Andrew's git / gitweb.git / sha1_file.c
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sha1_file.con commit [PATCH] fetch.c: Remove some duplicated code in process() (5de0bff)
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 *
   6 * This handles basic git sha1 object files - packing, unpacking,
   7 * creation etc.
   8 */
   9#include <sys/types.h>
  10#include <dirent.h>
  11#include "cache.h"
  12#include "delta.h"
  13#include "pack.h"
  14
  15#ifndef O_NOATIME
  16#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  17#define O_NOATIME 01000000
  18#else
  19#define O_NOATIME 0
  20#endif
  21#endif
  22
  23static unsigned int sha1_file_open_flag = O_NOATIME;
  24
  25static unsigned hexval(char c)
  26{
  27        if (c >= '0' && c <= '9')
  28                return c - '0';
  29        if (c >= 'a' && c <= 'f')
  30                return c - 'a' + 10;
  31        if (c >= 'A' && c <= 'F')
  32                return c - 'A' + 10;
  33        return ~0;
  34}
  35
  36int get_sha1_hex(const char *hex, unsigned char *sha1)
  37{
  38        int i;
  39        for (i = 0; i < 20; i++) {
  40                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  41                if (val & ~0xff)
  42                        return -1;
  43                *sha1++ = val;
  44                hex += 2;
  45        }
  46        return 0;
  47}
  48
  49static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir,
  50        *git_graft_file;
  51static void setup_git_env(void)
  52{
  53        git_dir = getenv(GIT_DIR_ENVIRONMENT);
  54        if (!git_dir)
  55                git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
  56        git_object_dir = getenv(DB_ENVIRONMENT);
  57        if (!git_object_dir) {
  58                git_object_dir = xmalloc(strlen(git_dir) + 9);
  59                sprintf(git_object_dir, "%s/objects", git_dir);
  60        }
  61        git_refs_dir = xmalloc(strlen(git_dir) + 6);
  62        sprintf(git_refs_dir, "%s/refs", git_dir);
  63        git_index_file = getenv(INDEX_ENVIRONMENT);
  64        if (!git_index_file) {
  65                git_index_file = xmalloc(strlen(git_dir) + 7);
  66                sprintf(git_index_file, "%s/index", git_dir);
  67        }
  68        git_graft_file = getenv(GRAFT_ENVIRONMENT);
  69        if (!git_graft_file)
  70                git_graft_file = strdup(git_path("info/grafts"));
  71}
  72
  73char *get_object_directory(void)
  74{
  75        if (!git_object_dir)
  76                setup_git_env();
  77        return git_object_dir;
  78}
  79
  80char *get_refs_directory(void)
  81{
  82        if (!git_refs_dir)
  83                setup_git_env();
  84        return git_refs_dir;
  85}
  86
  87char *get_index_file(void)
  88{
  89        if (!git_index_file)
  90                setup_git_env();
  91        return git_index_file;
  92}
  93
  94char *get_graft_file(void)
  95{
  96        if (!git_graft_file)
  97                setup_git_env();
  98        return git_graft_file;
  99}
 100
 101int safe_create_leading_directories(char *path)
 102{
 103        char *pos = path;
 104
 105        while (pos) {
 106                pos = strchr(pos, '/');
 107                if (!pos)
 108                        break;
 109                *pos = 0;
 110                if (mkdir(path, 0777) < 0)
 111                        if (errno != EEXIST) {
 112                                *pos = '/';
 113                                return -1;
 114                        }
 115                *pos++ = '/';
 116        }
 117        return 0;
 118}
 119
 120char * sha1_to_hex(const unsigned char *sha1)
 121{
 122        static char buffer[50];
 123        static const char hex[] = "0123456789abcdef";
 124        char *buf = buffer;
 125        int i;
 126
 127        for (i = 0; i < 20; i++) {
 128                unsigned int val = *sha1++;
 129                *buf++ = hex[val >> 4];
 130                *buf++ = hex[val & 0xf];
 131        }
 132        return buffer;
 133}
 134
 135static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 136{
 137        int i;
 138        for (i = 0; i < 20; i++) {
 139                static char hex[] = "0123456789abcdef";
 140                unsigned int val = sha1[i];
 141                char *pos = pathbuf + i*2 + (i > 0);
 142                *pos++ = hex[val >> 4];
 143                *pos = hex[val & 0xf];
 144        }
 145}
 146
 147/*
 148 * NOTE! This returns a statically allocated buffer, so you have to be
 149 * careful about using it. Do a "strdup()" if you need to save the
 150 * filename.
 151 *
 152 * Also note that this returns the location for creating.  Reading
 153 * SHA1 file can happen from any alternate directory listed in the
 154 * DB_ENVIRONMENT environment variable if it is not found in
 155 * the primary object database.
