Andrew's git / gitweb.git / commit.c
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commit.con commit t/README: justify why "! grep foo" is sufficient (53de742)
   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 (!commit || 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
 344int find_commit_subject(const char *commit_buffer, const char **subject)
 345{
 346        const char *eol;
 347        const char *p = commit_buffer;
 348
 349        while (*p && (*p != '\n' || p[1] != '\n'))
 350                p++;
 351        if (*p) {
 352                p += 2;
 353                for (eol = p; *eol && *eol != '\n'; eol++)
 354                        ; /* do nothing */
 355        } else
 356                eol = p;
 357
 358        *subject = p;
 359
 360        return eol - p;
 361}
 362
 363struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 364{
 365        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 366        new_list->item = item;
 367        new_list->next = *list_p;
 368        *list_p = new_list;
 369        return new_list;
 370}
 371
 372unsigned commit_list_count(const struct commit_list *l)
 373{
 374        unsigned c = 0;
 375        for (; l; l = l->next )
 376                c++;
 377        return c;
 378}
 379
 380struct commit_list *copy_commit_list(struct commit_list *list)
 381{
 382        struct commit_list *head = NULL;
 383        struct commit_list **pp = &head;
 384        while (list) {
 385                struct commit_list *new;
 386                new = xmalloc(sizeof(struct commit_list));
 387                new->item = list->item;
 388                new->next = NULL;
 389                *pp = new;
 390                pp = &new->next;
 391                list = list->next;
 392        }
 393        return head;
 394}
 395
 396void free_commit_list(struct commit_list *list)
 397{
 398        while (list) {
 399                struct commit_list *temp = list;
 400                list = temp->next;
 401                free(temp);
 402        }
 403}
 404
 405struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 406{
 407        struct commit_list **pp = list;
 408        struct commit_list *p;
 409        while ((p = *pp) != NULL) {
 410                if (p->item->date < item->date) {
 411                        break;
 412                }
 413                pp = &p->next;
 414        }
 415        return commit_list_insert(item, pp);
 416}
 417
 418static int commit_list_compare_by_date(const void *a, const void *b)
 419{
 420        unsigned long a_date = ((const struct commit_list *)a)->item->date;
 421        unsigned long b_date = ((const struct commit_list *)b)->item->date;
 422        if (a_date < b_date)
 423                return 1;
 424        if (a_date > b_date)
 425                return -1;
 426        return 0;
 427}
 428
 429static void *commit_list_get_next(const void *a)
 430{
 431        return ((const struct commit_list *)a)->next;
 432}
 433
 434static void commit_list_set_next(void *a, void *next)
 435{
 436        ((struct commit_list *)a)->next = next;
 437}
 438
 439void commit_list_sort_by_date(struct commit_list **list)
 440{
 441        *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 442                                commit_list_compare_by_date);
 443}
 444
 445struct commit *pop_most_recent_commit(struct commit_list **list,
 446                                      unsigned int mark)
 447{
 448        struct commit *ret = (*list)->item;
 449        struct commit_list *parents = ret->parents;
 450        struct commit_list *old = *list;
 451
 452        *list = (*list)->next;
 453        free(old);
 454
 455        while (parents) {
 456                struct commit *commit = parents->item;
 457                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 458                        commit->object.flags |= mark;
 459                        commit_list_insert_by_date(commit, list);
 460                }
 461                parents = parents->next;
 462        }
 463        return ret;
 464}
 465
 466static void clear_commit_marks_1(struct commit_list **plist,
 467                                 struct commit *commit, unsigned int mark)
 468{
 469        while (commit) {
 470                struct commit_list *parents;
 471
 472                if (!(mark & commit->object.flags))
 473                        return;
 474
 475                commit->object.flags &= ~mark;
 476
 477                parents = commit->parents;
 478                if (!parents)
 479                        return;
 480
 481                while ((parents = parents->next))
 482                        commit_list_insert(parents->item, plist);
 483
 484                commit = commit->parents->item;
 485        }
 486}
 487
 488void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 489{
 490        struct commit_list *list = NULL;
 491
 492        while (nr--) {
 493                commit_list_insert(*commit, &list);
 494                commit++;
 495        }
 496        while (list)
 497                clear_commit_marks_1(&list, pop_commit(&list), mark);
 498}
 499
 500void clear_commit_marks(struct commit *commit, unsigned int mark)
 501{
 502        clear_commit_marks_many(1, &commit, mark);
 503}
 504
 505void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 506{
 507        struct object *object;
 508        struct commit *commit;
 509        unsigned int i;
 510
 511        for (i = 0; i < a->nr; i++) {
 512                object = a->objects[i].item;
 513                commit = lookup_commit_reference_gently(object->sha1, 1);
 514                if (commit)
