Fix decoding of backslash char at the end of string

decode_context.go

@@ -55,10 +55,12 @@ func skipObject(buf []byte, cursor, depth int64) (int64, error) {
 			for {
 				cursor++
 				switch buf[cursor] {
-				case '"':
+				case '\\':
-					if buf[cursor-1] == '\\' {
+					cursor++
-						continue
+					if buf[cursor] == nul {
+						return 0, errUnexpectedEndOfJSON("string of object", cursor)
 					}
+				case '"':
 					goto SWITCH_OUT
 				case nul:
 					return 0, errUnexpectedEndOfJSON("string of object", cursor)
@@ -99,10 +101,12 @@ func skipArray(buf []byte, cursor, depth int64) (int64, error) {
 			for {
 				cursor++
 				switch buf[cursor] {
-				case '"':
+				case '\\':
-					if buf[cursor-1] == '\\' {
+					cursor++
-						continue
+					if buf[cursor] == nul {
+						return 0, errUnexpectedEndOfJSON("string of object", cursor)
 					}
+				case '"':
 					goto SWITCH_OUT
 				case nul:
 					return 0, errUnexpectedEndOfJSON("string of object", cursor)
@@ -130,10 +134,12 @@ func skipValue(buf []byte, cursor, depth int64) (int64, error) {
 			for {
 				cursor++
 				switch buf[cursor] {
-				case '"':
+				case '\\':
-					if buf[cursor-1] == '\\' {
+					cursor++
-						continue
+					if buf[cursor] == nul {
+						return 0, errUnexpectedEndOfJSON("string of object", cursor)
 					}
+				case '"':
 					return cursor + 1, nil
 				case nul:
 					return 0, errUnexpectedEndOfJSON("string of object", cursor)
@@ -184,18 +190,8 @@ func skipValue(buf []byte, cursor, depth int64) (int64, error) {
 			cursor += 5
 			return cursor, nil
 		case 'n':
-			buflen := int64(len(buf))
+			if err := validateNull(buf, cursor); err != nil {
-			if cursor+3 >= buflen {
+				return 0, err
-				return 0, errUnexpectedEndOfJSON("null", cursor)
-			}
-			if buf[cursor+1] != 'u' {
-				return 0, errUnexpectedEndOfJSON("null", cursor)
-			}
-			if buf[cursor+2] != 'l' {
-				return 0, errUnexpectedEndOfJSON("null", cursor)
-			}
-			if buf[cursor+3] != 'l' {
-				return 0, errUnexpectedEndOfJSON("null", cursor)
 			}
 			cursor += 4
 			return cursor, nil

decode_stream.go

@@ -126,10 +126,18 @@ func (s *stream) skipObject(depth int64) error {
 			for {
 				cursor++
 				switch char(p, cursor) {
-				case '"':
+				case '\\':
-					if char(p, cursor-1) == '\\' {
+					cursor++
+					if char(p, cursor) == nul {
+						s.cursor = cursor
+						if s.read() {
+							s.cursor-- // for retry current character
+							_, cursor, p = s.stat()
 							continue
 						}
+						return errUnexpectedEndOfJSON("string of object", cursor)
+					}
+				case '"':
 					goto SWITCH_OUT
 				case nul:
 					s.cursor = cursor
@@ -183,10 +191,18 @@ func (s *stream) skipArray(depth int64) error {
 			for {
 				cursor++
 				switch char(p, cursor) {
-				case '"':
+				case '\\':
-					if char(p, cursor-1) == '\\' {
+					cursor++
+					if char(p, cursor) == nul {
+						s.cursor = cursor
+						if s.read() {
+							s.cursor-- // for retry current character
+							_, cursor, p = s.stat()
 							continue
 						}
+						return errUnexpectedEndOfJSON("string of object", cursor)
+					}
+				case '"':
 					goto SWITCH_OUT
 				case nul:
 					s.cursor = cursor
@@ -235,10 +251,18 @@ func (s *stream) skipValue(depth int64) error {
 			for {
 				cursor++
 				switch char(p, cursor) {
-				case '"':
+				case '\\':
-					if char(p, cursor-1) == '\\' {
+					cursor++
+					if char(p, cursor) == nul {
+						s.cursor = cursor
+						if s.read() {
+							s.cursor-- // for retry current character
+							_, cursor, p = s.stat()
 							continue
 						}
+						return errUnexpectedEndOfJSON("value of string", s.totalOffset())
+					}
+				case '"':
 					s.cursor = cursor + 1
 					return nil
 				case nul:

