Andrew's git - gitweb.git/blob

d91e072f3e5480de3605fb3f1e581a938301bdfb
   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
  63int get_sha1(const char *str, unsigned char *sha1)
  64{
  65        static char pathname[PATH_MAX];
  66
  67        if (!get_sha1_hex(str, sha1))
  68                return 0;
  69        if (!get_sha1_file(str, sha1))
  70                return 0;
  71        snprintf(pathname, sizeof(pathname), ".git/%s", str);
  72        if (!get_sha1_file(pathname, sha1))
  73                return 0;
  74        return -1;
  75}
  76
  77char * sha1_to_hex(const unsigned char *sha1)
  78{
  79        static char buffer[50];
  80        static const char hex[] = "0123456789abcdef";
  81        char *buf = buffer;
  82        int i;
  83
  84        for (i = 0; i < 20; i++) {
  85                unsigned int val = *sha1++;
  86                *buf++ = hex[val >> 4];
  87                *buf++ = hex[val & 0xf];
  88        }
  89        return buffer;
  90}
  91
  92/*
  93 * NOTE! This returns a statically allocated buffer, so you have to be
  94 * careful about using it. Do a "strdup()" if you need to save the
  95 * filename.
  96 */
  97char *sha1_file_name(const unsigned char *sha1)
  98{
  99        int i;
 100        static char *name, *base;
 101
 102        if (!base) {
 103                char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
 104                int len = strlen(sha1_file_directory);
 105                base = xmalloc(len + 60);
 106                memcpy(base, sha1_file_directory, len);
 107                memset(base+len, 0, 60);
 108                base[len] = '/';
 109                base[len+3] = '/';
 110                name = base + len + 1;
 111        }
 112        for (i = 0; i < 20; i++) {
 113                static char hex[] = "0123456789abcdef";
 114                unsigned int val = sha1[i];
 115                char *pos = name + i*2 + (i > 0);
 116                *pos++ = hex[val >> 4];
 117                *pos = hex[val & 0xf];
 118        }
 119        return base;
 120}
 121
 122int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 123{
 124        char header[100];
 125        unsigned char real_sha1[20];
 126        SHA_CTX c;
 127
 128        SHA1_Init(&c);
 129        SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 130        SHA1_Update(&c, map, size);
 131        SHA1_Final(real_sha1, &c);
 132        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 133}
 134
 135void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 136{
 137        char *filename = sha1_file_name(sha1);
 138        struct stat st;
 139        void *map;
 140        int fd;
 141
 142        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 143        if (fd < 0) {
 144                /* See if it works without O_NOATIME */
 145                switch (sha1_file_open_flag) {
 146                default:
 147                        fd = open(filename, O_RDONLY);
 148                        if (fd >= 0)
 149                                break;
 150                /* Fallthrough */
 151                case 0:
 152                        perror(filename);
 153                        return NULL;
 154                }
 155
 156                /* If it failed once, it will probably fail again. Stop using O_NOATIME */
 157                sha1_file_open_flag = 0;
 158        }
 159        if (fstat(fd, &st) < 0) {
 160                close(fd);
 161                return NULL;
 162        }
 163        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 164        close(fd);
 165        if (-1 == (int)(long)map)
 166                return NULL;
 167        *size = st.st_size;
 168        return map;
 169}
 170
 171void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 172{
 173        int ret, bytes;
 174        z_stream stream;
 175        char buffer[8192];
 176        char *buf;
 177
 178        /* Get the data stream */
 179        memset(&stream, 0, sizeof(stream));
 180        stream.next_in = map;
 181        stream.avail_in = mapsize;
 182        stream.next_out = buffer;
