mirror of
https://github.com/jart/cosmopolitan.git
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63 lines
2.9 KiB
C
63 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above 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 │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/blockcancel.internal.h"
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#include "libc/calls/syscall_support-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/strace.h"
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#include "libc/sysv/errfuns.h"
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int sys_getentropy(void *, size_t) asm("sys_getrandom");
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/**
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* Returns random seeding bytes, the POSIX way.
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*
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* @return 0 on success, or -1 w/ errno
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* @raise EFAULT if the `n` bytes at `p` aren't valid memory
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* @raise EIO is returned if more than 256 bytes are requested
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* @see getrandom()
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*/
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int getentropy(void *p, size_t n) {
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int rc;
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if (n > 256) {
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rc = eio();
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} else if ((!p && n)) {
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rc = efault();
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} else if (IsXnu() || IsOpenbsd()) {
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rc = sys_getentropy(p, n);
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} else {
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ssize_t got;
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BLOCK_CANCELATION;
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rc = 0;
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for (size_t i = 0; i < n; i += got) {
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got = __getrandom(p + i, n - i, 0);
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if (got == -1) {
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if (errno == EAGAIN || errno == EINTR) {
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got = 0;
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} else {
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rc = -1;
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break;
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}
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}
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}
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ALLOW_CANCELATION;
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}
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STRACE("getentropy(%p, %'zu) → %'ld% m", p, n, rc);
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return rc;
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}
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