decode_test.go

@@ -3417,3 +3417,88 @@ func TestDecodeByteSliceNull(t *testing.T) {
 		}
 	})
 }
+
+func TestDecodeBackSlash(t *testing.T) {
+	t.Run("unmarshal", func(t *testing.T) {
+		t.Run("string", func(t *testing.T) {
+			var v1 map[string]stdjson.RawMessage
+			if err := stdjson.Unmarshal([]byte(`{"c":"\\"}`), &v1); err != nil {
+				t.Fatal(err)
+			}
+			var v2 map[string]json.RawMessage
+			if err := json.Unmarshal([]byte(`{"c":"\\"}`), &v2); err != nil {
+				t.Fatal(err)
+			}
+			if len(v1) != len(v2) || !bytes.Equal(v1["c"], v2["c"]) {
+				t.Fatalf("failed to decode backslash: expected %#v but got %#v", v1, v2)
+			}
+		})
+		t.Run("array", func(t *testing.T) {
+			var v1 map[string]stdjson.RawMessage
+			if err := stdjson.Unmarshal([]byte(`{"c":["\\"]}`), &v1); err != nil {
+				t.Fatal(err)
+			}
+			var v2 map[string]json.RawMessage
+			if err := json.Unmarshal([]byte(`{"c":["\\"]}`), &v2); err != nil {
+				t.Fatal(err)
+			}
+			if len(v1) != len(v2) || !bytes.Equal(v1["c"], v2["c"]) {
+				t.Fatalf("failed to decode backslash: expected %#v but got %#v", v1, v2)
+			}
+		})
+		t.Run("object", func(t *testing.T) {
+			var v1 map[string]stdjson.RawMessage
+			if err := stdjson.Unmarshal([]byte(`{"c":{"\\":"\\"}}`), &v1); err != nil {
+				t.Fatal(err)
+			}
+			var v2 map[string]json.RawMessage
+			if err := json.Unmarshal([]byte(`{"c":{"\\":"\\"}}`), &v2); err != nil {
+				t.Fatal(err)
+			}
+			if len(v1) != len(v2) || !bytes.Equal(v1["c"], v2["c"]) {
+				t.Fatalf("failed to decode backslash: expected %#v but got %#v", v1, v2)
+			}
+		})
+	})
+	t.Run("stream", func(t *testing.T) {
+		t.Run("string", func(t *testing.T) {
+			var v1 map[string]stdjson.RawMessage
+			if err := stdjson.NewDecoder(strings.NewReader(`{"c":"\\"}`)).Decode(&v1); err != nil {
+				t.Fatal(err)
+			}
+			var v2 map[string]json.RawMessage
+			if err := json.NewDecoder(strings.NewReader(`{"c":"\\"}`)).Decode(&v2); err != nil {
+				t.Fatal(err)
+			}
+			if len(v1) != len(v2) || !bytes.Equal(v1["c"], v2["c"]) {
+				t.Fatalf("failed to decode backslash: expected %#v but got %#v", v1, v2)
+			}
+		})
+		t.Run("array", func(t *testing.T) {
+			var v1 map[string]stdjson.RawMessage
+			if err := stdjson.NewDecoder(strings.NewReader(`{"c":["\\"]}`)).Decode(&v1); err != nil {
+				t.Fatal(err)
+			}
+			var v2 map[string]json.RawMessage
+			if err := json.NewDecoder(strings.NewReader(`{"c":["\\"]}`)).Decode(&v2); err != nil {
+				t.Fatal(err)
+			}
+			if len(v1) != len(v2) || !bytes.Equal(v1["c"], v2["c"]) {
+				t.Fatalf("failed to decode backslash: expected %#v but got %#v", v1, v2)
+			}
+		})
+		t.Run("object", func(t *testing.T) {
+			var v1 map[string]stdjson.RawMessage
+			if err := stdjson.NewDecoder(strings.NewReader(`{"c":{"\\":"\\"}}`)).Decode(&v1); err != nil {
+				t.Fatal(err)
+			}
+			var v2 map[string]json.RawMessage
+			if err := json.NewDecoder(strings.NewReader(`{"c":{"\\":"\\"}}`)).Decode(&v2); err != nil {
+				t.Fatal(err)
+			}
+			if len(v1) != len(v2) || !bytes.Equal(v1["c"], v2["c"]) {
+				t.Fatalf("failed to decode backslash: expected %#v but got %#v", v1, v2)
+			}
+		})
+	})
+}