sub is_safe_file {
   my $path = shift;
   stat($path) || return;    # mysteriously vaporized
   my ( $dev, $ino, $mode, $nlink, $uid, $gid ) = stat(_);

   return 0 if $uid != 0 && $uid != $<;
   return 0 if $mode & 022;
   return 1;
} ## end sub is_safe_file