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authorDenys Vlasenko <vda.linux@googlemail.com>2010-05-06 18:08:14 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2010-05-06 18:08:14 (GMT)
commit7b48eb4372c0b639bcb1eaedd63795c2dc0d9820 (patch)
treef22da6d2d3ce82aa6d2c51cac27ab793cac4750d
parentc7efd6441def53df0200d7cce24e2956ad96aa02 (diff)
downloadbusybox-7b48eb4372c0b639bcb1eaedd63795c2dc0d9820.tar.gz
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tar: support GNU 256-bit encoding in all numeric fields
function old new delta getOctal 63 125 +62 get_header_tar 1572 1496 -76 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 62/-76) Total: -14 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--archival/libunarchive/get_header_tar.c111
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 */