X-Git-Url: http://git.megacz.com/?p=nestedvm.git;a=blobdiff_plain;f=src%2Forg%2Fibex%2Fnestedvm%2FUnixRuntime.java;h=0bc102809b0cb88ac0dda49f5854a35444cb5008;hp=24a7967f0e598f0afc1d8a3cb4bb1fff044caf1b;hb=404ead23c2104bbed240370653a5308849b98905;hpb=034a42fa65955289442614ef9914e5474fac62aa

diff --git a/src/org/ibex/nestedvm/UnixRuntime.java b/src/org/ibex/nestedvm/UnixRuntime.java
index 24a7967..0bc1028 100644
--- a/src/org/ibex/nestedvm/UnixRuntime.java
+++ b/src/org/ibex/nestedvm/UnixRuntime.java
@@ -1,27 +1,31 @@
+// Copyright 2000-2005 the Contributors, as shown in the revision logs.
+// Licensed under the Apache Public Source License 2.0 ("the License").
+// You may not use this file except in compliance with the License.
+
 package org.ibex.nestedvm;
 
 import org.ibex.nestedvm.util.*;
+// HACK: This is ugly, this stuff needs to be in org.ibex.util or something
+import org.ibex.classgen.util.Sort;
 import java.io.*;
 import java.util.*;
+import java.net.*;
+import java.lang.reflect.*; // For lazily linked RuntimeCompiler
 
-// FEATURE: BusyBox's ASH doesn't like \r\n at the end of lines
-// is ash just broken or are many apps like this? if so workaround in nestedvm
-
-// FEATURE: Throw ErrnoException and catch in syscall whereever possible 
-// (only in cases where we've already paid the price for a throw)
+// FEATURE: vfork
 
 public abstract class UnixRuntime extends Runtime implements Cloneable {
     /** The pid of this "process" */
     private int pid;
-    private int ppid;
-    protected int getPid() { return pid; }
+    private UnixRuntime parent;
+    public final int getPid() { return pid; }
     
-    /** processes filesystem */
-    private FS fs;
-    public FS getFS() { return fs; }
-    public void setFS(FS fs) {
-        if(state != STOPPED) throw new IllegalStateException("Can't change fs while process is running");
-        this.fs = fs;
+    private static final GlobalState defaultGS = new GlobalState();
+    private GlobalState gs;
+    public void setGlobalState(GlobalState gs) {
+        if(state != STOPPED) throw new IllegalStateException("can't change GlobalState when running");
+        if(gs == null) throw new NullPointerException("gs is null");
+        this.gs = gs;
     }
     
     /** proceses' current working directory - absolute path WITHOUT leading slash
@@ -30,58 +34,36 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     
     /** The runtime that should be run next when in state == EXECED */
     private UnixRuntime execedRuntime;
+
+    private Object children; // used only for synchronizatin
+    private Vector activeChildren;
+    private Vector exitedChildren;
     
-    /* Static stuff */
-    // FEATURE: Most of this is O(n) or worse - fix it
-    private final Object waitNotification = new Object();
-    private final static int MAX_TASKS = 256;
-    private final static UnixRuntime[] tasks = new UnixRuntime[MAX_TASKS];
-    private static int addTask(UnixRuntime rt) {
-        synchronized(tasks) {
-            for(int i=1;i<MAX_TASKS;i++) {
-                if(tasks[i] == null) {
-                    tasks[i] = rt;
-                    rt.pid = i;
-                    return i;
-                }
-            }
-            return -1;
-        }
-    }
-    private static void removeTask(UnixRuntime rt) {
-        synchronized(tasks) {
-            for(int i=1;i<MAX_TASKS;i++)
-                if(tasks[i] == rt) { tasks[i] = null; break; }
+    protected UnixRuntime(int pageSize, int totalPages) { this(pageSize,totalPages,false); }
+    protected UnixRuntime(int pageSize, int totalPages, boolean exec) {
+        super(pageSize,totalPages,exec);
+                
+        if(!exec) {
+            gs = defaultGS;
+            String userdir = Platform.getProperty("user.dir");
+            cwd = (userdir == null || Platform.getProperty("nestedvm.root") != null) ? null : HostFS.reverseMap(userdir);
+            if(cwd == null) cwd = "/";
+            cwd = cwd.substring(1);
         }
     }
     
-    public UnixRuntime(int pageSize, int totalPages) {
-        super(pageSize,totalPages);
-        
-        FS root = new HostFS();
-        FS dev = new DevFS();
-        MountPointFS mounts = new MountPointFS(root);
-        mounts.add("/dev",dev);
-        fs = mounts;
-        
-        // FEATURE: Do the proper mangling for non-unix hosts
-        String userdir = getSystemProperty("user.dir");
-        cwd = userdir != null && userdir.startsWith("/") && File.separatorChar == '/'  ? userdir.substring(1) : "";
-    }
-    
-    // NOTE: getDisplayName() is a Java2 function
     private static String posixTZ() {
         StringBuffer sb = new StringBuffer();
         TimeZone zone = TimeZone.getDefault();
         int off = zone.getRawOffset() / 1000;
-        sb.append(zone.getDisplayName(false,TimeZone.SHORT));
+        sb.append(Platform.timeZoneGetDisplayName(zone,false,false));
         if(off > 0) sb.append("-");
         else off = -off;
         sb.append(off/3600); off = off%3600;
         if(off > 0) sb.append(":").append(off/60); off=off%60;
         if(off > 0) sb.append(":").append(off);
         if(zone.useDaylightTime())
-            sb.append(zone.getDisplayName(true,TimeZone.SHORT));
+            sb.append(Platform.timeZoneGetDisplayName(zone,true,false));
         return sb.toString();
     }
     
@@ -91,65 +73,141 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         return false;
     }
     
-    protected String[] createEnv(String[] extra) {
-        String[] defaults = new String[5];
+    String[] createEnv(String[] extra) {
+        String[] defaults = new String[7];
         int n=0;
         if(extra == null) extra = new String[0];
-        if(!envHas("USER",extra) && getSystemProperty("user.name") != null)
-            defaults[n++] = "USER=" + getSystemProperty("user.name");
-        if(!envHas("HOME",extra) && getSystemProperty("user.name") != null)
-            defaults[n++] = "HOME=" + getSystemProperty("user.home");
+        String tmp;
+        if(!envHas("USER",extra) && Platform.getProperty("user.name") != null)
+            defaults[n++] = "USER=" + Platform.getProperty("user.name");
+        if(!envHas("HOME",extra) && (tmp=Platform.getProperty("user.home")) != null && (tmp=HostFS.reverseMap(tmp)) != null)
+            defaults[n++] = "HOME=" + tmp;
+        if(!envHas("TMPDIR",extra) && (tmp=Platform.getProperty("java.io.tmpdir")) != null && (tmp=HostFS.reverseMap(tmp)) != null)
+            defaults[n++] = "TMPDIR=" + tmp;
         if(!envHas("SHELL",extra)) defaults[n++] = "SHELL=/bin/sh";
-        if(!envHas("TERM",extra))  defaults[n++] = "TERM=vt100";
+        if(!envHas("TERM",extra) && !win32Hacks)  defaults[n++] = "TERM=vt100";
         if(!envHas("TZ",extra))    defaults[n++] = "TZ=" + posixTZ();
+        if(!envHas("PATH",extra))  defaults[n++] = "PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin";
         String[] env = new String[extra.length+n];
         for(int i=0;i<n;i++) env[i] = defaults[i];
         for(int i=0;i<extra.length;i++) env[n++] = extra[i];
         return env;
     }
     
-    protected void _start() {
-        if(addTask(this) < 0) throw new Error("Task list full");
-    }
+    private static class ProcessTableFullExn extends RuntimeException { }
     
-    protected void _exit() {
-        synchronized(tasks) {
-            if(ppid == 0) removeTask(this);
-            for(int i=0;i<MAX_TASKS;i++) {
-                if(tasks[i] != null && tasks[i].ppid == pid) {
-                    if(tasks[i].state == EXITED) removeTask(tasks[i]);
-                    else tasks[i].ppid = 0;
+    void _started() {
+        UnixRuntime[] tasks = gs.tasks;
+        synchronized(gs) {
+            if(pid != 0) {
+                UnixRuntime prev = tasks[pid];
+                if(prev == null || prev == this || prev.pid != pid || prev.parent != parent)
+                    throw new Error("should never happen");
+                synchronized(parent.children) {
+                    int i = parent.activeChildren.indexOf(prev);
+                    if(i == -1) throw new Error("should never happen");
+                    parent.activeChildren.setElementAt(this,i);
                 }
+            } else {
+                int newpid = -1;
+                int nextPID = gs.nextPID;
+                for(int i=nextPID;i<tasks.length;i++) if(tasks[i] == null) { newpid = i; break; }
+                if(newpid == -1) for(int i=1;i<nextPID;i++) if(tasks[i] == null) { newpid = i; break; }
+                if(newpid == -1) throw new ProcessTableFullExn();
+                pid = newpid;
+                gs.nextPID = newpid + 1;
             }
-            state = EXITED;
-            if(ppid != 0) synchronized(tasks[ppid].waitNotification) { tasks[ppid].waitNotification.notify(); }
+            tasks[pid] = this;
         }
     }
-
-    protected int syscall(int syscall, int a, int b, int c, int d) {
+    
+    int _syscall(int syscall, int a, int b, int c, int d, int e, int f) throws ErrnoException, FaultException {
         switch(syscall) {
             case SYS_kill: return sys_kill(a,b);
             case SYS_fork: return sys_fork();
             case SYS_pipe: return sys_pipe(a);
             case SYS_dup2: return sys_dup2(a,b);
+            case SYS_dup: return sys_dup(a);
             case SYS_waitpid: return sys_waitpid(a,b,c);
             case SYS_stat: return sys_stat(a,b);
+            case SYS_lstat: return sys_lstat(a,b);
             case SYS_mkdir: return sys_mkdir(a,b);
             case SYS_getcwd: return sys_getcwd(a,b);
             case SYS_chdir: return sys_chdir(a);
-            case SYS_execve: return sys_execve(a,b,c);
-
-            default: return super.syscall(syscall,a,b,c,d);
+            case SYS_exec: return sys_exec(a,b,c);
+            case SYS_getdents: return sys_getdents(a,b,c,d);
+            case SYS_unlink: return sys_unlink(a);
+            case SYS_getppid: return sys_getppid();
+            case SYS_socket: return sys_socket(a,b,c);
+            case SYS_connect: return sys_connect(a,b,c);
+            case SYS_resolve_hostname: return sys_resolve_hostname(a,b,c);
+            case SYS_setsockopt: return sys_setsockopt(a,b,c,d,e);
+            case SYS_getsockopt: return sys_getsockopt(a,b,c,d,e);
+            case SYS_bind: return sys_bind(a,b,c);
+            case SYS_listen: return sys_listen(a,b);
+            case SYS_accept: return sys_accept(a,b,c);
+            case SYS_shutdown: return sys_shutdown(a,b);
+            case SYS_sysctl: return sys_sysctl(a,b,c,d,e,f);
+            case SYS_sendto: return sys_sendto(a,b,c,d,e,f);
+            case SYS_recvfrom: return sys_recvfrom(a,b,c,d,e,f);
+            case SYS_select: return sys_select(a,b,c,d,e);
+            case SYS_access: return sys_access(a,b);
+            case SYS_realpath: return sys_realpath(a,b);
+            case SYS_chown: return sys_chown(a,b,c);
+            case SYS_lchown: return sys_chown(a,b,c);
+            case SYS_fchown: return sys_fchown(a,b,c);
+            case SYS_chmod: return sys_chmod(a,b,c);
+            case SYS_fchmod: return sys_fchmod(a,b,c);
+            case SYS_umask: return sys_umask(a);
+            
+            default: return super._syscall(syscall,a,b,c,d,e,f);
         }
     }
     
