Andrew's git / gitweb.git / commit.c
?
commit.con commit man: rearrange git synopsis to fit in 80 lines (68e4b55)
   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
  11int save_commit_buffer = 1;
  12
  13const char *commit_type = "commit";
  14
  15static struct commit *check_commit(struct object *obj,
  16                                   const unsigned char *sha1,
  17                                   int quiet)
  18{
  19        if (obj->type != OBJ_COMMIT) {
  20                if (!quiet)
  21                        error("Object %s is a %s, not a commit",
  22                              sha1_to_hex(sha1), typename(obj->type));
  23                return NULL;
  24        }
  25        return (struct commit *) obj;
  26}
  27
  28struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
  29                                              int quiet)
  30{
  31        struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
  32
  33        if (!obj)
  34                return NULL;
  35        return check_commit(obj, sha1, quiet);
  36}
  37
  38struct commit *lookup_commit_reference(const unsigned char *sha1)
  39{
  40        return lookup_commit_reference_gently(sha1, 0);
  41}
  42
  43struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
  44{
  45        struct commit *c = lookup_commit_reference(sha1);
  46        if (!c)
  47                die(_("could not parse %s"), ref_name);
  48        if (hashcmp(sha1, c->object.sha1)) {
  49                warning(_("%s %s is not a commit!"),
  50                        ref_name, sha1_to_hex(sha1));
  51        }
  52        return c;
  53}
  54
  55struct commit *lookup_commit(const unsigned char *sha1)
  56{
  57        struct object *obj = lookup_object(sha1);
  58        if (!obj)
  59                return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
  60        if (!obj->type)
  61                obj->type = OBJ_COMMIT;
  62        return check_commit(obj, sha1, 0);
  63}
  64
  65struct commit *lookup_commit_reference_by_name(const char *name)
  66{
  67        unsigned char sha1[20];
  68        struct commit *commit;
  69
  70        if (get_sha1(name, sha1))
  71                return NULL;
  72        commit = lookup_commit_reference(sha1);
  73        if (!commit || parse_commit(commit))
  74                return NULL;
  75        return commit;
  76}
  77
  78static unsigned long parse_commit_date(const char *buf, const char *tail)
  79{
  80        const char *dateptr;
  81
  82        if (buf + 6 >= tail)
  83                return 0;
  84        if (memcmp(buf, "author", 6))
  85                return 0;
  86        while (buf < tail && *buf++ != '\n')
  87                /* nada */;
  88        if (buf + 9 >= tail)
  89                return 0;
  90        if (memcmp(buf, "committer", 9))
  91                return 0;
  92        while (buf < tail && *buf++ != '>')
  93                /* nada */;
  94        if (buf >= tail)
  95                return 0;
  96        dateptr = buf;
  97        while (buf < tail && *buf++ != '\n')
  98                /* nada */;
  99        if (buf >= tail)
 100                return 0;
 101        /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
 102        return strtoul(dateptr, NULL, 10);
 103}
 104
 105static struct commit_graft **commit_graft;
 106static int commit_graft_alloc, commit_graft_nr;
 107
 108static int commit_graft_pos(const unsigned char *sha1)
 109{
 110        int lo, hi;
 111        lo = 0;
 112        hi = commit_graft_nr;
 113        while (lo < hi) {
 114                int mi = (lo + hi) / 2;
 115                struct commit_graft *graft = commit_graft[mi];
 116                int cmp = hashcmp(sha1, graft->sha1);
 117                if (!cmp)
 118                        return mi;
 119                if (cmp < 0)
 120                        hi = mi;
 121                else
 122                        lo = mi + 1;
 123        }
 124        return -lo - 1;
 125}
 126
 127int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 128{
 129        int pos = commit_graft_pos(graft->sha1);
 130
 131        if (0 <= pos) {
 132                if (ignore_dups)
 133                        free(graft);
 134                else {
 135                        free(commit_graft[pos]);
 136                        commit_graft[pos] = graft;
 137                }
 138                return 1;
 139        }
 140        pos = -pos - 1;
 141        if (commit_graft_alloc <= ++commit_graft_nr) {
 142                commit_graft_alloc = alloc_nr(commit_graft_alloc);
 143                commit_graft = xrealloc(commit_graft,
 144                                        sizeof(*commit_graft) *
 145                                        commit_graft_alloc);
 146        }
 147        if (pos < commit_graft_nr)
 148                memmove(commit_graft + pos + 1,