 156 */
 157char *sha1_file_name(const unsigned char *sha1)
 158{
 159        static char *name, *base;
 160
 161        if (!base) {
 162                const char *sha1_file_directory = get_object_directory();
 163                int len = strlen(sha1_file_directory);
 164                base = xmalloc(len + 60);
 165                memcpy(base, sha1_file_directory, len);
 166                memset(base+len, 0, 60);
 167                base[len] = '/';
 168                base[len+3] = '/';
 169                name = base + len + 1;
 170        }
 171        fill_sha1_path(name, sha1);
 172        return base;
 173}
 174
 175char *sha1_pack_name(const unsigned char *sha1)
 176{
 177        static const char hex[] = "0123456789abcdef";
 178        static char *name, *base, *buf;
 179        int i;
 180
 181        if (!base) {
 182                const char *sha1_file_directory = get_object_directory();
 183                int len = strlen(sha1_file_directory);
 184                base = xmalloc(len + 60);
 185                sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 186                name = base + len + 11;
 187        }
 188
 189        buf = name;
 190
 191        for (i = 0; i < 20; i++) {
 192                unsigned int val = *sha1++;
 193                *buf++ = hex[val >> 4];
 194                *buf++ = hex[val & 0xf];
 195        }
 196        
 197        return base;
 198}
 199
 200char *sha1_pack_index_name(const unsigned char *sha1)
 201{
 202        static const char hex[] = "0123456789abcdef";
 203        static char *name, *base, *buf;
 204        int i;
 205
 206        if (!base) {
 207                const char *sha1_file_directory = get_object_directory();
 208                int len = strlen(sha1_file_directory);
 209                base = xmalloc(len + 60);
 210                sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 211                name = base + len + 11;
 212        }
 213
 214        buf = name;
 215
 216        for (i = 0; i < 20; i++) {
 217                unsigned int val = *sha1++;
 218                *buf++ = hex[val >> 4];
 219                *buf++ = hex[val & 0xf];
 220        }
 221        
 222        return base;
 223}
 224
 225struct alternate_object_database *alt_odb_list;
 226static struct alternate_object_database **alt_odb_tail;
 227
 228/*
 229 * Prepare alternate object database registry.
 230 *
 231 * The variable alt_odb_list points at the list of struct
 232 * alternate_object_database.  The elements on this list come from
 233 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 234 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 235 * whose contents is exactly in the same format as that environment
 236 * variable.  Its base points at a statically allocated buffer that
 237 * contains "/the/directory/corresponding/to/.git/objects/...", while
 238 * its name points just after the slash at the end of ".git/objects/"
 239 * in the example above, and has enough space to hold 40-byte hex
 240 * SHA1, an extra slash for the first level indirection, and the
 241 * terminating NUL.
 242 */
 243static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 244                                 const char *relative_base)
 245{
 246        const char *cp, *last;
 247        struct alternate_object_database *ent;
 248        int base_len = -1;
 249
 250        last = alt;
 251        while (last < ep) {
 252                cp = last;
 253                if (cp < ep && *cp == '#') {
 254                        while (cp < ep && *cp != sep)
 255                                cp++;
 256                        last = cp + 1;
 257                        continue;
 258                }
 259                for ( ; cp < ep && *cp != sep; cp++)
 260                        ;
 261                if (last != cp) {
 262                        /* 43 = 40-byte + 2 '/' + terminating NUL */
 263                        int pfxlen = cp - last;
 264                        int entlen = pfxlen + 43;
 265
 266                        if (*last != '/' && relative_base) {
 267                                /* Relative alt-odb */
 268                                if (base_len < 0)
 269                                        base_len = strlen(relative_base) + 1;
 270                                entlen += base_len;
 271                                pfxlen += base_len;
 272                        }
 273                        ent = xmalloc(sizeof(*ent) + entlen);
 274                        *alt_odb_tail = ent;
 275                        alt_odb_tail = &(ent->next);
 276                        ent->next = NULL;
 277                        if (*last != '/' && relative_base) {
 278                                memcpy(ent->base, relative_base, base_len - 1);
 279                                ent->base[base_len - 1] = '/';
 280                                memcpy(ent->base + base_len,
 281                                       last, cp - last);
 282                        }
 283                        else
 284                                memcpy(ent->base, last, pfxlen);
 285                        ent->name = ent->base + pfxlen + 1;
 286                        ent->base[pfxlen] = ent->base[pfxlen + 3] = '/';
 287                        ent->base[entlen-1] = 0;
 288                }
 289                while (cp < ep && *cp == sep)
 290                        cp++;
 291                last = cp;
 292        }
 293}
 294
 295void prepare_alt_odb(void)
 296{
 297        char path[PATH_MAX];
 298        char *map;
 299        int fd;
 300        struct stat st;
 301        char *alt;
 302
 303        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 304        if (!alt) alt = "";
 305
 306        if (alt_odb_tail)
 307                return;
 308        alt_odb_tail = &alt_odb_list;
 309        link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL);
 310
 311        sprintf(path, "%s/info/alternates", get_object_directory());
 312        fd = open(path, O_RDONLY);
 313        if (fd < 0)
 314                return;
 315        if (fstat(fd, &st) || (st.st_size == 0)) {
 316                close(fd);
 317                return;
 318        }
 319        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 320        close(fd);
 321        if (map == MAP_FAILED)
 322                return;
 323
 324        link_alt_odb_entries(map, map + st.st_size, '\n',
 325                             get_object_directory());
 326        munmap(map, st.st_size);
 327}
 328
 329static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 330{
 331        char *name = sha1_file_name(sha1);
 332        struct alternate_object_database *alt;
 333
 334        if (!stat(name, st))
 335                return name;
 336        prepare_alt_odb();
 337        for (alt = alt_odb_list; alt; alt = alt->next) {
 338                name = alt->name;
 339                fill_sha1_path(name, sha1);
 340                if (!stat(alt->base, st))
 341                        return alt->base;
 342        }
 343        return NULL;
 344}
 345
 346#define PACK_MAX_SZ (1<<26)
 347static int pack_used_ctr;
 348static unsigned long pack_mapped;
 349struct packed_git *packed_git;
 350
 351static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 352                                void **idx_map_)
 353{
 354        void *idx_map;
 355        unsigned int *index;
 356        unsigned long idx_size;
 357        int nr, i;
 358        int fd = open(path, O_RDONLY);
 359        struct stat st;
 360        if (fd < 0)
 361                return -1;
 362        if (fstat(fd, &st)) {
 363                close(fd);
 364                return -1;
 365        }
 366        idx_size = st.st_size;
 367        idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 368        close(fd);
 369        if (idx_map == MAP_FAILED)
 370                return -1;
 371
 372        index = idx_map;
 373        *idx_map_ = idx_map;
 374        *idx_size_ = idx_size;
 375
 376        /* check index map */
 377        if (idx_size < 4*256 + 20 + 20)
 378                return error("index file too small");
 379        nr = 0;
 380        for (i = 0; i < 256; i++) {