-    protected FD open(String path, int flags, int mode) throws IOException {
-        return fs.open(normalizePath(path),flags,mode);
+    FD _open(String path, int flags, int mode) throws ErrnoException {
+        return gs.open(this,normalizePath(path),flags,mode);
+    }
+    
+    private int sys_getppid() {
+        return parent == null ? 1 : parent.pid;
+    }
+    
+    private int sys_chown(int fileAddr, int uid, int gid) {
+        return 0;
+    }
+    private int sys_lchown(int fileAddr, int uid, int gid) {
+        return 0;
+    }
+    private int sys_fchown(int fd, int uid, int gid) {
+        return 0;
+    }
+    private int sys_chmod(int fileAddr, int uid, int gid) {
+        return 0;
+    }
+    private int sys_fchmod(int fd, int uid, int gid) {
+        return 0;
+    }
+    private int sys_umask(int mask) {
+        return 0;
+    }
+    
+    private int sys_access(int cstring, int mode) throws ErrnoException, ReadFaultException {
+        // FEATURE: sys_access
+        return gs.stat(this,cstring(cstring)) == null ? -ENOENT : 0;
+    }
+    
+    private int sys_realpath(int inAddr, int outAddr) throws FaultException {
+        String s = normalizePath(cstring(inAddr));
+        byte[] b = getNullTerminatedBytes(s);
+        if(b.length > PATH_MAX) return -ERANGE;
+        copyout(b,outAddr,b.length);
+        return 0;
     }
 
-    // FEATURE: Allow simple, broken signal delivery to other processes 
-    // (check if a signal was delivered before and after syscalls)
-    // FEATURE: Implement raise() in terms of call("raise",...) - kinda cheap, but it keeps the complexity in newlib
+    // FEATURE: Signal handling
+    // check flag only on backwards jumps to basic blocks without compulsatory checks 
+    // (see A Portable Research Framework for the Execution of Java Bytecode - Etienne Gagnon, Chapter 2)
+    
     /** The kill syscall.
        SIGSTOP, SIGTSTO, SIGTTIN, and SIGTTOUT pause the process.
        SIGCONT, SIGCHLD, SIGIO, and SIGWINCH are ignored.
@@ -165,65 +223,105 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             case 18: // SIGTSTP
             case 21: // SIGTTIN
             case 22: // SIGTTOU
-                state = PAUSED;
-                break;
             case 19: // SIGCONT
             case 20: // SIGCHLD
             case 23: // SIGIO
             case 28: // SIGWINCH
                 break;
             default:
-                return syscall(SYS_exit,128+signal,0,0,0);
+                exit(128+signal, true);
         }
         return 0;
     }
 
-    private int sys_waitpid(int pid, int statusAddr, int options) {
+    private int sys_waitpid(int pid, int statusAddr, int options) throws FaultException, ErrnoException {
         final int WNOHANG = 1;
         if((options & ~(WNOHANG)) != 0) return -EINVAL;
-        if(pid !=-1 && (pid <= 0 || pid >= MAX_TASKS)) return -ECHILD;
-        for(;;) {
-            synchronized(tasks) {
-                UnixRuntime task = null;
+        if(pid == 0 || pid < -1) {
+            if(STDERR_DIAG) System.err.println("WARNING: waitpid called with a pid of " + pid);
+            return -ECHILD;
+        }
+        boolean blocking = (options&WNOHANG)==0;
+        
+        if(pid !=-1 && (pid <= 0 || pid >= gs.tasks.length)) return -ECHILD;
+        if(children == null) return blocking ? -ECHILD : 0;
+        
+        UnixRuntime done = null;
+        
+        synchronized(children) {
+            for(;;) {
                 if(pid == -1) {
-                    for(int i=0;i<MAX_TASKS;i++) {
-                        if(tasks[i] != null && tasks[i].ppid == this.pid && tasks[i].state == EXITED) {
-                            task = tasks[i];
-                            break;
-                        }
+                    if(exitedChildren.size() > 0) {
+                        done = (UnixRuntime)exitedChildren.elementAt(exitedChildren.size() - 1);
+                        exitedChildren.removeElementAt(exitedChildren.size() - 1);
                     }
-                } else if(tasks[pid] != null && tasks[pid].ppid == this.pid && tasks[pid].state == EXITED) {
-                    task = tasks[pid];
-                }
-                
-                if(task != null) {
-                    removeTask(task);
-                    try {
-                        if(statusAddr!=0) memWrite(statusAddr,task.exitStatus()<<8);
-                    } catch(FaultException e) {
-                        return -EFAULT;
+                } else if(pid > 0) {
+                    if(pid >= gs.tasks.length) return -ECHILD;
+                    UnixRuntime t = gs.tasks[pid];
+                    if(t.parent != this) return -ECHILD;
+                    if(t.state == EXITED) {
+                        if(!exitedChildren.removeElement(t)) throw new Error("should never happen");
+                        done = t;
                     }
-
-                    return task.pid;
+                } else {
+                    // process group stuff, EINVAL returned above
+                        throw new Error("should never happen");
+                }
+                if(done == null) {
+                    if(!blocking) return 0;
+                    try { children.wait(); } catch(InterruptedException e) {}
+                    //System.err.println("waitpid woke up: " + exitedChildren.size());
+                } else {
+                    gs.tasks[done.pid] = null;
+                    break;
                 }
             }
-            if((options&WNOHANG)!=0) return 0;
-            synchronized(waitNotification) {
-                try { waitNotification.wait(); } catch(InterruptedException e) { /* ignore */ }
+        }
+        if(statusAddr!=0) memWrite(statusAddr,done.exitStatus()<<8);
+        return done.pid;
+    }
+    
+    
+    void _exited() {
+        if(children != null) synchronized(children) {
+            for(Enumeration e = exitedChildren.elements(); e.hasMoreElements(); ) {
+                UnixRuntime child = (UnixRuntime) e.nextElement();
+                gs.tasks[child.pid] = null;
+            }
+            exitedChildren.removeAllElements();
+            for(Enumeration e = activeChildren.elements(); e.hasMoreElements(); ) {
+                UnixRuntime child = (UnixRuntime) e.nextElement();
+                child.parent = null;
+            }
+            activeChildren.removeAllElements();
+        }
+        
+        UnixRuntime _parent = parent;
+        if(_parent == null) {
+            gs.tasks[pid] = null;
+        } else {
+            synchronized(_parent.children) {
+                if(parent == null) {
+                    gs.tasks[pid] = null;
+                } else {
+                    if(!parent.activeChildren.removeElement(this)) throw new Error("should never happen _exited: pid: " + pid);
+                    parent.exitedChildren.addElement(this);
+                    parent.children.notify();
+                }
             }
         }
     }
     
     protected Object clone() throws CloneNotSupportedException {
-    	    UnixRuntime r = (UnixRuntime) super.clone();
-        r.pid = r.ppid = 0;
+        UnixRuntime r = (UnixRuntime) super.clone();
+        r.pid = 0;
+        r.parent = null;
+        r.children = null;
+        r.activeChildren = r.exitedChildren = null;
         return r;
     }
 
     private int sys_fork() {
-        CPUState state = new CPUState();
-        getCPUState(state);
-        int sp = state.r[SP];
         final UnixRuntime r;
         
         try {
@@ -232,39 +330,49 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             e.printStackTrace();
             return -ENOMEM;
         }
+
+        r.parent = this;
+
+        try {
+            r._started();
+        } catch(ProcessTableFullExn e) {
+            return -ENOMEM;
+        }
+
+        //System.err.println("fork " + pid + " -> " + r.pid + " tasks[" + r.pid + "] = " + gd.tasks[r.pid]);
+        if(children == null) {
+            children = new Object();
+            activeChildren = new Vector();
+            exitedChildren = new Vector();
+        }
+        activeChildren.addElement(r);
         
-        int childPID = addTask(r);
-        if(childPID < 0) return -ENOMEM;
-        
-        r.ppid = pid;
-        
+        CPUState state = new CPUState();
+        getCPUState(state);
         state.r[V0] = 0; // return 0 to child
         state.pc += 4; // skip over syscall instruction
         r.setCPUState(state);
         r.state = PAUSED;
         
-        new Thread() {
-            public void run() {
-                try {
-                    while(!r.execute());
-                } catch(Exception e) {
-                    System.err.println("Forked process threw exception: ");
-                    e.printStackTrace();
-                }
-            }
-        }.start();
+        new ForkedProcess(r);
         
-        return childPID;
+        return r.pid;
+    }
+    
+    public static final class ForkedProcess extends Thread {
+        private final UnixRuntime initial;
+        public ForkedProcess(UnixRuntime initial) { this.initial = initial; start(); }
+        public void run() { UnixRuntime.executeAndExec(initial); }
     }
     
     public static int runAndExec(UnixRuntime r, String argv0, String[] rest) { return runAndExec(r,concatArgv(argv0,rest)); }
     public static int runAndExec(UnixRuntime r, String[] argv) { r.start(argv); return executeAndExec(r); }
     
     public static int executeAndExec(UnixRuntime r) {
-    	    for(;;) {
+        for(;;) {
             for(;;) {
                 if(r.execute()) break;
-                System.err.println("WARNING: Pause requested while executing runAndExec()");
+                if(STDERR_DIAG) System.err.println("WARNING: Pause requested while executing runAndExec()");
             }
             if(r.state != EXECED) return r.exitStatus();
             r = r.execedRuntime;
@@ -272,70 +380,167 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
      
     private String[] readStringArray(int addr) throws ReadFaultException {
-    	    int count = 0;
+        int count = 0;
         for(int p=addr;memRead(p) != 0;p+=4) count++;
         String[] a = new String[count];
         for(int i=0,p=addr;i<count;i++,p+=4) a[i] = cstring(memRead(p));
         return a;
     }
     
