Merge pull request #1808 from dolthub/bh/escape-json-special-chars

escape special characters in strings

Author: bheni

sql/types/json_encode.go

@@ -8,6 +8,27 @@ import (
 	"strconv"
 )
 
+var isEscaped = [256]bool{}
+var escapeSeq = [256][]byte{}
+
+func init() {
+	isEscaped[uint8('\b')] = true
+	isEscaped[uint8('\f')] = true
+	isEscaped[uint8('\n')] = true
+	isEscaped[uint8('\r')] = true
+	isEscaped[uint8('\t')] = true
+	isEscaped[uint8('"')] = true
+	isEscaped[uint8('\\')] = true
+
+	escapeSeq[uint8('\b')] = []byte("\\b")
+	escapeSeq[uint8('\f')] = []byte("\\f")
+	escapeSeq[uint8('\n')] = []byte("\\n")
+	escapeSeq[uint8('\r')] = []byte("\\r")
+	escapeSeq[uint8('\t')] = []byte("\\t")
+	escapeSeq[uint8('"')] = []byte("\\\"")
+	escapeSeq[uint8('\\')] = []byte("\\\\")
+}
+
 type NoCopyBuilder struct {
 	buffers   [][]byte
 	curr      int
@@ -191,7 +212,28 @@ func writeMarshalledValue(writer io.Writer, val interface{}) error {
 
 	case string:
 		writer.Write([]byte{'"'})
-		writer.Write([]byte(val))
+		// iterate over each rune in the string to escape any special characters
+		start := 0
+		for i, r := range val {
+			if r > '\\' {
+				continue
+			}
+
+			b := uint8(r)
+			if isEscaped[b] {
+				if start != i {
+					writer.Write([]byte(val[start:i]))
+				}
+
+				writer.Write(escapeSeq[b])
+				start = i + 1
+			}
+		}
+
+		if start != len(val) {
+			writer.Write([]byte(val[start:]))
+		}
+
 		writer.Write([]byte{'"'})
 		return nil
 

sql/types/json_encode_test.go

@@ -64,6 +64,30 @@ func TestMarshalToMySqlString(t *testing.T) {
 			},
 			expected: `{"baz": "qux", "foo": "bar"}`,
 		},
+		{
+			name: "string formatting",
+			val: []string{
+				`simple`,
+				`With "quotes"`,
+				`With "quotes" not at the end`,
+				`with 'single quotes'`,
+				`with
+newlines
+`,
+				`with \n escaped newline`,
+				`with	`,
+			},
+			expected: `["simple", "With \"quotes\"", "With \"quotes\" not at the end", "with 'single quotes'", "with\nnewlines\n", "with \\n escaped newline", "with\t"]`,
+		},
+		{
+			name: "complicated string",
+			val: []string{
+				`{
+	"nested": "json",
+	"nested_escapedQuotes": "here \"you\" go"
+}`},
+			expected: `["{\n\t\"nested\": \"json\",\n\t\"nested_escapedQuotes\": \"here \\\"you\\\" go\"\n}"]`,
+		},
 	}
 
 	for _, test := range tests {