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52 lines
1.4 KiB
C
52 lines
1.4 KiB
C
/* Fill a buffer with random bytes.
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Copyright 2020-2022 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 3 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert. */
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#include <config.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/random.h>
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/* Overwrite BUFFER with random data. BUFFER contains LENGTH bytes.
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LENGTH must be at most 256. Return 0 on success, -1 (setting
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errno) on failure. */
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int
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getentropy (void *buffer, size_t length)
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{
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char *buf = buffer;
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if (length <= 256)
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for (;;)
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{
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ssize_t bytes;
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if (length == 0)
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return 0;
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while ((bytes = getrandom (buf, length, 0)) < 0)
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if (errno != EINTR)
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return -1;
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if (bytes == 0)
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break;
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buf += bytes;
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length -= bytes;
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}
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errno = EIO;
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return -1;
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}
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