/*
* The extra data is stored as a list of
* id1+size1+data1 + id2+size2+data2 ...
* triplets. id and size are 2 bytes each.
*/
static void
process_extra(const void* extra, struct zip* zip)
{
int offset = 0;
const char *p = (const char *)extra;
while (offset < zip->extra_length - 4)
{
unsigned short headerid = archive_le16dec(p + offset);
unsigned short datasize = archive_le16dec(p + offset + 2);
offset += 4;
if (offset + datasize > zip->extra_length)
break;
#ifdef DEBUG
fprintf(stderr, "Header id 0x%04x, length %d\n",
headerid, datasize);
#endif
switch (headerid) {
case 0x0001:
/* Zip64 extended information extra field. */
if (datasize >= 8)
zip->uncompressed_size = archive_le64dec(p + offset);
if (datasize >= 16)
zip->compressed_size = archive_le64dec(p + offset + 8);
break;
case 0x5455:
{
/* Extended time field "UT". */
int flags = p[offset];
offset++;
datasize--;
/* Flag bits indicate which dates are present. */
if (flags & 0x01)
{
#ifdef DEBUG
fprintf(stderr, "mtime: %lld -> %d\n",
(long long)zip->mtime,
archive_le32dec(p + offset));
#endif
if (datasize < 4)
break;
zip->mtime = archive_le32dec(p + offset);
offset += 4;
datasize -= 4;
}
if (flags & 0x02)
{
if (datasize < 4)
break;
zip->atime = archive_le32dec(p + offset);
offset += 4;
datasize -= 4;
}
if (flags & 0x04)
{
if (datasize < 4)
break;
zip->ctime = archive_le32dec(p + offset);
offset += 4;
datasize -= 4;
}
break;
}
case 0x7855:
/* Info-ZIP Unix Extra Field (type 2) "Ux". */
#ifdef DEBUG
fprintf(stderr, "uid %d gid %d\n",
archive_le16dec(p + offset),
archive_le16dec(p + offset + 2));
#endif
if (datasize >= 2)
zip->uid = archive_le16dec(p + offset);
if (datasize >= 4)
zip->gid = archive_le16dec(p + offset + 2);
break;
default:
break;
}
offset += datasize;
}
#ifdef DEBUG
if (offset != zip->extra_length)
{
fprintf(stderr,
"Extra data field contents do not match reported size!");
}
#endif
}
/*
* Test whether we can handle this data.
*
* <sigh> LZMA has a rather poor file signature. Zeros do not
* make good signature bytes as a rule, and the only non-zero byte
* here is an ASCII character. For example, an uncompressed tar
* archive whose first file is ']' would satisfy this check. It may
* be necessary to exclude LZMA from compression_all() because of
* this. Clients of libarchive would then have to explicitly enable
* LZMA checking instead of (or in addition to) compression_all() when
* they have other evidence (file name, command-line option) to go on.
*/
static int
lzma_bidder_bid(struct archive_read_filter_bidder *self,
struct archive_read_filter *filter)
{
const unsigned char *buffer;
ssize_t avail;
uint32_t dicsize;
uint64_t uncompressed_size;
int bits_checked;
(void)self; /* UNUSED */
buffer = __archive_read_filter_ahead(filter, 14, &avail);
if (buffer == NULL)
return (0);
/* First byte of raw LZMA stream is commonly 0x5d.
* The first byte is a special number, which consists of
* three parameters of LZMA compression, a number of literal
* context bits(which is from 0 to 8, default is 3), a number
* of literal pos bits(which is from 0 to 4, default is 0),
* a number of pos bits(which is from 0 to 4, default is 2).
* The first byte is made by
* (pos bits * 5 + literal pos bit) * 9 + * literal contest bit,
* and so the default value in this field is
* (2 * 5 + 0) * 9 + 3 = 0x5d.
* lzma of LZMA SDK has options to change those parameters.
* It means a range of this field is from 0 to 224. And lzma of
* XZ Utils with option -e records 0x5e in this field. */
/* NOTE: If this checking of the first byte increases false
* recognition, we should allow only 0x5d and 0x5e for the first
* byte of LZMA stream. */
bits_checked = 0;
if (buffer[0] > (4 * 5 + 4) * 9 + 8)
return (0);
/* Most likely value in the first byte of LZMA stream. */
if (buffer[0] == 0x5d || buffer[0] == 0x5e)
bits_checked += 8;
/* Sixth through fourteenth bytes are uncompressed size,
* stored in little-endian order. `-1' means uncompressed
* size is unknown and lzma of XZ Utils always records `-1'
* in this field. */
uncompressed_size = archive_le64dec(buffer+5);
if (uncompressed_size == (uint64_t)ARCHIVE_LITERAL_LL(-1))
bits_checked += 64;
/* Second through fifth bytes are dictionary size, stored in
* little-endian order. The minimum dictionary size is
* 1 << 12(4KiB) which the lzma of LZMA SDK uses with option
* -d12 and the maxinam dictionary size is 1 << 27(128MiB)
* which the one uses with option -d27.
* NOTE: A comment of LZMA SDK source code says this dictionary
* range is from 1 << 12 to 1 << 30. */
dicsize = archive_le32dec(buffer+1);
switch (dicsize) {
case 0x00001000:/* lzma of LZMA SDK option -d12. */
case 0x00002000:/* lzma of LZMA SDK option -d13. */
case 0x00004000:/* lzma of LZMA SDK option -d14. */
case 0x00008000:/* lzma of LZMA SDK option -d15. */
case 0x00010000:/* lzma of XZ Utils option -0 and -1.
* lzma of LZMA SDK option -d16. */
case 0x00020000:/* lzma of LZMA SDK option -d17. */
case 0x00040000:/* lzma of LZMA SDK option -d18. */
case 0x00080000:/* lzma of XZ Utils option -2.
* lzma of LZMA SDK option -d19. */
case 0x00100000:/* lzma of XZ Utils option -3.
* lzma of LZMA SDK option -d20. */
case 0x00200000:/* lzma of XZ Utils option -4.
* lzma of LZMA SDK option -d21. */
case 0x00400000:/* lzma of XZ Utils option -5.
* lzma of LZMA SDK option -d22. */
case 0x00800000:/* lzma of XZ Utils option -6.
* lzma of LZMA SDK option -d23. */
case 0x01000000:/* lzma of XZ Utils option -7.
* lzma of LZMA SDK option -d24. */
case 0x02000000:/* lzma of XZ Utils option -8.
* lzma of LZMA SDK option -d25. */
case 0x04000000:/* lzma of XZ Utils option -9.
* lzma of LZMA SDK option -d26. */
case 0x08000000:/* lzma of LZMA SDK option -d27. */
bits_checked += 32;
break;
default:
/* If a memory usage for encoding was not enough on
* the platform where LZMA stream was made, lzma of
* XZ Utils automatically decreased the dictionary
* size to enough memory for encoding by 1Mi bytes
* (1 << 20).*/
if (dicsize <= 0x03F00000 && dicsize >= 0x00300000 &&
(dicsize & ((1 << 20)-1)) == 0 &&
bits_checked == 8 + 64) {
bits_checked += 32;
break;
}
/* Otherwise dictionary size is unlikely. But it is
* possible that someone makes lzma stream with
* liblzma/LZMA SDK in one's dictionary size. */
return (0);
}
/* TODO: The above test is still very weak. It would be
* good to do better. */
return (bits_checked);
}
