Andrew's git / gitweb.git / commit.c
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commit.con commit commit.c: mark a file-scope private symbol as static (82a7529)
   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
  12static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  13
  14int save_commit_buffer = 1;
  15
  16const char *commit_type = "commit";
  17
  18static struct commit *check_commit(struct object *obj,
  19                                   const unsigned char *sha1,
  20                                   int quiet)
  21{
  22        if (obj->type != OBJ_COMMIT) {
  23                if (!quiet)
  24                        error("Object %s is a %s, not a commit",
  25                              sha1_to_hex(sha1), typename(obj->type));
  26                return NULL;
  27        }
  28        return (struct commit *) obj;
  29}
  30
  31struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  32                                              int quiet)
  33{
  34        struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  35
  36        if (!obj)
  37                return NULL;
  38        return check_commit(obj, sha1, quiet);
  39}
  40
  41struct commit *lookup_commit_reference(const unsigned char *sha1)
  42{
  43        return lookup_commit_reference_gently(sha1, 0);
  44}
  45
  46struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  47{
  48        struct commit *c = lookup_commit_reference(sha1);
  49        if (!c)
  50                die(_("could not parse %s"), ref_name);
  51        if (hashcmp(sha1, c->object.sha1)) {
  52                warning(_("%s %s is not a commit!"),
  53                        ref_name, sha1_to_hex(sha1));
  54        }
  55        return c;
  56}
  57
  58struct commit *lookup_commit(const unsigned char *sha1)
  59{
  60        struct object *obj = lookup_object(sha1);
  61        if (!obj)
  62                return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  63        if (!obj->type)
  64                obj->type = OBJ_COMMIT;
  65        return check_commit(obj, sha1, 0);
  66}
  67
  68struct commit *lookup_commit_reference_by_name(const char *name)
  69{
  70        unsigned char sha1[20];
  71        struct commit *commit;
  72
  73        if (get_sha1_committish(name, sha1))
  74                return NULL;
  75        commit = lookup_commit_reference(sha1);
  76        if (!commit || parse_commit(commit))
  77                return NULL;
  78        return commit;
  79}
  80
  81static unsigned long parse_commit_date(const char *buf, const char *tail)
  82{
  83        const char *dateptr;
  84
  85        if (buf + 6 >= tail)
  86                return 0;
  87        if (memcmp(buf, "author", 6))
  88                return 0;
  89        while (buf < tail && *buf++ != '\n')
  90                /* nada */;
  91        if (buf + 9 >= tail)
  92                return 0;
  93        if (memcmp(buf, "committer", 9))
  94                return 0;
  95        while (buf < tail && *buf++ != '>')
  96                /* nada */;
  97        if (buf >= tail)
  98                return 0;
  99        dateptr = buf;
 100        while (buf < tail && *buf++ != '\n')
 101                /* nada */;
 102        if (buf >= tail)
 103                return 0;
 104        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 105        return strtoul(dateptr, NULL, 10);
 106}
 107
 108static struct commit_graft **commit_graft;
 109static int commit_graft_alloc, commit_graft_nr;
 110
 111static int commit_graft_pos(const unsigned char *sha1)
 112{
 113        int lo, hi;
 114        lo = 0;
 115        hi = commit_graft_nr;
 116        while (lo < hi) {
 117                int mi = (lo + hi) / 2;
 118                struct commit_graft *graft = commit_graft[mi];
 119                int cmp = hashcmp(sha1, graft->sha1);
 120                if (!cmp)
 121                        return mi;
 122                if (cmp < 0)
 123                        hi = mi;
 124                else
 125                        lo = mi + 1;
 126        }
 127        return -lo - 1;
 128}
 129
 130int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 131{
 132        int pos = commit_graft_pos(graft->sha1);
 133
 134        if (0 <= pos) {
 135                if (ignore_dups)
 136                        free(graft);
 137                else {
 138                        free(commit_graft[pos]);
 139                        commit_graft[pos] = graft;
 140                }
 141                return 1;
 142        }
 143        pos = -pos - 1;
 144        if (commit_graft_alloc <= ++commit_graft_nr) {
 145                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 146                commit_graft = xrealloc(commit_graft,
 147                                        sizeof(*commit_graft) *
 148                                        commit_graft_alloc);
 149        }
 150        if (pos < commit_graft_nr)
