Andrew's git / gitweb.git / commit.c
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commit.con commit .mailmap: Combine more (email, name) to individual persons (f4f49e2)
   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        char buf[1024];
 200        if (!fp)
 201                return -1;
 202        while (fgets(buf, sizeof(buf), fp)) {
 203                /* The format is just "Commit Parent1 Parent2 ...\n" */
 204                int len = strlen(buf);
 205                struct commit_graft *graft = read_graft_line(buf, len);
 206                if (!graft)
 207                        continue;
 208                if (register_commit_graft(graft, 1))
 209                        error("duplicate graft data: %s", buf);
 210        }
 211        fclose(fp);
 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
 380void free_commit_list(struct commit_list *list)
 381{
 382        while (list) {
 383                struct commit_list *temp = list;
 384                list = temp->next;
 385                free(temp);
 386        }
 387}
 388
 389struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 390{
 391        struct commit_list **pp = list;
 392        struct commit_list *p;
 393        while ((p = *pp) != NULL) {
 394                if (p->item->date < item->date) {
 395                        break;
 396                }
 397                pp = &p->next;
 398        }
 399        return commit_list_insert(item, pp);
 400}
 401
 402static int commit_list_compare_by_date(const void *a, const void *b)
 403{
 404        unsigned long a_date = ((const struct commit_list *)a)->item->date;
 405        unsigned long b_date = ((const struct commit_list *)b)->item->date;
 406        if (a_date < b_date)
 407                return 1;
 408        if (a_date > b_date)
 409                return -1;
 410        return 0;
 411}
 412
 413static void *commit_list_get_next(const void *a)
 414{
 415        return ((const struct commit_list *)a)->next;
 416}
 417
 418static void commit_list_set_next(void *a, void *next)
 419{
 420        ((struct commit_list *)a)->next = next;
 421}
 422
 423void commit_list_sort_by_date(struct commit_list **list)
 424{
 425        *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 426                                commit_list_compare_by_date);
 427}
 428
 429struct commit *pop_most_recent_commit(struct commit_list **list,
 430                                      unsigned int mark)
 431{
 432        struct commit *ret = (*list)->item;
 433        struct commit_list *parents = ret->parents;
 434        struct commit_list *old = *list;
 435
 436        *list = (*list)->next;
 437        free(old);
 438
 439        while (parents) {
 440                struct commit *commit = parents->item;
 441                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 442                        commit->object.flags |= mark;
 443                        commit_list_insert_by_date(commit, list);
 444                }
 445                parents = parents->next;
 446        }
 447        return ret;
 448}
 449
 450static void clear_commit_marks_1(struct commit_list **plist,
 451                                 struct commit *commit, unsigned int mark)
 452{
 453        while (commit) {
 454                struct commit_list *parents;
 455
 456                if (!(mark & commit->object.flags))
 457                        return;
 458
 459                commit->object.flags &= ~mark;
 460
 461                parents = commit->parents;
 462                if (!parents)
 463                        return;
 464
 465                while ((parents = parents->next))
 466                        commit_list_insert(parents->item, plist);
 467
 468                commit = commit->parents->item;
 469        }
 470}
 471
 472void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 473{
 474        struct commit_list *list = NULL;
 475
 476        while (nr--) {
 477                commit_list_insert(*commit, &list);
 478                commit++;
 479        }
 480        while (list)
 481                clear_commit_marks_1(&list, pop_commit(&list), mark);
 482}
 483
 484void clear_commit_marks(struct commit *commit, unsigned int mark)
 485{
 486        clear_commit_marks_many(1, &commit, mark);
 487}
 488
 489void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 490{
 491        struct object *object;
 492        struct commit *commit;
 493        unsigned int i;
 494
 495        for (i = 0; i < a->nr; i++) {
 496                object = a->objects[i].item;
 497                commit = lookup_commit_reference_gently(object->sha1, 1);
 498                if (commit)
 499                        clear_commit_marks(commit, mark);
 500        }
 501}
 502
 503struct commit *pop_commit(struct commit_list **stack)
 504{
 505        struct commit_list *top = *stack;
 506        struct commit *item = top ? top->item : NULL;
 507
 508        if (top) {
 509                *stack = top->next;
 510                free(top);
 511        }
 512        return item;
 513}
 514
 515/*
 516 * Topological sort support
 517 */
 518
 519/* count number of children that have not been emitted */
 520define_commit_slab(indegree_slab, int);
 521
 522/* record author-date for each commit object */
 523define_commit_slab(author_date_slab, unsigned long);
 524
 525static void record_author_date(struct author_date_slab *author_date,
