Andrew's git / gitweb.git / sha1_file.c
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sha1_file.con commit [PATCH] Fix test failure due to overly strict .git directory tests (a579def)
   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 = gitenv(GIT_DIR_ENVIRONMENT);
  54        if (!git_dir)
  55                git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
  56        git_object_dir = gitenv(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 = gitenv(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 = gitenv(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)
 244{
 245        const char *cp, *last;
 246        struct alternate_object_database *ent;
 247
 248        last = alt;
 249        do {
 250                for (cp = last; cp < ep && *cp != ':'; cp++)
 251                        ;
 252                if (last != cp) {
 253                        /* 43 = 40-byte + 2 '/' + terminating NUL */
 254                        int pfxlen = cp - last;
 255                        int entlen = pfxlen + 43;
 256
 257                        ent = xmalloc(sizeof(*ent) + entlen);
 258                        *alt_odb_tail = ent;
 259                        alt_odb_tail = &(ent->next);
 260                        ent->next = NULL;
 261
 262                        memcpy(ent->base, last, pfxlen);
 263                        ent->name = ent->base + pfxlen + 1;
 264                        ent->base[pfxlen] = ent->base[pfxlen + 3] = '/';
 265                        ent->base[entlen-1] = 0;
 266                }
 267                while (cp < ep && *cp == ':')
 268                        cp++;
 269                last = cp;
 270        } while (cp < ep);
 271}
 272
 273void prepare_alt_odb(void)
 274{
 275        char path[PATH_MAX];
 276        char *map, *ep;
 277        int fd;
 278        struct stat st;
 279        char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
 280
 281        sprintf(path, "%s/info/alternates", get_object_directory());
 282        if (alt_odb_tail)
 283                return;
 284        alt_odb_tail = &alt_odb_list;
 285        link_alt_odb_entries(alt, alt + strlen(alt));
 286
 287        fd = open(path, O_RDONLY);
 288        if (fd < 0)
 289                return;
 290        if (fstat(fd, &st) || (st.st_size == 0)) {
 291                close(fd);
 292                return;
 293        }
 294        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 295        close(fd);
 296        if (map == MAP_FAILED)
 297                return;
 298
 299        /* Remove the trailing newline */
 300        for (ep = map + st.st_size - 1; map < ep && ep[-1] == '\n'; ep--)
 301                ;
 302        link_alt_odb_entries(map, ep);
 303        munmap(map, st.st_size);
 304}
 305
 306static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 307{
 308        char *name = sha1_file_name(sha1);
 309        struct alternate_object_database *alt;
 310
 311        if (!stat(name, st))
 312                return name;
 313        prepare_alt_odb();
 314        for (alt = alt_odb_list; alt; alt = alt->next) {
 315                name = alt->name;
 316                fill_sha1_path(name, sha1);
 317                if (!stat(alt->base, st))
 318                        return alt->base;
 319        }
 320        return NULL;
 321}
 322
 323#define PACK_MAX_SZ (1<<26)
 324static int pack_used_ctr;
 325static unsigned long pack_mapped;
 326struct packed_git *packed_git;
 327
 328static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 329                                void **idx_map_)
 330{
 331        void *idx_map;
 332        unsigned int *index;
 333        unsigned long idx_size;
 334        int nr, i;
 335        int fd = open(path, O_RDONLY);
 336        struct stat st;
 337        if (fd < 0)
 338                return -1;
 339        if (fstat(fd, &st)) {
 340                close(fd);
 341                return -1;
 342        }
 343        idx_size = st.st_size;
 344        idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 345        close(fd);
 346        if (idx_map == MAP_FAILED)
 347                return -1;
 348
 349        index = idx_map;
 350        *idx_map_ = idx_map;
 351        *idx_size_ = idx_size;
 352
 353        /* check index map */
 354        if (idx_size < 4*256 + 20 + 20)
 355                return error("index file too small");
 356        nr = 0;
 357        for (i = 0; i < 256; i++) {
 358                unsigned int n = ntohl(index[i]);
 359                if (n < nr)
 360                        return error("non-monotonic index");
 361                nr = n;
 362        }
 363
 364        /*
 365         * Total size:
 366         *  - 256 index entries 4 bytes each
 367         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 368         *  - 20-byte SHA1 of the packfile
 369         *  - 20-byte SHA1 file checksum
 370         */
 371        if (idx_size != 4*256 + nr * 24 + 20 + 20)
 372                return error("wrong index file size");
 373
 374        return 0;
 375}
 376
 377static int unuse_one_packed_git(void)
 378{
 379        struct packed_git *p, *lru = NULL;
 380
 381        for (p = packed_git; p; p = p->next) {
 382                if (p->pack_use_cnt || !p->pack_base)
 383                        continue;
 384                if (!lru || p->pack_last_used < lru->pack_last_used)
 385                        lru = p;
 386        }
 387        if (!lru)
 388                return 0;
 389        munmap(lru->pack_base, lru->pack_size);
 390        lru->pack_base = NULL;
 391        return 1;
 392}
 393
 394void unuse_packed_git(struct packed_git *p)
 395{
 396        p->pack_use_cnt--;
 397}
 398
