private int send(FileDescriptor fd, ByteBuffer src, SocketAddress target) throws IOException {
if (src instanceof DirectBuffer) return sendFromNativeBuffer(fd, src, target);
// Substitute a native buffer
int pos = src.position();
int lim = src.limit();
assert (pos <= lim);
int rem = (pos <= lim ? lim - pos : 0);
ByteBuffer bb = Util.getTemporaryDirectBuffer(rem);
try {
bb.put(src);
bb.flip();
// Do not update src until we see how many bytes were written
src.position(pos);
int n = sendFromNativeBuffer(fd, bb, target);
if (n > 0) {
// now update src
src.position(pos + n);
}
return n;
} finally {
Util.releaseTemporaryDirectBuffer(bb);
}
}
public SocketAddress receive(ByteBuffer dst) throws IOException {
if (dst.isReadOnly()) throw new IllegalArgumentException("Read-only buffer");
if (dst == null) throw new NullPointerException();
synchronized (readLock) {
ensureOpen();
// Socket was not bound before attempting receive
if (localAddress() == null) bind(null);
int n = 0;
ByteBuffer bb = null;
try {
begin();
if (!isOpen()) return null;
SecurityManager security = System.getSecurityManager();
readerThread = NativeThread.current();
if (isConnected() || (security == null)) {
do {
n = receive(fd, dst);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
if (n == IOStatus.UNAVAILABLE) return null;
} else {
bb = Util.getTemporaryDirectBuffer(dst.remaining());
for (; ; ) {
do {
n = receive(fd, bb);
} while ((n == IOStatus.INTERRUPTED) && isOpen());
if (n == IOStatus.UNAVAILABLE) return null;
InetSocketAddress isa = (InetSocketAddress) sender;
try {
security.checkAccept(isa.getAddress().getHostAddress(), isa.getPort());
} catch (SecurityException se) {
// Ignore packet
bb.clear();
n = 0;
continue;
}
bb.flip();
dst.put(bb);
break;
}
}
return sender;
} finally {
if (bb != null) Util.releaseTemporaryDirectBuffer(bb);
readerThread = 0;
end((n > 0) || (n == IOStatus.UNAVAILABLE));
assert IOStatus.check(n);
}
}
}
private int receive(FileDescriptor fd, ByteBuffer dst) throws IOException {
int pos = dst.position();
int lim = dst.limit();
assert (pos <= lim);
int rem = (pos <= lim ? lim - pos : 0);
if (dst instanceof DirectBuffer && rem > 0) return receiveIntoNativeBuffer(fd, dst, rem, pos);
// Substitute a native buffer. If the supplied buffer is empty
// we must instead use a nonempty buffer, otherwise the call
// will not block waiting for a datagram on some platforms.
int newSize = Math.max(rem, 1);
ByteBuffer bb = Util.getTemporaryDirectBuffer(newSize);
try {
int n = receiveIntoNativeBuffer(fd, bb, newSize, 0);
bb.flip();
if (n > 0 && rem > 0) dst.put(bb);
return n;
} finally {
Util.releaseTemporaryDirectBuffer(bb);
}
}