X-Git-Url: http://git.megacz.com/?p=nestedvm.git;a=blobdiff_plain;f=src%2Forg%2Fibex%2Fnestedvm%2FUnixRuntime.java;h=adddc51ff21b05617746a2c803ff38d89779be49;hp=a4b1991dde398d7182d6c2b05b1d0ce1a9992c3d;hb=b8372da83bb6fe6064c1f6387411a5b2af9f4e7b;hpb=615390526d6598c4124370fdd77b55894413cd1d

diff --git a/src/org/ibex/nestedvm/UnixRuntime.java b/src/org/ibex/nestedvm/UnixRuntime.java
index a4b1991..adddc51 100644
--- a/src/org/ibex/nestedvm/UnixRuntime.java
+++ b/src/org/ibex/nestedvm/UnixRuntime.java
@@ -1,9 +1,14 @@
+// Copyright 2000-2005 the Contributors, as shown in the revision logs.
+// Licensed under the Apache 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.*;
 import java.io.*;
 import java.util.*;
 import java.net.*;
+import java.lang.reflect.*; // For lazily linked RuntimeCompiler
 
 // FEATURE: vfork
 
@@ -14,9 +19,10 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     public final int getPid() { return pid; }
     
     private static final GlobalState defaultGS = new GlobalState();
-    private GlobalState gs = defaultGS;
+    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;
     }
     
@@ -31,14 +37,17 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     private Vector activeChildren;
     private Vector exitedChildren;
     
-    protected UnixRuntime(int pageSize, int totalPages) {
-        super(pageSize,totalPages);
+    protected UnixRuntime(int pageSize, int totalPages) { this(pageSize,totalPages,false); }
+    protected UnixRuntime(int pageSize, int totalPages, boolean exec) {
+        super(pageSize,totalPages,exec);
                 
-        // FEATURE: Do the proper mangling for non-unix hosts
-        String userdir = getSystemProperty("user.dir");
-        cwd = 
-            userdir != null && userdir.startsWith("/") && File.separatorChar == '/' && getSystemProperty("nestedvm.root") == null
-            ? userdir.substring(1) : "";
+        if(!exec) {
+            gs = defaultGS;
+            String userdir = Platform.getProperty("user.dir");
+            cwd = userdir == null ? null : gs.mapHostPath(userdir);
+            if(cwd == null) cwd = "/";
+            cwd = cwd.substring(1);
+        }
     }
     
     private static String posixTZ() {
@@ -63,15 +72,18 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
     
     String[] createEnv(String[] extra) {
-        String[] defaults = new String[6];
+        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.home") != 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=gs.mapHostPath(tmp)) != null)
+            defaults[n++] = "HOME=" + tmp;
+        if(!envHas("TMPDIR",extra) && (tmp=Platform.getProperty("java.io.tmpdir")) != null && (tmp=gs.mapHostPath(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];
@@ -134,19 +146,70 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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_fcntl: return sys_fcntl_lock(a,b,c);
+            case SYS_umask: return sys_umask(a);
+            
             default: return super._syscall(syscall,a,b,c,d,e,f);
         }
     }
     
     FD _open(String path, int flags, int mode) throws ErrnoException {
-        return gs.open(this,normalizePath(path),flags,mode);
+        path = normalizePath(path);
+        FD fd = gs.open(this,path,flags,mode);
+        if (fd != null && path != null) fd.setNormalizedPath(path);
+        return fd;
     }
     
     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,normalizePath(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: 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.
@@ -162,16 +225,13 @@ 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:
-                // FEATURE: This is ugly, make a clean interface to sys_exit
-                return syscall(SYS_exit,128+signal,0,0,0,0,0);
+                exit(128+signal, true);
         }
         return 0;
     }
@@ -198,6 +258,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                         exitedChildren.removeElementAt(exitedChildren.size() - 1);
                     }
                 } 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) {
@@ -263,9 +324,6 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
 
     private int sys_fork() {
-        CPUState state = new CPUState();
-        getCPUState(state);
-        int sp = state.r[SP];
         final UnixRuntime r;
         
         try {
@@ -291,6 +349,8 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         }
         activeChildren.addElement(r);
         
+        CPUState state = new CPUState();
+        getCPUState(state);
         state.r[V0] = 0; // return 0 to child
         state.pc += 4; // skip over syscall instruction
         r.setCPUState(state);
@@ -332,42 +392,156 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     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 {
+            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;
+    }
+            
+    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;
+        }
         