 515                        clear_commit_marks(commit, mark);
 516        }
 517}
 518
 519struct commit *pop_commit(struct commit_list **stack)
 520{
 521        struct commit_list *top = *stack;
 522        struct commit *item = top ? top->item : NULL;
 523
 524        if (top) {
 525                *stack = top->next;
 526                free(top);
 527        }
 528        return item;
 529}
 530
 531/*
 532 * Topological sort support
 533 */
 534
 535/* count number of children that have not been emitted */
 536define_commit_slab(indegree_slab, int);
 537
 538/* record author-date for each commit object */
 539define_commit_slab(author_date_slab, unsigned long);
 540
 541static void record_author_date(struct author_date_slab *author_date,
 542                               struct commit *commit)
 543{
 544        const char *buf, *line_end;
 545        char *buffer = NULL;
 546        struct ident_split ident;
 547        char *date_end;
 548        unsigned long date;
 549
 550        if (!commit->buffer) {
 551                unsigned long size;
 552                enum object_type type;
 553                buffer = read_sha1_file(commit->object.sha1, &type, &size);
 554                if (!buffer)
 555                        return;
 556        }
 557
 558        for (buf = commit->buffer ? commit->buffer : buffer;
 559             buf;
 560             buf = line_end + 1) {
 561                line_end = strchrnul(buf, '\n');
 562                if (prefixcmp(buf, "author ")) {
 563                        if (!line_end[0] || line_end[1] == '\n')
 564                                return; /* end of header */
 565                        continue;
 566                }
 567                if (split_ident_line(&ident,
 568                                     buf + strlen("author "),
 569                                     line_end - (buf + strlen("author "))) ||
 570                    !ident.date_begin || !ident.date_end)
 571                        goto fail_exit; /* malformed "author" line */
 572                break;
 573        }
 574
 575        date = strtoul(ident.date_begin, &date_end, 10);
 576        if (date_end != ident.date_end)
 577                goto fail_exit; /* malformed date */
 578        *(author_date_slab_at(author_date, commit)) = date;
 579
 580fail_exit:
 581        free(buffer);
 582}
 583
 584static int compare_commits_by_author_date(const void *a_, const void *b_,
 585                                          void *cb_data)
 586{
 587        const struct commit *a = a_, *b = b_;
 588        struct author_date_slab *author_date = cb_data;
 589        unsigned long a_date = *(author_date_slab_at(author_date, a));
 590        unsigned long b_date = *(author_date_slab_at(author_date, b));
 591
 592        /* newer commits with larger date first */
 593        if (a_date < b_date)
 594                return 1;
 595        else if (a_date > b_date)
 596                return -1;
 597        return 0;
 598}
 599
 600int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 601{
 602        const struct commit *a = a_, *b = b_;
 603        /* newer commits with larger date first */
 604        if (a->date < b->date)
 605                return 1;
 606        else if (a->date > b->date)
 607                return -1;
 608        return 0;
 609}
 610
 611/*
 612 * Performs an in-place topological sort on the list supplied.
 613 */
 614void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 615{
 616        struct commit_list *next, *orig = *list;
 617        struct commit_list **pptr;
 618        struct indegree_slab indegree;
 619        struct prio_queue queue;
 620        struct commit *commit;
 621        struct author_date_slab author_date;
 622
 623        if (!orig)
 624                return;
 625        *list = NULL;
 626
 627        init_indegree_slab(&indegree);
 628        memset(&queue, '\0', sizeof(queue));
 629
 630        switch (sort_order) {
 631        default: /* REV_SORT_IN_GRAPH_ORDER */
 632                queue.compare = NULL;
 633                break;
 634        case REV_SORT_BY_COMMIT_DATE:
 635                queue.compare = compare_commits_by_commit_date;
 636                break;
 637        case REV_SORT_BY_AUTHOR_DATE:
 638                init_author_date_slab(&author_date);
 639                queue.compare = compare_commits_by_author_date;
 640                queue.cb_data = &author_date;
 641                break;
 642        }
 643
 644        /* Mark them and clear the indegree */
 645        for (next = orig; next; next = next->next) {
 646                struct commit *commit = next->item;
 647                *(indegree_slab_at(&indegree, commit)) = 1;
 648                /* also record the author dates, if needed */
 649                if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 650                        record_author_date(&author_date, commit);
 651        }
 652
 653        /* update the indegree */
 654        for (next = orig; next; next = next->next) {
 655                struct commit_list *parents = next->item->parents;
 656                while (parents) {
 657                        struct commit *parent = parents->item;
 658                        int *pi = indegree_slab_at(&indegree, parent);
 659
 660                        if (*pi)
 661                                (*pi)++;
 662                        parents = parents->next;
 663                }
 664        }
 665
 666        /*
 667         * find the tips
 668         *
 669         * tips are nodes not reachable from any other node in the list
 670         *
 671         * the tips serve as a starting set for the work queue.
