Andrew's git / gitweb.git / sha1_file.c
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sha1_file.con commit Use Daniel's read-tree in the merge strategy 'resolve'. (2276aa6)
   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{
 245        const char *cp, *last;
 246        struct alternate_object_database *ent;
 247
 248        last = alt;
 249        while (last < ep) {
 250                cp = last;
 251                if (cp < ep && *cp == '#') {
 252                        while (cp < ep && *cp != sep)
 253                                cp++;
 254                        last = cp + 1;
 255                        continue;
 256                }
 257                for ( ; cp < ep && *cp != sep; cp++)
 258                        ;
 259                if (last != cp) {
 260                        /* 43 = 40-byte + 2 '/' + terminating NUL */
 261                        int pfxlen = cp - last;
 262                        int entlen = pfxlen + 43;
 263
 264                        ent = xmalloc(sizeof(*ent) + entlen);
 265                        *alt_odb_tail = ent;
 266                        alt_odb_tail = &(ent->next);
 267                        ent->next = NULL;
 268
 269                        memcpy(ent->base, last, pfxlen);
 270                        ent->name = ent->base + pfxlen + 1;
 271                        ent->base[pfxlen] = ent->base[pfxlen + 3] = '/';
 272                        ent->base[entlen-1] = 0;
 273                }
 274                while (cp < ep && *cp == sep)
 275                        cp++;
 276                last = cp;
 277        }
 278}
 279
 280void prepare_alt_odb(void)
 281{
 282        char path[PATH_MAX];
 283        char *map;
 284        int fd;
 285        struct stat st;
 286        char *alt;
 287
 288        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 289        if (!alt) alt = "";
 290
 291        sprintf(path, "%s/info/alternates", get_object_directory());
 292        if (alt_odb_tail)
 293                return;
 294        alt_odb_tail = &alt_odb_list;
 295        link_alt_odb_entries(alt, alt + strlen(alt), ':');
 296
 297        fd = open(path, O_RDONLY);
 298        if (fd < 0)
 299                return;
 300        if (fstat(fd, &st) || (st.st_size == 0)) {
 301                close(fd);
 302                return;
 303        }
 304        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 305        close(fd);
 306        if (map == MAP_FAILED)
 307                return;
 308
 309        link_alt_odb_entries(map, map + st.st_size, '\n');
 310        munmap(map, st.st_size);
 311}
 312
 313static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 314{
 315        char *name = sha1_file_name(sha1);
 316        struct alternate_object_database *alt;
 317
 318        if (!stat(name, st))
 319                return name;
 320        prepare_alt_odb();
 321        for (alt = alt_odb_list; alt; alt = alt->next) {
 322                name = alt->name;
 323                fill_sha1_path(name, sha1);
 324                if (!stat(alt->base, st))
 325                        return alt->base;
 326        }
 327        return NULL;
 328}
 329
 330#define PACK_MAX_SZ (1<<26)
 331static int pack_used_ctr;
 332static unsigned long pack_mapped;
 333struct packed_git *packed_git;
 334
 335static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 336                                void **idx_map_)
 337{
 338        void *idx_map;
 339        unsigned int *index;
 340        unsigned long idx_size;
 341        int nr, i;
 342        int fd = open(path, O_RDONLY);
 343        struct stat st;
 344        if (fd < 0)
 345                return -1;
 346        if (fstat(fd, &st)) {
 347                close(fd);
 348                return -1;
 349        }
 350        idx_size = st.st_size;
 351        idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 352        close(fd);
 353        if (idx_map == MAP_FAILED)
 354                return -1;
 355
 356        index = idx_map;
 357        *idx_map_ = idx_map;
 358        *idx_size_ = idx_size;
 359
 360        /* check index map */
 361        if (idx_size < 4*256 + 20 + 20)
 362                return error("index file too small");
 363        nr = 0;
 364        for (i = 0; i < 256; i++) {
 365                unsigned int n = ntohl(index[i]);
 366                if (n < nr)
 367                        return error("non-monotonic index");
 368                nr = n;
 369        }
 370
 371        /*
 372         * Total size:
 373         *  - 256 index entries 4 bytes each
 374         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 375         *  - 20-byte SHA1 of the packfile
 376         *  - 20-byte SHA1 file checksum
 377         */
 378        if (idx_size != 4*256 + nr * 24 + 20 + 20)
 379                return error("wrong index file size");
 380
 381        return 0;
 382}
 383
 384static int unuse_one_packed_git(void)
 385{
 386        struct packed_git *p, *lru = NULL;
 387
 388        for (p = packed_git; p; p = p->next) {
 389                if (p->pack_use_cnt || !p->pack_base)
 390                        continue;
 391                if (!lru || p->pack_last_used < lru->pack_last_used)
 392                        lru = p;
 393        }
 394        if (!lru)
 395                return 0;
 396        munmap(lru->pack_base, lru->pack_size);
 397        lru->pack_base = NULL;
 398        return 1;
 399}
 400
 401void unuse_packed_git(struct packed_git *p)
 402{
 403        p->pack_use_cnt--;
 404}
 405
 406int use_packed_git(struct packed_git *p)
 407{
 408        if (!p->pack_size) {
 409                struct stat st;