 151                memmove(commit_graft + pos + 1,
 152                        commit_graft + pos,
 153                        (commit_graft_nr - pos - 1) *
 154                        sizeof(*commit_graft));
 155        commit_graft[pos] = graft;
 156        return 0;
 157}
 158
 159struct commit_graft *read_graft_line(char *buf, int len)
 160{
 161        /* The format is just "Commit Parent1 Parent2 ...\n" */
 162        int i;
 163        struct commit_graft *graft = NULL;
 164
 165        while (len && isspace(buf[len-1]))
 166                buf[--len] = '\0';
 167        if (buf[0] == '#' || buf[0] == '\0')
 168                return NULL;
 169        if ((len + 1) % 41)
 170                goto bad_graft_data;
 171        i = (len + 1) / 41 - 1;
 172        graft = xmalloc(sizeof(*graft) + 20 * i);
 173        graft->nr_parent = i;
 174        if (get_sha1_hex(buf, graft->sha1))
 175                goto bad_graft_data;
 176        for (i = 40; i < len; i += 41) {
 177                if (buf[i] != ' ')
 178                        goto bad_graft_data;
 179                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 180                        goto bad_graft_data;
 181        }
 182        return graft;
 183
 184bad_graft_data:
 185        error("bad graft data: %s", buf);
 186        free(graft);
 187        return NULL;
 188}
 189
 190static int read_graft_file(const char *graft_file)
 191{
 192        FILE *fp = fopen(graft_file, "r");
 193        char buf[1024];
 194        if (!fp)
 195                return -1;
 196        while (fgets(buf, sizeof(buf), fp)) {
 197                /* The format is just "Commit Parent1 Parent2 ...\n" */
 198                int len = strlen(buf);
 199                struct commit_graft *graft = read_graft_line(buf, len);
 200                if (!graft)
 201                        continue;
 202                if (register_commit_graft(graft, 1))
 203                        error("duplicate graft data: %s", buf);
 204        }
 205        fclose(fp);
 206        return 0;
 207}
 208
 209static void prepare_commit_graft(void)
 210{
 211        static int commit_graft_prepared;
 212        char *graft_file;
 213
 214        if (commit_graft_prepared)
 215                return;
 216        graft_file = get_graft_file();
 217        read_graft_file(graft_file);
 218        /* make sure shallows are read */
 219        is_repository_shallow();
 220        commit_graft_prepared = 1;
 221}
 222
 223struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 224{
 225        int pos;
 226        prepare_commit_graft();
 227        pos = commit_graft_pos(sha1);
 228        if (pos < 0)
 229                return NULL;
 230        return commit_graft[pos];
 231}
 232
 233int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 234{
 235        int i, ret;
 236        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 237                ret = fn(commit_graft[i], cb_data);
 238        return ret;
 239}
 240
 241int unregister_shallow(const unsigned char *sha1)
 242{
 243        int pos = commit_graft_pos(sha1);
 244        if (pos < 0)
 245                return -1;
 246        if (pos + 1 < commit_graft_nr)
 247                memmove(commit_graft + pos, commit_graft + pos + 1,
 248                                sizeof(struct commit_graft *)
 249                                * (commit_graft_nr - pos - 1));
 250        commit_graft_nr--;
 251        return 0;
 252}
 253
 254int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 255{
 256        const char *tail = buffer;
 257        const char *bufptr = buffer;
 258        unsigned char parent[20];
 259        struct commit_list **pptr;
 260        struct commit_graft *graft;
 261
 262        if (item->object.parsed)
 263                return 0;
 264        item->object.parsed = 1;
 265        tail += size;
 266        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 267                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 268        if (get_sha1_hex(bufptr + 5, parent) < 0)
 269                return error("bad tree pointer in commit %s",
 270                             sha1_to_hex(item->object.sha1));
 271        item->tree = lookup_tree(parent);
 272        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 273        pptr = &item->parents;
 274
 275        graft = lookup_commit_graft(item->object.sha1);
 276        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 277                struct commit *new_parent;
 278
 279                if (tail <= bufptr + 48 ||
 280                    get_sha1_hex(bufptr + 7, parent) ||
 281                    bufptr[47] != '\n')
 282                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 283                bufptr += 48;
 284                /*
 285                 * The clone is shallow if nr_parent < 0, and we must
 286                 * not traverse its real parents even when we unhide them.
