rand_util_win.cc - mozsearch

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// Copyright (c) 2012 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 "base/rand_util.h"

#include <windows.h>

#include <stddef.h>

#include <stdint.h>

// #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036.  See the

// "Community Additions" comment on MSDN here:

// http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx

#define SystemFunction036 NTAPI SystemFunction036

#include <ntsecapi.h>

#undef SystemFunction036

#include <algorithm>

#include <limits>

#include "base/logging.h"

namespace base {

void RandBytes(void* output, size_t output_length) {

  char* output_ptr = static_cast<char*>(output);

  while (output_length > 0) {

    const ULONG output_bytes_this_pass = static_cast<ULONG>(std::min(

        output_length, static_cast<size_t>(std::numeric_limits<ULONG>::max())));

    const bool success =

        RtlGenRandom(output_ptr, output_bytes_this_pass) != FALSE;

    CHECK(success);

    output_length -= output_bytes_this_pass;

    output_ptr += output_bytes_this_pass;

}  // namespace base