7b48eb437
Denys Vlasenko
2010-05-06
Subject
tar: support GNU 256-bit encoding in all numeric fields
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archival/libunarchive/get_header_tar.c+31 -80
| @@ -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 */ | |