 149                        commit_graft + pos,
 150                        (commit_graft_nr - pos - 1) *
 151                        sizeof(*commit_graft));
 152        commit_graft[pos] = graft;
 153        return 0;
 154}
 155
 156struct commit_graft *read_graft_line(char *buf, int len)
 157{
 158        /* The format is just "Commit Parent1 Parent2 ...\n" */
 159        int i;
 160        struct commit_graft *graft = NULL;
 161
 162        while (len && isspace(buf[len-1]))
 163                buf[--len] = '\0';
 164        if (buf[0] == '#' || buf[0] == '\0')
 165                return NULL;
 166        if ((len + 1) % 41)
 167                goto bad_graft_data;
 168        i = (len + 1) / 41 - 1;
 169        graft = xmalloc(sizeof(*graft) + 20 * i);
 170        graft->nr_parent = i;
 171        if (get_sha1_hex(buf, graft->sha1))
 172                goto bad_graft_data;
 173        for (i = 40; i < len; i += 41) {
 174                if (buf[i] != ' ')
 175                        goto bad_graft_data;
 176                if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
 177                        goto bad_graft_data;
 178        }
 179        return graft;
 180
 181bad_graft_data:
 182        error("bad graft data: %s", buf);
 183        free(graft);
 184        return NULL;
 185}
 186
 187static int read_graft_file(const char *graft_file)
 188{
 189        FILE *fp = fopen(graft_file, "r");
 190        char buf[1024];
 191        if (!fp)
 192                return -1;
 193        while (fgets(buf, sizeof(buf), fp)) {
 194                /* The format is just "Commit Parent1 Parent2 ...\n" */
 195                int len = strlen(buf);
 196                struct commit_graft *graft = read_graft_line(buf, len);
 197                if (!graft)
 198                        continue;
 199                if (register_commit_graft(graft, 1))
 200                        error("duplicate graft data: %s", buf);
 201        }
 202        fclose(fp);
 203        return 0;
 204}
 205
 206static void prepare_commit_graft(void)
 207{
 208        static int commit_graft_prepared;
 209        char *graft_file;
 210
 211        if (commit_graft_prepared)
 212                return;
 213        graft_file = get_graft_file();
 214        read_graft_file(graft_file);
 215        /* make sure shallows are read */
 216        is_repository_shallow();
 217        commit_graft_prepared = 1;
 218}
 219
 220struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 221{
 222        int pos;
 223        prepare_commit_graft();
 224        pos = commit_graft_pos(sha1);
 225        if (pos < 0)
 226                return NULL;
 227        return commit_graft[pos];
 228}
 229
 230int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
 231{
 232        int i, ret;
 233        for (i = ret = 0; i < commit_graft_nr && !ret; i++)
 234                ret = fn(commit_graft[i], cb_data);
 235        return ret;
 236}
 237
 238int unregister_shallow(const unsigned char *sha1)
 239{
 240        int pos = commit_graft_pos(sha1);
 241        if (pos < 0)
 242                return -1;
 243        if (pos + 1 < commit_graft_nr)
 244                memmove(commit_graft + pos, commit_graft + pos + 1,
 245                                sizeof(struct commit_graft *)
 246                                * (commit_graft_nr - pos - 1));
 247        commit_graft_nr--;
 248        return 0;
 249}
 250
 251int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 252{
 253        const char *tail = buffer;
 254        const char *bufptr = buffer;
 255        unsigned char parent[20];
 256        struct commit_list **pptr;
 257        struct commit_graft *graft;
 258
 259        if (item->object.parsed)
 260                return 0;
 261        item->object.parsed = 1;
 262        tail += size;
 263        if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
 264                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 265        if (get_sha1_hex(bufptr + 5, parent) < 0)
 266                return error("bad tree pointer in commit %s",
 267                             sha1_to_hex(item->object.sha1));
 268        item->tree = lookup_tree(parent);
 269        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 270        pptr = &item->parents;
 271
 272        graft = lookup_commit_graft(item->object.sha1);
 273        while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
 274                struct commit *new_parent;
 275
 276                if (tail <= bufptr + 48 ||
 277                    get_sha1_hex(bufptr + 7, parent) ||
 278                    bufptr[47] != '\n')
 279                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
 280                bufptr += 48;
 281                /*
 282                 * The clone is shallow if nr_parent < 0, and we must
 283                 * not traverse its real parents even when we unhide them.
