getrawpartition —
get the system “raw” partition
System Utilities Library (libutil, -lutil)
#include <util.h>
int
  
  getrawpartition(void);
getrawpartition() returns the partition number (
  ‘a’ == 0, ‘b’ == 1, ...) of the
  “raw” partition of the system's disks, or -1 in case of an
  error, setting the global errno variable. The possible
  values for errno are the same as in
  sysctl(3). The
  “raw” partition is defined as the partition which provides
  access to the entire disk, regardless of the disk's partition map.
The getrawpartition() function call appeared in
  NetBSD 1.2.