-    // FEATURE: call the syscall just "exec"
-    private int sys_execve(int cpath, int cargv, int cenvp) {
+    private int sys_exec(int cpath, int cargv, int cenvp) throws ErrnoException, FaultException {
+        return exec(normalizePath(cstring(cpath)),readStringArray(cargv),readStringArray(cenvp));
+    }
+    
+    private final static Method runtimeCompilerCompile;
+    static {
+        Method m;
         try {
-        	    return exec(normalizePath(cstring(cpath)),readStringArray(cargv),readStringArray(cenvp));
-        } catch(FaultException e) {
-            return -EFAULT;
+            m = Class.forName("org.ibex.nestedvm.RuntimeCompiler").getMethod("compile",new Class[]{Seekable.class,String.class,String.class});
+        } catch(NoSuchMethodException e) {
+            m = null;
+        } catch(ClassNotFoundException e) {
+            m = null;
         }
+        runtimeCompilerCompile = m;
     }
-    
-    private int exec(String path, String[] argv, String[] envp) {
-        final UnixRuntime r;
+            
+    public Class runtimeCompile(Seekable s, String sourceName) throws IOException {
+        if(runtimeCompilerCompile == null) {
+            if(STDERR_DIAG) System.err.println("WARNING: Exec attempted but RuntimeCompiler not found!");
+            return null;
+        }
         
-        throw new Error("FIXME exec() not finished");
-        //Class klass = fs.getClass(path);
-        //if(klass != null) return exec(klass,argv,envp);
+        try {
+            return (Class) runtimeCompilerCompile.invoke(null,new Object[]{s,"unixruntime,maxinsnpermethod=256,lessconstants",sourceName});
+        } catch(IllegalAccessException e) {
+            e.printStackTrace();
+            return null;
+        } catch(InvocationTargetException e) {
+            Throwable t = e.getTargetException();
+            if(t instanceof IOException) throw (IOException) t;
+            if(t instanceof RuntimeException) throw (RuntimeException) t;
+            if(t instanceof Error) throw (Error) t;
+            if(STDERR_DIAG) t.printStackTrace();
+            return null;
+        }
+    }
         
+    private int exec(String path, String[] argv, String[] envp) throws ErrnoException {
+        if(argv.length == 0) argv = new String[]{""};
+        // HACK: Hideous hack to make a standalone busybox possible
+        if(path.equals("bin/busybox") && getClass().getName().endsWith("BusyBox"))
+            return execClass(getClass(),argv,envp);
+        
+        // NOTE: For this little hack to work nestedvm.root MUST be "."
         /*try {
-             Seekable s = fs.getSeekable(path);
-             boolean elf = false;
-             boolean script = false;
-             switch(s.read()) {
-                case '\177': elf = s.read() == 'E' && s.read() == 'L' && s.read() == 'F'; break;
-                case '#': script = s.read() == '!';
-            }
-            s.close();
-            if(script) {
-                // FIXME #! support
-                throw new Error("FIXME can't exec scripts yet");
-                // append args, etc
-                // return exec(...)
-            } else if(elf) {
-                klass = fs.(path);
-                if(klass == null) return -ENOEXEC;
-                return exec(klass,argv,envp);
-            } else {
-            	    return -ENOEXEC;
+            System.err.println("Execing normalized path: " + normalizedPath);
+            if(true) return exec(new Interpreter(normalizedPath),argv,envp);
+        } catch(IOException e) { throw new Error(e); }*/
+        
+        FStat fstat = gs.stat(this,path);
+        if(fstat == null) return -ENOENT;
+        GlobalState.CacheEnt ent = (GlobalState.CacheEnt) gs.execCache.get(path);
+        long mtime = fstat.mtime();
+        long size = fstat.size();
+        if(ent != null) {
+            //System.err.println("Found cached entry for " + path);
+            if(ent.time ==mtime && ent.size == size) {
+                if(ent.o instanceof Class)
+                    return execClass((Class) ent.o,argv,envp);
+                if(ent.o instanceof String[]) 
+                    return execScript(path,(String[]) ent.o,argv,envp);
+                throw new Error("should never happen");
             }
-        }*/
-        // FEATURE: Way too much overlap in the handling of ioexeptions everhwere
-        /*catch(ErrnoException e) { return -e.errno; }
-        catch(FileNotFoundException e) {
-            if(e.getMessage() != null && e.getMessage().indexOf("Permission denied") >= 0) return -EACCES;
-            return -ENOENT;
+            //System.err.println("Cache was out of date");
+            gs.execCache.remove(path);
         }
-        catch(IOException e) { return -EIO; }
-        catch(FaultException e) { return -EFAULT; }*/
+        
+        FD fd = gs.open(this,path,RD_ONLY,0);
+        if(fd == null) throw new ErrnoException(ENOENT);
+        Seekable s = fd.seekable();        
+        if(s == null) throw new ErrnoException(EACCES);
+        
+        byte[] buf = new byte[4096];
+        
+        try {
+            int n = s.read(buf,0,buf.length);
+            if(n == -1) throw new ErrnoException(ENOEXEC);
+            
+            switch(buf[0]) {
+                case '\177': // possible ELF
+                    if(n < 4) s.tryReadFully(buf,n,4-n);
+                    if(buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F') return -ENOEXEC;
+                    s.seek(0);
+                    if(STDERR_DIAG) System.err.println("Running RuntimeCompiler for " + path);
+                    Class c = runtimeCompile(s,path);
+                    if(STDERR_DIAG) System.err.println("RuntimeCompiler finished for " + path);
+                    if(c == null) throw new ErrnoException(ENOEXEC);
+                    gs.execCache.put(path,new GlobalState.CacheEnt(mtime,size,c));
+                    return execClass(c,argv,envp);
+                case '#':
+                    if(n == 1) {
+                        int n2 = s.read(buf,1,buf.length-1);
+                        if(n2 == -1) return -ENOEXEC;
+                        n += n2;
+                    }
+                    if(buf[1] != '!') return -ENOEXEC;
+                    int p = 2;
+                    n -= 2;
+                    OUTER: for(;;) {
+                        for(int i=p;i<p+n;i++) if(buf[i] == '\n') { p = i; break OUTER; }
+                            p += n;
+                        if(p == buf.length) break OUTER;
+                        n = s.read(buf,p,buf.length-p);
+                    }
+                    int cmdStart = 2;
+                    for(;cmdStart<p;cmdStart++) if(buf[cmdStart]!=' ') break;
+                    if(cmdStart == p) throw new ErrnoException(ENOEXEC);
+                    int argStart = cmdStart;
+                    for(;argStart<p;argStart++) if(buf[argStart] == ' ') break;
+                    int cmdEnd = argStart;
+                    while(argStart < p && buf[argStart] == ' ') argStart++;
+                    String[] command = new String[] {
+                        new String(buf,cmdStart,cmdEnd-cmdStart),
+                        argStart < p ? new String(buf,argStart,p-argStart) : null
+                    };
+                    gs.execCache.put(path,new GlobalState.CacheEnt(mtime,size,command));
+                    return execScript(path,command,argv,envp);
+                default:
+                    return -ENOEXEC;
+            }
+        } catch(IOException e) {
+            return -EIO;
+        } finally {
+            fd.close();
+        }        
     }
     
-    private int exec(Class c, String[] argv, String[] envp) {
-        UnixRuntime r;
-        
+    public int execScript(String path, String[] command, String[] argv, String[] envp) throws ErrnoException {
+        String[] newArgv = new String[argv.length-1 + (command[1] != null ? 3 : 2)];
+        int p = command[0].lastIndexOf('/');
+        newArgv[0] = p == -1 ? command[0] : command[0].substring(p+1);
+        newArgv[1] = "/" + path;
+        p = 2;
+        if(command[1] != null) newArgv[p++] = command[1];
+        for(int i=1;i<argv.length;i++) newArgv[p++] = argv[i];
+        if(p != newArgv.length) throw new Error("p != newArgv.length");
+        System.err.println("Execing: " + command[0]);
+        for(int i=0;i<newArgv.length;i++) System.err.println("execing [" + i + "] " + newArgv[i]);
+        return exec(command[0],newArgv,envp);
+    }
+    
+    public int execClass(Class c,String[] argv, String[] envp) {
         try {
-        	    r = (UnixRuntime) c.newInstance();
+            UnixRuntime r = (UnixRuntime) c.getDeclaredConstructor(new Class[]{Boolean.TYPE}).newInstance(new Object[]{Boolean.TRUE});
+            return exec(r,argv,envp);
         } catch(Exception e) {
-        	    return -ENOMEM;
+            e.printStackTrace();
+            return -ENOEXEC;
         }
-        
+    }
+    
+    private int exec(UnixRuntime r, String[] argv, String[] envp) {     
+        //System.err.println("Execing " + r);
         for(int i=0;i<OPEN_MAX;i++) if(closeOnExec[i]) closeFD(i);
         r.fds = fds;
         r.closeOnExec = closeOnExec;
@@ -343,33 +548,81 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         fds = null;
         closeOnExec = null;
         
+        r.gs = gs;
+        r.sm = sm;
         r.cwd = cwd;
-        r.fs = fs;
         r.pid = pid;
-        r.ppid = ppid;
+        r.parent = parent;
         r.start(argv,envp);
-        
+                
         state = EXECED;
         execedRuntime = r;
         
         return 0;   
     }
     
-    // FEATURE: Use custom PipeFD - be sure to support PIPE_BUF of data
-    private int sys_pipe(int addr) {
-        PipedOutputStream writerStream = new PipedOutputStream();
-        PipedInputStream readerStream;
-        try {
-             readerStream = new PipedInputStream(writerStream);
-        } catch(IOException e) {
-            return -EIO;
+    static class Pipe {
+        private final byte[] pipebuf = new byte[PIPE_BUF*4];
+        private int readPos;
+        private int writePos;
+        
+        public final FD reader = new Reader();
+        public final FD writer = new Writer();
+        
+        public class Reader extends FD {
+            protected FStat _fstat() { return new SocketFStat(); }
+            public int read(byte[] buf, int off, int len) throws ErrnoException {
+                if(len == 0) return 0;
+                synchronized(Pipe.this) {
+                    while(writePos != -1 && readPos == writePos) {
+                        try { Pipe.this.wait(); } catch(InterruptedException e) { /* ignore */ }
+                    }
+                    if(writePos == -1) return 0; // eof
+                    len = Math.min(len,writePos-readPos);
+                    System.arraycopy(pipebuf,readPos,buf,off,len);
+                    readPos += len;
+                    if(readPos == writePos) Pipe.this.notify();
+                    return len;
+                }
+            }
+            public int flags() { return O_RDONLY; }
+            public void _close() { synchronized(Pipe.this) { readPos = -1; Pipe.this.notify(); } }
         }
-        FD reader = new InputStreamFD(readerStream);
-        FD writer = new OutputStreamFD(writerStream);
-        int fd1 = addFD(reader);
+        
+        public class Writer extends FD {   
+            protected FStat _fstat() { return new SocketFStat(); }
+            public int write(byte[] buf, int off, int len) throws ErrnoException {
+                if(len == 0) return 0;
+                synchronized(Pipe.this) {
+                    if(readPos == -1) throw new ErrnoException(EPIPE);
+                    if(pipebuf.length - writePos < Math.min(len,PIPE_BUF)) {
+                        // not enough space to atomicly write the data
+                        while(readPos != -1 && readPos != writePos) {
+                            try { Pipe.this.wait(); } catch(InterruptedException e) { /* ignore */ }
+                        }
+                        if(readPos == -1) throw new ErrnoException(EPIPE);
+                        readPos = writePos = 0;
+                    }
+                    len = Math.min(len,pipebuf.length - writePos);
+                    System.arraycopy(buf,off,pipebuf,writePos,len);
+                    if(readPos == writePos) Pipe.this.notify();
+                    writePos += len;
+                    return len;
+                }
+            }
+            public int flags() { return O_WRONLY; }
+            public void _close() { synchronized(Pipe.this) { writePos = -1; Pipe.this.notify(); } }
+        }
+    }
+    
+    private int sys_pipe(int addr) {
+        Pipe pipe = new Pipe();
+        
+        int fd1 = addFD(pipe.reader);
         if(fd1 < 0) return -ENFILE;
-        int fd2 = addFD(writer);
+        int fd2 = addFD(pipe.writer);
         if(fd2 < 0) { closeFD(fd1); return -ENFILE; }
+        
         try {
             memWrite(addr,fd1);
             memWrite(addr+4,fd2);
@@ -391,248 +644,789 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         return 0;
     }
     