 526                               struct commit *commit)
 527{
 528        const char *buf, *line_end;
 529        char *buffer = NULL;
 530        struct ident_split ident;
 531        char *date_end;
 532        unsigned long date;
 533
 534        if (!commit->buffer) {
 535                unsigned long size;
 536                enum object_type type;
 537                buffer = read_sha1_file(commit->object.sha1, &type, &size);
 538                if (!buffer)
 539                        return;
 540        }
 541
 542        for (buf = commit->buffer ? commit->buffer : buffer;
 543             buf;
 544             buf = line_end + 1) {
 545                line_end = strchrnul(buf, '\n');
 546                if (prefixcmp(buf, "author ")) {
 547                        if (!line_end[0] || line_end[1] == '\n')
 548                                return; /* end of header */
 549                        continue;
 550                }
 551                if (split_ident_line(&ident,
 552                                     buf + strlen("author "),
 553                                     line_end - (buf + strlen("author "))) ||
 554                    !ident.date_begin || !ident.date_end)
 555                        goto fail_exit; /* malformed "author" line */
 556                break;
 557        }
 558
 559        date = strtoul(ident.date_begin, &date_end, 10);
 560        if (date_end != ident.date_end)
 561                goto fail_exit; /* malformed date */
 562        *(author_date_slab_at(author_date, commit)) = date;
 563
 564fail_exit:
 565        free(buffer);
 566}
 567
 568static int compare_commits_by_author_date(const void *a_, const void *b_,
 569                                          void *cb_data)
 570{
 571        const struct commit *a = a_, *b = b_;
 572        struct author_date_slab *author_date = cb_data;
 573        unsigned long a_date = *(author_date_slab_at(author_date, a));
 574        unsigned long b_date = *(author_date_slab_at(author_date, b));
 575
 576        /* newer commits with larger date first */
 577        if (a_date < b_date)
 578                return 1;
 579        else if (a_date > b_date)
 580                return -1;
 581        return 0;
 582}
 583
 584static int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
 585{
 586        const struct commit *a = a_, *b = b_;
 587        /* newer commits with larger date first */
 588        if (a->date < b->date)
 589                return 1;
 590        else if (a->date > b->date)
 591                return -1;
 592        return 0;
 593}
 594
 595/*
 596 * Performs an in-place topological sort on the list supplied.
 597 */
 598void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
 599{
 600        struct commit_list *next, *orig = *list;
 601        struct commit_list **pptr;
 602        struct indegree_slab indegree;
 603        struct prio_queue queue;
 604        struct commit *commit;
 605        struct author_date_slab author_date;
 606
 607        if (!orig)
 608                return;
 609        *list = NULL;
 610
 611        init_indegree_slab(&indegree);
 612        memset(&queue, '\0', sizeof(queue));
 613
 614        switch (sort_order) {
 615        default: /* REV_SORT_IN_GRAPH_ORDER */
 616                queue.compare = NULL;
 617                break;
 618        case REV_SORT_BY_COMMIT_DATE:
 619                queue.compare = compare_commits_by_commit_date;
 620                break;
 621        case REV_SORT_BY_AUTHOR_DATE:
 622                init_author_date_slab(&author_date);
 623                queue.compare = compare_commits_by_author_date;
 624                queue.cb_data = &author_date;
 625                break;
 626        }
 627
 628        /* Mark them and clear the indegree */
 629        for (next = orig; next; next = next->next) {
 630                struct commit *commit = next->item;
 631                *(indegree_slab_at(&indegree, commit)) = 1;
 632                /* also record the author dates, if needed */
 633                if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 634                        record_author_date(&author_date, commit);
 635        }
 636
 637        /* update the indegree */
 638        for (next = orig; next; next = next->next) {
 639                struct commit_list *parents = next->item->parents;
 640                while (parents) {
 641                        struct commit *parent = parents->item;
 642                        int *pi = indegree_slab_at(&indegree, parent);
 643
 644                        if (*pi)
 645                                (*pi)++;
 646                        parents = parents->next;
 647                }
 648        }
 649
 650        /*
 651         * find the tips
 652         *
 653         * tips are nodes not reachable from any other node in the list
 654         *
 655         * the tips serve as a starting set for the work queue.
 656         */
 657        for (next = orig; next; next = next->next) {
 658                struct commit *commit = next->item;
 659
 660                if (*(indegree_slab_at(&indegree, commit)) == 1)
 661                        prio_queue_put(&queue, commit);
 662        }
 663
 664        /*
 665         * This is unfortunate; the initial tips need to be shown
 666         * in the order given from the revision traversal machinery.