 399int use_packed_git(struct packed_git *p)
 400{
 401        if (!p->pack_size) {
 402                struct stat st;
 403                // We created the struct before we had the pack
 404                stat(p->pack_name, &st);
 405                if (!S_ISREG(st.st_mode))
 406                        die("packfile %s not a regular file", p->pack_name);
 407                p->pack_size = st.st_size;
 408        }
 409        if (!p->pack_base) {
 410                int fd;
 411                struct stat st;
 412                void *map;
 413
 414                pack_mapped += p->pack_size;
 415                while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 416                        ; /* nothing */
 417                fd = open(p->pack_name, O_RDONLY);
 418                if (fd < 0)
 419                        die("packfile %s cannot be opened", p->pack_name);
 420                if (fstat(fd, &st)) {
 421                        close(fd);
 422                        die("packfile %s cannot be opened", p->pack_name);
 423                }
 424                if (st.st_size != p->pack_size)
 425                        die("packfile %s size mismatch.", p->pack_name);
 426                map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 427                close(fd);
 428                if (map == MAP_FAILED)
 429                        die("packfile %s cannot be mapped.", p->pack_name);
 430                p->pack_base = map;
 431
 432                /* Check if the pack file matches with the index file.
 433                 * this is cheap.
 434                 */
 435                if (memcmp((char*)(p->index_base) + p->index_size - 40,
 436                           p->pack_base + p->pack_size - 20, 20)) {
 437                              
 438                        die("packfile %s does not match index.", p->pack_name);
 439                }
 440        }
 441        p->pack_last_used = pack_used_ctr++;
 442        p->pack_use_cnt++;
 443        return 0;
 444}
 445
 446struct packed_git *add_packed_git(char *path, int path_len)
 447{
 448        struct stat st;
 449        struct packed_git *p;
 450        unsigned long idx_size;
 451        void *idx_map;
 452
 453        if (check_packed_git_idx(path, &idx_size, &idx_map))
 454                return NULL;
 455
 456        /* do we have a corresponding .pack file? */
 457        strcpy(path + path_len - 4, ".pack");
 458        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 459                munmap(idx_map, idx_size);
 460                return NULL;
 461        }
 462        /* ok, it looks sane as far as we can check without
 463         * actually mapping the pack file.
 464         */
 465        p = xmalloc(sizeof(*p) + path_len + 2);
 466        strcpy(p->pack_name, path);
 467        p->index_size = idx_size;
 468        p->pack_size = st.st_size;
 469        p->index_base = idx_map;
 470        p->next = NULL;
 471        p->pack_base = NULL;
 472        p->pack_last_used = 0;
 473        p->pack_use_cnt = 0;
 474        return p;
 475}
 476
 477struct packed_git *parse_pack_index(unsigned char *sha1)
 478{
 479        char *path = sha1_pack_index_name(sha1);
 480        return parse_pack_index_file(sha1, path);
 481}
 482
 483struct packed_git *parse_pack_index_file(unsigned char *sha1, char *idx_path)
 484{
 485        struct packed_git *p;
 486        unsigned long idx_size;
 487        void *idx_map;
 488        char *path;
 489
 490        if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 491                return NULL;
 492
 493        path = sha1_pack_name(sha1);
 494
 495        p = xmalloc(sizeof(*p) + strlen(path) + 2);
 496        strcpy(p->pack_name, path);
 497        p->index_size = idx_size;
 498        p->pack_size = 0;
 499        p->index_base = idx_map;
 500        p->next = NULL;
 501        p->pack_base = NULL;
 502        p->pack_last_used = 0;
 503        p->pack_use_cnt = 0;
 504        memcpy(p->sha1, sha1, 20);
 505        return p;
 506}
 507
 508void install_packed_git(struct packed_git *pack)
 509{
 510        pack->next = packed_git;
 511        packed_git = pack;
 512}
 513
 514static void prepare_packed_git_one(char *objdir)
 515{
 516        char path[PATH_MAX];
 517        int len;
 518        DIR *dir;
 519        struct dirent *de;
 520
 521        sprintf(path, "%s/pack", objdir);
 522        len = strlen(path);
 523        dir = opendir(path);
 524        if (!dir)
 525                return;
 526        path[len++] = '/';
 527        while ((de = readdir(dir)) != NULL) {
 528                int namelen = strlen(de->d_name);
 529                struct packed_git *p;
 530
 531                if (strcmp(de->d_name + namelen - 4, ".idx"))
 532                        continue;
 533
 534                /* we have .idx.  Is it a file we can map? */
 535                strcpy(path + len, de->d_name);
 536                p = add_packed_git(path, len + namelen);
 537                if (!p)
 538                        continue;
 539                p->next = packed_git;
 540                packed_git = p;
 541        }
 542        closedir(dir);
 543}
 544
 545void prepare_packed_git(void)
 546{
 547        static int run_once = 0;
 548        struct alternate_object_database *alt;
 549
 550        if (run_once)
 551                return;
 552        prepare_packed_git_one(get_object_directory());
 553        prepare_alt_odb();
 554        for (alt = alt_odb_list; alt; alt = alt->next) {
 555                alt->name[0] = 0;
 556                prepare_packed_git_one(alt->base);
 557        }
 558        run_once = 1;
 559}
 560
 561int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 562{
