Handle non-printable control characters when escaping JSON

Author: mediremi

analysis/vendor/json/Json.ml

@@ -141,7 +141,10 @@ let escape text =
       | '\b' -> Buffer.add_string buf "\\b"
       | '\r' -> Buffer.add_string buf "\\r"
       | '\t' -> Buffer.add_string buf "\\t"
-      | c -> Buffer.add_char buf c);
+      | c ->
+        let code = Char.code c in
+        if code < 0x20 then Printf.bprintf buf "\\u%04x" code
+        else Buffer.add_char buf c);
       loop (i + 1))
   in
   loop 0;

tests/ounit_tests/dune

@@ -11,4 +11,4 @@
   (<> %{profile} browser))
  (flags
   (:standard -w +a-4-9-30-40-41-42-48-70))
- (libraries bsb bsb_helper core ounit2))
+ (libraries bsb bsb_helper core ounit2 analysis))

tests/ounit_tests/ounit_json_tests.ml

@@ -0,0 +1,14 @@
+let ( >:: ), ( >::: ) = OUnit.(( >:: ), ( >::: ))
+
+let suites =
+  __FILE__
+  >::: [
+         ( "escape 'hello'" >:: fun _ ->
+           let escaped = Json.escape "hello" in
+           let expected = "hello" in
+           OUnit.assert_equal escaped expected );
+         ( "escape \\x17" >:: fun _ ->
+           let escaped = Json.escape "\x17" in
+           let expected = "\\u0017" in
+           OUnit.assert_equal escaped expected );
+       ]

tests/ounit_tests/ounit_tests_main.ml

@@ -2,6 +2,7 @@ let suites =
   OUnit.( >::: ) __FILE__
     [
       Ounit_vec_test.suites;
+      Ounit_json_tests.suites;
       Ounit_ext_json_tests.suites;
       Ounit_path_tests.suites;
       Ounit_array_tests.suites;