Figured out it was the filters for XZ that was causing problems

Added lzma and xz decompression.
Renamed Zlib to Gzip

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/gopherjs/gopherjs v0.0.0-20200217142428-fce0ec30dd00 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/smartystreets/assertions v1.2.0 // indirect
+	github.com/ulikunitz/xz v0.5.8
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 	gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776 // indirect

go.sum

@@ -38,6 +38,8 @@ github.com/smartystreets/goconvey v1.6.4/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/ulikunitz/xz v0.5.8 h1:ERv8V6GKqVi23rgu5cj9pVfVzJbOqAY2Ntl88O6c2nQ=
+github.com/ulikunitz/xz v0.5.8/go.mod h1:nbz6k7qbPmH4IRqmfOplQw/tblSgqTqBwxkY0oWt/14=
 go.lsp.dev/uri v0.3.0 h1:KcZJmh6nFIBeJzTugn5JTU6OOyG0lDOo3R9KwTxTYbo=
 go.lsp.dev/uri v0.3.0/go.mod h1:P5sbO1IQR+qySTWOCnhnK7phBx+W3zbLqSMDJNTw88I=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=

internal/compression/gzip.go

@@ -6,11 +6,11 @@ import (
 	"io"
 )
 
-//Zlib is a decompressor for gzip type compression
-type Zlib struct{}
+//Gzip is a decompressor for gzip type compression. Uses zlib for compression and decompression
+type Gzip struct{}
 
 //Decompress reads the entirety of the given reader and returns it uncompressed as a byte slice.
-func (z *Zlib) Decompress(r io.Reader) ([]byte, error) {
+func (g *Gzip) Decompress(r io.Reader) ([]byte, error) {
 	rdr, err := zlib.NewReader(r)
 	if err != nil {
 		return nil, err
@@ -24,7 +24,7 @@ func (z *Zlib) Decompress(r io.Reader) ([]byte, error) {
 }
 
 //Compress compresses the given data (as a byte array) and returns the compressed data.
-func (z *Zlib) Compress(data []byte) ([]byte, error) {
+func (g *Gzip) Compress(data []byte) ([]byte, error) {
 	var buf bytes.Buffer
 	wrt := zlib.NewWriter(&buf)
 	defer wrt.Close()

internal/compression/lzma.go

@@ -0,0 +1,25 @@
+package compression
+
+import (
+	"bytes"
+	"io"
+
+	"github.com/ulikunitz/xz/lzma"
+)
+
+//Lzma is a lzma decompressor
+type Lzma struct{}
+
+//Decompress decompresses all the data in the given reader and returns the uncompressed bytes.
+func (l *Lzma) Decompress(rdr io.Reader) ([]byte, error) {
+	r, err := lzma.NewReader(rdr)
+	if err != nil {
+		return nil, err
+	}
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, r)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}

internal/compression/xz.go

@@ -0,0 +1,55 @@
+package compression
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	"github.com/ulikunitz/xz"
+)
+
+type xzInit struct {
+	DictionarySize int32
+	Filters        int32
+}
+
+//Xz is a Xz decompressor.
+type Xz struct {
+	DictionarySize int32
+	HasFilters     bool
+}
+
+//NewXzCompressorWithOptions creates a new Xz compressor/decompressor that reads the compressor options from the given reader.
+func NewXzCompressorWithOptions(rdr io.Reader) (*Xz, error) {
+	var x Xz
+	var init xzInit
+	err := binary.Read(rdr, binary.LittleEndian, &init)
+	if err != nil {
+		return nil, err
+	}
+	x.DictionarySize = init.DictionarySize
+	//TODO: When I can do filters, parse the filters
+	if init.Filters != 0 {
+		x.HasFilters = true
+	}
+	return &x, nil
+}
+
+//Decompress decompresses all the data from the rdr and returns the uncompressed bytes.
+func (x *Xz) Decompress(rdr io.Reader) ([]byte, error) {
+	r, err := xz.NewReader(rdr)
+	if err != nil {
+		return nil, err
+	}
+	r.DictCap = int(x.DictionarySize)
+	err = r.Verify()
+	if err != nil {
+		return nil, err
+	}
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, r)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}

reader.go

@@ -50,23 +50,26 @@ func NewSquashfsReader(r io.ReaderAt) (*Reader, error) {
 	rdr.flags = rdr.super.GetFlags()
 	if rdr.flags.CompressorOptions {
 		switch rdr.super.CompressionType {
-		//Xzcompression isn't working right now.
-		// case xzCompression:
-		// 	xz, err := compression.NewXzWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 1000)) //1000 is technically too much, but it's just an easy way to do it.
-		// 	if err != nil {
-		// 		return nil, err
-		// 	}
-		// 	rdr.decompressor = xz
+		case xzCompression:
+			xz, err := compression.NewXzCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 1000)) //1000 is technically too much, but it's just an easy way to do it.
+			if err != nil {
+				return nil, err
+			}
+			if xz.HasFilters {
+				return nil, errors.New("XZ compression options has filters. These are not yet supported")
+			}
+			rdr.decompressor = xz
 		default:
 			return nil, errCompressorOptions
 		}
 	} else {
 		switch rdr.super.CompressionType {
 		case gzipCompression:
-			rdr.decompressor = &compression.Zlib{}
-			//Xzcompression isn't working right now.
-		// case xzCompression:
-		// 	rdr.decompressor = &compression.Xz{}
+			rdr.decompressor = &compression.Gzip{}
+		case lzmaCompression:
+			rdr.decompressor = &compression.Lzma{}
+		case xzCompression:
+			rdr.decompressor = &compression.Xz{}
 		default:
 			//TODO: all compression types.
 			return nil, errIncompatibleCompression