f6cf180bd485bc7be78e2cd969c8cd3139f6ad6d
   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 int get_sha1_file(const char *path, unsigned char *result)
  50{
  51        char buffer[60];
  52        int fd = open(path, O_RDONLY);
  53        int len;
  54
  55        if (fd < 0)
  56                return -1;
  57        len = read(fd, buffer, sizeof(buffer));
  58        close(fd);
  59        if (len < 40)
  60                return -1;
  61        return get_sha1_hex(buffer, result);
  62}
  63
  64static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
  65static void setup_git_env(void)
  66{
  67        git_dir = gitenv(GIT_DIR_ENVIRONMENT);
  68        if (!git_dir)
  69                git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
  70        git_object_dir = gitenv(DB_ENVIRONMENT);
  71        if (!git_object_dir) {
  72                git_object_dir = xmalloc(strlen(git_dir) + 9);
  73                sprintf(git_object_dir, "%s/objects", git_dir);
  74        }
  75        git_refs_dir = xmalloc(strlen(git_dir) + 6);
  76        sprintf(git_refs_dir, "%s/refs", git_dir);
  77        git_index_file = gitenv(INDEX_ENVIRONMENT);
  78        if (!git_index_file) {
  79                git_index_file = xmalloc(strlen(git_dir) + 7);
  80                sprintf(git_index_file, "%s/index", git_dir);
  81        }
  82}
  83
  84char *get_object_directory(void)
  85{
  86        if (!git_object_dir)
  87                setup_git_env();
  88        return git_object_dir;
  89}
  90
  91char *get_refs_directory(void)
  92{
  93        if (!git_refs_dir)
  94                setup_git_env();
  95        return git_refs_dir;
  96}
  97
  98char *get_index_file(void)
  99{
 100        if (!git_index_file)
 101                setup_git_env();
 102        return git_index_file;
 103}
 104
 105int get_sha1(const char *str, unsigned char *sha1)
 106{
 107        static char pathname[PATH_MAX];
 108        static const char *prefix[] = {
 109                "",
 110                "refs",
 111                "refs/tags",
 112                "refs/heads",
 113                "refs/snap",
 114                NULL
 115        };
 116        const char **p;
 117
 118        if (!get_sha1_hex(str, sha1))
 119                return 0;
 120
 121        if (!git_dir)
 122                setup_git_env();
 123        for (p = prefix; *p; p++) {
 124                snprintf(pathname, sizeof(pathname), "%s/%s/%s",
 125                         git_dir, *p, str);
 126                if (!get_sha1_file(pathname, sha1))
 127                        return 0;
 128        }
 129
 130        return -1;
 131}
 132
 133char * sha1_to_hex(const unsigned char *sha1)
 134{
 135        static char buffer[50];
 136        static const char hex[] = "0123456789abcdef";
 137        char *buf = buffer;
 138        int i;
 139
 140        for (i = 0; i < 20; i++) {
 141                unsigned int val = *sha1++;
 142                *buf++ = hex[val >> 4];
 143                *buf++ = hex[val & 0xf];
 144        }
 145        return buffer;
 146}
 147
 148static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 149{
 150        int i;
 151        for (i = 0; i < 20; i++) {
 152                static char hex[] = "0123456789abcdef";
 153                unsigned int val = sha1[i];
 154                char *pos = pathbuf + i*2 + (i > 0);
 155                *pos++ = hex[val >> 4];
 156                *pos = hex[val & 0xf];
 157        }
 158}
 159
 160/*
 161 * NOTE! This returns a statically allocated buffer, so you have to be
 162 * careful about using it. Do a "strdup()" if you need to save the
 163 * filename.
 164 *
 165 * Also note that this returns the location for creating.  Reading
 166 * SHA1 file can happen from any alternate directory listed in the
 167 * DB_ENVIRONMENT environment variable if it is not found in
 168 * the primary object database.
 169 */
 170char *sha1_file_name(const unsigned char *sha1)
 171{
 172        static char *name, *base;
 173
 174        if (!base) {
 175                const char *sha1_file_directory = get_object_directory();
 176                int len = strlen(sha1_file_directory);
 177                base = xmalloc(len + 60);
 178                memcpy(base, sha1_file_directory, len);
 179                memset(base+len, 0, 60);
 180                base[len] = '/';
 181                base[len+3] = '/';
 182                name = base + len + 1;
 183        }
 184        fill_sha1_path(name, sha1);
 185        return base;
 186}
 187
 188struct alternate_object_database *alt_odb;
 189
 190/*
 191 * Prepare alternate object database registry.