 672         */
 673        for (next = orig; next; next = next->next) {
 674                struct commit *commit = next->item;
 675
 676                if (*(indegree_slab_at(&indegree, commit)) == 1)
 677                        prio_queue_put(&queue, commit);
 678        }
 679
 680        /*
 681         * This is unfortunate; the initial tips need to be shown
 682         * in the order given from the revision traversal machinery.
 683         */
 684        if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 685                prio_queue_reverse(&queue);
 686
 687        /* We no longer need the commit list */
 688        free_commit_list(orig);
 689
 690        pptr = list;
 691        *list = NULL;
 692        while ((commit = prio_queue_get(&queue)) != NULL) {
 693                struct commit_list *parents;
 694
 695                for (parents = commit->parents; parents ; parents = parents->next) {
 696                        struct commit *parent = parents->item;
 697                        int *pi = indegree_slab_at(&indegree, parent);
 698
 699                        if (!*pi)
 700                                continue;
 701
 702                        /*
 703                         * parents are only enqueued for emission
 704                         * when all their children have been emitted thereby
 705                         * guaranteeing topological order.
 706                         */
 707                        if (--(*pi) == 1)
 708                                prio_queue_put(&queue, parent);
 709                }
 710                /*
 711                 * all children of commit have already been
 712                 * emitted. we can emit it now.
 713                 */
 714                *(indegree_slab_at(&indegree, commit)) = 0;
 715
 716                pptr = &commit_list_insert(commit, pptr)->next;
 717        }
 718
 719        clear_indegree_slab(&indegree);
 720        clear_prio_queue(&queue);
 721        if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 722                clear_author_date_slab(&author_date);
 723}
 724
 725/* merge-base stuff */
 726
 727/* bits #0..15 in revision.h */
 728#define PARENT1         (1u<<16)
 729#define PARENT2         (1u<<17)
 730#define STALE           (1u<<18)
 731#define RESULT          (1u<<19)
 732
 733static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 734
 735static struct commit *interesting(struct commit_list *list)
 736{
 737        while (list) {
 738                struct commit *commit = list->item;
 739                list = list->next;
 740                if (commit->object.flags & STALE)
 741                        continue;
 742                return commit;
 743        }
 744        return NULL;
 745}
 746
 747/* all input commits in one and twos[] must have been parsed! */
 748static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 749{
 750        struct commit_list *list = NULL;
 751        struct commit_list *result = NULL;
 752        int i;
 753
 754        one->object.flags |= PARENT1;
 755        commit_list_insert_by_date(one, &list);
 756        if (!n)
 757                return list;
 758        for (i = 0; i < n; i++) {
 759                twos[i]->object.flags |= PARENT2;
 760                commit_list_insert_by_date(twos[i], &list);
 761        }
 762
 763        while (interesting(list)) {
 764                struct commit *commit;
 765                struct commit_list *parents;
 766                struct commit_list *next;
 767                int flags;
 768
 769                commit = list->item;
 770                next = list->next;
 771                free(list);
 772                list = next;
 773
 774                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 775                if (flags == (PARENT1 | PARENT2)) {
 776                        if (!(commit->object.flags & RESULT)) {
 777                                commit->object.flags |= RESULT;
 778                                commit_list_insert_by_date(commit, &result);
 779                        }
 780                        /* Mark parents of a found merge stale */
 781                        flags |= STALE;
 782                }
 783                parents = commit->parents;
 784                while (parents) {
 785                        struct commit *p = parents->item;
 786                        parents = parents->next;
 787                        if ((p->object.flags & flags) == flags)
 788                                continue;
 789                        if (parse_commit(p))
 790                                return NULL;
 791                        p->object.flags |= flags;
 792                        commit_list_insert_by_date(p, &list);
 793                }
 794        }
 795
 796        free_commit_list(list);
 797        return result;
 798}
 799
 800static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 801{
 802        struct commit_list *list = NULL;
 803        struct commit_list *result = NULL;
 804        int i;
 805
 806        for (i = 0; i < n; i++) {
 807                if (one == twos[i])
 808                        /*
 809                         * We do not mark this even with RESULT so we do not
 810                         * have to clean it up.