 284                 */
 285                if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
 286                        continue;
 287                new_parent = lookup_commit(parent);
 288                if (new_parent)
 289                        pptr = &commit_list_insert(new_parent, pptr)->next;
 290        }
 291        if (graft) {
 292                int i;
 293                struct commit *new_parent;
 294                for (i = 0; i < graft->nr_parent; i++) {
 295                        new_parent = lookup_commit(graft->parent[i]);
 296                        if (!new_parent)
 297                                continue;
 298                        pptr = &commit_list_insert(new_parent, pptr)->next;
 299                }
 300        }
 301        item->date = parse_commit_date(bufptr, tail);
 302
 303        return 0;
 304}
 305
 306int parse_commit(struct commit *item)
 307{
 308        enum object_type type;
 309        void *buffer;
 310        unsigned long size;
 311        int ret;
 312
 313        if (!item)
 314                return -1;
 315        if (item->object.parsed)
 316                return 0;
 317        buffer = read_sha1_file(item->object.sha1, &type, &size);
 318        if (!buffer)
 319                return error("Could not read %s",
 320                             sha1_to_hex(item->object.sha1));
 321        if (type != OBJ_COMMIT) {
 322                free(buffer);
 323                return error("Object %s not a commit",
 324                             sha1_to_hex(item->object.sha1));
 325        }
 326        ret = parse_commit_buffer(item, buffer, size);
 327        if (save_commit_buffer && !ret) {
 328                item->buffer = buffer;
 329                return 0;
 330        }
 331        free(buffer);
 332        return ret;
 333}
 334
 335int find_commit_subject(const char *commit_buffer, const char **subject)
 336{
 337        const char *eol;
 338        const char *p = commit_buffer;
 339
 340        while (*p && (*p != '\n' || p[1] != '\n'))
 341                p++;
 342        if (*p) {
 343                p += 2;
 344                for (eol = p; *eol && *eol != '\n'; eol++)
 345                        ; /* do nothing */
 346        } else
 347                eol = p;
 348
 349        *subject = p;
 350
 351        return eol - p;
 352}
 353
 354struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 355{
 356        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 357        new_list->item = item;
 358        new_list->next = *list_p;
 359        *list_p = new_list;
 360        return new_list;
 361}
 362
 363unsigned commit_list_count(const struct commit_list *l)
 364{
 365        unsigned c = 0;
 366        for (; l; l = l->next )
 367                c++;
 368        return c;
 369}
 370
 371void free_commit_list(struct commit_list *list)
 372{
 373        while (list) {
 374                struct commit_list *temp = list;
 375                list = temp->next;
 376                free(temp);
 377        }
 378}
 379
 380struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 381{
 382        struct commit_list **pp = list;
 383        struct commit_list *p;
 384        while ((p = *pp) != NULL) {
 385                if (p->item->date < item->date) {
 386                        break;
 387                }
 388                pp = &p->next;
 389        }
 390        return commit_list_insert(item, pp);
 391}
 392
 393
 394void commit_list_sort_by_date(struct commit_list **list)
 395{
 396        struct commit_list *ret = NULL;
 397        while (*list) {
 398                commit_list_insert_by_date((*list)->item, &ret);
 399                *list = (*list)->next;
 400        }
 401        *list = ret;
 402}
 403
 404struct commit *pop_most_recent_commit(struct commit_list **list,
 405                                      unsigned int mark)
 406{
 407        struct commit *ret = (*list)->item;
 408        struct commit_list *parents = ret->parents;
 409        struct commit_list *old = *list;
 410
 411        *list = (*list)->next;
 412        free(old);
 413
 414        while (parents) {
 415                struct commit *commit = parents->item;
 416                if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 417                        commit->object.flags |= mark;
 418                        commit_list_insert_by_date(commit, list);
 419                }
 420                parents = parents->next;
 421        }
 422        return ret;
 423}
 424
 425void clear_commit_marks(struct commit *commit, unsigned int mark)
 426{
 427        while (commit) {
 428                struct commit_list *parents;
 429
 430                if (!(mark & commit->object.flags))
 431                        return;
 432
 433                commit->object.flags &= ~mark;
 434
 435                parents = commit->parents;
 436                if (!parents)
 437                        return;
 438
 439                while ((parents = parents->next))
 440                        clear_commit_marks(parents->item, mark);
 441
 442                commit = commit->parents->item;
 443        }
 444}
 445
 446void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 447{
 448        struct object *object;
 449        struct commit *commit;
 450        unsigned int i;
 451
 452        for (i = 0; i < a->nr; i++) {
 453                object = a->objects[i].item;
 454                commit = lookup_commit_reference_gently(object->sha1, 1);
 455                if (commit)
 456                        clear_commit_marks(commit, mark);
 457        }
 458}
 459
 460struct commit *pop_commit(struct commit_list **stack)
 461{
 462        struct commit_list *top = *stack;
 463        struct commit *item = top ? top->item : NULL;
 464
 465        if (top) {
 466                *stack = top->next;
 467                free(top);
 468        }
 469        return item;
 470}
 471
 472/*
 473 * Performs an in-place topological sort on the list supplied.
