (buf >= tail)
 110                return 0;
 111        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 112        return strtoul(dateptr, NULL, 10);
 113}
 114
 115static struct commit_graft **commit_graft;
 116static int commit_graft_alloc, commit_graft_nr;
 117
 118static const unsigned char *commit_graft_sha1_access(size_t index, void *table)
 119{
 120        struct commit_graft **commit_graft_table = table;
 121        return commit_graft_table[index]->sha1;
 122}
 123
 124static int commit_graft_pos(const unsigned char *sha1)
 125{
 126        return sha1_pos(sha1, commit_graft, commit_graft_nr,
 127                        commit_graft_sha1_access);
 128}
 129
 130int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 131{
 132        int pos = commit_graft_pos(graft->sha1);
 133
 134        if (0 <= pos) {
 135                if (ignore_dups)
 136                        free(graft);
 137                else {
 138                        free(commit_graft[pos]);
 139                        commit_graft[pos] = graft;
 140                }
 141                return 1;
 142        }
 143        pos = -pos - 1;
 144        ALLOC_GROW(commit_graft, commit_graft_nr + 1, commit_graft_alloc);
 145        commit_graft_nr++;
 146        if (pos < commit_graft_nr)
 147                memmove(commit_graft + pos + 1,
 148                        commit_graft + pos,
 149                        (commit_graft_nr - pos - 1) *
 150                        sizeof(*commit_graft));
 151        commit_graft[pos] = graft;
 152        return 0;
 153}
 154
 155struct commit_graft *read_graft_line(char *buf, int len)
 156{
 157        /* The format is just "Commit Parent1 Parent2 ...\n" */
 158        int i;
 159        struct commit_graft *graft = NULL;
 160
 161        while (len && isspace(buf[len-1]))
 162                buf[--len] = '\0';
 163        if (buf[0] == '#' || buf[0] == '\0')
 164                return NULL;
 165        if ((len + 1) % 41)
 166                goto bad_graft_data;
 167        i = (len + 1) / 41 - 1;
 168        graft = xmalloc(sizeof(*graft) + 20 * i);
 169        graft->nr_parent = i;
 170        if (get_sha1_hex(buf, graft->sha1))
 171                goto bad_graft_data;
 172        for (i = 40; i < len; i += 41) {
 173                if (buf[i] != ' ')
 174                        goto bad_graft_data;
 175                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 176                        goto bad_graft_data;
 177        }
 178        return graft;
 179
 180bad_graft_data:
 181        error("bad graft data: %s", buf);
 182        free(graft);
 183        return NULL;
 184}
 185
 186static int read_graft_file(const char *graft_file)
 187{
 188        FILE *fp = fopen(graft_file, "r");
 189        struct strbuf buf = STRBUF_INIT;
 190        if (!fp)
 191                return -1;
 192        while (!strbuf_getwholeline(&buf, fp, '\n')) {
 193                /* The format is just "Commit Parent1 Parent2 ...\n" */
 194                struct commit_graft *graft = read_graft_line(buf.buf, buf.len);
 195                if (!graft)
 196                        continue;
 197                if (register_commit_graft(graft, 1))
 198                        error("duplicate graft data: %s", buf.buf);
 199        }
 200        fclose(fp);
 201        strbuf_release(&buf);
 202        return 0;
 203}
 204
 205static void prepare_commit_graft(void)
 206{
 207        static int commit_graft_prepared;
 208        char *graft_file;
 209
 210        if (commit_graft_prepared)
 211                return;
 212        graft_file = get_graft_file();
 213        read_graft_file(graft_file);
 214        /* make sure shallows are read */
 215        is_repository_shallow();
 216        commit_graft_prepared = 1;
 217}
 218
 219struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 220{
 221        int pos;
 222        prepare_commit_graft();
 223        pos = commit_graft_pos(sha1);
 224        if (pos < 0)
 225                return NULL;
 226        return commit_graft[pos];
 227}
 228
 229int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 230{
 231        int i, ret;
 232        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 233                ret = fn(commit_graft[i], cb_data);
 234        return ret;
 235}
 236
 237int unregister_shallow(const unsigned char *sha1)
 238{
 239        int pos = commit_graft_pos(sha1);
 240        if (pos < 0)
 241                return -1;
 242        if (pos + 1 < commit_graft_nr)
 243                memmove(commit_graft + pos, commit_graft + pos + 1,
 244                                sizeof(struct commit_graft *)
 245                                * (commit_graft_nr - pos - 1));
 246        commit_graft_nr--;
 247        return 0;
 248}
 249
 250int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 251{
 252        const char *tail = buffer;
 253        const char *bufptr = buffer;
 254        unsigned char parent[20];
 255        struct commit_list **pptr;
 256        struct commit_graft *graft;
 257
 258        if (item->object.parsed)
 259                return 0;
 260        item->object.parsed = 1;
 261        tail += size;
 262        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 263                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 264        if (get_sha1_hex(bufptr + 5, parent) < 0)
 265                return error("bad tree pointer in commit %s",
 266                             sha1_to_hex(item->object.sha1));
 267        item->tree = lookup_tree(parent);
 268        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 269        pptr = &item->parents;
 270
 271        graft = lookup_commit_graft(item->object.sha1);
 272        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 273                struct commit *new_parent;
 274
 275                if (tail <= bufptr + 48 ||
 276                    get_sha1_hex(bufptr + 7, parent) ||
 277                    bufptr[47] != '\n')
 278                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 279                bufptr += 48;
 280                /*
 281                 * The clone is shallow if nr_parent < 0, and we must
 282                 * not traverse its real parents even when we unhide them.
