fix for "iphone 5" type 5 issue (#52)

* fix for "iphone 5" type 5 issue

"type 5" error when running iphone 5, Added handling for "type 5"

* add testcase for "type 5"

Author: joonghyup-cha

screencapture/common/nsnumber.go

@@ -45,6 +45,12 @@ func NewNSNumber(bytes []byte) (NSNumber, error) {
 		}
 		value := math.Float64frombits(binary.LittleEndian.Uint64(bytes[1:]))
 		return NSNumber{typeSpecifier: typeSpecifier, FloatValue: value}, nil
+	case 5:
+		if len(bytes) != 5 {
+			return NSNumber{}, fmt.Errorf("the NSNumber, type 5 should contain 4 bytes: %s", hex.Dump(bytes))
+		}
+		value := binary.LittleEndian.Uint32(bytes[1:])
+		return NSNumber{typeSpecifier: typeSpecifier, IntValue: value}, nil
 	case 4:
 		if len(bytes) != 9 {
 			return NSNumber{}, fmt.Errorf("the NSNumber, type 4 should contain 8 bytes: %s", hex.Dump(bytes))

screencapture/common/nsnumber_test.go

@@ -8,12 +8,14 @@ import (
 
 //I took these from hexdumps
 var typeSix = []byte{0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x9E, 0x40}
+var typeFive = []byte{0x05, 0x2E, 00, 00, 00}
 var typeFour = []byte{0x04, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
 var typeThree = []byte{0x03, 0x1E, 00, 00, 00}
 
 const typeSixDecoded float64 = 1920
-const typeThreeDecoded uint32 = 30
+const typeFiveDecoded uint32 = 46
 const typeFourDecoded uint64 = 5
+const typeThreeDecoded uint32 = 30
 
 func TestErrors(t *testing.T) {
 	var broken []byte
@@ -36,6 +38,12 @@ func TestErrors(t *testing.T) {
 	broken[0] = 56
 	_, err = common.NewNSNumber(broken)
 	assert.Error(t, err)
+
+	broken = make([]byte, len(typeFive))
+	copy(broken, typeFive)
+	broken[0] = 134
+	_, err = common.NewNSNumber(broken)
+	assert.Error(t, err)
 }
 
 func TestNumberValue(t *testing.T) {
@@ -45,12 +53,17 @@ func TestNumberValue(t *testing.T) {
 		assert.Equal(t, typeSixDecoded, float64Num.FloatValue)
 	}
 
+	uint32Num, err := common.NewNSNumber(typeFive)
+	if assert.NoError(t, err) {
+		assert.Equal(t, typeFiveDecoded, uint32Num.IntValue)
+	}
+
 	uint64Num, err := common.NewNSNumber(typeFour)
 	if assert.NoError(t, err) {
 		assert.Equal(t, typeFourDecoded, uint64Num.LongValue)
 	}
 
-	uint32Num, err := common.NewNSNumber(typeThree)
+	uint32Num, err = common.NewNSNumber(typeThree)
 	if assert.NoError(t, err) {
 		assert.Equal(t, typeThreeDecoded, uint32Num.IntValue)
 	}