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Pipe.h

//
// Pipe.h
//
// $Id: //poco/1.2/Foundation/include/Poco/Pipe.h#1 $
//
// Library: Foundation
// Package: Processes
// Module:  Pipe
//
// Definition of the Pipe class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Pipe_INCLUDED
#define Foundation_Pipe_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/PipeImpl.h"


namespace Poco {


00050 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.
      
00075       enum CloseMode /// used by close()
      {
            CLOSE_READ  = 0x01, /// Close reading end of pipe.
00078             CLOSE_WRITE = 0x02, /// Close writing end of pipe.
00079             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:
00130       PipeImpl* _pImpl;
};


//
// inlines
//
00137 inline int Pipe::writeBytes(const void* buffer, int length)
{
      return _pImpl->writeBytes(buffer, length);
}


00143 inline int Pipe::readBytes(void* buffer, int length)
{
      return _pImpl->readBytes(buffer, length);
}


00149 inline Pipe::Handle Pipe::readHandle() const
{
      return _pImpl->readHandle();
}


00155 inline Pipe::Handle Pipe::writeHandle() const
{
      return _pImpl->writeHandle();
}


} // namespace Poco


#endif // Foundation_Pipe_INCLUDED

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