Change no_lzma and no_lzo to no_obsolete and no_gpl

Added build tags section to README

README.md

@@ -11,6 +11,10 @@ Currently has support for reading squashfs files and extracting files and folder
 Special thanks to <https://dr-emann.github.io/squashfs/> for some VERY important information in an easy to understand format.
 Thanks also to [distri's squashfs library](https://github.com/distr1/distri/tree/master/internal/squashfs) as I referenced it to figure some things out (and double check others).
 
+## Build tags
+
+This library has two optional build tags. `no_gpl` disables the ability to read archives with lzo compression due to the library's gpl license. `no_obsolete` removes "obsolete" compression types for a reduced size; currently this only disable lzma compression.
+
 ## FUSE
 
 As of `v1.0`, FUSE capabilities has been moved to [a separate library](https://github.com/CalebQ42/squashfuse).

internal/decompress/get_decomp.go

@@ -0,0 +1,32 @@
+package decompress
+
+import "errors"
+
+// The types of compression supported by squashfs
+const (
+	ZlibCompression = uint16(iota + 1)
+	LZMACompression
+	LZOCompression
+	XZCompression
+	LZ4Compression
+	ZSTDCompression
+)
+
+func GetDecompressor(compType uint16) (Decompressor, error) {
+	switch compType {
+	case ZlibCompression:
+		return Zlib{}, nil
+	case LZMACompression:
+		return Lzma{}, nil
+	case LZOCompression:
+		return Lzo{}, nil
+	case XZCompression:
+		return Xz{}, nil
+	case LZ4Compression:
+		return Lz4{}, nil
+	case ZSTDCompression:
+		return &Zstd{}, nil
+	default:
+		return nil, errors.New("invalid compression type. possible corrupted archive")
+	}
+}

internal/decompress/get_decomp_no_gpl.go

@@ -0,0 +1,34 @@
+//go:build no_gpl
+
+package decompress
+
+import "errors"
+
+// The types of compression supported by squashfs
+const (
+	ZlibCompression = uint16(iota + 1)
+	LZMACompression
+	LZOCompression
+	XZCompression
+	LZ4Compression
+	ZSTDCompression
+)
+
+func GetDecompressor(compType uint16) (Decompressor, error) {
+	switch compType {
+	case ZlibCompression:
+		return Zlib{}, nil
+	case LZMACompression:
+		return Lzma{}, nil
+	case LZOCompression:
+		return nil, errors.New("lzo compression is disable in this build with no_gpl")
+	case XZCompression:
+		return Xz{}, nil
+	case LZ4Compression:
+		return Lz4{}, nil
+	case ZSTDCompression:
+		return &Zstd{}, nil
+	default:
+		return nil, errors.New("invalid compression type. possible corrupted archive")
+	}
+}

internal/decompress/get_decomp_no_gpl_obsolete.go

@@ -0,0 +1,34 @@
+//go:build no_obsolete
+
+package decompress
+
+import "errors"
+
+// The types of compression supported by squashfs
+const (
+	ZlibCompression = uint16(iota + 1)
+	LZMACompression
+	LZOCompression
+	XZCompression
+	LZ4Compression
+	ZSTDCompression
+)
+
+func GetDecompressor(compType uint16) (Decompressor, error) {
+	switch compType {
+	case ZlibCompression:
+		return Zlib{}, nil
+	case LZMACompression:
+		return nil, errors.New("lzma compression is disable in this build with no_obsolete")
+	case LZOCompression:
+		return Lzo{}, nil
+	case XZCompression:
+		return Xz{}, nil
+	case LZ4Compression:
+		return Lz4{}, nil
+	case ZSTDCompression:
+		return &Zstd{}, nil
+	default:
+		return nil, errors.New("invalid compression type. possible corrupted archive")
+	}
+}

internal/decompress/get_decomp_no_obsolete.go

@@ -0,0 +1,34 @@
+//go:build no_gpl && no_obsolete
+
+package decompress
+
+import "errors"
+
+// The types of compression supported by squashfs
+const (
+	ZlibCompression = uint16(iota + 1)
+	LZMACompression
+	LZOCompression
+	XZCompression
+	LZ4Compression
+	ZSTDCompression
+)
+
+func GetDecompressor(compType uint16) (Decompressor, error) {
+	switch compType {
+	case ZlibCompression:
+		return Zlib{}, nil
+	case LZMACompression:
+		return nil, errors.New("lzma compression is disable in this build with no_obsolete")
+	case LZOCompression:
+		return nil, errors.New("lzo compression is disable in this build with no_gpl")
+	case XZCompression:
+		return Xz{}, nil
+	case LZ4Compression:
+		return Lz4{}, nil
+	case ZSTDCompression:
+		return &Zstd{}, nil
+	default:
+		return nil, errors.New("invalid compression type. possible corrupted archive")
+	}
+}

internal/decompress/lzma.go

@@ -1,4 +1,5 @@
 //go:build !no_lzma
+
 package decompress
 
 import (

internal/decompress/lzma_none.go

@@ -1,12 +0,0 @@
-//go:build no_lzma
-package decompress
-
-import (
-	"fmt"
-)
-
-type Lzma struct{}
-
-func (l Lzma) Decompress(_ []byte) ([]byte, error) {
-	return nil, fmt.Errorf("lzma is not supported")
-}

internal/decompress/lzo.go

@@ -1,4 +1,5 @@
 //go:build !no_lzo
+
 package decompress
 
 import (

internal/decompress/lzo_none.go

@@ -1,12 +0,0 @@
-//go:build no_lzo
-package decompress
-
-import (
-	"fmt"
-)
-
-type Lzo struct{}
-
-func (l Lzo) Decompress(_ []byte) ([]byte, error) {
-	return nil, fmt.Errorf("lzo is not supported")
-}

low/reader.go

@@ -55,21 +55,9 @@ func NewReader(r io.ReaderAt) (rdr *Reader, err error) {
 	if !rdr.Superblock.ValidVersion() {
 		return nil, ErrorVersion
 	}
-	switch rdr.Superblock.CompType {
-	case ZlibCompression:
-		rdr.d = decompress.Zlib{}
-	case LZMACompression:
-		rdr.d = decompress.Lzma{}
-	case LZOCompression:
-		rdr.d = decompress.Lzo{}
-	case XZCompression:
-		rdr.d = decompress.Xz{}
-	case LZ4Compression:
-		rdr.d = decompress.Lz4{}
-	case ZSTDCompression:
-		rdr.d = &decompress.Zstd{}
-	default:
-		return nil, errors.New("invalid compression type. possible corrupted archive")
+	rdr.d, err = decompress.GetDecompressor(rdr.Superblock.CompType)
+	if err != nil {
+		return nil, err
 	}
 	rdr.Root, err = rdr.directoryFromRef(rdr.Superblock.RootInodeRef, "")
 	if err != nil {