 410                // We created the struct before we had the pack
 411                stat(p->pack_name, &st);
 412                if (!S_ISREG(st.st_mode))
 413                        die("packfile %s not a regular file", p->pack_name);
 414                p->pack_size = st.st_size;
 415        }
 416        if (!p->pack_base) {
 417                int fd;
 418                struct stat st;
 419                void *map;
 420
 421                pack_mapped += p->pack_size;
 422                while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 423                        ; /* nothing */
 424                fd = open(p->pack_name, O_RDONLY);
 425                if (fd < 0)
 426                        die("packfile %s cannot be opened", p->pack_name);
 427                if (fstat(fd, &st)) {
 428                        close(fd);
 429                        die("packfile %s cannot be opened", p->pack_name);
 430                }
 431                if (st.st_size != p->pack_size)
 432                        die("packfile %s size mismatch.", p->pack_name);
 433                map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 434                close(fd);
 435                if (map == MAP_FAILED)
 436                        die("packfile %s cannot be mapped.", p->pack_name);
 437                p->pack_base = map;
 438
 439                /* Check if the pack file matches with the index file.
 440                 * this is cheap.
 441                 */
 442                if (memcmp((char*)(p->index_base) + p->index_size - 40,
 443                           p->pack_base + p->pack_size - 20, 20)) {
 444                              
 445                        die("packfile %s does not match index.", p->pack_name);
 446                }
 447        }
 448        p->pack_last_used = pack_used_ctr++;
 449        p->pack_use_cnt++;
 450        return 0;
 451}
 452
 453struct packed_git *add_packed_git(char *path, int path_len)
 454{
 455        struct stat st;
 456        struct packed_git *p;
 457        unsigned long idx_size;
 458        void *idx_map;
 459
 460        if (check_packed_git_idx(path, &idx_size, &idx_map))
 461                return NULL;
 462
 463        /* do we have a corresponding .pack file? */
 464        strcpy(path + path_len - 4, ".pack");
 465        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 466                munmap(idx_map, idx_size);
 467                return NULL;
 468        }
 469        /* ok, it looks sane as far as we can check without
 470         * actually mapping the pack file.
 471         */
 472        p = xmalloc(sizeof(*p) + path_len + 2);
 473        strcpy(p->pack_name, path);
 474        p->index_size = idx_size;
 475        p->pack_size = st.st_size;
 476        p->index_base = idx_map;
 477        p->next = NULL;
 478        p->pack_base = NULL;
 479        p->pack_last_used = 0;
 480        p->pack_use_cnt = 0;
 481        return p;
 482}
 483
 484struct packed_git *parse_pack_index(unsigned char *sha1)
 485{
 486        char *path = sha1_pack_index_name(sha1);
 487        return parse_pack_index_file(sha1, path);
 488}
 489
 490struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 491{
 492        struct packed_git *p;
 493        unsigned long idx_size;
 494        void *idx_map;
 495        char *path;
 496
 497        if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 498                return NULL;
 499
 500        path = sha1_pack_name(sha1);
 501
 502        p = xmalloc(sizeof(*p) + strlen(path) + 2);
 503        strcpy(p->pack_name, path);
 504        p->index_size = idx_size;
 505        p->pack_size = 0;
 506        p->index_base = idx_map;
 507        p->next = NULL;
 508        p->pack_base = NULL;
 509        p->pack_last_used = 0;
 510        p->pack_use_cnt = 0;
 511        memcpy(p->sha1, sha1, 20);
 512        return p;
 513}
 514
 515void install_packed_git(struct packed_git *pack)
 516{
 517        pack->next = packed_git;
 518        packed_git = pack;
 519}
 520
 521static void prepare_packed_git_one(char *objdir)
 522{
 523        char path[PATH_MAX];
 524        int len;
 525        DIR *dir;
 526        struct dirent *de;
 527
 528        sprintf(path, "%s/pack", objdir);
 529        len = strlen(path);
 530        dir = opendir(path);
 531        if (!dir)
 532                return;
 533        path[len++] = '/';
 534        while ((de = readdir(dir)) != NULL) {
 535                int namelen = strlen(de->d_name);
 536                struct packed_git *p;
 537
 538                if (strcmp(de->d_name + namelen - 4, ".idx"))
 539                        continue;
 540
 541                /* we have .idx.  Is it a file we can map? */
 542                strcpy(path + len, de->d_name);
 543                p = add_packed_git(path, len + namelen);
 544                if (!p)
 545                        continue;
 546                p->next = packed_git;
 547                packed_git = p;
 548        }
 549        closedir(dir);
 550}
 551
 552void prepare_packed_git(void)
 553{
 554        static int run_once = 0;
 555        struct alternate_object_database *alt;
 556
 557        if (run_once)
 558                return;
 559        prepare_packed_git_one(get_object_directory());
 560        prepare_alt_odb();
 561        for (alt = alt_odb_list; alt; alt = alt->next) {
 562                alt->name[0] = 0;
 563                prepare_packed_git_one(alt->base);
 564        }
 565        run_once = 1;
 566}
 567
 568int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 569{
 570        char header[100];
