.\" Copyright (c) 1999 Christopher M Sedore.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd March 21, 2016
.Dt AIO_WAITCOMPLETE 2
.Os
.Sh NAME
.Nm aio_waitcomplete
.Nd wait for the next completion of an aio request
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In aio.h
.Ft ssize_t
.Fn aio_waitcomplete "struct aiocb **iocbp" "struct timespec *timeout"
.Sh DESCRIPTION
The
.Fn aio_waitcomplete
system call waits for completion of an asynchronous I/O request.
Upon completion,
.Fn aio_waitcomplete
returns the result of the function and sets
.Fa iocbp
to point to the structure associated with the original request.
If an asynchronous I/O request is completed before
.Fn aio_waitcomplete
is called, it returns immediately with the completed request.
.Pp
If
.Fa timeout
is a non-NULL pointer, it specifies a maximum interval to wait for a
asynchronous I/O request to complete.
If
.Fa timeout
is a NULL pointer,
.Fn aio_waitcomplete
waits indefinitely.
To effect a poll, the
.Fa timeout
argument should be non-NULL, pointing to a zero-valued timeval structure.
.Pp
The
.Fn aio_waitcomplete
system call also serves the function of
.Fn aio_return ,
thus
.Fn aio_return
should not be called for the control block returned in
.Fa iocbp .
.Sh RETURN VALUES
If an asynchronous I/O request has completed,
.Fa iocbp
is set to point to the control block passed with the original request,
and the status is returned as described in
.Xr read 2 ,
.Xr write 2 ,
or
.Xr fsync 2 .
On failure,
.Fn aio_waitcomplete
returns
.Dv -1 ,
sets iocbp to
.Dv NULL
and sets
.Va errno
to indicate the error condition.
.Sh ERRORS
The
.Fn aio_waitcomplete
system call fails if:
.Bl -tag -width Er
.It Bq Er EINVAL
The specified time limit is invalid.
.It Bq Er EAGAIN
The process has not yet called
.Fn aio_read
or
.Fn aio_write .
.It Bq Er EINTR
A signal was delivered before the timeout expired and before any
asynchronous I/O requests completed.
.It Bq Er EWOULDBLOCK
.It Bq Er EINPROGRESS
The specified time limit expired before any asynchronous I/O requests
completed.
.El
.Sh SEE ALSO
.Xr aio_cancel 2 ,
.Xr aio_error 2 ,
.Xr aio_read 2 ,
.Xr aio_return 2 ,
.Xr aio_suspend 2 ,
.Xr aio_write 2 ,
.Xr fsync 2 ,
.Xr read 2 ,
.Xr write 2 ,
.Xr aio 4
.Sh STANDARDS
The
.Fn aio_waitcomplete
system call is a
.Fx Ns -specific
extension.
.Sh HISTORY
The
.Fn aio_waitcomplete
system call first appeared in
.Fx 4.0 .
.Sh AUTHORS
The
.Fn aio_waitcomplete
system call and this manual page were written by
.An Christopher M Sedore Aq Mt cmsedore@maxwell.syr.edu .