 563        char header[100];
 564        unsigned char real_sha1[20];
 565        SHA_CTX c;
 566
 567        SHA1_Init(&c);
 568        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 569        SHA1_Update(&c, map, size);
 570        SHA1_Final(real_sha1, &c);
 571        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 572}
 573
 574static void *map_sha1_file_internal(const unsigned char *sha1,
 575                                    unsigned long *size)
 576{
 577        struct stat st;
 578        void *map;
 579        int fd;
 580        char *filename = find_sha1_file(sha1, &st);
 581
 582        if (!filename) {
 583                return NULL;
 584        }
 585
 586        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 587        if (fd < 0) {
 588                /* See if it works without O_NOATIME */
 589                switch (sha1_file_open_flag) {
 590                default:
 591                        fd = open(filename, O_RDONLY);
 592                        if (fd >= 0)
 593                                break;
 594                /* Fallthrough */
 595                case 0:
 596                        return NULL;
 597                }
 598
 599                /* If it failed once, it will probably fail again.
 600                 * Stop using O_NOATIME
 601                 */
 602                sha1_file_open_flag = 0;
 603        }
 604        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 605        close(fd);
 606        if (map == MAP_FAILED)
 607                return NULL;
 608        *size = st.st_size;
 609        return map;
 610}
 611
 612int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 613{
 614        /* Get the data stream */
 615        memset(stream, 0, sizeof(*stream));
 616        stream->next_in = map;
 617        stream->avail_in = mapsize;
 618        stream->next_out = buffer;
 619        stream->avail_out = size;
 620
 621        inflateInit(stream);
 622        return inflate(stream, 0);
 623}
 624
 625static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 626{
 627        int bytes = strlen(buffer) + 1;
 628        unsigned char *buf = xmalloc(1+size);
 629
 630        memcpy(buf, buffer + bytes, stream->total_out - bytes);
 631        bytes = stream->total_out - bytes;
 632        if (bytes < size) {
 633                stream->next_out = buf + bytes;
 634                stream->avail_out = size - bytes;
 635                while (inflate(stream, Z_FINISH) == Z_OK)
 636                        /* nothing */;
 637        }
 638        buf[size] = 0;
 639        inflateEnd(stream);
 640        return buf;
 641}
 642
 643/*
 644 * We used to just use "sscanf()", but that's actually way
 645 * too permissive for what we want to check. So do an anal
 646 * object header parse by hand.
 647 */
 648int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 649{
 650        int i;
 651        unsigned long size;
 652
 653        /*
 654         * The type can be at most ten bytes (including the 
 655         * terminating '\0' that we add), and is followed by
 656         * a space. 
 657         */
 658        i = 10;
 659        for (;;) {
 660                char c = *hdr++;
 661                if (c == ' ')
 662                        break;
 663                if (!--i)
 664                        return -1;
 665                *type++ = c;
 666        }
 667        *type = 0;
 668
 669        /*
 670         * The length must follow immediately, and be in canonical
 671         * decimal format (ie "010" is not valid).
 672         */
 673        size = *hdr++ - '0';
 674        if (size > 9)
 675                return -1;
 676        if (size) {
 677                for (;;) {
 678                        unsigned long c = *hdr - '0';
 679                        if (c > 9)
 680                                break;
 681                        hdr++;
 682                        size = size * 10 + c;
 683                }
 684        }
 685        *sizep = size;
 686
 687        /*
 688         * The length must be followed by a zero byte
 689         */
 690        return *hdr ? -1 : 0;
 691}
 692
 693void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 694{
 695        int ret;
 696        z_stream stream;
 697        char hdr[8192];
 698
 699        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 700        if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 701                return NULL;
 702
 703        return unpack_sha1_rest(&stream, hdr, *size);
 704}
 705
 706/* forward declaration for a mutually recursive function */
 707static int packed_object_info(struct pack_entry *entry,
 708                              char *type, unsigned long *sizep);
 709
 710static int packed_delta_info(unsigned char *base_sha1,
 711                             unsigned long delta_size,
 712                             unsigned long left,
 713                             char *type,
 714                             unsigned long *sizep,
 715                             struct packed_git *p)
 716{
 717        struct pack_entry base_ent;
 718
 719        if (left < 20)
 720                die("truncated pack file");
 721
 722        /* The base entry _must_ be in the same pack */
 723        if (!find_pack_entry_one(base_sha1, &base_ent, p))
 724                die("failed to find delta-pack base object %s",
 725                    sha1_to_hex(base_sha1));
 726
 727        /* We choose to only get the type of the base object and
 728         * ignore potentially corrupt pack file that expects the delta
 729         * based on a base with a wrong size.  This saves tons of
 730         * inflate() calls.