-    private int sys_stat(int cstring, int addr) {
-        try {
-            String path = normalizePath(cstring(cstring));
-            return stat(fs.stat(path),addr);
-        }
-        catch(ErrnoException e) { return -e.errno; }
-        catch(FileNotFoundException e) {
-            if(e.getMessage() != null && e.getMessage().indexOf("Permission denied") >= 0) return -EACCES;
-            return -ENOENT;
-        }
-        catch(IOException e) { return -EIO; }
-        catch(FaultException e) { return -EFAULT; }
+    private int sys_dup(int oldd) {
+        if(oldd < 0 || oldd >= OPEN_MAX) return -EBADFD;
+        if(fds[oldd] == null) return -EBADFD;
+        FD fd = fds[oldd].dup();
+        int newd = addFD(fd);
+        if(newd < 0) { fd.close(); return -ENFILE; }
+        return newd;
     }
     
+    private int sys_stat(int cstring, int addr) throws FaultException, ErrnoException {
+        FStat s = gs.stat(this,normalizePath(cstring(cstring)));
+        if(s == null) return -ENOENT;
+        return stat(s,addr);
+    }
     
-    private int sys_mkdir(int cstring, int mode) {
-        try {
-            fs.mkdir(normalizePath(cstring(cstring)));
-            return 0;
-        }
-        catch(ErrnoException e) { return -e.errno; }
-        catch(FileNotFoundException e) { return -ENOENT; }
-        catch(IOException e) { return -EIO; }
-        catch(FaultException e) { return -EFAULT; }
+    private int sys_lstat(int cstring, int addr) throws FaultException, ErrnoException {
+        FStat s = gs.lstat(this,normalizePath(cstring(cstring)));
+        if(s == null) return -ENOENT;
+        return stat(s,addr);
+    }
+    
+    private int sys_mkdir(int cstring, int mode) throws FaultException, ErrnoException {
+        gs.mkdir(this,normalizePath(cstring(cstring)),mode);
+        return 0;
     }
    
+    private int sys_unlink(int cstring) throws FaultException, ErrnoException {
+        gs.unlink(this,normalizePath(cstring(cstring)));
+        return 0;
+    }
     
-    private int sys_getcwd(int addr, int size) {
+    private int sys_getcwd(int addr, int size) throws FaultException, ErrnoException {
         byte[] b = getBytes(cwd);
         if(size == 0) return -EINVAL;
         if(size < b.length+2) return -ERANGE;
+        memset(addr,'/',1);
+        copyout(b,addr+1,b.length);
+        memset(addr+b.length+1,0,1);
+        return addr;
+    }
+    
+    private int sys_chdir(int addr) throws ErrnoException, FaultException {
+        String path = normalizePath(cstring(addr));
+        FStat st = gs.stat(this,path);
+        if(st == null) return -ENOENT;
+        if(st.type() != FStat.S_IFDIR) return -ENOTDIR;
+        cwd = path;
+        return 0;
+    }
+    
+    private int sys_getdents(int fdn, int addr, int count, int seekptr) throws FaultException, ErrnoException {
+        count = Math.min(count,MAX_CHUNK);
+        if(fdn < 0 || fdn >= OPEN_MAX) return -EBADFD;
+        if(fds[fdn] == null) return -EBADFD;
+        byte[] buf = byteBuf(count);
+        int n = fds[fdn].getdents(buf,0,count);
+        copyout(buf,addr,n);
+        return n;
+    }
+    
+    static class SocketFD extends FD {
+        public static final int TYPE_STREAM = 0;
+        public static final int TYPE_DGRAM = 1;
+        public static final int LISTEN = 2;
+        public int type() { return flags & 1; }
+        public boolean listen() { return (flags & 2) != 0; }
+        
+        int flags;
+        int options;
+        
+        Socket s;
+        ServerSocket ss;
+        DatagramSocket ds;
+        
+        InetAddress bindAddr;
+        int bindPort = -1;
+        InetAddress connectAddr;
+        int connectPort = -1;
+        
+        DatagramPacket dp;
+        InputStream is;
+        OutputStream os; 
+        
+        private static final byte[] EMPTY = new byte[0];
+        public SocketFD(int type) {
+        	flags = type;
+        	if(type == TYPE_DGRAM)
+        		dp = new DatagramPacket(EMPTY,0);
+        }
+        
+        public void setOptions() {
+            try {
+                if(s != null && type() == TYPE_STREAM && !listen()) {
+                    Platform.socketSetKeepAlive(s,(options & SO_KEEPALIVE) != 0);
+                }
+            } catch(SocketException e) {
+                if(STDERR_DIAG) e.printStackTrace();
+            }
+        }
+        
+        public void _close() {
+            try {
+               if(s != null) s.close();
+               if(ss != null) ss.close();
+               if(ds != null) ds.close();
+            } catch(IOException e) {
+                /* ignore */
+            }
+        }
+        
+        public int read(byte[] a, int off, int length) throws ErrnoException {
+            if(type() == TYPE_DGRAM) return recvfrom(a,off,length,null,null);
+            if(is == null) throw new ErrnoException(EPIPE);
+            try {
+                int n = is.read(a,off,length);
+                return n < 0 ? 0 : n;
+            } catch(IOException e) {
+                throw new ErrnoException(EIO);
+            }
+        }    
+        
+        public int recvfrom(byte[] a, int off, int length, InetAddress[] sockAddr, int[] port) throws ErrnoException {
+        	if(type() == TYPE_STREAM) return read(a,off,length);
+        	
+        	if(off != 0) throw new IllegalArgumentException("off must be 0");
+        	dp.setData(a);
+        	dp.setLength(length);
+        	try {
+        		if(ds == null) ds = new DatagramSocket();
+        		ds.receive(dp);
+        	} catch(IOException e) {
+        		if(STDERR_DIAG) e.printStackTrace();
+        		throw new ErrnoException(EIO);
+        	}
+        	if(sockAddr != null) {
+        		sockAddr[0] = dp.getAddress();
+        		port[0] = dp.getPort();
+        	}
+        	return dp.getLength();
+        }
+        
+        public int write(byte[] a, int off, int length) throws ErrnoException {
+            if(type() == TYPE_DGRAM) return  sendto(a,off,length,null,-1);
+
+            if(os == null) throw new ErrnoException(EPIPE);
+            try {
+                os.write(a,off,length);
+                return length;
+            } catch(IOException e) {
+                throw new ErrnoException(EIO);
+            }
+        }
+        
+        public int sendto(byte[] a, int off, int length, InetAddress destAddr, int destPort) throws ErrnoException {
+        	if(off != 0) throw new IllegalArgumentException("off must be 0");
+        	if(type() == TYPE_STREAM) return write(a,off,length);
+        	
+        	if(destAddr == null) {
+        		destAddr = connectAddr;
+        		destPort = connectPort;
+        		
+        		if(destAddr == null) throw new ErrnoException(ENOTCONN);
+        	}
+        	
+        	dp.setAddress(destAddr);
+        	dp.setPort(destPort);
+        	dp.setData(a);
+        	dp.setLength(length);
+        	
+        	try {
+        		if(ds == null) ds = new DatagramSocket();
+        		ds.send(dp);
+        	} catch(IOException e) {
+        		if(STDERR_DIAG) e.printStackTrace();
+        		if("Network is unreachable".equals(e.getMessage())) throw new ErrnoException(EHOSTUNREACH);
+        		throw new ErrnoException(EIO);
+        	}
+        	return dp.getLength();
+        }
+
+        public int flags() { return O_RDWR; }
+        public FStat _fstat() { return new SocketFStat(); }
+    }
+    
+    private int sys_socket(int domain, int type, int proto) {
+        if(domain != AF_INET || (type != SOCK_STREAM && type != SOCK_DGRAM)) return -EPROTONOSUPPORT;
+        return addFD(new SocketFD(type == SOCK_STREAM ? SocketFD.TYPE_STREAM : SocketFD.TYPE_DGRAM));
+    }
+    
+    private SocketFD getSocketFD(int fdn) throws ErrnoException {
+        if(fdn < 0 || fdn >= OPEN_MAX) throw new ErrnoException(EBADFD);
+        if(fds[fdn] == null) throw new ErrnoException(EBADFD);
+        if(!(fds[fdn] instanceof SocketFD)) throw new ErrnoException(ENOTSOCK);
+        
+        return (SocketFD) fds[fdn];
+    }
+    
+    private int sys_connect(int fdn, int addr, int namelen) throws ErrnoException, FaultException {
+        SocketFD fd = getSocketFD(fdn);
+        
+        if(fd.type() == SocketFD.TYPE_STREAM && (fd.s != null || fd.ss != null)) return -EISCONN;
+        int word1 = memRead(addr);
+        if( ((word1 >>> 16)&0xff) != AF_INET) return -EAFNOSUPPORT;
+        int port = word1 & 0xffff;
+        byte[] ip = new byte[4];
+        copyin(addr+4,ip,4);
+        
+        InetAddress inetAddr;
         try {
-            memset(addr,'/',1);
-            copyout(b,addr+1,b.length);
-            memset(addr+b.length+1,0,1);
-            return addr;
-        } catch(FaultException e) {
-            return -EFAULT;
+            inetAddr = Platform.inetAddressFromBytes(ip);
+        } catch(UnknownHostException e) {
+            return -EADDRNOTAVAIL;
+        }
+        
+        fd.connectAddr = inetAddr;
+        fd.connectPort = port;
+        
+        try {
+            switch(fd.type()) {
+                case SocketFD.TYPE_STREAM: {
+                    Socket s = new Socket(inetAddr,port);
+                    fd.s = s;
+                    fd.setOptions();
+                    fd.is = s.getInputStream();
+                    fd.os = s.getOutputStream();
+                    break;
+                }
+                case SocketFD.TYPE_DGRAM:
+                    break;
+                default:
+                    throw new Error("should never happen");
+            }
+        } catch(IOException e) {
+            return -ECONNREFUSED;
+        }
+        
+        return 0;
+    }
+    
+    private int sys_resolve_hostname(int chostname, int addr, int sizeAddr) throws FaultException {
+        String hostname = cstring(chostname);
+        int size = memRead(sizeAddr);
+        InetAddress[] inetAddrs;
+        try {
+            inetAddrs = InetAddress.getAllByName(hostname);
+        } catch(UnknownHostException e) {
+            return HOST_NOT_FOUND;
+        }
+        int count = min(size/4,inetAddrs.length);
+        for(int i=0;i<count;i++,addr+=4) {
+            byte[] b = inetAddrs[i].getAddress();
+            copyout(b,addr,4);
+        }
+        memWrite(sizeAddr,count*4);
+        return 0;
+    }
+    
+    private int sys_setsockopt(int fdn, int level, int name, int valaddr, int len) throws ReadFaultException, ErrnoException {
+        SocketFD fd = getSocketFD(fdn);
+        switch(level) {
+            case SOL_SOCKET:
+                switch(name) {
+                    case SO_REUSEADDR:
+                    case SO_KEEPALIVE: {
+                        if(len != 4) return -EINVAL;
+                        int val = memRead(valaddr);
+                        if(val != 0) fd.options |= name;
+                        else fd.options &= ~name;
+                        fd.setOptions();
+                        return 0;
+                    }
+                    default:
+                        if(STDERR_DIAG) System.err.println("Unknown setsockopt name passed: " + name);
+                        return -ENOPROTOOPT;
+                }
+            default:
+                if(STDERR_DIAG) System.err.println("Unknown setsockopt leve passed: " + level);
+                return -ENOPROTOOPT;
+        }                   
+    }
+    
+    private int sys_getsockopt(int fdn, int level, int name, int valaddr, int lenaddr) throws ErrnoException, FaultException {
+        SocketFD fd = getSocketFD(fdn);
+        switch(level) {
+            case SOL_SOCKET:
+                switch(name) {
+                    case SO_REUSEADDR:
+                    case SO_KEEPALIVE: {
+                        int len = memRead(lenaddr);
+                        if(len < 4) return -EINVAL;
+                        int val = (fd.options & name) != 0 ? 1 : 0;
+                        memWrite(valaddr,val);
+                        memWrite(lenaddr,4);
+                        return 0;
+                    }
+                    default:
+                        if(STDERR_DIAG) System.err.println("Unknown setsockopt name passed: " + name);
+                        return -ENOPROTOOPT;
+                }
+            default:
+                if(STDERR_DIAG) System.err.println("Unknown setsockopt leve passed: " + level);
+                return -ENOPROTOOPT;
+        } 
+    }
+    
+    private int sys_bind(int fdn, int addr, int namelen) throws FaultException, ErrnoException {
+        SocketFD fd = getSocketFD(fdn);
+        
+        if(fd.type() == SocketFD.TYPE_STREAM && (fd.s != null || fd.ss != null)) return -EISCONN;
+        int word1 = memRead(addr);
+        if( ((word1 >>> 16)&0xff) != AF_INET) return -EAFNOSUPPORT;
+        int port = word1 & 0xffff;
+        InetAddress inetAddr = null;
+        if(memRead(addr+4) != 0) {
+            byte[] ip = new byte[4];
+            copyin(addr+4,ip,4);
+        
+            try {
+                inetAddr = Platform.inetAddressFromBytes(ip);
+            } catch(UnknownHostException e) {
+                return -EADDRNOTAVAIL;
+            }
+        }
+        
+        switch(fd.type()) {
+            case SocketFD.TYPE_STREAM: {
+                fd.bindAddr = inetAddr;
+                fd.bindPort = port;
+                return 0;
+            }
+            case SocketFD.TYPE_DGRAM: {
+                if(fd.ds != null) fd.ds.close();
+                try {
+                    fd.ds = inetAddr != null ? new DatagramSocket(port,inetAddr) : new DatagramSocket(port);
+                } catch(IOException e) {
+                    return -EADDRINUSE;
+                }
+                return 0;
+            }
+            default:
+                throw new Error("should never happen");
         }
     }
     
