/*
 * call-seq:
 *    File.world_readable?(file_name)   => fixnum or nil
 *
 * If <i>file_name</i> is readable by others, returns an integer
 * representing the file permission bits of <i>file_name</i>. Returns
 * <code>nil</code> otherwise. The meaning of the bits is platform
 * dependent; on Unix systems, see <code>stat(2)</code>.
 *     
 *    File.world_readable?("/etc/passwd")           # => 420
 *    m = File.world_readable?("/etc/passwd")
 *    sprintf("%o", m)                              # => "644"
 */

static VALUE
rb_file_world_readable_p(VALUE obj, VALUE fname)
{
#ifdef S_IROTH
    struct stat st;

    if (rb_stat(fname, &st) < 0) return Qnil;
    if ((st.st_mode & (S_IROTH)) == S_IROTH) {
        return UINT2NUM(st.st_mode & (S_IRUGO|S_IWUGO|S_IXUGO));
    }
#endif
    return Qnil;
}