Andrew's git - gitweb.git/blob

   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 <stdarg.h>
  10#include "cache.h"
  11
  12const char *sha1_file_directory = NULL;
  13
  14#ifndef O_NOATIME
  15#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  16#define O_NOATIME 01000000
  17#else
  18#define O_NOATIME 0
  19#endif
  20#endif
  21
  22static unsigned int sha1_file_open_flag = O_NOATIME;
  23
  24static unsigned hexval(char c)
  25{
  26        if (c >= '0' && c <= '9')
  27                return c - '0';
  28        if (c >= 'a' && c <= 'f')
  29                return c - 'a' + 10;
  30        if (c >= 'A' && c <= 'F')
  31                return c - 'A' + 10;
  32        return ~0;
  33}
  34
  35int get_sha1_hex(const char *hex, unsigned char *sha1)
  36{
  37        int i;
  38        for (i = 0; i < 20; i++) {
  39                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  40                if (val & ~0xff)
  41                        return -1;
  42                *sha1++ = val;
  43                hex += 2;
  44        }
  45        return 0;
  46}
  47
  48int get_sha1_file(const char *path, unsigned char *result)
  49{
  50        char buffer[60];
  51        int fd = open(path, O_RDONLY);
  52        int len;
  53
  54        if (fd < 0)
  55                return -1;
  56        len = read(fd, buffer, sizeof(buffer));
  57        close(fd);
  58        if (len < 40)
  59                return -1;
  60        return get_sha1_hex(buffer, result);
  61}
  62
  63static int get_parent(int index, const char *str, unsigned char *result)
  64{
  65        unsigned char sha1[20];
  66        char *buffer;
  67        unsigned long size, offset;
  68        int ret;
  69
  70        if (get_sha1(str, sha1) < 0)
  71                return -1;
  72        buffer = read_object_with_reference(sha1, "commit", &size, NULL);
  73        if (!buffer)
  74                return -1;
  75        ret = -1;
  76        offset = 46;
  77        for (;;) {
  78                if (offset + 48 > size)
  79                        break;
  80                if (memcmp(buffer + offset, "parent ", 7))
  81                        break;
  82                if (index > 0) {
  83                        offset += 48;
  84                        index--;
  85                        continue;
  86                }
  87                ret = get_sha1_hex(buffer + offset + 7, result);
  88                break;
  89        }
  90        free(buffer);
  91        return ret;     
  92}
  93
  94int get_sha1(const char *str, unsigned char *sha1)
  95{
  96        static char pathname[PATH_MAX];
  97        static const char *prefix[] = {
  98                "",
  99                "refs",
 100                "refs/tags",
 101                "refs/heads",
 102                "refs/snap",
 103                NULL
 104        };
 105        const char *gitdir;
 106        const char **p;
 107
 108        if (!get_sha1_hex(str, sha1))
 109                return 0;
 110
 111        switch (*str) {
 112        case '/':
 113                if (!get_sha1_file(str, sha1))
 114                        return 0;
 115                break;
 116        case '-':
 117                return get_parent(0, str+1, sha1);
 118        case '0' ... '9':
 119                if (str[1] == '-')
 120                        return get_parent(*str - '0', str+2, sha1);
 121                break;
 122        }
 123
 124        gitdir = ".git";
 125        for (p = prefix; *p; p++) {
 126                snprintf(pathname, sizeof(pathname), "%s/%s/%s", gitdir, *p, str);
 127                if (!get_sha1_file(pathname, sha1))
 128                        return 0;
 129        }
 130
 131        return -1;
 132}
 133
 134char * sha1_to_hex(const unsigned char *sha1)
 135{
 136        static char buffer[50];
 137        static const char hex[] = "0123456789abcdef";
 138        char *buf = buffer;
 139        int i;
 140
 141        for (i = 0; i < 20; i++) {
 142                unsigned int val = *sha1++;
 143                *buf++ = hex[val >> 4];
 144                *buf++ = hex[val & 0xf];
 145        }
 146        return buffer;
 147}
 148
 149/*
 150 * NOTE! This returns a statically allocated buffer, so you have to be
 151 * careful about using it. Do a "strdup()" if you need to save the
 152 * filename.