-    private int exec(String normalizedPath, String[] argv, String[] envp) throws ErrnoException {
+        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 {
             System.err.println("Execing normalized path: " + normalizedPath);
             if(true) return exec(new Interpreter(normalizedPath),argv,envp);
         } catch(IOException e) { throw new Error(e); }*/
         
-        Object o = gs.exec(this,normalizedPath);
-        if(o == null) return -ENOENT;
-
-        if(o instanceof Class) {
-            Class c = (Class) o;
-            try {
-                return exec((UnixRuntime) c.newInstance(),argv,envp);
-            } catch(Exception e) {
-                e.printStackTrace();
-                return -ENOEXEC;
+        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");
             }
-        } else {
-            String[] command = (String[]) o;
-            String[] newArgv = new String[argv.length + command[1] != null ? 2 : 1];
-            int p = command[0].lastIndexOf('/');
-            newArgv[0] = p == -1 ? command[0] : command[0].substring(p+1);
-            p = 1;
-            if(command[1] != null) newArgv[p++] = command[1];
-            newArgv[p++] = "/" + normalizedPath;
-            for(int i=1;i<argv.length;i++) newArgv[p++] = argv[i];
-            return exec(command[0],newArgv,envp);
+            //System.err.println("Cache was out of date");
+            gs.execCache.remove(path);
+        }
+        
+        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();
+        }        
+    }
+    
+    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 {
+            UnixRuntime r = (UnixRuntime) c.getDeclaredConstructor(new Class[]{Boolean.TYPE}).newInstance(new Object[]{Boolean.TRUE});
+            return exec(r,argv,envp);
+        } catch(Exception e) {
+            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;
@@ -389,9 +563,6 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         return 0;   
     }
     
-    // FEATURE: Make sure fstat info is correct
-    // FEATURE: This could be faster if we did direct copies from each process' memory
-    // FEATURE: Check this logic one more time
     public static class Pipe {
         private final byte[] pipebuf = new byte[PIPE_BUF*4];
         private int readPos;
@@ -401,7 +572,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public final FD writer = new Writer();
         
         public class Reader extends FD {
-            protected FStat _fstat() { return new FStat(); }
+            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) {
@@ -416,11 +587,12 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                     return len;
                 }
             }
+            public int flags() { return O_RDONLY; }
             public void _close() { synchronized(Pipe.this) { readPos = -1; Pipe.this.notify(); } }
         }
         