 811                         */
 812                        return commit_list_insert(one, &result);
 813        }
 814
 815        if (parse_commit(one))
 816                return NULL;
 817        for (i = 0; i < n; i++) {
 818                if (parse_commit(twos[i]))
 819                        return NULL;
 820        }
 821
 822        list = paint_down_to_common(one, n, twos);
 823
 824        while (list) {
 825                struct commit_list *next = list->next;
 826                if (!(list->item->object.flags & STALE))
 827                        commit_list_insert_by_date(list->item, &result);
 828                free(list);
 829                list = next;
 830        }
 831        return result;
 832}
 833
 834struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 835{
 836        struct commit_list *i, *j, *k, *ret = NULL;
 837        struct commit_list **pptr = &ret;
 838
 839        for (i = in; i; i = i->next) {
 840                if (!ret)
 841                        pptr = &commit_list_insert(i->item, pptr)->next;
 842                else {
 843                        struct commit_list *new = NULL, *end = NULL;
 844
 845                        for (j = ret; j; j = j->next) {
 846                                struct commit_list *bases;
 847                                bases = get_merge_bases(i->item, j->item, 1);
 848                                if (!new)
 849                                        new = bases;
 850                                else
 851                                        end->next = bases;
 852                                for (k = bases; k; k = k->next)
 853                                        end = k;
 854                        }
 855                        ret = new;
 856                }
 857        }
 858        return ret;
 859}
 860
 861static int remove_redundant(struct commit **array, int cnt)
 862{
 863        /*
 864         * Some commit in the array may be an ancestor of
 865         * another commit.  Move such commit to the end of
 866         * the array, and return the number of commits that
 867         * are independent from each other.
 868         */
 869        struct commit **work;
 870        unsigned char *redundant;
 871        int *filled_index;
 872        int i, j, filled;
 873
 874        work = xcalloc(cnt, sizeof(*work));
 875        redundant = xcalloc(cnt, 1);
 876        filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 877
 878        for (i = 0; i < cnt; i++)
 879                parse_commit(array[i]);
 880        for (i = 0; i < cnt; i++) {
 881                struct commit_list *common;
 882
 883                if (redundant[i])
 884                        continue;
 885                for (j = filled = 0; j < cnt; j++) {
 886                        if (i == j || redundant[j])
 887                                continue;
 888                        filled_index[filled] = j;
 889                        work[filled++] = array[j];
 890                }
 891                common = paint_down_to_common(array[i], filled, work);
 892                if (array[i]->object.flags & PARENT2)
 893                        redundant[i] = 1;
 894                for (j = 0; j < filled; j++)
 895                        if (work[j]->object.flags & PARENT1)
 896                                redundant[filled_index[j]] = 1;
 897                clear_commit_marks(array[i], all_flags);
 898                for (j = 0; j < filled; j++)
 899                        clear_commit_marks(work[j], all_flags);
 900                free_commit_list(common);
 901        }
 902
 903        /* Now collect the result */
 904        memcpy(work, array, sizeof(*array) * cnt);
 905        for (i = filled = 0; i < cnt; i++)
 906                if (!redundant[i])
 907                        array[filled++] = work[i];
 908        for (j = filled, i = 0; i < cnt; i++)
 909                if (redundant[i])
 910                        array[j++] = work[i];
 911        free(work);
 912        free(redundant);
 913        free(filled_index);
 914        return filled;
 915}
 916
 917struct commit_list *get_merge_bases_many(struct commit *one,
 918                                         int n,
 919                                         struct commit **twos,
 920                                         int cleanup)
 921{
 922        struct commit_list *list;
 923        struct commit **rslt;
 924        struct commit_list *result;
 925        int cnt, i;
 926
 927        result = merge_bases_many(one, n, twos);
 928        for (i = 0; i < n; i++) {
 929                if (one == twos[i])
 930                        return result;
 931        }
 932        if (!result || !result->next) {
 933                if (cleanup) {
 934                        clear_commit_marks(one, all_flags);
 935                        clear_commit_marks_many(n, twos, all_flags);
 936                }
 937                return result;
 938        }
 939
 940        /* There are more than one */
 941        cnt = 0;
 942        list = result;
 943        while (list) {
 944                list = list->next;
 945                cnt++;
 946        }
 947        rslt = xcalloc(cnt, sizeof(*rslt));
 948        for (list = result, i = 0; list; list = list->next)
 949                rslt[i++] = list->item;
 950        free_commit_list(result);
 951
 952        clear_commit_marks(one, all_flags);
 953        clear_commit_marks_many(n, twos, all_flags);
 954
 955        cnt = remove_redundant(rslt, cnt);
 956        result = NULL;
 957        for (i = 0; i < cnt; i++)
 958                commit_list_insert_by_date(rslt[i], &result);
 959        free(rslt);
 960        return result;
 961}
 962
 963struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 964                                    int cleanup)
 965{
 966        return get_merge_bases_many(one, 1, &two, cleanup);
 967}
 968
 969/*
 970 * Is "commit" a descendant of one of the elements on the "with_commit" list?
 971 */
 972int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 973{
 974        if (!with_commit)
 975                return 1;
 976        while (with_commit) {
 977                struct commit *other;
 978
 979                other = with_commit->item;
 980                with_commit = with_commit->next;
 981                if (in_merge_bases(other, commit))
 982                        return 1;
 983        }
 984        return 0;
 985}
 986
 987/*
 988 * Is "commit" an ancestor of one of the "references"?