-    private int sys_chdir(int addr) {
+    private int sys_listen(int fdn, int backlog) throws ErrnoException {
+        SocketFD fd = getSocketFD(fdn);
+        if(fd.type() != SocketFD.TYPE_STREAM) return -EOPNOTSUPP;
+        if(fd.ss != null || fd.s != null) return -EISCONN;
+        if(fd.bindPort < 0) return -EOPNOTSUPP;
+        
         try {
-            String path = normalizePath(cstring(addr));
-            System.err.println("Chdir: " + cstring(addr) + " -> " + path + " pwd: " + cwd);
-            if(fs.stat(path).type() != FStat.S_IFDIR) return -ENOTDIR;
-            cwd = path;
-            System.err.println("Now: [" + cwd + "]");
+            fd.ss = new ServerSocket(fd.bindPort,backlog,fd.bindAddr);
+            fd.flags |= SocketFD.LISTEN;
             return 0;
+        } catch(IOException e) {
+            return -EADDRINUSE;
         }
-        catch(ErrnoException e) { return -e.errno; }
-        catch(FileNotFoundException e) { return -ENOENT; }
-        catch(IOException e) { return -EIO; }
-        catch(FaultException e) { return -EFAULT; }
+        
     }
+    
+    private int sys_accept(int fdn, int addr, int lenaddr) throws ErrnoException, FaultException {
+        SocketFD fd = getSocketFD(fdn);
+        if(fd.type() != SocketFD.TYPE_STREAM) return -EOPNOTSUPP;
+        if(!fd.listen()) return -EOPNOTSUPP;
 
-    public void chdir(String dir) throws FileNotFoundException {
-        if(state != STOPPED) throw new IllegalStateException("Can't chdir while process is running");
+        int size = memRead(lenaddr);
+        
+        ServerSocket s = fd.ss;
+        Socket client;
         try {
-            dir = normalizePath(dir);
-            if(fs.stat(dir).type() != FStat.S_IFDIR) throw new FileNotFoundException();
+            client = s.accept();
         } catch(IOException e) {
-            throw new FileNotFoundException();
+            return -EIO;
+        }
+        
+        if(size >= 8) {
+            memWrite(addr,(6 << 24) | (AF_INET << 16) | client.getPort());
+            byte[] b = client.getInetAddress().getAddress();
+            copyout(b,addr+4,4);
+            memWrite(lenaddr,8);
         }
-        cwd = dir;
+        
+        SocketFD clientFD = new SocketFD(SocketFD.TYPE_STREAM);
+        clientFD.s = client;
+        try {
+            clientFD.is = client.getInputStream();
+            clientFD.os = client.getOutputStream();
+        } catch(IOException e) {
+            return -EIO;
+        }
+        int n = addFD(clientFD);
+        if(n == -1) { clientFD.close(); return -ENFILE; }
+        return n;
     }
+    
+    private int sys_shutdown(int fdn, int how) throws ErrnoException {
+        SocketFD fd = getSocketFD(fdn);
+        if(fd.type() != SocketFD.TYPE_STREAM || fd.listen()) return -EOPNOTSUPP;
+        if(fd.s == null) return -ENOTCONN;
         
