Implemented the rest of the compression types

Haven't implemented LZO due to limited libraries

internal/compression/gzip.go

@@ -3,11 +3,37 @@ package compression
 import (
 	"bytes"
 	"compress/zlib"
+	"encoding/binary"
 	"io"
 )
 
+type gzipInit struct {
+	CompressionLevel int32
+	WindowSize       int16
+	Strategies       int16
+}
+
 //Gzip is a decompressor for gzip type compression. Uses zlib for compression and decompression
-type Gzip struct{}
+type Gzip struct {
+	CompressionLevel int32
+	HasCustomWindow  bool
+	HasStrategies    bool
+}
+
+//NewGzipCompressorWithOptions creates a new gzip compressor/decompressor with options read from the given reader.
+func NewGzipCompressorWithOptions(r io.Reader) (*Gzip, error) {
+	var gzip Gzip
+	var init gzipInit
+	err := binary.Read(r, binary.LittleEndian, &init)
+	if err != nil {
+		return nil, err
+	}
+	gzip.CompressionLevel = init.CompressionLevel
+	//TODO: proper support for window size and strategies
+	gzip.HasCustomWindow = init.WindowSize != 15
+	gzip.HasStrategies = init.Strategies != 0 && init.Strategies != 1
+	return &gzip, nil
+}
 
 //Decompress reads the entirety of the given reader and returns it uncompressed as a byte slice.
 func (g *Gzip) Decompress(r io.Reader) ([]byte, error) {

internal/compression/lz4.go

@@ -0,0 +1,37 @@
+package compression
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	"github.com/pierrec/lz4/v4"
+)
+
+//Lz4 is a Lz4 Compressor/Decompressor
+type Lz4 struct {
+	HC bool
+}
+
+//NewLz4CompressorWithOptions creates a new lz4 compressor/decompressor with options read from the given reader.
+func NewLz4CompressorWithOptions(r io.Reader) (*Lz4, error) {
+	var lz4 Lz4
+	var init struct {
+		Version int32
+		Flags   int32
+	}
+	err := binary.Read(r, binary.LittleEndian, &init)
+	if err != nil {
+		return nil, err
+	}
+	lz4.HC = init.Flags == 1
+	return &lz4, nil
+}
+
+//Decompress decompresses all data from r and returns the uncompressed bytes
+func (l *Lz4) Decompress(r io.Reader) ([]byte, error) {
+	rdr := lz4.NewReader(r)
+	var buf bytes.Buffer
+	_, err := io.Copy(&buf, rdr)
+	return buf.Bytes(), err
+}

internal/compression/zstd.go

@@ -0,0 +1,36 @@
+package compression
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	"github.com/klauspost/compress/zstd"
+)
+
+//Zstd is a zstd compressor/decompressor
+type Zstd struct {
+	CompressionLevel int32
+}
+
+//NewZstdCompressorWithOptions creates a new Zstd with options read from the given reader
+func NewZstdCompressorWithOptions(r io.Reader) (*Zstd, error) {
+	var zstd Zstd
+	err := binary.Read(r, binary.LittleEndian, &zstd)
+	if err != nil {
+		return nil, err
+	}
+	return &zstd, nil
+}
+
+//Decompress decompresses all data from the reader and returns the uncompressed data
+func (z *Zstd) Decompress(r io.Reader) ([]byte, error) {
+	rdr, err := zstd.NewReader(r)
+	if err != nil {
+		return nil, err
+	}
+	defer rdr.Close()
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, rdr)
+	return buf.Bytes(), err
+}