 192 * alt_odb points at an array of struct alternate_object_database.
 193 * This array is terminated with an element that has both its base
 194 * and name set to NULL.  alt_odb[n] comes from n'th non-empty
 195 * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
 196 * variable, and its base points at a statically allocated buffer
 197 * that contains "/the/directory/corresponding/to/.git/objects/...",
 198 * while its name points just after the slash at the end of
 199 * ".git/objects/" in the example above, and has enough space to hold
 200 * 40-byte hex SHA1, an extra slash for the first level indirection,
 201 * and the terminating NUL.
 202 * This function allocates the alt_odb array and all the strings
 203 * pointed by base fields of the array elements with one xmalloc();
 204 * the string pool immediately follows the array.
 205 */
 206void prepare_alt_odb(void)
 207{
 208        int pass, totlen, i;
 209        const char *cp, *last;
 210        char *op = NULL;
 211        const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
 212
 213        if (alt_odb)
 214                return;
 215        /* The first pass counts how large an area to allocate to
 216         * hold the entire alt_odb structure, including array of
 217         * structs and path buffers for them.  The second pass fills
 218         * the structure and prepares the path buffers for use by
 219         * fill_sha1_path().
 220         */
 221        for (totlen = pass = 0; pass < 2; pass++) {
 222                last = alt;
 223                i = 0;
 224                do {
 225                        cp = strchr(last, ':') ? : last + strlen(last);
 226                        if (last != cp) {
 227                                /* 43 = 40-byte + 2 '/' + terminating NUL */
 228                                int pfxlen = cp - last;
 229                                int entlen = pfxlen + 43;
 230                                if (pass == 0)
 231                                        totlen += entlen;
 232                                else {
 233                                        alt_odb[i].base = op;
 234                                        alt_odb[i].name = op + pfxlen + 1;
 235                                        memcpy(op, last, pfxlen);
 236                                        op[pfxlen] = op[pfxlen + 3] = '/';
 237                                        op[entlen-1] = 0;
 238                                        op += entlen;
 239                                }
 240                                i++;
 241                        }
 242                        while (*cp && *cp == ':')
 243                                cp++;
 244                        last = cp;
 245                } while (*cp);
 246                if (pass)
 247                        break;
 248                alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
 249                alt_odb[i].base = alt_odb[i].name = NULL;
 250                op = (char*)(&alt_odb[i+1]);
 251        }
 252}
 253
 254static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 255{
 256        int i;
 257        char *name = sha1_file_name(sha1);
 258
 259        if (!stat(name, st))
 260                return name;
 261        prepare_alt_odb();
 262        for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
 263                fill_sha1_path(name, sha1);
 264                if (!stat(alt_odb[i].base, st))
 265                        return alt_odb[i].base;
 266        }
 267        return NULL;
 268}
 269
 270#define PACK_MAX_SZ (1<<26)
 271static int pack_used_ctr;
 272static unsigned long pack_mapped;
 273struct packed_git *packed_git;
 274
 275struct pack_entry {
 276        unsigned int offset;
 277        unsigned char sha1[20];
 278        struct packed_git *p;
 279};
 280
 281static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 282                                void **idx_map_)
 283{
 284        void *idx_map;
 285        unsigned int *index;
 286        unsigned long idx_size;
 287        int nr, i;
 288        int fd = open(path, O_RDONLY);
 289        struct stat st;
 290        if (fd < 0)
 291                return -1;
 292        if (fstat(fd, &st)) {
 293                close(fd);
 294                return -1;
 295        }
 296        idx_size = st.st_size;
 297        idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 298        close(fd);
 299        if (idx_map == MAP_FAILED)
 300                return -1;
 301
 302        index = idx_map;
 303
 304        /* check index map */
 305        if (idx_size < 4*256 + 20)
 306                return error("index file too small");
 307        nr = 0;
 308        for (i = 0; i < 256; i++) {
 309                unsigned int n = ntohl(index[i]);
 310                if (n < nr)
 311                        return error("non-monotonic index");
 312                nr = n;
 313        }
 314
 315        /*
 316         * Total size:
 317         *  - 256 index entries 4 bytes each
 318         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 319         *  - 20-byte SHA1 of the packfile
 320         *  - 20-byte SHA1 file checksum
 321         */
 322        if (idx_size != 4*256 + nr * 24 + 20 + 20)
 323                return error("wrong index file size");