         public class Writer extends FD {   
-            protected FStat _fstat() { return new FStat(); }
+            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) {
@@ -440,6 +612,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                     return len;
                 }
             }
+            public int flags() { return O_WRONLY; }
             public void _close() { synchronized(Pipe.this) { writePos = -1; Pipe.this.notify(); } }
         }
     }
@@ -532,9 +705,170 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         copyout(buf,addr,n);
         return n;
     }
-    
-    // FIXME: UDP is totally broken
-    
+
+    void _preCloseFD(FD fd) {
+        // release all fcntl locks on this file
+        Seekable s = fd.seekable();
+        if (s == null) return;
+
+        try {
+            for (int i=0; i < gs.locks.length; i++) {
+                Seekable.Lock l = gs.locks[i];
+                if (l == null) continue;
+                if (s.equals(l.seekable()) && l.getOwner() == this) {
+                    l.release();
+                    gs.locks[i] = null;
+                }
+            }
+        } catch (IOException e) { throw new RuntimeException(e); }
+    }
+
+    void _postCloseFD(FD fd) {
+        if (fd.isMarkedForDeleteOnClose()) {
+            try { gs.unlink(this, fd.getNormalizedPath()); }
+            catch (Throwable t) {}
+        }
+    }
+
+    /** Implements the F_GETLK and F_SETLK cases of fcntl syscall.
+     *  If l_start = 0 and l_len = 0 the lock refers to the entire file.
+     *  Uses GlobalState to ensure locking across processes in the same JVM.
+     struct flock {
+       short   l_type;         // lock type: F_UNLCK, F_RDLCK, F_WRLCK
+       short   l_whence;       // type of l_start: SEEK_SET, SEEK_CUR, SEEK_END
+       long    l_start;        // starting offset, bytes
+       long    l_len;          // len = 0 means until EOF
+       short   l_pid;          // lock owner
+       short   l_xxx;          // padding
+     };
+     */
+    private int sys_fcntl_lock(int fdn, int cmd, int arg) throws FaultException{
+        if (cmd != F_GETLK && cmd != F_SETLK) return sys_fcntl(fdn, cmd, arg);
+
+        if(fdn < 0 || fdn >= OPEN_MAX) return -EBADFD;
+        if(fds[fdn] == null) return -EBADFD;
+        FD fd = fds[fdn];
+
+        if (arg == 0) return -EINVAL;
+        int word     = memRead(arg);
+        int l_start  = memRead(arg+4);
+        int l_len    = memRead(arg+8);
+        int l_type   = word>>16;
+        int l_whence = word&0x00ff;
+
+        Seekable.Lock[] locks = gs.locks;
+        Seekable s = fd.seekable();
+        if (s == null) return -EINVAL;
+
+        try {
+
+        switch (l_whence) {
+            case SEEK_SET: break;
+            case SEEK_CUR: l_start += s.pos(); break;
+            case SEEK_END: l_start += s.length(); break;
+            default: return -1;
+        }
+
+        if (cmd == F_GETLK) {
+            // The simple Java file locking below will happily return
+            // a lock that overlaps one already held by the JVM. Thus
+            // we must check over all the locks held by other Runtimes
+            for (int i=0; i < locks.length; i++) {
+                if (locks[i] == null || !s.equals(locks[i].seekable()))
+                    continue;
+                if (!locks[i].overlaps(l_start, l_len))
+                    continue;
+                if (locks[i].getOwner() == this)
+                    continue;
+                if (locks[i].isShared() && l_type == F_RDLCK)
+                    continue;
+
+                // overlapping lock held by another process
+                return 0;
+            }
+
+            // check if an area is lockable by attempting to obtain a lock
+            Seekable.Lock lock = s.lock(l_start, l_len, l_type == F_RDLCK);
+
+            if (lock != null) { // no lock exists
+                memWrite(arg, SEEK_SET|(F_UNLCK<<16));
+                lock.release();
+            }
+
+            return 0;
+        }
+
+        // now processing F_SETLK
+        if (cmd != F_SETLK) return -EINVAL;
+
+        if (l_type == F_UNLCK) {
+            // release all locks that fall within the boundaries given
+            for (int i=0; i < locks.length; i++) {
+                if (locks[i] == null || !s.equals(locks[i].seekable()))
+                    continue;
+                if (locks[i].getOwner() != this) continue;
+
+                int pos = (int)locks[i].position();
+                if (pos < l_start) continue;
+                if (l_start != 0 && l_len != 0) // start/len 0 means unlock all
+                    if (pos + locks[i].size() > l_start + l_len)
+                        continue;
+
+                locks[i].release();
+                locks[i] = null;
+            }
+            return 0;
+
+        } else if (l_type == F_RDLCK || l_type == F_WRLCK) {
+            // first see if a lock already exists
+            for (int i=0; i < locks.length; i++) {
+                if (locks[i] == null || !s.equals(locks[i].seekable()))
+                    continue;
+
+                if (locks[i].getOwner() == this) {
+                    // if this Runtime owns an overlapping lock work with it
+                    if (locks[i].contained(l_start, l_len)) {
+                        locks[i].release();
+                        locks[i] = null;
+                    } else if (locks[i].contains(l_start, l_len)) {
+                        if (locks[i].isShared() == (l_type == F_RDLCK)) {
+                            // return this more general lock
+                            memWrite(arg+4, (int)locks[i].position());
+                            memWrite(arg+8, (int)locks[i].size());
+                            return 0;
+                        } else {
+                            locks[i].release();
+                            locks[i] = null;
+                        }
+                    }
+                } else {
+                    // if another Runtime has an lock and it is exclusive or
+                    // we want an exclusive lock then fail
+                    if (locks[i].overlaps(l_start, l_len)
+                            && (!locks[i].isShared() || l_type == F_WRLCK))
+                        return -EAGAIN;
+                }
+            }
+
+            // create the lock
+            Seekable.Lock lock = s.lock(l_start, l_len, l_type == F_RDLCK);
+            if (lock == null) return -EAGAIN;
+            lock.setOwner(this);
+
+            int i;
+            for (i=0; i < locks.length; i++)
+                if (locks[i] == null) break;
+            if (i == locks.length) return -ENOLCK;
+            locks[i] = lock;
+            return 0;
+
+        } else {
+            return -EINVAL;
+        }
+
+        } catch (IOException e) { throw new RuntimeException(e); }
+    }
+
     static class SocketFD extends FD {
         public static final int TYPE_STREAM = 0;
         public static final int TYPE_DGRAM = 1;
@@ -544,19 +878,31 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         
         int flags;
         int options;
-        Object o;
+        
+        Socket s;
+        ServerSocket ss;
+        DatagramSocket ds;
+        
         InetAddress bindAddr;
         int bindPort = -1;
+        InetAddress connectAddr;
+        int connectPort = -1;
+        
         DatagramPacket dp;
         InputStream is;
         OutputStream os; 
         
