.\" Copyright (C) 2025 Jens Axboe <axboe@kernel.dk>
.\"
.\" SPDX-License-Identifier: LGPL-2.0-or-later
.\"
.TH io_uring_prep_epoll_ctl 3 "January 18, 2025" "liburing-2.4" "liburing Manual"
.SH NAME
io_uring_prep_epoll_ctl \- prepare an epoll_ctl request
.SH SYNOPSIS
.nf
.B #include <liburing.h>
.PP
.BI "void io_uring_prep_epoll_ctl(struct io_uring_sqe *" sqe ","
.BI "                             int " epfd ","
.BI "                             int " fd ","
.BI "                             int " op ","
.BI "                             const struct epoll_event *" ev ");"
.fi
.SH DESCRIPTION
.PP
The
.BR io_uring_prep_epoll_ctl (3)
function prepares an epoll control request. The submission queue entry
.I sqe
is setup to use the epoll instance referred to by
.IR epfd ,
performing the operation
.I op
on the file descriptor
.IR fd .
The
.I ev
argument points to an
.I epoll_event
structure as defined in
.BR epoll_ctl (2).

The
.I op
argument can be one of:
.TP
.B EPOLL_CTL_ADD
Add
.I fd
to the epoll instance.
.TP
.B EPOLL_CTL_MOD
Modify the settings for
.IR fd .
.TP
.B EPOLL_CTL_DEL
Remove
.I fd
from the epoll instance.
.I ev
is ignored for this operation.

This function prepares an async
.BR epoll_ctl (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, 0 on success. On error,
a negative errno value is returned. See
.BR epoll_ctl (2)
for possible error values.
.SH SEE ALSO
.BR io_uring_get_sqe (3),
.BR io_uring_submit (3),
.BR io_uring_prep_epoll_wait (3),
.BR epoll_ctl (2)