 283                 */
 284                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 285                        continue;
 286                new_parent = lookup_commit(parent);
 287                if (new_parent)
 288                        pptr = &commit_list_insert(new_parent, pptr)->next;
 289        }
 290        if (graft) {
 291                int i;
 292                struct commit *new_parent;
 293                for (i = 0; i < graft->nr_parent; i++) {
 294                        new_parent = lookup_commit(graft->parent[i]);
 295                        if (!new_parent)
 296                                continue;
 297                        pptr = &commit_list_insert(new_parent, pptr)->next;
 298                }
 299        }
 300        item->date = parse_commit_date(bufptr, tail);
 301
 302        return 0;
 303}
 304
 305int parse_commit(struct commit *item)
 306{
 307        enum object_type type;
 308        void *buffer;
 309        unsigned long size;
 310        int ret;
 311
 312        if (!item)
 313                return -1;
 314        if (item->object.parsed)
 315                return 0;
 316        buffer = read_sha1_file(item->object.sha1, &type, &size);
 317        if (!buffer)
 318                return error("Could not read %s",
 319                             sha1_to_hex(item->object.sha1));
 320        if (type != OBJ_COMMIT) {
 321                free(buffer);
 322                return error("Object %s not a commit",
 323                             sha1_to_hex(item->object.sha1));
 324        }
 325        ret = parse_commit_buffer(item, buffer, size);
 326        if (save_commit_buffer && !ret) {
 327                item->buffer = buffer;
 328                return 0;
 329        }
 330        free(buffer);
 331        return ret;
 332}
 333
 334void parse_commit_or_die(struct commit *item)
 335{
 336        if (parse_commit(item))
 337                die("unable to parse commit %s",
 338                    item ? sha1_to_hex(item->object.sha1) : "(null)");
 339}
 340
 341int find_commit_subject(const char *commit_buffer, const char **subject)
 342{
 343        const char *eol;
 344        const char *p = commit_buffer;
 345
 346        while (*p && (*p != '\n' || p[1] != '\n'))
 347                p++;
 348        if (*p) {
 349                p += 2;
 350                for (eol = p; *eol && *eol != '\n'; eol++)
 351                        ; /* do nothing */
 352        } else
 353                eol = p;
 354
 355        *subject = p;
 356
 357        return eol - p;
 358}
 359
 360struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 361{
 362        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 363        new_list->item = item;
 364        new_list->next = *list_p;
 365        *list_p = new_list;
 366        return new_list;
 367}
 368
 369unsigned commit_list_count(const struct commit_list *l)
 370{
 371        unsigned c = 0;
 372        for (; l; l = l->next )
 373                c++;
 374        return c;
 375}
 376
 377struct commit_list *copy_commit_list(struct commit_list *list)
 378{
 379        struct commit_list *head = NULL;
 380        struct commit_list **pp = &head;
 381        while (list) {
 382                struct commit_list *new;
 383                new = xmalloc(sizeof(struct commit_list));
 384                new->item = list->item;
 385                new->next = NULL;
 386                *pp = new;
 387                pp = &new->next;
 388                list = list->next;
 389        }
 390        return head;
 391}
 392
 393void free_commit_list(struct commit_list *list)
 394{
 395        while (list) {
 396                struct commit_list *temp = list;
 397                list = temp->next;
 398                free(temp);
 399        }
 400}
 401
 402struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 403{
 404        struct commit_list **pp = list;
 405        struct commit_list *p;
 406        while ((p = *pp) != NULL) {
 407                if (p->item->date < item->date) {
 408                        break;
 409                }
 410                pp = &p->next;
 411        }
 412        return commit_list_insert(item, pp);
 413}
 414
 415static int commit_list_compare_by_date(const void *a, const void *b)
 416{
 417        unsigned long a_date = ((const struct commit_list *)a)->item->date;
 418        unsigned long b_date = ((const struct commit_list *)b)->item->date;
 419        if (a_date < b_date)
 420                return 1;
 421        if (a_date > b_date)
 422                return -1;
 423        return 0;
 424}
 425
 426static void *commit_list_get_next(const void *a)
 427{
 428        return ((const struct commit_list *)a)->next;
 429}
 430
 431static void commit_list_set_next(void *a, void *next)
 432{
 433        ((struct commit_list *)a)->next = next;
 434}
 435
 436void commit_list_sort_by_date(struct commit_list **list)
 437{
 438        *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 439                                commit_list_compare_by_date);
 440}
 441
 442struct commit *pop_most_recent_commit(struct commit_list **list,
 443                                      unsigned int mark)
 444{
 445        struct commit *ret = (*list)->item;
 446        struct commit_list *parents = ret->parents;
 447        struct commit_list *old = *list;
 448
 449        *list = (*list)->next;
 450        free(old);
 451
 452        while (parents) {
 453                struct commit *commit = parents->item;
 454                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 455                        commit->object.flags |= mark;
 456                        commit_list_insert_by_date(commit, list);
 457                }
 458                parents = parents->next;
 459        }
 460        return ret;
 461}
 462
 463static void clear_commit_marks_1(struct commit_list **plist,
 464                                 struct commit *commit, unsigned int mark)
 465{
 466        while (commit) {
 467                struct commit_list *parents;
 468
 469                if (!(mark & commit->object.flags))
 470                        return;
 471
 472                commit->object.flags &= ~mark;
 473
 474                parents = commit->parents;
 475                if (!parents)
 476                        return;
 477
 478                while ((parents = parents->next))
 479                        commit_list_insert(parents->item, plist);
 480
 481                commit = commit->parents->item;
 482        }
 483}
 484
 485void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 486{
 487        struct commit_list *list = NULL;