 287                 */
 288                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 289                        continue;
 290                new_parent = lookup_commit(parent);
 291                if (new_parent)
 292                        pptr = &commit_list_insert(new_parent, pptr)->next;
 293        }
 294        if (graft) {
 295                int i;
 296                struct commit *new_parent;
 297                for (i = 0; i < graft->nr_parent; i++) {
 298                        new_parent = lookup_commit(graft->parent[i]);
 299                        if (!new_parent)
 300                                continue;
 301                        pptr = &commit_list_insert(new_parent, pptr)->next;
 302                }
 303        }
 304        item->date = parse_commit_date(bufptr, tail);
 305
 306        return 0;
 307}
 308
 309int parse_commit(struct commit *item)
 310{
 311        enum object_type type;
 312        void *buffer;
 313        unsigned long size;
 314        int ret;
 315
 316        if (!item)
 317                return -1;
 318        if (item->object.parsed)
 319                return 0;
 320        buffer = read_sha1_file(item->object.sha1, &type, &size);
 321        if (!buffer)
 322                return error("Could not read %s",
 323                             sha1_to_hex(item->object.sha1));
 324        if (type != OBJ_COMMIT) {
 325                free(buffer);
 326                return error("Object %s not a commit",
 327                             sha1_to_hex(item->object.sha1));
 328        }
 329        ret = parse_commit_buffer(item, buffer, size);
 330        if (save_commit_buffer && !ret) {
 331                item->buffer = buffer;
 332                return 0;
 333        }
 334        free(buffer);
 335        return ret;
 336}
 337
 338int find_commit_subject(const char *commit_buffer, const char **subject)
 339{
 340        const char *eol;
 341        const char *p = commit_buffer;
 342
 343        while (*p && (*p != '\n' || p[1] != '\n'))
 344                p++;
 345        if (*p) {
 346                p += 2;
 347                for (eol = p; *eol && *eol != '\n'; eol++)
 348                        ; /* do nothing */
 349        } else
 350                eol = p;
 351
 352        *subject = p;
 353
 354        return eol - p;
 355}
 356
 357struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 358{
 359        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 360        new_list->item = item;
 361        new_list->next = *list_p;
 362        *list_p = new_list;
 363        return new_list;
 364}
 365
 366unsigned commit_list_count(const struct commit_list *l)
 367{
 368        unsigned c = 0;
 369        for (; l; l = l->next )
 370                c++;
 371        return c;
 372}
 373
 374void free_commit_list(struct commit_list *list)
 375{
 376        while (list) {
 377                struct commit_list *temp = list;
 378                list = temp->next;
 379                free(temp);
 380        }
 381}
 382
 383struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 384{
 385        struct commit_list **pp = list;
 386        struct commit_list *p;
 387        while ((p = *pp) != NULL) {
 388                if (p->item->date < item->date) {
 389                        break;
 390                }
 391                pp = &p->next;
 392        }
 393        return commit_list_insert(item, pp);
 394}
 395
 396static int commit_list_compare_by_date(const void *a, const void *b)
 397{
 398        unsigned long a_date = ((const struct commit_list *)a)->item->date;
 399        unsigned long b_date = ((const struct commit_list *)b)->item->date;
 400        if (a_date < b_date)
 401                return 1;
 402        if (a_date > b_date)
 403                return -1;
 404        return 0;
 405}
 406
 407static void *commit_list_get_next(const void *a)
 408{
 409        return ((const struct commit_list *)a)->next;
 410}
 411
 412static void commit_list_set_next(void *a, void *next)
 413{
 414        ((struct commit_list *)a)->next = next;
 415}
 416
 417void commit_list_sort_by_date(struct commit_list **list)
 418{
 419        *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
 420                                commit_list_compare_by_date);
 421}
 422
 423struct commit *pop_most_recent_commit(struct commit_list **list,
 424                                      unsigned int mark)
 425{
 426        struct commit *ret = (*list)->item;
 427        struct commit_list *parents = ret->parents;
 428        struct commit_list *old = *list;
 429
 430        *list = (*list)->next;
 431        free(old);
 432
 433        while (parents) {
 434                struct commit *commit = parents->item;
 435                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 436                        commit->object.flags |= mark;
 437                        commit_list_insert_by_date(commit, list);
 438                }
 439                parents = parents->next;
 440        }
 441        return ret;
 442}
 443
 444static void clear_commit_marks_1(struct commit_list **plist,
 445                                 struct commit *commit, unsigned int mark)
 446{
 447        while (commit) {
 448                struct commit_list *parents;
 449
 450                if (!(mark & commit->object.flags))
 451                        return;
 452
 453                commit->object.flags &= ~mark;
 454
 455                parents = commit->parents;
 456                if (!parents)
 457                        return;
 458
 459                while ((parents = parents->next))
 460                        commit_list_insert(parents->item, plist);
 461
 462                commit = commit->parents->item;
 463        }
 464}
 465
 466void clear_commit_marks(struct commit *commit, unsigned int mark)
 467{
 468        struct commit_list *list = NULL;
 469        commit_list_insert(commit, &list);
 470        while (list)
 471                clear_commit_marks_1(&list, pop_commit(&list), mark);
 472}
 473
 474void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 475{
 476        struct object *object;
 477        struct commit *commit;
 478        unsigned int i;
 479
 480        for (i = 0; i < a->nr; i++) {
 481                object = a->objects[i].item;
 482                commit = lookup_commit_reference_gently(object->sha1, 1);
 483                if (commit)
 484                        clear_commit_marks(commit, mark);
 485        }
 486}
 487
 488struct commit *pop_commit(struct commit_list **stack)
 489{
 490        struct commit_list *top = *stack;
 491        struct commit *item = top ? top->item : NULL;
 492
 493        if (top) {
 494                *stack = top->next;
 495                free(top);
 496        }
 497        return item;
 498}
 499
 500/*
 501 * Performs an in-place topological sort on the list supplied.
 502 */
 503void sort_in_topological_order(struct commit_list ** list, int lifo)
 504{
 505        struct commit_list *next, *orig = *list;
 506        struct commit_list *work, **insert;
 507        struct commit_list **pptr;
 508
 509        if (!orig)
 510                return;
 511        *list = NULL;
 512
 513        /* Mark them and clear the indegree */
 514        for (next = orig; next; next = next->next) {
 515                struct commit *commit = next->item;
 516                commit->indegree = 1;
 517        }
 518
 519        /* update the indegree */
 520        for (next = orig; next; next = next->next) {
 521                struct commit_list * parents = next->item->parents;
 522                while (parents) {
 523                        struct commit *parent = parents->item;
 524
 525                        if (parent->indegree)
 526                                parent->indegree++;
 527                        parents = parents->next;
 528                }
 529        }
 530
 531        /*
 532         * find the tips
 533         *
 534         * tips are nodes not reachable from any other node in the list
 535         *
 536         * the tips serve as a starting set for the work queue.