 153 */
 154char *sha1_file_name(const unsigned char *sha1)
 155{
 156        int i;
 157        static char *name, *base;
 158
 159        if (!base) {
 160                char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
 161                int len = strlen(sha1_file_directory);
 162                base = xmalloc(len + 60);
 163                memcpy(base, sha1_file_directory, len);
 164                memset(base+len, 0, 60);
 165                base[len] = '/';
 166                base[len+3] = '/';
 167                name = base + len + 1;
 168        }
 169        for (i = 0; i < 20; i++) {
 170                static char hex[] = "0123456789abcdef";
 171                unsigned int val = sha1[i];
 172                char *pos = name + i*2 + (i > 0);
 173                *pos++ = hex[val >> 4];
 174                *pos = hex[val & 0xf];
 175        }
 176        return base;
 177}
 178
 179int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 180{
 181        char header[100];
 182        unsigned char real_sha1[20];
 183        SHA_CTX c;
 184
 185        SHA1_Init(&c);
 186        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 187        SHA1_Update(&c, map, size);
 188        SHA1_Final(real_sha1, &c);
 189        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 190}
 191
 192void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 193{
 194        char *filename = sha1_file_name(sha1);
 195        struct stat st;
 196        void *map;
 197        int fd;
 198
 199        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 200        if (fd < 0) {
 201                /* See if it works without O_NOATIME */
 202                switch (sha1_file_open_flag) {
 203                default:
 204                        fd = open(filename, O_RDONLY);
 205                        if (fd >= 0)
 206                                break;
 207                /* Fallthrough */
 208                case 0:
 209                        perror(filename);
 210                        return NULL;
 211                }
 212
 213                /* If it failed once, it will probably fail again. Stop using O_NOATIME */
 214                sha1_file_open_flag = 0;
 215        }
 216        if (fstat(fd, &st) < 0) {
 217                close(fd);
 218                return NULL;
 219        }
 220        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 221        close(fd);
 222        if (-1 == (int)(long)map)
 223                return NULL;
 224        *size = st.st_size;
 225        return map;
 226}
 227
 228void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 229{
 230        int ret, bytes;
 231        z_stream stream;
 232        char buffer[8192];
 233        char *buf;
 234
 235        /* Get the data stream */
 236        memset(&stream, 0, sizeof(stream));
 237        stream.next_in = map;
 238        stream.avail_in = mapsize;
 239        stream.next_out = buffer;
 240        stream.avail_out = sizeof(buffer);
 241
 242        inflateInit(&stream);
 243        ret = inflate(&stream, 0);
 244        if (ret < Z_OK)
 245                return NULL;
 246        if (sscanf(buffer, "%10s %lu", type, size) != 2)
 247                return NULL;
 248
 249        bytes = strlen(buffer) + 1;
 250        buf = xmalloc(*size);
 251
 252        memcpy(buf, buffer + bytes, stream.total_out - bytes);
 253        bytes = stream.total_out - bytes;
 254        if (bytes < *size && ret == Z_OK) {
 255                stream.next_out = buf + bytes;
 256                stream.avail_out = *size - bytes;
 257                while (inflate(&stream, Z_FINISH) == Z_OK)
 258                        /* nothing */;
 259        }
 260        inflateEnd(&stream);
 261        return buf;
 262}
 263
 264void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 265{
 266        unsigned long mapsize;
 267        void *map, *buf;
 268
 269        map = map_sha1_file(sha1, &mapsize);
 270        if (map) {
 271                buf = unpack_sha1_file(map, mapsize, type, size);
 272                munmap(map, mapsize);
 273                return buf;
 274        }
 275        return NULL;
 276}
 277
 278void *read_object_with_reference(const unsigned char *sha1,
 279                                 const unsigned char *required_type,
 280                                 unsigned long *size,
 281                                 unsigned char *actual_sha1_return)
 282{
 283        char type[20];
 284        void *buffer;
 285        unsigned long isize;
 286        unsigned char actual_sha1[20];
 287
 288        memcpy(actual_sha1, sha1, 20);
 289        while (1) {
 290                int ref_length = -1;
 291                const char *ref_type = NULL;
 292
 293                buffer = read_sha1_file(actual_sha1, type, &isize);
 294                if (!buffer)
 295                        return NULL;
 296                if (!strcmp(type, required_type)) {
 297                        *size = isize;
 298                        if (actual_sha1_return)
 299                                memcpy(actual_sha1_return, actual_sha1, 20);
 300                        return buffer;
 301                }
 302                /* Handle references */
 303                else if (!strcmp(type, "commit"))
 304                        ref_type = "tree ";
 305                else if (!strcmp(type, "tag"))
 306                        ref_type = "object ";
 307                else {
 308                        free(buffer);
 309                        return NULL;
 310                }
 311                ref_length = strlen(ref_type);
 312
 313                if (memcmp(buffer, ref_type, ref_length) ||
 314                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
 315                        free(buffer);
 316                        return NULL;
 317                }
 318                /* Now we have the ID of the referred-to object in
 319                 * actual_sha1.  Check again. */
 320        }
 321}
 322
 323int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 324{
 325        int size;
 326        char *compressed;
 327        z_stream stream;
 328        unsigned char sha1[20];
 329        SHA_CTX c;
 330        char *filename;
 331        char hdr[50];
 332        int fd, hdrlen;
 333
 334        /* Generate the header */
 335        hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
 336
 337        /* Sha1.. */
 338        SHA1_Init(&c);
 339        SHA1_Update(&c, hdr, hdrlen);
 340        SHA1_Update(&c, buf, len);
 341        SHA1_Final(sha1, &c);
 342
 343        if (returnsha1)
 344                memcpy(returnsha1, sha1, 20);
 345
 346        filename = sha1_file_name(sha1);
 347        fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 348        if (fd < 0) {
 349                if (errno != EEXIST)
 350                        return -1;
 351
 352                /*
 353                 * We might do collision checking here, but we'd need to
 354                 * uncompress the old file and check it. Later.
