Use uint32 to decode directory entry length

Use unsigned integers for the ExtentLength field of directory entries.

Author: aarzilli

image_writer.go

@@ -165,7 +165,6 @@ func manglePath(input string) (string, string) {
 // @param {string} givenPath Path to convert
 //
 // @returns {string} Converted filepath
-//
 func posixifyPath(path string) string {
 	if runtime.GOOS == "windows" {
 		return strings.ReplaceAll(path, "\\", "/")
@@ -297,7 +296,7 @@ func (wc *writeContext) createDEForRoot() (*DirectoryEntry, error) {
 	de := &DirectoryEntry{
 		ExtendedAtributeRecordLength: 0,
 		ExtentLocation:               int32(extentLocation),
-		ExtentLength:                 int32(extentLengthInSectors * sectorSize),
+		ExtentLength:                 uint32(extentLengthInSectors * sectorSize),
 		RecordingDateTime:            wc.timestamp,
 		FileFlags:                    dirFlagDir,
 		FileUnitSize:                 0, // 0 for non-interleaved write
@@ -355,7 +354,7 @@ func (wc *writeContext) scanDirectory(item *itemToWrite, dirPath string, ownEntr
 		de := &DirectoryEntry{
 			ExtendedAtributeRecordLength: 0,
 			ExtentLocation:               int32(extentLocation),
-			ExtentLength:                 int32(extentLength),
+			ExtentLength:                 uint32(extentLength),
 			RecordingDateTime:            wc.timestamp,
 			FileFlags:                    fileFlags,
 			FileUnitSize:                 0, // 0 for non-interleaved write

iso9660.go

@@ -127,7 +127,7 @@ var _ encoding.BinaryMarshaler = PrimaryVolumeDescriptorBody{}
 type DirectoryEntry struct {
 	ExtendedAtributeRecordLength byte
 	ExtentLocation               int32
-	ExtentLength                 int32
+	ExtentLength                 uint32
 	RecordingDateTime            RecordingTimestamp
 	FileFlags                    byte
 	FileUnitSize                 byte
@@ -155,7 +155,7 @@ func (de *DirectoryEntry) UnmarshalBinary(data []byte) error {
 		return err
 	}
 
-	if de.ExtentLength, err = UnmarshalInt32LSBMSB(data[10:18]); err != nil {
+	if de.ExtentLength, err = UnmarshalUint32LSBMSB(data[10:18]); err != nil {
 		return err
 	}
 
@@ -196,7 +196,7 @@ func (de *DirectoryEntry) MarshalBinary() ([]byte, error) {
 	data[1] = de.ExtendedAtributeRecordLength
 
 	WriteInt32LSBMSB(data[2:10], de.ExtentLocation)
-	WriteInt32LSBMSB(data[10:18], de.ExtentLength)
+	WriteInt32LSBMSB(data[10:18], int32(de.ExtentLength))
 	de.RecordingDateTime.MarshalBinary(data[18:25])
 	data[25] = de.FileFlags
 	data[26] = de.FileUnitSize

iso9660_datatypes.go

@@ -33,6 +33,12 @@ func UnmarshalInt32LSBMSB(data []byte) (int32, error) {
 	return lsb, nil
 }
 
+// UnmarshalUint32LSBMSB is the same as UnmarshalInt32LSBMSB but returns an unsigned integer
+func UnmarshalUint32LSBMSB(data []byte) (uint32, error) {
+	n, err := UnmarshalInt32LSBMSB(data)
+	return uint32(n), err
+}
+
 // UnmarshalInt16LSBMSB decodes a 16-bit integer in both byte orders, as defined in ECMA-119 7.3.3
 func UnmarshalInt16LSBMSB(data []byte) (int16, error) {
 	if len(data) < 4 {