 731         */
 732
 733        if (packed_object_info(&base_ent, type, NULL))
 734                die("cannot get info for delta-pack base");
 735
 736        if (sizep) {
 737                const unsigned char *data;
 738                unsigned char delta_head[64];
 739                unsigned long result_size;
 740                z_stream stream;
 741                int st;
 742
 743                memset(&stream, 0, sizeof(stream));
 744
 745                data = stream.next_in = base_sha1 + 20;
 746                stream.avail_in = left - 20;
 747                stream.next_out = delta_head;
 748                stream.avail_out = sizeof(delta_head);
 749
 750                inflateInit(&stream);
 751                st = inflate(&stream, Z_FINISH);
 752                inflateEnd(&stream);
 753                if ((st != Z_STREAM_END) &&
 754                    stream.total_out != sizeof(delta_head))
 755                        die("delta data unpack-initial failed");
 756
 757                /* Examine the initial part of the delta to figure out
 758                 * the result size.
 759                 */
 760                data = delta_head;
 761                get_delta_hdr_size(&data); /* ignore base size */
 762
 763                /* Read the result size */
 764                result_size = get_delta_hdr_size(&data);
 765                *sizep = result_size;
 766        }
 767        return 0;
 768}
 769
 770static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 771        enum object_type *type, unsigned long *sizep)
 772{
 773        unsigned shift;
 774        unsigned char *pack, c;
 775        unsigned long size;
 776
 777        if (offset >= p->pack_size)
 778                die("object offset outside of pack file");
 779
 780        pack =  p->pack_base + offset;
 781        c = *pack++;
 782        offset++;
 783        *type = (c >> 4) & 7;
 784        size = c & 15;
 785        shift = 4;
 786        while (c & 0x80) {
 787                if (offset >= p->pack_size)
 788                        die("object offset outside of pack file");
 789                c = *pack++;
 790                offset++;
 791                size += (c & 0x7f) << shift;
 792                shift += 7;
 793        }
 794        *sizep = size;
 795        return offset;
 796}
 797
 798void packed_object_info_detail(struct pack_entry *e,
 799                               char *type,
 800                               unsigned long *size,
 801                               unsigned long *store_size,
 802                               int *delta_chain_length,
 803                               unsigned char *base_sha1)
 804{
 805        struct packed_git *p = e->p;
 806        unsigned long offset, left;
 807        unsigned char *pack;
 808        enum object_type kind;
 809
 810        offset = unpack_object_header(p, e->offset, &kind, size);
 811        pack = p->pack_base + offset;
 812        left = p->pack_size - offset;
 813        if (kind != OBJ_DELTA)
 814                *delta_chain_length = 0;
 815        else {
 816                int chain_length = 0;
 817                memcpy(base_sha1, pack, 20);
 818                do {
 819                        struct pack_entry base_ent;
 820                        unsigned long junk;
 821
 822                        find_pack_entry_one(pack, &base_ent, p);
 823                        offset = unpack_object_header(p, base_ent.offset,
 824                                                      &kind, &junk);
 825                        pack = p->pack_base + offset;
 826                        chain_length++;
 827                } while (kind == OBJ_DELTA);
 828                *delta_chain_length = chain_length;
 829        }
 830        switch (kind) {
 831        case OBJ_COMMIT:
 832                strcpy(type, "commit");
 833                break;
 834        case OBJ_TREE:
 835                strcpy(type, "tree");
 836                break;
 837        case OBJ_BLOB:
 838                strcpy(type, "blob");
 839                break;
 840        case OBJ_TAG:
 841                strcpy(type, "tag");
 842                break;
 843        default:
 844                die("corrupted pack file");
 845        }
 846        *store_size = 0; /* notyet */
 847}
 848
 849static int packed_object_info(struct pack_entry *entry,
 850                              char *type, unsigned long *sizep)
 851{
 852        struct packed_git *p = entry->p;
 853        unsigned long offset, size, left;
 854        unsigned char *pack;
 855        enum object_type kind;
 856        int retval;
 857
 858        if (use_packed_git(p))
 859                die("cannot map packed file");
 860
 861        offset = unpack_object_header(p, entry->offset, &kind, &size);
 862        pack = p->pack_base + offset;
 863        left = p->pack_size - offset;
 864
 865        switch (kind) {
 866        case OBJ_DELTA:
 867                retval = packed_delta_info(pack, size, left, type, sizep, p);
 868                unuse_packed_git(p);
 869                return retval;
 870        case OBJ_COMMIT:
 871                strcpy(type, "commit");
 872                break;
 873        case OBJ_TREE:
 874                strcpy(type, "tree");
 875                break;
 876        case OBJ_BLOB:
 877                strcpy(type, "blob");
 878                break;
 879        case OBJ_TAG:
 880                strcpy(type, "tag");
 881                break;
 882        default:
 883                die("corrupted pack file");
 884        }
 885        if (sizep)
 886                *sizep = size;
 887        unuse_packed_git(p);
 888        return 0;
 889}
 890
 891/* forward declaration for a mutually recursive function */
 892static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 893
 894static void *unpack_delta_entry(unsigned char *base_sha1,
