LibCompress: Refactor gzip de/compressor using zlib

Author: https://github.com/devgianlu
Commit: 2baa7977a4
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3755
Reviewed-by: https://github.com/gmta ✅
Reviewed-by: https://github.com/trflynn89

Libraries/LibCompress/Gzip.cpp

@@ -1,267 +1,39 @@
 /*
  * Copyright (c) 2020-2022, the SerenityOS developers.
  * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ * Copyright (c) 2025, Altomani Gianluca <altomanigianluca@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <LibCompress/Gzip.h>
 
-#include <AK/BitStream.h>
+#include <zlib.h>
-#include <AK/MemoryStream.h>
-#include <AK/String.h>
-#include <LibCore/DateTime.h>
 
 namespace Compress {
 
-bool GzipDecompressor::is_likely_compressed(ReadonlyBytes bytes)
+ErrorOr<NonnullOwnPtr<GzipDecompressor>> GzipDecompressor::create(MaybeOwned<Stream> stream)
 {
-    return bytes.size() >= 2 && bytes[0] == gzip_magic_1 && bytes[1] == gzip_magic_2;
+    auto buffer = TRY(AK::FixedArray<u8>::create(16 * 1024));
-}
+    auto zstream = TRY(GenericZlibDecompressor::new_z_stream(MAX_WBITS | 16));
-
+    return adopt_nonnull_own_or_enomem(new (nothrow) GzipDecompressor(move(buffer), move(stream), zstream));
-bool BlockHeader::valid_magic_number() const
-{
-    return identification_1 == gzip_magic_1 && identification_2 == gzip_magic_2;
-}
-
-bool BlockHeader::supported_by_implementation() const
-{
-    if (compression_method != 0x08) {
-        // RFC 1952 does not define any compression methods other than deflate.
-        return false;
-    }
-
-    if (flags > Flags::MAX) {
-        // RFC 1952 does not define any more flags.
-        return false;
-    }
-
-    return true;
-}
-
-ErrorOr<NonnullOwnPtr<GzipDecompressor::Member>> GzipDecompressor::Member::construct(BlockHeader header, LittleEndianInputBitStream& stream)
-{
-    auto deflate_stream = TRY(DeflateDecompressor::construct(MaybeOwned<LittleEndianInputBitStream>(stream)));
-    return TRY(adopt_nonnull_own_or_enomem(new (nothrow) Member(header, move(deflate_stream))));
-}
-
-GzipDecompressor::Member::Member(BlockHeader header, NonnullOwnPtr<DeflateDecompressor> stream)
-    : m_header(header)
-    , m_stream(move(stream))
-{
-}
-
-GzipDecompressor::GzipDecompressor(MaybeOwned<Stream> stream)
-    : m_input_stream(make<LittleEndianInputBitStream>(move(stream)))
-{
-}
-
-GzipDecompressor::~GzipDecompressor()
-{
-    m_current_member.clear();
-}
-
-ErrorOr<Bytes> GzipDecompressor::read_some(Bytes bytes)
-{
-    size_t total_read = 0;
-    while (total_read < bytes.size()) {
-        if (is_eof())
-            break;
-
-        auto slice = bytes.slice(total_read);
-
-        if (m_current_member) {
-            auto current_slice = TRY(current_member().m_stream->read_some(slice));
-            current_member().m_checksum.update(current_slice);
-            current_member().m_nread += current_slice.size();
-
-            if (current_slice.size() < slice.size()) {
-                u32 crc32 = TRY(m_input_stream->read_value<LittleEndian<u32>>());
-                u32 input_size = TRY(m_input_stream->read_value<LittleEndian<u32>>());
-
-                if (crc32 != current_member().m_checksum.digest())
-                    return Error::from_string_literal("Stored CRC32 does not match the calculated CRC32 of the current member");
-
-                if (input_size != current_member().m_nread)
-                    return Error::from_string_literal("Input size does not match the number of read bytes");
-
-                m_current_member.clear();
-
-                total_read += current_slice.size();
-                continue;
-            }
-
-            total_read += current_slice.size();
-            continue;
-        } else {
-            auto current_partial_header_slice = Bytes { m_partial_header, sizeof(BlockHeader) }.slice(m_partial_header_offset);
-            auto current_partial_header_data = TRY(m_input_stream->read_some(current_partial_header_slice));
-            m_partial_header_offset += current_partial_header_data.size();
-
-            if (is_eof())
-                break;
-
-            if (m_partial_header_offset < sizeof(BlockHeader)) {
-                break; // partial header read
-            }
-            m_partial_header_offset = 0;
-
-            BlockHeader header = *(reinterpret_cast<BlockHeader*>(m_partial_header));
-
-            if (!header.valid_magic_number())
-                return Error::from_string_literal("Header does not have a valid magic number");
-
-            if (!header.supported_by_implementation())
-                return Error::from_string_literal("Header is not supported by implementation");
-
-            if (header.flags & Flags::FEXTRA) {
-                u16 subfield_id = TRY(m_input_stream->read_value<LittleEndian<u16>>());
-                u16 length = TRY(m_input_stream->read_value<LittleEndian<u16>>());
-                TRY(m_input_stream->discard(length));
-                (void)subfield_id;
-            }
-
-            auto discard_string = [&]() -> ErrorOr<void> {
-                char next_char;
-                do {
-                    next_char = TRY(m_input_stream->read_value<char>());
-                } while (next_char);
-
-                return {};
-            };
-
-            if (header.flags & Flags::FNAME)
-                TRY(discard_string());
-
-            if (header.flags & Flags::FCOMMENT)
-                TRY(discard_string());
-
-            if (header.flags & Flags::FHCRC) {
-                u16 crc = TRY(m_input_stream->read_value<LittleEndian<u16>>());
-                // FIXME: we should probably verify this instead of just assuming it matches
-                (void)crc;
-            }
-
-            m_current_member = TRY(Member::construct(header, *m_input_stream));
-            continue;
-        }
-    }
-    return bytes.slice(0, total_read);
-}
-
-ErrorOr<Optional<String>> GzipDecompressor::describe_header(ReadonlyBytes bytes)
-{
-    if (bytes.size() < sizeof(BlockHeader))
-        return OptionalNone {};
-
-    auto& header = *(reinterpret_cast<BlockHeader const*>(bytes.data()));
-    if (!header.valid_magic_number() || !header.supported_by_implementation())
-        return OptionalNone {};
-
-    LittleEndian<u32> original_size = *reinterpret_cast<u32 const*>(bytes.offset(bytes.size() - sizeof(u32)));
-    return TRY(String::formatted("last modified: {}, original size {}", Core::DateTime::from_timestamp(header.modification_time), (u32)original_size));
 }
 
