lzma_block_compressed_size(lzma_block *block, lzma_vli unpadded_size)
{
// Validate everything but Uncompressed Size and filters.
if (lzma_block_unpadded_size(block) == 0)
return LZMA_PROG_ERROR;
const uint32_t container_size = block->header_size
+ lzma_check_size(block->check);
// Validate that Compressed Size will be greater than zero.
if (unpadded_size <= container_size)
return LZMA_DATA_ERROR;
// Calculate what Compressed Size is supposed to be.
// If Compressed Size was present in Block Header,
// compare that the new value matches it.
const lzma_vli compressed_size = unpadded_size - container_size;
if (block->compressed_size != LZMA_VLI_UNKNOWN
&& block->compressed_size != compressed_size)
return LZMA_DATA_ERROR;
block->compressed_size = compressed_size;
return LZMA_OK;
}
lzma_block_header_encode(const lzma_block *block, uint8_t *out)
{
// Validate everything but filters.
if (lzma_block_unpadded_size(block) == 0
|| !lzma_vli_is_valid(block->uncompressed_size))
return LZMA_PROG_ERROR;
// Indicate the size of the buffer _excluding_ the CRC32 field.
const size_t out_size = block->header_size - 4;
// Store the Block Header Size.
out[0] = out_size / 4;
// We write Block Flags in pieces.
out[1] = 0x00;
size_t out_pos = 2;
// Compressed Size
if (block->compressed_size != LZMA_VLI_UNKNOWN) {
return_if_error(lzma_vli_encode(block->compressed_size, NULL,
out, &out_pos, out_size));
out[1] |= 0x40;
}
// Uncompressed Size
if (block->uncompressed_size != LZMA_VLI_UNKNOWN) {
return_if_error(lzma_vli_encode(block->uncompressed_size, NULL,
out, &out_pos, out_size));
out[1] |= 0x80;
}
// Filter Flags
if (block->filters == NULL || block->filters[0].id == LZMA_VLI_UNKNOWN)
return LZMA_PROG_ERROR;
size_t filter_count = 0;
do {
// There can be a maximum of four filters.
if (filter_count == LZMA_FILTERS_MAX)
return LZMA_PROG_ERROR;
return_if_error(lzma_filter_flags_encode(
block->filters + filter_count,
out, &out_pos, out_size));
} while (block->filters[++filter_count].id != LZMA_VLI_UNKNOWN);
out[1] |= filter_count - 1;
// Padding
memzero(out + out_pos, out_size - out_pos);
// CRC32
unaligned_write32le(out + out_size, lzma_crc32(out, out_size, 0));
return LZMA_OK;
}
lzma_block_total_size(const lzma_block *block)
{
lzma_vli unpadded_size = lzma_block_unpadded_size(block);
if (unpadded_size != LZMA_VLI_UNKNOWN)
unpadded_size = vli_ceil4(unpadded_size);
return unpadded_size;
}
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;
}
lzma_stream_buffer_encode(lzma_filter *filters, lzma_check check,
lzma_allocator *allocator, const uint8_t *in, size_t in_size,
uint8_t *out, size_t *out_pos_ptr, size_t out_size)
{
// Sanity checks
if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX
|| (in == NULL && in_size != 0) || out == NULL
|| out_pos_ptr == NULL || *out_pos_ptr > out_size)
return LZMA_PROG_ERROR;
if (!lzma_check_is_supported(check))
return LZMA_UNSUPPORTED_CHECK;
// Note for the paranoids: Index encoder prevents the Stream from
// getting too big and still being accepted with LZMA_OK, and Block
// encoder catches if the input is too big. So we don't need to
// separately check if the buffers are too big.
// Use a local copy. We update *out_pos_ptr only if everything
// succeeds.
size_t out_pos = *out_pos_ptr;
// Check that there's enough space for both Stream Header and
// Stream Footer.
if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
return LZMA_BUF_ERROR;
// Reserve space for Stream Footer so we don't need to check for
// available space again before encoding Stream Footer.
out_size -= LZMA_STREAM_HEADER_SIZE;
// Encode the Stream Header.
lzma_stream_flags stream_flags = {
.version = 0,
.check = check,
};
if (lzma_stream_header_encode(&stream_flags, out + out_pos)
!= LZMA_OK)
return LZMA_PROG_ERROR;
out_pos += LZMA_STREAM_HEADER_SIZE;
// Encode a Block but only if there is at least one byte of input.
lzma_block block = {
.version = 0,
.check = check,
.filters = filters,
};
if (in_size > 0)
return_if_error(lzma_block_buffer_encode(&block, allocator,
in, in_size, out, &out_pos, out_size));
// Index
{
// Create an Index. It will have one Record if there was
// at least one byte of input to encode. Otherwise the
// Index will be empty.
lzma_index *i = lzma_index_init(allocator);
if (i == NULL)
return LZMA_MEM_ERROR;
lzma_ret ret = LZMA_OK;
if (in_size > 0)
ret = lzma_index_append(i, allocator,
lzma_block_unpadded_size(&block),
block.uncompressed_size);
// If adding the Record was successful, encode the Index
// and get its size which will be stored into Stream Footer.
if (ret == LZMA_OK) {
ret = lzma_index_buffer_encode(
i, out, &out_pos, out_size);
stream_flags.backward_size = lzma_index_size(i);
}
lzma_index_end(i, allocator);
if (ret != LZMA_OK)
return ret;
}
// Stream Footer. We have already reserved space for this.
if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
!= LZMA_OK)
return LZMA_PROG_ERROR;
out_pos += LZMA_STREAM_HEADER_SIZE;
// Everything went fine, make the new output position available
// to the application.
*out_pos_ptr = out_pos;
return LZMA_OK;
}
