| 81 | } |
| 82 | |
| 83 | char *MD5FileChunk(const char *filename, char *buf, off_t ofs, off_t len) |
| 84 | { |
| 85 | unsigned char buffer[BUFSIZ]; |
| 86 | MD5_CTX ctx; |
| 87 | struct stat stbuf; |
| 88 | int f, i, e; |
| 89 | off_t n; |
| 90 | |
| 91 | MD5Init(&ctx); |
| 92 | #ifdef _WIN32 |
| 93 | f = _open(filename, O_RDONLY | O_BINARY); |
| 94 | #else |
| 95 | f = open(filename, O_RDONLY); |
| 96 | #endif |
| 97 | if (f < 0) |
| 98 | return 0; |
| 99 | if (fstat(f, &stbuf) < 0) |
| 100 | return 0; |
| 101 | if (ofs > stbuf.st_size) |
| 102 | ofs = stbuf.st_size; |
| 103 | if ((len == 0) || (len > stbuf.st_size - ofs)) |
| 104 | len = stbuf.st_size - ofs; |
| 105 | if (lseek(f, ofs, SEEK_SET) < 0) |
| 106 | return 0; |
| 107 | n = len; |
| 108 | i = 0; |
| 109 | while (n > 0) { |
| 110 | if (n > (off_t)sizeof(buffer)) |
| 111 | i = read(f, buffer, sizeof(buffer)); |
| 112 | else |
| 113 | i = read(f, buffer, n); |
| 114 | if (i < 0) |
| 115 | break; |
| 116 | MD5Update(&ctx, buffer, i); |
| 117 | n -= i; |
| 118 | } |
| 119 | e = errno; |
| 120 | close(f); |
| 121 | errno = e; |
| 122 | if (i < 0) |
| 123 | return 0; |
| 124 | return (MD5End(&ctx, buf)); |
| 125 | } |