 ErrorOr<ByteBuffer> GzipDecompressor::decompress_all(ReadonlyBytes bytes)
 {
-    auto memory_stream = TRY(try_make<FixedMemoryStream>(bytes));
+    return ::Compress::decompress_all<GzipDecompressor>(bytes);
-    auto gzip_stream = make<GzipDecompressor>(move(memory_stream));
-    AllocatingMemoryStream output_stream;
-
-    auto buffer = TRY(ByteBuffer::create_uninitialized(4096));
-    while (!gzip_stream->is_eof()) {
-        auto const data = TRY(gzip_stream->read_some(buffer));
-        TRY(output_stream.write_until_depleted(data));
-    }
-
-    auto output_buffer = TRY(ByteBuffer::create_uninitialized(output_stream.used_buffer_size()));
-    TRY(output_stream.read_until_filled(output_buffer));
-    return output_buffer;
 }
 
-bool GzipDecompressor::is_eof() const { return m_input_stream->is_eof(); }
+ErrorOr<NonnullOwnPtr<GzipCompressor>> GzipCompressor::create(MaybeOwned<Stream> stream, GenericZlibCompressionLevel compression_level)
-
-ErrorOr<size_t> GzipDecompressor::write_some(ReadonlyBytes)
 {
-    return Error::from_errno(EBADF);
+    auto buffer = TRY(AK::FixedArray<u8>::create(16 * 1024));
+    auto zstream = TRY(GenericZlibCompressor::new_z_stream(MAX_WBITS | 16, compression_level));
+    return adopt_nonnull_own_or_enomem(new (nothrow) GzipCompressor(move(buffer), move(stream), zstream));
 }
 
