Mojo C++ bindings: inline pointer encoding/decoding/validating functions.

mojo/public/cpp/bindings/lib/validation_util.h

 // Copyright 2015 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_UTIL_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_UTIL_H_
 
 #include <stdint.h>
 
 #include "mojo/public/cpp/bindings/lib/bindings_internal.h"
 #include "mojo/public/cpp/bindings/lib/serialization_util.h"
 #include "mojo/public/cpp/bindings/lib/validate_params.h"
 #include "mojo/public/cpp/bindings/lib/validation_context.h"
 #include "mojo/public/cpp/bindings/lib/validation_errors.h"
 #include "mojo/public/cpp/bindings/message.h"
 
 namespace mojo {
 namespace internal {
 
 // Checks whether decoding the pointer will overflow and produce a pointer
 // smaller than |offset|.
-bool ValidateEncodedPointer(const uint64_t* offset);
+inline bool ValidateEncodedPointer(const uint64_t* offset) {
+  // - Make sure |*offset| is no more than 32-bits.
+  // - Cast |offset| to uintptr_t so overflow behavior is well defined across
+  //   32-bit and 64-bit systems.
+  return *offset <= std::numeric_limits<uint32_t>::max() &&
+         (reinterpret_cast<uintptr_t>(offset) +
+              static_cast<uint32_t>(*offset) >=
+          reinterpret_cast<uintptr_t>(offset));
+}
 
 template <typename T>
 bool ValidatePointer(const Pointer<T>& input,
                      ValidationContext* validation_context) {
   bool result = ValidateEncodedPointer(&input.offset);
   if (!result)
     ReportValidationError(validation_context, VALIDATION_ERROR_ILLEGAL_POINTER);
 
   return result;
 }
@@ skipping 128 matching lines @@
                                ValidationContext* validation_context);
 bool ValidateHandleOrInterface(const Interface_Data& input,
                                ValidationContext* validation_context);
 bool ValidateHandleOrInterface(const Handle_Data& input,
                                ValidationContext* validation_context);
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_UTIL_H_