fix bug on hex escape table

number of items on `hexvals` is 128 while table size is 256, so
remaining 128 items are filled with zero. As a result, values in
\xf0-\xff will be treated as zero while should be rejected.

c_src/utf8.c

@@ -19,6 +19,23 @@ static const unsigned char hexvals[256] = {
     255,  10,  11,  12,  13,  14,  15, 255,
     255, 255, 255, 255, 255, 255, 255, 255,
     255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
+    255, 255, 255, 255, 255, 255, 255, 255,
     255, 255, 255, 255, 255, 255, 255, 255
 };
 

test/jiffy_04_string_tests.erl

@@ -118,6 +118,7 @@ cases(error) ->
         <<"\"", 0, "\"">>,
         <<"\"\\g\"">>,
         <<"\"\\uD834foo\\uDD1E\"">>,
+        <<"\"\\u", 200, 200, 200, 200, "\"">>,
         % CouchDB-345
         <<34,78,69,73,77,69,78,32,70,216,82,82,32,70,65,69,78,33,34>>
     ];