 488
 489        while (nr--) {
 490                commit_list_insert(*commit, &list);
 491                commit++;
 492        }
 493        while (list)
 494                clear_commit_marks_1(&list, pop_commit(&list), mark);
 495}
 496
 497void clear_commit_marks(struct commit *commit, unsigned int mark)
 498{
 499        clear_commit_marks_many(1, &commit, mark);
 500}
 501
 502void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 503{
 504        struct object *object;
 505        struct commit *commit;
 506        unsigned int i;
 507
 508        for (i = 0; i < a->nr; i++) {
 509                object = a->objects[i].item;
 510                commit = lookup_commit_reference_gently(object->sha1, 1);
 511                if (commit)
 512                        clear_commit_marks(commit, mark);
 513        }
 514}
 515
 516struct commit *pop_commit(struct commit_list **stack)
 517{
 518        struct commit_list *top = *stack;
 519        struct commit *item = top ? top->item : NULL;
 520
 521        if (top) {
 522                *stack = top->next;
 523                free(top);
 524        }
 525        return item;
 526}
 527
 528/*
 529 * Topological sort support
 530 */
 531
 532/* count number of children that have not been emitted */
 533define_commit_slab(indegree_slab, int);
 534
 535/* record author-date for each commit object */
 536define_commit_slab(author_date_slab, unsigned long);
 537
 538static void record_author_date(struct author_date_slab *author_date,
 539                               struct commit *commit)
 540{
 541        const char *buf, *line_end, *ident_line;
 542        char *buffer = NULL;
 543        struct ident_split ident;
 544        char *date_end;
 545        unsigned long date;
 546
 547        if (!commit->buffer) {
 548                unsigned long size;
 549                enum object_type type;
 550                buffer = read_sha1_file(commit->object.sha1, &type, &size);
 551                if (!buffer)
 552                        return;
 553        }
 554
 555        for (buf = commit->buffer ? commit->buffer : buffer;
 556             buf;
 557             buf = line_end + 1) {
 558                line_end = strchrnul(buf, '\n');
 559                if (!skip_prefix(buf, "author ", &ident_line)) {
 560                        if (!line_end[0] || line_end[1] == '\n')
 561                                return; /* end of header */
 562                        continue;
 563                }
 564                if (split_ident_line(&ident,
 565                                     ident_line, line_end - ident_line) ||
 566                    !ident.date_begin || !ident.date_end)
 567                        goto fail_exit; /* malformed "author" line */
 568                break;
 569        }
 570
 571        date = strtoul(ident.date_begin, &date_end, 10);
 572        if (date_end != ident.date_end)
 573                goto fail_exit; /* malformed date */
 574        *(author_date_slab_at(author_date, commit)) = date;
 575
 576fail_exit:
 577        free(buffer);
 578}
 579
 580static int compare_commits_by_author_date(const void *a_, const void *b_,
 581                                          void *cb_data)
 582{
 583        const struct commit *a = a_, *b = b_;
 584        struct author_date_slab *author_date = cb_data;
 585        unsigned long a_date = *(author_date_slab_at(author_date, a));
 586        unsigned long b_date = *(author_date_slab_at(author_date, b));
 587
 588        /* newer commits with larger date first */
 589        if (a_date < b_date)
 590                return 1;
 591        else if (a_date > b_date)
 592                return -1;
 593        return 0;
 594}
 595
 596int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 597{
 598        const struct commit *a = a_, *b = b_;
 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
 607/*
 608 * Performs an in-place topological sort on the list supplied.
 609 */
 610void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 611{
 612        struct commit_list *next, *orig = *list;
 613        struct commit_list **pptr;
 614        struct indegree_slab indegree;
 615        struct prio_queue queue;
 616        struct commit *commit;
 617        struct author_date_slab author_date;
 618
 619        if (!orig)
 620                return;
 621        *list = NULL;
 622
 623        init_indegree_slab(&indegree);
 624        memset(&queue, '\0', sizeof(queue));
 625
 626        switch (sort_order) {
 627        default: /* REV_SORT_IN_GRAPH_ORDER */
 628                queue.compare = NULL;
 629                break;
 630        case REV_SORT_BY_COMMIT_DATE:
 631                queue.compare = compare_commits_by_commit_date;
 632                break;
 633        case REV_SORT_BY_AUTHOR_DATE:
 634                init_author_date_slab(&author_date);
 635                queue.compare = compare_commits_by_author_date;
 636                queue.cb_data = &author_date;
 637                break;
 638        }
 639
 640        /* Mark them and clear the indegree */
 641        for (next = orig; next; next = next->next) {
 642                struct commit *commit = next->item;
 643                *(indegree_slab_at(&indegree, commit)) = 1;
 644                /* also record the author dates, if needed */
 645                if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 646                        record_author_date(&author_date, commit);
 647        }
 648
 649        /* update the indegree */
 650        for (next = orig; next; next = next->next) {
 651                struct commit_list *parents = next->item->parents;
 652                while (parents) {
 653                        struct commit *parent = parents->item;
 654                        int *pi = indegree_slab_at(&indegree, parent);
 655
 656                        if (*pi)
 657                                (*pi)++;
 658                        parents = parents->next;
 659                }
 660        }
 661
 662        /*
 663         * find the tips
 664         *
 665         * tips are nodes not reachable from any other node in the list
 666         *
 667         * the tips serve as a starting set for the work queue.
 668         */
 669        for (next = orig; next; next = next->next) {
 670                struct commit *commit = next->item;
 671
 672                if (*(indegree_slab_at(&indegree, commit)) == 1)
 673                        prio_queue_put(&queue, commit);
 674        }
 675
 676        /*
 677         * This is unfortunate; the initial tips need to be shown
 678         * in the order given from the revision traversal machinery.
