Mojo: More data pipe implementation.

mojo/system/memory.h

 // 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.
 
 #ifndef MOJO_SYSTEM_MEMORY_H_
 #define MOJO_SYSTEM_MEMORY_H_
 
 #include <stddef.h>
 
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
 namespace system {
 
 // This is just forward-declared, with the definition and explicit
 // instantiations in the .cc file. This is used by |VerifyUserPointer<T>()|
 // below, and you should use that instead.
 template <size_t size>
 bool MOJO_SYSTEM_IMPL_EXPORT VerifyUserPointerForSize(const void* pointer,
                                                       size_t count);
 
+// A non-templatized version of the above, for when the element size isn't
+// fixed.
+bool MOJO_SYSTEM_IMPL_EXPORT VerifyUserPointerForSize(const void* pointer,
+                                                      size_t size,
+                                                      size_t count);
+
 // Verify that |count * sizeof(T)| bytes can be read from the user |pointer|
 // insofar as possible/necessary (note: this is done carefully since |count *
 // sizeof(T)| may overflow a |size_t|. |count| may be zero. If |T| is |void|,
 // then the size of each element is taken to be a single byte.
 //
 // For example, if running in kernel mode, this should be a full verification
 // that the given memory is owned and readable by the user process. In user
 // mode, if crashes are acceptable, this may do nothing at all (and always
 // return true).
 template <typename T>
 bool VerifyUserPointer(const T* pointer, size_t count) {
   return VerifyUserPointerForSize<sizeof(T)>(pointer, count);
 }
 
 // Special-case |T| equals |void| so that the size is in bytes, as indicated
 // above.
 template <>
 inline bool VerifyUserPointer<void>(const void* pointer, size_t count) {
   return VerifyUserPointerForSize<1>(pointer, count);
 }
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MEMORY_H_