63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
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/* $OpenBSD: getentropy_freebsd.c,v 1.3 2016/08/07 03:27:21 tb Exp $ */
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/*
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* Copyright (c) 2014 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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* Copyright (c) 2014 Brent Cook <bcook@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* Emulation of getentropy(2) as documented at:
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* http://man.openbsd.org/getentropy.2
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*/
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#include <sys/types.h>
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#include <sys/sysctl.h>
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#include <errno.h>
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#include <stddef.h>
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/*
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* Derived from lib/libc/gen/arc4random.c from FreeBSD.
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*/
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static size_t
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getentropy_sysctl(u_char *buf, size_t size)
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{
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int mib[2];
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size_t len, done;
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mib[0] = CTL_KERN;
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mib[1] = KERN_ARND;
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done = 0;
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do {
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len = size;
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if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
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return (done);
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done += len;
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buf += len;
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size -= len;
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} while (size > 0);
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return (done);
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}
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int
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getentropy(void *buf, size_t len)
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{
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if (len <= 256 && getentropy_sysctl(buf, len) == len)
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return (0);
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errno = EIO;
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return (-1);
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}
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