JsonPrinter remove trailing garbage after non-printable char (#950)

Author: ywhrh

sbe-tool/src/main/java/uk/co/real_logic/sbe/json/JsonTokenListener.java

@@ -336,12 +336,7 @@ private void appendEncodingAsString(
             if (size > 1 && encoding.primitiveType() == CHAR)
             {
                 doubleQuote();
-
-                for (int i = 0; i < size; i++)
-                {
-                    escape((char)buffer.getByte(index + (i * elementSize)));
-                }
-
+                escapePrintableChar(buffer, index, size, elementSize);
                 doubleQuote();
             }
             else
@@ -369,6 +364,22 @@ private void appendEncodingAsString(
         }
     }
 
+    private void escapePrintableChar(final DirectBuffer buffer, final int index, final int size, final int elementSize)
+    {
+        for (int i = 0; i < size; i++)
+        {
+            final byte c = buffer.getByte(index + (i * elementSize));
+            if (c > 0)
+            {
+                escape((char)c);
+            }
+            else
+            {
+                break;
+            }
+        }
+    }
+
     private void backup()
     {
         final int newLength = output.length() - 2;

sbe-tool/src/test/java/uk/co/real_logic/sbe/json/JsonPrinterTest.java

@@ -15,6 +15,7 @@
  */
 package uk.co.real_logic.sbe.json;
 
+import baseline.CarEncoder;
 import baseline.CredentialsEncoder;
 import baseline.MessageHeaderEncoder;
 import org.agrona.concurrent.UnsafeBuffer;
@@ -155,6 +156,37 @@ public void exampleVarData() throws Exception
             result);
     }
 
+    @Test
+    public void removeTrailingGarbage() throws Exception
+    {
+        final ByteBuffer encodedSchemaBuffer = ByteBuffer.allocate(SCHEMA_BUFFER_CAPACITY);
+        encodeSchema(encodedSchemaBuffer);
+
+        final ByteBuffer encodedMsgBuffer = ByteBuffer.allocate(MSG_BUFFER_CAPACITY);
+        final UnsafeBuffer buffer = new UnsafeBuffer(encodedMsgBuffer);
+        final CarEncoder encoder = new CarEncoder();
+        encoder.wrapAndApplyHeader(buffer, 0, new MessageHeaderEncoder());
+        encoder.vehicleCode("vc\0ﾉ�");
+        encodedMsgBuffer.position(encoder.encodedLength());
+        encodedSchemaBuffer.flip();
+        final Ir ir = decodeIr(encodedSchemaBuffer);
+
+        final JsonPrinter printer = new JsonPrinter(ir);
+        final String result = printer.print(encodedMsgBuffer);
+        assertEquals("{\n" + "    \"serialNumber\": 0,\n" +
+            "    \"modelYear\": 0,\n" +
+            "    \"available\": \"F\",\n" + "    \"code\": \"null\",\n" + "    \"someNumbers\": [0, 0, 0, 0, 0],\n" +
+            "    \"vehicleCode\": \"vc\",\n" + //trailing garbage removed
+            "    \"extras\": { \"sunRoof\": false, \"sportsPack\": false, \"cruiseControl\": false },\n" +
+            "    \"engine\": \n" + "    {\n" + "        \"capacity\": 0,\n" + "        \"numCylinders\": 0,\n" +
+            "        \"maxRpm\": 9000,\n" + "        \"manufacturerCode\": \"\",\n" +
+            "        \"fuel\": \"Petrol\"\n" + "    },\n" + "    \"uuid\": [0, 0],\n" + "    \"cupHolderCount\": 0,\n" +
+            "    \"fuelFigures\": [],\n" + "    \"performanceFigures\": [],\n" + "    \"manufacturer\": \"\",\n" +
+            "    \"model\": \"\",\n" + "    \"activationCode\": \"\"\n" + "}",
+            result);
+    }
+
+
     private static void encodeSchema(final ByteBuffer buffer) throws Exception
     {
         final Path path = Paths.get("src/test/resources/json-printer-test-schema.xml");