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// **********************************************************************
//
// Copyright (c) 2003-2006 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************
#include <IceUtil/Random.h>
#ifdef _WIN32
// TODO
#else
# include <IceUtil/StaticMutex.h>
# include <sys/types.h>
# include <sys/stat.h>
# include <fcntl.h>
# include <unistd.h>
#endif
using namespace std;
IceUtil::RandomGeneratorException::RandomGeneratorException(const char* file, int line) :
Exception(file, line)
{
}
const char* IceUtil::RandomGeneratorException::_name = "IceUtil::RandomGeneratorException";
#ifndef _WIN32
//
// Unfortunately on Linux (at least up to 2.6.9), concurrent access to /dev/urandom
// can return the same value. Search for "Concurrent access to /dev/urandom" in the
// linux-kernel mailing list archive for additional details.
// Since /dev/urandom on other platforms is usually a port from Linux, this problem
// could be widespread. Therefore, we serialize access to /dev/urandom using a static
// mutex.
//
static IceUtil::StaticMutex staticMutex = ICE_STATIC_MUTEX_INITIALIZER;
static int fd = -1;
namespace
{
//
// Close fd at exit
//
class RandomCleanup
{
public:
~RandomCleanup()
{
IceUtil::StaticMutex::Lock lock(staticMutex);
if(fd != -1)
{
close(fd);
fd = -1;
}
}
};
static RandomCleanup uuidCleanup;
}
#endif
const string
IceUtil::RandomGeneratorException::ice_name() const
{
return _name;
}
IceUtil::Exception*
IceUtil::RandomGeneratorException::ice_clone() const
{
return new RandomGeneratorException(*this);
}
void
IceUtil::RandomGeneratorException::ice_throw() const
{
throw *this;
}
void
IceUtil::generateRandom(char* buffer, int size)
{
#ifdef _WIN32
//
// TODO: XXX
//
#else
int reads = 0;
size_t index = 0;
{
//
// Serialize access to /dev/urandom; see comment above.
//
IceUtil::StaticMutex::Lock lock(staticMutex);
if(fd == -1)
{
fd = open("/dev/urandom", O_RDONLY);
if (fd == -1)
{
assert(0);
throw RandomGeneratorException(__FILE__, __LINE__);
}
}
//
// Limit the number of attempts to 20 reads to avoid
// a potential "for ever" loop
//
while(reads <= 20 && index != static_cast<size_t>(size))
{
ssize_t bytesRead = read(fd, buffer + index, static_cast<size_t>(size) - index);
if(bytesRead == -1 && errno != EINTR)
{
int err = errno;
cerr << "Reading /dev/urandom returned " << strerror(err) << endl;
assert(0);
throw RandomGeneratorException(__FILE__, __LINE__);
}
else
{
index += bytesRead;
reads++;
}
}
}
if(index != static_cast<size_t>(size))
{
assert(0);
throw RandomGeneratorException(__FILE__, __LINE__);
}
#endif
}
int
IceUtil::random(int limit)
{
int r;
generateRandom(reinterpret_cast<char*>(&r), sizeof(int));
return r % limit;
}
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