ADDIOPROC(3A)                                       ADDIOPROC(3A)



  NAME
       #include <fcntl.h>

       AddIoProc, RemoveIoProc - Add and remove an asynchronous I/O
       procedure


  SYNOPSIS
       AddIoProc (fd, buf, size, func, errfunc, mode, line, arg)
       int fd;
       char *buf;
       int size;
       int (*func)();
       int (*errfunc)();
       int mode;
       int line;
       int arg;

       RemoveIoProc (fd)
       int fd;

  DESCRIPTION
       AddIoProc registers I/O procedures for doing asynchronous
       I/O on the file descriptor fd . I/O to or from this file
       will be done in the buffer buf , which can hold up to size
       bytes.  Normally, func will be called to indicate data
       transfer.  However, if there is an error, errfunc will be
       called instead.  They may, however, be the same function.
       The mode is either O_RDONLY or O_WRONLY for read or write
       mode.  In read mode, the boolean line is non-zero for
       reading line-by-line, otherwise func will be called only
       when the buffer is full, or there has been some exception on
       the file.  The boolean line flag is ignored for writing.
       When either func or errfunc is called, arg is passed to the
       function

       The calling sequence for both func and errfunc is as
       follows:

            int func (arg, fd, buf, len, error)


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  ADDIOPROC(3A)                                       ADDIOPROC(3A)



            int arg;
            int fd;
            char **pbuf;
            int len;
            int error;

       Arg and fd are the same as those passed originally to
       AddIoProc . The buffer is pointed to by the pointer pbuf is
       a pointer to the buffer pointer, and len is the number of
       bytes actually transferred.  If len is -1, an error
       occurred, and error will contain the system error number.
       The size of the buffer pointer to by pbuf is returned by
       func.  In read mode, func may return 0 to indicate that the
       remainder of the file should be ignored.  In either read or
       write mode, func may return -1 to indicate that the file
       descriptor has been closed and the io procedure removed by
       RemoveIoProc.

       When errfunc is called, len is always -1.  When func is
       called, len is always greater than or Thus, if func and
       errfunc are the same function, the value of len can be used
       to determine which occured.  If len is not -1, the value of
       error is not meaningful and should be ignored.

       The I/O handling routine is able to fully manage the
       buffering of the data through the pointer pbuf and the
       return value.  In read mode, the current data buffer can be
       saved and a different (perhaps dynamically allocated) buffer
       returned for subsequent data, even a different sized one.
       In write mode, another buffer with data already prepared may
       be presented for the subsequent write operation.

       RemoveIoProc removes the I/O procedure associated with the
       file descriptor fd.  The file should have been already
       closed.

  NOTES
       The Atari Application Library has higher level routines for
       handling common I/O cases, such as ReadFileData (3A). There
       are also outines for doing pipe I/O, such as OpenReadPipe


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  ADDIOPROC(3A)                                       ADDIOPROC(3A)



       (3A).

  SEE ALSO
       XtAddInputProc(3Xt), OpenReadPipe(3A), OpenWritePipe(3A),
       OpenFilter(3A), OpenFilter(3A), ReadFileData(3A),
       ReadFileLines(3A), ReadFileStrings(3A), ReadPipeData(3A),
       ReadPipeLines(3A), ReadPipeStrings(3A)



































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