 537         */
 538        work = NULL;
 539        insert = &work;
 540        for (next = orig; next; next = next->next) {
 541                struct commit *commit = next->item;
 542
 543                if (commit->indegree == 1)
 544                        insert = &commit_list_insert(commit, insert)->next;
 545        }
 546
 547        /* process the list in topological order */
 548        if (!lifo)
 549                commit_list_sort_by_date(&work);
 550
 551        pptr = list;
 552        *list = NULL;
 553        while (work) {
 554                struct commit *commit;
 555                struct commit_list *parents, *work_item;
 556
 557                work_item = work;
 558                work = work_item->next;
 559                work_item->next = NULL;
 560
 561                commit = work_item->item;
 562                for (parents = commit->parents; parents ; parents = parents->next) {
 563                        struct commit *parent = parents->item;
 564
 565                        if (!parent->indegree)
 566                                continue;
 567
 568                        /*
 569                         * parents are only enqueued for emission
 570                         * when all their children have been emitted thereby
 571                         * guaranteeing topological order.
 572                         */
 573                        if (--parent->indegree == 1) {
 574                                if (!lifo)
 575                                        commit_list_insert_by_date(parent, &work);
 576                                else
 577                                        commit_list_insert(parent, &work);
 578                        }
 579                }
 580                /*
 581                 * work_item is a commit all of whose children
 582                 * have already been emitted. we can emit it now.
 583                 */
 584                commit->indegree = 0;
 585                *pptr = work_item;
 586                pptr = &work_item->next;
 587        }
 588}
 589
 590/* merge-base stuff */
 591
 592/* bits #0..15 in revision.h */
 593#define PARENT1         (1u<<16)
 594#define PARENT2         (1u<<17)
 595#define STALE           (1u<<18)
 596#define RESULT          (1u<<19)
 597
 598static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 599
 600static struct commit *interesting(struct commit_list *list)
 601{
 602        while (list) {
 603                struct commit *commit = list->item;
 604                list = list->next;
 605                if (commit->object.flags & STALE)
 606                        continue;
 607                return commit;
 608        }
 609        return NULL;
 610}
 611
 612static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 613{
 614        struct commit_list *list = NULL;
 615        struct commit_list *result = NULL;
 616        int i;
 617
 618        one->object.flags |= PARENT1;
 619        commit_list_insert_by_date(one, &list);
 620        for (i = 0; i < n; i++) {
 621                twos[i]->object.flags |= PARENT2;
 622                commit_list_insert_by_date(twos[i], &list);
 623        }
 624
 625        while (interesting(list)) {
 626                struct commit *commit;
 627                struct commit_list *parents;
 628                struct commit_list *next;
 629                int flags;
 630
 631                commit = list->item;
 632                next = list->next;
 633                free(list);
 634                list = next;
 635
 636                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 637                if (flags == (PARENT1 | PARENT2)) {
 638                        if (!(commit->object.flags & RESULT)) {
 639                                commit->object.flags |= RESULT;
 640                                commit_list_insert_by_date(commit, &result);
 641                        }
 642                        /* Mark parents of a found merge stale */
 643                        flags |= STALE;
 644                }
 645                parents = commit->parents;
 646                while (parents) {
 647                        struct commit *p = parents->item;
 648                        parents = parents->next;
 649                        if ((p->object.flags & flags) == flags)
 650                                continue;
 651                        if (parse_commit(p))
 652                                return NULL;
 653                        p->object.flags |= flags;
 654                        commit_list_insert_by_date(p, &list);
 655                }
 656        }
 657
 658        free_commit_list(list);
 659        return result;
 660}
 661
 662static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 663{
 664        struct commit_list *list = NULL;
 665        struct commit_list *result = NULL;
 666        int i;
 667
 668        for (i = 0; i < n; i++) {
 669                if (one == twos[i])
 670                        /*
 671                         * We do not mark this even with RESULT so we do not
 672                         * have to clean it up.