 324
 325        *idx_map_ = idx_map;
 326        *idx_size_ = idx_size;
 327        return 0;
 328}
 329
 330static void unuse_one_packed_git(void)
 331{
 332        /* NOTYET */
 333}
 334
 335static int use_packed_git(struct packed_git *p)
 336{
 337        if (!p->pack_base) {
 338                int fd;
 339                struct stat st;
 340                void *map;
 341
 342                pack_mapped += p->pack_size;
 343                while (PACK_MAX_SZ < pack_mapped)
 344                        unuse_one_packed_git();
 345                fd = open(p->pack_name, O_RDONLY);
 346                if (fd < 0)
 347                        return -1;
 348                if (fstat(fd, &st)) {
 349                        close(fd);
 350                        return -1;
 351                }
 352                if (st.st_size != p->pack_size)
 353                        return -1;
 354                map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 355                close(fd);
 356                if (map == MAP_FAILED)
 357                        return -1;
 358                p->pack_base = map;
 359        }
 360        p->pack_last_used = pack_used_ctr++;
 361        return 0;
 362}
 363
 364static struct packed_git *add_packed_git(char *path, int path_len)
 365{
 366        struct stat st;
 367        struct packed_git *p;
 368        unsigned long idx_size;
 369        void *idx_map;
 370
 371        if (check_packed_git_idx(path, &idx_size, &idx_map))
 372                return NULL;
 373
 374        /* do we have a corresponding .pack file? */
 375        strcpy(path + path_len - 4, ".pack");
 376        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 377                munmap(idx_map, idx_size);
 378                return NULL;
 379        }
 380        /* ok, it looks sane as far as we can check without
 381         * actually mapping the pack file.
 382         */
 383        p = xmalloc(sizeof(*p) + path_len + 2);
 384        strcpy(p->pack_name, path);
 385        p->index_size = idx_size;
 386        p->pack_size = st.st_size;
 387        p->index_base = idx_map;
 388        p->next = NULL;
 389        p->pack_base = NULL;
 390        p->pack_last_used = 0;
 391        return p;
 392}
 393
 394static void prepare_packed_git_one(char *objdir)
 395{
 396        char path[PATH_MAX];
 397        int len;
 398        DIR *dir;
 399        struct dirent *de;
 400
 401        sprintf(path, "%s/pack", objdir);
 402        len = strlen(path);
 403        dir = opendir(path);
 404        if (!dir)
 405                return;
 406        path[len++] = '/';
 407        while ((de = readdir(dir)) != NULL) {
 408                int namelen = strlen(de->d_name);
 409                struct packed_git *p;
 410
 411                if (strcmp(de->d_name + namelen - 4, ".idx"))
 412                        continue;
 413
 414                /* we have .idx.  Is it a file we can map? */
 415                strcpy(path + len, de->d_name);
 416                p = add_packed_git(path, len + namelen);
 417                if (!p)
 418                        continue;
 419                p->next = packed_git;
 420                packed_git = p;
 421        }
 422}
 423
 424void prepare_packed_git(void)
 425{
 426        int i;
 427        static int run_once = 0;
 428
 429        if (run_once++)
 430                return;
 431
 432        prepare_packed_git_one(get_object_directory());
 433        prepare_alt_odb();
 434        for (i = 0; alt_odb[i].base != NULL; i++) {
 435                alt_odb[i].name[0] = 0;
 436                prepare_packed_git_one(alt_odb[i].base);
 437        }
 438}
 439
 440int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 441{
 442        char header[100];
 443        unsigned char real_sha1[20];
 444        SHA_CTX c;
 445
 446        SHA1_Init(&c);
 447        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 448        SHA1_Update(&c, map, size);
 449        SHA1_Final(real_sha1, &c);
 450        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 451}
 452
 453static void *map_sha1_file_internal(const unsigned char *sha1,
 454                                    unsigned long *size,
 455                                    int say_error)
 456{
 457        struct stat st;
 458        void *map;
 459        int fd;
 460        char *filename = find_sha1_file(sha1, &st);
 461
 462        if (!filename) {
 463                if (say_error)
 464                        error("cannot map sha1 file %s", sha1_to_hex(sha1));
 465                return NULL;
 466        }
 467
 468        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 469        if (fd < 0) {
 470                /* See if it works without O_NOATIME */
 471                switch (sha1_file_open_flag) {
 472                default:
 473                        fd = open(filename, O_RDONLY);
 474                        if (fd >= 0)
 475                                break;
 476                /* Fallthrough */
 477                case 0:
 478                        if (say_error)
 479                                perror(filename);
 480                        return NULL;
 481                }
 482
 483                /* If it failed once, it will probably fail again.