 381                unsigned int n = ntohl(index[i]);
 382                if (n < nr)
 383                        return error("non-monotonic index");
 384                nr = n;
 385        }
 386
 387        /*
 388         * Total size:
 389         *  - 256 index entries 4 bytes each
 390         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 391         *  - 20-byte SHA1 of the packfile
 392         *  - 20-byte SHA1 file checksum
 393         */
 394        if (idx_size != 4*256 + nr * 24 + 20 + 20)
 395                return error("wrong index file size");
 396
 397        return 0;
 398}
 399
 400static int unuse_one_packed_git(void)
 401{
 402        struct packed_git *p, *lru = NULL;
 403
 404        for (p = packed_git; p; p = p->next) {
 405                if (p->pack_use_cnt || !p->pack_base)
 406                        continue;
 407                if (!lru || p->pack_last_used < lru->pack_last_used)
 408                        lru = p;
 409        }
 410        if (!lru)
 411                return 0;
 412        munmap(lru->pack_base, lru->pack_size);
 413        lru->pack_base = NULL;
 414        return 1;
 415}
 416
 417void unuse_packed_git(struct packed_git *p)
 418{
 419        p->pack_use_cnt--;
 420}
 421
 422int use_packed_git(struct packed_git *p)
 423{
 424        if (!p->pack_size) {
 425                struct stat st;
 426                // We created the struct before we had the pack
 427                stat(p->pack_name, &st);
 428                if (!S_ISREG(st.st_mode))
 429                        die("packfile %s not a regular file", p->pack_name);
 430                p->pack_size = st.st_size;
 431        }
 432        if (!p->pack_base) {
 433                int fd;
 434                struct stat st;
 435                void *map;
 436
 437                pack_mapped += p->pack_size;
 438                while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 439                        ; /* nothing */
 440                fd = open(p->pack_name, O_RDONLY);
 441                if (fd < 0)
 442                        die("packfile %s cannot be opened", p->pack_name);
 443                if (fstat(fd, &st)) {
 444                        close(fd);
 445                        die("packfile %s cannot be opened", p->pack_name);
 446                }
 447                if (st.st_size != p->pack_size)
 448                        die("packfile %s size mismatch.", p->pack_name);
 449                map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 450                close(fd);
 451                if (map == MAP_FAILED)
 452                        die("packfile %s cannot be mapped.", p->pack_name);
 453                p->pack_base = map;
 454
 455                /* Check if the pack file matches with the index file.
 456                 * this is cheap.
 457                 */
 458                if (memcmp((char*)(p->index_base) + p->index_size - 40,
 459                           p->pack_base + p->pack_size - 20, 20)) {
 460                              
 461                        die("packfile %s does not match index.", p->pack_name);
 462                }
 463        }
 464        p->pack_last_used = pack_used_ctr++;
 465        p->pack_use_cnt++;
 466        return 0;
 467}
 468
 469struct packed_git *add_packed_git(char *path, int path_len)
 470{
 471        struct stat st;
 472        struct packed_git *p;
 473        unsigned long idx_size;
 474        void *idx_map;
 475
 476        if (check_packed_git_idx(path, &idx_size, &idx_map))
 477                return NULL;
 478
 479        /* do we have a corresponding .pack file? */
 480        strcpy(path + path_len - 4, ".pack");
 481        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 482                munmap(idx_map, idx_size);
 483                return NULL;
 484        }
 485        /* ok, it looks sane as far as we can check without
 486         * actually mapping the pack file.
 487         */
 488        p = xmalloc(sizeof(*p) + path_len + 2);
 489        strcpy(p->pack_name, path);
 490        p->index_size = idx_size;
 491        p->pack_size = st.st_size;
 492        p->index_base = idx_map;
 493        p->next = NULL;
 494        p->pack_base = NULL;
 495        p->pack_last_used = 0;
 496        p->pack_use_cnt = 0;
 497        return p;
 498}
 499
 500struct packed_git *parse_pack_index(unsigned char *sha1)
 501{
 502        char *path = sha1_pack_index_name(sha1);
 503        return parse_pack_index_file(sha1, path);
 504}
 505
 506struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 507{
 508        struct packed_git *p;
 509        unsigned long idx_size;
 510        void *idx_map;
 511        char *path;
 512
 513        if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 514                return NULL;
 515
 516        path = sha1_pack_name(sha1);
 517
 518        p = xmalloc(sizeof(*p) + strlen(path) + 2);
 519        strcpy(p->pack_name, path);
 520        p->index_size = idx_size;
 521        p->pack_size = 0;
 522        p->index_base = idx_map;
 523        p->next = NULL;
 524        p->pack_base = NULL;
 525        p->pack_last_used = 0;
 526        p->pack_use_cnt = 0;
 527        memcpy(p->sha1, sha1, 20);
 528        return p;
 529}
 530
 531void install_packed_git(struct packed_git *pack)
 532{
 533        pack->next = packed_git;
 534        packed_git = pack;
 535}
 536
 537static void prepare_packed_git_one(char *objdir)
 538{
 539        char path[PATH_MAX];
 540        int len;
 541        DIR *dir;
 542        struct dirent *de;
 543
 544        sprintf(path, "%s/pack", objdir);
 545        len = strlen(path);
 546        dir = opendir(path);
 547        if (!dir)
 548                return;
 549        path[len++] = '/';
 550        while ((de = readdir(dir)) != NULL) {
 551                int namelen = strlen(de->d_name);
 552                struct packed_git *p;
 553
 554                if (strcmp(de->d_name + namelen - 4, ".idx"))
 555                        continue;
 556
 557                /* we have .idx.  Is it a file we can map? */
 558                strcpy(path + len, de->d_name);
 559                p = add_packed_git(path, len + namelen);
 560                if (!p)
 561                        continue;
 562                p->next = packed_git;
 563                packed_git = p;
 564        }
 565        closedir(dir);
 566}
 567
 568void prepare_packed_git(void)
 569{
 570        static int run_once = 0;
 571        struct alternate_object_database *alt;
 572
 573        if (run_once)
 574                return;
 575        prepare_packed_git_one(get_object_directory());
 576        prepare_alt_odb();
 577        for (alt = alt_odb_list; alt; alt = alt->next) {
 578                alt->name[0] = 0;
 579                prepare_packed_git_one(alt->base);
 580        }
 581        run_once = 1;
 582}
 583
 584int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 585{
 586        char header[100];
 587        unsigned char real_sha1[20];
 588        SHA_CTX c;
 589
 590        SHA1_Init(&c);
 591        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 592        SHA1_Update(&c, map, size);
 593        SHA1_Final(real_sha1, &c);
 594        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 595}
 596
 597static void *map_sha1_file_internal(const unsigned char *sha1,
 598                                    unsigned long *size)
 599{
 600        struct stat st;
 601        void *map;
 602        int fd;
 603        char *filename = find_sha1_file(sha1, &st);
 604
 605        if (!filename) {
 606                return NULL;
 607        }
 608
 609        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 610        if (fd < 0) {
 611                /* See if it works without O_NOATIME */
 612                switch (sha1_file_open_flag) {
 613                default:
 614                        fd = open(filename, O_RDONLY);
 615                        if (fd >= 0)
 616                                break;
 617                /* Fallthrough */
 618                case 0:
 619                        return NULL;
 620                }
 621
 622                /* If it failed once, it will probably fail again.