 673                         */
 674                        return commit_list_insert(one, &result);
 675        }
 676
 677        if (parse_commit(one))
 678                return NULL;
 679        for (i = 0; i < n; i++) {
 680                if (parse_commit(twos[i]))
 681                        return NULL;
 682        }
 683
 684        list = paint_down_to_common(one, n, twos);
 685
 686        while (list) {
 687                struct commit_list *next = list->next;
 688                if (!(list->item->object.flags & STALE))
 689                        commit_list_insert_by_date(list->item, &result);
 690                free(list);
 691                list = next;
 692        }
 693        return result;
 694}
 695
 696struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 697{
 698        struct commit_list *i, *j, *k, *ret = NULL;
 699        struct commit_list **pptr = &ret;
 700
 701        for (i = in; i; i = i->next) {
 702                if (!ret)
 703                        pptr = &commit_list_insert(i->item, pptr)->next;
 704                else {
 705                        struct commit_list *new = NULL, *end = NULL;
 706
 707                        for (j = ret; j; j = j->next) {
 708                                struct commit_list *bases;
 709                                bases = get_merge_bases(i->item, j->item, 1);
 710                                if (!new)
 711                                        new = bases;
 712                                else
 713                                        end->next = bases;
 714                                for (k = bases; k; k = k->next)
 715                                        end = k;
 716                        }
 717                        ret = new;
 718                }
 719        }
 720        return ret;
 721}
 722
 723static int remove_redundant(struct commit **array, int cnt)
 724{
 725        /*
 726         * Some commit in the array may be an ancestor of
 727         * another commit.  Move such commit to the end of
 728         * the array, and return the number of commits that
 729         * are independent from each other.
 730         */
 731        struct commit **work;
 732        unsigned char *redundant;
 733        int *filled_index;
 734        int i, j, filled;
 735
 736        work = xcalloc(cnt, sizeof(*work));
 737        redundant = xcalloc(cnt, 1);
 738        filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
 739
 740        for (i = 0; i < cnt; i++) {
 741                struct commit_list *common;
 742
 743                if (redundant[i])
 744                        continue;
 745                for (j = filled = 0; j < cnt; j++) {
 746                        if (i == j || redundant[j])
 747                                continue;
 748                        filled_index[filled] = j;
 749                        work[filled++] = array[j];
 750                }
 751                common = paint_down_to_common(array[i], filled, work);
 752                if (array[i]->object.flags & PARENT2)
 753                        redundant[i] = 1;
 754                for (j = 0; j < filled; j++)
 755                        if (work[j]->object.flags & PARENT1)
 756                                redundant[filled_index[j]] = 1;
 757                clear_commit_marks(array[i], all_flags);
 758                for (j = 0; j < filled; j++)
 759                        clear_commit_marks(work[j], all_flags);
 760                free_commit_list(common);
 761        }
 762
 763        /* Now collect the result */
 764        memcpy(work, array, sizeof(*array) * cnt);
 765        for (i = filled = 0; i < cnt; i++)
 766                if (!redundant[i])
 767                        array[filled++] = work[i];
 768        for (j = filled, i = 0; i < cnt; i++)
 769                if (redundant[i])
 770                        array[j++] = work[i];
 771        free(work);
 772        free(redundant);
 773        free(filled_index);
 774        return filled;
 775}
 776
 777struct commit_list *get_merge_bases_many(struct commit *one,
 778                                         int n,
 779                                         struct commit **twos,
 780                                         int cleanup)
 781{
 782        struct commit_list *list;
 783        struct commit **rslt;
 784        struct commit_list *result;
 785        int cnt, i;
 786
 787        result = merge_bases_many(one, n, twos);
 788        for (i = 0; i < n; i++) {
 789                if (one == twos[i])
 790                        return result;
 791        }
 792        if (!result || !result->next) {
 793                if (cleanup) {
 794                        clear_commit_marks(one, all_flags);
 795                        for (i = 0; i < n; i++)
 796                                clear_commit_marks(twos[i], all_flags);
 797                }
 798                return result;
 799        }
 800
 801        /* There are more than one */
 802        cnt = 0;
 803        list = result;
 804        while (list) {
 805                list = list->next;
 806                cnt++;
 807        }
 808        rslt = xcalloc(cnt, sizeof(*rslt));
 809        for (list = result, i = 0; list; list = list->next)
 810                rslt[i++] = list->item;
 811        free_commit_list(result);
 812
 813        clear_commit_marks(one, all_flags);
 814        for (i = 0; i < n; i++)
 815                clear_commit_marks(twos[i], all_flags);
 816
 817        cnt = remove_redundant(rslt, cnt);
 818        result = NULL;
 819        for (i = 0; i < cnt; i++)
 820                commit_list_insert_by_date(rslt[i], &result);
 821        free(rslt);
 822        return result;
 823}
 824
 825struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 826                                    int cleanup)
 827{
 828        return get_merge_bases_many(one, 1, &two, cleanup);
 829}
 830
 831/*
 832 * Is "commit" a decendant of one of the elements on the "with_commit" list?