 484                 * Stop using O_NOATIME
 485                 */
 486                sha1_file_open_flag = 0;
 487        }
 488        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 489        close(fd);
 490        if (-1 == (int)(long)map)
 491                return NULL;
 492        *size = st.st_size;
 493        return map;
 494}
 495
 496void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 497{
 498        return map_sha1_file_internal(sha1, size, 1);
 499}
 500
 501int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 502{
 503        /* Get the data stream */
 504        memset(stream, 0, sizeof(*stream));
 505        stream->next_in = map;
 506        stream->avail_in = mapsize;
 507        stream->next_out = buffer;
 508        stream->avail_out = size;
 509
 510        inflateInit(stream);
 511        return inflate(stream, 0);
 512}
 513
 514void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 515{
 516        int bytes = strlen(buffer) + 1;
 517        unsigned char *buf = xmalloc(1+size);
 518
 519        memcpy(buf, buffer + bytes, stream->total_out - bytes);
 520        bytes = stream->total_out - bytes;
 521        if (bytes < size) {
 522                stream->next_out = buf + bytes;
 523                stream->avail_out = size - bytes;
 524                while (inflate(stream, Z_FINISH) == Z_OK)
 525                        /* nothing */;
 526        }
 527        buf[size] = 0;
 528        inflateEnd(stream);
 529        return buf;
 530}
 531
 532/*
 533 * We used to just use "sscanf()", but that's actually way
 534 * too permissive for what we want to check. So do an anal
 535 * object header parse by hand.
 536 */
 537int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 538{
 539        int i;
 540        unsigned long size;
 541
 542        /*
 543         * The type can be at most ten bytes (including the 
 544         * terminating '\0' that we add), and is followed by
 545         * a space. 
 546         */
 547        i = 10;
 548        for (;;) {
 549                char c = *hdr++;
 550                if (c == ' ')
 551                        break;
 552                if (!--i)
 553                        return -1;
 554                *type++ = c;
 555        }
 556        *type = 0;
 557
 558        /*
 559         * The length must follow immediately, and be in canonical
 560         * decimal format (ie "010" is not valid).
 561         */
 562        size = *hdr++ - '0';
 563        if (size > 9)
 564                return -1;
 565        if (size) {
 566                for (;;) {
 567                        unsigned long c = *hdr - '0';
 568                        if (c > 9)
 569                                break;
 570                        hdr++;
 571                        size = size * 10 + c;
 572                }
 573        }
 574        *sizep = size;
 575
 576        /*
 577         * The length must be followed by a zero byte
 578         */
 579        return *hdr ? -1 : 0;
 580}
 581
 582void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 583{
 584        int ret;
 585        z_stream stream;
 586        char hdr[8192];
 587
 588        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 589        if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 590                return NULL;
 591
 592        return unpack_sha1_rest(&stream, hdr, *size);
 593}
 594
 595static unsigned long parse_delta_size(unsigned char **p)
 596{
 597        unsigned char c;
 598        unsigned long size = 0;
 599        unsigned shift = 0;
 600        unsigned char *data = *p;
 601
 602        do {
 603                c = *data++;
 604                size += (c & 0x7f) << shift;
 605                shift += 7;
 606        } while (c & 0x80);
 607        *p = data;
 608        return size;
 609}
 610
 611static int packed_delta_info(unsigned char *base_sha1,
 612                             unsigned long delta_size,
 613                             unsigned long left,
 614                             char *type,
 615                             unsigned long *sizep)
 616{
 617        unsigned char *data;
 618        unsigned char delta_head[64];
 619        unsigned long data_size, result_size, base_size, verify_base_size;
 620        z_stream stream;
 621        int st;
 622
 623        if (left < 20)
 624                die("truncated pack file");
 625        if (sha1_object_info(base_sha1, type, &base_size))
 626                die("cannot get info for delta-pack base");
 627
 628        data = base_sha1 + 20;
 629        data_size = left - 20;
 630
 631        memset(&stream, 0, sizeof(stream));
 632
 633        stream.next_in = data;
 634        stream.avail_in = data_size;
 635        stream.next_out = delta_head;
 636        stream.avail_out = sizeof(delta_head);
 637
 638        inflateInit(&stream);
 639        st = inflate(&stream, Z_FINISH);
 640        inflateEnd(&stream);
 641        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head))
 642                die("delta data unpack-initial failed");
 643
 644        /* Examine the initial part of the delta to figure out
 645         * the result size.  Verify the base size while we are at it.