-ErrorOr<NonnullOwnPtr<GzipCompressor>> GzipCompressor::create(MaybeOwned<Stream> output_stream)
+ErrorOr<ByteBuffer> GzipCompressor::compress_all(ReadonlyBytes bytes, GenericZlibCompressionLevel compression_level)
 {
-    BlockHeader header;
+    return ::Compress::compress_all<GzipCompressor>(bytes, compression_level);
-    header.identification_1 = 0x1f;
-    header.identification_2 = 0x8b;
-    header.compression_method = 0x08;
-    header.flags = 0;
-    header.modification_time = 0;
-    header.extra_flags = 3;      // DEFLATE sets 2 for maximum compression and 4 for minimum compression
-    header.operating_system = 3; // unix
-    TRY(output_stream->write_until_depleted({ &header, sizeof(header) }));
-
-    auto deflate_compressor = TRY(DeflateCompressor::construct(MaybeOwned(*output_stream)));
-    return adopt_own(*new GzipCompressor { move(output_stream), move(deflate_compressor) });
-}
-
-GzipCompressor::GzipCompressor(MaybeOwned<Stream> output_stream, NonnullOwnPtr<DeflateCompressor> deflate_compressor)
-    : m_output_stream(move(output_stream))
-    , m_deflate_compressor(move(deflate_compressor))
-{
-}
-
-ErrorOr<Bytes> GzipCompressor::read_some(Bytes)
-{
-    return Error::from_errno(EBADF);
-}
-
-ErrorOr<size_t> GzipCompressor::write_some(ReadonlyBytes bytes)
-{
-    VERIFY(!m_finished);
-
-    TRY(m_deflate_compressor->write_until_depleted(bytes));
-    m_total_bytes += bytes.size();
-    m_crc32.update(bytes);
-
-    return bytes.size();
-}
-
-ErrorOr<void> GzipCompressor::finish()
-{
-    VERIFY(!m_finished);
-    m_finished = true;
-
-    TRY(m_deflate_compressor->final_flush());
-    TRY(m_output_stream->write_value<LittleEndian<u32>>(m_crc32.digest()));
-    TRY(m_output_stream->write_value<LittleEndian<u32>>(m_total_bytes));
-
-    return {};
-}
-
-bool GzipCompressor::is_eof() const
-{
-    return true;
-}
-
-bool GzipCompressor::is_open() const
-{
-    return m_output_stream->is_open();
-}
-
-void GzipCompressor::close()
-{
-}
-
-ErrorOr<ByteBuffer> GzipCompressor::compress_all(ReadonlyBytes bytes)
-{
-    auto output_stream = TRY(try_make<AllocatingMemoryStream>());
-    auto gzip_stream = TRY(GzipCompressor::create(MaybeOwned { *output_stream }));
-
-    TRY(gzip_stream->write_until_depleted(bytes));
-    TRY(gzip_stream->finish());
-
-    auto buffer = TRY(ByteBuffer::create_uninitialized(output_stream->used_buffer_size()));
-    TRY(output_stream->read_until_filled(buffer.bytes()));
-
-    return buffer;
 }
 
 }

Libraries/LibCompress/Gzip.h

@@ -1,109 +1,41 @@
 /*
  * Copyright (c) 2020-2022, the SerenityOS developers.
  * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ * Copyright (c) 2025, Altomani Gianluca <altomanigianluca@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
-#include <AK/NonnullOwnPtr.h>
+#include <LibCompress/Zlib.h>
-#include <AK/OwnPtr.h>
-#include <AK/Stream.h>
-#include <LibCompress/Deflate.h>
-#include <LibCrypto/Checksum/CRC32.h>
 