 833 */
 834int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 835{
 836        if (!with_commit)
 837                return 1;
 838        while (with_commit) {
 839                struct commit *other;
 840
 841                other = with_commit->item;
 842                with_commit = with_commit->next;
 843                if (in_merge_bases(other, commit))
 844                        return 1;
 845        }
 846        return 0;
 847}
 848
 849/*
 850 * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 851 */
 852int in_merge_bases(struct commit *commit, struct commit *reference)
 853{
 854        struct commit_list *bases;
 855        int ret = 0;
 856
 857        if (parse_commit(commit) || parse_commit(reference))
 858                return ret;
 859
 860        bases = paint_down_to_common(commit, 1, &reference);
 861        if (commit->object.flags & PARENT2)
 862                ret = 1;
 863        clear_commit_marks(commit, all_flags);
 864        clear_commit_marks(reference, all_flags);
 865        free_commit_list(bases);
 866        return ret;
 867}
 868
 869struct commit_list *reduce_heads(struct commit_list *heads)
 870{
 871        struct commit_list *p;
 872        struct commit_list *result = NULL, **tail = &result;
 873        struct commit **array;
 874        int num_head, i;
 875
 876        if (!heads)
 877                return NULL;
 878
 879        /* Uniquify */
 880        for (p = heads; p; p = p->next)
 881                p->item->object.flags &= ~STALE;
 882        for (p = heads, num_head = 0; p; p = p->next) {
 883                if (p->item->object.flags & STALE)
 884                        continue;
 885                p->item->object.flags |= STALE;
 886                num_head++;
 887        }
 888        array = xcalloc(sizeof(*array), num_head);
 889        for (p = heads, i = 0; p; p = p->next) {
 890                if (p->item->object.flags & STALE) {
 891                        array[i++] = p->item;
 892                        p->item->object.flags &= ~STALE;
 893                }
 894        }
 895        num_head = remove_redundant(array, num_head);
 896        for (i = 0; i < num_head; i++)
 897                tail = &commit_list_insert(array[i], tail)->next;
 898        return result;
 899}
 900
 901static const char gpg_sig_header[] = "gpgsig";
 902static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 903
 904static int do_sign_commit(struct strbuf *buf, const char *keyid)
 905{
 906        struct strbuf sig = STRBUF_INIT;
 907        int inspos, copypos;
 908
 909        /* find the end of the header */
 910        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
 911
 912        if (!keyid || !*keyid)
 913                keyid = get_signing_key();
 914        if (sign_buffer(buf, &sig, keyid)) {
 915                strbuf_release(&sig);
 916                return -1;
 917        }
 918
 919        for (copypos = 0; sig.buf[copypos]; ) {
 920                const char *bol = sig.buf + copypos;
 921                const char *eol = strchrnul(bol, '\n');
 922                int len = (eol - bol) + !!*eol;
 923
 924                if (!copypos) {
 925                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
 926                        inspos += gpg_sig_header_len;
 927                }
 928                strbuf_insert(buf, inspos++, " ", 1);
 929                strbuf_insert(buf, inspos, bol, len);
 930                inspos += len;
 931                copypos += len;
 932        }
 933        strbuf_release(&sig);
 934        return 0;
 935}
 936
 937int parse_signed_commit(const unsigned char *sha1,
 938                        struct strbuf *payload, struct strbuf *signature)
 939{
 940        unsigned long size;
 941        enum object_type type;
 942        char *buffer = read_sha1_file(sha1, &type, &size);
 943        int in_signature, saw_signature = -1;
 944        char *line, *tail;
 945
 946        if (!buffer || type != OBJ_COMMIT)
 947                goto cleanup;
 948
 949        line = buffer;
 950        tail = buffer + size;
 951        in_signature = 0;
 952        saw_signature = 0;
 953        while (line < tail) {
 954                const char *sig = NULL;
 955                char *next = memchr(line, '\n', tail - line);
 956
 957                next = next ? next + 1 : tail;
 958                if (in_signature && line[0] == ' ')
 959                        sig = line + 1;
 960                else if (!prefixcmp(line, gpg_sig_header) &&
 961                         line[gpg_sig_header_len] == ' ')
 962                        sig = line + gpg_sig_header_len + 1;
 963                if (sig) {
 964                        strbuf_add(signature, sig, next - sig);
 965                        saw_signature = 1;
 966                        in_signature = 1;
 967                } else {
 968                        if (*line == '\n')
 969                                /* dump the whole remainder of the buffer */
 970                                next = tail;
 971                        strbuf_add(payload, line, next - line);
 972                        in_signature = 0;
 973                }
 974                line = next;
 975        }
 976 cleanup:
 977        free(buffer);
 978        return saw_signature;
 979}
 980
 981static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 982{
 983        struct merge_remote_desc *desc;
 984        struct commit_extra_header *mergetag;
 985        char *buf;
 986        unsigned long size, len;
 987        enum object_type type;
 988
 989        desc = merge_remote_util(parent);
 990        if (!desc || !desc->obj)
 991                return;
 992        buf = read_sha1_file(desc->obj->sha1, &type, &size);
 993        if (!buf || type != OBJ_TAG)
 994                goto free_return;
 995        len = parse_signature(buf, size);
 996        if (size == len)
 997                goto free_return;
 998        /*
 999         * We could verify this signature and either omit the tag when
1000         * it does not validate, but the integrator may not have the
1001         * public key of the signer of the tag he is merging, while a
1002         * later auditor may have it while auditing, so let's not run
1003         * verify-signed-buffer here for now...