 571        unsigned char real_sha1[20];
 572        SHA_CTX c;
 573
 574        SHA1_Init(&c);
 575        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 576        SHA1_Update(&c, map, size);
 577        SHA1_Final(real_sha1, &c);
 578        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 579}
 580
 581static void *map_sha1_file_internal(const unsigned char *sha1,
 582                                    unsigned long *size)
 583{
 584        struct stat st;
 585        void *map;
 586        int fd;
 587        char *filename = find_sha1_file(sha1, &st);
 588
 589        if (!filename) {
 590                return NULL;
 591        }
 592
 593        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 594        if (fd < 0) {
 595                /* See if it works without O_NOATIME */
 596                switch (sha1_file_open_flag) {
 597                default:
 598                        fd = open(filename, O_RDONLY);
 599                        if (fd >= 0)
 600                                break;
 601                /* Fallthrough */
 602                case 0:
 603                        return NULL;
 604                }
 605
 606                /* If it failed once, it will probably fail again.
 607                 * Stop using O_NOATIME
 608                 */
 609                sha1_file_open_flag = 0;
 610        }
 611        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 612        close(fd);
 613        if (map == MAP_FAILED)
 614                return NULL;
 615        *size = st.st_size;
 616        return map;
 617}
 618
 619int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 620{
 621        /* Get the data stream */
 622        memset(stream, 0, sizeof(*stream));
 623        stream->next_in = map;
 624        stream->avail_in = mapsize;
 625        stream->next_out = buffer;
 626        stream->avail_out = size;
 627
 628        inflateInit(stream);
 629        return inflate(stream, 0);
 630}
 631
 632static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 633{
 634        int bytes = strlen(buffer) + 1;
 635        unsigned char *buf = xmalloc(1+size);
 636
 637        memcpy(buf, buffer + bytes, stream->total_out - bytes);
 638        bytes = stream->total_out - bytes;
 639        if (bytes < size) {
 640                stream->next_out = buf + bytes;
 641                stream->avail_out = size - bytes;
 642                while (inflate(stream, Z_FINISH) == Z_OK)
 643                        /* nothing */;
 644        }
 645        buf[size] = 0;
 646        inflateEnd(stream);
 647        return buf;
 648}
 649
 650/*
 651 * We used to just use "sscanf()", but that's actually way
 652 * too permissive for what we want to check. So do an anal
 653 * object header parse by hand.
 654 */
 655int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 656{
 657        int i;
 658        unsigned long size;
 659
 660        /*
 661         * The type can be at most ten bytes (including the 
 662         * terminating '\0' that we add), and is followed by
 663         * a space. 
 664         */
 665        i = 10;
 666        for (;;) {
 667                char c = *hdr++;
 668                if (c == ' ')
 669                        break;
 670                if (!--i)
 671                        return -1;
 672                *type++ = c;
 673        }
 674        *type = 0;
 675
 676        /*
 677         * The length must follow immediately, and be in canonical
 678         * decimal format (ie "010" is not valid).
 679         */
 680        size = *hdr++ - '0';
 681        if (size > 9)
 682                return -1;
 683        if (size) {
 684                for (;;) {
 685                        unsigned long c = *hdr - '0';
 686                        if (c > 9)
 687                                break;
 688                        hdr++;
 689                        size = size * 10 + c;
 690                }
 691        }
 692        *sizep = size;
 693
 694        /*
 695         * The length must be followed by a zero byte
 696         */
 697        return *hdr ? -1 : 0;
 698}
 699
 700void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 701{
 702        int ret;
 703        z_stream stream;
 704        char hdr[8192];
 705
 706        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 707        if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 708                return NULL;
 709
 710        return unpack_sha1_rest(&stream, hdr, *size);
 711}
 712
 713/* forward declaration for a mutually recursive function */
 714static int packed_object_info(struct pack_entry *entry,
 715                              char *type, unsigned long *sizep);
 716
 717static int packed_delta_info(unsigned char *base_sha1,
 718                             unsigned long delta_size,
 719                             unsigned long left,
 720                             char *type,
 721                             unsigned long *sizep,
 722                             struct packed_git *p)
 723{
 724        struct pack_entry base_ent;
 725
 726        if (left < 20)
 727                die("truncated pack file");
 728
 729        /* The base entry _must_ be in the same pack */
 730        if (!find_pack_entry_one(base_sha1, &base_ent, p))
 731                die("failed to find delta-pack base object %s",
 732                    sha1_to_hex(base_sha1));
 733
 734        /* We choose to only get the type of the base object and
 735         * ignore potentially corrupt pack file that expects the delta
 736         * based on a base with a wrong size.  This saves tons of
 737         * inflate() calls.
