random.h

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/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2019 National Institute of Advanced Industrial Science
 *                           and Technology (AIST)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 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 HOLDER 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
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
 
#ifndef RANDOM_H
#define RANDOM_H
 
#include <sys/types.h>
// for keystone-enclave v0.4 we saw the getrandom(2) function freeze, so we use srandom/random instead when we set `SEED` value.
#ifdef SEED
#include <stdlib.h>
#define getrandom seed_random
static ssize_t seed_random(void *buf, size_t buflen, unsigned int flags) {
    (flags); // not used
    const ssize_t ss = sizeof(unsigned int);
    unsigned int retval;
    unsigned int *b = (unsigned int*)buf;
    ssize_t idx = 0;
    srandom((unsigned int)SEED);
    while(buflen) {
        retval = random();
        buflen -= ss;
        b[idx++] = retval;
    }
    return idx*ss;
}
#else
#include <sys/random.h>
#endif
 
#endif /* RANDOM_H */