 474 */
 475void sort_in_topological_order(struct commit_list ** list, int lifo)
 476{
 477        struct commit_list *next, *orig = *list;
 478        struct commit_list *work, **insert;
 479        struct commit_list **pptr;
 480
 481        if (!orig)
 482                return;
 483        *list = NULL;
 484
 485        /* Mark them and clear the indegree */
 486        for (next = orig; next; next = next->next) {
 487                struct commit *commit = next->item;
 488                commit->indegree = 1;
 489        }
 490
 491        /* update the indegree */
 492        for (next = orig; next; next = next->next) {
 493                struct commit_list * parents = next->item->parents;
 494                while (parents) {
 495                        struct commit *parent = parents->item;
 496
 497                        if (parent->indegree)
 498                                parent->indegree++;
 499                        parents = parents->next;
 500                }
 501        }
 502
 503        /*
 504         * find the tips
 505         *
 506         * tips are nodes not reachable from any other node in the list
 507         *
 508         * the tips serve as a starting set for the work queue.
 509         */
 510        work = NULL;
 511        insert = &work;
 512        for (next = orig; next; next = next->next) {
 513                struct commit *commit = next->item;
 514
 515                if (commit->indegree == 1)
 516                        insert = &commit_list_insert(commit, insert)->next;
 517        }
 518
 519        /* process the list in topological order */
 520        if (!lifo)
 521                commit_list_sort_by_date(&work);
 522
 523        pptr = list;
 524        *list = NULL;
 525        while (work) {
 526                struct commit *commit;
 527                struct commit_list *parents, *work_item;
 528
 529                work_item = work;
 530                work = work_item->next;
 531                work_item->next = NULL;
 532
 533                commit = work_item->item;
 534                for (parents = commit->parents; parents ; parents = parents->next) {
 535                        struct commit *parent = parents->item;
 536
 537                        if (!parent->indegree)
 538                                continue;
 539
 540                        /*
 541                         * parents are only enqueued for emission
 542                         * when all their children have been emitted thereby
 543                         * guaranteeing topological order.
 544                         */
 545                        if (--parent->indegree == 1) {
 546                                if (!lifo)
 547                                        commit_list_insert_by_date(parent, &work);
 548                                else
 549                                        commit_list_insert(parent, &work);
 550                        }
 551                }
 552                /*
 553                 * work_item is a commit all of whose children
 554                 * have already been emitted. we can emit it now.
 555                 */
 556                commit->indegree = 0;
 557                *pptr = work_item;
 558                pptr = &work_item->next;
 559        }
 560}
 561
 562/* merge-base stuff */
 563
 564/* bits #0..15 in revision.h */
 565#define PARENT1         (1u<<16)
 566#define PARENT2         (1u<<17)
 567#define STALE           (1u<<18)
 568#define RESULT          (1u<<19)
 569
 570static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 571
 572static struct commit *interesting(struct commit_list *list)
 573{
 574        while (list) {
 575                struct commit *commit = list->item;
 576                list = list->next;
 577                if (commit->object.flags & STALE)
 578                        continue;
 579                return commit;
 580        }
 581        return NULL;
 582}
 583
 584static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
 585{
 586        struct commit_list *list = NULL;
 587        struct commit_list *result = NULL;
 588        int i;
 589
 590        for (i = 0; i < n; i++) {
 591                if (one == twos[i])
 592                        /*
 593                         * We do not mark this even with RESULT so we do not
 594                         * have to clean it up.
