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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "chrome/common/rand_util.h"
#include <stdlib.h>
#include <time.h>
#include "base/logging.h"
#include "base/thread_local_storage.h"
#include "base/time.h"
#include "base/win_util.h"
namespace rand_util {
// TODO(evanm): don't rely on static initialization.
// Using TLS since srand() needs to be called once in each thread.
TLSSlot g_tls_index;
int RandInt(int min, int max) {
if (g_tls_index.Get() == 0) {
g_tls_index.Set(reinterpret_cast<void*>(1));
TimeDelta now = TimeTicks::UnreliableHighResNow() - TimeTicks();
unsigned int seed = static_cast<unsigned int>(now.InMicroseconds());
srand(seed);
}
// From the rand man page, use this instead of just rand() % max, so that the
// higher bits are used.
return min + static_cast<int>(static_cast<double>(max - min + 1) *
(::rand() / (RAND_MAX + 1.0)));
}
int RandIntSecure(int min, int max) {
if (win_util::GetWinVersion() < win_util::WINVERSION_XP) {
// rand_s needs XP and later.
return RandInt(min, max);
}
unsigned int number;
errno_t rv = rand_s(&number);
DCHECK(rv == 0) << "rand_s failed with error " << rv;
// From the rand man page, use this instead of just rand() % max, so that the
// higher bits are used.
return min + static_cast<int>(static_cast<double>(max - min + 1.0) *
(number / (UINT_MAX + 1.0)));
}
} // namespace rand_util
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