gen/FreeBSD/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  */
  10
  11 #include <sys/cdefs.h>
  12 __FBSDID("$FreeBSD: src/lib/libc/gen/sysctlbyname.c,v 1.5 2002/02/01 00:57:29 obrien Exp $");
  13
  14 #include <sys/types.h>
  15 #include <sys/sysctl.h>
  16 #include <string.h>
  17 #include <sys/errno.h>
  18 #include <TargetConditionals.h>
  19
  20 extern int __sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
  21                                         void *newp, size_t newlen);
  22 extern int
  23 __sysctlbyname(const char *name, size_t namelen, void *oldp, size_t *oldlenp, void *newp,
  24                            size_t newlen);
  25
  26 int
  27 sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *newp,
  28              size_t newlen)
  29 {
  30         int name2oid_oid[2];
  31         int real_oid[CTL_MAXNAME+2];
  32         int error;
  33         size_t oidlen;
  34
  35 #if !TARGET_IPHONE_SIMULATOR
  36         /* Try primary system call first, fall back if not supported */
  37         error = __sysctlbyname(name, strlen(name), oldp, oldlenp, newp, newlen);
  38         if ((error == 0) || (errno != ENOSYS))
  39                 return error;
  40 #endif /* !TARGET_IPHONE_SIMULATOR */
  41
  42         name2oid_oid[0] = 0;    /* This is magic & undocumented! */
  43         name2oid_oid[1] = 3;
  44
  45         oidlen = sizeof(real_oid);
  46         error = __sysctl(name2oid_oid, 2, real_oid, &oidlen, (void *)name,
  47                        strlen(name));
  48         if (error < 0)
  49                 return error;
  50         oidlen /= sizeof (int);
  51         error = __sysctl(real_oid, oidlen, oldp, oldlenp, newp, newlen);
  52         return (error);
  53 }
  54