 595                         */
 596                        return commit_list_insert(one, &result);
 597        }
 598
 599        if (parse_commit(one))
 600                return NULL;
 601        for (i = 0; i < n; i++) {
 602                if (parse_commit(twos[i]))
 603                        return NULL;
 604        }
 605
 606        one->object.flags |= PARENT1;
 607        commit_list_insert_by_date(one, &list);
 608        for (i = 0; i < n; i++) {
 609                twos[i]->object.flags |= PARENT2;
 610                commit_list_insert_by_date(twos[i], &list);
 611        }
 612
 613        while (interesting(list)) {
 614                struct commit *commit;
 615                struct commit_list *parents;
 616                struct commit_list *next;
 617                int flags;
 618
 619                commit = list->item;
 620                next = list->next;
 621                free(list);
 622                list = next;
 623
 624                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
 625                if (flags == (PARENT1 | PARENT2)) {
 626                        if (!(commit->object.flags & RESULT)) {
 627                                commit->object.flags |= RESULT;
 628                                commit_list_insert_by_date(commit, &result);
 629                        }
 630                        /* Mark parents of a found merge stale */
 631                        flags |= STALE;
 632                }
 633                parents = commit->parents;
 634                while (parents) {
 635                        struct commit *p = parents->item;
 636                        parents = parents->next;
 637                        if ((p->object.flags & flags) == flags)
 638                                continue;
 639                        if (parse_commit(p))
 640                                return NULL;
 641                        p->object.flags |= flags;
 642                        commit_list_insert_by_date(p, &list);
 643                }
 644        }
 645
 646        /* Clean up the result to remove stale ones */
 647        free_commit_list(list);
 648        list = result; result = NULL;
 649        while (list) {
 650                struct commit_list *next = list->next;
 651                if (!(list->item->object.flags & STALE))
 652                        commit_list_insert_by_date(list->item, &result);
 653                free(list);
 654                list = next;
 655        }
 656        return result;
 657}
 658
 659struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 660{
 661        struct commit_list *i, *j, *k, *ret = NULL;
 662        struct commit_list **pptr = &ret;
 663
 664        for (i = in; i; i = i->next) {
 665                if (!ret)
 666                        pptr = &commit_list_insert(i->item, pptr)->next;
 667                else {
 668                        struct commit_list *new = NULL, *end = NULL;
 669
 670                        for (j = ret; j; j = j->next) {
 671                                struct commit_list *bases;
 672                                bases = get_merge_bases(i->item, j->item, 1);
 673                                if (!new)
 674                                        new = bases;
 675                                else
 676                                        end->next = bases;
 677                                for (k = bases; k; k = k->next)
 678                                        end = k;
 679                        }
 680                        ret = new;
 681                }
 682        }
 683        return ret;
 684}
 685
 686struct commit_list *get_merge_bases_many(struct commit *one,
 687                                         int n,
 688                                         struct commit **twos,
 689                                         int cleanup)
 690{
 691        struct commit_list *list;
 692        struct commit **rslt;
 693        struct commit_list *result;
 694        int cnt, i, j;
 695
 696        result = merge_bases_many(one, n, twos);
 697        for (i = 0; i < n; i++) {
 698                if (one == twos[i])
 699                        return result;
 700        }
 701        if (!result || !result->next) {
 702                if (cleanup) {
 703                        clear_commit_marks(one, all_flags);
 704                        for (i = 0; i < n; i++)
 705                                clear_commit_marks(twos[i], all_flags);
 706                }
 707                return result;
 708        }
 709
 710        /* There are more than one */
 711        cnt = 0;
 712        list = result;
 713        while (list) {
 714                list = list->next;
 715                cnt++;
 716        }
 717        rslt = xcalloc(cnt, sizeof(*rslt));
 718        for (list = result, i = 0; list; list = list->next)
 719                rslt[i++] = list->item;
 720        free_commit_list(result);
 721
 722        clear_commit_marks(one, all_flags);
 723        for (i = 0; i < n; i++)
 724                clear_commit_marks(twos[i], all_flags);
 725        for (i = 0; i < cnt - 1; i++) {
 726                for (j = i+1; j < cnt; j++) {
 727                        if (!rslt[i] || !rslt[j])
 728                                continue;
 729                        result = merge_bases_many(rslt[i], 1, &rslt[j]);
 730                        clear_commit_marks(rslt[i], all_flags);
 731                        clear_commit_marks(rslt[j], all_flags);
 732                        for (list = result; list; list = list->next) {