 679         */
 680        if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 681                prio_queue_reverse(&queue);
 682
 683        /* We no longer need the commit list */
 684        free_commit_list(orig);
 685
 686        pptr = list;
 687        *list = NULL;
 688        while ((commit = prio_queue_get(&queue)) != NULL) {
 689                struct commit_list *parents;
 690
 691                for (parents = commit->parents; parents ; parents = parents->next) {
 692                        struct commit *parent = parents->item;
 693                        int *pi = indegree_slab_at(&indegree, parent);
 694
 695                        if (!*pi)
 696                                continue;
 697
 698                        /*
 699                         * parents are only enqueued for emission
 700                         * when all their children have been emitted thereby
 701                         * guaranteeing topological order.
 702                         */
 703                        if (--(*pi) == 1)
 704                                prio_queue_put(&queue, parent);
 705                }
 706                /*
 707                 * all children of commit have already been
 708                 * emitted. we can emit it now.
 709                 */
 710                *(indegree_slab_at(&indegree, commit)) = 0;
 711
 712                pptr = &commit_list_insert(commit, pptr)->next;
 713        }
 714
 715        clear_indegree_slab(&indegree);
 716        clear_prio_queue(&queue);
 717        if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 718                clear_author_date_slab(&author_date);
 719}
 720
 721/* merge-base stuff */
 722
 723/* Remember to update object flag allocation in object.h */
 724#define PARENT1         (1u<<16)
 725#define PARENT2         (1u<<17)
 726#define STALE           (1u<<18)
 727#define RESULT          (1u<<19)
 728
 729static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 730
 731static struct commit *interesting(struct commit_list *list)
 732{
 733        while (list) {
 734                struct commit *commit = list->item;
 735                list = list->next;
 736                if (commit->object.flags & STALE)
 737                        continue;
 738                return commit;
 739        }
 740        return NULL;
 741}
 742
 743/* all input commits in one and twos[] must have been parsed! */
 744static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 745{
 746        struct commit_list *list = NULL;
 747        struct commit_list *result = NULL;
 748        int i;
 749
 750        one->object.flags |= PARENT1;
 751        commit_list_insert_by_date(one, &list);
 752        if (!n)
 753                return list;
 754        for (i = 0; i < n; i++) {
 755                twos[i]->object.flags |= PARENT2;
 756                commit_list_insert_by_date(twos[i], &list);
 757        }
 758
 759        while (interesting(list)) {
 760                struct commit *commit;
 761                struct commit_list *parents;
 762                struct commit_list *next;
 763                int flags;
 764
 765                commit = list->item;
 766                next = list->next;
 767                free(list);
 768                list = next;
 769
 770                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 771                if (flags == (PARENT1 | PARENT2)) {
 772                        if (!(commit->object.flags & RESULT)) {
 773                                commit->object.flags |= RESULT;
 774                                commit_list_insert_by_date(commit, &result);
 775                        }
 776                        /* Mark parents of a found merge stale */
 777                        flags |= STALE;
 778                }
 779                parents = commit->parents;
 780                while (parents) {
 781                        struct commit *p = parents->item;
 782                        parents = parents->next;
 783                        if ((p->object.flags & flags) == flags)
 784                                continue;
 785                        if (parse_commit(p))
 786                                return NULL;
 787                        p->object.flags |= flags;
 788                        commit_list_insert_by_date(p, &list);
 789                }
 790        }
 791
 792        free_commit_list(list);
 793        return result;
 794}
 795
 796static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 797{
 798        struct commit_list *list = NULL;
 799        struct commit_list *result = NULL;
 800        int i;
 801
 802        for (i = 0; i < n; i++) {
 803                if (one == twos[i])
 804                        /*
 805                         * We do not mark this even with RESULT so we do not
 806                         * have to clean it up.
 807                         */
 808                        return commit_list_insert(one, &result);
 809        }
 810
 811        if (parse_commit(one))
 812                return NULL;
 813        for (i = 0; i < n; i++) {
 814                if (parse_commit(twos[i]))
 815                        return NULL;
 816        }
 817
 818        list = paint_down_to_common(one, n, twos);
 819
 820        while (list) {
 821                struct commit_list *next = list->next;
 822                if (!(list->item->object.flags & STALE))
 823                        commit_list_insert_by_date(list->item, &result);
 824                free(list);
 825                list = next;
 826        }
 827        return result;
 828}
 829
 830struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 831{
 832        struct commit_list *i, *j, *k, *ret = NULL;
 833
 834        if (!in)
 835                return ret;
 836
 837        commit_list_insert(in->item, &ret);
 838
 839        for (i = in->next; i; i = i->next) {
 840                struct commit_list *new = NULL, *end = NULL;
 841
 842                for (j = ret; j; j = j->next) {
 843                        struct commit_list *bases;
 844                        bases = get_merge_bases(i->item, j->item, 1);
 845                        if (!new)
 846                                new = bases;
 847                        else
 848                                end->next = bases;
 849                        for (k = bases; k; k = k->next)
 850                                end = k;
 851                }
 852                ret = new;
 853        }
 854        return ret;
 855}
 856
 857static int remove_redundant(struct commit **array, int cnt)
 858{
 859        /*
 860         * Some commit in the array may be an ancestor of
 861         * another commit.  Move such commit to the end of
 862         * the array, and return the number of commits that
 863         * are independent from each other.
