71 lines
1.4 KiB
C++
71 lines
1.4 KiB
C++
/* getentropy.cc: getentropy/getrandmom functions
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This file is part of Cygwin.
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This software is a copyrighted work licensed under the terms of the
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Cygwin license. Please consult the file "CYGWIN_LICENSE" for
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details. */
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#include "winsup.h"
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#include <ntsecapi.h>
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#include <sys/param.h>
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#include <sys/random.h>
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#include "cygtls.h"
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#include "ntdll.h"
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extern "C" int
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getentropy (void *ptr, size_t len)
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{
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/* Per BSD man page: The maximum buffer size permitted is 256 bytes.
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If buflen exceeds this, an error of EIO will be indicated. */
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if (len > 256)
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{
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debug_printf ("len (%U) > 256", len);
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set_errno (EIO);
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return -1;
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}
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__try
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{
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if (!RtlGenRandom (ptr, len))
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{
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debug_printf ("RtlGenRandom() = FALSE");
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set_errno (EIO);
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return -1;
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}
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}
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__except (EFAULT)
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{
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return -1;
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}
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__endtry
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return 0;
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}
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extern "C" ssize_t
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getrandom (void *ptr, size_t len, unsigned int flags)
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{
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if (flags & ~(GRND_NONBLOCK | GRND_RANDOM))
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{
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debug_printf ("invalid flags: %y", flags);
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set_errno (EINVAL);
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return -1;
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}
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/* Max. bytes returned by Linux call. */
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len = MIN (len, (flags & GRND_RANDOM) ? 512 : 33554431);
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__try
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{
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if (!RtlGenRandom (ptr, len))
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{
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debug_printf ("RtlGenRandom() = FALSE");
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set_errno (EIO);
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return -1;
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}
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}
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__except (EFAULT)
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{
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return -1;
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}
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__endtry
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return len;
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}
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