 355                 */
 356                return 0;
 357        }
 358
 359        /* Set it up */
 360        memset(&stream, 0, sizeof(stream));
 361        deflateInit(&stream, Z_BEST_COMPRESSION);
 362        size = deflateBound(&stream, len+hdrlen);
 363        compressed = xmalloc(size);
 364
 365        /* Compress it */
 366        stream.next_out = compressed;
 367        stream.avail_out = size;
 368
 369        /* First header.. */
 370        stream.next_in = hdr;
 371        stream.avail_in = hdrlen;
 372        while (deflate(&stream, 0) == Z_OK)
 373                /* nothing */
 374
 375        /* Then the data itself.. */
 376        stream.next_in = buf;
 377        stream.avail_in = len;
 378        while (deflate(&stream, Z_FINISH) == Z_OK)
 379                /* nothing */;
 380        deflateEnd(&stream);
 381        size = stream.total_out;
 382
 383        if (write(fd, compressed, size) != size)
 384                die("unable to write file");
 385        close(fd);
 386                
 387        return 0;
 388}
 389
 390static inline int collision_check(char *filename, void *buf, unsigned int size)
 391{
 392#ifdef COLLISION_CHECK
 393        void *map;
 394        int fd = open(filename, O_RDONLY);
 395        struct stat st;
 396        int cmp;
 397
 398        /* Unreadable object, or object went away? Strange. */
 399        if (fd < 0)
 400                return -1;
 401
 402        if (fstat(fd, &st) < 0 || size != st.st_size)
 403                return -1;
 404
 405        map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 406        close(fd);
 407        if (map == MAP_FAILED)
 408                return -1;
 409        cmp = memcmp(buf, map, size);
 410        munmap(map, size);
 411        if (cmp)
 412                return -1;
 413#endif
 414        return 0;
 415}
 416
 417int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 418{
 419        char *filename = sha1_file_name(sha1);
 420        int fd;
 421
 422        fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 423        if (fd < 0) {
 424                if (errno != EEXIST)
 425                        return -1;
 426                if (collision_check(filename, buf, size))
 427                        return error("SHA1 collision detected!"
 428                                        " This is bad, bad, BAD!\a\n");
 429                return 0;
 430        }
 431        write(fd, buf, size);
 432        close(fd);
 433        return 0;
 434}
 435
 436int write_sha1_from_fd(const unsigned char *sha1, int fd)
 437{
 438        char *filename = sha1_file_name(sha1);
 439
 440        int local;
 441        z_stream stream;
 442        unsigned char real_sha1[20];
 443        char buf[4096];
 444        char discard[4096];
 445        int ret;
 446        SHA_CTX c;
 447
 448        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 449
 450        if (local < 0)
 451                return error("Couldn't open %s\n", filename);
 452
 453        memset(&stream, 0, sizeof(stream));
 454
 455        inflateInit(&stream);
 456
 457        SHA1_Init(&c);
 458
 459        do {
 460                ssize_t size;
 461                size = read(fd, buf, 4096);
 462                if (size <= 0) {
 463                        close(local);
 464                        unlink(filename);
 465                        if (!size)
 466                                return error("Connection closed?");
 467                        perror("Reading from connection");
 468                        return -1;
 469                }
 470                write(local, buf, size);
 471                stream.avail_in = size;
 472                stream.next_in = buf;
 473                do {
 474                        stream.next_out = discard;
 475                        stream.avail_out = sizeof(discard);
 476                        ret = inflate(&stream, Z_SYNC_FLUSH);
 477                        SHA1_Update(&c, discard, sizeof(discard) -
 478                                    stream.avail_out);
 479                } while (stream.avail_in && ret == Z_OK);
 480                
 481        } while (ret == Z_OK);
 482        inflateEnd(&stream);
 483
 484        close(local);
 485        SHA1_Final(real_sha1, &c);
 486        if (ret != Z_STREAM_END) {
 487                unlink(filename);
 488                return error("File %s corrupted", sha1_to_hex(sha1));
 489        }
 490        if (memcmp(sha1, real_sha1, 20)) {
 491                unlink(filename);
 492                return error("File %s has bad hash\n", sha1_to_hex(sha1));
 493        }
 494        
 495        return 0;
 496}
 497
 498int has_sha1_file(const unsigned char *sha1)
 499{
 500        char *filename = sha1_file_name(sha1);
 501        struct stat st;
 502
 503        if (!stat(filename, &st))
 504                return 1;
 505        return 0;
 506}