.\" Copyright (c) 1999 Christopher M Sedore.
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.\" $FreeBSD: releng/12.0/lib/libc/sys/aio_waitcomplete.2 297167 2016-03-21 21:37:33Z jhb $
.\"
.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 .