 667         */
 668        if (sort_order == REV_SORT_IN_GRAPH_ORDER)
 669                prio_queue_reverse(&queue);
 670
 671        /* We no longer need the commit list */
 672        free_commit_list(orig);
 673
 674        pptr = list;
 675        *list = NULL;
 676        while ((commit = prio_queue_get(&queue)) != NULL) {
 677                struct commit_list *parents;
 678
 679                for (parents = commit->parents; parents ; parents = parents->next) {
 680                        struct commit *parent = parents->item;
 681                        int *pi = indegree_slab_at(&indegree, parent);
 682
 683                        if (!*pi)
 684                                continue;
 685
 686                        /*
 687                         * parents are only enqueued for emission
 688                         * when all their children have been emitted thereby
 689                         * guaranteeing topological order.
 690                         */
 691                        if (--(*pi) == 1)
 692                                prio_queue_put(&queue, parent);
 693                }
 694                /*
 695                 * all children of commit have already been
 696                 * emitted. we can emit it now.
 697                 */
 698                *(indegree_slab_at(&indegree, commit)) = 0;
 699
 700                pptr = &commit_list_insert(commit, pptr)->next;
 701        }
 702
 703        clear_indegree_slab(&indegree);
 704        clear_prio_queue(&queue);
 705        if (sort_order == REV_SORT_BY_AUTHOR_DATE)
 706                clear_author_date_slab(&author_date);
 707}
 708
 709/* merge-base stuff */
 710
 711/* bits #0..15 in revision.h */
 712#define PARENT1         (1u<<16)
 713#define PARENT2         (1u<<17)
 714#define STALE           (1u<<18)
 715#define RESULT          (1u<<19)
 716
 717static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 718
 719static struct commit *interesting(struct commit_list *list)
 720{
 721        while (list) {
 722                struct commit *commit = list->item;
 723                list = list->next;
 724                if (commit->object.flags & STALE)
 725                        continue;
 726                return commit;
 727        }
 728        return NULL;
 729}
 730
 731/* all input commits in one and twos[] must have been parsed! */
 732static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 733{
 734        struct commit_list *list = NULL;
 735        struct commit_list *result = NULL;
 736        int i;
 737
 738        one->object.flags |= PARENT1;
 739        commit_list_insert_by_date(one, &list);
 740        if (!n)
 741                return list;
 742        for (i = 0; i < n; i++) {
 743                twos[i]->object.flags |= PARENT2;
 744                commit_list_insert_by_date(twos[i], &list);
 745        }
 746
 747        while (interesting(list)) {
 748                struct commit *commit;
 749                struct commit_list *parents;
 750                struct commit_list *next;
 751                int flags;
 752
 753                commit = list->item;
 754                next = list->next;
 755                free(list);
 756                list = next;
 757
 758                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 759                if (flags == (PARENT1 | PARENT2)) {
 760                        if (!(commit->object.flags & RESULT)) {
 761                                commit->object.flags |= RESULT;
 762                                commit_list_insert_by_date(commit, &result);
 763                        }
 764                        /* Mark parents of a found merge stale */
 765                        flags |= STALE;
 766                }
 767                parents = commit->parents;
 768                while (parents) {
 769                        struct commit *p = parents->item;
 770                        parents = parents->next;
 771                        if ((p->object.flags & flags) == flags)
 772                                continue;
 773                        if (parse_commit(p))
 774                                return NULL;
 775                        p->object.flags |= flags;
 776                        commit_list_insert_by_date(p, &list);
 777                }
 778        }
 779
 780        free_commit_list(list);
 781        return result;
 782}
 783
 784static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 785{
 786        struct commit_list *list = NULL;
 787        struct commit_list *result = NULL;
 788        int i;
 789
 790        for (i = 0; i < n; i++) {
 791                if (one == twos[i])
 792                        /*
 793                         * We do not mark this even with RESULT so we do not
 794                         * have to clean it up.
 795                         */
 796                        return commit_list_insert(one, &result);
 797        }
 798
 799        if (parse_commit(one))
 800                return NULL;
 801        for (i = 0; i < n; i++) {
 802                if (parse_commit(twos[i]))
 803                        return NULL;
 804        }
 805
 806        list = paint_down_to_common(one, n, twos);
 807
 808        while (list) {
 809                struct commit_list *next = list->next;
 810                if (!(list->item->object.flags & STALE))
 811                        commit_list_insert_by_date(list->item, &result);
 812                free(list);
 813                list = next;
 814        }
 815        return result;
 816}
 817
 818struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 819{
 820        struct commit_list *i, *j, *k, *ret = NULL;
 821        struct commit_list **pptr = &ret;
 822
 823        for (i = in; i; i = i->next) {
 824                if (!ret)
 825                        pptr = &commit_list_insert(i->item, pptr)->next;
 826                else {
 827                        struct commit_list *new = NULL, *end = NULL;
 828
 829                        for (j = ret; j; j = j->next) {
 830                                struct commit_list *bases;
 831                                bases = get_merge_bases(i->item, j->item, 1);
 832                                if (!new)
 833                                        new = bases;
 834                                else
 835                                        end->next = bases;
 836                                for (k = bases; k; k = k->next)
 837                                        end = k;
 838                        }
 839                        ret = new;
 840                }
 841        }
 842        return ret;
 843}
 844
 845static int remove_redundant(struct commit **array, int cnt)
 846{
 847        /*
 848         * Some commit in the array may be an ancestor of
 849         * another commit.  Move such commit to the end of
 850         * the array, and return the number of commits that
 851         * are independent from each other.