-        public SocketFD(int type) { flags = type; }
+        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(o != null && type() == TYPE_STREAM && !listen()) {
-                    Platform.socketSetKeepAlive((Socket)o,(options & SO_KEEPALIVE) != 0);
+                if(s != null && type() == TYPE_STREAM && !listen()) {
+                    Platform.socketSetKeepAlive(s,(options & SO_KEEPALIVE) != 0);
                 }
             } catch(SocketException e) {
                 if(STDERR_DIAG) e.printStackTrace();
@@ -564,76 +910,87 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         }
         
         public void _close() {
-            if(o != null) {
-                try {
-                    if(type() == TYPE_STREAM) {
-                        if(listen()) ((ServerSocket)o).close();
-                        else ((Socket)o).close();
-                    } else {
-                        ((DatagramSocket)o).close();
-                    }
-                } catch(IOException e) {
-                    /* ignore */
-                }
+            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_STREAM) {
-                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);
-                }
-            } else {
-                if(off != 0) throw new IllegalArgumentException("off must be 0");
-                DatagramSocket ds = (DatagramSocket) o;
-                dp.setData(a);
-                dp.setLength(length);
-                try {
-                    ds.receive(dp);
-                } catch(IOException e) {
-                    throw new ErrnoException(EIO);
-                }
-                return dp.getLength();
+            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 write(byte[] a, int off, int length) throws ErrnoException {
-            if(type() == TYPE_STREAM) {
-                if(os == null) throw new ErrnoException(EPIPE);
-                try {
-                    os.write(a,off,length);
-                    return length;
-                } catch(IOException e) {
-                    throw new ErrnoException(EIO);
-                }
-            } else {
-                if(off != 0) throw new IllegalArgumentException("off must be 0");
-                DatagramSocket ds = (DatagramSocket) o;
-                dp.setData(a);
-                dp.setLength(length);
-                try {
-                    ds.send(dp);
-                } catch(IOException e) {
-                    throw new ErrnoException(EIO);
-                }
-                return dp.getLength();
-            }
+        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);
 
-        // FEATURE: Check that these are correct
-        public int flags() {
-            if(is != null && os != null) return O_RDWR;
-            if(is != null) return O_RDONLY;
-            if(os != null) return O_WRONLY;
-            return 0;
+            if(os == null) throw new ErrnoException(EPIPE);
+            try {
+                os.write(a,off,length);
+                return length;
+            } catch(IOException e) {
+                throw new ErrnoException(EIO);
+            }
         }
         
-        // FEATURE: Populate this properly
-        public FStat _fstat() { return new FStat(); }
+        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) {
@@ -652,7 +1009,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     private int sys_connect(int fdn, int addr, int namelen) throws ErrnoException, FaultException {
         SocketFD fd = getSocketFD(fdn);
         
-        if(fd.type() == SocketFD.TYPE_STREAM && fd.o != null) return -EISCONN;
+        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;
@@ -666,22 +1023,21 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             return -EADDRNOTAVAIL;
         }
         
+        fd.connectAddr = inetAddr;
+        fd.connectPort = port;
+        
         try {
             switch(fd.type()) {
                 case SocketFD.TYPE_STREAM: {
                     Socket s = new Socket(inetAddr,port);
-                    fd.o = s;
+                    fd.s = s;
                     fd.setOptions();
                     fd.is = s.getInputStream();
                     fd.os = s.getOutputStream();
                     break;
                 }
-                case SocketFD.TYPE_DGRAM: {
-                    if(fd.dp == null) fd.dp = new DatagramPacket(null,0);
-                    fd.dp.setAddress(inetAddr);
-                    fd.dp.setPort(port);
+                case SocketFD.TYPE_DGRAM:
                     break;
-                }
                 default:
                     throw new Error("should never happen");
             }
@@ -761,7 +1117,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     private int sys_bind(int fdn, int addr, int namelen) throws FaultException, ErrnoException {
         SocketFD fd = getSocketFD(fdn);
         
