diff options
| -rw-r--r-- | Userland/Libraries/LibCompress/Xz.cpp | 94 | ||||
| -rw-r--r-- | Userland/Libraries/LibCompress/Xz.h | 1 |
2 files changed, 51 insertions, 44 deletions
diff --git a/Userland/Libraries/LibCompress/Xz.cpp b/Userland/Libraries/LibCompress/Xz.cpp index 29be32a233..b0a00c340e 100644 --- a/Userland/Libraries/LibCompress/Xz.cpp +++ b/Userland/Libraries/LibCompress/Xz.cpp @@ -252,6 +252,55 @@ ErrorOr<bool> XzDecompressor::load_next_stream() return true; } +ErrorOr<void> XzDecompressor::finish_current_block() +{ + auto unpadded_size = m_stream->read_bytes() - m_current_block_start_offset; + + // 3.3. Block Padding: + // "Block Padding MUST contain 0-3 null bytes to make the size of + // the Block a multiple of four bytes. This can be needed when + // the size of Compressed Data is not a multiple of four." + for (size_t i = 0; (unpadded_size + i) % 4 != 0; i++) { + auto padding_byte = TRY(m_stream->read_value<u8>()); + + // "If any of the bytes in Block Padding are not null bytes, the decoder + // MUST indicate an error." + if (padding_byte != 0) + return Error::from_string_literal("XZ block contains a non-null padding byte"); + } + + // 3.4. Check: + // "The type and size of the Check field depends on which bits + // are set in the Stream Flags field (see Section 2.1.1.2). + // + // The Check, when used, is calculated from the original + // uncompressed data. If the calculated Check does not match the + // stored one, the decoder MUST indicate an error. If the selected + // type of Check is not supported by the decoder, it SHOULD + // indicate a warning or error." + auto maybe_check_size = size_for_check_type(m_stream_flags->check_type); + + if (!maybe_check_size.has_value()) + return Error::from_string_literal("XZ stream has an unknown check type"); + + // TODO: Block content checks are currently unimplemented as a whole, independent of the check type. + // For now, we only make sure to remove the correct amount of bytes from the stream. + TRY(m_stream->discard(*maybe_check_size)); + unpadded_size += *maybe_check_size; + + if (m_current_block_expected_uncompressed_size.has_value()) { + if (*m_current_block_expected_uncompressed_size != m_current_block_uncompressed_size) + return Error::from_string_literal("Uncompressed size of XZ block does not match the expected value"); + } + + TRY(m_processed_blocks.try_append({ + .uncompressed_size = m_current_block_uncompressed_size, + .unpadded_size = unpadded_size, + })); + + return {}; +} + ErrorOr<Bytes> XzDecompressor::read_some(Bytes bytes) { if (!m_stream_flags.has_value()) { @@ -262,50 +311,7 @@ ErrorOr<Bytes> XzDecompressor::read_some(Bytes bytes) if (!m_current_block_stream.has_value() || (*m_current_block_stream)->is_eof()) { if (m_current_block_stream.has_value()) { // We have already processed a block, so we weed to clean up trailing data before the next block starts. - - auto unpadded_size = m_stream->read_bytes() - m_current_block_start_offset; - - // 3.3. Block Padding: - // "Block Padding MUST contain 0-3 null bytes to make the size of - // the Block a multiple of four bytes. This can be needed when - // the size of Compressed Data is not a multiple of four." - for (size_t i = 0; (unpadded_size + i) % 4 != 0; i++) { - auto padding_byte = TRY(m_stream->read_value<u8>()); - - // "If any of the bytes in Block Padding are not null bytes, the decoder - // MUST indicate an error." - if (padding_byte != 0) - return Error::from_string_literal("XZ block contains a non-null padding byte"); - } - - // 3.4. Check: - // "The type and size of the Check field depends on which bits - // are set in the Stream Flags field (see Section 2.1.1.2). - // - // The Check, when used, is calculated from the original - // uncompressed data. If the calculated Check does not match the - // stored one, the decoder MUST indicate an error. If the selected - // type of Check is not supported by the decoder, it SHOULD - // indicate a warning or error." - auto maybe_check_size = size_for_check_type(m_stream_flags->check_type); - - if (!maybe_check_size.has_value()) - return Error::from_string_literal("XZ stream has an unknown check type"); - - // TODO: Block content checks are currently unimplemented as a whole, independent of the check type. - // For now, we only make sure to remove the correct amount of bytes from the stream. - TRY(m_stream->discard(*maybe_check_size)); - unpadded_size += *maybe_check_size; - - if (m_current_block_expected_uncompressed_size.has_value()) { - if (*m_current_block_expected_uncompressed_size != m_current_block_uncompressed_size) - return Error::from_string_literal("Uncompressed size of XZ block does not match the expected value"); - } - - TRY(m_processed_blocks.try_append({ - .uncompressed_size = m_current_block_uncompressed_size, - .unpadded_size = unpadded_size, - })); + TRY(finish_current_block()); } auto start_of_current_block = m_stream->read_bytes(); diff --git a/Userland/Libraries/LibCompress/Xz.h b/Userland/Libraries/LibCompress/Xz.h index 5aad991cba..f9bc9b9a0a 100644 --- a/Userland/Libraries/LibCompress/Xz.h +++ b/Userland/Libraries/LibCompress/Xz.h @@ -112,6 +112,7 @@ private: XzDecompressor(NonnullOwnPtr<CountingStream>); ErrorOr<bool> load_next_stream(); + ErrorOr<void> finish_current_block(); NonnullOwnPtr<CountingStream> m_stream; Optional<XzStreamFlags> m_stream_flags; |