 989 */
 990int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 991{
 992        struct commit_list *bases;
 993        int ret = 0, i;
 994
 995        if (parse_commit(commit))
 996                return ret;
 997        for (i = 0; i < nr_reference; i++)
 998                if (parse_commit(reference[i]))
 999                        return ret;
1000
1001        bases = paint_down_to_common(commit, nr_reference, reference);
1002        if (commit->object.flags & PARENT2)
1003                ret = 1;
1004        clear_commit_marks(commit, all_flags);
1005        clear_commit_marks_many(nr_reference, reference, all_flags);
1006        free_commit_list(bases);
1007        return ret;
1008}
1009
1010/*
1011 * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
1012 */
1013int in_merge_bases(struct commit *commit, struct commit *reference)
1014{
1015        return in_merge_bases_many(commit, 1, &reference);
1016}
1017
1018struct commit_list *reduce_heads(struct commit_list *heads)
1019{
1020        struct commit_list *p;
1021        struct commit_list *result = NULL, **tail = &result;
1022        struct commit **array;
1023        int num_head, i;
1024
1025        if (!heads)
1026                return NULL;
1027
1028        /* Uniquify */
1029        for (p = heads; p; p = p->next)
1030                p->item->object.flags &= ~STALE;
1031        for (p = heads, num_head = 0; p; p = p->next) {
1032                if (p->item->object.flags & STALE)
1033                        continue;
1034                p->item->object.flags |= STALE;
1035                num_head++;
1036        }
1037        array = xcalloc(sizeof(*array), num_head);
1038        for (p = heads, i = 0; p; p = p->next) {
1039                if (p->item->object.flags & STALE) {
1040                        array[i++] = p->item;
1041                        p->item->object.flags &= ~STALE;
1042                }
1043        }
1044        num_head = remove_redundant(array, num_head);
1045        for (i = 0; i < num_head; i++)
1046                tail = &commit_list_insert(array[i], tail)->next;
1047        return result;
1048}
1049
1050static const char gpg_sig_header[] = "gpgsig";
1051static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1052
1053static int do_sign_commit(struct strbuf *buf, const char *keyid)
1054{
1055        struct strbuf sig = STRBUF_INIT;
1056        int inspos, copypos;
1057
1058        /* find the end of the header */
1059        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1060
1061        if (!keyid || !*keyid)
1062                keyid = get_signing_key();
1063        if (sign_buffer(buf, &sig, keyid)) {
1064                strbuf_release(&sig);
1065                return -1;
1066        }
1067
1068        for (copypos = 0; sig.buf[copypos]; ) {
1069                const char *bol = sig.buf + copypos;
1070                const char *eol = strchrnul(bol, '\n');
1071                int len = (eol - bol) + !!*eol;
1072
1073                if (!copypos) {
1074                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1075                        inspos += gpg_sig_header_len;
1076                }
1077                strbuf_insert(buf, inspos++, " ", 1);
1078                strbuf_insert(buf, inspos, bol, len);
1079                inspos += len;
1080                copypos += len;
1081        }
1082        strbuf_release(&sig);
1083        return 0;
1084}
1085
1086int parse_signed_commit(const unsigned char *sha1,
1087                        struct strbuf *payload, struct strbuf *signature)
1088{
1089        unsigned long size;
1090        enum object_type type;
1091        char *buffer = read_sha1_file(sha1, &type, &size);
1092        int in_signature, saw_signature = -1;
1093        char *line, *tail;
1094
1095        if (!buffer || type != OBJ_COMMIT)
1096                goto cleanup;
1097
1098        line = buffer;
1099        tail = buffer + size;
1100        in_signature = 0;
1101        saw_signature = 0;
1102        while (line < tail) {
1103                const char *sig = NULL;
1104                char *next = memchr(line, '\n', tail - line);
1105
1106                next = next ? next + 1 : tail;
1107                if (in_signature && line[0] == ' ')
1108                        sig = line + 1;
1109                else if (!prefixcmp(line, gpg_sig_header) &&
1110                         line[gpg_sig_header_len] == ' ')
1111                        sig = line + gpg_sig_header_len + 1;
1112                if (sig) {
1113                        strbuf_add(signature, sig, next - sig);
1114                        saw_signature = 1;
1115                        in_signature = 1;
1116                } else {
1117                        if (*line == '\n')
1118                                /* dump the whole remainder of the buffer */
1119                                next = tail;
1120                        strbuf_add(payload, line, next - line);
1121                        in_signature = 0;
1122                }
1123                line = next;
1124        }
1125 cleanup:
1126        free(buffer);
1127        return saw_signature;
1128}
1129
1130static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1131{
1132        struct merge_remote_desc *desc;
1133        struct commit_extra_header *mergetag;
1134        char *buf;
1135        unsigned long size, len;
1136        enum object_type type;
1137
1138        desc = merge_remote_util(parent);
1139        if (!desc || !desc->obj)
1140                return;
1141        buf = read_sha1_file(desc->obj->sha1, &type, &size);
1142        if (!buf || type != OBJ_TAG)
1143                goto free_return;
1144        len = parse_signature(buf, size);
1145        if (size == len)
1146                goto free_return;
1147        /*
1148         * We could verify this signature and either omit the tag when
1149         * it does not validate, but the integrator may not have the
1150         * public key of the signer of the tag he is merging, while a
1151         * later auditor may have it while auditing, so let's not run
1152         * verify-signed-buffer here for now...
