xref: /freebsd/lib/libc/gen/sched_getaffinity.c (revision 8881d206f4e68b564c2c5f50fc717086fc3e827a)
1 /*-
2  * Copyright (c) 2021 The FreeBSD Foundation
3  *
4  * This software were developed by Konstantin Belousov <kib@FreeBSD.org>
5  * under sponsorship from the FreeBSD Foundation.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <errno.h>
30 #include <sched.h>
31 #include <string.h>
32 
33 int
34 sched_getaffinity(pid_t pid, size_t cpusetsz, cpuset_t *cpuset)
35 {
36 	/*
37 	 * Be more Linux-compatible:
38 	 * - return EINVAL in passed size is less than size of cpuset_t
39 	 *   in advance, instead of ERANGE from the syscall
40 	 * - if passed size is larger than the size of cpuset_t, be
41 	 *   permissive by claming it back to sizeof(cpuset_t) and
42 	 *   zeroing the rest.
43 	 */
44 	if (cpusetsz < sizeof(cpuset_t)) {
45 		errno = EINVAL;
46 		return (-1);
47 	}
48 	if (cpusetsz > sizeof(cpuset_t)) {
49 		memset((char *)cpuset + sizeof(cpuset_t), 0,
50 		    cpusetsz - sizeof(cpuset_t));
51 		cpusetsz = sizeof(cpuset_t);
52 	}
53 
54 	return (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID,
55 	    pid == 0 ? -1 : pid, cpusetsz, cpuset));
56 }
57