 738         */
 739
 740        if (packed_object_info(&base_ent, type, NULL))
 741                die("cannot get info for delta-pack base");
 742
 743        if (sizep) {
 744                const unsigned char *data;
 745                unsigned char delta_head[64];
 746                unsigned long result_size;
 747                z_stream stream;
 748                int st;
 749
 750                memset(&stream, 0, sizeof(stream));
 751
 752                data = stream.next_in = base_sha1 + 20;
 753                stream.avail_in = left - 20;
 754                stream.next_out = delta_head;
 755                stream.avail_out = sizeof(delta_head);
 756
 757                inflateInit(&stream);
 758                st = inflate(&stream, Z_FINISH);
 759                inflateEnd(&stream);
 760                if ((st != Z_STREAM_END) &&
 761                    stream.total_out != sizeof(delta_head))
 762                        die("delta data unpack-initial failed");
 763
 764                /* Examine the initial part of the delta to figure out
 765                 * the result size.
 766                 */
 767                data = delta_head;
 768                get_delta_hdr_size(&data); /* ignore base size */
 769
 770                /* Read the result size */
 771                result_size = get_delta_hdr_size(&data);
 772                *sizep = result_size;
 773        }
 774        return 0;
 775}
 776
 777static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 778        enum object_type *type, unsigned long *sizep)
 779{
 780        unsigned shift;
 781        unsigned char *pack, c;
 782        unsigned long size;
 783
 784        if (offset >= p->pack_size)
 785                die("object offset outside of pack file");
 786
 787        pack =  p->pack_base + offset;
 788        c = *pack++;
 789        offset++;
 790        *type = (c >> 4) & 7;
 791        size = c & 15;
 792        shift = 4;
 793        while (c & 0x80) {
 794                if (offset >= p->pack_size)
 795                        die("object offset outside of pack file");
 796                c = *pack++;
 797                offset++;
 798                size += (c & 0x7f) << shift;
 799                shift += 7;
 800        }
 801        *sizep = size;
 802        return offset;
 803}
 804
 805void packed_object_info_detail(struct pack_entry *e,
 806                               char *type,
 807                               unsigned long *size,
 808                               unsigned long *store_size,
 809                               int *delta_chain_length,
 810                               unsigned char *base_sha1)
 811{
 812        struct packed_git *p = e->p;
 813        unsigned long offset, left;
 814        unsigned char *pack;
 815        enum object_type kind;
 816
 817        offset = unpack_object_header(p, e->offset, &kind, size);
 818        pack = p->pack_base + offset;
 819        left = p->pack_size - offset;
 820        if (kind != OBJ_DELTA)
 821                *delta_chain_length = 0;
 822        else {
 823                int chain_length = 0;
 824                memcpy(base_sha1, pack, 20);
 825                do {
 826                        struct pack_entry base_ent;
 827                        unsigned long junk;
 828
 829                        find_pack_entry_one(pack, &base_ent, p);
 830                        offset = unpack_object_header(p, base_ent.offset,
 831                                                      &kind, &junk);
 832                        pack = p->pack_base + offset;
 833                        chain_length++;
 834                } while (kind == OBJ_DELTA);
 835                *delta_chain_length = chain_length;
 836        }
 837        switch (kind) {
 838        case OBJ_COMMIT:
 839                strcpy(type, "commit");
 840                break;
 841        case OBJ_TREE:
 842                strcpy(type, "tree");
 843                break;
 844        case OBJ_BLOB:
 845                strcpy(type, "blob");
 846                break;
 847        case OBJ_TAG:
 848                strcpy(type, "tag");
 849                break;
 850        default:
 851                die("corrupted pack file");
 852        }
 853        *store_size = 0; /* notyet */
 854}
 855
 856static int packed_object_info(struct pack_entry *entry,
 857                              char *type, unsigned long *sizep)
 858{
 859        struct packed_git *p = entry->p;
 860        unsigned long offset, size, left;
 861        unsigned char *pack;
 862        enum object_type kind;
 863        int retval;
 864
 865        if (use_packed_git(p))
 866                die("cannot map packed file");
 867
 868        offset = unpack_object_header(p, entry->offset, &kind, &size);
 869        pack = p->pack_base + offset;
 870        left = p->pack_size - offset;
 871
 872        switch (kind) {
 873        case OBJ_DELTA:
 874                retval = packed_delta_info(pack, size, left, type, sizep, p);
 875                unuse_packed_git(p);
 876                return retval;
 877        case OBJ_COMMIT:
 878                strcpy(type, "commit");
 879                break;
 880        case OBJ_TREE:
 881                strcpy(type, "tree");
 882                break;
 883        case OBJ_BLOB:
 884                strcpy(type, "blob");
 885                break;
 886        case OBJ_TAG:
 887                strcpy(type, "tag");
 888                break;
 889        default:
 890                die("corrupted pack file");
 891        }
 892        if (sizep)
 893                *sizep = size;
 894        unuse_packed_git(p);
 895        return 0;
 896}
 897
 898/* forward declaration for a mutually recursive function */
 899static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 900
 901static void *unpack_delta_entry(unsigned char *base_sha1,