 864         */
 865        struct commit **work;
 866        unsigned char *redundant;
 867        int *filled_index;
 868        int i, j, filled;
 869
 870        work = xcalloc(cnt, sizeof(*work));
 871        redundant = xcalloc(cnt, 1);
 872        filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 873
 874        for (i = 0; i < cnt; i++)
 875                parse_commit(array[i]);
 876        for (i = 0; i < cnt; i++) {
 877                struct commit_list *common;
 878
 879                if (redundant[i])
 880                        continue;
 881                for (j = filled = 0; j < cnt; j++) {
 882                        if (i == j || redundant[j])
 883                                continue;
 884                        filled_index[filled] = j;
 885                        work[filled++] = array[j];
 886                }
 887                common = paint_down_to_common(array[i], filled, work);
 888                if (array[i]->object.flags & PARENT2)
 889                        redundant[i] = 1;
 890                for (j = 0; j < filled; j++)
 891                        if (work[j]->object.flags & PARENT1)
 892                                redundant[filled_index[j]] = 1;
 893                clear_commit_marks(array[i], all_flags);
 894                for (j = 0; j < filled; j++)
 895                        clear_commit_marks(work[j], all_flags);
 896                free_commit_list(common);
 897        }
 898
 899        /* Now collect the result */
 900        memcpy(work, array, sizeof(*array) * cnt);
 901        for (i = filled = 0; i < cnt; i++)
 902                if (!redundant[i])
 903                        array[filled++] = work[i];
 904        for (j = filled, i = 0; i < cnt; i++)
 905                if (redundant[i])
 906                        array[j++] = work[i];
 907        free(work);
 908        free(redundant);
 909        free(filled_index);
 910        return filled;
 911}
 912
 913struct commit_list *get_merge_bases_many(struct commit *one,
 914                                         int n,
 915                                         struct commit **twos,
 916                                         int cleanup)
 917{
 918        struct commit_list *list;
 919        struct commit **rslt;
 920        struct commit_list *result;
 921        int cnt, i;
 922
 923        result = merge_bases_many(one, n, twos);
 924        for (i = 0; i < n; i++) {
 925                if (one == twos[i])
 926                        return result;
 927        }
 928        if (!result || !result->next) {
 929                if (cleanup) {
 930                        clear_commit_marks(one, all_flags);
 931                        clear_commit_marks_many(n, twos, all_flags);
 932                }
 933                return result;
 934        }
 935
 936        /* There are more than one */
 937        cnt = 0;
 938        list = result;
 939        while (list) {
 940                list = list->next;
 941                cnt++;
 942        }
 943        rslt = xcalloc(cnt, sizeof(*rslt));
 944        for (list = result, i = 0; list; list = list->next)
 945                rslt[i++] = list->item;
 946        free_commit_list(result);
 947
 948        clear_commit_marks(one, all_flags);
 949        clear_commit_marks_many(n, twos, all_flags);
 950
 951        cnt = remove_redundant(rslt, cnt);
 952        result = NULL;
 953        for (i = 0; i < cnt; i++)
 954                commit_list_insert_by_date(rslt[i], &result);
 955        free(rslt);
 956        return result;
 957}
 958
 959struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 960                                    int cleanup)
 961{
 962        return get_merge_bases_many(one, 1, &two, cleanup);
 963}
 964
 965/*
 966 * Is "commit" a descendant of one of the elements on the "with_commit" list?
 967 */
 968int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 969{
 970        if (!with_commit)
 971                return 1;
 972        while (with_commit) {
 973                struct commit *other;
 974
 975                other = with_commit->item;
 976                with_commit = with_commit->next;
 977                if (in_merge_bases(other, commit))
 978                        return 1;
 979        }
 980        return 0;
 981}
 982
 983/*
 984 * Is "commit" an ancestor of one of the "references"?
 985 */
 986int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 987{
 988        struct commit_list *bases;
 989        int ret = 0, i;
 990
 991        if (parse_commit(commit))
 992                return ret;
 993        for (i = 0; i < nr_reference; i++)
 994                if (parse_commit(reference[i]))
 995                        return ret;
 996
 997        bases = paint_down_to_common(commit, nr_reference, reference);
 998        if (commit->object.flags & PARENT2)
 999                ret = 1;
1000        clear_commit_marks(commit, all_flags);
1001        clear_commit_marks_many(nr_reference, reference, all_flags);
1002        free_commit_list(bases);
1003        return ret;
1004}
1005
1006/*
1007 * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
1008 */
1009int in_merge_bases(struct commit *commit, struct commit *reference)
1010{
1011        return in_merge_bases_many(commit, 1, &reference);
1012}
1013
1014struct commit_list *reduce_heads(struct commit_list *heads)
1015{
1016        struct commit_list *p;
1017        struct commit_list *result = NULL, **tail = &result;
1018        struct commit **array;
1019        int num_head, i;
1020
1021        if (!heads)
1022                return NULL;
1023
1024        /* Uniquify */
1025        for (p = heads; p; p = p->next)
1026                p->item->object.flags &= ~STALE;
1027        for (p = heads, num_head = 0; p; p = p->next) {
1028                if (p->item->object.flags & STALE)
1029                        continue;
1030                p->item->object.flags |= STALE;
1031                num_head++;
1032        }
1033        array = xcalloc(num_head, sizeof(*array));
1034        for (p = heads, i = 0; p; p = p->next) {
1035                if (p->item->object.flags & STALE) {
1036                        array[i++] = p->item;
1037                        p->item->object.flags &= ~STALE;
1038                }
1039        }
1040        num_head = remove_redundant(array, num_head);
1041        for (i = 0; i < num_head; i++)
1042                tail = &commit_list_insert(array[i], tail)->next;
1043        return result;
1044}
1045
1046static const char gpg_sig_header[] = "gpgsig";
1047static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1048
1049static int do_sign_commit(struct strbuf *buf, const char *keyid)
