lzma_filter_flags_decode(
lzma_filter *filter, lzma_allocator *allocator,
const uint8_t *in, size_t *in_pos, size_t in_size)
{
lzma_vli props_size;
lzma_ret ret;
// Set the pointer to NULL so the caller can always safely free it.
filter->options = NULL;
// Filter ID
return_if_error(lzma_vli_decode(&filter->id, NULL,
in, in_pos, in_size));
if (filter->id >= LZMA_FILTER_RESERVED_START)
return LZMA_DATA_ERROR;
// Size of Properties
return_if_error(lzma_vli_decode(&props_size, NULL,
in, in_pos, in_size));
// Filter Properties
if (in_size - *in_pos < props_size)
return LZMA_DATA_ERROR;
ret = lzma_properties_decode(
filter, allocator, in + *in_pos, props_size);
*in_pos += props_size;
return ret;
}
lzma_block_header_decode(lzma_block *block,
lzma_allocator *allocator, const uint8_t *in)
{
const size_t filter_count = (in[1] & 3) + 1;
size_t in_size;
size_t i;
// Start after the Block Header Size and Block Flags fields.
size_t in_pos = 2;
// NOTE: We consider the header to be corrupt not only when the
// CRC32 doesn't match, but also when variable-length integers
// are invalid or over 63 bits, or if the header is too small
// to contain the claimed information.
// Initialize the filter options array. This way the caller can
// safely free() the options even if an error occurs in this function.
for (i = 0; i <= LZMA_FILTERS_MAX; ++i) {
block->filters[i].id = LZMA_VLI_UNKNOWN;
block->filters[i].options = NULL;
}
// Always zero for now.
block->version = 0;
// Validate Block Header Size and Check type. The caller must have
// already set these, so it is a programming error if this test fails.
if (lzma_block_header_size_decode(in[0]) != block->header_size
|| (unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
return LZMA_PROG_ERROR;
// Exclude the CRC32 field.
in_size = block->header_size - 4;
// Verify CRC32
if (lzma_crc32(in, in_size, 0) != unaligned_read32le(in + in_size))
return LZMA_DATA_ERROR;
// Check for unsupported flags.
if (in[1] & 0x3C)
return LZMA_OPTIONS_ERROR;
// Compressed Size
if (in[1] & 0x40) {
return_if_error(lzma_vli_decode(&block->compressed_size,
NULL, in, &in_pos, in_size));
// Validate Compressed Size. This checks that it isn't zero
// and that the total size of the Block is a valid VLI.
if (lzma_block_unpadded_size(block) == 0)
return LZMA_DATA_ERROR;
} else {
block->compressed_size = LZMA_VLI_UNKNOWN;
}
// Uncompressed Size
if (in[1] & 0x80)
return_if_error(lzma_vli_decode(&block->uncompressed_size,
NULL, in, &in_pos, in_size));
else
block->uncompressed_size = LZMA_VLI_UNKNOWN;
// Filter Flags
for (i = 0; i < filter_count; ++i) {
const lzma_ret ret = lzma_filter_flags_decode(
&block->filters[i], allocator,
in, &in_pos, in_size);
if (ret != LZMA_OK) {
free_properties(block, allocator);
return ret;
}
}
// Padding
while (in_pos < in_size) {
if (in[in_pos++] != 0x00) {
free_properties(block, allocator);
// Possibly some new field present so use
// LZMA_OPTIONS_ERROR instead of LZMA_DATA_ERROR.
return LZMA_OPTIONS_ERROR;
}
}
return LZMA_OK;
}