lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out)
{
assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic)
== LZMA_STREAM_HEADER_SIZE);
if (options->version != 0)
return LZMA_OPTIONS_ERROR;
// Backward Size
if (!is_backward_size_valid(options))
return LZMA_PROG_ERROR;
unaligned_write32le(out + 4, options->backward_size / 4 - 1);
// Stream Flags
if (stream_flags_encode(options, out + 2 * 4))
return LZMA_PROG_ERROR;
// CRC32
const uint32_t crc = lzma_crc32(
out + 4, 4 + LZMA_STREAM_FLAGS_SIZE, 0);
unaligned_write32le(out, crc);
// Magic
memcpy(out + 2 * 4 + LZMA_STREAM_FLAGS_SIZE,
lzma_footer_magic, sizeof(lzma_footer_magic));
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;
}
static void
test_decode_invalid(void)
{
known_flags.check = LZMA_CHECK_NONE;
known_flags.backward_size = 1024;
expect(lzma_stream_header_encode(&known_flags, buffer) == LZMA_OK);
// Test 1 (invalid Magic Bytes)
buffer[5] ^= 1;
succeed(test_header_decoder(LZMA_FORMAT_ERROR));
buffer[5] ^= 1;
// Test 2a (valid CRC32)
uint32_t crc = lzma_crc32(buffer + 6, 2, 0);
unaligned_write32le(buffer + 8, crc);
succeed(test_header_decoder(LZMA_OK));
// Test 2b (invalid Stream Flags with valid CRC32)
buffer[6] ^= 0x20;
crc = lzma_crc32(buffer + 6, 2, 0);
unaligned_write32le(buffer + 8, crc);
succeed(test_header_decoder(LZMA_OPTIONS_ERROR));
// Test 3 (invalid CRC32)
expect(lzma_stream_header_encode(&known_flags, buffer) == LZMA_OK);
buffer[9] ^= 1;
succeed(test_header_decoder(LZMA_DATA_ERROR));
// Test 4 (invalid Stream Flags with valid CRC32)
expect(lzma_stream_footer_encode(&known_flags, buffer) == LZMA_OK);
buffer[9] ^= 0x40;
crc = lzma_crc32(buffer + 4, 6, 0);
unaligned_write32le(buffer, crc);
succeed(test_footer_decoder(LZMA_OPTIONS_ERROR));
// Test 5 (invalid Magic Bytes)
expect(lzma_stream_footer_encode(&known_flags, buffer) == LZMA_OK);
buffer[11] ^= 1;
succeed(test_footer_decoder(LZMA_FORMAT_ERROR));
}
extern lzma_ret
lzma_simple_props_encode(const void *options, uint8_t *out)
{
const lzma_options_bcj *const opt = options;
// The default start offset is zero, so we don't need to store any
// options unless the start offset is non-zero.
if (opt == NULL || opt->start_offset == 0)
return LZMA_OK;
unaligned_write32le(out, opt->start_offset);
return LZMA_OK;
}
lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out)
{
assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE
+ 4 == LZMA_STREAM_HEADER_SIZE);
if (options->version != 0)
return LZMA_OPTIONS_ERROR;
// Magic
memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));
// Stream Flags
if (stream_flags_encode(options, out + sizeof(lzma_header_magic)))
return LZMA_PROG_ERROR;
// CRC32 of the Stream Header
const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic),
LZMA_STREAM_FLAGS_SIZE, 0);
unaligned_write32le(out + sizeof(lzma_header_magic)
+ LZMA_STREAM_FLAGS_SIZE, crc);
return LZMA_OK;
}
