Initial in-process implementation of some Mojo primitives.

mojo/system/memory.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/system/memory.h"
+
+#include <limits>
+
+#include "base/logging.h"
+
+namespace mojo {
+namespace system {
+
+bool VerifyUserPointer(const void* pointer, size_t count, size_t size_each) {
+  DCHECK_GT(size_each, 0u);
+  if (count > std::numeric_limits<size_t>::max() / size_each)
+    return false;
+
+  // TODO(vtl): If running in kernel mode, do a full verification. For now, just
+  // check that it's non-null if |size| is nonzero. (A faster user mode
+  // implementation is also possible if this check is skipped.)
+  return count == 0 || !!pointer;
+}
+
+}  // namespace system
+}  // namespace mojo