-        if(fd.type() == SocketFD.TYPE_STREAM && fd.o != null) return -EISCONN;
+        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;
@@ -784,10 +1140,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                 return 0;
             }
             case SocketFD.TYPE_DGRAM: {
-                DatagramSocket s = (DatagramSocket) fd.o;
-                if(s != null) s.close();
+                if(fd.ds != null) fd.ds.close();
                 try {
-                    fd.o = inetAddr != null ? new DatagramSocket(port,inetAddr) : new DatagramSocket(port);
+                    fd.ds = inetAddr != null ? new DatagramSocket(port,inetAddr) : new DatagramSocket(port);
                 } catch(IOException e) {
                     return -EADDRINUSE;
                 }
@@ -801,11 +1156,11 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     private int sys_listen(int fdn, int backlog) throws ErrnoException {
         SocketFD fd = getSocketFD(fdn);
         if(fd.type() != SocketFD.TYPE_STREAM) return -EOPNOTSUPP;
-        if(fd.o != null) return -EISCONN;
+        if(fd.ss != null || fd.s != null) return -EISCONN;
         if(fd.bindPort < 0) return -EOPNOTSUPP;
         
         try {
-            fd.o = new ServerSocket(fd.bindPort,backlog,fd.bindAddr);
+            fd.ss = new ServerSocket(fd.bindPort,backlog,fd.bindAddr);
             fd.flags |= SocketFD.LISTEN;
             return 0;
         } catch(IOException e) {
@@ -821,7 +1176,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
 
         int size = memRead(lenaddr);
         
-        ServerSocket s = (ServerSocket) fd.o;
+        ServerSocket s = fd.ss;
         Socket client;
         try {
             client = s.accept();
@@ -837,7 +1192,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         }
         
         SocketFD clientFD = new SocketFD(SocketFD.TYPE_STREAM);
-        clientFD.o = client;
+        clientFD.s = client;
         try {
             clientFD.is = client.getInputStream();
             clientFD.os = client.getOutputStream();
@@ -852,9 +1207,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     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.o == null) return -ENOTCONN;
+        if(fd.s == null) return -ENOTCONN;
         
-        Socket s = (Socket) fd.o;
+        Socket s = fd.s;
         
         try {
             if(how == SHUT_RD || how == SHUT_RDWR) Platform.socketHalfClose(s,false);
@@ -866,6 +1221,58 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         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();
@@ -913,66 +1320,16 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         }
         return 0;
     }
-        
     
-    /*public int sys_opensocket(int cstring, int port) throws FaultException, ErrnoException {
-        String hostname = cstring(cstring);
-        try {
-            FD fd = new SocketFD(new Socket(hostname,port));
-            int n = addFD(fd);
-            if(n == -1) fd.close();
-            return n;
-        } catch(IOException e) {
-            return -EIO;
-        }
-    }
-    
-    private static class ListenSocketFD extends FD {
-        ServerSocket s;
-        public ListenSocketFD(ServerSocket s) { this.s = s; }
-        public int flags() { return 0; }
-        // FEATURE: What should these be?
-        public FStat _fstat() { return new FStat(); }
-        public void _close() { try { s.close(); } catch(IOException e) { } }
-    }
-    
-    public int sys_listensocket(int port) {
-        try {
-            ListenSocketFD fd = new ListenSocketFD(new ServerSocket(port));
-            int n = addFD(fd);
-            if(n == -1) fd.close();
-            return n;            
-        } catch(IOException e) {
-            return -EIO;
-        }
-    }
-    
-    public int sys_accept(int fdn) {
-        if(fdn < 0 || fdn >= OPEN_MAX) return -EBADFD;
-        if(fds[fdn] == null) return -EBADFD;
-        if(!(fds[fdn] instanceof ListenSocketFD)) return -EBADFD;
-        try {
-            ServerSocket s = ((ListenSocketFD)fds[fdn]).s;
-            SocketFD fd = new SocketFD(s.accept());
-            int n = addFD(fd);
-            if(n == -1) fd.close();
-            return n;
-        } catch(IOException e) {
-            return -EIO;
-        }
-    }*/
-    
-    //  FEATURE: Run through the fork/wait stuff one more time
-    public static class GlobalState {    
-        protected static final int OPEN = 1;
-        protected static final int STAT = 2;
-        protected static final int LSTAT = 3;
-        protected static final int MKDIR = 4;
-        protected static final int UNLINK = 5;
+    public static final class GlobalState {
+        Hashtable execCache = new Hashtable();
         
         final UnixRuntime[] tasks;
         int nextPID = 1;
         