 895                                unsigned long delta_size,
 896                                unsigned long left,
 897                                char *type,
 898                                unsigned long *sizep,
 899                                struct packed_git *p)
 900{
 901        struct pack_entry base_ent;
 902        void *data, *delta_data, *result, *base;
 903        unsigned long data_size, result_size, base_size;
 904        z_stream stream;
 905        int st;
 906
 907        if (left < 20)
 908                die("truncated pack file");
 909        data = base_sha1 + 20;
 910        data_size = left - 20;
 911        delta_data = xmalloc(delta_size);
 912
 913        memset(&stream, 0, sizeof(stream));
 914
 915        stream.next_in = data;
 916        stream.avail_in = data_size;
 917        stream.next_out = delta_data;
 918        stream.avail_out = delta_size;
 919
 920        inflateInit(&stream);
 921        st = inflate(&stream, Z_FINISH);
 922        inflateEnd(&stream);
 923        if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 924                die("delta data unpack failed");
 925
 926        /* The base entry _must_ be in the same pack */
 927        if (!find_pack_entry_one(base_sha1, &base_ent, p))
 928                die("failed to find delta-pack base object %s",
 929                    sha1_to_hex(base_sha1));
 930        base = unpack_entry_gently(&base_ent, type, &base_size);
 931        if (!base)
 932                die("failed to read delta-pack base object %s",
 933                    sha1_to_hex(base_sha1));
 934        result = patch_delta(base, base_size,
 935                             delta_data, delta_size,
 936                             &result_size);
 937        if (!result)
 938                die("failed to apply delta");
 939        free(delta_data);
 940        free(base);
 941        *sizep = result_size;
 942        return result;
 943}
 944
 945static void *unpack_non_delta_entry(unsigned char *data,
 946                                    unsigned long size,
 947                                    unsigned long left)
 948{
 949        int st;
 950        z_stream stream;
 951        unsigned char *buffer;
 952
 953        buffer = xmalloc(size + 1);
 954        buffer[size] = 0;
 955        memset(&stream, 0, sizeof(stream));
 956        stream.next_in = data;
 957        stream.avail_in = left;
 958        stream.next_out = buffer;
 959        stream.avail_out = size;
 960
 961        inflateInit(&stream);
 962        st = inflate(&stream, Z_FINISH);
 963        inflateEnd(&stream);
 964        if ((st != Z_STREAM_END) || stream.total_out != size) {
 965                free(buffer);
 966                return NULL;
 967        }
 968
 969        return buffer;
 970}
 971
 972static void *unpack_entry(struct pack_entry *entry,
 973                          char *type, unsigned long *sizep)
 974{
 975        struct packed_git *p = entry->p;
 976        void *retval;
 977
 978        if (use_packed_git(p))
 979                die("cannot map packed file");
 980        retval = unpack_entry_gently(entry, type, sizep);
 981        unuse_packed_git(p);
 982        if (!retval)
 983                die("corrupted pack file");
 984        return retval;
 985}
 986
 987/* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
 988void *unpack_entry_gently(struct pack_entry *entry,
 989                          char *type, unsigned long *sizep)
 990{
 991        struct packed_git *p = entry->p;
 992        unsigned long offset, size, left;
 993        unsigned char *pack;
 994        enum object_type kind;
 995        void *retval;
 996
 997        offset = unpack_object_header(p, entry->offset, &kind, &size);
 998        pack = p->pack_base + offset;
 999        left = p->pack_size - offset;
1000        switch (kind) {
1001        case OBJ_DELTA:
1002                retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1003                return retval;
1004        case OBJ_COMMIT:
1005                strcpy(type, "commit");
1006                break;
1007        case OBJ_TREE:
1008                strcpy(type, "tree");
1009                break;
1010        case OBJ_BLOB:
1011                strcpy(type, "blob");
1012                break;
1013        case OBJ_TAG:
1014                strcpy(type, "tag");
1015                break;
1016        default:
1017                return NULL;
1018        }
1019        *sizep = size;
1020        retval = unpack_non_delta_entry(pack, size, left);
1021        return retval;
1022}
1023
1024int num_packed_objects(const struct packed_git *p)
1025{
1026        /* See check_packed_git_idx() */
1027        return (p->index_size - 20 - 20 - 4*256) / 24;
1028}
1029
1030int nth_packed_object_sha1(const struct packed_git *p, int n,
1031                           unsigned char* sha1)
1032{
1033        void *index = p->index_base + 256;
1034        if (n < 0 || num_packed_objects(p) <= n)
1035                return -1;
1036        memcpy(sha1, (index + 24 * n + 4), 20);
1037        return 0;
1038}
1039
1040int find_pack_entry_one(const unsigned char *sha1,
1041                        struct pack_entry *e, struct packed_git *p)
1042{
1043        unsigned int *level1_ofs = p->index_base;
1044        int hi = ntohl(level1_ofs[*sha1]);
1045        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1046        void *index = p->index_base + 256;
1047
1048        do {
1049                int mi = (lo + hi) / 2;
1050                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1051                if (!cmp) {
1052                        e->offset = ntohl(*((int*)(index + 24 * mi)));
1053                        memcpy(e->sha1, sha1, 20);
1054                        e->p = p;
1055                        return 1;
1056                }
1057                if (cmp > 0)
1058                        hi = mi;