+        Socket s = fd.s;
+        
+        try {
+            if(how == SHUT_RD || how == SHUT_RDWR) Platform.socketHalfClose(s,false);
+            if(how == SHUT_WR || how == SHUT_RDWR) Platform.socketHalfClose(s,true);
+        } catch(IOException e) {
+            return -EIO;
+        }
+        
+        return 0;
+    }
+    
+    private int sys_sendto(int fdn, int addr, int count, int flags, int destAddr, int socklen) throws ErrnoException,ReadFaultException {
+    	SocketFD fd = getSocketFD(fdn);
+    	if(flags != 0) throw new ErrnoException(EINVAL);
+    	
+    	int word1 = memRead(destAddr);
+    	if( ((word1 >>> 16)&0xff) != AF_INET) return -EAFNOSUPPORT;
+    	int port = word1 & 0xffff;
+    	InetAddress inetAddr;
+		byte[] ip = new byte[4];
+		copyin(destAddr+4,ip,4);
+		try {
+			inetAddr = Platform.inetAddressFromBytes(ip);
+		} catch(UnknownHostException e) {
+			return -EADDRNOTAVAIL;
+		}
+    	
+    	count = Math.min(count,MAX_CHUNK);
+    	byte[] buf = byteBuf(count);
+    	copyin(addr,buf,count);
+    	try {
+    		return fd.sendto(buf,0,count,inetAddr,port);
+    	} catch(ErrnoException e) {
+    		if(e.errno == EPIPE) exit(128+13,true);
+    		throw e;
+    	}
+    }
+    
+    private int sys_recvfrom(int fdn, int addr, int count, int flags, int sourceAddr, int socklenAddr) throws ErrnoException, FaultException {
+    	SocketFD fd = getSocketFD(fdn);
+    	if(flags != 0) throw new ErrnoException(EINVAL);
+    	
+    	InetAddress[] inetAddr = sourceAddr == 0 ? null : new InetAddress[1];
+    	int[] port = sourceAddr == 0 ? null : new int[1];
+    	
+    	count = Math.min(count,MAX_CHUNK);
+    	byte[] buf = byteBuf(count);
+    	int n = fd.recvfrom(buf,0,count,inetAddr,port);
+    	copyout(buf,addr,n);
+    	
+    	if(sourceAddr != 0) {
+    		memWrite(sourceAddr,(AF_INET << 16) | port[0]);
+    		byte[] ip = inetAddr[0].getAddress();
+    		copyout(ip,sourceAddr+4,4);
+    	}
+    	
+    	return n;
+    }
+    
+    private int sys_select(int n, int readFDs, int writeFDs, int exceptFDs, int timevalAddr) throws ReadFaultException, ErrnoException {
+    	return -ENOSYS;
+    }
+    
+    private static String hostName() {
+        try {
+            return InetAddress.getLocalHost().getHostName();
+        } catch(UnknownHostException e) {
+            return "darkstar";
+        }
+    }
+    
+    private int sys_sysctl(int nameaddr, int namelen, int oldp, int oldlenaddr, int newp, int newlen) throws FaultException {
+        if(newp != 0) return -EPERM;
+        if(namelen == 0) return -ENOENT;
+        if(oldp == 0) return 0;
+        
+        Object o = null;
+        switch(memRead(nameaddr)) {
+            case CTL_KERN:
+                if(namelen != 2) break;
+                switch(memRead(nameaddr+4)) {
+                    case KERN_OSTYPE: o = "NestedVM"; break;
+                    case KERN_HOSTNAME: o = hostName(); break;
+                    case KERN_OSRELEASE: o = VERSION; break;
+                    case KERN_VERSION: o = "NestedVM Kernel Version " + VERSION; break;
+                }
+                break;
+            case CTL_HW:
+                if(namelen != 2) break;
+                switch(memRead(nameaddr+4)) {
+                    case HW_MACHINE: o = "NestedVM Virtual Machine"; break;
+                }
+                break;
+        }
+        if(o == null) return -ENOENT;
+        int len = memRead(oldlenaddr);
+        if(o instanceof String) {
+            byte[] b = getNullTerminatedBytes((String)o);
+            if(len < b.length) return -ENOMEM;
+            len = b.length;
+            copyout(b,oldp,len);
+            memWrite(oldlenaddr,len);
+        } else if(o instanceof Integer) {
+            if(len < 4) return -ENOMEM;
+            memWrite(oldp,((Integer)o).intValue());
+        } else {
+            throw new Error("should never happen");
+        }
+        return 0;
+    }
+    
+    public static final class GlobalState {
+        Hashtable execCache = new Hashtable();
+        
+        final UnixRuntime[] tasks;
+        int nextPID = 1;
+        
+        private MP[] mps = new MP[0];
+        private FS root;
+        
+        public GlobalState() { this(255); }
+        public GlobalState(int maxProcs) { this(maxProcs,true); }
+        public GlobalState(int maxProcs, boolean defaultMounts) {
+            tasks = new UnixRuntime[maxProcs+1];
+            if(defaultMounts) {
+                addMount("/",new HostFS());
+                addMount("/dev",new DevFS());
+                addMount("/resource",new ResourceFS());
+            }
+        }
+        
+        static class MP implements Sort.Comparable {
+            public MP(String path, FS fs) { this.path = path; this.fs = fs; }
+            public String path;
+            public FS fs;
+            public int compareTo(Object o) {
+                if(!(o instanceof MP)) return 1;
+                return -path.compareTo(((MP)o).path);
+            }
+        }
+        
+        public synchronized FS getMount(String path) {
+            if(!path.startsWith("/")) throw new IllegalArgumentException("Mount point doesn't start with a /");
+            if(path.equals("/")) return root;
+            path  = path.substring(1);
+            for(int i=0;i<mps.length;i++)
+                if(mps[i].path.equals(path)) return mps[i].fs;
+            return null;
+        }
+        
+        public synchronized void addMount(String path, FS fs) {
+            if(getMount(path) != null) throw new IllegalArgumentException("mount point already exists");
+            if(!path.startsWith("/")) throw new IllegalArgumentException("Mount point doesn't start with a /");
+            
+            if(fs.owner != null) fs.owner.removeMount(fs);
+            fs.owner = this;
+            
+            if(path.equals("/")) { root = fs; fs.devno = 1; return; }
+            path = path.substring(1);
+            int oldLength = mps.length;
+            MP[] newMPS = new MP[oldLength + 1];
+            if(oldLength != 0) System.arraycopy(mps,0,newMPS,0,oldLength);
+            newMPS[oldLength] = new MP(path,fs);
+            Sort.sort(newMPS);
+            mps = newMPS;
+            int highdevno = 0;
+            for(int i=0;i<mps.length;i++) highdevno = max(highdevno,mps[i].fs.devno);
+            fs.devno = highdevno + 2;
+        }
+        
+        public synchronized void removeMount(FS fs) {
+            for(int i=0;i<mps.length;i++) if(mps[i].fs == fs) { removeMount(i); return; }
+            throw new IllegalArgumentException("mount point doesn't exist");
+        }
+        
+        public synchronized void removeMount(String path) {
+            if(!path.startsWith("/")) throw new IllegalArgumentException("Mount point doesn't start with a /");
+            if(path.equals("/")) {
+                removeMount(-1);
+            } else {
+                path = path.substring(1);
+                int p;
+                for(p=0;p<mps.length;p++) if(mps[p].path.equals(path)) break;
+                if(p == mps.length) throw new IllegalArgumentException("mount point doesn't exist");
+                removeMount(p);
+            }
+        }
+        
+        private void removeMount(int index) {
+            if(index == -1) { root.owner = null; root = null; return; }
+            MP[] newMPS = new MP[mps.length - 1];
+            System.arraycopy(mps,0,newMPS,0,index);
+            System.arraycopy(mps,0,newMPS,index,mps.length-index-1);
+            mps = newMPS;
+        }
+        
+        private Object fsop(int op, UnixRuntime r, String normalizedPath, int arg1, int arg2) throws ErrnoException {
+            int pl = normalizedPath.length();
+            if(pl != 0) {
+                MP[] list;
+                synchronized(this) { list = mps; }
+                for(int i=0;i<list.length;i++) {
+                    MP mp = list[i];
+                    int mpl = mp.path.length();
+                    if(normalizedPath.startsWith(mp.path) && (pl == mpl || normalizedPath.charAt(mpl) == '/'))
+                        return mp.fs.dispatch(op,r,pl == mpl ? "" : normalizedPath.substring(mpl+1),arg1,arg2);
+                }
+            }
+            return root.dispatch(op,r,normalizedPath,arg1,arg2);
+        }
+        
+        public final FD open(UnixRuntime r, String path, int flags, int mode) throws ErrnoException { return (FD) fsop(FS.OPEN,r,path,flags,mode); }
+        public final FStat stat(UnixRuntime r, String path) throws ErrnoException { return (FStat) fsop(FS.STAT,r,path,0,0); }
+        public final FStat lstat(UnixRuntime r, String path) throws ErrnoException { return (FStat) fsop(FS.LSTAT,r,path,0,0); }
+        public final void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException { fsop(FS.MKDIR,r,path,mode,0); }
+        public final void unlink(UnixRuntime r, String path) throws ErrnoException { fsop(FS.UNLINK,r,path,0,0); }
+        
+        private static class CacheEnt {
+            public final long time;
+            public final long size;
+            public final Object o;
+            public CacheEnt(long time, long size, Object o) { this.time = time; this.size = size; this.o = o; }
+        }
+    }
+    
     public abstract static class FS {
-        protected FD _open(String path, int flags, int mode) throws IOException { return null; }
-        protected FStat _stat(String path) throws IOException { return null; }
-        protected void _mkdir(String path) throws IOException { throw new ErrnoException(EROFS); }
-        
-        protected static final int OPEN = 1;
-        protected static final int STAT = 2;
-        protected static final int MKDIR = 3;
-        
-        protected Object op(int op, String path, int arg1, int arg2) throws IOException {
-        		switch(op) {
-        			case OPEN: return _open(path,arg1,arg2);
-        			case STAT: return _stat(path);
-        			case MKDIR: _mkdir(path); return null;
-        			default: throw new IllegalArgumentException("Unknown FS OP");
-        		}
-        }
-        
-        public final FD open(String path, int flags, int mode) throws IOException { return (FD) op(OPEN,path,flags,mode); }
-        public final FStat stat(String path) throws IOException { return (FStat) op(STAT,path,0,0); }
-        public final void mkdir(String path) throws IOException { op(MKDIR,path,0,0); }
-        
-		
-		// FEATURE: inode stuff
-        // FEATURE: Implement whatever is needed to get newlib's opendir and friends to work - that patch is a pain
-        protected static FD directoryFD(String[] files, int hashCode) throws IOException {
-            ByteArrayOutputStream bos = new ByteArrayOutputStream();
-            DataOutputStream dos = new DataOutputStream(bos);
-            for(int i=0;i<files.length;i++) {
-                byte[] b = getBytes(files[i]);
-                int inode = (files[i].hashCode() ^ hashCode) & 0xfffff;
-                dos.writeInt(inode);
-                dos.writeInt(b.length);
-                dos.write(b,0,b.length);
-            }
-            final byte[] data = bos.toByteArray();
-            return new SeekableFD(new Seekable.ByteArray(data,false),RD_ONLY) {
-                protected FStat _fstat() { return  new FStat() {
-                    public int length() { return data.length; }
-                    public int type() { return S_IFDIR; }
-                }; }
-            };
+        static final int OPEN = 1;
+        static final int STAT = 2;
+        static final int LSTAT = 3;
+        static final int MKDIR = 4;
+        static final int UNLINK = 5;
+        
+        GlobalState owner;
+        int devno;
+        
+        Object dispatch(int op, UnixRuntime r, String path, int arg1, int arg2) throws ErrnoException {
+            switch(op) {
+                case OPEN: return open(r,path,arg1,arg2);
+                case STAT: return stat(r,path);
+                case LSTAT: return lstat(r,path);
+                case MKDIR: mkdir(r,path,arg1); return null;
+                case UNLINK: unlink(r,path); return null;
+                default: throw new Error("should never happen");
+            }
         }
+        
+        public FStat lstat(UnixRuntime r, String path) throws ErrnoException { return stat(r,path); }
+
+        // If this returns null it'll be truned into an ENOENT
+        public abstract FD open(UnixRuntime r, String path, int flags, int mode) throws ErrnoException;
+        // If this returns null it'll be turned into an ENOENT
+        public abstract FStat stat(UnixRuntime r, String path) throws ErrnoException;
+        public abstract void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException;
+        public abstract void unlink(UnixRuntime r, String path) throws ErrnoException;
     }
         
+    // chroot support should go in here if it is ever implemented chroot support in here
     private String normalizePath(String path) {
         boolean absolute = path.startsWith("/");
         int cwdl = cwd.length();
+        
         // NOTE: This isn't just a fast path, it handles cases the code below doesn't
         if(!path.startsWith(".") && path.indexOf("./") == -1 && path.indexOf("//") == -1 && !path.endsWith("."))
             return absolute ? path.substring(1) : cwdl == 0 ? path : path.length() == 0 ? cwd : cwd + "/" + path;
         
         char[] in = new char[path.length()+1];
         char[] out = new char[in.length + (absolute ? -1 : cwd.length())];
+        path.getChars(0,path.length(),in,0);
         int inp=0, outp=0;
         
         if(absolute) {
             do { inp++; } while(in[inp] == '/');
         } else if(cwdl != 0) {
-            	cwd.getChars(0,cwdl,out,0);
-            	outp = cwdl;
+            cwd.getChars(0,cwdl,out,0);
+            outp = cwdl;
         }
-            
-        path.getChars(0,path.length(),in,0);
+
         while(in[inp] != 0) {
             if(inp != 0) {
-            	    if(in[inp] != '/') { out[outp++] = in[inp++]; continue; }
-            	    while(in[inp] == '/') inp++;
+                while(in[inp] != 0 && in[inp] != '/') { out[outp++] = in[inp++]; }
+                if(in[inp] == '\0') break;
+                while(in[inp] == '/') inp++;
             }
-            if(in[inp] == '\0') continue;
+            
+            // Just read a /
+            if(in[inp] == '\0') break;
             if(in[inp] != '.') { out[outp++] = '/'; out[outp++] = in[inp++]; continue; }
+            // Just read a /.
             if(in[inp+1] == '\0' || in[inp+1] == '/') { inp++; continue; }
             if(in[inp+1] == '.' && (in[inp+2] == '\0' || in[inp+2] == '/')) { // ..
+                // Just read a /..{$,/}
                 inp += 2;
                 if(outp > 0) outp--;
                 while(outp > 0 && out[outp] != '/') outp--;
-                System.err.println("After ..: " + new String(out,0,outp));
+                //System.err.println("After ..: " + new String(out,0,outp));
                 continue;
             }
+            // Just read a /.[^.] or /..[^/$]
             inp++;
             out[outp++] = '/';
             out[outp++] = '.';
         }
         if(outp > 0 && out[outp-1] == '/') outp--;
         //System.err.println("normalize: " + path + " -> " + new String(out,0,outp) + " (cwd: " + cwd + ")");
-        return new String(out,0,outp);
+        int outStart = out[0] == '/' ? 1 : 0;
+        return new String(out,outStart,outp - outStart);
     }
     
