directory?

/*
 * call-seq:
 *   File.directory?(file_name)   =>  true or false
 *
 * Returns <code>true</code> if the named file is a directory,
 * <code>false</code> otherwise.
 *
 *    File.directory?(".")
 */

static VALUE
test_d(obj, fname)
    VALUE obj, fname;
{
#ifndef S_ISDIR
#   define S_ISDIR(m) ((m & S_IFMT) == S_IFDIR)
#endif

    struct stat st;

    if (rb_stat(fname, &st) < 0) return Qfalse;
    if (S_ISDIR(st.st_mode)) return Qtrue;
    return Qfalse;
}