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//
// Pipe.h
//
// Library: Foundation
// Package: Processes
// Module: Pipe
//
// Definition of the Pipe class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_Pipe_INCLUDED
#define Foundation_Pipe_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/PipeImpl.h"
namespace Poco {
class Foundation_API Pipe
/// This class implements an anonymous pipe.
///
/// Pipes are a common method of inter-process communication -
/// on Unix, pipes are the oldest form of IPC.
///
/// A pipe is a half-duplex communication channel, which means
/// that data only flows in one direction.
/// Pipes have a read-end and a write-end. One process writes to
/// the pipe and another process reads the data written by
/// its peer.
/// Read and write operations are always synchronous. A read will
/// block until data is available and a write will block until
/// the reader reads the data.
///
/// The sendBytes() and readBytes() methods of Pipe are usually
/// used through a PipeOutputStream or PipeInputStream and are
/// not called directly.
///
/// Pipe objects have value semantics; the actual work is delegated
/// to a reference-counted PipeImpl object.
{
public:
typedef PipeImpl::Handle Handle; /// The read/write handle or file descriptor.
enum CloseMode /// used by close()
{
CLOSE_READ = 0x01, /// Close reading end of pipe.
CLOSE_WRITE = 0x02, /// Close writing end of pipe.
CLOSE_BOTH = 0x03 /// Close both ends of pipe.
};
Pipe();
/// Creates the Pipe.
///
/// Throws a CreateFileException if the pipe cannot be
/// created.
Pipe(const Pipe& pipe);
/// Creates the Pipe using the PipeImpl from another one.
~Pipe();
/// Closes and destroys the Pipe.
Pipe& operator = (const Pipe& pipe);
/// Releases the Pipe's PipeImpl and assigns another one.
int writeBytes(const void* buffer, int length);
/// Sends the contents of the given buffer through
/// the pipe. Blocks until the receiver is ready
/// to read the data.
///
/// Returns the number of bytes sent.
///
/// Throws a WriteFileException if the data cannot be written.
int readBytes(void* buffer, int length);
/// Receives data from the pipe and stores it
/// in buffer. Up to length bytes are received.
/// Blocks until data becomes available.
///
/// Returns the number of bytes received, or 0
/// if the pipe has been closed.
///
/// Throws a ReadFileException if nothing can be read.
Handle readHandle() const;
/// Returns the read handle or file descriptor
/// for the Pipe. For internal use only.
Handle writeHandle() const;
/// Returns the write handle or file descriptor
/// for the Pipe. For internal use only.
void close(CloseMode mode = CLOSE_BOTH);
/// Depending on the argument, closes either the
/// reading end, the writing end, or both ends
/// of the Pipe.
private:
PipeImpl* _pImpl;
};
//
// inlines
//
inline int Pipe::writeBytes(const void* buffer, int length)
{
return _pImpl->writeBytes(buffer, length);
}
inline int Pipe::readBytes(void* buffer, int length)
{
return _pImpl->readBytes(buffer, length);
}
inline Pipe::Handle Pipe::readHandle() const
{
return _pImpl->readHandle();
}
inline Pipe::Handle Pipe::writeHandle() const
{
return _pImpl->writeHandle();
}
} // namespace Poco
#endif // Foundation_Pipe_INCLUDED
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