+        /** Table of all current file locks held by this process. */
+        Seekable.Lock[] locks = new Seekable.Lock[16];
+
         private MP[] mps = new MP[0];
         private FS root;
         
@@ -981,12 +1338,65 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public GlobalState(int maxProcs, boolean defaultMounts) {
             tasks = new UnixRuntime[maxProcs+1];
             if(defaultMounts) {
-                addMount("/",new HostFS());
+                File root = null;
+                if(Platform.getProperty("nestedvm.root") != null) {
+                    root = new File(Platform.getProperty("nestedvm.root"));
+                    if(!root.isDirectory()) throw new IllegalArgumentException("nestedvm.root is not a directory");
+                } else {
+                    String cwd = Platform.getProperty("user.dir");
+                    root = Platform.getRoot(new File(cwd != null ? cwd : "."));
+                }
+                
+                addMount("/",new HostFS(root));
+                
+                if(Platform.getProperty("nestedvm.root") == null) {
+                    File[] roots = Platform.listRoots();
+                    for(int i=0;i<roots.length;i++) {
+                        String name = roots[i].getPath();
+                        if(name.endsWith(File.separator))
+                            name = name.substring(0,name.length()-1);
+                        if(name.length() == 0 || name.indexOf('/') != -1) continue;
+                        addMount("/" + name.toLowerCase(),new HostFS(roots[i]));
+                    }
+                }
+                
                 addMount("/dev",new DevFS());
+                addMount("/resource",new ResourceFS());
+                addMount("/cygdrive",new CygdriveFS());
             }
         }
         
