AIO_CANCEL(3P)                                      POSIX Programmer's Manual                                     AIO_CANCEL(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       aio_cancel - cancel an asynchronous I/O request (REALTIME)

SYNOPSIS
       #include <aio.h>

       int aio_cancel(int fildes, struct aiocb *aiocbp);


DESCRIPTION
       The  aio_cancel()  function  shall  attempt to cancel one or more asynchronous I/O requests currently outstanding against
       file descriptor fildes. The aiocbp argument points to the asynchronous I/O control block for a particular request  to  be
       canceled. If aiocbp is NULL, then all outstanding cancelable asynchronous I/O requests against fildes shall be canceled.

       Normal asynchronous notification shall occur for asynchronous I/O operations that are successfully canceled. If there are
       requests that cannot be canceled, then the normal asynchronous completion process shall take  place  for  those  requests
       when they are completed.

       For  requested operations that are successfully canceled, the associated error status shall be set to [ECANCELED] and the
       return status shall be -1. For requested operations that are not successfully canceled, the aiocbp shall not be  modified
       by aio_cancel().

       If  aiocbp  is  not  NULL, then if fildes does not have the same value as the file descriptor with which the asynchronous
       operation was initiated, unspecified results occur.

       Which operations are cancelable is implementation-defined.

RETURN VALUE
       The aio_cancel() function shall return the value AIO_CANCELED to the calling process if the requested  operation(s)  were
       canceled.  The  value  AIO_NOTCANCELED shall be returned if at least one of the requested operation(s) cannot be canceled
       because it is in progress. In this case, the state of the other operations, if any, referenced in the  call  to  aio_can-
       cel()  is not indicated by the return value of aio_cancel(). The application may determine the state of affairs for these
       operations by using aio_error(). The value AIO_ALLDONE is returned if all of the operations have already completed.  Oth-
       erwise, the function shall return -1 and set errno to indicate the error.

ERRORS
       The aio_cancel() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The  aio_cancel() function is part of the Asynchronous Input and Output option and need not be available on all implemen-
       tations.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       aio_read(), aio_write(), the Base Definitions volume of IEEE Std 1003.1-2001, <aio.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                AIO_CANCEL(3P)