xref: /freebsd/lib/libc/gen/sysctlbyname.c (revision 4cf49a43559ed9fdad601bdcccd2c55963008675)
1 /*
2  * ----------------------------------------------------------------------------
3  * "THE BEER-WARE LICENSE" (Revision 42):
4  * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
5  * can do whatever you want with this stuff. If we meet some day, and you think
6  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
7  * ----------------------------------------------------------------------------
8  *
9  * $FreeBSD$
10  *
11  */
12 #include <sys/types.h>
13 #include <sys/sysctl.h>
14 #include <string.h>
15 
16 int
17 sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *newp,
18 	     size_t newlen)
19 {
20 	int name2oid_oid[2];
21 	int real_oid[CTL_MAXNAME+2];
22 	int error;
23 	size_t oidlen;
24 
25 	name2oid_oid[0] = 0;	/* This is magic & undocumented! */
26 	name2oid_oid[1] = 3;
27 
28 	oidlen = sizeof(real_oid);
29 	error = sysctl(name2oid_oid, 2, real_oid, &oidlen, (void *)name,
30 		       strlen(name));
31 	if (error < 0)
32 		return error;
33 	oidlen /= sizeof (int);
34 	error = sysctl(real_oid, oidlen, oldp, oldlenp, newp, newlen);
35 	return (error);
36 }
37 
38