Lock the prototype of internal classes.

test/mjsunit/builtins.js

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-natives-as=builtins
+
+// Checks that all function properties of the builtin object are neither
+// writable nor configurable. Also, theose functions that are actually
+// constructors (recognized by having properties on their .prototype object),
+// have only unconfigurable properties on the prototype, and the methods
+// are also non-writable.
+
+var names = Object.getOwnPropertyNames(builtins);
+
+function isFunction(obj) {
+  return typeof obj == "function";
+}
+
+function checkConstructor(func, name) {
+  // A constructor is a function with a prototype and properties on the
+  // prototype object besides "constructor";
+  if (name.charAt(0) == "$") return;
+  if (typeof func.prototype != "object") return;
+  var propNames = Object.getOwnPropertyNames(func.prototype);
+  if (propNames.length == 0 ||
+      (propNames.length == 1 && propNames[0] == "constructor")) {
+    // Not a constructor.
+    return;
+  }
+  var proto_desc = Object.getOwnPropertyDescriptor(func, "prototype");
+  assertTrue(proto_desc.hasOwnProperty("value"), name);
+  assertFalse(proto_desc.writable, name);
+  assertFalse(proto_desc.configurable, name);
+  var prototype = proto_desc.value;
+  assertEquals(null, prototype.__proto__, name);
+  assertFalse(Object.isExtensible(prototype), name);
+  for (var i = 0; i < propNames.length; i++) {
+    var propName = propNames[i];
+    if (propName == "constructor") continue;
+    var testName = name + "-" + propName;
+    var propDesc = Object.getOwnPropertyDescriptor(prototype, propName);
+    assertTrue(propDesc.hasOwnProperty("value"), testName);
+    assertFalse(propDesc.configurable, testName);
+    if (isFunction(propDesc.value)) {
+      assertFalse(propDesc.writable, testName);
+    }
+  }
+}
+
+for (var i = 0; i < names.length; i++) {
+  var name = names[i];
+  var desc = Object.getOwnPropertyDescriptor(builtins, name);
+  assertTrue(desc.hasOwnProperty("value"));
+  var value = desc.value;
+  if (isFunction(value)) {
+    assertFalse(desc.writable, name);
+    assertFalse(desc.configurable, name);
+    checkConstructor(value, name);
+  }
+}