3178fbf83a06906cb807f46e7e032c3764276474
   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 + 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 int unuse_one_packed_git(void)
 331{
 332        struct packed_git *p, *lru = NULL;
 333
 334        for (p = packed_git; p; p = p->next) {
 335                if (p->pack_use_cnt || !p->pack_base)
 336                        continue;
 337                if (!lru || p->pack_last_used < lru->pack_last_used)
 338                        lru = p;
 339        }
 340        if (!lru)
 341                return 0;
 342        munmap(lru->pack_base, lru->pack_size);
 343        lru->pack_base = NULL;
 344        return 1;
 345}
 346
 347void unuse_packed_git(struct packed_git *p)
 348{
 349        p->pack_use_cnt--;
 350}
 351
 352int use_packed_git(struct packed_git *p)
 353{
 354        if (!p->pack_base) {
 355                int fd;
 356                struct stat st;
 357                void *map;
 358
 359                pack_mapped += p->pack_size;
 360                while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 361                        ; /* nothing */
 362                fd = open(p->pack_name, O_RDONLY);
 363                if (fd < 0)
 364                        die("packfile %s cannot be opened", p->pack_name);
 365                if (fstat(fd, &st)) {
 366                        close(fd);
 367                        die("packfile %s cannot be opened", p->pack_name);
 368                }
 369                if (st.st_size != p->pack_size)
 370                        die("packfile %s size mismatch.", p->pack_name);
 371                map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 372                close(fd);
 373                if (map == MAP_FAILED)
 374                        die("packfile %s cannot be mapped.", p->pack_name);
 375                p->pack_base = map;
 376
 377                /* Check if the pack file matches with the index file.
 378                 * this is cheap.
 379                 */
 380                if (memcmp((char*)(p->index_base) + p->index_size - 40,
 381                           p->pack_base + p->pack_size - 20, 20))
 382                        die("packfile %s does not match index.", p->pack_name);
 383        }
 384        p->pack_last_used = pack_used_ctr++;
 385        p->pack_use_cnt++;
 386        return 0;
 387}
 388
 389struct packed_git *add_packed_git(char *path, int path_len)
 390{
 391        struct stat st;
 392        struct packed_git *p;
 393        unsigned long idx_size;
 394        void *idx_map;
 395
 396        if (check_packed_git_idx(path, &idx_size, &idx_map))
 397                return NULL;
 398
 399        /* do we have a corresponding .pack file? */
 400        strcpy(path + path_len - 4, ".pack");
 401        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 402                munmap(idx_map, idx_size);
 403                return NULL;
 404        }
 405        /* ok, it looks sane as far as we can check without
 406         * actually mapping the pack file.
 407         */
 408        p = xmalloc(sizeof(*p) + path_len + 2);
 409        strcpy(p->pack_name, path);
 410        p->index_size = idx_size;
 411        p->pack_size = st.st_size;
 412        p->index_base = idx_map;
 413        p->next = NULL;
 414        p->pack_base = NULL;
 415        p->pack_last_used = 0;
 416        p->pack_use_cnt = 0;
 417        return p;
 418}
 419
 420static void prepare_packed_git_one(char *objdir)
 421{
 422        char path[PATH_MAX];
 423        int len;
 424        DIR *dir;
 425        struct dirent *de;
 426
 427        sprintf(path, "%s/pack", objdir);
 428        len = strlen(path);
 429        dir = opendir(path);
 430        if (!dir)
 431                return;
 432        path[len++] = '/';
 433        while ((de = readdir(dir)) != NULL) {
 434                int namelen = strlen(de->d_name);
 435                struct packed_git *p;
 436
 437                if (strcmp(de->d_name + namelen - 4, ".idx"))
 438                        continue;
 439
 440                /* we have .idx.  Is it a file we can map? */
 441                strcpy(path + len, de->d_name);
 442                p = add_packed_git(path, len + namelen);
 443                if (!p)
 444                        continue;
 445                p->next = packed_git;
 446                packed_git = p;
 447        }
 448}
 449
 450void prepare_packed_git(void)
 451{
 452        int i;
 453        static int run_once = 0;
 454
 455        if (run_once++)
 456                return;
 457
 458        prepare_packed_git_one(get_object_directory());
 459        prepare_alt_odb();
 460        for (i = 0; alt_odb[i].base != NULL; i++) {
 461                alt_odb[i].name[0] = 0;
 462                prepare_packed_git_one(alt_odb[i].base);
 463        }
 464}
 465
 466int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 467{
 468        char header[100];
 469        unsigned char real_sha1[20];
 470        SHA_CTX c;
 471
 472        SHA1_Init(&c);
 473        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 474        SHA1_Update(&c, map, size);
 475        SHA1_Final(real_sha1, &c);
 476        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 477}
 478
 479static void *map_sha1_file_internal(const unsigned char *sha1,
 480                                    unsigned long *size,
 481                                    int say_error)
 482{
 483        struct stat st;
 484        void *map;
 485        int fd;
 486        char *filename = find_sha1_file(sha1, &st);
 487
 488        if (!filename) {
 489                if (say_error)
 490                        error("cannot map sha1 file %s", sha1_to_hex(sha1));
 491                return NULL;
 492        }
 493
 494        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 495        if (fd < 0) {
 496                /* See if it works without O_NOATIME */
 497                switch (sha1_file_open_flag) {
 498                default:
 499                        fd = open(filename, O_RDONLY);
 500                        if (fd >= 0)
 501                                break;
 502                /* Fallthrough */
 503                case 0:
 504                        if (say_error)
 505                                perror(filename);
 506                        return NULL;
 507                }
 508
 509                /* If it failed once, it will probably fail again.