 namespace Compress {
 
-constexpr u8 gzip_magic_1 = 0x1f;
+class GzipDecompressor final : public GenericZlibDecompressor {
-constexpr u8 gzip_magic_2 = 0x8b;
-struct [[gnu::packed]] BlockHeader {
-    u8 identification_1;
-    u8 identification_2;
-    u8 compression_method;
-    u8 flags;
-    LittleEndian<u32> modification_time;
-    u8 extra_flags;
-    u8 operating_system;
-
-    bool valid_magic_number() const;
-    bool supported_by_implementation() const;
-};
-
-struct Flags {
-    static constexpr u8 FTEXT = 1 << 0;
-    static constexpr u8 FHCRC = 1 << 1;
-    static constexpr u8 FEXTRA = 1 << 2;
-    static constexpr u8 FNAME = 1 << 3;
-    static constexpr u8 FCOMMENT = 1 << 4;
-
-    static constexpr u8 MAX = FTEXT | FHCRC | FEXTRA | FNAME | FCOMMENT;
-};
-
-class GzipDecompressor final : public Stream {
 public:
-    GzipDecompressor(MaybeOwned<Stream>);
+    bool is_likely_compressed(ReadonlyBytes bytes);
-    ~GzipDecompressor();
-
-    virtual ErrorOr<Bytes> read_some(Bytes) override;
-    virtual ErrorOr<size_t> write_some(ReadonlyBytes) override;
-    virtual bool is_eof() const override;
-    virtual bool is_open() const override { return true; }
-    virtual void close() override { }
 
+    static ErrorOr<NonnullOwnPtr<GzipDecompressor>> create(MaybeOwned<Stream>);
     static ErrorOr<ByteBuffer> decompress_all(ReadonlyBytes);
 
-    static ErrorOr<Optional<String>> describe_header(ReadonlyBytes);
-    static bool is_likely_compressed(ReadonlyBytes bytes);
-
 private:
-    class Member {
+    GzipDecompressor(AK::FixedArray<u8> buffer, MaybeOwned<Stream> stream, z_stream* zstream)
-    public:
+        : GenericZlibDecompressor(move(buffer), move(stream), zstream)
-        static ErrorOr<NonnullOwnPtr<Member>> construct(BlockHeader header, LittleEndianInputBitStream&);
+    {
-
+    }
-        BlockHeader m_header;
-        NonnullOwnPtr<DeflateDecompressor> m_stream;
-        Crypto::Checksum::CRC32 m_checksum;
-        size_t m_nread { 0 };
-
-    private:
-        Member(BlockHeader, NonnullOwnPtr<DeflateDecompressor>);
-    };
-
-    Member const& current_member() const { return *m_current_member; }
-    Member& current_member() { return *m_current_member; }
-
-    NonnullOwnPtr<LittleEndianInputBitStream> m_input_stream;
-    u8 m_partial_header[sizeof(BlockHeader)];
-    size_t m_partial_header_offset { 0 };
-    OwnPtr<Member> m_current_member {};
-
-    bool m_eof { false };
 };
 
-class GzipCompressor final : public Stream {
+class GzipCompressor final : public GenericZlibCompressor {
 public:
-    static ErrorOr<NonnullOwnPtr<GzipCompressor>> create(MaybeOwned<Stream>);
+    static ErrorOr<NonnullOwnPtr<GzipCompressor>> create(MaybeOwned<Stream>, GenericZlibCompressionLevel = GenericZlibCompressionLevel::Default);
-
+    static ErrorOr<ByteBuffer> compress_all(ReadonlyBytes, GenericZlibCompressionLevel = GenericZlibCompressionLevel::Default);
-    virtual ErrorOr<Bytes> read_some(Bytes) override;
-    virtual ErrorOr<size_t> write_some(ReadonlyBytes) override;
-    virtual bool is_eof() const override;
-    virtual bool is_open() const override;
-    virtual void close() override;
-
-    static ErrorOr<ByteBuffer> compress_all(ReadonlyBytes bytes);
-
-    ErrorOr<void> finish();
 
 private:
-    GzipCompressor(MaybeOwned<Stream>, NonnullOwnPtr<DeflateCompressor>);
+    GzipCompressor(AK::FixedArray<u8> buffer, MaybeOwned<Stream> stream, z_stream* zstream)
-
+        : GenericZlibCompressor(move(buffer), move(stream), zstream)
-    MaybeOwned<Stream> m_output_stream;
+    {
-    NonnullOwnPtr<DeflateCompressor> m_deflate_compressor;
+    }
-
-    Crypto::Checksum::CRC32 m_crc32;
-    size_t m_total_bytes { 0 };
-    bool m_finished { false };
 };
 