 623                 * Stop using O_NOATIME
 624                 */
 625                sha1_file_open_flag = 0;
 626        }
 627        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 628        close(fd);
 629        if (map == MAP_FAILED)
 630                return NULL;
 631        *size = st.st_size;
 632        return map;
 633}
 634
 635int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 636{
 637        /* Get the data stream */
 638        memset(stream, 0, sizeof(*stream));
 639        stream->next_in = map;
 640        stream->avail_in = mapsize;
 641        stream->next_out = buffer;
 642        stream->avail_out = size;
 643
 644        inflateInit(stream);
 645        return inflate(stream, 0);
 646}
 647
 648static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 649{
 650        int bytes = strlen(buffer) + 1;
 651        unsigned char *buf = xmalloc(1+size);
 652
 653        memcpy(buf, buffer + bytes, stream->total_out - bytes);
 654        bytes = stream->total_out - bytes;
 655        if (bytes < size) {
 656                stream->next_out = buf + bytes;
 657                stream->avail_out = size - bytes;
 658                while (inflate(stream, Z_FINISH) == Z_OK)
 659                        /* nothing */;
 660        }
 661        buf[size] = 0;
 662        inflateEnd(stream);
 663        return buf;
 664}
 665
 666/*
 667 * We used to just use "sscanf()", but that's actually way
 668 * too permissive for what we want to check. So do an anal
 669 * object header parse by hand.
 670 */
 671int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 672{
 673        int i;
 674        unsigned long size;
 675
 676        /*
 677         * The type can be at most ten bytes (including the 
 678         * terminating '\0' that we add), and is followed by
 679         * a space. 
 680         */
 681        i = 10;
 682        for (;;) {
 683                char c = *hdr++;
 684                if (c == ' ')
 685                        break;
 686                if (!--i)
 687                        return -1;
 688                *type++ = c;
 689        }
 690        *type = 0;
 691
 692        /*
 693         * The length must follow immediately, and be in canonical
 694         * decimal format (ie "010" is not valid).
 695         */
 696        size = *hdr++ - '0';
 697        if (size > 9)
 698                return -1;
 699        if (size) {
 700                for (;;) {
 701                        unsigned long c = *hdr - '0';
 702                        if (c > 9)
 703                                break;
 704                        hdr++;
 705                        size = size * 10 + c;
 706                }
 707        }
 708        *sizep = size;
 709
 710        /*
 711         * The length must be followed by a zero byte
 712         */
 713        return *hdr ? -1 : 0;
 714}
 715
 716void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 717{
 718        int ret;
 719        z_stream stream;
 720        char hdr[8192];
 721
 722        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 723        if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 724                return NULL;
 725
 726        return unpack_sha1_rest(&stream, hdr, *size);
 727}
 728
 729/* forward declaration for a mutually recursive function */
 730static int packed_object_info(struct pack_entry *entry,
 731                              char *type, unsigned long *sizep);
 732
 733static int packed_delta_info(unsigned char *base_sha1,
 734                             unsigned long delta_size,
 735                             unsigned long left,
 736                             char *type,
 737                             unsigned long *sizep,
 738                             struct packed_git *p)
 739{
 740        struct pack_entry base_ent;
 741
 742        if (left < 20)
 743                die("truncated pack file");
 744
 745        /* The base entry _must_ be in the same pack */
 746        if (!find_pack_entry_one(base_sha1, &base_ent, p))
 747                die("failed to find delta-pack base object %s",
 748                    sha1_to_hex(base_sha1));
 749
 750        /* We choose to only get the type of the base object and
 751         * ignore potentially corrupt pack file that expects the delta
 752         * based on a base with a wrong size.  This saves tons of
 753         * inflate() calls.
