ClickHouse/base/poco/Foundation/include/Poco/RandomStream.h

//
// RandomStream.h
//
// Library: Foundation
// Package: Crypt
// Module:  RandomStream
//
// Definition of class RandomInputStream.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_RandomStream_INCLUDED
#define Foundation_RandomStream_INCLUDED


#include <istream>
#include "Poco/BufferedStreamBuf.h"
#include "Poco/Foundation.h"


namespace Poco
{


class Foundation_API RandomBuf : public BufferedStreamBuf
/// This streambuf generates random data.
/// On Windows NT, the cryptographic API is used.
/// On Unix, /dev/random is used, if available.
/// Otherwise, a random number generator, some
/// more-or-less random data and a SHA-1 digest
/// is used to generate random data.
{
public:
    RandomBuf();
    ~RandomBuf();
    int readFromDevice(char * buffer, std::streamsize length);
};


class Foundation_API RandomIOS : public virtual std::ios
/// The base class for RandomInputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
    RandomIOS();
    ~RandomIOS();
    RandomBuf * rdbuf();

protected:
    RandomBuf _buf;
};


class Foundation_API RandomInputStream : public RandomIOS, public std::istream
/// This istream generates random data
/// using the RandomBuf.
{
public:
    RandomInputStream();
    ~RandomInputStream();
};


} // namespace Poco


#endif // Foundation_RandomStream_INCLUDED