 646         */
 647        data = delta_head;
 648        verify_base_size = parse_delta_size(&data);
 649        result_size = parse_delta_size(&data);
 650        if (verify_base_size != base_size)
 651                die("delta base size mismatch");
 652
 653        *sizep = result_size;
 654        return 0;
 655}
 656
 657static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 658        enum object_type *type, unsigned long *sizep)
 659{
 660        unsigned shift;
 661        unsigned char *pack, c;
 662        unsigned long size;
 663
 664        if (offset >= p->pack_size)
 665                die("object offset outside of pack file");
 666
 667        pack =  p->pack_base + offset;
 668        c = *pack++;
 669        offset++;
 670        *type = (c >> 4) & 7;
 671        size = c & 15;
 672        shift = 4;
 673        while (c & 0x80) {
 674                if (offset >= p->pack_size)
 675                        die("object offset outside of pack file");
 676                c = *pack++;
 677                offset++;
 678                size += (c & 0x7f) << shift;
 679                shift += 7;
 680        }
 681        *sizep = size;
 682        return offset;
 683}
 684
 685static int packed_object_info(struct pack_entry *entry,
 686                              char *type, unsigned long *sizep)
 687{
 688        struct packed_git *p = entry->p;
 689        unsigned long offset, size, left;
 690        unsigned char *pack;
 691        enum object_type kind;
 692
 693        if (use_packed_git(p))
 694                die("cannot map packed file");
 695
 696        offset = unpack_object_header(p, entry->offset, &kind, &size);
 697        pack = p->pack_base + offset;
 698        left = p->pack_size - offset;
 699
 700        switch (kind) {
 701        case OBJ_DELTA:
 702                return packed_delta_info(pack, size, left, type, sizep);
 703                break;
 704        case OBJ_COMMIT:
 705                strcpy(type, "commit");
 706                break;
 707        case OBJ_TREE:
 708                strcpy(type, "tree");
 709                break;
 710        case OBJ_BLOB:
 711                strcpy(type, "blob");
 712                break;
 713        case OBJ_TAG:
 714                strcpy(type, "tag");
 715                break;
 716        default:
 717                die("corrupted pack file");
 718        }
 719        *sizep = size;
 720        return 0;
 721}
 722
 723/* forward declaration for a mutually recursive function */
 724static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 725
 726static void *unpack_delta_entry(unsigned char *base_sha1,
 727                                unsigned long delta_size,
 728                                unsigned long left,
 729                                char *type,
 730                                unsigned long *sizep)
 731{
 732        void *data, *delta_data, *result, *base;
 733        unsigned long data_size, result_size, base_size;
 734        z_stream stream;
 735        int st;
 736
 737        if (left < 20)
 738                die("truncated pack file");
 739        data = base_sha1 + 20;
 740        data_size = left - 20;
 741        delta_data = xmalloc(delta_size);
 742
 743        memset(&stream, 0, sizeof(stream));
 744
 745        stream.next_in = data;
 746        stream.avail_in = data_size;
 747        stream.next_out = delta_data;
 748        stream.avail_out = delta_size;
 749
 750        inflateInit(&stream);
 751        st = inflate(&stream, Z_FINISH);
 752        inflateEnd(&stream);
 753        if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 754                die("delta data unpack failed");
 755
 756        /* This may recursively unpack the base, which is what we want */
 757        base = read_sha1_file(base_sha1, type, &base_size);
 758        if (!base)
 759                die("failed to read delta-pack base object %s",
 760                    sha1_to_hex(base_sha1));
 761        result = patch_delta(base, base_size,
 762                             delta_data, delta_size,
 763                             &result_size);
 764        if (!result)
 765                die("failed to apply delta");
 766        free(delta_data);
 767        free(base);
 768        *sizep = result_size;
 769        return result;
 770}
 771
 772static void *unpack_non_delta_entry(unsigned char *data,
 773                                    unsigned long size,
 774                                    unsigned long left)
 775{
 776        int st;
 777        z_stream stream;
 778        char *buffer;
 779
