aiocb(5)                                                    aiocb(5)


       NAME
             aiocb - Asynchronous I/O Control Block

       SYNOPSIS
             cc [options] -D_REENTRANT file -lthread
             #include <aio.h>

       DESCRIPTION
             aiocb specifies the asynchronous I/O control block that is
             used by the asynchronous I/O interface routines.

             The asynchronous I/O routines pass information with the
             request and receive completion status information after the
             I/O operation has completed.  An asynchronous I/O control
             block structure aiocb is used to specify input parameters and
             receive completion status information for asynchronous I/O
             requests.  This structure is defined in aio.h and includes the
             following members:

                int             aio_fildes;      /* file descriptor          */
                volatile void  *aio_buf;         /* buffer location          */
                size_t          aio_nbytes;      /* length of transfer       */
                off_t           aio_offset;      /* file offset              */
                int             aio_reqprio;     /* request priority offset  */
                struct sigevent aio_sigevent;    /* signal number and offset */
                int             aio_lio_opcode;  /* listio operation         */
                int             aio_flags;       /* flags                    */

             The structure members aio_fildes, aio_buf, and aio_nbytes  are
             the  same as the fildes, buf, and nbytes arguments to read and
             write.  With aio_read, for example, the caller wishes to  read
             aio_nbytes  from  the file associated with aio_fildes into the
             buffer pointed  to  by  aio_buf.   All  appropriate  structure
             members should be set by the caller when aio_read or aio_write
             is called.

             The aio_sigevent member defines the notification method to  be
             used  on  I/O  completion.   If  aio_sigevent.sigev_notify  is
             SIGEV_NONE, no notification is posted on I/O  completion,  but
             the  error  status for the operation and the return status for
             the operation shall be appropriately set.

             You may set the AIO_RAW flag bit in  the  aio_flags  structure
             member when the asynchronous I/O is being done to a raw device
             partition.  When the AIO_RAW flag bit is set, asynchronous I/O
             might  possibly  be more efficient.  Since asynchronous I/O is


                           Copyright 1994 Novell, Inc.               Page 1

      aiocb(5)                                                    aiocb(5)


            restricted to raw device partitions  on  SVR4.2,  asynchronous
            I/O  always behaves as if AIO_RAW was set.  On SVR4.2, setting
            the AIO_RAW flag bit is  required.  If  it  is  not  set,  all
            requests,  such as aio_read and aio_write should return -1 and
            set errno to EINVAL.

            To insure forward  compatibility,  you  must  set  all  unused
            fields  of  the  aiocb structure to zero.  This can be done by
            using calloc [see malloc(3C)] to allocate the structure.   The
            aio_reqprio  and  aio_lio_opcode  fields should be set to zero
            for applications developed under SVR4.2.

      REFERENCES
            aio_cancel(3aio), aio_error(3aio), aio_read(3aio),
            aio_suspend(3aio), aio_write(3aio), malloc(3C), read(2),
            write(2)

      NOTICES
            This page is derived from IEEE Draft Standard P1003.4/D14.
            See copyright page for further information.




























                          Copyright 1994 Novell, Inc.               Page 2