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//
// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
// getrandom is not as nice as arc4random, but on platforms where it
// exists and arc4random does not, we should use it.
//
// getrandom will block only if the urandom device is not seeded yet.
// That can only happen during very early boot (earlier than we should
// normally be running. This is the only time it can fail with correct
// arguments, and then only if it is interrupted with a signal.
#include <stddef.h>
#include <sys/random.h>
#include "core/nng_impl.h"
#ifdef NNG_HAVE_GETRANDOM
uint32_t
nni_random(void)
{
uint32_t val;
// Documentation claims that as long as we are not using
// GRND_RANDOM and buflen < 256, this should never fail.
// The exception here is that we could fail if for some
// reason we got a signal while blocked at very early boot
// (i.e. /dev/urandom was not yet seeded).
if (getrandom(&val, sizeof(val), 0) != sizeof(val)) {
nni_panic("getrandom failed");
}
return (val);
}
#endif
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