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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 dif-
       fer (consult 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 particu-
       lar  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  [ECAN-
       CELED]  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  asyn-
       chronous 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 opera-
       tion(s) were canceled. The value AIO_NOTCANCELED shall be returned if at least  one  of  the  requested  opera-
       tion(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_cancel() 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. Otherwise, the function shall return -1 and set errno to indi-
       cate 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
       implementations.

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, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions Issue 6, Copyright (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 Stan-
       dard, the original IEEE and The Open Group Standard is the referee  document.  The  original  Standard  can  be
       obtained online at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                       AIO_CANCEL(3P)