-    public static class MountPointFS extends FS {
-        private static class MP {
-            public MP(String path, FS fs) { this.path = path; this.fs = fs; }
-            public String path;
-            public FS fs;
-            public int compareTo(Object o) {
-                if(!(o instanceof MP)) return 1;
-                return -path.compareTo(((MP)o).path);
-            }
-        }
-        private final MP[][] mps = new MP[128][];
-        private final FS root;
-        public MountPointFS(FS root) { this.root = root; }
-        
-        private static String fixup(String path) {
-            if(!path.startsWith("/")) throw new IllegalArgumentException("Mount point doesn't start with a /");
-            path = path.substring(1);
-            if(path.length() == 0) throw new IllegalArgumentException("Zero length mount point path");
-            return path;
-        }
-        public synchronized FS get(String path) {
-            path = fixup(path);
-            int f = path.charAt(0) & 0x7f;
-            for(int i=0;mps[f] != null && i < mps[f].length;i++)
-                if(mps[f][i].path.equals(path)) return mps[f][i].fs;
-            return null;
-        }
-        
-        public synchronized void add(String path, FS fs) {
-            if(get(path) != null) throw new IllegalArgumentException("mount point already exists");
-            path = fixup(path);
-            int f = path.charAt(0) & 0x7f;
-            int oldLength = mps[f] == null ? 0 : mps[f].length;
-            MP[] newList = new MP[oldLength + 1];
-            if(oldLength != 0) System.arraycopy(mps[f],0,newList,0,oldLength);
-            newList[oldLength] = new MP(path,fs);
-            Arrays.sort(newList);
-            mps[f] = newList;
-        }
-        
-        public synchronized void remove(String path) {
-            path = fixup(path);
-            if(get(path) == null) throw new IllegalArgumentException("mount point doesn't exist");
-            int f = path.charAt(0) & 0x7f;
-            MP[] oldList = mps[f];
-            MP[] newList = new MP[oldList.length - 1];
-            int p = 0;
-            for(p=0;p<oldList.length;p++) if(oldList[p].path.equals(path)) break;
-            if(p == oldList.length) throw new Error("should never happen");
-            System.arraycopy(oldList,0,newList,0,p);
-            System.arraycopy(oldList,0,newList,p,oldList.length-p-1);
-            mps[f] = newList;
-        }
-        
-        protected Object op(int op, String path, int arg1, int arg2) throws IOException {
-            int pl = path.length();
-            if(pl != 0) {
-            	    MP[] list = mps[path.charAt(0) & 0x7f];
-            	    if(list != null) for(int i=0;i<list.length;i++) {
-            	    	    	MP mp = list[i];
-            	    	    	int mpl = mp.path.length();
-            	    	    	if(pl == mpl || (pl < mpl && path.charAt(mpl) == '/'))
-            	    	    	return mp.fs.op(op,pl == mpl ? "" : path.substring(mpl+1),arg1,arg2);
-                 }
+    FStat hostFStat(final File f, Object data) {
+        boolean e = false;
+        try {
+            FileInputStream fis = new FileInputStream(f);
+            switch(fis.read()) {
+                case '\177': e = fis.read() == 'E' && fis.read() == 'L' && fis.read() == 'F'; break;
+                case '#': e = fis.read() == '!';
             }
-            return root.op(op,path,arg1,arg2);
-        }
+            fis.close();
+        } catch(IOException e2) { } 
+        HostFS fs = (HostFS) data;
+        final int inode = fs.inodes.get(f.getAbsolutePath());
+        final int devno = fs.devno;
+        return new HostFStat(f,e) {
+            public int inode() { return inode; }
+            public int dev() { return devno; }
+        };
     }
-        
+
+    FD hostFSDirFD(File f, Object _fs) {
+        HostFS fs = (HostFS) _fs;
+        return fs.new HostDirFD(f);
+    }
+    
     public static class HostFS extends FS {
+        InodeCache inodes = new InodeCache(4000);
         protected File root;
         public File getRoot() { return root; }
         
-        private static File hostRootDir() {
-            String cwd = getSystemProperty("user.dir");
+        static File hostRootDir() {
+            if(Platform.getProperty("nestedvm.root") != null) {
+                File f = new File(Platform.getProperty("nestedvm.root"));
+                if(f.isDirectory()) return f;
+                // fall through to case below
+            }
+            String cwd = Platform.getProperty("user.dir");
             File f = new File(cwd != null ? cwd : ".");
+            if(!f.exists()) throw new Error("Couldn't get File for cwd");
             f = new File(f.getAbsolutePath());
             while(f.getParent() != null) f = new File(f.getParent());
+            // This works around a bug in some versions of ClassPath
+            if(f.getPath().length() == 0) f = new File("/");
             return f;
         }
         
-        File hostFile(String path) {
+        static String reverseMap(String f) {
+            if(f.startsWith("/") && File.separatorChar == '/') return f;
+                
+            Vector vec = new Vector();
+            File root = HostFS.hostRootDir();
+            String s = new File(f).getAbsolutePath();
+            File d = new File(s);
+            System.err.println(s);
+            System.err.println(d);
+            while(!d.equals(root)) {
+                vec.addElement(d.getName());
+                if((s = d.getParent()) == null) break;
+                d = new File(s);
+            }
+            String ret = null;
+            if(s != null) {
+                ret="/";
+                for(int i=vec.size()-1;i>=0;i--) ret += (String) vec.elementAt(i) + (i==0?"":"/");
+            }
+            System.err.println("reverseMap: " + f + " => " + ret);
+            return ret;
+        }
+        
+        private File hostFile(String path) {
             char sep = File.separatorChar;
             if(sep != '/') {
                 char buf[] = path.toCharArray();
                 for(int i=0;i<buf.length;i++) {
-                	    char c = buf[i];
+                    char c = buf[i];
                     if(c == '/') buf[i] = sep;
                     else if(c == sep) buf[i] = '/';
                 }
@@ -646,119 +1440,287 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public HostFS(File root) { this.root = root; }
         
         
-        // FEATURE: This shares a lot with Runtime.open
-        // NOTE: createNewFile is a Java2 function
-        public FD _open(String path, int flags, int mode) throws IOException {
+        public FD open(UnixRuntime r, String path, int flags, int mode) throws ErrnoException {
             final File f = hostFile(path);
-            if(f.isDirectory()) {
-                if((flags&3)!=RD_ONLY) throw new ErrnoException(EACCES);
-                return directoryFD(f.list(),path.hashCode());
-            }
-            if((flags & (O_EXCL|O_CREAT)) == (O_EXCL|O_CREAT))
-                if(!f.createNewFile()) throw new ErrnoException(EEXIST);
-            if((flags&O_CREAT) == 0 && !f.exists())
-                return null;
-            final Seekable.File sf = new Seekable.File(f,(flags&3)!=RD_ONLY);
-            if((flags&O_TRUNC)!=0) sf.setLength(0);
-            return new SeekableFD(sf,mode) {
-                protected FStat _fstat() { return new HostFStat(f) {
-                    public int size() {
-                        try { return sf.length(); } catch(IOException e) { return 0; }
-                    }
-                };}
-            };
+            return r.hostFSOpen(f,flags,mode,this);
         }
         
-        public FStat _stat(String path) throws FileNotFoundException {
+        public void unlink(UnixRuntime r, String path) throws ErrnoException {
             File f = hostFile(path);
-            if(!f.exists()) throw new FileNotFoundException();
-            return new HostFStat(f);
+            if(r.sm != null && !r.sm.allowUnlink(f)) throw new ErrnoException(EPERM);
+            if(!f.exists()) throw new ErrnoException(ENOENT);
+            if(!f.delete()) throw new ErrnoException(EPERM);
         }
         
-        public void _mkdir(String path) throws IOException {
+        public FStat stat(UnixRuntime r, String path) throws ErrnoException {
             File f = hostFile(path);
+            if(r.sm != null && !r.sm.allowStat(f)) throw new ErrnoException(EACCES);
+            if(!f.exists()) return null;
+            return r.hostFStat(f,this);
+        }
+        
+        public void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException {
+            File f = hostFile(path);
+            if(r.sm != null && !r.sm.allowWrite(f)) throw new ErrnoException(EACCES);
             if(f.exists() && f.isDirectory()) throw new ErrnoException(EEXIST);
             if(f.exists()) throw new ErrnoException(ENOTDIR);
-            File parent = f.getParentFile();
+            File parent = getParentFile(f);
             if(parent!=null && (!parent.exists() || !parent.isDirectory())) throw new ErrnoException(ENOTDIR);
             if(!f.mkdir()) throw new ErrnoException(EIO);            
         }
+        
+        private static File getParentFile(File f) {
+            String p = f.getParent();
+            return p == null ? null : new File(p);
+        }
+        
+        public class HostDirFD extends DirFD {
+            private final File f;
+            private final File[] children;
+            public HostDirFD(File f) {
+                this.f = f;
+                String[] l = f.list();
+                children = new File[l.length];
+                for(int i=0;i<l.length;i++) children[i] = new File(f,l[i]);
+            }
+            public int size() { return children.length; }
+            public String name(int n) { return children[n].getName(); }
+            public int inode(int n) { return inodes.get(children[n].getAbsolutePath()); }
+            public int parentInode() {
+                File parent = getParentFile(f);
+                // HACK: myInode() isn't really correct  if we're not the root
+                return parent == null ? myInode() : inodes.get(parent.getAbsolutePath());
+            }
+            public int myInode() { return inodes.get(f.getAbsolutePath()); }
+            public int myDev() { return devno; } 
+        }
+    }
+    
+    private static void putInt(byte[] buf, int off, int n) {
+        buf[off+0] = (byte)((n>>>24)&0xff);
+        buf[off+1] = (byte)((n>>>16)&0xff);
+        buf[off+2] = (byte)((n>>> 8)&0xff);
+        buf[off+3] = (byte)((n>>> 0)&0xff);
+    }
+    
+    public static abstract class DirFD extends FD {
+        private int pos = -2;
+        
+        protected abstract int size();
+        protected abstract String name(int n);
+        protected abstract int inode(int n);
+        protected abstract int myDev();
+        protected abstract int parentInode();
+        protected abstract int myInode();
+        public int flags() { return O_RDONLY; }
+
+        public int getdents(byte[] buf, int off, int len) {
+            int ooff = off;
+            int ino;
+            int reclen;
+            OUTER: for(;len > 0 && pos < size();pos++){
+                switch(pos) {
+                    case -2:
+                    case -1:
+                        ino = pos == -1 ? parentInode() : myInode();
+                        if(ino == -1) continue;
+                        reclen = 9 + (pos == -1 ? 2 : 1);
+                        if(reclen > len) break OUTER;
+                        buf[off+8] = '.';
+                        if(pos == -1) buf[off+9] = '.';
+                        break;
+                    default: {
+                        String f = name(pos);
+                        byte[] fb = getBytes(f);
+                        reclen = fb.length + 9;
+                        if(reclen > len) break OUTER;
+                        ino = inode(pos);
+                        System.arraycopy(fb,0,buf,off+8,fb.length);
+                    }
+                }
+                buf[off+reclen-1] = 0; // null terminate
+                reclen = (reclen + 3) & ~3; // add padding
+                putInt(buf,off,reclen);
+                putInt(buf,off+4,ino);
+                off += reclen;
+                len -= reclen;    
+            }
+            return off-ooff;
+        }
+        
+        protected FStat _fstat() {
+            return new FStat() { 
+                public int type() { return S_IFDIR; }
+                public int inode() { return myInode(); }
+                public int dev() { return myDev(); }
+            };
+        }
     }
         