 754         */
 755
 756        if (packed_object_info(&base_ent, type, NULL))
 757                die("cannot get info for delta-pack base");
 758
 759        if (sizep) {
 760                const unsigned char *data;
 761                unsigned char delta_head[64];
 762                unsigned long result_size;
 763                z_stream stream;
 764                int st;
 765
 766                memset(&stream, 0, sizeof(stream));
 767
 768                data = stream.next_in = base_sha1 + 20;
 769                stream.avail_in = left - 20;
 770                stream.next_out = delta_head;
 771                stream.avail_out = sizeof(delta_head);
 772
 773                inflateInit(&stream);
 774                st = inflate(&stream, Z_FINISH);
 775                inflateEnd(&stream);
 776                if ((st != Z_STREAM_END) &&
 777                    stream.total_out != sizeof(delta_head))
 778                        die("delta data unpack-initial failed");
 779
 780                /* Examine the initial part of the delta to figure out
 781                 * the result size.
 782                 */
 783                data = delta_head;
 784                get_delta_hdr_size(&data); /* ignore base size */
 785
 786                /* Read the result size */
 787                result_size = get_delta_hdr_size(&data);
 788                *sizep = result_size;
 789        }
 790        return 0;
 791}
 792
 793static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 794        enum object_type *type, unsigned long *sizep)
 795{
 796        unsigned shift;
 797        unsigned char *pack, c;
 798        unsigned long size;
 799
 800        if (offset >= p->pack_size)
 801                die("object offset outside of pack file");
 802
 803        pack =  p->pack_base + offset;
 804        c = *pack++;
 805        offset++;
 806        *type = (c >> 4) & 7;
 807        size = c & 15;
 808        shift = 4;
 809        while (c & 0x80) {
 810                if (offset >= p->pack_size)
 811                        die("object offset outside of pack file");
 812                c = *pack++;
 813                offset++;
 814                size += (c & 0x7f) << shift;
 815                shift += 7;
 816        }
 817        *sizep = size;
 818        return offset;
 819}
 820
 821void packed_object_info_detail(struct pack_entry *e,
 822                               char *type,
 823                               unsigned long *size,
 824                               unsigned long *store_size,
 825                               int *delta_chain_length,
 826                               unsigned char *base_sha1)
 827{
 828        struct packed_git *p = e->p;
 829        unsigned long offset, left;
 830        unsigned char *pack;
 831        enum object_type kind;
 832
 833        offset = unpack_object_header(p, e->offset, &kind, size);
 834        pack = p->pack_base + offset;
 835        left = p->pack_size - offset;
 836        if (kind != OBJ_DELTA)
 837                *delta_chain_length = 0;
 838        else {
 839                int chain_length = 0;
 840                memcpy(base_sha1, pack, 20);
 841                do {
 842                        struct pack_entry base_ent;
 843                        unsigned long junk;
 844
 845                        find_pack_entry_one(pack, &base_ent, p);
 846                        offset = unpack_object_header(p, base_ent.offset,
 847                                                      &kind, &junk);
 848                        pack = p->pack_base + offset;
 849                        chain_length++;
 850                } while (kind == OBJ_DELTA);
 851                *delta_chain_length = chain_length;
 852        }
 853        switch (kind) {
 854        case OBJ_COMMIT:
 855                strcpy(type, "commit");
 856                break;
 857        case OBJ_TREE:
 858                strcpy(type, "tree");
 859                break;
 860        case OBJ_BLOB:
 861                strcpy(type, "blob");
 862                break;
 863        case OBJ_TAG:
 864                strcpy(type, "tag");
 865                break;
 866        default:
 867                die("corrupted pack file");
 868        }
 869        *store_size = 0; /* notyet */
 870}
 871
 872static int packed_object_info(struct pack_entry *entry,
 873                              char *type, unsigned long *sizep)
 874{
 875        struct packed_git *p = entry->p;
 876        unsigned long offset, size, left;
 877        unsigned char *pack;
 878        enum object_type kind;
 879        int retval;
 880
 881        if (use_packed_git(p))
 882                die("cannot map packed file");
 883
 884        offset = unpack_object_header(p, entry->offset, &kind, &size);
 885        pack = p->pack_base + offset;
 886        left = p->pack_size - offset;
 887
 888        switch (kind) {
 889        case OBJ_DELTA:
 890                retval = packed_delta_info(pack, size, left, type, sizep, p);
 891                unuse_packed_git(p);
 892                return retval;
 893        case OBJ_COMMIT:
 894                strcpy(type, "commit");
 895                break;
 896        case OBJ_TREE:
 897                strcpy(type, "tree");
 898                break;
 899        case OBJ_BLOB:
 900                strcpy(type, "blob");
 901                break;
 902        case OBJ_TAG:
 903                strcpy(type, "tag");
 904                break;
 905        default:
 906                die("corrupted pack file");
 907        }
 908        if (sizep)
 909                *sizep = size;
 910        unuse_packed_git(p);
 911        return 0;
 912}
 913
 914/* forward declaration for a mutually recursive function */
 915static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 916
 917static void *unpack_delta_entry(unsigned char *base_sha1,
 918                                unsigned long delta_size,
 919                                unsigned long left,
 920                                char *type,
 921                                unsigned long *sizep,
 922                                struct packed_git *p)
 923{
 924        struct pack_entry base_ent;
 925        void *data, *delta_data, *result, *base;
 926        unsigned long data_size, result_size, base_size;
 927        z_stream stream;
 928        int st;
 929
 930        if (left < 20)
 931                die("truncated pack file");
 932        data = base_sha1 + 20;
 933        data_size = left - 20;
 934        delta_data = xmalloc(delta_size);
 935
 936        memset(&stream, 0, sizeof(stream));
 937
 938        stream.next_in = data;
 939        stream.avail_in = data_size;
 940        stream.next_out = delta_data;