 852         */
 853        struct commit **work;
 854        unsigned char *redundant;
 855        int *filled_index;
 856        int i, j, filled;
 857
 858        work = xcalloc(cnt, sizeof(*work));
 859        redundant = xcalloc(cnt, 1);
 860        filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 861
 862        for (i = 0; i < cnt; i++)
 863                parse_commit(array[i]);
 864        for (i = 0; i < cnt; i++) {
 865                struct commit_list *common;
 866
 867                if (redundant[i])
 868                        continue;
 869                for (j = filled = 0; j < cnt; j++) {
 870                        if (i == j || redundant[j])
 871                                continue;
 872                        filled_index[filled] = j;
 873                        work[filled++] = array[j];
 874                }
 875                common = paint_down_to_common(array[i], filled, work);
 876                if (array[i]->object.flags & PARENT2)
 877                        redundant[i] = 1;
 878                for (j = 0; j < filled; j++)
 879                        if (work[j]->object.flags & PARENT1)
 880                                redundant[filled_index[j]] = 1;
 881                clear_commit_marks(array[i], all_flags);
 882                for (j = 0; j < filled; j++)
 883                        clear_commit_marks(work[j], all_flags);
 884                free_commit_list(common);
 885        }
 886
 887        /* Now collect the result */
 888        memcpy(work, array, sizeof(*array) * cnt);
 889        for (i = filled = 0; i < cnt; i++)
 890                if (!redundant[i])
 891                        array[filled++] = work[i];
 892        for (j = filled, i = 0; i < cnt; i++)
 893                if (redundant[i])
 894                        array[j++] = work[i];
 895        free(work);
 896        free(redundant);
 897        free(filled_index);
 898        return filled;
 899}
 900
 901struct commit_list *get_merge_bases_many(struct commit *one,
 902                                         int n,
 903                                         struct commit **twos,
 904                                         int cleanup)
 905{
 906        struct commit_list *list;
 907        struct commit **rslt;
 908        struct commit_list *result;
 909        int cnt, i;
 910
 911        result = merge_bases_many(one, n, twos);
 912        for (i = 0; i < n; i++) {
 913                if (one == twos[i])
 914                        return result;
 915        }
 916        if (!result || !result->next) {
 917                if (cleanup) {
 918                        clear_commit_marks(one, all_flags);
 919                        clear_commit_marks_many(n, twos, all_flags);
 920                }
 921                return result;
 922        }
 923
 924        /* There are more than one */
 925        cnt = 0;
 926        list = result;
 927        while (list) {
 928                list = list->next;
 929                cnt++;
 930        }
 931        rslt = xcalloc(cnt, sizeof(*rslt));
 932        for (list = result, i = 0; list; list = list->next)
 933                rslt[i++] = list->item;
 934        free_commit_list(result);
 935
 936        clear_commit_marks(one, all_flags);
 937        clear_commit_marks_many(n, twos, all_flags);
 938
 939        cnt = remove_redundant(rslt, cnt);
 940        result = NULL;
 941        for (i = 0; i < cnt; i++)
 942                commit_list_insert_by_date(rslt[i], &result);
 943        free(rslt);
 944        return result;
 945}
 946
 947struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 948                                    int cleanup)
 949{
 950        return get_merge_bases_many(one, 1, &two, cleanup);
 951}
 952
 953/*
 954 * Is "commit" a descendant of one of the elements on the "with_commit" list?
 955 */
 956int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 957{
 958        if (!with_commit)
 959                return 1;
 960        while (with_commit) {
 961                struct commit *other;
 962
 963                other = with_commit->item;
 964                with_commit = with_commit->next;
 965                if (in_merge_bases(other, commit))
 966                        return 1;
 967        }
 968        return 0;
 969}
 970
 971/*
 972 * Is "commit" an ancestor of one of the "references"?
