1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "base/rand_util.h"
11 // #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036. See the
12 // "Community Additions" comment on MSDN here:
13 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx
14 #define SystemFunction036 NTAPI SystemFunction036
16 #undef SystemFunction036
21 #include "base/check.h"
25 void RandBytes(void* output, size_t output_length) {
26 char* output_ptr = static_cast<char*>(output);
27 while (output_length > 0) {
28 const ULONG output_bytes_this_pass = static_cast<ULONG>(std::min(
29 output_length, static_cast<size_t>(std::numeric_limits<ULONG>::max())));
31 RtlGenRandom(output_ptr, output_bytes_this_pass) != FALSE;
33 output_length -= output_bytes_this_pass;
34 output_ptr += output_bytes_this_pass;