 510                 * Stop using O_NOATIME
 511                 */
 512                sha1_file_open_flag = 0;
 513        }
 514        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 515        close(fd);
 516        if (-1 == (int)(long)map)
 517                return NULL;
 518        *size = st.st_size;
 519        return map;
 520}
 521
 522void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 523{
 524        return map_sha1_file_internal(sha1, size, 1);
 525}
 526
 527int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 528{
 529        /* Get the data stream */
 530        memset(stream, 0, sizeof(*stream));
 531        stream->next_in = map;
 532        stream->avail_in = mapsize;
 533        stream->next_out = buffer;
 534        stream->avail_out = size;
 535
 536        inflateInit(stream);
 537        return inflate(stream, 0);
 538}
 539
 540void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 541{
 542        int bytes = strlen(buffer) + 1;
 543        unsigned char *buf = xmalloc(1+size);
 544
 545        memcpy(buf, buffer + bytes, stream->total_out - bytes);
 546        bytes = stream->total_out - bytes;
 547        if (bytes < size) {
 548                stream->next_out = buf + bytes;
 549                stream->avail_out = size - bytes;
 550                while (inflate(stream, Z_FINISH) == Z_OK)
 551                        /* nothing */;
 552        }
 553        buf[size] = 0;
 554        inflateEnd(stream);
 555        return buf;
 556}
 557
 558/*
 559 * We used to just use "sscanf()", but that's actually way
 560 * too permissive for what we want to check. So do an anal
 561 * object header parse by hand.
 562 */
 563int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 564{
 565        int i;
 566        unsigned long size;
 567
 568        /*
 569         * The type can be at most ten bytes (including the 
 570         * terminating '\0' that we add), and is followed by
 571         * a space. 
 572         */
 573        i = 10;
 574        for (;;) {
 575                char c = *hdr++;
 576                if (c == ' ')
 577                        break;
 578                if (!--i)
 579                        return -1;
 580                *type++ = c;
 581        }
 582        *type = 0;
 583
 584        /*
 585         * The length must follow immediately, and be in canonical
 586         * decimal format (ie "010" is not valid).
 587         */
 588        size = *hdr++ - '0';
 589        if (size > 9)
 590                return -1;
 591        if (size) {
 592                for (;;) {
 593                        unsigned long c = *hdr - '0';
 594                        if (c > 9)
 595                                break;
 596                        hdr++;
 597                        size = size * 10 + c;
 598                }
 599        }
 600        *sizep = size;
 601
 602        /*
 603         * The length must be followed by a zero byte
 604         */
 605        return *hdr ? -1 : 0;
 606}
 607
 608void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 609{
 610        int ret;
 611        z_stream stream;
 612        char hdr[8192];
 613
 614        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 615        if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 616                return NULL;
 617
 618        return unpack_sha1_rest(&stream, hdr, *size);
 619}
 620
 621static int packed_delta_info(unsigned char *base_sha1,
 622                             unsigned long delta_size,
 623                             unsigned long left,
 624                             char *type,
 625                             unsigned long *sizep)
 626{
 627        if (left < 20)
 628                die("truncated pack file");
 629
 630        /* We choose to only get the type of the base object and
 631         * ignore potentially corrupt pack file that expects the delta
 632         * based on a base with a wrong size.  This saves tons of
 633         * inflate() calls.