1059                else
1060                        lo = mi+1;
1061        } while (lo < hi);
1062        return 0;
1063}
1064
1065static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1066{
1067        struct packed_git *p;
1068        prepare_packed_git();
1069
1070        for (p = packed_git; p; p = p->next) {
1071                if (find_pack_entry_one(sha1, e, p))
1072                        return 1;
1073        }
1074        return 0;
1075}
1076
1077struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1078                                  struct packed_git *packs)
1079{
1080        struct packed_git *p;
1081        struct pack_entry e;
1082
1083        for (p = packs; p; p = p->next) {
1084                if (find_pack_entry_one(sha1, &e, p))
1085                        return p;
1086        }
1087        return NULL;
1088        
1089}
1090
1091int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1092{
1093        int status;
1094        unsigned long mapsize, size;
1095        void *map;
1096        z_stream stream;
1097        char hdr[128];
1098
1099        map = map_sha1_file_internal(sha1, &mapsize);
1100        if (!map) {
1101                struct pack_entry e;
1102
1103                if (!find_pack_entry(sha1, &e))
1104                        return error("unable to find %s", sha1_to_hex(sha1));
1105                return packed_object_info(&e, type, sizep);
1106        }
1107        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1108                status = error("unable to unpack %s header",
1109                               sha1_to_hex(sha1));
1110        if (parse_sha1_header(hdr, type, &size) < 0)
1111                status = error("unable to parse %s header", sha1_to_hex(sha1));
1112        else {
1113                status = 0;
1114                if (sizep)
1115                        *sizep = size;
1116        }
1117        inflateEnd(&stream);
1118        munmap(map, mapsize);
1119        return status;
1120}
1121
1122static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1123{
1124        struct pack_entry e;
1125
1126        if (!find_pack_entry(sha1, &e)) {
1127                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1128                return NULL;
1129        }
1130        return unpack_entry(&e, type, size);
1131}
1132
1133void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1134{
1135        unsigned long mapsize;
1136        void *map, *buf;
1137        struct pack_entry e;
1138
1139        if (find_pack_entry(sha1, &e))
1140                return read_packed_sha1(sha1, type, size);
1141        map = map_sha1_file_internal(sha1, &mapsize);
1142        if (map) {
1143                buf = unpack_sha1_file(map, mapsize, type, size);
1144                munmap(map, mapsize);
1145                return buf;
1146        }
1147        return NULL;
1148}
1149
1150void *read_object_with_reference(const unsigned char *sha1,
1151                                 const char *required_type,
1152                                 unsigned long *size,
1153                                 unsigned char *actual_sha1_return)
1154{
1155        char type[20];
1156        void *buffer;
1157        unsigned long isize;
1158        unsigned char actual_sha1[20];
1159
1160        memcpy(actual_sha1, sha1, 20);
1161        while (1) {
1162                int ref_length = -1;
1163                const char *ref_type = NULL;
1164
1165                buffer = read_sha1_file(actual_sha1, type, &isize);
1166                if (!buffer)
1167                        return NULL;
1168                if (!strcmp(type, required_type)) {
1169                        *size = isize;
1170                        if (actual_sha1_return)
1171                                memcpy(actual_sha1_return, actual_sha1, 20);
1172                        return buffer;
1173                }
1174                /* Handle references */
1175                else if (!strcmp(type, "commit"))
1176                        ref_type = "tree ";
1177                else if (!strcmp(type, "tag"))
1178                        ref_type = "object ";
1179                else {
1180                        free(buffer);
1181                        return NULL;
1182                }
1183                ref_length = strlen(ref_type);
1184
1185                if (memcmp(buffer, ref_type, ref_length) ||
1186                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
1187                        free(buffer);
1188                        return NULL;
1189                }
1190                free(buffer);
1191                /* Now we have the ID of the referred-to object in
1192                 * actual_sha1.  Check again. */
1193        }
1194}
1195
1196char *write_sha1_file_prepare(void *buf,
1197                              unsigned long len,
1198                              const char *type,
1199                              unsigned char *sha1,
1200                              unsigned char *hdr,
1201                              int *hdrlen)
1202{
1203        SHA_CTX c;
1204
1205        /* Generate the header */
1206        *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1207
1208        /* Sha1.. */
1209        SHA1_Init(&c);
1210        SHA1_Update(&c, hdr, *hdrlen);
1211        SHA1_Update(&c, buf, len);
1212        SHA1_Final(sha1, &c);
1213
1214        return sha1_file_name(sha1);
1215}
1216
1217int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1218{
1219        int size;
1220        unsigned char *compressed;
1221        z_stream stream;
1222        unsigned char sha1[20];
1223        char *filename;
1224        static char tmpfile[PATH_MAX];
1225        unsigned char hdr[50];
1226        int fd, hdrlen, ret;
1227
1228        /* Normally if we have it in the pack then we do not bother writing
1229         * it out into .git/objects/??/?{38} file.
