fix bug on escape sequence when skiping object or array

Author: francois.parquet

decode_array.go

@@ -79,26 +79,34 @@ func (dec *Decoder) skipArray() (int, error) {
 			arraysOpen++
 		case '"':
 			j++
-			for ; j < dec.length; j++ {
+			var isInEscapeSeq bool
+			var isFirstQuote = true
+			for ; j < dec.length || dec.read(); j++ {
 				if dec.data[j] != '"' {
 					continue
 				}
-				if dec.data[j-1] != '\\' {
+				if dec.data[j-1] != '\\' || (!isInEscapeSeq && !isFirstQuote) {
 					break
+				} else {
+					isInEscapeSeq = false
+				}
+				if isFirstQuote {
+					isFirstQuote = false
 				}
 				// loop backward and count how many anti slash found
 				// to see if string is effectively escaped
-				ct := 1
-				for i := j - 2; i > 0; i-- {
+				ct := 0
+				for i := j - 1; i > 0; i-- {
 					if dec.data[i] != '\\' {
 						break
 					}
 					ct++
 				}
-				// is even number of slashes, quote is not escaped
+				// is pair number of slashes, quote is not escaped
 				if ct&1 == 0 {
 					break
 				}
+				isInEscapeSeq = true
 			}
 		default:
 			continue

decode_array_test.go

@@ -510,24 +510,28 @@ func TestUnmarshalJSONArrays(t *testing.T) {
 
 func TestSkipArray(t *testing.T) {
 	testCases := []struct {
+		name         string
 		json         string
 		expectations func(*testing.T, int, error)
 	}{
 		{
+			name: "basic",
 			json: `"testbasic"]`,
 			expectations: func(t *testing.T, i int, err error) {
 				assert.Equal(t, len(`"testbasic"]`), i)
 				assert.Nil(t, err)
 			},
 		},
 		{
+			name: "complex escape string",
 			json: `"test \\\\\" escape"]`,
 			expectations: func(t *testing.T, i int, err error) {
 				assert.Equal(t, len(`"test \\\\\" escape"]`), i)
 				assert.Nil(t, err)
 			},
 		},
 		{
+			name: "complex escape slash",
 			json: `"test \\\\\\"]`,
 			expectations: func(t *testing.T, i int, err error) {
 				assert.Equal(t, len(`"test \\\\\\"]`), i)
@@ -537,9 +541,11 @@ func TestSkipArray(t *testing.T) {
 	}
 
 	for _, test := range testCases {
-		dec := NewDecoder(strings.NewReader(test.json))
-		i, err := dec.skipArray()
-		test.expectations(t, i, err)
+		t.Run(test.name, func(t *testing.T) {
+			dec := NewDecoder(strings.NewReader(test.json))
+			i, err := dec.skipArray()
+			test.expectations(t, i, err)
+		})
 	}
 }
 

decode_object.go

@@ -116,16 +116,23 @@ func (dec *Decoder) skipObject() (int, error) {
 			objectsOpen++
 		case '"':
 			j++
+			var isInEscapeSeq bool
+			var isFirstQuote = true
 			for ; j < dec.length || dec.read(); j++ {
 				if dec.data[j] != '"' {
 					continue
 				}
-				if dec.data[j-1] != '\\' {
+				if dec.data[j-1] != '\\' || (!isInEscapeSeq && !isFirstQuote) {
 					break
+				} else {
+					isInEscapeSeq = false
+				}
+				if isFirstQuote {
+					isFirstQuote = false
 				}
 				// loop backward and count how many anti slash found
 				// to see if string is effectively escaped
-				ct := 1
+				ct := 0
 				for i := j - 1; i > 0; i-- {
 					if dec.data[i] != '\\' {
 						break
@@ -134,8 +141,9 @@ func (dec *Decoder) skipObject() (int, error) {
 				}
 				// is pair number of slashes, quote is not escaped
 				if ct&1 == 0 {
-					continue
+					break
 				}
+				isInEscapeSeq = true
 			}
 		default:
 			continue

decode_object_test.go

@@ -1370,7 +1370,7 @@ func TestSkipObject(t *testing.T) {
 		},
 		{
 			name: "basic-escaped",
-			json: `"key":"value\\\\\\" hello"}`,
+			json: `"key":"value\\\\\\\" hello"}`,
 		},
 		{
 			name: "basic-err",