 634         */
 635
 636        if (sha1_object_info(base_sha1, type, NULL))
 637                die("cannot get info for delta-pack base");
 638
 639        if (sizep) {
 640                const unsigned char *data;
 641                unsigned char delta_head[64];
 642                unsigned long result_size;
 643                z_stream stream;
 644                int st;
 645
 646                memset(&stream, 0, sizeof(stream));
 647
 648                data = stream.next_in = base_sha1 + 20;
 649                stream.avail_in = left - 20;
 650                stream.next_out = delta_head;
 651                stream.avail_out = sizeof(delta_head);
 652
 653                inflateInit(&stream);
 654                st = inflate(&stream, Z_FINISH);
 655                inflateEnd(&stream);
 656                if ((st != Z_STREAM_END) &&
 657                    stream.total_out != sizeof(delta_head))
 658                        die("delta data unpack-initial failed");
 659
 660                /* Examine the initial part of the delta to figure out
 661                 * the result size.
 662                 */
 663                data = delta_head;
 664                get_delta_hdr_size(&data); /* ignore base size */
 665
 666                /* Read the result size */
 667                result_size = get_delta_hdr_size(&data);
 668                *sizep = result_size;
 669        }
 670        return 0;
 671}
 672
 673static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 674        enum object_type *type, unsigned long *sizep)
 675{
 676        unsigned shift;
 677        unsigned char *pack, c;
 678        unsigned long size;
 679
 680        if (offset >= p->pack_size)
 681                die("object offset outside of pack file");
 682
 683        pack =  p->pack_base + offset;
 684        c = *pack++;
 685        offset++;
 686        *type = (c >> 4) & 7;
 687        size = c & 15;
 688        shift = 4;
 689        while (c & 0x80) {
 690                if (offset >= p->pack_size)
 691                        die("object offset outside of pack file");
 692                c = *pack++;
 693                offset++;
 694                size += (c & 0x7f) << shift;
 695                shift += 7;
 696        }
 697        *sizep = size;
 698        return offset;
 699}
 700
 701static int packed_object_info(struct pack_entry *entry,
 702                              char *type, unsigned long *sizep)
 703{
 704        struct packed_git *p = entry->p;
 705        unsigned long offset, size, left;
 706        unsigned char *pack;
 707        enum object_type kind;
 708        int retval;
 709
 710        if (use_packed_git(p))
 711                die("cannot map packed file");
 712
 713        offset = unpack_object_header(p, entry->offset, &kind, &size);
 714        pack = p->pack_base + offset;
 715        left = p->pack_size - offset;
 716
 717        switch (kind) {
 718        case OBJ_DELTA:
 719                retval = packed_delta_info(pack, size, left, type, sizep);
 720                unuse_packed_git(p);
 721                return retval;
 722        case OBJ_COMMIT:
 723                strcpy(type, "commit");
 724                break;
 725        case OBJ_TREE:
 726                strcpy(type, "tree");
 727                break;
 728        case OBJ_BLOB:
 729                strcpy(type, "blob");
 730                break;
 731        case OBJ_TAG:
 732                strcpy(type, "tag");
 733                break;
 734        default:
 735                die("corrupted pack file");
 736        }
 737        if (sizep)
 738                *sizep = size;
 739        unuse_packed_git(p);
 740        return 0;
 741}
 742
 743/* forward declaration for a mutually recursive function */
 744static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 745
 746static void *unpack_delta_entry(unsigned char *base_sha1,
 747                                unsigned long delta_size,
 748                                unsigned long left,
 749                                char *type,
 750                                unsigned long *sizep)
 751{
 752        void *data, *delta_data, *result, *base;
 753        unsigned long data_size, result_size, base_size;
 754        z_stream stream;
 755        int st;
 756
 757        if (left < 20)
 758                die("truncated pack file");
 759        data = base_sha1 + 20;
 760        data_size = left - 20;
 761        delta_data = xmalloc(delta_size);
 762
 763        memset(&stream, 0, sizeof(stream));
 764
 765        stream.next_in = data;
 766        stream.avail_in = data_size;
 767        stream.next_out = delta_data;
 768        stream.avail_out = delta_size;
 769
 770        inflateInit(&stream);
 771        st = inflate(&stream, Z_FINISH);
 772        inflateEnd(&stream);
 773        if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 774                die("delta data unpack failed");
 775
 776        /* This may recursively unpack the base, which is what we want */