 973 */
 974int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 975{
 976        struct commit_list *bases;
 977        int ret = 0, i;
 978
 979        if (parse_commit(commit))
 980                return ret;
 981        for (i = 0; i < nr_reference; i++)
 982                if (parse_commit(reference[i]))
 983                        return ret;
 984
 985        bases = paint_down_to_common(commit, nr_reference, reference);
 986        if (commit->object.flags & PARENT2)
 987                ret = 1;
 988        clear_commit_marks(commit, all_flags);
 989        clear_commit_marks_many(nr_reference, reference, all_flags);
 990        free_commit_list(bases);
 991        return ret;
 992}
 993
 994/*
 995 * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 996 */
 997int in_merge_bases(struct commit *commit, struct commit *reference)
 998{
 999        return in_merge_bases_many(commit, 1, &reference);
1000}
1001
1002struct commit_list *reduce_heads(struct commit_list *heads)
1003{
1004        struct commit_list *p;
1005        struct commit_list *result = NULL, **tail = &result;
1006        struct commit **array;
1007        int num_head, i;
1008
1009        if (!heads)
1010                return NULL;
1011
1012        /* Uniquify */
1013        for (p = heads; p; p = p->next)
1014                p->item->object.flags &= ~STALE;
1015        for (p = heads, num_head = 0; p; p = p->next) {
1016                if (p->item->object.flags & STALE)
1017                        continue;
1018                p->item->object.flags |= STALE;
1019                num_head++;
1020        }
1021        array = xcalloc(sizeof(*array), num_head);
1022        for (p = heads, i = 0; p; p = p->next) {
1023                if (p->item->object.flags & STALE) {
1024                        array[i++] = p->item;
1025                        p->item->object.flags &= ~STALE;
1026                }
1027        }
1028        num_head = remove_redundant(array, num_head);
1029        for (i = 0; i < num_head; i++)
1030                tail = &commit_list_insert(array[i], tail)->next;
1031        return result;
1032}
1033
1034static const char gpg_sig_header[] = "gpgsig";
1035static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
1036
1037static int do_sign_commit(struct strbuf *buf, const char *keyid)
1038{
1039        struct strbuf sig = STRBUF_INIT;
1040        int inspos, copypos;
1041
1042        /* find the end of the header */
1043        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
1044
1045        if (!keyid || !*keyid)
1046                keyid = get_signing_key();
1047        if (sign_buffer(buf, &sig, keyid)) {
1048                strbuf_release(&sig);
1049                return -1;
1050        }
1051
1052        for (copypos = 0; sig.buf[copypos]; ) {
1053                const char *bol = sig.buf + copypos;
1054                const char *eol = strchrnul(bol, '\n');
1055                int len = (eol - bol) + !!*eol;
1056
1057                if (!copypos) {
1058                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
1059                        inspos += gpg_sig_header_len;
1060                }
1061                strbuf_insert(buf, inspos++, " ", 1);
1062                strbuf_insert(buf, inspos, bol, len);
1063                inspos += len;
1064                copypos += len;
1065        }
1066        strbuf_release(&sig);
1067        return 0;
1068}
1069
1070int parse_signed_commit(const unsigned char *sha1,
1071                        struct strbuf *payload, struct strbuf *signature)
1072{
1073        unsigned long size;
1074        enum object_type type;
1075        char *buffer = read_sha1_file(sha1, &type, &size);
1076        int in_signature, saw_signature = -1;
1077        char *line, *tail;
1078
1079        if (!buffer || type != OBJ_COMMIT)
1080                goto cleanup;
1081
1082        line = buffer;
1083        tail = buffer + size;
1084        in_signature = 0;
1085        saw_signature = 0;
1086        while (line < tail) {
1087                const char *sig = NULL;
1088                char *next = memchr(line, '\n', tail - line);
1089
1090                next = next ? next + 1 : tail;
1091                if (in_signature && line[0] == ' ')
1092                        sig = line + 1;
1093                else if (!prefixcmp(line, gpg_sig_header) &&
1094                         line[gpg_sig_header_len] == ' ')
1095                        sig = line + gpg_sig_header_len + 1;
1096                if (sig) {
1097                        strbuf_add(signature, sig, next - sig);
1098                        saw_signature = 1;
1099                        in_signature = 1;
1100                } else {
1101                        if (*line == '\n')
1102                                /* dump the whole remainder of the buffer */
1103                                next = tail;
1104                        strbuf_add(payload, line, next - line);
1105                        in_signature = 0;
1106                }
1107                line = next;
1108        }
1109 cleanup:
1110        free(buffer);
1111        return saw_signature;
1112}
1113
1114static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
1115{
1116        struct merge_remote_desc *desc;
1117        struct commit_extra_header *mergetag;
1118        char *buf;
1119        unsigned long size, len;
1120        enum object_type type;
1121
1122        desc = merge_remote_util(parent);
1123        if (!desc || !desc->obj)
1124                return;
1125        buf = read_sha1_file(desc->obj->sha1, &type, &size);
1126        if (!buf || type != OBJ_TAG)
1127                goto free_return;
1128        len = parse_signature(buf, size);
1129        if (size == len)
1130                goto free_return;
1131        /*
1132         * We could verify this signature and either omit the tag when
1133         * it does not validate, but the integrator may not have the
1134         * public key of the signer of the tag he is merging, while a
1135         * later auditor may have it while auditing, so let's not run
1136         * verify-signed-buffer here for now...
