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.Dd June 2, 1999
.Dt AIO_SUSPEND 2
.Os
.Sh NAME
.Nm aio_suspend
.Nd suspend until asynchronous I/O operations or timeout complete (REALTIME)
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In aio.h
.Ft int
.Fn aio_suspend "const struct aiocb * const iocbs[]" "int niocb" "const struct timespec * timeout"
.Sh DESCRIPTION
The
.Fn aio_suspend
function suspends the calling process until at least one of the
specified asynchronous I/O requests have completed, a signal is
delivered, or the
.Fa timeout
has passed.
.Pp
.Fa iocbs
is an array of
.Fa niocb
pointers to asynchronous I/O requests.  Array members containing
NULL will be silently ignored.
.Pp
If
.Fa timeout
is a non-nil pointer, it specifies a maximum interval to suspend.
If
.Fa timeout
is a nil pointer, the suspend blocks indefinitely.  To effect a
poll, the
.Fa timeout
should point to a zero-value timespec structure.
.Sh RETURN VALUES
If one or more of the specified asynchronous I/O requests have
completed,
.Fn aio_suspend
returns 0.  Otherwise it returns -1 and sets
.Va errno
to indicate the error, as enumerated below.
.Sh ERRORS
The
.Fn aio_suspend
function will fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
the
.Fa timeout
expired before any I/O requests completed.
.It Bq Er EINVAL
.Fa iocbs
contains more than
.Dv AIO_LISTIO_MAX
asynchronous I/O requests, or at least one of the requests is not
valid.
.It Bq Er EINTR
the suspend was interrupted by a signal.
.El
.Sh KERNEL OPTIONS
The following kernel configuration option
(see
.Xr config 8 )
is required:
.Pp
.Dl "options VFS_AIO"
.Pp
If you do not want AIO support included in the kernel, but
want to use it occasionally, do not add the
.Dv VFS_AIO
option.  Instead, load the
.Nm aio
module as desired:
.Pp
.Dl kldload aio
.Pp
.Sh SEE ALSO
.Xr aio 4 ,
.Xr aio_cancel 2 ,
.Xr aio_error 2 ,
.Xr aio_return 2 ,
.Xr aio_waitcomplete 2 ,
.Xr aio_write 2 ,
.Xr config 8 ,
.Xr kldload 8 ,
.Xr kldunload 8
.Sh STANDARDS
.Fn aio_suspend
is expected to conform to the
.St -p1003.2
standard.
.Sh HISTORY
The
.Nm
function first appeared in
.Fx 3.0 .
.Sh AUTHORS
This
manual page was written by
.An Wes Peters Aq wes@softweyr.com .