1153         *
1154         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1155         *      warn("warning: signed tag unverified.");
1156         */
1157        mergetag = xcalloc(1, sizeof(*mergetag));
1158        mergetag->key = xstrdup("mergetag");
1159        mergetag->value = buf;
1160        mergetag->len = size;
1161
1162        **tail = mergetag;
1163        *tail = &mergetag->next;
1164        return;
1165
1166free_return:
1167        free(buf);
1168}
1169
1170static struct {
1171        char result;
1172        const char *check;
1173} sigcheck_gpg_status[] = {
1174        { 'G', "\n[GNUPG:] GOODSIG " },
1175        { 'B', "\n[GNUPG:] BADSIG " },
1176        { 'U', "\n[GNUPG:] TRUST_NEVER" },
1177        { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1178};
1179
1180static void parse_gpg_output(struct signature_check *sigc)
1181{
1182        const char *buf = sigc->gpg_status;
1183        int i;
1184
1185        /* Iterate over all search strings */
1186        for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1187                const char *found, *next;
1188
1189                if (!prefixcmp(buf, sigcheck_gpg_status[i].check + 1)) {
1190                        /* At the very beginning of the buffer */
1191                        found = buf + strlen(sigcheck_gpg_status[i].check + 1);
1192                } else {
1193                        found = strstr(buf, sigcheck_gpg_status[i].check);
1194                        if (!found)
1195                                continue;
1196                        found += strlen(sigcheck_gpg_status[i].check);
1197                }
1198                sigc->result = sigcheck_gpg_status[i].result;
1199                /* The trust messages are not followed by key/signer information */
1200                if (sigc->result != 'U') {
1201                        sigc->key = xmemdupz(found, 16);
1202                        found += 17;
1203                        next = strchrnul(found, '\n');
1204                        sigc->signer = xmemdupz(found, next - found);
1205                }
1206        }
1207}
1208
1209void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1210{
1211        struct strbuf payload = STRBUF_INIT;
1212        struct strbuf signature = STRBUF_INIT;
1213        struct strbuf gpg_output = STRBUF_INIT;
1214        struct strbuf gpg_status = STRBUF_INIT;
1215        int status;
1216
1217        sigc->result = 'N';
1218
1219        if (parse_signed_commit(commit->object.sha1,
1220                                &payload, &signature) <= 0)
1221                goto out;
1222        status = verify_signed_buffer(payload.buf, payload.len,
1223                                      signature.buf, signature.len,
1224                                      &gpg_output, &gpg_status);
1225        if (status && !gpg_output.len)
1226                goto out;
1227        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1228        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1229        parse_gpg_output(sigc);
1230
1231 out:
1232        strbuf_release(&gpg_status);
1233        strbuf_release(&gpg_output);
1234        strbuf_release(&payload);
1235        strbuf_release(&signature);
1236}
1237
1238
1239
1240void append_merge_tag_headers(struct commit_list *parents,
1241                              struct commit_extra_header ***tail)
1242{
1243        while (parents) {
1244                struct commit *parent = parents->item;
1245                handle_signed_tag(parent, tail);
1246                parents = parents->next;
1247        }
1248}
1249
1250static void add_extra_header(struct strbuf *buffer,
1251                             struct commit_extra_header *extra)
1252{
1253        strbuf_addstr(buffer, extra->key);
1254        if (extra->len)
1255                strbuf_add_lines(buffer, " ", extra->value, extra->len);
1256        else
1257                strbuf_addch(buffer, '\n');
1258}
1259
1260struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1261                                                      const char **exclude)
1262{
1263        struct commit_extra_header *extra = NULL;
1264        unsigned long size;
1265        enum object_type type;
1266        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1267        if (buffer && type == OBJ_COMMIT)
1268                extra = read_commit_extra_header_lines(buffer, size, exclude);
1269        free(buffer);
1270        return extra;
1271}
1272
1273static inline int standard_header_field(const char *field, size_t len)
1274{
1275        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1276                (len == 6 && !memcmp(field, "parent ", 7)) ||
1277                (len == 6 && !memcmp(field, "author ", 7)) ||
1278                (len == 9 && !memcmp(field, "committer ", 10)) ||
1279                (len == 8 && !memcmp(field, "encoding ", 9)));
1280}
1281
1282static int excluded_header_field(const char *field, size_t len, const char **exclude)
1283{
1284        if (!exclude)
1285                return 0;
1286
1287        while (*exclude) {
1288                size_t xlen = strlen(*exclude);
1289                if (len == xlen &&
1290                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1291                        return 1;
1292                exclude++;
1293        }
1294        return 0;
1295}
1296
1297static struct commit_extra_header *read_commit_extra_header_lines(
1298        const char *buffer, size_t size,
1299        const char **exclude)
1300{
1301        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1302        const char *line, *next, *eof, *eob;