1004         *
1005         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
1006         *      warn("warning: signed tag unverified.");
1007         */
1008        mergetag = xcalloc(1, sizeof(*mergetag));
1009        mergetag->key = xstrdup("mergetag");
1010        mergetag->value = buf;
1011        mergetag->len = size;
1012
1013        **tail = mergetag;
1014        *tail = &mergetag->next;
1015        return;
1016
1017free_return:
1018        free(buf);
1019}
1020
1021void append_merge_tag_headers(struct commit_list *parents,
1022                              struct commit_extra_header ***tail)
1023{
1024        while (parents) {
1025                struct commit *parent = parents->item;
1026                handle_signed_tag(parent, tail);
1027                parents = parents->next;
1028        }
1029}
1030
1031static void add_extra_header(struct strbuf *buffer,
1032                             struct commit_extra_header *extra)
1033{
1034        strbuf_addstr(buffer, extra->key);
1035        if (extra->len)
1036                strbuf_add_lines(buffer, " ", extra->value, extra->len);
1037        else
1038                strbuf_addch(buffer, '\n');
1039}
1040
1041struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
1042                                                      const char **exclude)
1043{
1044        struct commit_extra_header *extra = NULL;
1045        unsigned long size;
1046        enum object_type type;
1047        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
1048        if (buffer && type == OBJ_COMMIT)
1049                extra = read_commit_extra_header_lines(buffer, size, exclude);
1050        free(buffer);
1051        return extra;
1052}
1053
1054static inline int standard_header_field(const char *field, size_t len)
1055{
1056        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1057                (len == 6 && !memcmp(field, "parent ", 7)) ||
1058                (len == 6 && !memcmp(field, "author ", 7)) ||
1059                (len == 9 && !memcmp(field, "committer ", 10)) ||
1060                (len == 8 && !memcmp(field, "encoding ", 9)));
1061}
1062
1063static int excluded_header_field(const char *field, size_t len, const char **exclude)
1064{
1065        if (!exclude)
1066                return 0;
1067
1068        while (*exclude) {
1069                size_t xlen = strlen(*exclude);
1070                if (len == xlen &&
1071                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1072                        return 1;
1073                exclude++;
1074        }
1075        return 0;
1076}
1077
1078static struct commit_extra_header *read_commit_extra_header_lines(
1079        const char *buffer, size_t size,
1080        const char **exclude)
1081{
1082        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1083        const char *line, *next, *eof, *eob;
1084        struct strbuf buf = STRBUF_INIT;
1085
1086        for (line = buffer, eob = line + size;
1087             line < eob && *line != '\n';
1088             line = next) {
1089                next = memchr(line, '\n', eob - line);
1090                next = next ? next + 1 : eob;
1091                if (*line == ' ') {
1092                        /* continuation */
1093                        if (it)
1094                                strbuf_add(&buf, line + 1, next - (line + 1));
1095                        continue;
1096                }
1097                if (it)
1098                        it->value = strbuf_detach(&buf, &it->len);
1099                strbuf_reset(&buf);
1100                it = NULL;
1101
1102                eof = strchr(line, ' ');
1103                if (next <= eof)
1104                        eof = next;
1105
1106                if (standard_header_field(line, eof - line) ||
1107                    excluded_header_field(line, eof - line, exclude))
1108                        continue;
1109
1110                it = xcalloc(1, sizeof(*it));
1111                it->key = xmemdupz(line, eof-line);
1112                *tail = it;
1113                tail = &it->next;
1114                if (eof + 1 < next)
1115                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1116        }
1117        if (it)
1118                it->value = strbuf_detach(&buf, &it->len);
1119        return extra;
1120}
1121
1122void free_commit_extra_headers(struct commit_extra_header *extra)
1123{
1124        while (extra) {
1125                struct commit_extra_header *next = extra->next;
1126                free(extra->key);
1127                free(extra->value);
1128                free(extra);
1129                extra = next;
1130        }
1131}
1132
1133int commit_tree(const struct strbuf *msg, unsigned char *tree,
1134                struct commit_list *parents, unsigned char *ret,
1135                const char *author, const char *sign_commit)
1136{
1137        struct commit_extra_header *extra = NULL, **tail = &extra;
1138        int result;
1139
1140        append_merge_tag_headers(parents, &tail);
1141        result = commit_tree_extended(msg, tree, parents, ret,
1142                                      author, sign_commit, extra);
1143        free_commit_extra_headers(extra);
1144        return result;
1145}
1146
1147static int find_invalid_utf8(const char *buf, int len)
1148{
1149        int offset = 0;
1150
1151        while (len) {
1152                unsigned char c = *buf++;
1153                int bytes, bad_offset;
1154
1155                len--;
1156                offset++;
1157
1158                /* Simple US-ASCII? No worries. */
1159                if (c < 0x80)
1160                        continue;
1161
1162                bad_offset = offset-1;
1163
1164                /*
1165                 * Count how many more high bits set: that's how
1166                 * many more bytes this sequence should have.