1230         */
1231        filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1232        if (returnsha1)
1233                memcpy(returnsha1, sha1, 20);
1234        if (has_sha1_file(sha1))
1235                return 0;
1236        fd = open(filename, O_RDONLY);
1237        if (fd >= 0) {
1238                /*
1239                 * FIXME!!! We might do collision checking here, but we'd
1240                 * need to uncompress the old file and check it. Later.
1241                 */
1242                close(fd);
1243                return 0;
1244        }
1245
1246        if (errno != ENOENT) {
1247                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1248                return -1;
1249        }
1250
1251        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1252
1253        fd = mkstemp(tmpfile);
1254        if (fd < 0) {
1255                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1256                return -1;
1257        }
1258
1259        /* Set it up */
1260        memset(&stream, 0, sizeof(stream));
1261        deflateInit(&stream, Z_BEST_COMPRESSION);
1262        size = deflateBound(&stream, len+hdrlen);
1263        compressed = xmalloc(size);
1264
1265        /* Compress it */
1266        stream.next_out = compressed;
1267        stream.avail_out = size;
1268
1269        /* First header.. */
1270        stream.next_in = hdr;
1271        stream.avail_in = hdrlen;
1272        while (deflate(&stream, 0) == Z_OK)
1273                /* nothing */;
1274
1275        /* Then the data itself.. */
1276        stream.next_in = buf;
1277        stream.avail_in = len;
1278        while (deflate(&stream, Z_FINISH) == Z_OK)
1279                /* nothing */;
1280        deflateEnd(&stream);
1281        size = stream.total_out;
1282
1283        if (write(fd, compressed, size) != size)
1284                die("unable to write file");
1285        fchmod(fd, 0444);
1286        close(fd);
1287        free(compressed);
1288
1289        ret = link(tmpfile, filename);
1290        if (ret < 0) {
1291                ret = errno;
1292
1293                /*
1294                 * Coda hack - coda doesn't like cross-directory links,
1295                 * so we fall back to a rename, which will mean that it
1296                 * won't be able to check collisions, but that's not a
1297                 * big deal.
1298                 *
1299                 * When this succeeds, we just return 0. We have nothing
1300                 * left to unlink.