 733                                if (rslt[i] == list->item)
 734                                        rslt[i] = NULL;
 735                                if (rslt[j] == list->item)
 736                                        rslt[j] = NULL;
 737                        }
 738                }
 739        }
 740
 741        /* Surviving ones in rslt[] are the independent results */
 742        result = NULL;
 743        for (i = 0; i < cnt; i++) {
 744                if (rslt[i])
 745                        commit_list_insert_by_date(rslt[i], &result);
 746        }
 747        free(rslt);
 748        return result;
 749}
 750
 751struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 752                                    int cleanup)
 753{
 754        return get_merge_bases_many(one, 1, &two, cleanup);
 755}
 756
 757int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 758{
 759        if (!with_commit)
 760                return 1;
 761        while (with_commit) {
 762                struct commit *other;
 763
 764                other = with_commit->item;
 765                with_commit = with_commit->next;
 766                if (in_merge_bases(other, &commit, 1))
 767                        return 1;
 768        }
 769        return 0;
 770}
 771
 772int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 773{
 774        struct commit_list *bases, *b;
 775        int ret = 0;
 776
 777        if (num == 1)
 778                bases = get_merge_bases(commit, *reference, 1);
 779        else
 780                die("not yet");
 781        for (b = bases; b; b = b->next) {
 782                if (!hashcmp(commit->object.sha1, b->item->object.sha1)) {
 783                        ret = 1;
 784                        break;
 785                }
 786        }
 787
 788        free_commit_list(bases);
 789        return ret;
 790}
 791
 792struct commit_list *reduce_heads(struct commit_list *heads)
 793{
 794        struct commit_list *p;
 795        struct commit_list *result = NULL, **tail = &result;
 796        struct commit **other;
 797        size_t num_head, num_other;
 798
 799        if (!heads)
 800                return NULL;
 801
 802        /* Avoid unnecessary reallocations */
 803        for (p = heads, num_head = 0; p; p = p->next)
 804                num_head++;
 805        other = xcalloc(sizeof(*other), num_head);
 806
 807        /* For each commit, see if it can be reached by others */
 808        for (p = heads; p; p = p->next) {
 809                struct commit_list *q, *base;
 810
 811                /* Do we already have this in the result? */
 812                for (q = result; q; q = q->next)
 813                        if (p->item == q->item)
 814                                break;
 815                if (q)
 816                        continue;
 817
 818                num_other = 0;
 819                for (q = heads; q; q = q->next) {
 820                        if (p->item == q->item)
 821                                continue;
 822                        other[num_other++] = q->item;
 823                }
 824                if (num_other)
 825                        base = get_merge_bases_many(p->item, num_other, other, 1);
 826                else
 827                        base = NULL;
 828                /*
 829                 * If p->item does not have anything common with other
 830                 * commits, there won't be any merge base.  If it is
 831                 * reachable from some of the others, p->item will be
 832                 * the merge base.  If its history is connected with
 833                 * others, but p->item is not reachable by others, we
 834                 * will get something other than p->item back.
 835                 */
 836                if (!base || (base->item != p->item))
 837                        tail = &(commit_list_insert(p->item, tail)->next);
 838                free_commit_list(base);
 839        }
 840        free(other);
 841        return result;
 842}
 843
 844static const char gpg_sig_header[] = "gpgsig";
 845static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 846
 847static int do_sign_commit(struct strbuf *buf, const char *keyid)
 848{
 849        struct strbuf sig = STRBUF_INIT;
 850        int inspos, copypos;
 851
 852        /* find the end of the header */
 853        inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
 854
 855        if (!keyid || !*keyid)
 856                keyid = get_signing_key();
 857        if (sign_buffer(buf, &sig, keyid)) {
 858                strbuf_release(&sig);
 859                return -1;
 860        }
 861
 862        for (copypos = 0; sig.buf[copypos]; ) {
 863                const char *bol = sig.buf + copypos;
 864                const char *eol = strchrnul(bol, '\n');
 865                int len = (eol - bol) + !!*eol;
 866
 867                if (!copypos) {
 868                        strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
 869                        inspos += gpg_sig_header_len;
 870                }
 871                strbuf_insert(buf, inspos++, " ", 1);
 872                strbuf_insert(buf, inspos, bol, len);
 873                inspos += len;
 874                copypos += len;
 875        }
 876        strbuf_release(&sig);
 877        return 0;
 878}
 879
 880int parse_signed_commit(const unsigned char *sha1,
 881                        struct strbuf *payload, struct strbuf *signature)
 882{
 883        unsigned long size;
 884        enum object_type type;
 885        char *buffer = read_sha1_file(sha1, &type, &size);
