.\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk>
.\"
.\" SPDX-License-Identifier: LGPL-2.0-or-later
.\"
.TH io_uring_prep_waitid 3 "July 14, 2023" "liburing-2.5" "liburing Manual"
.SH NAME
io_uring_prep_waitid \- prepare a waitid request
.SH SYNOPSIS
.nf
.B #include <sys/wait.h>
.B #include <liburing.h>
.PP
.BI "void io_uring_prep_waitid(struct io_uring_sqe *" sqe ","
.BI "                          idtype_t " idtype ","
.BI "                          id_t " id ","
.BI "                          siginfo_t *" infop ","
.BI "                          int " options ","
.BI "                          unsigned int " flags ");"
.fi
.SH DESCRIPTION
.PP
The
.BR io_uring_prep_waitid (3)
function prepares a waitid request. The submission queue entry
.I sqe
is setup to use the
.I idtype
and
.I id
arguments select the child(ren), and
.I options
to specify the child state changes to wait for. Upon successful
return, it fills
.I infop
with information of the child process, if any.
.I flags
is io_uring specific modifier flags. They are currently unused, and hence
.B 0
should be passed.

This function prepares an async
.BR waitid (2)
request. See that man page for details.

.SH RETURN VALUE
None
.SH ERRORS
The CQE
.I res
field will contain the result of the operation. See the related man page for
details on possible values. Note that where synchronous system calls will return
.B -1
on failure and set
.I errno
to the actual error value, io_uring never uses
.IR errno .
Instead it returns the negated
.I errno
directly in the CQE
.I res
field.
.SH SEE ALSO
.BR io_uring_get_sqe (3),
.BR io_uring_submit (3),
.BR waitid (2)