-    private static class DevFStat extends FStat {
-        public int dev() { return 1; }
-        public int mode() { return 0666; }
-        public int type() { return S_IFCHR; }
-        public int nlink() { return 1; }
-    }
-    private static FD devZeroFD = new FD() {
-        public boolean readable() { return true; }
-        public boolean writable() { return true; }
-        public int read(byte[] a, int off, int length) { Arrays.fill(a,off,off+length,(byte)0); return length; }
-        public int write(byte[] a, int off, int length) { return length; }
-        public int seek(int n, int whence) { return 0; }
-        public FStat _fstat() { return new DevFStat(); }
-    };
-    private static FD devNullFD = new FD() {
-        public boolean readable() { return true; }
-        public boolean writable() { return true; }
-        public int read(byte[] a, int off, int length) { return 0; }
-        public int write(byte[] a, int off, int length) { return length; }
-        public int seek(int n, int whence) { return 0; }
-        public FStat _fstat() { return new DevFStat(); }
-    };    
-    
-    // FIXME: Support /dev/fd (need to have syscalls pass along Runtime instance)
     public static class DevFS extends FS {
-        public FD _open(String path, int mode, int flags) throws IOException {
+        private static final int ROOT_INODE = 1;
+        private static final int NULL_INODE = 2;
+        private static final int ZERO_INODE = 3;
+        private static final int FD_INODE = 4;
+        private static final int FD_INODES = 32;
+        
+        private abstract class DevFStat extends FStat {
+            public int dev() { return devno; }
+            public int mode() { return 0666; }
+            public int type() { return S_IFCHR; }
+            public int nlink() { return 1; }
+            public abstract int inode();
+        }
+        
+        private abstract class DevDirFD extends DirFD {
+            public int myDev() { return devno; }
+        }
+        
+        private FD devZeroFD = new FD() {
+            public int read(byte[] a, int off, int length) { 
+                /*Arrays.fill(a,off,off+length,(byte)0);*/
+                for(int i=off;i<off+length;i++) a[i] = 0;
+                return length;
+            }
+            public int write(byte[] a, int off, int length) { return length; }
+            public int seek(int n, int whence) { return 0; }
+            public FStat _fstat() { return new DevFStat(){ public int inode() { return ZERO_INODE; } }; }
+            public int flags() { return O_RDWR; }
+        };
+        private FD devNullFD = new FD() {
+            public int read(byte[] a, int off, int length) { return 0; }
+            public int write(byte[] a, int off, int length) { return length; }
+            public int seek(int n, int whence) { return 0; }
+            public FStat _fstat() { return new DevFStat(){ public int inode() { return NULL_INODE; } }; }
+            public int flags() { return O_RDWR; }
+        }; 
+        
+        public FD open(UnixRuntime r, String path, int mode, int flags) throws ErrnoException {
             if(path.equals("null")) return devNullFD;
             if(path.equals("zero")) return devZeroFD;
-            /*if(path.startsWith("fd/")) {
+            if(path.startsWith("fd/")) {
                 int n;
                 try {
                     n = Integer.parseInt(path.substring(4));
                 } catch(NumberFormatException e) {
-                    throw new FileNotFoundException();
+                    return null;
                 }
-                if(n < 0 || n >= OPEN_MAX) throw new FileNotFoundException();
-                if(fds[n] == null) throw new FileNotFoundException();
-                return fds[n].dup();
+                if(n < 0 || n >= OPEN_MAX) return null;
+                if(r.fds[n] == null) return null;
+                return r.fds[n].dup();
             }
             if(path.equals("fd")) {
                 int count=0;
-                for(int i=0;i<OPEN_MAX;i++) if(fds[i] != null) count++; 
-                String[] files = new String[count];
+                for(int i=0;i<OPEN_MAX;i++) if(r.fds[i] != null) { count++; }
+                final int[] files = new int[count];
                 count = 0;
-                for(int i=0;i<OPEN_MAX;i++) if(fds[i] != null) files[count++] = Integer.toString(i);
-                return directoryFD(files,hashCode());
-            }*/
+                for(int i=0;i<OPEN_MAX;i++) if(r.fds[i] != null) files[count++] = i;
+                return new DevDirFD() {
+                    public int myInode() { return FD_INODE; }
+                    public int parentInode() { return ROOT_INODE; }
+                    public int inode(int n) { return FD_INODES + n; }
+                    public String name(int n) { return Integer.toString(files[n]); }
+                    public int size() { return files.length; }
+                };
+            }
             if(path.equals("")) {
-                String[] files = { "null", "zero", "fd" };
-                return directoryFD(files,hashCode());
+                return new DevDirFD() {
+                    public int myInode() { return ROOT_INODE; }
+                    // HACK: We don't have any clean way to get the parent inode
+                    public int parentInode() { return ROOT_INODE; }
+                    public int inode(int n) {
+                        switch(n) {
+                            case 0: return NULL_INODE;
+                            case 1: return ZERO_INODE;
+                            case 2: return FD_INODE;
+                            default: return -1;
+                        }
+                    }
+                    
+                    public String name(int n) {
+                        switch(n) {
+                            case 0: return "null";
+                            case 1: return "zero";
+                            case 2: return "fd";
+                            default: return null;
+                        }
+                    }
+                    public int size() { return 3; }
+                };
             }
-            throw new FileNotFoundException();
+            return null;
         }
         
-        public FStat _stat(String path) throws IOException {
+        public FStat stat(UnixRuntime r,String path) throws ErrnoException {
             if(path.equals("null")) return devNullFD.fstat();
             if(path.equals("zero")) return devZeroFD.fstat();            
-            /*if(path.startsWith("fd/")) {
+            if(path.startsWith("fd/")) {
                 int n;
                 try {
-                    n = Integer.parseInt(path.substring(4));
+                    n = Integer.parseInt(path.substring(3));
                 } catch(NumberFormatException e) {
-                    throw new FileNotFoundException();
+                    return null;
                 }
-                if(n < 0 || n >= OPEN_MAX) throw new FileNotFoundException();
-                if(fds[n] == null) throw new FileNotFoundException();
-                return fds[n].fstat();
+                if(n < 0 || n >= OPEN_MAX) return null;
+                if(r.fds[n] == null) return null;
+                return r.fds[n].fstat();
             }
-            if(path.equals("fd")) return new FStat() { public int type() { return S_IFDIR; } public int mode() { return 0444; }};
-            */
-            if(path.equals("")) return new FStat() { public int type() { return S_IFDIR; } public int mode() { return 0444; }};
-            throw new FileNotFoundException();
+            if(path.equals("fd")) return new FStat() { public int inode() { return FD_INODE; }   public int dev() { return devno; } public int type() { return S_IFDIR; } public int mode() { return 0444; }};
+            if(path.equals(""))   return new FStat() { public int inode() { return ROOT_INODE; } public int dev() { return devno; } public int type() { return S_IFDIR; } public int mode() { return 0444; }};
+            return null;
         }
         
-        public void _mkdir(String path) throws IOException { throw new ErrnoException(EACCES); }
+        public void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException { throw new ErrnoException(EROFS); }
+        public void unlink(UnixRuntime r, String path) throws ErrnoException { throw new ErrnoException(EROFS); }
+    }
+    
+    
+    public static class ResourceFS extends FS {
+        final InodeCache inodes = new InodeCache(500);
+        
+        public FStat lstat(UnixRuntime r, String path) throws ErrnoException { return stat(r,path); }
+        public void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException { throw new ErrnoException(EROFS); }
+        public void unlink(UnixRuntime r, String path) throws ErrnoException { throw new ErrnoException(EROFS); }
+        
+        FStat connFStat(final URLConnection conn) {
+            return new FStat() {
+                public int type() { return S_IFREG; }
+                public int nlink() { return 1; }
+                public int mode() { return 0444; }
+                public int size() { return conn.getContentLength(); }
+                public int mtime() { return (int)(conn.getDate() / 1000); }
+                public int inode() { return inodes.get(conn.getURL().toString()); }
+                public int dev() { return devno; }
+            };
+        }
+        
+        public FStat stat(UnixRuntime r, String path) throws ErrnoException {
+            URL url = r.getClass().getResource("/" + path);
+            if(url == null) return null;
+            try {
+                return connFStat(url.openConnection());
+            } catch(IOException e) {
+                throw new ErrnoException(EIO);
+            }
+        }
+        
+        public FD open(UnixRuntime r, String path, int flags, int mode) throws ErrnoException {
+            if((flags & ~3) != 0) {
+                if(STDERR_DIAG)
+                    System.err.println("WARNING: Unsupported flags passed to ResourceFS.open(\"" + path + "\"): " + toHex(flags & ~3));
+                throw new ErrnoException(ENOTSUP);
+            }
+            if((flags&3) != RD_ONLY) throw new ErrnoException(EROFS);
+            URL url = r.getClass().getResource("/" + path);
+            if(url == null) return null;
+            try {
+                final URLConnection conn = url.openConnection();
+                Seekable.InputStream si = new Seekable.InputStream(conn.getInputStream());
+                return new SeekableFD(si,flags) { protected FStat _fstat() { return connFStat(conn); } };
+            } catch(FileNotFoundException e) {
+                if(e.getMessage() != null && e.getMessage().indexOf("Permission denied") >= 0) throw new ErrnoException(EACCES);
+                return null;
+            } catch(IOException e) { throw new ErrnoException(EIO); }
+        }
     }
 }