 886        int in_signature, saw_signature = -1;
 887        char *line, *tail;
 888
 889        if (!buffer || type != OBJ_COMMIT)
 890                goto cleanup;
 891
 892        line = buffer;
 893        tail = buffer + size;
 894        in_signature = 0;
 895        saw_signature = 0;
 896        while (line < tail) {
 897                const char *sig = NULL;
 898                char *next = memchr(line, '\n', tail - line);
 899
 900                next = next ? next + 1 : tail;
 901                if (in_signature && line[0] == ' ')
 902                        sig = line + 1;
 903                else if (!prefixcmp(line, gpg_sig_header) &&
 904                         line[gpg_sig_header_len] == ' ')
 905                        sig = line + gpg_sig_header_len + 1;
 906                if (sig) {
 907                        strbuf_add(signature, sig, next - sig);
 908                        saw_signature = 1;
 909                        in_signature = 1;
 910                } else {
 911                        if (*line == '\n')
 912                                /* dump the whole remainder of the buffer */
 913                                next = tail;
 914                        strbuf_add(payload, line, next - line);
 915                        in_signature = 0;
 916                }
 917                line = next;
 918        }
 919 cleanup:
 920        free(buffer);
 921        return saw_signature;
 922}
 923
 924static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
 925{
 926        struct merge_remote_desc *desc;
 927        struct commit_extra_header *mergetag;
 928        char *buf;
 929        unsigned long size, len;
 930        enum object_type type;
 931
 932        desc = merge_remote_util(parent);
 933        if (!desc || !desc->obj)
 934                return;
 935        buf = read_sha1_file(desc->obj->sha1, &type, &size);
 936        if (!buf || type != OBJ_TAG)
 937                goto free_return;
 938        len = parse_signature(buf, size);
 939        if (size == len)
 940                goto free_return;
 941        /*
 942         * We could verify this signature and either omit the tag when
 943         * it does not validate, but the integrator may not have the
 944         * public key of the signer of the tag he is merging, while a
 945         * later auditor may have it while auditing, so let's not run
 946         * verify-signed-buffer here for now...
 947         *
 948         * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
 949         *      warn("warning: signed tag unverified.");
 950         */
 951        mergetag = xcalloc(1, sizeof(*mergetag));
 952        mergetag->key = xstrdup("mergetag");
 953        mergetag->value = buf;
 954        mergetag->len = size;
 955
 956        **tail = mergetag;
 957        *tail = &mergetag->next;
 958        return;
 959
 960free_return:
 961        free(buf);
 962}
 963
 964void append_merge_tag_headers(struct commit_list *parents,
 965                              struct commit_extra_header ***tail)
 966{
 967        while (parents) {
 968                struct commit *parent = parents->item;
 969                handle_signed_tag(parent, tail);
 970                parents = parents->next;
 971        }
 972}
 973
 974static void add_extra_header(struct strbuf *buffer,
 975                             struct commit_extra_header *extra)
 976{
 977        strbuf_addstr(buffer, extra->key);
 978        if (extra->len)
 979                strbuf_add_lines(buffer, " ", extra->value, extra->len);
 980        else
 981                strbuf_addch(buffer, '\n');
 982}
 983
 984struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
 985                                                      const char **exclude)
 986{
 987        struct commit_extra_header *extra = NULL;
 988        unsigned long size;
 989        enum object_type type;
 990        char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
 991        if (buffer && type == OBJ_COMMIT)
 992                extra = read_commit_extra_header_lines(buffer, size, exclude);
 993        free(buffer);
 994        return extra;
 995}
 996
 997static inline int standard_header_field(const char *field, size_t len)
 998{
 999        return ((len == 4 && !memcmp(field, "tree ", 5)) ||
1000                (len == 6 && !memcmp(field, "parent ", 7)) ||
1001                (len == 6 && !memcmp(field, "author ", 7)) ||
1002                (len == 9 && !memcmp(field, "committer ", 10)) ||
1003                (len == 8 && !memcmp(field, "encoding ", 9)));
1004}
1005
1006static int excluded_header_field(const char *field, size_t len, const char **exclude)
1007{
1008        if (!exclude)
1009                return 0;
1010
1011        while (*exclude) {
1012                size_t xlen = strlen(*exclude);
1013                if (len == xlen &&
1014                    !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
1015                        return 1;
1016                exclude++;
1017        }
1018        return 0;
1019}
1020
1021struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size,
1022                                                           const char **exclude)
1023{
1024        struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
1025        const char *line, *next, *eof, *eob;
1026        struct strbuf buf = STRBUF_INIT;
1027
1028        for (line = buffer, eob = line + size;
1029             line < eob && *line != '\n';
1030             line = next) {
1031                next = memchr(line, '\n', eob - line);