 183        stream.avail_out = sizeof(buffer);
 184
 185        inflateInit(&stream);
 186        ret = inflate(&stream, 0);
 187        if (ret < Z_OK)
 188                return NULL;
 189        if (sscanf(buffer, "%10s %lu", type, size) != 2)
 190                return NULL;
 191
 192        bytes = strlen(buffer) + 1;
 193        buf = xmalloc(*size);
 194
 195        memcpy(buf, buffer + bytes, stream.total_out - bytes);
 196        bytes = stream.total_out - bytes;
 197        if (bytes < *size && ret == Z_OK) {
 198                stream.next_out = buf + bytes;
 199                stream.avail_out = *size - bytes;
 200                while (inflate(&stream, Z_FINISH) == Z_OK)
 201                        /* nothing */;
 202        }
 203        inflateEnd(&stream);
 204        return buf;
 205}
 206
 207void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 208{
 209        unsigned long mapsize;
 210        void *map, *buf;
 211
 212        map = map_sha1_file(sha1, &mapsize);
 213        if (map) {
 214                buf = unpack_sha1_file(map, mapsize, type, size);
 215                munmap(map, mapsize);
 216                return buf;
 217        }
 218        return NULL;
 219}
 220
 221void *read_object_with_reference(const unsigned char *sha1,
 222                                 const unsigned char *required_type,
 223                                 unsigned long *size,
 224                                 unsigned char *actual_sha1_return)
 225{
 226        char type[20];
 227        void *buffer;
 228        unsigned long isize;
 229        unsigned char actual_sha1[20];
 230
 231        memcpy(actual_sha1, sha1, 20);
 232        while (1) {
 233                int ref_length = -1;
 234                const char *ref_type = NULL;
 235
 236                buffer = read_sha1_file(actual_sha1, type, &isize);
 237                if (!buffer)
 238                        return NULL;
 239                if (!strcmp(type, required_type)) {
 240                        *size = isize;
 241                        if (actual_sha1_return)
 242                                memcpy(actual_sha1_return, actual_sha1, 20);
 243                        return buffer;
 244                }
 245                /* Handle references */
 246                else if (!strcmp(type, "commit"))
 247                        ref_type = "tree ";
 248                else if (!strcmp(type, "tag"))
 249                        ref_type = "object ";
 250                else {
 251                        free(buffer);
 252                        return NULL;
 253                }
 254                ref_length = strlen(ref_type);
 255
 256                if (memcmp(buffer, ref_type, ref_length) ||
 257                    get_sha1_hex(buffer + ref_length, actual_sha1)) {
 258                        free(buffer);
 259                        return NULL;
 260                }
 261                /* Now we have the ID of the referred-to object in
 262                 * actual_sha1.  Check again. */
 263        }
 264}
 265
 266int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 267{
 268        int size;
 269        char *compressed;
 270        z_stream stream;
 271        unsigned char sha1[20];
 272        SHA_CTX c;
 273        char *filename;
 274        char hdr[50];
 275        int fd, hdrlen;
 276
 277        /* Generate the header */
 278        hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
 279
 280        /* Sha1.. */
 281        SHA1_Init(&c);
 282        SHA1_Update(&c, hdr, hdrlen);
 283        SHA1_Update(&c, buf, len);
 284        SHA1_Final(sha1, &c);
 285
 286        if (returnsha1)
 287                memcpy(returnsha1, sha1, 20);
 288
 289        filename = sha1_file_name(sha1);
 290        fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 291        if (fd < 0) {
 292                if (errno != EEXIST)
 293                        return -1;
 294
 295                /*
 296                 * We might do collision checking here, but we'd need to
 297                 * uncompress the old file and check it. Later.
