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