1050{
1051        struct strbuf sig = STRBUF_INIT;
1052        int inspos, copypos;
1053
1054        /* find the end of the header */
1055        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1056
1057        if (!keyid || !*keyid)
1058                keyid = get_signing_key();
1059        if (sign_buffer(buf, &sig, keyid)) {
1060                strbuf_release(&sig);
1061                return -1;
1062        }
1063
1064        for (copypos = 0; sig.buf[copypos]; ) {
1065                const char *bol = sig.buf + copypos;
1066                const char *eol = strchrnul(bol, '\n');
1067                int len = (eol - bol) + !!*eol;
1068
1069                if (!copypos) {
1070                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1071                        inspos += gpg_sig_header_len;
1072                }
1073                strbuf_insert(buf, inspos++, " ", 1);
1074                strbuf_insert(buf, inspos, bol, len);
1075                inspos += len;
1076                copypos += len;
1077        }
1078        strbuf_release(&sig);
1079        return 0;
1080}
1081
1082int parse_signed_commit(const unsigned char *sha1,
1083                        struct strbuf *payload, struct strbuf *signature)
1084{
1085        unsigned long size;
1086        enum object_type type;
1087        char *buffer = read_sha1_file(sha1, &type, &size);
1088        int in_signature, saw_signature = -1;
1089        char *line, *tail;
1090
1091        if (!buffer || type != OBJ_COMMIT)
1092                goto cleanup;
1093
1094        line = buffer;
1095        tail = buffer + size;
1096        in_signature = 0;
1097        saw_signature = 0;
1098        while (line < tail) {
1099                const char *sig = NULL;
1100                char *next = memchr(line, '\n', tail - line);
1101
1102                next = next ? next + 1 : tail;
1103                if (in_signature && line[0] == ' ')
1104                        sig = line + 1;
1105                else if (starts_with(line, gpg_sig_header) &&
1106                         line[gpg_sig_header_len] == ' ')
1107                        sig = line + gpg_sig_header_len + 1;
1108                if (sig) {
1109                        strbuf_add(signature, sig, next - sig);
1110                        saw_signature = 1;
1111                        in_signature = 1;
1112                } else {
1113                        if (*line == '\n')
1114                                /* dump the whole remainder of the buffer */
1115                                next = tail;
1116                        strbuf_add(payload, line, next - line);
1117                        in_signature = 0;
1118                }
1119                line = next;
1120        }
1121 cleanup:
1122        free(buffer);
1123        return saw_signature;
1124}
1125
1126static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1127{
1128        struct merge_remote_desc *desc;
1129        struct commit_extra_header *mergetag;
1130        char *buf;
1131        unsigned long size, len;
1132        enum object_type type;
1133
1134        desc = merge_remote_util(parent);
1135        if (!desc || !desc->obj)
1136                return;
1137        buf = read_sha1_file(desc->obj->sha1, &type, &size);
1138        if (!buf || type != OBJ_TAG)
1139                goto free_return;
1140        len = parse_signature(buf, size);
1141        if (size == len)
1142                goto free_return;
1143        /*
1144         * We could verify this signature and either omit the tag when
1145         * it does not validate, but the integrator may not have the
1146         * public key of the signer of the tag he is merging, while a
1147         * later auditor may have it while auditing, so let's not run
1148         * verify-signed-buffer here for now...
1149         *
1150         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1151         *      warn("warning: signed tag unverified.");
1152         */
1153        mergetag = xcalloc(1, sizeof(*mergetag));
1154        mergetag->key = xstrdup("mergetag");
1155        mergetag->value = buf;
1156        mergetag->len = size;
1157
1158        **tail = mergetag;
1159        *tail = &mergetag->next;
1160        return;
1161
1162free_return:
1163        free(buf);
1164}
1165
1166static struct {
1167        char result;
1168        const char *check;
1169} sigcheck_gpg_status[] = {
1170        { 'G', "\n[GNUPG:] GOODSIG " },
1171        { 'B', "\n[GNUPG:] BADSIG " },
1172        { 'U', "\n[GNUPG:] TRUST_NEVER" },
1173        { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1174};
1175
1176static void parse_gpg_output(struct signature_check *sigc)
1177{
1178        const char *buf = sigc->gpg_status;
1179        int i;
1180
1181        /* Iterate over all search strings */
1182        for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1183                const char *found, *next;
1184
1185                if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
1186                        found = strstr(buf, sigcheck_gpg_status[i].check);
1187                        if (!found)
1188                                continue;
1189                        found += strlen(sigcheck_gpg_status[i].check);
1190                }
1191                sigc->result = sigcheck_gpg_status[i].result;
1192                /* The trust messages are not followed by key/signer information */
1193                if (sigc->result != 'U') {
1194                        sigc->key = xmemdupz(found, 16);
1195                        found += 17;
1196                        next = strchrnul(found, '\n');
1197                        sigc->signer = xmemdupz(found, next - found);
1198                }
1199        }
1200}
1201
1202void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1203{
1204        struct strbuf payload = STRBUF_INIT;
1205        struct strbuf signature = STRBUF_INIT;
1206        struct strbuf gpg_output = STRBUF_INIT;
1207        struct strbuf gpg_status = STRBUF_INIT;
1208        int status;
1209
1210        sigc->result = 'N';
1211
1212        if (parse_signed_commit(commit->object.sha1,
1213                                &payload, &signature) <= 0)
1214                goto out;
1215        status = verify_signed_buffer(payload.buf, payload.len,
1216                                      signature.buf, signature.len,
1217                                      &gpg_output, &gpg_status);
1218        if (status && !gpg_output.len)
1219                goto out;
1220        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1221        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1222        parse_gpg_output(sigc);