-        private static class MP implements Sort.Comparable {
+        public String mapHostPath(String s) { return mapHostPath(new File(s)); }
+        public String mapHostPath(File f) {
+            MP[] list;
+            FS root;
+            synchronized(this) { mps = this.mps; root = this.root; }
+            if(!f.isAbsolute()) f = new File(f.getAbsolutePath());
+            for(int i=mps.length;i>=0;i--) {
+                FS fs = i == mps.length ? root : mps[i].fs;
+                String path = i == mps.length ? "" : mps[i].path;
+                if(!(fs instanceof HostFS)) continue;
+                File fsroot = ((HostFS)fs).getRoot();
+                if(!fsroot.isAbsolute()) fsroot = new File(fsroot.getAbsolutePath());
+                if(f.getPath().startsWith(fsroot.getPath())) {
+                    char sep = File.separatorChar;
+                    String child = f.getPath().substring(fsroot.getPath().length());
+                    if(sep != '/') {
+                        char[] child_ = child.toCharArray();
+                        for(int j=0;j<child_.length;j++) {
+                            if(child_[j] == '/') child_[j] = sep;
+                            else if(child_[j] == sep) child_[j] = '/';
+                        }
+                        child = new String(child_);
+                    }
+                    String mapped = "/" + (path.length()==0?"":path+"/") + child;
+                    return mapped;
+                }
+            }
+            return null;
+        }
+        
+        static class MP implements Sort.Comparable {
             public MP(String path, FS fs) { this.path = path; this.fs = fs; }
             public String path;
             public FS fs;
@@ -1050,7 +1460,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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) {
@@ -1059,136 +1469,48 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                 for(int i=0;i<list.length;i++) {
                     MP mp = list[i];
                     int mpl = mp.path.length();
-                    if(normalizedPath.startsWith(mp.path) && (pl == mpl || (pl < mpl && normalizedPath.charAt(mpl) == '/')))
-                        return dispatch(mp.fs,op,r,pl == mpl ? "" : normalizedPath.substring(mpl+1),arg1,arg2);
+                    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 dispatch(root,op,r,normalizedPath,arg1,arg2);
-        }
-        
-        private static Object dispatch(FS fs, int op, UnixRuntime r, String path, int arg1, int arg2) throws ErrnoException {
-            switch(op) {
-                case OPEN: return fs.open(r,path,arg1,arg2);
-                case STAT: return fs.stat(r,path);
-                case LSTAT: return fs.lstat(r,path);
-                case MKDIR: fs.mkdir(r,path,arg1); return null;
-                case UNLINK: fs.unlink(r,path); return null;
-                default: throw new Error("should never happen");
-            }
+            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(OPEN,r,path,flags,mode); }
-        public final FStat stat(UnixRuntime r, String path) throws ErrnoException { return (FStat) fsop(STAT,r,path,0,0); }
-        public final FStat lstat(UnixRuntime r, String path) throws ErrnoException { return (FStat) fsop(LSTAT,r,path,0,0); }
-        public final void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException { fsop(MKDIR,r,path,mode,0); }
-        public final void unlink(UnixRuntime r, String path) throws ErrnoException { fsop(UNLINK,r,path,0,0); }
+        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 Hashtable execCache = new Hashtable();
         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 synchronized Object exec(UnixRuntime r, String path) throws ErrnoException {
-            // FIXME: Hideous hack to make a standalone busybox possible
-            if(path.equals("bin/busybox") && Boolean.valueOf(getSystemProperty("nestedvm.busyboxhack")).booleanValue())
-                return r.getClass();
-            FStat fstat = stat(r,path);
-            if(fstat == null) return null;
-            long mtime = fstat.mtime();
-            long size = fstat.size();
-            CacheEnt ent = (CacheEnt) execCache.get(path);
-            if(ent != null) {
-                //System.err.println("Found cached entry for " + path);
-                if(ent.time == mtime && ent.size == size) return ent.o;
-                //System.err.println("Cache was out of date");
-                execCache.remove(path);
-            }
-            FD fd = open(r,path,RD_ONLY,0);
-            if(fd == null) return null;
-            Seekable s = fd.seekable();
-            
-            String[] command  = null;
-
-            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) != 4-n) throw new ErrnoException(ENOEXEC);
-                        if(buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F') throw new ErrnoException(ENOEXEC);
-                        break;
-                    case '#':
-                        if(n == 1) {
-                            int n2 = s.read(buf,1,buf.length-1);
-                            if(n2 == -1) throw new ErrnoException(ENOEXEC);
-                            n += n2;
-                        }
-                        if(buf[1] != '!') throw new ErrnoException(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);
-                        }
-                        command = new String[2];
-                        int arg;
-                        for(arg=2;arg<p;arg++) if(buf[arg] == ' ') break;
-                        if(arg < p) {
-                            int cmdEnd = arg;
-                            while(arg < p && buf[arg] == ' ') arg++;
-                            command[0] = new String(buf,2,cmdEnd);
-                            command[1] = arg < p ? new String(buf,arg,p-arg) : null;
-                        } else {
-                            command[0] = new String(buf,2,p-2);
-                        }
-                        //System.err.println("command[0]: " + command[0] + " command[1]: " + command[1]);
-                        break;
-                    default:
-                        throw new ErrnoException(ENOEXEC);
-                }
-            } catch(IOException e) {
-                fd.close();
-                throw new ErrnoException(EIO);
-            }
-                        
-            if(command == null) {
-                // its an elf binary
-                try {
-                    s.seek(0);
-                    Class c = RuntimeCompiler.compile(s);
-                    //System.err.println("Compile succeeded: " + c);
-                    ent = new CacheEnt(mtime,size,c);
-                } catch(Compiler.Exn e) {
-                    if(STDERR_DIAG) e.printStackTrace();
-                    throw new ErrnoException(ENOEXEC);
-                } catch(IOException e) {
-                    if(STDERR_DIAG) e.printStackTrace();
-                    throw new ErrnoException(EIO);
-                }
-            } else {
-                ent = new CacheEnt(mtime,size,command);
-            }
-            
-            fd.close();
-            
-            execCache.put(path,ent);
-            return ent.o;
-        }
     }
     
     public abstract static class FS {
+        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
@@ -1199,16 +1521,18 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public abstract void unlink(UnixRuntime r, String path) throws ErrnoException;
     }
         
-    // FEATURE: chroot support in here
+    // chroot support should go in here if it is ever implemented
     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) {
@@ -1217,30 +1541,36 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             cwd.getChars(0,cwdl,out,0);
             outp = cwdl;
         }
-            
-        path.getChars(0,path.length(),in,0);
+
         while(in[inp] != 0) {
-            if(inp != 0 || cwdl==0) {
-                if(in[inp] != '/') { out[outp++] = in[inp++]; continue; }
+            if(inp != 0) {
+                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 /..{$,/}
                 inp += 2;
                 if(outp > 0) outp--;
                 while(outp > 0 && out[outp] != '/') outp--;
                 //System.err.println("After ..: " + new String(out,0,outp));
                 continue;
             }
+            // Just read a /.[^.] or /..[^/$]
             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);
     }
     
     FStat hostFStat(final File f, Object data) {
@@ -1272,21 +1602,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         protected File root;
         public File getRoot() { return root; }
         