 902                                unsigned long delta_size,
 903                                unsigned long left,
 904                                char *type,
 905                                unsigned long *sizep,
 906                                struct packed_git *p)
 907{
 908        struct pack_entry base_ent;
 909        void *data, *delta_data, *result, *base;
 910        unsigned long data_size, result_size, base_size;
 911        z_stream stream;
 912        int st;
 913
 914        if (left < 20)
 915                die("truncated pack file");
 916        data = base_sha1 + 20;
 917        data_size = left - 20;
 918        delta_data = xmalloc(delta_size);
 919
 920        memset(&stream, 0, sizeof(stream));
 921
 922        stream.next_in = data;
 923        stream.avail_in = data_size;
 924        stream.next_out = delta_data;
 925        stream.avail_out = delta_size;
 926
 927        inflateInit(&stream);
 928        st = inflate(&stream, Z_FINISH);
 929        inflateEnd(&stream);
 930        if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 931                die("delta data unpack failed");
 932
 933        /* The base entry _must_ be in the same pack */
 934        if (!find_pack_entry_one(base_sha1, &base_ent, p))
 935                die("failed to find delta-pack base object %s",
 936                    sha1_to_hex(base_sha1));
 937        base = unpack_entry_gently(&base_ent, type, &base_size);
 938        if (!base)
 939                die("failed to read delta-pack base object %s",
 940                    sha1_to_hex(base_sha1));
 941        result = patch_delta(base, base_size,
 942                             delta_data, delta_size,
 943                             &result_size);
 944        if (!result)
 945                die("failed to apply delta");
 946        free(delta_data);
 947        free(base);
 948        *sizep = result_size;
 949        return result;
 950}
 951
 952static void *unpack_non_delta_entry(unsigned char *data,
 953                                    unsigned long size,
 954                                    unsigned long left)
 955{
 956        int st;
 957        z_stream stream;
 958        unsigned char *buffer;
 959
 960        buffer = xmalloc(size + 1);
 961        buffer[size] = 0;
 962        memset(&stream, 0, sizeof(stream));
 963        stream.next_in = data;
 964        stream.avail_in = left;
 965        stream.next_out = buffer;
 966        stream.avail_out = size;
 967
 968        inflateInit(&stream);
 969        st = inflate(&stream, Z_FINISH);
 970        inflateEnd(&stream);
 971        if ((st != Z_STREAM_END) || stream.total_out != size) {
 972                free(buffer);
 973                return NULL;
 974        }
 975
 976        return buffer;
 977}
 978
 979static void *unpack_entry(struct pack_entry *entry,
 980                          char *type, unsigned long *sizep)
 981{
 982        struct packed_git *p = entry->p;
 983        void *retval;
 984
 985        if (use_packed_git(p))
 986                die("cannot map packed file");
 987        retval = unpack_entry_gently(entry, type, sizep);
 988        unuse_packed_git(p);
 989        if (!retval)
 990                die("corrupted pack file");
 991        return retval;
 992}
 993
 994/* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
 995void *unpack_entry_gently(struct pack_entry *entry,
 996                          char *type, unsigned long *sizep)
 997{
 998        struct packed_git *p = entry->p;
 999        unsigned long offset, size, left;
1000        unsigned char *pack;
1001        enum object_type kind;
1002        void *retval;
1003
1004        offset = unpack_object_header(p, entry->offset, &kind, &size);
1005        pack = p->pack_base + offset;
1006        left = p->pack_size - offset;
1007        switch (kind) {
1008        case OBJ_DELTA:
1009                retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1010                return retval;
1011        case OBJ_COMMIT:
1012                strcpy(type, "commit");
1013                break;
1014        case OBJ_TREE:
1015                strcpy(type, "tree");
1016                break;
1017        case OBJ_BLOB:
1018                strcpy(type, "blob");
1019                break;
1020        case OBJ_TAG:
1021                strcpy(type, "tag");
1022                break;
1023        default:
1024                return NULL;
1025        }
1026        *sizep = size;
1027        retval = unpack_non_delta_entry(pack, size, left);
1028        return retval;
1029}
1030
1031int num_packed_objects(const struct packed_git *p)
1032{
1033        /* See check_packed_git_idx() */
1034        return (p->index_size - 20 - 20 - 4*256) / 24;
1035}
1036
1037int nth_packed_object_sha1(const struct packed_git *p, int n,
1038                           unsigned char* sha1)
1039{
1040        void *index = p->index_base + 256;
1041        if (n < 0 || num_packed_objects(p) <= n)
1042                return -1;
1043        memcpy(sha1, (index + 24 * n + 4), 20);
1044        return 0;
1045}
1046
1047int find_pack_entry_one(const unsigned char *sha1,
1048                        struct pack_entry *e, struct packed_git *p)
1049{
1050        unsigned int *level1_ofs = p->index_base;
1051        int hi = ntohl(level1_ofs[*sha1]);
1052        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1053        void *index = p->index_base + 256;
1054
1055        do {
1056                int mi = (lo + hi) / 2;
1057                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1058                if (!cmp) {
1059                        e->offset = ntohl(*((int*)(index + 24 * mi)));
1060                        memcpy(e->sha1, sha1, 20);
1061                        e->p = p;
1062                        return 1;
1063                }
1064                if (cmp > 0)
1065                        hi = mi;
