X-Git-Url: http://git.megacz.com/?p=nestedvm.git;a=blobdiff_plain;f=src%2Forg%2Fibex%2Fnestedvm%2FUnixRuntime.java;h=0bed8ed27ef330538112c773149dacc134fec68d;hp=5eb9178ce34e085a1e11ac34691a29ab56cf2013;hb=2db6b04d7557a26e3b9e7440e7968aaec262216f;hpb=98f786ce8ee1fcd9568d1c367160851d32e1c786

diff --git a/src/org/ibex/nestedvm/UnixRuntime.java b/src/org/ibex/nestedvm/UnixRuntime.java
index 5eb9178..0bed8ed 100644
--- a/src/org/ibex/nestedvm/UnixRuntime.java
+++ b/src/org/ibex/nestedvm/UnixRuntime.java
@@ -4,9 +4,7 @@ import org.ibex.nestedvm.util.*;
 import java.io.*;
 import java.util.*;
 
-// FIXME: Make plain old "mips-unknown-elf-gcc -o foo foo.c" work (modify spec file or whatever)
-
-// FEATURE: Remove System.{out,err}.printlns and throw Errors where applicable
+// FEATURE: vfork
 
 public abstract class UnixRuntime extends Runtime implements Cloneable {
     /** The pid of this "process" */
@@ -14,8 +12,12 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     private UnixRuntime parent;
     public final int getPid() { return pid; }
     
-    private static final GlobalState defaultGD = new GlobalState();
-    private GlobalState gd = defaultGD;
+    private static final GlobalState defaultGS = new GlobalState();
+    private GlobalState gs = defaultGS;
+    public void setGlobalState(GlobalState gs) {
+        if(state != STOPPED) throw new IllegalStateException("can't change GlobalState when running");
+        this.gs = gs;
+    }
     
     /** proceses' current working directory - absolute path WITHOUT leading slash
         "" = root, "bin" = /bin "usr/bin" = /usr/bin */
@@ -33,7 +35,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                 
         // FEATURE: Do the proper mangling for non-unix hosts
         String userdir = getSystemProperty("user.dir");
-        cwd = userdir != null && userdir.startsWith("/") && File.separatorChar == '/'  ? userdir.substring(1) : "";
+        cwd = 
+            userdir != null && userdir.startsWith("/") && File.separatorChar == '/' && getSystemProperty("nestedvm.root") == null
+            ? userdir.substring(1) : "";
     }
     
     // NOTE: getDisplayName() is a Java2 function
@@ -59,16 +63,17 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
     
     String[] createEnv(String[] extra) {
-        String[] defaults = new String[5];
+        String[] defaults = new String[6];
         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)
+        if(!envHas("HOME",extra) && getSystemProperty("user.home") != null)
             defaults[n++] = "HOME=" + getSystemProperty("user.home");
         if(!envHas("SHELL",extra)) defaults[n++] = "SHELL=/bin/sh";
         if(!envHas("TERM",extra))  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];
@@ -78,18 +83,25 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     private static class ProcessTableFullExn extends RuntimeException { }
     
     void _started() {
-        UnixRuntime[] tasks = gd.tasks;
-        synchronized(gd) {
+        UnixRuntime[] tasks = gs.tasks;
+        synchronized(gs) {
             if(pid != 0) {
-                if(tasks[pid] == null || tasks[pid].pid != pid) throw new Error("should never happen");
+                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.set(i,this);
+                }
             } else {
                 int newpid = -1;
-                int nextPID = gd.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;
-                gd.nextPID = 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;
             }
             tasks[pid] = this;
         }
@@ -101,6 +113,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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);
@@ -109,13 +122,19 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             case SYS_chdir: return sys_chdir(a);
             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();
 
             default: return super._syscall(syscall,a,b,c,d);
         }
     }
     
     FD _open(String path, int flags, int mode) throws ErrnoException {
-        return gd.open(this,normalizePath(path),flags,mode);
+        return gs.open(this,normalizePath(path),flags,mode);
+    }
+    
+    private int sys_getppid() {
+        return parent == null ? 1 : parent.pid;
     }
 
