49 lines
1.7 KiB
C
49 lines
1.7 KiB
C
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/* Copyright (c) 2016 Phoenix Systems
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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SUCH DAMAGE.*/
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <unistd.h>
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#define DEV_RANDOM "/dev/random"
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#define MAX_ENTROPY 256
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int getentropy(void *buf, size_t buflen)
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{
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if (buflen > MAX_ENTROPY) {
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errno = -EIO;
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return -1;
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}
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int ret = -1;
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int fd = open(DEV_RANDOM, O_RDONLY);
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if (fd >= 0) {
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ret = read(fd, buf, buflen);
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close(fd);
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}
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return (ret > 0) ? 0 : -1;
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}
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