#include <sys/types.h>
#include <unistd.h>
#include <grp.h>

char *prot_uidgid(uid_t uid, gid_t gid, gid_t *gr_list, int len) /*EXTRACT_INCL*/{
  char *p=0;
  if (setgroups(len, gr_list) == -1) p = "groups";
  else if (setgid(gid) == -1) p = "gid";
  else if (setuid(uid) == -1) p = "uid";
  return p;
}