1137         *
1138         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1139         *      warn("warning: signed tag unverified.");
1140         */
1141        mergetag = xcalloc(1, sizeof(*mergetag));
1142        mergetag->key = xstrdup("mergetag");
1143        mergetag->value = buf;
1144        mergetag->len = size;
1145
1146        **tail = mergetag;
1147        *tail = &mergetag->next;
1148        return;
1149
1150free_return:
1151        free(buf);
1152}
1153
1154static struct {
1155        char result;
1156        const char *check;
1157} sigcheck_gpg_status[] = {
1158        { 'G', "\n[GNUPG:] GOODSIG " },
1159        { 'B', "\n[GNUPG:] BADSIG " },
1160        { 'U', "\n[GNUPG:] TRUST_NEVER" },
1161        { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
1162};
1163
1164static void parse_gpg_output(struct signature_check *sigc)
1165{
1166        const char *buf = sigc->gpg_status;
1167        int i;
1168
1169        /* Iterate over all search strings */
1170        for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
1171                const char *found, *next;
1172
1173                if (!prefixcmp(buf, sigcheck_gpg_status[i].check + 1)) {
1174                        /* At the very beginning of the buffer */
1175                        found = buf + strlen(sigcheck_gpg_status[i].check + 1);
1176                } else {
1177                        found = strstr(buf, sigcheck_gpg_status[i].check);
1178                        if (!found)
1179                                continue;
1180                        found += strlen(sigcheck_gpg_status[i].check);
1181                }
1182                sigc->result = sigcheck_gpg_status[i].result;
1183                /* The trust messages are not followed by key/signer information */
1184                if (sigc->result != 'U') {
1185                        sigc->key = xmemdupz(found, 16);
1186                        found += 17;
1187                        next = strchrnul(found, '\n');
1188                        sigc->signer = xmemdupz(found, next - found);
1189                }
1190        }
1191}
1192
1193void check_commit_signature(const struct commit* commit, struct signature_check *sigc)
1194{
1195        struct strbuf payload = STRBUF_INIT;
1196        struct strbuf signature = STRBUF_INIT;
1197        struct strbuf gpg_output = STRBUF_INIT;
1198        struct strbuf gpg_status = STRBUF_INIT;
1199        int status;
1200
1201        sigc->result = 'N';
1202
1203        if (parse_signed_commit(commit->object.sha1,
1204                                &payload, &signature) <= 0)
1205                goto out;
1206        status = verify_signed_buffer(payload.buf, payload.len,
1207                                      signature.buf, signature.len,
1208                                      &gpg_output, &gpg_status);
1209        if (status && !gpg_output.len)
1210                goto out;
1211        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
1212        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
1213        parse_gpg_output(sigc);
1214
1215 out:
1216        strbuf_release(&gpg_status);
1217        strbuf_release(&gpg_output);
1218        strbuf_release(&payload);
1219        strbuf_release(&signature);
1220}
1221
1222
1223
1224void append_merge_tag_headers(struct commit_list *parents,
1225                              struct commit_extra_header ***tail)
1226{
1227        while (parents) {
1228                struct commit *parent = parents->item;
1229                handle_signed_tag(parent, tail);
1230                parents = parents->next;
1231        }
1232}
1233
1234static void add_extra_header(struct strbuf *buffer,
1235                             struct commit_extra_header *extra)
1236{
1237        strbuf_addstr(buffer, extra->key);
1238        if (extra->len)
1239                strbuf_add_lines(buffer, " ", extra->value, extra->len);
1240        else
1241                strbuf_addch(buffer, '\n');
1242}
1243
1244struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1245                                                      const char **exclude)
1246{
1247        struct commit_extra_header *extra = NULL;
1248        unsigned long size;
1249        enum object_type type;
1250        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1251        if (buffer && type == OBJ_COMMIT)
1252                extra = read_commit_extra_header_lines(buffer, size, exclude);
1253        free(buffer);
1254        return extra;
1255}
1256
1257static inline int standard_header_field(const char *field, size_t len)
1258{
1259        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1260                (len == 6 && !memcmp(field, "parent ", 7)) ||
1261                (len == 6 && !memcmp(field, "author ", 7)) ||
1262                (len == 9 && !memcmp(field, "committer ", 10)) ||
1263                (len == 8 && !memcmp(field, "encoding ", 9)));
1264}
1265
