Refactor LX symlink logic into dedicated functions

Extract LX symlink encode/decode into separate functions for better
maintainability and cleaner separation of concerns.

Signed-off-by: Varun Gokulnath <vagokuln@microsoft.com>
Signed-off-by: Varun Gokulnath <gvarun22@outlook.com>

reparse.go

@@ -53,12 +53,33 @@ func DecodeReparsePoint(b []byte) (*ReparsePoint, error) {
 }
 
 func DecodeReparsePointData(tag uint32, b []byte) (*ReparsePoint, error) {
-	isMountPoint := false
 	switch tag {
 	case reparseTagMountPoint:
-		isMountPoint = true
+		return decodeWindowsReparsePointData(b, true)
 	case reparseTagSymlink:
+		return decodeWindowsReparsePointData(b, false)
 	case reparseTagLxSymlink:
+		return decodeLxReparsePointData(b)
+	default:
+		return nil, &UnsupportedReparsePointError{tag}
+	}
+}
+
+func decodeWindowsReparsePointData(b []byte, isMountPoint bool) (*ReparsePoint, error) {
+	nameOffset := 8 + binary.LittleEndian.Uint16(b[4:6])
+	if !isMountPoint {
+		nameOffset += 4
+	}
+	nameLength := binary.LittleEndian.Uint16(b[6:8])
+	name := make([]uint16, nameLength/2)
+	err := binary.Read(bytes.NewReader(b[nameOffset:nameOffset+nameLength]), binary.LittleEndian, &name)
+	if err != nil {
+		return nil, err
+	}
+	return &ReparsePoint{Target: string(utf16.Decode(name)), IsMountPoint: isMountPoint, IsLxSymlink: false}, nil
+}
+
+func decodeLxReparsePointData(b []byte) (*ReparsePoint, error) {
 	// LX symlinks store the target as UTF-8 after a 4-byte version field
 	if len(b) < 4 {
 		return nil, errors.New("LX symlink buffer too short")
@@ -72,20 +93,6 @@ func DecodeReparsePointData(tag uint32, b []byte) (*ReparsePoint, error) {
 	}
 	target := string(targetBytes)
 	return &ReparsePoint{Target: target, IsMountPoint: false, IsLxSymlink: true}, nil
-	default:
-		return nil, &UnsupportedReparsePointError{tag}
-	}
-	nameOffset := 8 + binary.LittleEndian.Uint16(b[4:6])
-	if !isMountPoint {
-		nameOffset += 4
-	}
-	nameLength := binary.LittleEndian.Uint16(b[6:8])
-	name := make([]uint16, nameLength/2)
-	err := binary.Read(bytes.NewReader(b[nameOffset:nameOffset+nameLength]), binary.LittleEndian, &name)
-	if err != nil {
-		return nil, err
-	}
-	return &ReparsePoint{string(utf16.Decode(name)), isMountPoint, false}, nil
 }
 
 func isDriveLetter(c byte) bool {
@@ -96,6 +103,12 @@ func isDriveLetter(c byte) bool {
 // mount point, or LX symlink.
 func EncodeReparsePoint(rp *ReparsePoint) []byte {
 	if rp.IsLxSymlink {
+		return encodeLxReparsePoint(rp)
+	}
+	return encodeWindowsReparsePoint(rp)
+}
+
+func encodeLxReparsePoint(rp *ReparsePoint) []byte {
 	// LX symlink: 4-byte version + UTF-8 target
 	version := uint32(2)
 	targetBytes := []byte(rp.Target)
@@ -108,7 +121,9 @@ func EncodeReparsePoint(rp *ReparsePoint) []byte {
 	_ = binary.Write(&b, binary.LittleEndian, version)
 	_, _ = b.Write(targetBytes)
 	return b.Bytes()
-	}
+}
+
+func encodeWindowsReparsePoint(rp *ReparsePoint) []byte {
 
 	// Generate an NT path and determine if this is a relative path.
 	var ntTarget string