lib/libc/gen/sysctlbyname.c

   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: src/lib/libc/gen/sysctlbyname.c,v 1.4 1999/08/27 23:59:01 peter Exp $
  10  * $DragonFly: src/lib/libc/gen/sysctlbyname.c,v 1.2 2003/06/17 04:26:42 dillon Exp $
  11  *
  12  */
  13 #include <sys/types.h>
  14 #include <sys/sysctl.h>
  15 #include <string.h>
  16
  17 int
  18 sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *newp,
  19              size_t newlen)
  20 {
  21         int name2oid_oid[2];
  22         int real_oid[CTL_MAXNAME+2];
  23         int error;
  24         size_t oidlen;
  25
  26         name2oid_oid[0] = 0;    /* This is magic & undocumented! */
  27         name2oid_oid[1] = 3;
  28
  29         oidlen = sizeof(real_oid);
  30         error = sysctl(name2oid_oid, 2, real_oid, &oidlen, (void *)name,
  31                        strlen(name));
  32         if (error < 0)
  33                 return error;
  34         oidlen /= sizeof (int);
  35         error = sysctl(real_oid, oidlen, oldp, oldlenp, newp, newlen);
  36         return (error);
  37 }
  38