1 /* $NetBSD: eventfd_read.c,v 1.1 2021/09/19 15:51:28 thorpej Exp $ */
2
3 /*-
4 * Copyright (c) 2020 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31 #include <sys/cdefs.h>
32 #if defined(LIBC_SCCS) && !defined(lint)
33 __RCSID("$NetBSD: eventfd_read.c,v 1.1 2021/09/19 15:51:28 thorpej Exp $");
34 #endif /* LIBC_SCCS and not lint */
35
36 #include "namespace.h"
37 #include <sys/types.h>
38 #include <sys/eventfd.h>
39 #include <errno.h>
40 #include <unistd.h>
41
42 int
eventfd_read(int efd,eventfd_t * valp)43 eventfd_read(int efd, eventfd_t *valp)
44 {
45 eventfd_t val;
46
47 switch (read(efd, &val, sizeof(val))) {
48 case -1:
49 return -1;
50
51 case sizeof(val):
52 *valp = val;
53 return 0;
54
55 default:
56 /* This should never happen, but... */
57 errno = EIO;
58 return -1;
59 }
60 }
61