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.\" $FreeBSD: head/lib/libc/sys/aio_cancel.2 267774 2014-06-23 08:25:03Z bapt $
.\"
.Dd January 19, 2000
.Dt AIO_CANCEL 2
.Os
.Sh NAME
.Nm aio_cancel
.Nd cancel an outstanding asynchronous I/O operation (REALTIME)
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In aio.h
.Ft int
.Fn aio_cancel "int fildes" "struct aiocb *iocb"
.Sh DESCRIPTION
The
.Fn aio_cancel
system call cancels the outstanding asynchronous
I/O request for the file descriptor specified in
.Fa fildes .
If
.Fa iocb
is specified, only that specific asynchronous I/O request is cancelled.
.Pp
Normal asynchronous notification occurs for cancelled requests.
Requests complete with an error result of
.Er ECANCELED .
.Sh RESTRICTIONS
The
.Fn aio_cancel
system call does not cancel asynchronous I/O requests for raw disk devices.
The
.Fn aio_cancel
system call will always return
.Dv AIO_NOTCANCELED
for file descriptors associated with raw disk devices.
.Sh RETURN VALUES
The
.Fn aio_cancel
system call returns -1 to indicate an error, or one of the following:
.Bl -tag -width Dv
.It Bq Dv AIO_CANCELED
All outstanding requests meeting the criteria specified were cancelled.
.It Bq Dv AIO_NOTCANCELED
Some requests were not cancelled, status for the requests should be
checked with
.Xr aio_error 2 .
.It Bq Dv AIO_ALLDONE
All of the requests meeting the criteria have finished.
.El
.Sh ERRORS
An error return from
.Fn aio_cancel
indicates:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa fildes
argument
is an invalid file descriptor.
.El
.Sh SEE ALSO
.Xr aio_error 2 ,
.Xr aio_read 2 ,
.Xr aio_return 2 ,
.Xr aio_suspend 2 ,
.Xr aio_write 2 ,
.Xr aio 4
.Sh STANDARDS
The
.Fn aio_cancel
system call is expected to conform to the
.St -p1003.1
standard.
.Sh HISTORY
The
.Fn aio_cancel
system call first appeared in
.Fx 3.0 .
The first functional implementation of
.Fn aio_cancel
appeared in
.Fx 4.0 .
.Sh AUTHORS
.An -nosplit
This
manual page was originally written by
.An Wes Peters Aq Mt wes@softweyr.com .
.An Christopher M Sedore Aq Mt cmsedore@maxwell.syr.edu
updated it when
.Fn aio_cancel
was implemented for
.Fx 4.0 .