1032                next = next ? next + 1 : eob;
1033                if (*line == ' ') {
1034                        /* continuation */
1035                        if (it)
1036                                strbuf_add(&buf, line + 1, next - (line + 1));
1037                        continue;
1038                }
1039                if (it)
1040                        it->value = strbuf_detach(&buf, &it->len);
1041                strbuf_reset(&buf);
1042                it = NULL;
1043
1044                eof = strchr(line, ' ');
1045                if (next <= eof)
1046                        eof = next;
1047
1048                if (standard_header_field(line, eof - line) ||
1049                    excluded_header_field(line, eof - line, exclude))
1050                        continue;
1051
1052                it = xcalloc(1, sizeof(*it));
1053                it->key = xmemdupz(line, eof-line);
1054                *tail = it;
1055                tail = &it->next;
1056                if (eof + 1 < next)
1057                        strbuf_add(&buf, eof + 1, next - (eof + 1));
1058        }
1059        if (it)
1060                it->value = strbuf_detach(&buf, &it->len);
1061        return extra;
1062}
1063
1064void free_commit_extra_headers(struct commit_extra_header *extra)
1065{
1066        while (extra) {
1067                struct commit_extra_header *next = extra->next;
1068                free(extra->key);
1069                free(extra->value);
1070                free(extra);
1071                extra = next;
1072        }
1073}
1074
1075int commit_tree(const struct strbuf *msg, unsigned char *tree,
1076                struct commit_list *parents, unsigned char *ret,
1077                const char *author, const char *sign_commit)
1078{
1079        struct commit_extra_header *extra = NULL, **tail = &extra;
1080        int result;
1081
1082        append_merge_tag_headers(parents, &tail);
1083        result = commit_tree_extended(msg, tree, parents, ret,
1084                                      author, sign_commit, extra);
1085        free_commit_extra_headers(extra);
1086        return result;
1087}
1088
1089static const char commit_utf8_warn[] =
1090"Warning: commit message does not conform to UTF-8.\n"
1091"You may want to amend it after fixing the message, or set the config\n"
1092"variable i18n.commitencoding to the encoding your project uses.\n";
1093
1094int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
1095                         struct commit_list *parents, unsigned char *ret,
1096                         const char *author, const char *sign_commit,
1097                         struct commit_extra_header *extra)
1098{
1099        int result;
1100        int encoding_is_utf8;
1101        struct strbuf buffer;
1102
1103        assert_sha1_type(tree, OBJ_TREE);
1104
1105        if (memchr(msg->buf, '\0', msg->len))
1106                return error("a NUL byte in commit log message not allowed.");
1107
1108        /* Not having i18n.commitencoding is the same as having utf-8 */
1109        encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
1110
1111        strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
1112        strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
1113
1114        /*
1115         * NOTE! This ordering means that the same exact tree merged with a
1116         * different order of parents will be a _different_ changeset even
1117         * if everything else stays the same.
1118         */
1119        while (parents) {
1120                struct commit_list *next = parents->next;
1121                struct commit *parent = parents->item;
1122
1123                strbuf_addf(&buffer, "parent %s\n",
1124                            sha1_to_hex(parent->object.sha1));
1125                free(parents);
1126                parents = next;
1127        }
1128
1129        /* Person/date information */
1130        if (!author)
1131                author = git_author_info(IDENT_ERROR_ON_NO_NAME);
1132        strbuf_addf(&buffer, "author %s\n", author);
1133        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
1134        if (!encoding_is_utf8)
1135                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
1136
1137        while (extra) {
1138                add_extra_header(&buffer, extra);
1139                extra = extra->next;
1140        }
1141        strbuf_addch(&buffer, '\n');
1142
1143        /* And add the comment */
1144        strbuf_addbuf(&buffer, msg);
1145
1146        /* And check the encoding */
1147        if (encoding_is_utf8 && !is_utf8(buffer.buf))
1148                fprintf(stderr, commit_utf8_warn);
1149
1150        if (sign_commit && do_sign_commit(&buffer, sign_commit))
1151                return -1;
1152
1153        result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
1154        strbuf_release(&buffer);
1155        return result;
1156}
1157
1158struct commit *get_merge_parent(const char *name)
1159{
1160        struct object *obj;
1161        struct commit *commit;
1162        unsigned char sha1[20];
1163        if (get_sha1(name, sha1))
1164                return NULL;
1165        obj = parse_object(sha1);
1166        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
1167        if (commit && !commit->util) {
1168                struct merge_remote_desc *desc;
1169                desc = xmalloc(sizeof(*desc));
1170                desc->obj = obj;
1171                desc->name = strdup(name);
1172                commit->util = desc;
1173        }
1174        return commit;
1175}