Check input end when parsing JSON

Before this change, the end of input after reading a JSON value
was not properly validated:
- if there were remaining characters which did not parse as JSON,
  exception was thrown. E.g. `'["correct JSON"]and more'` failed
- if there were remaining characters which formed a valid token,
  they were silently ignored. E.g. `'["correct JSON"]{and more'`
  succeeded and returned `'["correct JSON"]'`

After this change, any trailing characters are caught and reported
as error.

core/trino-main/src/test/java/io/trino/operator/scalar/TestJsonFunctions.java

@@ -278,6 +278,11 @@ public void testInvalidJsonParse()
         assertInvalidFunction("JSON 'INVALID'", INVALID_FUNCTION_ARGUMENT);
         assertInvalidFunction("JSON_PARSE('INVALID')", INVALID_FUNCTION_ARGUMENT);
         assertInvalidFunction("JSON_PARSE('\"x\": 1')", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON_PARSE('{}{')", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON_PARSE('{} \"a\"')", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON_PARSE('{}{abc')", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON_PARSE('{}abc')", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON_PARSE('')", INVALID_FUNCTION_ARGUMENT);
     }
 
     @Test

core/trino-main/src/test/java/io/trino/sql/analyzer/TestAnalyzer.java

@@ -3254,6 +3254,17 @@ public void testLiteral()
                 .hasErrorCode(INVALID_LITERAL);
     }
 
+    @Test
+    public void testJsonLiteral()
+    {
+        // TODO All the below should fail. Literals should be validated during analysis https://github.com/trinodb/trino/issues/10719
+        analyze("SELECT JSON '{}{'");
+        analyze("SELECT JSON '{} \"a\"'");
+        analyze("SELECT JSON '{}{abc'");
+        analyze("SELECT JSON '{}abc'");
+        analyze("SELECT JSON ''");
+    }
+
     @Test
     public void testLambda()
     {

core/trino-main/src/test/java/io/trino/type/TestJsonOperators.java

@@ -180,6 +180,11 @@ public void testTypeConstructor()
         assertFunction("JSON '[null]'", JSON, "[null]");
         assertFunction("JSON '[13,null,42]'", JSON, "[13,null,42]");
         assertFunction("JSON '{\"x\": null}'", JSON, "{\"x\":null}");
+        assertInvalidFunction("JSON '{}{'", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON '{} \"a\"'", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON '{}{abc'", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON '{}abc'", INVALID_FUNCTION_ARGUMENT);
+        assertInvalidFunction("JSON ''", INVALID_FUNCTION_ARGUMENT);
     }
 
     @Test

lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/util/JsonTypeUtil.java

@@ -30,6 +30,7 @@
 
 import static com.fasterxml.jackson.core.JsonFactory.Feature.CANONICALIZE_FIELD_NAMES;
 import static com.fasterxml.jackson.databind.SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS;
+import static com.google.common.base.Preconditions.checkState;
 import static io.trino.spi.StandardErrorCode.INVALID_FUNCTION_ARGUMENT;
 import static java.lang.String.format;
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -50,9 +51,11 @@ public static Slice jsonParse(Slice slice)
         try (JsonParser parser = createJsonParser(JSON_FACTORY, slice)) {
             SliceOutput output = new DynamicSliceOutput(slice.length());
             SORTED_MAPPER.writeValue((OutputStream) output, SORTED_MAPPER.readValue(parser, Object.class));
-            // nextToken() returns null if the input is parsed correctly,
-            // but will throw an exception if there are trailing characters.
-            parser.nextToken();
+            // At this point, the end of input should be reached. nextToken() has three possible results:
+            // - null, if the end of the input was reached
+            // - token, if a correct JSON token is found (e.g. '{', 'null', '1')
+            // - exception, if there are characters which do not form a valid JSON token (e.g. 'abc')
+            checkState(parser.nextToken() == null, "Found characters after the expected end of input");
             return output.slice();
         }
         catch (IOException | RuntimeException e) {