1223
1224 out:
1225        strbuf_release(&gpg_status);
1226        strbuf_release(&gpg_output);
1227        strbuf_release(&payload);
1228        strbuf_release(&signature);
1229}
1230
1231
1232
1233void append_merge_tag_headers(struct commit_list *parents,
1234                              struct commit_extra_header ***tail)
1235{
1236        while (parents) {
1237                struct commit *parent = parents->item;
1238                handle_signed_tag(parent, tail);
1239                parents = parents->next;
1240        }
1241}
1242
1243static void add_extra_header(struct strbuf *buffer,
1244                             struct commit_extra_header *extra)
1245{
1246        strbuf_addstr(buffer, extra->key);
1247        if (extra->len)
1248                strbuf_add_lines(buffer, " ", extra->value, extra->len);
1249        else
1250                strbuf_addch(buffer, '\n');
1251}
1252
1253struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1254                                                      const char **exclude)
1255{
1256        struct commit_extra_header *extra = NULL;
1257        unsigned long size;
1258        enum object_type type;
1259        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1260        if (buffer && type == OBJ_COMMIT)
1261                extra = read_commit_extra_header_lines(buffer, size, exclude);
1262        free(buffer);
1263        return extra;
1264}
1265
1266static inline int standard_header_field(const char *field, size_t len)
1267{
1268        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1269                (len == 6 && !memcmp(field, "parent ", 7)) ||
1270                (len == 6 && !memcmp(field, "author ", 7)) ||
1271                (len == 9 && !memcmp(field, "committer ", 10)) ||
1272                (len == 8 && !memcmp(field, "encoding ", 9)));
1273}
1274
1275static int excluded_header_field(const char *field, size_t len, const char **exclude)
1276{
1277        if (!exclude)
1278                return 0;
1279
1280        while (*exclude) {
1281                size_t xlen = strlen(*exclude);
1282                if (len == xlen &&
1283                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1284                        return 1;
1285                exclude++;
1286        }
1287        return 0;
1288}
1289
1290static struct commit_extra_header *read_commit_extra_header_lines(
1291        const char *buffer, size_t size,
1292        const char **exclude)
1293{
1294        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1295        const char *line, *next, *eof, *eob;
1296        struct strbuf buf = STRBUF_INIT;
1297
1298        for (line = buffer, eob = line + size;
1299             line < eob && *line != '\n';
1300             line = next) {
1301                next = memchr(line, '\n', eob - line);
1302                next = next ? next + 1 : eob;
1303                if (*line == ' ') {
1304                        /* continuation */
1305                        if (it)
1306                                strbuf_add(&buf, line + 1, next - (line + 1));
1307                        continue;
1308                }
1309                if (it)
1310                        it->value = strbuf_detach(&buf, &it->len);
1311                strbuf_reset(&buf);
1312                it = NULL;
1313
1314                eof = strchr(line, ' ');
1315                if (next <= eof)
1316                        eof = next;
1317
1318                if (standard_header_field(line, eof - line) ||
1319                    excluded_header_field(line, eof - line, exclude))
1320                        continue;
1321
1322                it = xcalloc(1, sizeof(*it));
1323                it->key = xmemdupz(line, eof-line);
1324                *tail = it;
1325                tail = &it->next;
1326                if (eof + 1 < next)
1327                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1328        }
1329        if (it)
1330                it->value = strbuf_detach(&buf, &it->len);
1331        return extra;
1332}
1333
1334void free_commit_extra_headers(struct commit_extra_header *extra)
1335{
1336        while (extra) {
1337                struct commit_extra_header *next = extra->next;
1338                free(extra->key);
1339                free(extra->value);
1340                free(extra);
1341                extra = next;
1342        }
1343}
1344
1345int commit_tree(const struct strbuf *msg, const unsigned char *tree,
1346                struct commit_list *parents, unsigned char *ret,
1347                const char *author, const char *sign_commit)
1348{
1349        struct commit_extra_header *extra = NULL, **tail = &extra;
1350        int result;
1351
1352        append_merge_tag_headers(parents, &tail);
1353        result = commit_tree_extended(msg, tree, parents, ret,
1354                                      author, sign_commit, extra);
1355        free_commit_extra_headers(extra);
1356        return result;
1357}
1358
1359static int find_invalid_utf8(const char *buf, int len)
1360{
1361        int offset = 0;
1362        static const unsigned int max_codepoint[] = {
1363                0x7f, 0x7ff, 0xffff, 0x10ffff
1364        };
1365
1366        while (len) {
1367                unsigned char c = *buf++;
1368                int bytes, bad_offset;
1369                unsigned int codepoint;
1370                unsigned int min_val, max_val;
1371
1372                len--;
1373                offset++;
1374
1375                /* Simple US-ASCII? No worries. */
1376                if (c < 0x80)
1377                        continue;
1378
1379                bad_offset = offset-1;
1380
1381                /*
1382                 * Count how many more high bits set: that's how
1383                 * many more bytes this sequence should have.
1384                 */
1385                bytes = 0;
1386                while (c & 0x40) {
1387                        c <<= 1;
1388                        bytes++;
1389                }
1390
1391                /*
1392                 * Must be between 1 and 3 more bytes.  Longer sequences result in
1393                 * codepoints beyond U+10FFFF, which are guaranteed never to exist.
1394                 */
1395                if (bytes < 1 || 3 < bytes)
1396                        return bad_offset;
1397
1398                /* Do we *have* that many bytes? */
1399                if (len < bytes)
1400                        return bad_offset;
1401
1402                /*
1403                 * Place the encoded bits at the bottom of the value and compute the
1404                 * valid range.