 780        buffer = xmalloc(size + 1);
 781        buffer[size] = 0;
 782        memset(&stream, 0, sizeof(stream));
 783        stream.next_in = data;
 784        stream.avail_in = left;
 785        stream.next_out = buffer;
 786        stream.avail_out = size;
 787
 788        inflateInit(&stream);
 789        st = inflate(&stream, Z_FINISH);
 790        inflateEnd(&stream);
 791        if ((st != Z_STREAM_END) || stream.total_out != size) {
 792                free(buffer);
 793                return NULL;
 794        }
 795
 796        return buffer;
 797}
 798
 799static void *unpack_entry(struct pack_entry *entry,
 800                          char *type, unsigned long *sizep)
 801{
 802        struct packed_git *p = entry->p;
 803        unsigned long offset, size, left;
 804        unsigned char *pack;
 805        enum object_type kind;
 806
 807        if (use_packed_git(p))
 808                die("cannot map packed file");
 809
 810        offset = unpack_object_header(p, entry->offset, &kind, &size);
 811        pack = p->pack_base + offset;
 812        left = p->pack_size - offset;
 813        switch (kind) {
 814        case OBJ_DELTA:
 815                return unpack_delta_entry(pack, size, left, type, sizep);
 816        case OBJ_COMMIT:
 817                strcpy(type, "commit");
 818                break;
 819        case OBJ_TREE:
 820                strcpy(type, "tree");
 821                break;
 822        case OBJ_BLOB:
 823                strcpy(type, "blob");
 824                break;
 825        case OBJ_TAG:
 826                strcpy(type, "tag");
 827                break;
 828        default:
 829                die("corrupted pack file");
 830        }
 831        *sizep = size;
 832        return unpack_non_delta_entry(pack, size, left);
 833}
 834
 835int num_packed_objects(const struct packed_git *p)
 836{
 837        /* See check_packed_git_idx and pack-objects.c */
 838        return (p->index_size - 20 - 20 - 4*256) / 24;
 839}
 840
 841int nth_packed_object_sha1(const struct packed_git *p, int n,
 842                           unsigned char* sha1)
 843{
 844        void *index = p->index_base + 256;
 845        if (n < 0 || num_packed_objects(p) <= n)
 846                return -1;
 847        memcpy(sha1, (index + 24 * n + 4), 20);
 848        return 0;
 849}
 850
 851static int find_pack_entry_1(const unsigned char *sha1,
 852                             struct pack_entry *e, struct packed_git *p)
 853{
 854        int *level1_ofs = p->index_base;
 855        int hi = ntohl(level1_ofs[*sha1]);
 856        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
 857        void *index = p->index_base + 256;
 858
 859        do {
 860                int mi = (lo + hi) / 2;
 861                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
 862                if (!cmp) {
 863                        e->offset = ntohl(*((int*)(index + 24 * mi)));
 864                        memcpy(e->sha1, sha1, 20);
 865                        e->p = p;
 866                        return 1;
 867                }
 868                if (cmp > 0)
 869                        hi = mi;
 870                else
 871                        lo = mi+1;
 872        } while (lo < hi);
 873        return 0;
 874}
 875
 876static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 877{
 878        struct packed_git *p;
 879        prepare_packed_git();
 880
 881        for (p = packed_git; p; p = p->next) {
 882                if (find_pack_entry_1(sha1, e, p))
 883                        return 1;
 884        }
 885        return 0;
 886}
 887
 888int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
 889{
 890        int status;
 891        unsigned long mapsize, size;
 892        void *map;
 893        z_stream stream;
 894        char hdr[128];
 895
 896        map = map_sha1_file_internal(sha1, &mapsize, 0);
 897        if (!map) {
 898                struct pack_entry e;
 899
 900                if (!find_pack_entry(sha1, &e))
 901                        return error("unable to find %s", sha1_to_hex(sha1));
 902                if (!packed_object_info(&e, type, sizep))
 903                        return 0;
 904                /* sheesh */
 905                map = unpack_entry(&e, type, sizep);
 906                free(map);
 907                return (map == NULL) ? 0 : -1;
 908        }
 909        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
 910                status = error("unable to unpack %s header",
 911                               sha1_to_hex(sha1));