 777        base = read_sha1_file(base_sha1, type, &base_size);
 778        if (!base)
 779                die("failed to read delta-pack base object %s",
 780                    sha1_to_hex(base_sha1));
 781        result = patch_delta(base, base_size,
 782                             delta_data, delta_size,
 783                             &result_size);
 784        if (!result)
 785                die("failed to apply delta");
 786        free(delta_data);
 787        free(base);
 788        *sizep = result_size;
 789        return result;
 790}
 791
 792static void *unpack_non_delta_entry(unsigned char *data,
 793                                    unsigned long size,
 794                                    unsigned long left)
 795{
 796        int st;
 797        z_stream stream;
 798        char *buffer;
 799
 800        buffer = xmalloc(size + 1);
 801        buffer[size] = 0;
 802        memset(&stream, 0, sizeof(stream));
 803        stream.next_in = data;
 804        stream.avail_in = left;
 805        stream.next_out = buffer;
 806        stream.avail_out = size;
 807
 808        inflateInit(&stream);
 809        st = inflate(&stream, Z_FINISH);
 810        inflateEnd(&stream);
 811        if ((st != Z_STREAM_END) || stream.total_out != size) {
 812                free(buffer);
 813                return NULL;
 814        }
 815
 816        return buffer;
 817}
 818
 819static void *unpack_entry(struct pack_entry *entry,
 820                          char *type, unsigned long *sizep)
 821{
 822        struct packed_git *p = entry->p;
 823        unsigned long offset, size, left;
 824        unsigned char *pack;
 825        enum object_type kind;
 826        void *retval;
 827
 828        if (use_packed_git(p))
 829                die("cannot map packed file");
 830
 831        offset = unpack_object_header(p, entry->offset, &kind, &size);
 832        pack = p->pack_base + offset;
 833        left = p->pack_size - offset;
 834        switch (kind) {
 835        case OBJ_DELTA:
 836                retval = unpack_delta_entry(pack, size, left, type, sizep);
 837                unuse_packed_git(p);
 838                return retval;
 839        case OBJ_COMMIT:
 840                strcpy(type, "commit");
 841                break;
 842        case OBJ_TREE:
 843                strcpy(type, "tree");
 844                break;
 845        case OBJ_BLOB:
 846                strcpy(type, "blob");
 847                break;
 848        case OBJ_TAG:
 849                strcpy(type, "tag");
 850                break;
 851        default:
 852                die("corrupted pack file");
 853        }
 854        *sizep = size;
 855        retval = unpack_non_delta_entry(pack, size, left);
 856        unuse_packed_git(p);
 857        return retval;
 858}
 859
 860int num_packed_objects(const struct packed_git *p)
 861{
 862        /* See check_packed_git_idx() */
 863        return (p->index_size - 20 - 20 - 4*256) / 24;
 864}
 865
 866int nth_packed_object_sha1(const struct packed_git *p, int n,
 867                           unsigned char* sha1)
 868{
 869        void *index = p->index_base + 256;
 870        if (n < 0 || num_packed_objects(p) <= n)
 871                return -1;
 872        memcpy(sha1, (index + 24 * n + 4), 20);
 873        return 0;
 874}
 875
 876static int find_pack_entry_1(const unsigned char *sha1,
 877                             struct pack_entry *e, struct packed_git *p)
 878{
 879        int *level1_ofs = p->index_base;
 880        int hi = ntohl(level1_ofs[*sha1]);
 881        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
 882        void *index = p->index_base + 256;
 883
 884        do {
 885                int mi = (lo + hi) / 2;
 886                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
 887                if (!cmp) {
 888                        e->offset = ntohl(*((int*)(index + 24 * mi)));
 889                        memcpy(e->sha1, sha1, 20);
 890                        e->p = p;
 891                        return 1;
 892                }
 893                if (cmp > 0)
 894                        hi = mi;
 895                else
 896                        lo = mi+1;
 897        } while (lo < hi);
 898        return 0;
 899}
 900
 901static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 902{
 903        struct packed_git *p;
 904        prepare_packed_git();
 905
 906        for (p = packed_git; p; p = p->next) {
 907                if (find_pack_entry_1(sha1, e, p))
 908                        return 1;
 909        }
 910        return 0;
 911}
 912
 913int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
 914{
 915        int status;
 916        unsigned long mapsize, size;
 917        void *map;
 918        z_stream stream;
 919        char hdr[128];
 920
 921        map = map_sha1_file_internal(sha1, &mapsize, 0);
 922        if (!map) {
 923                struct pack_entry e;
 924
 925                if (!find_pack_entry(sha1, &e))