1266static int excluded_header_field(const char *field, size_t len, const char **exclude)
1267{
1268        if (!exclude)
1269                return 0;
1270
1271        while (*exclude) {
1272                size_t xlen = strlen(*exclude);
1273                if (len == xlen &&
1274                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1275                        return 1;
1276                exclude++;
1277        }
1278        return 0;
1279}
1280
1281static struct commit_extra_header *read_commit_extra_header_lines(
1282        const char *buffer, size_t size,
1283        const char **exclude)
1284{
1285        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1286        const char *line, *next, *eof, *eob;
1287        struct strbuf buf = STRBUF_INIT;
1288
1289        for (line = buffer, eob = line + size;
1290             line < eob && *line != '\n';
1291             line = next) {
1292                next = memchr(line, '\n', eob - line);
1293                next = next ? next + 1 : eob;
1294                if (*line == ' ') {
1295                        /* continuation */
1296                        if (it)
1297                                strbuf_add(&buf, line + 1, next - (line + 1));
1298                        continue;
1299                }
1300                if (it)
1301                        it->value = strbuf_detach(&buf, &it->len);
1302                strbuf_reset(&buf);
1303                it = NULL;
1304
1305                eof = strchr(line, ' ');
1306                if (next <= eof)
1307                        eof = next;
1308
1309                if (standard_header_field(line, eof - line) ||
1310                    excluded_header_field(line, eof - line, exclude))
1311                        continue;
1312
1313                it = xcalloc(1, sizeof(*it));
1314                it->key = xmemdupz(line, eof-line);
1315                *tail = it;
1316                tail = &it->next;
1317                if (eof + 1 < next)
1318                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1319        }
1320        if (it)
1321                it->value = strbuf_detach(&buf, &it->len);
1322        return extra;
1323}
1324
1325void free_commit_extra_headers(struct commit_extra_header *extra)
1326{
1327        while (extra) {
1328                struct commit_extra_header *next = extra->next;
1329                free(extra->key);
1330                free(extra->value);
1331                free(extra);
1332                extra = next;
1333        }
1334}
1335
1336int commit_tree(const struct strbuf *msg, unsigned char *tree,
1337                struct commit_list *parents, unsigned char *ret,
1338                const char *author, const char *sign_commit)
1339{
1340        struct commit_extra_header *extra = NULL, **tail = &extra;
1341        int result;
1342
1343        append_merge_tag_headers(parents, &tail);
1344        result = commit_tree_extended(msg, tree, parents, ret,
1345                                      author, sign_commit, extra);
1346        free_commit_extra_headers(extra);
1347        return result;
1348}
1349
1350static int find_invalid_utf8(const char *buf, int len)
1351{
1352        int offset = 0;
1353
1354        while (len) {
1355                unsigned char c = *buf++;
1356                int bytes, bad_offset;
1357
1358                len--;
1359                offset++;
1360
1361                /* Simple US-ASCII? No worries. */
1362                if (c < 0x80)
1363                        continue;
1364
1365                bad_offset = offset-1;
1366
1367                /*
1368                 * Count how many more high bits set: that's how
1369                 * many more bytes this sequence should have.
1370                 */
1371                bytes = 0;
1372                while (c & 0x40) {
1373                        c <<= 1;
1374                        bytes++;
1375                }
1376
1377                /* Must be between 1 and 5 more bytes */
1378                if (bytes < 1 || bytes > 5)
1379                        return bad_offset;
1380
1381                /* Do we *have* that many bytes? */
1382                if (len < bytes)
1383                        return bad_offset;
1384
1385                offset += bytes;
1386                len -= bytes;
1387
1388                /* And verify that they are good continuation bytes */
1389                do {
1390                        if ((*buf++ & 0xc0) != 0x80)
1391                                return bad_offset;
1392                } while (--bytes);
1393
1394                /* We could/should check the value and length here too */
1395        }
1396        return -1;
1397}
1398
1399/*
1400 * This verifies that the buffer is in proper utf8 format.
1401 *
1402 * If it isn't, it assumes any non-utf8 characters are Latin1,
1403 * and does the conversion.
1404 *
1405 * Fixme: we should probably also disallow overlong forms and
1406 * invalid characters. But we don't do that currently.