1167                 */
1168                bytes = 0;
1169                while (c & 0x40) {
1170                        c <<= 1;
1171                        bytes++;
1172                }
1173
1174                /* Must be between 1 and 5 more bytes */
1175                if (bytes < 1 || bytes > 5)
1176                        return bad_offset;
1177
1178                /* Do we *have* that many bytes? */
1179                if (len < bytes)
1180                        return bad_offset;
1181
1182                offset += bytes;
1183                len -= bytes;
1184
1185                /* And verify that they are good continuation bytes */
1186                do {
1187                        if ((*buf++ & 0xc0) != 0x80)
1188                                return bad_offset;
1189                } while (--bytes);
1190
1191                /* We could/should check the value and length here too */
1192        }
1193        return -1;
1194}
1195
1196/*
1197 * This verifies that the buffer is in proper utf8 format.
1198 *
1199 * If it isn't, it assumes any non-utf8 characters are Latin1,
1200 * and does the conversion.
1201 *
1202 * Fixme: we should probably also disallow overlong forms and
1203 * invalid characters. But we don't do that currently.
1204 */
1205static int verify_utf8(struct strbuf *buf)
1206{
1207        int ok = 1;
1208        long pos = 0;
1209
1210        for (;;) {
1211                int bad;
1212                unsigned char c;
1213                unsigned char replace[2];
1214
1215                bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
1216                if (bad < 0)
1217                        return ok;
1218                pos += bad;
1219                ok = 0;
1220                c = buf->buf[pos];
1221                strbuf_remove(buf, pos, 1);
1222
1223                /* We know 'c' must be in the range 128-255 */
1224                replace[0] = 0xc0 + (c >> 6);
1225                replace[1] = 0x80 + (c & 0x3f);
1226                strbuf_insert(buf, pos, replace, 2);
1227                pos += 2;
1228        }
1229}
1230
1231static const char commit_utf8_warn[] =
1232"Warning: commit message did not conform to UTF-8.\n"
1233"You may want to amend it after fixing the message, or set the config\n"
1234"variable i18n.commitencoding to the encoding your project uses.\n";
1235
1236int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1237                         struct commit_list *parents, unsigned char *ret,
1238                         const char *author, const char *sign_commit,
1239                         struct commit_extra_header *extra)
1240{
1241        int result;
1242        int encoding_is_utf8;
1243        struct strbuf buffer;
1244
1245        assert_sha1_type(tree, OBJ_TREE);
1246
1247        if (memchr(msg->buf, '\0', msg->len))
1248                return error("a NUL byte in commit log message not allowed.");
1249
1250        /* Not having i18n.commitencoding is the same as having utf-8 */
1251        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1252
1253        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1254        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1255
1256        /*
1257         * NOTE! This ordering means that the same exact tree merged with a
1258         * different order of parents will be a _different_ changeset even
1259         * if everything else stays the same.
1260         */
1261        while (parents) {
1262                struct commit_list *next = parents->next;
1263                struct commit *parent = parents->item;
1264
1265                strbuf_addf(&buffer, "parent %s\n",
1266                            sha1_to_hex(parent->object.sha1));
1267                free(parents);
1268                parents = next;
1269        }
1270
1271        /* Person/date information */
1272        if (!author)
1273                author = git_author_info(IDENT_STRICT);
1274        strbuf_addf(&buffer, "author %s\n", author);
1275        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
1276        if (!encoding_is_utf8)
1277                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1278
1279        while (extra) {
1280                add_extra_header(&buffer, extra);
1281                extra = extra->next;
1282        }
1283        strbuf_addch(&buffer, '\n');
1284
1285        /* And add the comment */
1286        strbuf_addbuf(&buffer, msg);
1287
1288        /* And check the encoding */
1289        if (encoding_is_utf8 && !verify_utf8(&buffer))
1290                fprintf(stderr, commit_utf8_warn);
1291
1292        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1293                return -1;
1294
1295        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1296        strbuf_release(&buffer);
1297        return result;
1298}
1299
1300struct commit *get_merge_parent(const char *name)
1301{
1302        struct object *obj;
1303        struct commit *commit;
1304        unsigned char sha1[20];
1305        if (get_sha1(name, sha1))
1306                return NULL;
1307        obj = parse_object(sha1);
1308        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1309        if (commit && !commit->util) {
1310                struct merge_remote_desc *desc;
1311                desc = xmalloc(sizeof(*desc));
1312                desc->obj = obj;
1313                desc->name = strdup(name);
1314                commit->util = desc;
1315        }
1316        return commit;
1317}
1318
1319/*
1320 * Append a commit to the end of the commit_list.
1321 *
1322 * next starts by pointing to the variable that holds the head of an
1323 * empty commit_list, and is updated to point to the "next" field of
1324 * the last item on the list as new commits are appended.
1325 *
1326 * Usage example:
1327 *
1328 *     struct commit_list *list;
1329 *     struct commit_list **next = &list;
1330 *
1331 *     next = commit_list_append(c1, next);
1332 *     next = commit_list_append(c2, next);
1333 *     assert(commit_list_count(list) == 2);
1334 *     return list;
1335 */
1336struct commit_list **commit_list_append(struct commit *commit,
1337                                        struct commit_list **next)
1338{
1339        struct commit_list *new = xmalloc(sizeof(struct commit_list));
1340        new->item = commit;
1341        *next = new;
1342        new->next = NULL;
1343        return &new->next;
1344}