.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
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.TH AIO_CANCEL 3 2015-03-02  "" "Linux Programmer's Manual"
.SH NAME
aio_cancel \- cancel an outstanding asynchronous I/O request
.SH SYNOPSIS
.B "#include <aio.h>"
.PP
.BI "int aio_cancel(int " fd ", struct aiocb *" aiocbp );
.PP
Link with \fI\-lrt\fP.
.SH DESCRIPTION
The
.BR aio_cancel ()
function attempts to cancel outstanding asynchronous I/O requests
for the file descriptor
.IR fd .
If
.I aiocbp
is NULL, all such requests are canceled.
Otherwise, only the request
described by the control block pointed to by
.I aiocbp
is canceled.
(See
.BR aio (7)
for a description of the
.I aiocb
structure.)
.PP
Normal asynchronous notification occurs for canceled requests (see
.BR aio (7)
and
.BR sigevent (7)).
The request return status
.RB ( aio_return (3))
is set to \-1, and the request error status
.RB ( aio_error (3))
is set to
.BR ECANCELED .
The control block of requests that cannot be canceled is not changed.
.PP
If the request could not be canceled,
then it will terminate in the usual way after performing the I/O operation.
(In this case,
.BR aio_error (3)
will return the status
.BR EINPROGRESSS .)
.PP
If
.I aiocbp
is not NULL, and
.I fd
differs from the file descriptor with which the asynchronous operation
was initiated, unspecified results occur.
.PP
Which operations are cancelable is implementation-defined.
.\" FreeBSD: not those on raw disk devices.
.SH RETURN VALUE
The
.BR aio_cancel ()
function returns one of the following values:
.TP
.B AIO_CANCELED
All requests were successfully canceled.
.TP
.B AIO_NOTCANCELED
At least one of the
requests specified was not canceled because it was in progress.
In this case, one may check the status of individual requests using
.BR aio_error (3).
.TP
.B AIO_ALLDONE
All requests had already been completed before the call.
.TP
\-1
An error occurred.
The cause of the error can be found by inspecting
.IR errno .
.SH ERRORS
.TP
.B EBADF
.I fd
is not a valid file descriptor.
.TP
.B ENOSYS
.BR aio_cancel ()
is not implemented.
.SH VERSIONS
The
.BR aio_cancel ()
function is available since glibc 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR aio_cancel ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH EXAMPLE
See
.BR aio (7).
.SH SEE ALSO
.BR aio_error (3),
.BR aio_fsync (3),
.BR aio_read (3),
.BR aio_return (3),
.BR aio_suspend (3),
.BR aio_write (3),
.BR lio_listio (3),
.BR aio (7)
.SH COLOPHON
This page is part of release 4.16 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.