1066                else
1067                        lo = mi+1;
1068        } while (lo < hi);
1069        return 0;
1070}
1071
1072static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1073{
1074        struct packed_git *p;
1075        prepare_packed_git();
1076
1077        for (p = packed_git; p; p = p->next) {
1078                if (find_pack_entry_one(sha1, e, p))
1079                        return 1;
1080        }
1081        return 0;
1082}
1083
1084struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1085                                  struct packed_git *packs)
1086{
1087        struct packed_git *p;
1088        struct pack_entry e;
1089
1090        for (p = packs; p; p = p->next) {
1091                if (find_pack_entry_one(sha1, &e, p))
1092                        return p;
1093        }
1094        return NULL;
1095        
1096}
1097
1098int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1099{
1100        int status;
1101        unsigned long mapsize, size;
1102        void *map;
1103        z_stream stream;
1104        char hdr[128];
1105
1106        map = map_sha1_file_internal(sha1, &mapsize);
1107        if (!map) {
1108                struct pack_entry e;
1109
1110                if (!find_pack_entry(sha1, &e))
1111                        return error("unable to find %s", sha1_to_hex(sha1));
1112                return packed_object_info(&e, type, sizep);
1113        }
1114        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1115                status = error("unable to unpack %s header",
1116                               sha1_to_hex(sha1));
1117        if (parse_sha1_header(hdr, type, &size) < 0)
1118                status = error("unable to parse %s header", sha1_to_hex(sha1));
1119        else {
1120                status = 0;
1121                if (sizep)
1122                        *sizep = size;
1123        }
1124        inflateEnd(&stream);
1125        munmap(map, mapsize);
1126        return status;
1127}
1128
1129static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1130{
1131        struct pack_entry e;
1132
1133        if (!find_pack_entry(sha1, &e)) {
1134                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1135                return NULL;
1136        }
1137        return unpack_entry(&e, type, size);
1138}
1139
1140void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1141{
1142        unsigned long mapsize;
1143        void *map, *buf;
1144        struct pack_entry e;
1145
1146        if (find_pack_entry(sha1, &e))
1147                return read_packed_sha1(sha1, type, size);
1148        map = map_sha1_file_internal(sha1, &mapsize);
1149        if (map) {
1150                buf = unpack_sha1_file(map, mapsize, type, size);
1151                munmap(map, mapsize);
1152                return buf;
1153        }
1154        return NULL;
1155}
1156
1157void *read_object_with_reference(const unsigned char *sha1,
1158                                 const char *required_type,
1159                                 unsigned long *size,
1160                                 unsigned char *actual_sha1_return)
1161{
1162        char type[20];
1163        void *buffer;
1164        unsigned long isize;
1165        unsigned char actual_sha1[20];
1166
1167        memcpy(actual_sha1, sha1, 20);
1168        while (1) {
1169                int ref_length = -1;
1170                const char *ref_type = NULL;
1171
1172                buffer = read_sha1_file(actual_sha1, type, &isize);
1173                if (!buffer)
1174                        return NULL;
1175                if (!strcmp(type, required_type)) {
1176                        *size = isize;
1177                        if (actual_sha1_return)
1178                                memcpy(actual_sha1_return, actual_sha1, 20);
1179                        return buffer;
1180                }
1181                /* Handle references */
1182                else if (!strcmp(type, "commit"))
1183                        ref_type = "tree ";
1184                else if (!strcmp(type, "tag"))
1185                        ref_type = "object ";
1186                else {
1187                        free(buffer);
1188                        return NULL;
1189                }
1190                ref_length = strlen(ref_type);
1191
1192                if (memcmp(buffer, ref_type, ref_length) ||
1193                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
1194                        free(buffer);
1195                        return NULL;
1196                }
1197                free(buffer);
1198                /* Now we have the ID of the referred-to object in
1199                 * actual_sha1.  Check again. */
1200        }
1201}
1202
1203char *write_sha1_file_prepare(void *buf,
1204                              unsigned long len,
1205                              const char *type,
1206                              unsigned char *sha1,
1207                              unsigned char *hdr,
1208                              int *hdrlen)
1209{
1210        SHA_CTX c;
1211
1212        /* Generate the header */
1213        *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1214
1215        /* Sha1.. */
1216        SHA1_Init(&c);
1217        SHA1_Update(&c, hdr, *hdrlen);
1218        SHA1_Update(&c, buf, len);
1219        SHA1_Final(sha1, &c);
1220
1221        return sha1_file_name(sha1);
1222}
1223
1224int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1225{
1226        int size;
1227        unsigned char *compressed;
1228        z_stream stream;
1229        unsigned char sha1[20];
1230        char *filename;
1231        static char tmpfile[PATH_MAX];
1232        unsigned char hdr[50];
1233        int fd, hdrlen, ret;
1234
1235        /* Normally if we have it in the pack then we do not bother writing
1236         * it out into .git/objects/??/?{38} file.
