UT/UT_NamedPipe.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * Produced by:
 *      Mark Elendt
 *      Side Effects Software Inc
 *      477 Richmond Street West
 *      Toronto, Ontario
 *      Canada   M5V 3E7
 *      416-504-9876
 *
 * NAME:        UT_NamedPipe.h ( UT Library, C++)
 *
 * COMMENTS:    This is a read pipe which gets around the problem of having a
 *              broken pipe if you close before reading all of the input from
 *              the pipe command.
 */

#ifndef __UT_NamedPipe__
#define __UT_NamedPipe__

#include "UT_API.h"
#include "UT_String.h"

#if defined(LINUX) || defined(MBSD)
    #include <stdio.h>
#endif

class UT_API UT_NamedPipe {
public:
     explicit UT_NamedPipe(int *filehandle);

     // If the pipe is open and destructed, the process will be killed.
    ~UT_NamedPipe();

    // Returns 1 if the pipe is open, 0 otherwise.
    int          isOpen();
    
    // Create a named pipe of the given name. Returns 0 on error, 1 on success.
    // Created pipes are all write-only.
    int          create(const char *filename);

    // Open a named pipe ofh the given name. Returns 0 on error, 1 on success.
    // Opened pipes are all read only.
    int          open(const char *filename);

    // Close the pipe.
    void         close();

    // Read up to the specified number of bytes. Returns the number of bytes
    // actually read. This call never blocks.
    int          read(char *data, int len);

    // Prepare named pipe for writing. Call this before doing a block
    // of writes. Under NT it makes sure the pipe is connected. Does
    // nothing under SGI.
    void         prepWrite();
    
    // Write the specified number of bytes. Returns the number of bytes
    // actually read. This call blocks until all bytes have been written.
    int          write(const char *data, int len);

    // Flush input or output.
    void         flush();
    
    // Returns 1 if there is data to be read, 0 if not, and less
    // than 0 if error.
    int          dataAvailable();

private:

    int          *myFileHandle;

    int          myCreated;
    UT_String    myFileName;
    int          myBytePending;
    char         myNextByte;
#ifndef WIN32
    FILE        *myPipe;
#endif
};

#endif

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