 941        stream.avail_out = delta_size;
 942
 943        inflateInit(&stream);
 944        st = inflate(&stream, Z_FINISH);
 945        inflateEnd(&stream);
 946        if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 947                die("delta data unpack failed");
 948
 949        /* The base entry _must_ be in the same pack */
 950        if (!find_pack_entry_one(base_sha1, &base_ent, p))
 951                die("failed to find delta-pack base object %s",
 952                    sha1_to_hex(base_sha1));
 953        base = unpack_entry_gently(&base_ent, type, &base_size);
 954        if (!base)
 955                die("failed to read delta-pack base object %s",
 956                    sha1_to_hex(base_sha1));
 957        result = patch_delta(base, base_size,
 958                             delta_data, delta_size,
 959                             &result_size);
 960        if (!result)
 961                die("failed to apply delta");
 962        free(delta_data);
 963        free(base);
 964        *sizep = result_size;
 965        return result;
 966}
 967
 968static void *unpack_non_delta_entry(unsigned char *data,
 969                                    unsigned long size,
 970                                    unsigned long left)
 971{
 972        int st;
 973        z_stream stream;
 974        unsigned char *buffer;
 975
 976        buffer = xmalloc(size + 1);
 977        buffer[size] = 0;
 978        memset(&stream, 0, sizeof(stream));
 979        stream.next_in = data;
 980        stream.avail_in = left;
 981        stream.next_out = buffer;
 982        stream.avail_out = size;
 983
 984        inflateInit(&stream);
 985        st = inflate(&stream, Z_FINISH);
 986        inflateEnd(&stream);
 987        if ((st != Z_STREAM_END) || stream.total_out != size) {
 988                free(buffer);
 989                return NULL;
 990        }
 991
 992        return buffer;
 993}
 994
 995static void *unpack_entry(struct pack_entry *entry,
 996                          char *type, unsigned long *sizep)
 997{
 998        struct packed_git *p = entry->p;
 999        void *retval;
1000
1001        if (use_packed_git(p))
1002                die("cannot map packed file");
1003        retval = unpack_entry_gently(entry, type, sizep);
1004        unuse_packed_git(p);
1005        if (!retval)
1006                die("corrupted pack file");
1007        return retval;
1008}
1009
1010/* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1011void *unpack_entry_gently(struct pack_entry *entry,
1012                          char *type, unsigned long *sizep)
1013{
1014        struct packed_git *p = entry->p;
1015        unsigned long offset, size, left;
1016        unsigned char *pack;
1017        enum object_type kind;
1018        void *retval;
1019
1020        offset = unpack_object_header(p, entry->offset, &kind, &size);
1021        pack = p->pack_base + offset;
1022        left = p->pack_size - offset;
1023        switch (kind) {
1024        case OBJ_DELTA:
1025                retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1026                return retval;
1027        case OBJ_COMMIT:
1028                strcpy(type, "commit");
1029                break;
1030        case OBJ_TREE:
1031                strcpy(type, "tree");
1032                break;
1033        case OBJ_BLOB:
1034                strcpy(type, "blob");
1035                break;
1036        case OBJ_TAG:
1037                strcpy(type, "tag");
1038                break;
1039        default:
1040                return NULL;
1041        }
1042        *sizep = size;
1043        retval = unpack_non_delta_entry(pack, size, left);
1044        return retval;
1045}
1046
1047int num_packed_objects(const struct packed_git *p)
1048{
1049        /* See check_packed_git_idx() */
1050        return (p->index_size - 20 - 20 - 4*256) / 24;
1051}
1052
1053int nth_packed_object_sha1(const struct packed_git *p, int n,
1054                           unsigned char* sha1)
1055{
1056        void *index = p->index_base + 256;
1057        if (n < 0 || num_packed_objects(p) <= n)
1058                return -1;
1059        memcpy(sha1, (index + 24 * n + 4), 20);
1060        return 0;
1061}
1062
1063int find_pack_entry_one(const unsigned char *sha1,
1064                        struct pack_entry *e, struct packed_git *p)
1065{
1066        unsigned int *level1_ofs = p->index_base;
1067        int hi = ntohl(level1_ofs[*sha1]);
1068        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1069        void *index = p->index_base + 256;
1070
1071        do {
1072                int mi = (lo + hi) / 2;
1073                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1074                if (!cmp) {
1075                        e->offset = ntohl(*((int*)(index + 24 * mi)));
1076                        memcpy(e->sha1, sha1, 20);
1077                        e->p = p;
1078                        return 1;
1079                }
1080                if (cmp > 0)
1081                        hi = mi;
1082                else
1083                        lo = mi+1;
1084        } while (lo < hi);
1085        return 0;
1086}
1087
1088static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1089{
1090        struct packed_git *p;
1091        prepare_packed_git();
1092
1093        for (p = packed_git; p; p = p->next) {
1094                if (find_pack_entry_one(sha1, e, p))
1095                        return 1;
1096        }
1097        return 0;
1098}
1099
1100struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1101                                  struct packed_git *packs)
1102{
1103        struct packed_git *p;
1104        struct pack_entry e;
1105
1106        for (p = packs; p; p = p->next) {
1107                if (find_pack_entry_one(sha1, &e, p))
1108                        return p;
1109        }
1110        return NULL;
1111        
1112}
1113
1114int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1115{
1116        int status;
1117        unsigned long mapsize, size;
1118        void *map;
1119        z_stream stream;
1120        char hdr[128];
1121
1122        map = map_sha1_file_internal(sha1, &mapsize);
1123        if (!map) {
1124                struct pack_entry e;
1125
1126                if (!find_pack_entry(sha1, &e))
1127                        return error("unable to find %s", sha1_to_hex(sha1));
1128                return packed_object_info(&e, type, sizep);
1129        }
1130        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1131                status = error("unable to unpack %s header",
1132                               sha1_to_hex(sha1));
1133        if (parse_sha1_header(hdr, type, &size) < 0)
