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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/config.h"
#if defined(MONGO_CONFIG_HAVE_MEMSET_S)
#define __STDC_WANT_LIB_EXT1__ 1
#endif
#include "mongo/platform/basic.h"
#include <cstring>
#include "mongo/util/assert_util.h"
namespace mongo {
void secureZeroMemory(void* mem, size_t size) {
if (mem == nullptr) {
fassert(28751, size == 0);
return;
}
#if defined(_WIN32)
// Windows provides a simple function for zeroing memory
SecureZeroMemory(mem, size);
#elif defined(MONGO_CONFIG_HAVE_EXPLICIT_BZERO)
// Gblic 2.25+, OpenBSD 5.5+ and FreeBSD 11.0+ offer explicit_bzero
explicit_bzero(mem, size);
#elif defined(MONGO_CONFIG_HAVE_MEMSET_S)
// Some C11 libraries provide a variant of memset which is guaranteed to not be optimized away
fassert(28752, memset_s(mem, size, 0, size) == 0);
#else
// fall back to using volatile pointer
// using volatile to disable compiler optimizations
volatile char* p = reinterpret_cast<volatile char*>(mem); // NOLINT
while (size--) {
*p++ = 0;
}
#endif
}
} // namespace mongo
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