 926                        return error("unable to find %s", sha1_to_hex(sha1));
 927                return packed_object_info(&e, type, sizep);
 928        }
 929        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
 930                status = error("unable to unpack %s header",
 931                               sha1_to_hex(sha1));
 932        if (parse_sha1_header(hdr, type, &size) < 0)
 933                status = error("unable to parse %s header", sha1_to_hex(sha1));
 934        else {
 935                status = 0;
 936                if (sizep)
 937                        *sizep = size;
 938        }
 939        inflateEnd(&stream);
 940        munmap(map, mapsize);
 941        return status;
 942}
 943
 944static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
 945{
 946        struct pack_entry e;
 947
 948        if (!find_pack_entry(sha1, &e)) {
 949                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
 950                return NULL;
 951        }
 952        return unpack_entry(&e, type, size);
 953}
 954
 955void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 956{
 957        unsigned long mapsize;
 958        void *map, *buf;
 959
 960        map = map_sha1_file_internal(sha1, &mapsize, 0);
 961        if (map) {
 962                buf = unpack_sha1_file(map, mapsize, type, size);
 963                munmap(map, mapsize);
 964                return buf;
 965        }
 966        return read_packed_sha1(sha1, type, size);
 967}
 968
 969void *read_object_with_reference(const unsigned char *sha1,
 970                                 const char *required_type,
 971                                 unsigned long *size,
 972                                 unsigned char *actual_sha1_return)
 973{
 974        char type[20];
 975        void *buffer;
 976        unsigned long isize;
 977        unsigned char actual_sha1[20];
 978
 979        memcpy(actual_sha1, sha1, 20);
 980        while (1) {
 981                int ref_length = -1;
 982                const char *ref_type = NULL;
 983
 984                buffer = read_sha1_file(actual_sha1, type, &isize);
 985                if (!buffer)
 986                        return NULL;
 987                if (!strcmp(type, required_type)) {
 988                        *size = isize;
 989                        if (actual_sha1_return)
 990                                memcpy(actual_sha1_return, actual_sha1, 20);
 991                        return buffer;
 992                }
 993                /* Handle references */
 994                else if (!strcmp(type, "commit"))
 995                        ref_type = "tree ";
 996                else if (!strcmp(type, "tag"))
 997                        ref_type = "object ";
 998                else {
 999                        free(buffer);
1000                        return NULL;
1001                }
1002                ref_length = strlen(ref_type);
1003
1004                if (memcmp(buffer, ref_type, ref_length) ||
1005                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
1006                        free(buffer);
1007                        return NULL;
1008                }
1009                /* Now we have the ID of the referred-to object in
1010                 * actual_sha1.  Check again. */
1011        }
1012}
1013
1014static char *write_sha1_file_prepare(void *buf,
1015                                     unsigned long len,
1016                                     const char *type,
1017                                     unsigned char *sha1,
1018                                     unsigned char *hdr,
1019                                     int *hdrlen)
1020{
1021        SHA_CTX c;
1022
1023        /* Generate the header */
1024        *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1025
1026        /* Sha1.. */
1027        SHA1_Init(&c);
1028        SHA1_Update(&c, hdr, *hdrlen);
1029        SHA1_Update(&c, buf, len);
1030        SHA1_Final(sha1, &c);
1031
1032        return sha1_file_name(sha1);
1033}
1034
1035int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1036{
1037        int size;
1038        unsigned char *compressed;
1039        z_stream stream;
1040        unsigned char sha1[20];
1041        char *filename;
1042        static char tmpfile[PATH_MAX];
1043        unsigned char hdr[50];
1044        int fd, hdrlen, ret;
1045
1046        /* Normally if we have it in the pack then we do not bother writing
1047         * it out into .git/objects/??/?{38} file.
1048         */
1049        filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1050        if (returnsha1)
1051                memcpy(returnsha1, sha1, 20);
1052        if (has_sha1_file(sha1))
1053                return 0;
1054        fd = open(filename, O_RDONLY);
1055        if (fd >= 0) {
1056                /*
1057                 * FIXME!!! We might do collision checking here, but we'd
1058                 * need to uncompress the old file and check it. Later.