1134                status = error("unable to parse %s header", sha1_to_hex(sha1));
1135        else {
1136                status = 0;
1137                if (sizep)
1138                        *sizep = size;
1139        }
1140        inflateEnd(&stream);
1141        munmap(map, mapsize);
1142        return status;
1143}
1144
1145static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1146{
1147        struct pack_entry e;
1148
1149        if (!find_pack_entry(sha1, &e)) {
1150                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1151                return NULL;
1152        }
1153        return unpack_entry(&e, type, size);
1154}
1155
1156void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1157{
1158        unsigned long mapsize;
1159        void *map, *buf;
1160        struct pack_entry e;
1161
1162        if (find_pack_entry(sha1, &e))
1163                return read_packed_sha1(sha1, type, size);
1164        map = map_sha1_file_internal(sha1, &mapsize);
1165        if (map) {
1166                buf = unpack_sha1_file(map, mapsize, type, size);
1167                munmap(map, mapsize);
1168                return buf;
1169        }
1170        return NULL;
1171}
1172
1173void *read_object_with_reference(const unsigned char *sha1,
1174                                 const char *required_type,
1175                                 unsigned long *size,
1176                                 unsigned char *actual_sha1_return)
1177{
1178        char type[20];
1179        void *buffer;
1180        unsigned long isize;
1181        unsigned char actual_sha1[20];
1182
1183        memcpy(actual_sha1, sha1, 20);
1184        while (1) {
1185                int ref_length = -1;
1186                const char *ref_type = NULL;
1187
1188                buffer = read_sha1_file(actual_sha1, type, &isize);
1189                if (!buffer)
1190                        return NULL;
1191                if (!strcmp(type, required_type)) {
1192                        *size = isize;
1193                        if (actual_sha1_return)
1194                                memcpy(actual_sha1_return, actual_sha1, 20);
1195                        return buffer;
1196                }
1197                /* Handle references */
1198                else if (!strcmp(type, "commit"))
1199                        ref_type = "tree ";
1200                else if (!strcmp(type, "tag"))
1201                        ref_type = "object ";
1202                else {
1203                        free(buffer);
1204                        return NULL;
1205                }
1206                ref_length = strlen(ref_type);
1207
1208                if (memcmp(buffer, ref_type, ref_length) ||
1209                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
1210                        free(buffer);
1211                        return NULL;
1212                }
1213                free(buffer);
1214                /* Now we have the ID of the referred-to object in
1215                 * actual_sha1.  Check again. */
1216        }
1217}
1218
1219char *write_sha1_file_prepare(void *buf,
1220                              unsigned long len,
1221                              const char *type,
1222                              unsigned char *sha1,
1223                              unsigned char *hdr,
1224                              int *hdrlen)
1225{
1226        SHA_CTX c;
1227
1228        /* Generate the header */
1229        *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1230
1231        /* Sha1.. */
1232        SHA1_Init(&c);
1233        SHA1_Update(&c, hdr, *hdrlen);
1234        SHA1_Update(&c, buf, len);
1235        SHA1_Final(sha1, &c);
1236
1237        return sha1_file_name(sha1);
1238}
1239
1240int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1241{
1242        int size;
1243        unsigned char *compressed;
1244        z_stream stream;
1245        unsigned char sha1[20];
1246        char *filename;
1247        static char tmpfile[PATH_MAX];
1248        unsigned char hdr[50];
1249        int fd, hdrlen, ret;
1250
1251        /* Normally if we have it in the pack then we do not bother writing
1252         * it out into .git/objects/??/?{38} file.
1253         */
1254        filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1255        if (returnsha1)
1256                memcpy(returnsha1, sha1, 20);
1257        if (has_sha1_file(sha1))
1258                return 0;
1259        fd = open(filename, O_RDONLY);
1260        if (fd >= 0) {
1261                /*
1262                 * FIXME!!! We might do collision checking here, but we'd
1263                 * need to uncompress the old file and check it. Later.
1264                 */
1265                close(fd);
1266                return 0;
1267        }
1268
1269        if (errno != ENOENT) {
1270                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1271                return -1;
1272        }
1273
1274        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1275
1276        fd = mkstemp(tmpfile);
1277        if (fd < 0) {
1278                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1279                return -1;
1280        }
1281
1282        /* Set it up */
1283        memset(&stream, 0, sizeof(stream));
1284        deflateInit(&stream, Z_BEST_COMPRESSION);
1285        size = deflateBound(&stream, len+hdrlen);
1286        compressed = xmalloc(size);
1287
1288        /* Compress it */
1289        stream.next_out = compressed;
1290        stream.avail_out = size;
1291
1292        /* First header.. */
1293        stream.next_in = hdr;
1294        stream.avail_in = hdrlen;
1295        while (deflate(&stream, 0) == Z_OK)
1296                /* nothing */;
1297
1298        /* Then the data itself.. */
1299        stream.next_in = buf;
1300        stream.avail_in = len;
1301        while (deflate(&stream, Z_FINISH) == Z_OK)
1302                /* nothing */;
1303        deflateEnd(&stream);
1304        size = stream.total_out;
1305
1306        if (write(fd, compressed, size) != size)
1307                die("unable to write file");
1308        fchmod(fd, 0444);
1309        close(fd);
1310        free(compressed);
1311
1312        ret = link(tmpfile, filename);
1313        if (ret < 0) {
1314                ret = errno;
1315
1316                /*
1317                 * Coda hack - coda doesn't like cross-directory links,
1318                 * so we fall back to a rename, which will mean that it
1319                 * won't be able to check collisions, but that's not a
1320                 * big deal.
1321                 *
1322                 * When this succeeds, we just return 0. We have nothing
1323                 * left to unlink.
