diff options
Diffstat (limited to 'archival/libunarchive/get_header_tar.c')
| -rw-r--r-- | archival/libunarchive/get_header_tar.c | 111 |
1 files changed, 31 insertions, 80 deletions
diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c index adb4c15..fcddcb8 100644 --- a/archival/libunarchive/get_header_tar.c +++ b/archival/libunarchive/get_header_tar.c @@ -18,87 +18,45 @@ typedef uint32_t aliased_uint32_t FIX_ALIASING; typedef off_t aliased_off_t FIX_ALIASING; -/* - * GNU tar uses "base-256 encoding" for very large numbers (>8 billion). - * Encoding is binary, with highest bit always set as a marker - * and sign in next-highest bit: - * 80 00 .. 00 - zero - * bf ff .. ff - largest positive number - * ff ff .. ff - minus 1 - * c0 00 .. 00 - smallest negative number - * - * We expect it only in size field, where negative numbers don't make sense. - */ -static off_t getBase256_len12(const char *str) -{ - off_t value; - int len; - - /* if (*str & 0x40) error; - caller prevents this */ - - if (sizeof(off_t) >= 12) { - /* Probably 128-bit (16 byte) off_t. Can be optimized. */ - len = 12; - value = *str++ & 0x3f; - while (--len) - value = (value << 8) + (unsigned char) *str++; - return value; - } - -#ifdef CHECK_FOR_OVERFLOW - /* Can be optimized to eat 32-bit chunks */ - char c = *str++ & 0x3f; - len = 12; - while (1) { - if (c) - bb_error_msg_and_die("overflow in base-256 encoded file size"); - if (--len == sizeof(off_t)) - break; - c = *str++; - } -#else - str += (12 - sizeof(off_t)); -#endif - -/* Now str points to sizeof(off_t) least significant bytes. - * - * Example of tar file with 8914993153 (0x213600001) byte file. - * Field starts at offset 7c: - * 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....| - * 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336| - * - * str is at offset 80 or 84 now (64-bit or 32-bit off_t). - * We (ab)use the fact that value happens to be aligned, - * and fetch it in one go: - */ - if (sizeof(off_t) == 8) { - value = *(aliased_off_t*)str; - value = SWAP_BE64(value); - } else if (sizeof(off_t) == 4) { - value = *(aliased_off_t*)str; - value = SWAP_BE32(value); - } else { - value = 0; - len = sizeof(off_t); - while (--len) - value = (value << 8) + (unsigned char) *str++; - } - return value; -} - /* NB: _DESTROYS_ str[len] character! */ static unsigned long long getOctal(char *str, int len) { unsigned long long v; + char *end; /* NB: leading spaces are allowed. Using strtoull to handle that. * The downside is that we accept e.g. "-123" too :( */ str[len] = '\0'; - v = strtoull(str, &str, 8); + v = strtoull(str, &end, 8); /* std: "Each numeric field is terminated by one or more * <space> or NUL characters". We must support ' '! */ - if (*str != '\0' && *str != ' ') - bb_error_msg_and_die("corrupted octal value in tar header"); + if (*end != '\0' && *end != ' ') { + int8_t first = str[0]; + if (!(first & 0x80)) + bb_error_msg_and_die("corrupted octal value in tar header"); + /* + * GNU tar uses "base-256 encoding" for very large numbers. + * Encoding is binary, with highest bit always set as a marker + * and sign in next-highest bit: + * 80 00 .. 00 - zero + * bf ff .. ff - largest positive number + * ff ff .. ff - minus 1 + * c0 00 .. 00 - smallest negative number + * + * Example of tar file with 8914993153 (0x213600001) byte file. + * Field starts at offset 7c: + * 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....| + * 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336| + * + * NB: tarballs with NEGATIVE unix times encoded that way were seen! + */ + v = first; + /* Sign-extend using 6th bit: */ + v <<= sizeof(unsigned long long)*8 - 7; + v = (long long)v >> (sizeof(unsigned long long)*8 - 7); + while (--len != 0) + v = (v << 8) + (unsigned char) *str++; + } return v; } #define GET_OCTAL(a) getOctal((a), sizeof(a)) @@ -358,15 +316,8 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle) file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL; file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL; #endif - /* mtime: rudimentally handle GNU tar's "base256 encoding" - * People report tarballs with NEGATIVE unix times encoded that way */ - file_header->mtime = (tar.mtime[0] & 0x80) /* base256? */ - ? 0 /* bogus */ - : GET_OCTAL(tar.mtime); - /* size: handle GNU tar's "base256 encoding" */ - file_header->size = (tar.size[0] & 0xc0) == 0x80 /* positive base256? */ - ? getBase256_len12(tar.size) - : GET_OCTAL(tar.size); + file_header->mtime = GET_OCTAL(tar.mtime); + file_header->size = GET_OCTAL(tar.size); file_header->gid = GET_OCTAL(tar.gid); file_header->uid = GET_OCTAL(tar.uid); /* Set bits 0-11 of the files mode */ |