 912        if (parse_sha1_header(hdr, type, &size) < 0)
 913                status = error("unable to parse %s header", sha1_to_hex(sha1));
 914        else {
 915                status = 0;
 916                *sizep = size;
 917        }
 918        inflateEnd(&stream);
 919        munmap(map, mapsize);
 920        return status;
 921}
 922
 923static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
 924{
 925        struct pack_entry e;
 926
 927        if (!find_pack_entry(sha1, &e)) {
 928                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
 929                return NULL;
 930        }
 931        return unpack_entry(&e, type, size);
 932}
 933
 934void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 935{
 936        unsigned long mapsize;
 937        void *map, *buf;
 938
 939        map = map_sha1_file_internal(sha1, &mapsize, 0);
 940        if (map) {
 941                buf = unpack_sha1_file(map, mapsize, type, size);
 942                munmap(map, mapsize);
 943                return buf;
 944        }
 945        return read_packed_sha1(sha1, type, size);
 946}
 947
 948void *read_object_with_reference(const unsigned char *sha1,
 949                                 const char *required_type,
 950                                 unsigned long *size,
 951                                 unsigned char *actual_sha1_return)
 952{
 953        char type[20];
 954        void *buffer;
 955        unsigned long isize;
 956        unsigned char actual_sha1[20];
 957
 958        memcpy(actual_sha1, sha1, 20);
 959        while (1) {
 960                int ref_length = -1;
 961                const char *ref_type = NULL;
 962
 963                buffer = read_sha1_file(actual_sha1, type, &isize);
 964                if (!buffer)
 965                        return NULL;
 966                if (!strcmp(type, required_type)) {
 967                        *size = isize;
 968                        if (actual_sha1_return)
 969                                memcpy(actual_sha1_return, actual_sha1, 20);
 970                        return buffer;
 971                }
 972                /* Handle references */
 973                else if (!strcmp(type, "commit"))
 974                        ref_type = "tree ";
 975                else if (!strcmp(type, "tag"))
 976                        ref_type = "object ";
 977                else {
 978                        free(buffer);
 979                        return NULL;
 980                }
 981                ref_length = strlen(ref_type);
 982
 983                if (memcmp(buffer, ref_type, ref_length) ||
 984                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
 985                        free(buffer);
 986                        return NULL;
 987                }
 988                /* Now we have the ID of the referred-to object in
 989                 * actual_sha1.  Check again. */
 990        }
 991}
 992
 993static char *write_sha1_file_prepare(void *buf,
 994                                     unsigned long len,
 995                                     const char *type,
 996                                     unsigned char *sha1,
 997                                     unsigned char *hdr,
 998                                     int *hdrlen)
 999{
1000        SHA_CTX c;
1001
1002        /* Generate the header */
1003        *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1004
1005        /* Sha1.. */
1006        SHA1_Init(&c);
1007        SHA1_Update(&c, hdr, *hdrlen);
1008        SHA1_Update(&c, buf, len);
1009        SHA1_Final(sha1, &c);
1010
1011        return sha1_file_name(sha1);
1012}
1013
1014int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1015{
1016        int size;
1017        unsigned char *compressed;
1018        z_stream stream;
1019        unsigned char sha1[20];
1020        char *filename;
1021        static char tmpfile[PATH_MAX];
1022        unsigned char hdr[50];
1023        int fd, hdrlen, ret;
1024
1025        /* Normally if we have it in the pack then we do not bother writing
1026         * it out into .git/objects/??/?{38} file.
1027         */
1028        filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1029        if (returnsha1)
1030                memcpy(returnsha1, sha1, 20);
1031        if (has_sha1_file(sha1))
1032                return 0;
1033        fd = open(filename, O_RDONLY);
1034        if (fd >= 0) {
1035                /*
1036                 * FIXME!!! We might do collision checking here, but we'd
1037                 * need to uncompress the old file and check it. Later.