1407 */
1408static int verify_utf8(struct strbuf *buf)
1409{
1410        int ok = 1;
1411        long pos = 0;
1412
1413        for (;;) {
1414                int bad;
1415                unsigned char c;
1416                unsigned char replace[2];
1417
1418                bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1419                if (bad < 0)
1420                        return ok;
1421                pos += bad;
1422                ok = 0;
1423                c = buf->buf[pos];
1424                strbuf_remove(buf, pos, 1);
1425
1426                /* We know 'c' must be in the range 128-255 */
1427                replace[0] = 0xc0 + (c >> 6);
1428                replace[1] = 0x80 + (c & 0x3f);
1429                strbuf_insert(buf, pos, replace, 2);
1430                pos += 2;
1431        }
1432}
1433
1434static const char commit_utf8_warn[] =
1435"Warning: commit message did not conform to UTF-8.\n"
1436"You may want to amend it after fixing the message, or set the config\n"
1437"variable i18n.commitencoding to the encoding your project uses.\n";
1438
1439int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1440                         struct commit_list *parents, unsigned char *ret,
1441                         const char *author, const char *sign_commit,
1442                         struct commit_extra_header *extra)
1443{
1444        int result;
1445        int encoding_is_utf8;
1446        struct strbuf buffer;
1447
1448        assert_sha1_type(tree, OBJ_TREE);
1449
1450        if (memchr(msg->buf, '\0', msg->len))
1451                return error("a NUL byte in commit log message not allowed.");
1452
1453        /* Not having i18n.commitencoding is the same as having utf-8 */
1454        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1455
1456        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1457        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1458
1459        /*
1460         * NOTE! This ordering means that the same exact tree merged with a
1461         * different order of parents will be a _different_ changeset even
1462         * if everything else stays the same.
1463         */
1464        while (parents) {
1465                struct commit_list *next = parents->next;
1466                struct commit *parent = parents->item;
1467
1468                strbuf_addf(&buffer, "parent %s\n",
1469                            sha1_to_hex(parent->object.sha1));
1470                free(parents);
1471                parents = next;
1472        }
1473
1474        /* Person/date information */
1475        if (!author)
1476                author = git_author_info(IDENT_STRICT);
1477        strbuf_addf(&buffer, "author %s\n", author);
1478        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1479        if (!encoding_is_utf8)
1480                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1481
1482        while (extra) {
1483                add_extra_header(&buffer, extra);
1484                extra = extra->next;
1485        }
1486        strbuf_addch(&buffer, '\n');
1487
1488        /* And add the comment */
1489        strbuf_addbuf(&buffer, msg);
1490
1491        /* And check the encoding */
1492        if (encoding_is_utf8 && !verify_utf8(&buffer))
1493                fprintf(stderr, commit_utf8_warn);
1494
1495        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1496                return -1;
1497
1498        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1499        strbuf_release(&buffer);
1500        return result;
1501}
1502
1503struct commit *get_merge_parent(const char *name)
1504{
1505        struct object *obj;
1506        struct commit *commit;
1507        unsigned char sha1[20];
1508        if (get_sha1(name, sha1))
1509                return NULL;
1510        obj = parse_object(sha1);
1511        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1512        if (commit && !commit->util) {
1513                struct merge_remote_desc *desc;
1514                desc = xmalloc(sizeof(*desc));
1515                desc->obj = obj;
1516                desc->name = strdup(name);
1517                commit->util = desc;
1518        }
1519        return commit;
1520}
1521
1522/*
1523 * Append a commit to the end of the commit_list.
1524 *
1525 * next starts by pointing to the variable that holds the head of an
1526 * empty commit_list, and is updated to point to the "next" field of
1527 * the last item on the list as new commits are appended.
1528 *
1529 * Usage example:
1530 *
1531 *     struct commit_list *list;
1532 *     struct commit_list **next = &list;
1533 *
1534 *     next = commit_list_append(c1, next);
1535 *     next = commit_list_append(c2, next);
1536 *     assert(commit_list_count(list) == 2);
1537 *     return list;
1538 */
1539struct commit_list **commit_list_append(struct commit *commit,
1540                                        struct commit_list **next)
1541{
1542        struct commit_list *new = xmalloc(sizeof(struct commit_list));
1543        new->item = commit;
1544        *next = new;
1545        new->next = NULL;
1546        return &new->next;
1547}
1548
1549void print_commit_list(struct commit_list *list,
1550                       const char *format_cur,
1551                       const char *format_last)
1552{
1553        for ( ; list; list = list->next) {
1554                const char *format = list->next ? format_cur : format_last;
1555                printf(format, sha1_to_hex(list->item->object.sha1));
1556        }
1557}