Work in progres, please take a look and give early feedback if this is the way we want to structure…

lib/io/system_linux.dart

 // Copyright (c) 2014, the Fletch project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 part of system;
 
 const int EPOLLIN       = 0x1;
 const int EPOLLOUT      = 0x4;
 const int EPOLLERR      = 0x8;
 const int EPOLLHUP      = 0x10;
 const int EPOLLRDHUP    = 0x2000;
 const int EPOLLONESHOT  = 0x40000000;
 
 const int EPOLL_CTL_ADD = 1;
 const int EPOLL_CTL_DEL = 2;
 const int EPOLL_CTL_MOD = 3;
 
 class LinuxAddrInfo extends AddrInfo {
   LinuxAddrInfo() : super._();
   LinuxAddrInfo.fromAddress(int address) : super._fromAddress(address);
 
-  Foreign get ai_addr {
+  ForeignMemory get ai_addr {
     int offset = _addrlenOffset + wordSize;
-    return new Foreign.fromAddress(getWord(offset), ai_addrlen);
+    return new ForeignMemory.fromAddress(getWord(offset), ai_addrlen);
   }
 
   get ai_canonname {
     int offset = _addrlenOffset + wordSize * 2;
     return getWord(offset);
   }
 
   AddrInfo get ai_next {
     int offset = _addrlenOffset + wordSize * 3;
     return new LinuxAddrInfo.fromAddress(getWord(offset));
   }
 }
 
-class EpollEvent extends Foreign {
+class EpollEvent extends ForeignMemory {
   // epoll_event is packed on ia32/x64, but not on arm.
   static int eventSize = Foreign.architecture == Foreign.ARM ? 8 : 4;
 
   EpollEvent() : super.allocatedFinalize(eventSize + 8);
 
   int get events => getInt32(0);
   void set events(int value) {
     setInt32(0, value);
   }
 
   int get data => getInt64(eventSize);
   void set data(int value) {
     setInt64(eventSize, value);
   }
 }
 
 class LinuxSystem extends PosixSystem {
-  static final Foreign _epollCtl = Foreign.lookup("epoll_ctl");
-  static final Foreign _lseekLinux = Foreign.lookup("lseek64");
-  static final Foreign _openLinux = Foreign.lookup("open64");
+  static final ForeignFunction _epollCtl =
+      ForeignLibrary.main.lookup("epoll_ctl");
+  static final ForeignFunction _lseekLinux =
+      ForeignLibrary.main.lookup("lseek64");
+  static final ForeignFunction _openLinux =
+      ForeignLibrary.main.lookup("open64");
 
   final EpollEvent _epollEvent = new EpollEvent();
 
   int get FIONREAD => 0x541B;
 
   int get SOL_SOCKET => 1;
 
   int get SO_REUSEADDR => 2;
 
-  Foreign get _lseek => _lseekLinux;
-  Foreign get _open => _openLinux;
+  ForeignFunction get _lseek => _lseekLinux;
+  ForeignFunction get _open => _openLinux;
 
   int addToEventHandler(int fd) {
     _epollEvent.events = 0;
     _epollEvent.data = 0;
     int eh = System.eventHandler;
     return _retry(() => _epollCtl.icall$4(eh, EPOLL_CTL_ADD, fd, _epollEvent));
   }
 
   int removeFromEventHandler(int fd) {
     // TODO(ajohnsen): If we increased the refcount of the port before adding it
     // to the epoll set and we remove it now, we can leak memory.
     int eh = System.eventHandler;
-    return _retry(() => _epollCtl.icall$4(eh, EPOLL_CTL_DEL, fd, Foreign.NULL));
+    return _retry(() => _epollCtl.icall$4(eh, EPOLL_CTL_DEL, fd,
+                                          ForeignPointer.NULL));
   }
 
   int setPortForNextEvent(int fd, Port port, int mask) {
     int events = EPOLLRDHUP | EPOLLHUP | EPOLLONESHOT;
     if ((mask & READ_EVENT) != 0) events |= EPOLLIN;
     if ((mask & WRITE_EVENT) != 0) events |= EPOLLOUT;
     _epollEvent.events = events;
     _epollEvent.data = System._incrementPortRef(port);
     int eh = System.eventHandler;
     return _retry(() => _epollCtl.icall$4(eh, EPOLL_CTL_MOD, fd, _epollEvent));
   }
 }