import java.io.File ;
import java.io.IOException ;

public class Symlink {
	private static final String[] FAILURES = {null, "get path", "lstat", "new buf", "get buf", "readlink", "size mismatch", "malloc buf", "symlink"} ;
	static {
		System.loadLibrary("symlink") ;
	}
	private Symlink() {}
	public static byte[] readlink(File f) throws IOException {
		String path = f.getAbsolutePath() ;
		byte[][] bufHolder = new byte[1][] ;
		int status = readlink(path, bufHolder) ;
		validateStatus(status) ;
		return bufHolder[0] ;
	}
	private static native int readlink(String path, byte[][] bufHolder) ;
	public static void writelink(File f, byte[] buf) throws IOException {
		String path = f.getCanonicalPath() ;
		int status = symlink(path, buf) ;
		validateStatus(status) ;
	}
	private static native int symlink(String path, byte[] buf) ;
	private static void validateStatus(int status) throws IOException {
		if (status < 0) {
			int failure = (-status) >> 16 ;
			int errno = (-status) & 0xffff ;
			throw new IOException("failure: " + FAILURES[failure] + ", errno: " + Errno.NAMES[errno]) ;
		}
	}
}