1303        struct strbuf buf = STRBUF_INIT;
1304
1305        for (line = buffer, eob = line + size;
1306             line < eob && *line != '\n';
1307             line = next) {
1308                next = memchr(line, '\n', eob - line);
1309                next = next ? next + 1 : eob;
1310                if (*line == ' ') {
1311                        /* continuation */
1312                        if (it)
1313                                strbuf_add(&buf, line + 1, next - (line + 1));
1314                        continue;
1315                }
1316                if (it)
1317                        it->value = strbuf_detach(&buf, &it->len);
1318                strbuf_reset(&buf);
1319                it = NULL;
1320
1321                eof = strchr(line, ' ');
1322                if (next <= eof)
1323                        eof = next;
1324
1325                if (standard_header_field(line, eof - line) ||
1326                    excluded_header_field(line, eof - line, exclude))
1327                        continue;
1328
1329                it = xcalloc(1, sizeof(*it));
1330                it->key = xmemdupz(line, eof-line);
1331                *tail = it;
1332                tail = &it->next;
1333                if (eof + 1 < next)
1334                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1335        }
1336        if (it)
1337                it->value = strbuf_detach(&buf, &it->len);
1338        return extra;
1339}
1340
1341void free_commit_extra_headers(struct commit_extra_header *extra)
1342{
1343        while (extra) {
1344                struct commit_extra_header *next = extra->next;
1345                free(extra->key);
1346                free(extra->value);
1347                free(extra);
1348                extra = next;
1349        }
1350}
1351
1352int commit_tree(const struct strbuf *msg, unsigned char *tree,
1353                struct commit_list *parents, unsigned char *ret,
1354                const char *author, const char *sign_commit)
1355{
1356        struct commit_extra_header *extra = NULL, **tail = &extra;
1357        int result;
1358
1359        append_merge_tag_headers(parents, &tail);
1360        result = commit_tree_extended(msg, tree, parents, ret,
1361                                      author, sign_commit, extra);
1362        free_commit_extra_headers(extra);
1363        return result;
1364}
1365
1366static int find_invalid_utf8(const char *buf, int len)
1367{
1368        int offset = 0;
1369        static const unsigned int max_codepoint[] = {
1370                0x7f, 0x7ff, 0xffff, 0x10ffff
1371        };
1372
1373        while (len) {
1374                unsigned char c = *buf++;
1375                int bytes, bad_offset;
1376                unsigned int codepoint;
1377                unsigned int min_val, max_val;
1378
1379                len--;
1380                offset++;
1381
1382                /* Simple US-ASCII? No worries. */
1383                if (c < 0x80)
1384                        continue;
1385
1386                bad_offset = offset-1;
1387
1388                /*
1389                 * Count how many more high bits set: that's how
1390                 * many more bytes this sequence should have.
1391                 */
1392                bytes = 0;
1393                while (c & 0x40) {
1394                        c <<= 1;
1395                        bytes++;
1396                }
1397
1398                /*
1399                 * Must be between 1 and 3 more bytes.  Longer sequences result in
1400                 * codepoints beyond U+10FFFF, which are guaranteed never to exist.
1401                 */
1402                if (bytes < 1 || 3 < bytes)
1403                        return bad_offset;
1404
1405                /* Do we *have* that many bytes? */
1406                if (len < bytes)
1407                        return bad_offset;
1408
1409                /*
1410                 * Place the encoded bits at the bottom of the value and compute the
1411                 * valid range.
1412                 */
1413                codepoint = (c & 0x7f) >> bytes;
1414                min_val = max_codepoint[bytes-1] + 1;
1415                max_val = max_codepoint[bytes];
1416
1417                offset += bytes;
1418                len -= bytes;
1419
1420                /* And verify that they are good continuation bytes */
1421                do {
1422                        codepoint <<= 6;
1423                        codepoint |= *buf & 0x3f;
1424                        if ((*buf++ & 0xc0) != 0x80)
1425                                return bad_offset;
1426                } while (--bytes);
1427
1428                /* Reject codepoints that are out of range for the sequence length. */
1429                if (codepoint < min_val || codepoint > max_val)
1430                        return bad_offset;
1431                /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
1432                if ((codepoint & 0x1ff800) == 0xd800)
1433                        return bad_offset;
1434                /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
1435                if ((codepoint & 0xfffe) == 0xfffe)
1436                        return bad_offset;
1437                /* So are anything in the range U+FDD0..U+FDEF. */
1438                if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
1439                        return bad_offset;
1440        }
1441        return -1;
1442}
1443
1444/*
1445 * This verifies that the buffer is in proper utf8 format.
