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/* boost random_device.cpp implementation
*
* Copyright Jens Maurer 2000
* Distributed under the Boost Software License, Version 1.0. (See
* accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* $Id: random_device.cpp 24096 2004-07-27 03:43:34Z dgregor $
*
*/
#include <boost/nondet_random.hpp>
#include <string>
#include <cassert>
#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
// A definition is required even for integral static constants
const bool boost::random_device::has_fixed_range;
const boost::random_device::result_type boost::random_device::min_value;
const boost::random_device::result_type boost::random_device::max_value;
#endif
#ifdef __linux__
// the default is the unlimited capacity device, using some secure hash
// try "/dev/random" for blocking when the entropy pool has drained
const char * const boost::random_device::default_token = "/dev/urandom";
/*
* This uses the POSIX interface for unbuffered reading.
* Using buffered std::istream would consume entropy which may
* not actually be used. Entropy is a precious good we avoid
* wasting.
*/
#if defined(__GNUC__) && defined(_CXXRT_STD_NAME)
// I have severe difficulty to get the POSIX includes to work with
// -fhonor-std and Dietmar Khl's standard C++ library. Hack around that
// problem for now.
extern "C" {
static const int O_RDONLY = 0;
extern int open(const char *__file, int __oflag, ...);
extern int read(int __fd, __ptr_t __buf, size_t __nbytes);
extern int close(int __fd);
}
#else
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h> // open
#include <unistd.h> // read, close
#endif
#include <errno.h> // errno
#include <string.h> // strerror
#include <stdexcept> // std::invalid_argument
class boost::random_device::impl
{
public:
impl(const std::string & token) : path(token) {
fd = open(token.c_str(), O_RDONLY);
if(fd < 0)
error("cannot open");
}
~impl() { if(close(fd) < 0) error("could not close"); }
unsigned int next() {
unsigned int result;
long sz = read(fd, reinterpret_cast<char *>(&result), sizeof(result));
if(sz == -1)
error("error while reading");
else if(sz != sizeof(result)) {
errno = 0;
error("EOF while reading");
}
return result;
}
private:
void error(const std::string & msg) {
throw std::invalid_argument("boost::random_device: " + msg +
" random-number pseudo-device " + path +
": " + strerror(errno));
}
const std::string path;
int fd;
};
#endif // __linux__
boost::random_device::random_device(const std::string& token)
: pimpl(new impl(token))
{
assert((std::numeric_limits<result_type>::max)() == max_value);
}
boost::random_device::~random_device()
{
// the complete class impl is now visible, so we're safe
// (see comment in random.hpp)
delete pimpl;
}
double boost::random_device::entropy() const
{
return 10;
}
unsigned int boost::random_device::operator()()
{
return pimpl->next();
}
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