1324                 */
1325                if (ret == EXDEV && !rename(tmpfile, filename))
1326                        return 0;
1327        }
1328        unlink(tmpfile);
1329        if (ret) {
1330                if (ret != EEXIST) {
1331                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1332                        return -1;
1333                }
1334                /* FIXME!!! Collision check here ? */
1335        }
1336
1337        return 0;
1338}
1339
1340int write_sha1_to_fd(int fd, const unsigned char *sha1)
1341{
1342        ssize_t size;
1343        unsigned long objsize;
1344        int posn = 0;
1345        void *map = map_sha1_file_internal(sha1, &objsize);
1346        void *buf = map;
1347        void *temp_obj = NULL;
1348        z_stream stream;
1349
1350        if (!buf) {
1351                unsigned char *unpacked;
1352                unsigned long len;
1353                char type[20];
1354                char hdr[50];
1355                int hdrlen;
1356                // need to unpack and recompress it by itself
1357                unpacked = read_packed_sha1(sha1, type, &len);
1358
1359                hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1360
1361                /* Set it up */
1362                memset(&stream, 0, sizeof(stream));
1363                deflateInit(&stream, Z_BEST_COMPRESSION);
1364                size = deflateBound(&stream, len + hdrlen);
1365                temp_obj = buf = xmalloc(size);
1366
1367                /* Compress it */
1368                stream.next_out = buf;
1369                stream.avail_out = size;
1370                
1371                /* First header.. */
1372                stream.next_in = (void *)hdr;
1373                stream.avail_in = hdrlen;
1374                while (deflate(&stream, 0) == Z_OK)
1375                        /* nothing */;
1376
1377                /* Then the data itself.. */
1378                stream.next_in = unpacked;
1379                stream.avail_in = len;
1380                while (deflate(&stream, Z_FINISH) == Z_OK)
1381                        /* nothing */;
1382                deflateEnd(&stream);
1383                free(unpacked);
1384                
1385                objsize = stream.total_out;
1386        }
1387
1388        do {
1389                size = write(fd, buf + posn, objsize - posn);
1390                if (size <= 0) {
1391                        if (!size) {
1392                                fprintf(stderr, "write closed");
1393                        } else {
1394                                perror("write ");
1395                        }
1396                        return -1;
1397                }
1398                posn += size;
1399        } while (posn < objsize);
1400
1401        if (map)
1402                munmap(map, objsize);
1403        if (temp_obj)
1404                free(temp_obj);
1405
1406        return 0;
1407}
1408
1409int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1410                       size_t bufsize, size_t *bufposn)
1411{
1412        char *filename = sha1_file_name(sha1);
1413
1414        int local;
1415        z_stream stream;
1416        unsigned char real_sha1[20];
1417        unsigned char discard[4096];
1418        int ret;
1419        SHA_CTX c;
1420
1421        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1422
1423        if (local < 0)
1424                return error("Couldn't open %s\n", filename);
1425
1426        memset(&stream, 0, sizeof(stream));
1427
1428        inflateInit(&stream);
1429
1430        SHA1_Init(&c);
1431
1432        do {
1433                ssize_t size;
1434                if (*bufposn) {
1435                        stream.avail_in = *bufposn;
1436                        stream.next_in = (unsigned char *) buffer;
1437                        do {
1438                                stream.next_out = discard;
1439                                stream.avail_out = sizeof(discard);
1440                                ret = inflate(&stream, Z_SYNC_FLUSH);
1441                                SHA1_Update(&c, discard, sizeof(discard) -
1442                                            stream.avail_out);
1443                        } while (stream.avail_in && ret == Z_OK);
1444                        write(local, buffer, *bufposn - stream.avail_in);
1445                        memmove(buffer, buffer + *bufposn - stream.avail_in,
1446                                stream.avail_in);
1447                        *bufposn = stream.avail_in;
1448                        if (ret != Z_OK)
1449                                break;
1450                }
1451                size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1452                if (size <= 0) {
1453                        close(local);
1454                        unlink(filename);
1455                        if (!size)
1456                                return error("Connection closed?");
1457                        perror("Reading from connection");
1458                        return -1;
1459                }
1460                *bufposn += size;
1461        } while (1);
1462        inflateEnd(&stream);
1463
1464        close(local);
1465        SHA1_Final(real_sha1, &c);
1466        if (ret != Z_STREAM_END) {
1467                unlink(filename);
1468                return error("File %s corrupted", sha1_to_hex(sha1));
1469        }
1470        if (memcmp(sha1, real_sha1, 20)) {
1471                unlink(filename);
1472                return error("File %s has bad hash\n", sha1_to_hex(sha1));
1473        }
1474        
1475        return 0;
1476}
1477
1478int has_pack_index(const unsigned char *sha1)
1479{
1480        struct stat st;
1481        if (stat(sha1_pack_index_name(sha1), &st))
1482                return 0;
1483        return 1;
1484}
1485
1486int has_pack_file(const unsigned char *sha1)
1487{
1488        struct stat st;
1489        if (stat(sha1_pack_name(sha1), &st))
1490                return 0;
1491        return 1;
1492}
1493
1494int has_sha1_pack(const unsigned char *sha1)
1495{
1496        struct pack_entry e;
1497        return find_pack_entry(sha1, &e);
1498}
1499
1500int has_sha1_file(const unsigned char *sha1)
1501{
1502        struct stat st;
1503        struct pack_entry e;
1504
1505        if (find_pack_entry(sha1, &e))
1506                return 1;
1507        return find_sha1_file(sha1, &st) ? 1 : 0;
1508}
1509
1510int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1511{
1512        unsigned long size = st->st_size;
1513        void *buf;
1514        int ret;
1515        unsigned char hdr[50];
1516        int hdrlen;
1517
1518        buf = "";
1519        if (size)
1520                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1521        close(fd);
1522        if (buf == MAP_FAILED)
1523                return -1;
1524
1525        if (!type)
1526                type = "blob";
1527        if (write_object)
1528                ret = write_sha1_file(buf, size, type, sha1);
1529        else {
1530                write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1531                ret = 0;
1532        }
1533        if (size)
1534                munmap(buf, size);
1535        return ret;
1536}