1038                 */
1039                close(fd);
1040                return 0;
1041        }
1042
1043        if (errno != ENOENT) {
1044                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1045                return -1;
1046        }
1047
1048        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1049
1050        fd = mkstemp(tmpfile);
1051        if (fd < 0) {
1052                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1053                return -1;
1054        }
1055
1056        /* Set it up */
1057        memset(&stream, 0, sizeof(stream));
1058        deflateInit(&stream, Z_BEST_COMPRESSION);
1059        size = deflateBound(&stream, len+hdrlen);
1060        compressed = xmalloc(size);
1061
1062        /* Compress it */
1063        stream.next_out = compressed;
1064        stream.avail_out = size;
1065
1066        /* First header.. */
1067        stream.next_in = hdr;
1068        stream.avail_in = hdrlen;
1069        while (deflate(&stream, 0) == Z_OK)
1070                /* nothing */;
1071
1072        /* Then the data itself.. */
1073        stream.next_in = buf;
1074        stream.avail_in = len;
1075        while (deflate(&stream, Z_FINISH) == Z_OK)
1076                /* nothing */;
1077        deflateEnd(&stream);
1078        size = stream.total_out;
1079
1080        if (write(fd, compressed, size) != size)
1081                die("unable to write file");
1082        fchmod(fd, 0444);
1083        close(fd);
1084        free(compressed);
1085
1086        ret = link(tmpfile, filename);
1087        if (ret < 0) {
1088                ret = errno;
1089
1090                /*
1091                 * Coda hack - coda doesn't like cross-directory links,
1092                 * so we fall back to a rename, which will mean that it
1093                 * won't be able to check collisions, but that's not a
1094                 * big deal.
1095                 *
1096                 * When this succeeds, we just return 0. We have nothing
1097                 * left to unlink.
1098                 */
1099                if (ret == EXDEV && !rename(tmpfile, filename))
1100                        return 0;
1101        }
1102        unlink(tmpfile);
1103        if (ret) {
1104                if (ret != EEXIST) {
1105                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1106                        return -1;
1107                }
1108                /* FIXME!!! Collision check here ? */
1109        }
1110
1111        return 0;
1112}
1113
1114int write_sha1_from_fd(const unsigned char *sha1, int fd)
1115{
1116        char *filename = sha1_file_name(sha1);
1117
1118        int local;
1119        z_stream stream;
1120        unsigned char real_sha1[20];
1121        unsigned char buf[4096];
1122        unsigned char discard[4096];
1123        int ret;
1124        SHA_CTX c;
1125
1126        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1127
1128        if (local < 0)
1129                return error("Couldn't open %s\n", filename);
1130
1131        memset(&stream, 0, sizeof(stream));
1132
1133        inflateInit(&stream);
1134
1135        SHA1_Init(&c);
1136
1137        do {
1138                ssize_t size;
1139                size = read(fd, buf, 4096);
1140                if (size <= 0) {
1141                        close(local);
1142                        unlink(filename);
1143                        if (!size)
1144                                return error("Connection closed?");
1145                        perror("Reading from connection");
1146                        return -1;
1147                }
1148                write(local, buf, size);
1149                stream.avail_in = size;
1150                stream.next_in = buf;
1151                do {
1152                        stream.next_out = discard;
1153                        stream.avail_out = sizeof(discard);
1154                        ret = inflate(&stream, Z_SYNC_FLUSH);
1155                        SHA1_Update(&c, discard, sizeof(discard) -
1156                                    stream.avail_out);
1157                } while (stream.avail_in && ret == Z_OK);
1158                
1159        } while (ret == Z_OK);
1160        inflateEnd(&stream);
1161
1162        close(local);
1163        SHA1_Final(real_sha1, &c);
1164        if (ret != Z_STREAM_END) {
1165                unlink(filename);
1166                return error("File %s corrupted", sha1_to_hex(sha1));
1167        }
1168        if (memcmp(sha1, real_sha1, 20)) {
1169                unlink(filename);
1170                return error("File %s has bad hash\n", sha1_to_hex(sha1));
1171        }
1172        
1173        return 0;
1174}
1175
1176int has_sha1_file(const unsigned char *sha1)
1177{
1178        struct stat st;
1179        struct pack_entry e;
1180
1181        if (find_sha1_file(sha1, &st))
1182                return 1;
1183        return find_pack_entry(sha1, &e);
1184}
1185
1186int index_fd(unsigned char *sha1, int fd, struct stat *st)
1187{
1188        unsigned long size = st->st_size;
1189        void *buf;
1190        int ret;
1191
1192        buf = "";
1193        if (size)
1194                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1195        close(fd);
1196        if ((int)(long)buf == -1)
1197                return -1;
1198
1199        ret = write_sha1_file(buf, size, "blob", sha1);
1200        if (size)
1201                munmap(buf, size);
1202        return ret;
1203}