1237         */
1238        filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1239        if (returnsha1)
1240                memcpy(returnsha1, sha1, 20);
1241        if (has_sha1_file(sha1))
1242                return 0;
1243        fd = open(filename, O_RDONLY);
1244        if (fd >= 0) {
1245                /*
1246                 * FIXME!!! We might do collision checking here, but we'd
1247                 * need to uncompress the old file and check it. Later.
1248                 */
1249                close(fd);
1250                return 0;
1251        }
1252
1253        if (errno != ENOENT) {
1254                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1255                return -1;
1256        }
1257
1258        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1259
1260        fd = mkstemp(tmpfile);
1261        if (fd < 0) {
1262                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1263                return -1;
1264        }
1265
1266        /* Set it up */
1267        memset(&stream, 0, sizeof(stream));
1268        deflateInit(&stream, Z_BEST_COMPRESSION);
1269        size = deflateBound(&stream, len+hdrlen);
1270        compressed = xmalloc(size);
1271
1272        /* Compress it */
1273        stream.next_out = compressed;
1274        stream.avail_out = size;
1275
1276        /* First header.. */
1277        stream.next_in = hdr;
1278        stream.avail_in = hdrlen;
1279        while (deflate(&stream, 0) == Z_OK)
1280                /* nothing */;
1281
1282        /* Then the data itself.. */
1283        stream.next_in = buf;
1284        stream.avail_in = len;
1285        while (deflate(&stream, Z_FINISH) == Z_OK)
1286                /* nothing */;
1287        deflateEnd(&stream);
1288        size = stream.total_out;
1289
1290        if (write(fd, compressed, size) != size)
1291                die("unable to write file");
1292        fchmod(fd, 0444);
1293        close(fd);
1294        free(compressed);
1295
1296        ret = link(tmpfile, filename);
1297        if (ret < 0) {
1298                ret = errno;
1299
1300                /*
1301                 * Coda hack - coda doesn't like cross-directory links,
1302                 * so we fall back to a rename, which will mean that it
1303                 * won't be able to check collisions, but that's not a
1304                 * big deal.
1305                 *
1306                 * When this succeeds, we just return 0. We have nothing
1307                 * left to unlink.