 }

Libraries/LibWeb/Compression/DecompressionStream.cpp

@@ -36,7 +36,7 @@ WebIDL::ExceptionOr<GC::Ref<DecompressionStream>> DecompressionStream::construct
         case Bindings::CompressionFormat::DeflateRaw:
             return TRY(Compress::DeflateDecompressor::construct(make<LittleEndianInputBitStream>(move(input_stream))));
         case Bindings::CompressionFormat::Gzip:
-            return make<Compress::GzipDecompressor>(move(input_stream));
+            return TRY(Compress::GzipDecompressor::create((move(input_stream))));
         }
 
         VERIFY_NOT_REACHED();

Tests/LibCompress/TestGzip.cpp

@@ -4,11 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <LibTest/TestCase.h>
-
-#include <AK/Array.h>
-#include <AK/Random.h>
 #include <LibCompress/Gzip.h>
+#include <LibTest/TestCase.h>
 
 TEST_CASE(gzip_decompress_simple)
 {
@@ -20,8 +17,8 @@ TEST_CASE(gzip_decompress_simple)
 
     u8 const uncompressed[] = "word1 abc word2";
 
-    auto const decompressed = Compress::GzipDecompressor::decompress_all(compressed);
+    auto const decompressed = TRY_OR_FAIL(Compress::GzipDecompressor::decompress_all(compressed));
-    EXPECT(decompressed.value().bytes() == (ReadonlyBytes { uncompressed, sizeof(uncompressed) - 1 }));
+    EXPECT(decompressed.bytes() == (ReadonlyBytes { uncompressed, sizeof(uncompressed) - 1 }));
 }
 
 TEST_CASE(gzip_decompress_multiple_members)
@@ -36,8 +33,8 @@ TEST_CASE(gzip_decompress_multiple_members)
 
     u8 const uncompressed[] = "abcabcabcabc";
 
-    auto const decompressed = Compress::GzipDecompressor::decompress_all(compressed);
+    auto const decompressed = TRY_OR_FAIL(Compress::GzipDecompressor::decompress_all(compressed));
-    EXPECT(decompressed.value().bytes() == (ReadonlyBytes { uncompressed, sizeof(uncompressed) - 1 }));
+    EXPECT(decompressed.bytes() == (ReadonlyBytes { uncompressed, sizeof(uncompressed) - 1 }));
 }
 
 TEST_CASE(gzip_decompress_zeroes)
@@ -61,8 +58,8 @@ TEST_CASE(gzip_decompress_zeroes)
 
     Array<u8, 128 * 1024> const uncompressed = { 0 };
 
-    auto const decompressed = Compress::GzipDecompressor::decompress_all(compressed);
+    auto const decompressed = TRY_OR_FAIL(Compress::GzipDecompressor::decompress_all(compressed));
-    EXPECT(uncompressed == decompressed.value().bytes());
+    EXPECT(uncompressed == decompressed.bytes());
 }
 
 TEST_CASE(gzip_decompress_repeat_around_buffer)
@@ -81,8 +78,8 @@ TEST_CASE(gzip_decompress_repeat_around_buffer)
     uncompressed.span().slice(0x0100, 0x7e00).fill(0);
     uncompressed.span().slice(0x7f00, 0x0100).fill(1);
 
-    auto const decompressed = Compress::GzipDecompressor::decompress_all(compressed);
+    auto const decompressed = TRY_OR_FAIL(Compress::GzipDecompressor::decompress_all(compressed));
-    EXPECT(uncompressed == decompressed.value().bytes());
+    EXPECT(uncompressed == decompressed.bytes());
 }
 
 TEST_CASE(gzip_round_trip)