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NAME

     aio_cancel - cancel an outstanding asynchronous I/O operation (REALTIME)

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <aio.h>

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

DESCRIPTION

     The aio_cancel() system call cancels the outstanding asynchronous I/O
     request for the file descriptor specified in fildes.  If iocb is
     specified, only that specific asynchronous I/O request is cancelled.

     Normal asynchronous notification occurs for cancelled requests.  Requests
     complete with an error result of ECANCELED.

RESTRICTIONS

     The aio_cancel() system call does not cancel asynchronous I/O requests
     for raw disk devices.  The aio_cancel() system call will always return
     AIO_NOTCANCELED for file descriptors associated with raw disk devices.

RETURN VALUES

     The aio_cancel() system call returns -1 to indicate an error, or one of
     the following:

     [AIO_CANCELED]
                   All outstanding requests meeting the criteria specified
                   were cancelled.

     [AIO_NOTCANCELED]
                   Some requests were not cancelled, status for the requests
                   should be checked with aio_error(2).

     [AIO_ALLDONE]
                   All of the requests meeting the criteria have finished.

ERRORS

     An error return from aio_cancel() indicates:

     [EBADF]            The fildes argument is an invalid file descriptor.

SEE ALSO

     aio_error(2), aio_read(2), aio_return(2), aio_suspend(2), aio_write(2),
     aio(4)

STANDARDS

     The aio_cancel() system call is expected to conform to the IEEE Std
     1003.1 (“POSIX.1”) standard.

HISTORY

     The aio_cancel() system call first appeared in FreeBSD 3.0.  The first
     functional implementation of aio_cancel() appeared in FreeBSD 4.0.

AUTHORS

     This manual page was originally written by Wes Peters 〈wes@softweyr.com〉.
     Christopher M Sedore 〈cmsedore@maxwell.syr.edu〉 updated it when
     aio_cancel() was implemented for FreeBSD 4.0.