1308                 */
1309                if (ret == EXDEV && !rename(tmpfile, filename))
1310                        return 0;
1311        }
1312        unlink(tmpfile);
1313        if (ret) {
1314                if (ret != EEXIST) {
1315                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1316                        return -1;
1317                }
1318                /* FIXME!!! Collision check here ? */
1319        }
1320
1321        return 0;
1322}
1323
1324int write_sha1_to_fd(int fd, const unsigned char *sha1)
1325{
1326        ssize_t size;
1327        unsigned long objsize;
1328        int posn = 0;
1329        void *map = map_sha1_file_internal(sha1, &objsize);
1330        void *buf = map;
1331        void *temp_obj = NULL;
1332        z_stream stream;
1333
1334        if (!buf) {
1335                unsigned char *unpacked;
1336                unsigned long len;
1337                char type[20];
1338                char hdr[50];
1339                int hdrlen;
1340                // need to unpack and recompress it by itself
1341                unpacked = read_packed_sha1(sha1, type, &len);
1342
1343                hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1344
1345                /* Set it up */
1346                memset(&stream, 0, sizeof(stream));
1347                deflateInit(&stream, Z_BEST_COMPRESSION);
1348                size = deflateBound(&stream, len + hdrlen);
1349                temp_obj = buf = xmalloc(size);
1350
1351                /* Compress it */
1352                stream.next_out = buf;
1353                stream.avail_out = size;
1354                
1355                /* First header.. */
1356                stream.next_in = (void *)hdr;
1357                stream.avail_in = hdrlen;
1358                while (deflate(&stream, 0) == Z_OK)
1359                        /* nothing */;
1360
1361                /* Then the data itself.. */
1362                stream.next_in = unpacked;
1363                stream.avail_in = len;
1364                while (deflate(&stream, Z_FINISH) == Z_OK)
1365                        /* nothing */;
1366                deflateEnd(&stream);
1367                free(unpacked);
1368                
1369                objsize = stream.total_out;
1370        }
1371
1372        do {
1373                size = write(fd, buf + posn, objsize - posn);
1374                if (size <= 0) {
1375                        if (!size) {
1376                                fprintf(stderr, "write closed");
1377                        } else {
1378                                perror("write ");
1379                        }
1380                        return -1;
1381                }
1382                posn += size;
1383        } while (posn < objsize);
1384
1385        if (map)
1386                munmap(map, objsize);
1387        if (temp_obj)
1388                free(temp_obj);
1389
1390        return 0;
1391}
1392
1393int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1394                       size_t bufsize, size_t *bufposn)
1395{
1396        char *filename = sha1_file_name(sha1);
1397
1398        int local;
1399        z_stream stream;
1400        unsigned char real_sha1[20];
1401        unsigned char discard[4096];
1402        int ret;
1403        SHA_CTX c;
1404
1405        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1406
1407        if (local < 0)
1408                return error("Couldn't open %s\n", filename);
1409
1410        memset(&stream, 0, sizeof(stream));
1411
1412        inflateInit(&stream);
1413
1414        SHA1_Init(&c);
1415
1416        do {
1417                ssize_t size;
1418                if (*bufposn) {
1419                        stream.avail_in = *bufposn;
1420                        stream.next_in = (unsigned char *) buffer;
1421                        do {
1422                                stream.next_out = discard;
1423                                stream.avail_out = sizeof(discard);
1424                                ret = inflate(&stream, Z_SYNC_FLUSH);
1425                                SHA1_Update(&c, discard, sizeof(discard) -
1426                                            stream.avail_out);
1427                        } while (stream.avail_in && ret == Z_OK);
1428                        write(local, buffer, *bufposn - stream.avail_in);
1429                        memmove(buffer, buffer + *bufposn - stream.avail_in,
1430                                stream.avail_in);
1431                        *bufposn = stream.avail_in;
1432                        if (ret != Z_OK)
1433                                break;
1434                }
1435                size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1436                if (size <= 0) {
1437                        close(local);
1438                        unlink(filename);
1439                        if (!size)
1440                                return error("Connection closed?");
1441                        perror("Reading from connection");
1442                        return -1;
1443                }
1444                *bufposn += size;
1445        } while (1);
1446        inflateEnd(&stream);
1447
1448        close(local);
1449        SHA1_Final(real_sha1, &c);
1450        if (ret != Z_STREAM_END) {
1451                unlink(filename);
1452                return error("File %s corrupted", sha1_to_hex(sha1));
1453        }
1454        if (memcmp(sha1, real_sha1, 20)) {
1455                unlink(filename);
1456                return error("File %s has bad hash\n", sha1_to_hex(sha1));
1457        }
1458        
1459        return 0;
1460}
1461
1462int has_pack_index(const unsigned char *sha1)
1463{
1464        struct stat st;
1465        if (stat(sha1_pack_index_name(sha1), &st))
1466                return 0;
1467        return 1;
1468}
1469
1470int has_pack_file(const unsigned char *sha1)
1471{
1472        struct stat st;
1473        if (stat(sha1_pack_name(sha1), &st))
1474                return 0;
1475        return 1;
1476}
1477
1478int has_sha1_pack(const unsigned char *sha1)
1479{
1480        struct pack_entry e;
1481        return find_pack_entry(sha1, &e);
1482}
1483
1484int has_sha1_file(const unsigned char *sha1)
1485{
1486        struct stat st;
1487        struct pack_entry e;
1488
1489        if (find_pack_entry(sha1, &e))
1490                return 1;
1491        return find_sha1_file(sha1, &st) ? 1 : 0;
1492}
1493
1494int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1495{
1496        unsigned long size = st->st_size;
1497        void *buf;
1498        int ret;
1499        unsigned char hdr[50];
1500        int hdrlen;
1501
1502        buf = "";
1503        if (size)
1504                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1505        close(fd);
1506        if (buf == MAP_FAILED)
1507                return -1;
1508
1509        if (!type)
1510                type = "blob";
1511        if (write_object)
1512                ret = write_sha1_file(buf, size, type, sha1);
1513        else {
1514                write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1515                ret = 0;
1516        }
1517        if (size)
1518                munmap(buf, size);
1519        return ret;
1520}