mlock_helper.c revision 327855 
1/*-
2 * Copyright (C) 2016 Bryan Drewery <bdrewery@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27/*
28 * Helper for mlock(3) to avoid EAGAIN errors
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/11/lib/libc/tests/sys/mlock_helper.c 327855 2018-01-12 00:25:56Z asomers $");
33
34#include <sys/types.h>
35#include <sys/sysctl.h>
36
37#include <atf-c.h>
38#include <errno.h>
39#include <stdio.h>
40#include <limits.h>
41
42#define	VM_MAX_WIRED "vm.max_wired"
43
44static void
45vm_max_wired_sysctl(int *old_value, int *new_value)
46{
47	size_t old_len;
48	size_t new_len = (new_value == NULL ? 0 : sizeof(int));
49
50	if (old_value == NULL)
51		printf("Setting the new value to %d\n", *new_value);
52	else {
53		ATF_REQUIRE_MSG(sysctlbyname(VM_MAX_WIRED, NULL, &old_len,
54		    new_value, new_len) == 0,
55		    "sysctlbyname(%s) failed: %s", VM_MAX_WIRED, strerror(errno));
56	}
57
58	ATF_REQUIRE_MSG(sysctlbyname(VM_MAX_WIRED, old_value, &old_len,
59	    new_value, new_len) == 0,
60	    "sysctlbyname(%s) failed: %s", VM_MAX_WIRED, strerror(errno));
61
62	if (old_value != NULL)
63		printf("Saved the old value (%d)\n", *old_value);
64}
65
66void
67set_vm_max_wired(int new_value)
68{
69	FILE *fp;
70	int old_value;
71
72	fp = fopen(VM_MAX_WIRED, "w");
73	if (fp == NULL) {
74		atf_tc_skip("could not open %s for writing: %s",
75		    VM_MAX_WIRED, strerror(errno));
76		return;
77	}
78
79	vm_max_wired_sysctl(&old_value, NULL);
80
81	ATF_REQUIRE_MSG(fprintf(fp, "%d", old_value) > 0,
82	    "saving %s failed", VM_MAX_WIRED);
83
84	fclose(fp);
85
86	vm_max_wired_sysctl(NULL, &new_value);
87}
88
89void
90restore_vm_max_wired(void)
91{
92	FILE *fp;
93	int saved_max_wired;
94
95	fp = fopen(VM_MAX_WIRED, "r");
96	if (fp == NULL) {
97		perror("fopen failed\n");
98		return;
99	}
100
101	if (fscanf(fp, "%d", &saved_max_wired) != 1) {
102		perror("fscanf failed\n");
103		fclose(fp);
104		return;
105	}
106
107	fclose(fp);
108	printf("old value in %s: %d\n", VM_MAX_WIRED, saved_max_wired);
109
110	if (saved_max_wired == 0) /* This will cripple the test host */
111		return;
112
113	vm_max_wired_sysctl(NULL, &saved_max_wired);
114}
115