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random.cpp
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91 lines (80 loc) · 1.91 KB
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//===-------------------------- random.cpp --------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#if defined(_WIN32)
// Must be defined before including stdlib.h to enable rand_s().
#define _CRT_RAND_S
#include <stdio.h>
#endif
#include "random"
#include "system_error"
#ifdef __sun__
#define rename solaris_headers_are_broken
#endif
#if !defined(_WIN32)
#include <fcntl.h>
#include <unistd.h>
#endif // defined(_WIN32)
#include <errno.h>
_LIBCPP_BEGIN_NAMESPACE_STD
#if defined(_WIN32)
random_device::random_device(const string&)
{
}
random_device::~random_device()
{
}
unsigned
random_device::operator()()
{
unsigned r;
errno_t err = rand_s(&r);
if (err)
__throw_system_error(err, "random_device rand_s failed.");
return r;
}
#else
random_device::random_device(const string& __token)
: __f_(open(__token.c_str(), O_RDONLY))
{
if (__f_ < 0)
__throw_system_error(errno, ("random_device failed to open " + __token).c_str());
}
random_device::~random_device()
{
close(__f_);
}
unsigned
random_device::operator()()
{
unsigned r;
size_t n = sizeof(r);
char* p = reinterpret_cast<char*>(&r);
while (n > 0)
{
ssize_t s = read(__f_, p, n);
if (s == 0)
__throw_system_error(ENODATA, "random_device got EOF");
if (s == -1)
{
if (errno != EINTR)
__throw_system_error(errno, "random_device got an unexpected error");
continue;
}
n -= static_cast<size_t>(s);
p += static_cast<size_t>(s);
}
return r;
}
#endif // defined(_WIN32)
double
random_device::entropy() const _NOEXCEPT
{
return 0;
}
_LIBCPP_END_NAMESPACE_STD