55 lines
2.7 KiB
C
55 lines
2.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/bits.h"
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#include "libc/dce.h"
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#include "libc/rand/rand.h"
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#include "libc/str/str.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/calls.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/sysv/consts/at.h"
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#include "libc/sysv/consts/nr.h"
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#include "libc/sysv/consts/o.h"
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/**
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* Reads random bytes from system pseudo random number api.
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* @return 0 on success or -1 w/ errno
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*/
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int devrand(void *buf, size_t size) {
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int fd;
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size_t got;
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ssize_t rc;
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unsigned char *p, *pe;
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fd = -1;
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if (IsWindows()) return enosys();
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if ((fd = openat$sysv(AT_FDCWD, "/dev/urandom", O_RDONLY, 0)) == -1) {
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return -1;
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}
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p = buf;
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pe = p + size;
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while (p < pe) {
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if ((rc = read$sysv(fd, p, pe - p)) == -1) break;
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if (!(got = (size_t)rc)) break;
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p += got;
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}
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close$sysv(fd);
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return p == pe ? 0 : -1;
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}
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