1405                 */
1406                codepoint = (c & 0x7f) >> bytes;
1407                min_val = max_codepoint[bytes-1] + 1;
1408                max_val = max_codepoint[bytes];
1409
1410                offset += bytes;
1411                len -= bytes;
1412
1413                /* And verify that they are good continuation bytes */
1414                do {
1415                        codepoint <<= 6;
1416                        codepoint |= *buf & 0x3f;
1417                        if ((*buf++ & 0xc0) != 0x80)
1418                                return bad_offset;
1419                } while (--bytes);
1420
1421                /* Reject codepoints that are out of range for the sequence length. */
1422                if (codepoint < min_val || codepoint > max_val)
1423                        return bad_offset;
1424                /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
1425                if ((codepoint & 0x1ff800) == 0xd800)
1426                        return bad_offset;
1427                /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
1428                if ((codepoint & 0xfffe) == 0xfffe)
1429                        return bad_offset;
1430                /* So are anything in the range U+FDD0..U+FDEF. */
1431                if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
1432                        return bad_offset;
1433        }
1434        return -1;
1435}
1436
1437/*
1438 * This verifies that the buffer is in proper utf8 format.
1439 *
1440 * If it isn't, it assumes any non-utf8 characters are Latin1,
1441 * and does the conversion.
1442 */
1443static int verify_utf8(struct strbuf *buf)
1444{
1445        int ok = 1;
1446        long pos = 0;
1447
1448        for (;;) {
1449                int bad;
1450                unsigned char c;
1451                unsigned char replace[2];
1452
1453                bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1454                if (bad < 0)
1455                        return ok;
1456                pos += bad;
1457                ok = 0;
1458                c = buf->buf[pos];
1459                strbuf_remove(buf, pos, 1);
1460
1461                /* We know 'c' must be in the range 128-255 */
1462                replace[0] = 0xc0 + (c >> 6);
1463                replace[1] = 0x80 + (c & 0x3f);
1464                strbuf_insert(buf, pos, replace, 2);
1465                pos += 2;
1466        }
1467}
1468
1469static const char commit_utf8_warn[] =
1470"Warning: commit message did not conform to UTF-8.\n"
1471"You may want to amend it after fixing the message, or set the config\n"
1472"variable i18n.commitencoding to the encoding your project uses.\n";
1473
1474int commit_tree_extended(const struct strbuf *msg, const unsigned char *tree,
1475                         struct commit_list *parents, unsigned char *ret,
1476                         const char *author, const char *sign_commit,
1477                         struct commit_extra_header *extra)
1478{
1479        int result;
1480        int encoding_is_utf8;
1481        struct strbuf buffer;
1482
1483        assert_sha1_type(tree, OBJ_TREE);
1484
1485        if (memchr(msg->buf, '\0', msg->len))
1486                return error("a NUL byte in commit log message not allowed.");
1487
1488        /* Not having i18n.commitencoding is the same as having utf-8 */
1489        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1490
1491        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1492        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1493
1494        /*
1495         * NOTE! This ordering means that the same exact tree merged with a
1496         * different order of parents will be a _different_ changeset even
1497         * if everything else stays the same.
1498         */
1499        while (parents) {
1500                struct commit_list *next = parents->next;
1501                struct commit *parent = parents->item;
1502
1503                strbuf_addf(&buffer, "parent %s\n",
1504                            sha1_to_hex(parent->object.sha1));
1505                free(parents);
1506                parents = next;
1507        }
1508
1509        /* Person/date information */
1510        if (!author)
1511                author = git_author_info(IDENT_STRICT);
1512        strbuf_addf(&buffer, "author %s\n", author);
1513        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1514        if (!encoding_is_utf8)
1515                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1516
1517        while (extra) {
1518                add_extra_header(&buffer, extra);
1519                extra = extra->next;
1520        }
1521        strbuf_addch(&buffer, '\n');
1522
1523        /* And add the comment */
1524        strbuf_addbuf(&buffer, msg);
1525
1526        /* And check the encoding */
1527        if (encoding_is_utf8 && !verify_utf8(&buffer))
1528                fprintf(stderr, commit_utf8_warn);
1529
1530        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1531                return -1;
1532
1533        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1534        strbuf_release(&buffer);
1535        return result;
1536}
1537
1538struct commit *get_merge_parent(const char *name)
1539{
1540        struct object *obj;
1541        struct commit *commit;
1542        unsigned char sha1[20];
1543        if (get_sha1(name, sha1))
1544                return NULL;
1545        obj = parse_object(sha1);
1546        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1547        if (commit && !commit->util) {
1548                struct merge_remote_desc *desc;
1549                desc = xmalloc(sizeof(*desc));
1550                desc->obj = obj;
1551                desc->name = strdup(name);
1552                commit->util = desc;
1553        }
1554        return commit;
1555}
1556
1557/*
1558 * Append a commit to the end of the commit_list.
1559 *
1560 * next starts by pointing to the variable that holds the head of an
1561 * empty commit_list, and is updated to point to the "next" field of
1562 * the last item on the list as new commits are appended.
1563 *
1564 * Usage example:
1565 *
1566 *     struct commit_list *list;
1567 *     struct commit_list **next = &list;
1568 *
1569 *     next = commit_list_append(c1, next);
1570 *     next = commit_list_append(c2, next);
1571 *     assert(commit_list_count(list) == 2);
1572 *     return list;
1573 */
1574struct commit_list **commit_list_append(struct commit *commit,
1575                                        struct commit_list **next)
1576{
1577        struct commit_list *new = xmalloc(sizeof(struct commit_list));
1578        new->item = commit;
1579        *next = new;
1580        new->next = NULL;
1581        return &new->next;
1582}
1583
1584void print_commit_list(struct commit_list *list,
1585                       const char *format_cur,
1586                       const char *format_last)
1587{
1588        for ( ; list; list = list->next) {
1589                const char *format = list->next ? format_cur : format_last;
1590                printf(format, sha1_to_hex(list->item->object.sha1));
1591        }
1592}