1301                 */
1302                if (ret == EXDEV && !rename(tmpfile, filename))
1303                        return 0;
1304        }
1305        unlink(tmpfile);
1306        if (ret) {
1307                if (ret != EEXIST) {
1308                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1309                        return -1;
1310                }
1311                /* FIXME!!! Collision check here ? */
1312        }
1313
1314        return 0;
1315}
1316
1317int write_sha1_to_fd(int fd, const unsigned char *sha1)
1318{
1319        ssize_t size;
1320        unsigned long objsize;
1321        int posn = 0;
1322        void *map = map_sha1_file_internal(sha1, &objsize);
1323        void *buf = map;
1324        void *temp_obj = NULL;
1325        z_stream stream;
1326
1327        if (!buf) {
1328                unsigned char *unpacked;
1329                unsigned long len;
1330                char type[20];
1331                char hdr[50];
1332                int hdrlen;
1333                // need to unpack and recompress it by itself
1334                unpacked = read_packed_sha1(sha1, type, &len);
1335
1336                hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1337
1338                /* Set it up */
1339                memset(&stream, 0, sizeof(stream));
1340                deflateInit(&stream, Z_BEST_COMPRESSION);
1341                size = deflateBound(&stream, len + hdrlen);
1342                temp_obj = buf = xmalloc(size);
1343
1344                /* Compress it */
1345                stream.next_out = buf;
1346                stream.avail_out = size;
1347                
1348                /* First header.. */
1349                stream.next_in = (void *)hdr;
1350                stream.avail_in = hdrlen;
1351                while (deflate(&stream, 0) == Z_OK)
1352                        /* nothing */;
1353
1354                /* Then the data itself.. */
1355                stream.next_in = unpacked;
1356                stream.avail_in = len;
1357                while (deflate(&stream, Z_FINISH) == Z_OK)
1358                        /* nothing */;
1359                deflateEnd(&stream);
1360                free(unpacked);
1361                
1362                objsize = stream.total_out;
1363        }
1364
1365        do {
1366                size = write(fd, buf + posn, objsize - posn);
1367                if (size <= 0) {
1368                        if (!size) {
1369                                fprintf(stderr, "write closed");
1370                        } else {
1371                                perror("write ");
1372                        }
1373                        return -1;
1374                }
1375                posn += size;
1376        } while (posn < objsize);
1377
1378        if (map)
1379                munmap(map, objsize);
1380        if (temp_obj)
1381                free(temp_obj);
1382
1383        return 0;
1384}
1385
1386int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1387                       size_t bufsize, size_t *bufposn)
1388{
1389        char *filename = sha1_file_name(sha1);
1390
1391        int local;
1392        z_stream stream;
1393        unsigned char real_sha1[20];
1394        unsigned char discard[4096];
1395        int ret;
1396        SHA_CTX c;
1397
1398        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1399
1400        if (local < 0)
1401                return error("Couldn't open %s\n", filename);
1402
1403        memset(&stream, 0, sizeof(stream));
1404
1405        inflateInit(&stream);
1406
1407        SHA1_Init(&c);
1408
1409        do {
1410                ssize_t size;
1411                if (*bufposn) {
1412                        stream.avail_in = *bufposn;
1413                        stream.next_in = (unsigned char *) buffer;
1414                        do {
1415                                stream.next_out = discard;
1416                                stream.avail_out = sizeof(discard);
1417                                ret = inflate(&stream, Z_SYNC_FLUSH);
1418                                SHA1_Update(&c, discard, sizeof(discard) -
1419                                            stream.avail_out);
1420                        } while (stream.avail_in && ret == Z_OK);
1421                        write(local, buffer, *bufposn - stream.avail_in);
1422                        memmove(buffer, buffer + *bufposn - stream.avail_in,
1423                                stream.avail_in);
1424                        *bufposn = stream.avail_in;
1425                        if (ret != Z_OK)
1426                                break;
1427                }
1428                size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1429                if (size <= 0) {
1430                        close(local);
1431                        unlink(filename);
1432                        if (!size)
1433                                return error("Connection closed?");
1434                        perror("Reading from connection");
1435                        return -1;
1436                }
1437                *bufposn += size;
1438        } while (1);
1439        inflateEnd(&stream);
1440
1441        close(local);
1442        SHA1_Final(real_sha1, &c);
1443        if (ret != Z_STREAM_END) {
1444                unlink(filename);
1445                return error("File %s corrupted", sha1_to_hex(sha1));
1446        }
1447        if (memcmp(sha1, real_sha1, 20)) {
1448                unlink(filename);
1449                return error("File %s has bad hash\n", sha1_to_hex(sha1));
1450        }
1451        
1452        return 0;
1453}
1454
1455int has_pack_index(const unsigned char *sha1)
1456{
1457        struct stat st;
1458        if (stat(sha1_pack_index_name(sha1), &st))
1459                return 0;
1460        return 1;
1461}
1462
1463int has_pack_file(const unsigned char *sha1)
1464{
1465        struct stat st;
1466        if (stat(sha1_pack_name(sha1), &st))
1467                return 0;
1468        return 1;
1469}
1470
1471int has_sha1_pack(const unsigned char *sha1)
1472{
1473        struct pack_entry e;
1474        return find_pack_entry(sha1, &e);
1475}
1476
1477int has_sha1_file(const unsigned char *sha1)
1478{
1479        struct stat st;
1480        struct pack_entry e;
1481
1482        if (find_pack_entry(sha1, &e))
1483                return 1;
1484        return find_sha1_file(sha1, &st) ? 1 : 0;
1485}
1486
1487int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1488{
1489        unsigned long size = st->st_size;
1490        void *buf;
1491        int ret;
1492        unsigned char hdr[50];
1493        int hdrlen;
1494
1495        buf = "";
1496        if (size)
1497                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1498        close(fd);
1499        if (buf == MAP_FAILED)
1500                return -1;
1501
1502        if (!type)
1503                type = "blob";
1504        if (write_object)
1505                ret = write_sha1_file(buf, size, type, sha1);
1506        else {
1507                write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1508                ret = 0;
1509        }
1510        if (size)
1511                munmap(buf, size);
1512        return ret;
1513}