-        private static File hostRootDir() {
-            if(getSystemProperty("nestedvm.root") != null) {
-                File f = new File(getSystemProperty("nestedvm.root"));
-                if(f.isDirectory()) return f;
-                // fall through to case below
-            }
-            String cwd = getSystemProperty("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());
-            return f;
-        }
-        
-        private File hostFile(String path) {
+        protected File hostFile(String path) {
             char sep = File.separatorChar;
             if(sep != '/') {
                 char buf[] = path.toCharArray();
@@ -1300,11 +1616,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             return new File(root,path);
         }
         
-        public HostFS() { this(hostRootDir()); }
         public HostFS(String root) { this(new File(root)); }
         public HostFS(File root) { this.root = root; }
         
-        
         public FD open(UnixRuntime r, String path, int flags, int mode) throws ErrnoException {
             final File f = hostFile(path);
             return r.hostFSOpen(f,flags,mode,this);
@@ -1314,7 +1628,21 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             File f = hostFile(path);
             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);
+            if(!f.delete()) {
+                // Can't delete file immediately, so mark for
+                // delete on close all matching FDs
+                boolean marked = false;
+                for(int i=0;i<OPEN_MAX;i++) {
+                    if(r.fds[i] != null) {
+                        String fdpath = r.fds[i].getNormalizedPath();
+                        if(fdpath != null && fdpath.equals(path)) {
+                            r.fds[i].markDeleteOnClose();
+                            marked = true;
+                        }
+                    }
+                }
+                if(!marked) throw new ErrnoException(EPERM);
+            }
         }
         
         public FStat stat(UnixRuntime r, String path) throws ErrnoException {
@@ -1336,7 +1664,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         
         private static File getParentFile(File f) {
             String p = f.getParent();
-            return p == null ? null : new File(f,p);
+            return p == null ? null : new File(p);
         }
         
         public class HostDirFD extends DirFD {
@@ -1353,12 +1681,30 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             public int inode(int n) { return inodes.get(children[n].getAbsolutePath()); }
             public int parentInode() {
                 File parent = getParentFile(f);
-                return parent == null ? -1 : inodes.get(parent.getAbsolutePath());
+                // 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; } 
         }
     }
+
+    /* Implements the Cygwin notation for accessing MS Windows drive letters
+     * in a unix path. The path /cygdrive/c/myfile is converted to C:\file.
+     * As there is no POSIX standard for this, little checking is done. */
+    public static class CygdriveFS extends HostFS {
+        protected File hostFile(String path) {
+            final char drive = path.charAt(0);
+
+            if (drive < 'a' || drive > 'z' || path.charAt(1) != '/')
+                return null;
+
+            path = drive + ":" + path.substring(1).replace('/', '\\');
+            return new File(path);
+        }
+
+        public CygdriveFS() { super("/"); }
+    }
     
     private static void putInt(byte[] buf, int off, int n) {
         buf[off+0] = (byte)((n>>>24)&0xff);
@@ -1374,9 +1720,10 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         protected abstract String name(int n);
         protected abstract int inode(int n);
         protected abstract int myDev();
-        protected int parentInode() { return -1; }
-        protected int myInode() { return -1; }
-        
+        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;
@@ -1427,11 +1774,12 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         private static final int FD_INODE = 4;
         private static final int FD_INODES = 32;
         
-        private class DevFStat extends FStat {
+        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 {
@@ -1447,12 +1795,14 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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 {
@@ -1461,7 +1811,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             if(path.startsWith("fd/")) {
                 int n;
                 try {
-                    n = Integer.parseInt(path.substring(4));
+                    n = Integer.parseInt(path.substring(3));
                 } catch(NumberFormatException e) {
                     return null;
                 }
@@ -1486,8 +1836,8 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             if(path.equals("")) {
                 return new DevDirFD() {
                     public int myInode() { return ROOT_INODE; }
-                    // FEATURE: Get the real parent inode somehow
-                    public int parentInode() { return -1; }
+                    // 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;
@@ -1517,7 +1867,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             if(path.startsWith("fd/")) {
                 int n;
                 try {
-                    n = Integer.parseInt(path.substring(4));
+                    n = Integer.parseInt(path.substring(3));
                 } catch(NumberFormatException e) {
                     return null;
                 }
@@ -1525,13 +1875,62 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                 if(r.fds[n] == null) return null;
                 return r.fds[n].fstat();
             }
-            // FEATURE: inode stuff
-            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; }};
+            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(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); }
+        }
+    }
 }