1059                 */
1060                close(fd);
1061                return 0;
1062        }
1063
1064        if (errno != ENOENT) {
1065                fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1066                return -1;
1067        }
1068
1069        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1070
1071        fd = mkstemp(tmpfile);
1072        if (fd < 0) {
1073                fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1074                return -1;
1075        }
1076
1077        /* Set it up */
1078        memset(&stream, 0, sizeof(stream));
1079        deflateInit(&stream, Z_BEST_COMPRESSION);
1080        size = deflateBound(&stream, len+hdrlen);
1081        compressed = xmalloc(size);
1082
1083        /* Compress it */
1084        stream.next_out = compressed;
1085        stream.avail_out = size;
1086
1087        /* First header.. */
1088        stream.next_in = hdr;
1089        stream.avail_in = hdrlen;
1090        while (deflate(&stream, 0) == Z_OK)
1091                /* nothing */;
1092
1093        /* Then the data itself.. */
1094        stream.next_in = buf;
1095        stream.avail_in = len;
1096        while (deflate(&stream, Z_FINISH) == Z_OK)
1097                /* nothing */;
1098        deflateEnd(&stream);
1099        size = stream.total_out;
1100
1101        if (write(fd, compressed, size) != size)
1102                die("unable to write file");
1103        fchmod(fd, 0444);
1104        close(fd);
1105        free(compressed);
1106
1107        ret = link(tmpfile, filename);
1108        if (ret < 0) {
1109                ret = errno;
1110
1111                /*
1112                 * Coda hack - coda doesn't like cross-directory links,
1113                 * so we fall back to a rename, which will mean that it
1114                 * won't be able to check collisions, but that's not a
1115                 * big deal.
1116                 *
1117                 * When this succeeds, we just return 0. We have nothing
1118                 * left to unlink.
1119                 */
1120                if (ret == EXDEV && !rename(tmpfile, filename))
1121                        return 0;
1122        }
1123        unlink(tmpfile);
1124        if (ret) {
1125                if (ret != EEXIST) {
1126                        fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1127                        return -1;
1128                }
1129                /* FIXME!!! Collision check here ? */
1130        }
1131
1132        return 0;
1133}
1134
1135int write_sha1_from_fd(const unsigned char *sha1, int fd)
1136{
1137        char *filename = sha1_file_name(sha1);
1138
1139        int local;
1140        z_stream stream;
1141        unsigned char real_sha1[20];
1142        unsigned char buf[4096];
1143        unsigned char discard[4096];
1144        int ret;
1145        SHA_CTX c;
1146
1147        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1148
1149        if (local < 0)
1150                return error("Couldn't open %s\n", filename);
1151
1152        memset(&stream, 0, sizeof(stream));
1153
1154        inflateInit(&stream);
1155
1156        SHA1_Init(&c);
1157
1158        do {
1159                ssize_t size;
1160                size = read(fd, buf, 4096);
1161                if (size <= 0) {
1162                        close(local);
1163                        unlink(filename);
1164                        if (!size)
1165                                return error("Connection closed?");
1166                        perror("Reading from connection");
1167                        return -1;
1168                }
1169                write(local, buf, size);
1170                stream.avail_in = size;
1171                stream.next_in = buf;
1172                do {
1173                        stream.next_out = discard;
1174                        stream.avail_out = sizeof(discard);
1175                        ret = inflate(&stream, Z_SYNC_FLUSH);
1176                        SHA1_Update(&c, discard, sizeof(discard) -
1177                                    stream.avail_out);
1178                } while (stream.avail_in && ret == Z_OK);
1179                
1180        } while (ret == Z_OK);
1181        inflateEnd(&stream);
1182
1183        close(local);
1184        SHA1_Final(real_sha1, &c);
1185        if (ret != Z_STREAM_END) {
1186                unlink(filename);
1187                return error("File %s corrupted", sha1_to_hex(sha1));
1188        }
1189        if (memcmp(sha1, real_sha1, 20)) {
1190                unlink(filename);
1191                return error("File %s has bad hash\n", sha1_to_hex(sha1));
1192        }
1193        
1194        return 0;
1195}
1196
1197int has_sha1_file(const unsigned char *sha1)
1198{
1199        struct stat st;
1200        struct pack_entry e;
1201
1202        if (find_sha1_file(sha1, &st))
1203                return 1;
1204        return find_pack_entry(sha1, &e);
1205}
1206
1207int index_fd(unsigned char *sha1, int fd, struct stat *st)
1208{
1209        unsigned long size = st->st_size;
1210        void *buf;
1211        int ret;
1212
1213        buf = "";
1214        if (size)
1215                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1216        close(fd);
1217        if ((int)(long)buf == -1)
1218                return -1;
1219
1220        ret = write_sha1_file(buf, size, "blob", sha1);
1221        if (size)
1222                munmap(buf, size);
1223        return ret;
1224}