 298                 */
 299                return 0;
 300        }
 301
 302        /* Set it up */
 303        memset(&stream, 0, sizeof(stream));
 304        deflateInit(&stream, Z_BEST_COMPRESSION);
 305        size = deflateBound(&stream, len+hdrlen);
 306        compressed = xmalloc(size);
 307
 308        /* Compress it */
 309        stream.next_out = compressed;
 310        stream.avail_out = size;
 311
 312        /* First header.. */
 313        stream.next_in = hdr;
 314        stream.avail_in = hdrlen;
 315        while (deflate(&stream, 0) == Z_OK)
 316                /* nothing */
 317
 318        /* Then the data itself.. */
 319        stream.next_in = buf;
 320        stream.avail_in = len;
 321        while (deflate(&stream, Z_FINISH) == Z_OK)
 322                /* nothing */;
 323        deflateEnd(&stream);
 324        size = stream.total_out;
 325
 326        if (write(fd, compressed, size) != size)
 327                die("unable to write file");
 328        close(fd);
 329                
 330        return 0;
 331}
 332
 333static inline int collision_check(char *filename, void *buf, unsigned int size)
 334{
 335#ifdef COLLISION_CHECK
 336        void *map;
 337        int fd = open(filename, O_RDONLY);
 338        struct stat st;
 339        int cmp;
 340
 341        /* Unreadable object, or object went away? Strange. */
 342        if (fd < 0)
 343                return -1;
 344
 345        if (fstat(fd, &st) < 0 || size != st.st_size)
 346                return -1;
 347
 348        map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 349        close(fd);
 350        if (map == MAP_FAILED)
 351                return -1;
 352        cmp = memcmp(buf, map, size);
 353        munmap(map, size);
 354        if (cmp)
 355                return -1;
 356#endif
 357        return 0;
 358}
 359
 360int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 361{
 362        char *filename = sha1_file_name(sha1);
 363        int fd;
 364
 365        fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 366        if (fd < 0) {
 367                if (errno != EEXIST)
 368                        return -1;
 369                if (collision_check(filename, buf, size))
 370                        return error("SHA1 collision detected!"
 371                                        " This is bad, bad, BAD!\a\n");
 372                return 0;
 373        }
 374        write(fd, buf, size);
 375        close(fd);
 376        return 0;
 377}
 378
 379int write_sha1_from_fd(const unsigned char *sha1, int fd)
 380{
 381        char *filename = sha1_file_name(sha1);
 382
 383        int local;
 384        z_stream stream;
 385        unsigned char real_sha1[20];
 386        char buf[4096];
 387        char discard[4096];
 388        int ret;
 389        SHA_CTX c;
 390
 391        local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 392
 393        if (local < 0)
 394                return error("Couldn't open %s\n", filename);
 395
 396        memset(&stream, 0, sizeof(stream));
 397
 398        inflateInit(&stream);
 399
 400        SHA1_Init(&c);
 401
 402        do {
 403                ssize_t size;
 404                size = read(fd, buf, 4096);
 405                if (size <= 0) {
 406                        close(local);
 407                        unlink(filename);
 408                        if (!size)
 409                                return error("Connection closed?");
 410                        perror("Reading from connection");
 411                        return -1;
 412                }
 413                write(local, buf, size);
 414                stream.avail_in = size;
 415                stream.next_in = buf;
 416                do {
 417                        stream.next_out = discard;
 418                        stream.avail_out = sizeof(discard);
 419                        ret = inflate(&stream, Z_SYNC_FLUSH);
 420                        SHA1_Update(&c, discard, sizeof(discard) -
 421                                    stream.avail_out);
 422                } while (stream.avail_in && ret == Z_OK);
 423                
 424        } while (ret == Z_OK);
 425        inflateEnd(&stream);
 426
 427        close(local);
 428        SHA1_Final(real_sha1, &c);
 429        if (ret != Z_STREAM_END) {
 430                unlink(filename);
 431                return error("File %s corrupted", sha1_to_hex(sha1));
 432        }
 433        if (memcmp(sha1, real_sha1, 20)) {
 434                unlink(filename);
 435                return error("File %s has bad hash\n", sha1_to_hex(sha1));
 436        }
 437        
 438        return 0;
 439}
 440
 441int has_sha1_file(const unsigned char *sha1)
 442{
 443        char *filename = sha1_file_name(sha1);
 444        struct stat st;
 445
 446        if (!stat(filename, &st))
 447                return 1;
 448        return 0;
 449}