1446 *
1447 * If it isn't, it assumes any non-utf8 characters are Latin1,
1448 * and does the conversion.
1449 */
1450static int verify_utf8(struct strbuf *buf)
1451{
1452        int ok = 1;
1453        long pos = 0;
1454
1455        for (;;) {
1456                int bad;
1457                unsigned char c;
1458                unsigned char replace[2];
1459
1460                bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1461                if (bad < 0)
1462                        return ok;
1463                pos += bad;
1464                ok = 0;
1465                c = buf->buf[pos];
1466                strbuf_remove(buf, pos, 1);
1467
1468                /* We know 'c' must be in the range 128-255 */
1469                replace[0] = 0xc0 + (c >> 6);
1470                replace[1] = 0x80 + (c & 0x3f);
1471                strbuf_insert(buf, pos, replace, 2);
1472                pos += 2;
1473        }
1474}
1475
1476static const char commit_utf8_warn[] =
1477"Warning: commit message did not conform to UTF-8.\n"
1478"You may want to amend it after fixing the message, or set the config\n"
1479"variable i18n.commitencoding to the encoding your project uses.\n";
1480
1481int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1482                         struct commit_list *parents, unsigned char *ret,
1483                         const char *author, const char *sign_commit,
1484                         struct commit_extra_header *extra)
1485{
1486        int result;
1487        int encoding_is_utf8;
1488        struct strbuf buffer;
1489
1490        assert_sha1_type(tree, OBJ_TREE);
1491
1492        if (memchr(msg->buf, '\0', msg->len))
1493                return error("a NUL byte in commit log message not allowed.");
1494
1495        /* Not having i18n.commitencoding is the same as having utf-8 */
1496        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1497
1498        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1499        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1500
1501        /*
1502         * NOTE! This ordering means that the same exact tree merged with a
1503         * different order of parents will be a _different_ changeset even
1504         * if everything else stays the same.
1505         */
1506        while (parents) {
1507                struct commit_list *next = parents->next;
1508                struct commit *parent = parents->item;
1509
1510                strbuf_addf(&buffer, "parent %s\n",
1511                            sha1_to_hex(parent->object.sha1));
1512                free(parents);
1513                parents = next;
1514        }
1515
1516        /* Person/date information */
1517        if (!author)
1518                author = git_author_info(IDENT_STRICT);
1519        strbuf_addf(&buffer, "author %s\n", author);
1520        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1521        if (!encoding_is_utf8)
1522                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1523
1524        while (extra) {
1525                add_extra_header(&buffer, extra);
1526                extra = extra->next;
1527        }
1528        strbuf_addch(&buffer, '\n');
1529
1530        /* And add the comment */
1531        strbuf_addbuf(&buffer, msg);
1532
1533        /* And check the encoding */
1534        if (encoding_is_utf8 && !verify_utf8(&buffer))
1535                fprintf(stderr, commit_utf8_warn);
1536
1537        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1538                return -1;
1539
1540        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1541        strbuf_release(&buffer);
1542        return result;
1543}
1544
1545struct commit *get_merge_parent(const char *name)
1546{
1547        struct object *obj;
1548        struct commit *commit;
1549        unsigned char sha1[20];
1550        if (get_sha1(name, sha1))
1551                return NULL;
1552        obj = parse_object(sha1);
1553        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1554        if (commit && !commit->util) {
1555                struct merge_remote_desc *desc;
1556                desc = xmalloc(sizeof(*desc));
1557                desc->obj = obj;
1558                desc->name = strdup(name);
1559                commit->util = desc;
1560        }
1561        return commit;
1562}
1563
1564/*
1565 * Append a commit to the end of the commit_list.
1566 *
1567 * next starts by pointing to the variable that holds the head of an
1568 * empty commit_list, and is updated to point to the "next" field of
1569 * the last item on the list as new commits are appended.
1570 *
1571 * Usage example:
1572 *
1573 *     struct commit_list *list;
1574 *     struct commit_list **next = &list;
1575 *
1576 *     next = commit_list_append(c1, next);
1577 *     next = commit_list_append(c2, next);
1578 *     assert(commit_list_count(list) == 2);
1579 *     return list;
1580 */
1581struct commit_list **commit_list_append(struct commit *commit,
1582                                        struct commit_list **next)
1583{
1584        struct commit_list *new = xmalloc(sizeof(struct commit_list));
1585        new->item = commit;
1586        *next = new;
1587        new->next = NULL;
1588        return &new->next;
1589}
1590
1591void print_commit_list(struct commit_list *list,
1592                       const char *format_cur,
1593                       const char *format_last)
1594{
1595        for ( ; list; list = list->next) {
1596                const char *format = list->next ? format_cur : format_last;
1597                printf(format, sha1_to_hex(list->item->object.sha1));
1598        }
1599}