     /** The kill syscall.
@@ -147,16 +166,15 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
 
     private int sys_waitpid(int pid, int statusAddr, int options) throws FaultException, ErrnoException {
-        System.err.println("PID: " + this.pid + " is waiting on " + pid);
         final int WNOHANG = 1;
         if((options & ~(WNOHANG)) != 0) return -EINVAL;
         if(pid == 0 || pid < -1) {
-            System.err.println("WARNING: waitpid called with a pid of " + pid);
+            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 >= gd.tasks.length)) return -ECHILD;
+        if(pid !=-1 && (pid <= 0 || pid >= gs.tasks.length)) return -ECHILD;
         if(children == null) return blocking ? -ECHILD : 0;
         
         UnixRuntime done = null;
@@ -166,7 +184,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                 if(pid == -1) {
                     if(exitedChildren.size() > 0) done = (UnixRuntime)exitedChildren.remove(exitedChildren.size() - 1);
                 } else if(pid > 0) {
-                    UnixRuntime t = gd.tasks[pid];
+                    UnixRuntime t = gs.tasks[pid];
                     if(t.parent != this) return -ECHILD;
                     if(t.state == EXITED) {
                         if(!exitedChildren.remove(t)) throw new Error("should never happen");
@@ -174,14 +192,14 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                     }
                 } else {
                     // process group stuff, EINVAL returned above
-                	    throw new Error("should never happen");
+                        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());
+                    //System.err.println("waitpid woke up: " + exitedChildren.size());
                 } else {
-                    gd.tasks[done.pid] = null;
+                    gs.tasks[done.pid] = null;
                     break;
                 }
             }
@@ -195,7 +213,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         if(children != null) synchronized(children) {
             for(Enumeration e = exitedChildren.elements(); e.hasMoreElements(); ) {
                 UnixRuntime child = (UnixRuntime) e.nextElement();
-                    gd.tasks[child.pid] = null;
+                gs.tasks[child.pid] = null;
             }
             exitedChildren.clear();
             for(Enumeration e = activeChildren.elements(); e.hasMoreElements(); ) {
@@ -207,13 +225,13 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         
         UnixRuntime _parent = parent;
         if(_parent == null) {
-            gd.tasks[pid] = null;
+            gs.tasks[pid] = null;
         } else {
             synchronized(_parent.children) {
                 if(parent == null) {
-                    gd.tasks[pid] = null;
+                    gs.tasks[pid] = null;
                 } else {
-                    parent.activeChildren.remove(this);
+                    if(!parent.activeChildren.remove(this)) throw new Error("should never happen _exited: pid: " + pid);
                     parent.exitedChildren.add(this);
                     parent.children.notify();
                 }
@@ -222,7 +240,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
     
     protected Object clone() throws CloneNotSupportedException {
-    	    UnixRuntime r = (UnixRuntime) super.clone();
+        UnixRuntime r = (UnixRuntime) super.clone();
         r.pid = 0;
         r.parent = null;
         r.children = null;
@@ -248,10 +266,10 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         try {
             r._started();
         } catch(ProcessTableFullExn e) {
-        	    return -ENOMEM;
+            return -ENOMEM;
         }
 
-        System.err.println("fork " + pid + " -> " + r.pid + " tasks[" + r.pid + "] = " + gd.tasks[r.pid]);
+        //System.err.println("fork " + pid + " -> " + r.pid + " tasks[" + r.pid + "] = " + gd.tasks[r.pid]);
         if(children == null) {
             children = new Object();
             activeChildren = new Vector();
@@ -279,10 +297,10 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     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;
@@ -290,7 +308,7 @@ 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));
@@ -298,21 +316,27 @@ 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));
+        return exec(normalizePath(cstring(cpath)),readStringArray(cargv),readStringArray(cenvp));
     }
         
     private int exec(String normalizedPath, String[] argv, String[] envp) throws ErrnoException {
         if(argv.length == 0) argv = new String[]{""};
 
-        Object o = gd.exec(this,normalizedPath);
+        // 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);
+                return exec((UnixRuntime) c.newInstance(),argv,envp);
             } catch(Exception e) {
-            	    e.printStackTrace();
+                e.printStackTrace();
                 return -ENOEXEC;
             }
         } else {
@@ -330,7 +354,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     
     private int exec(UnixRuntime r, String[] argv, String[] envp) {     
         
-        System.err.println("Execing " + r);
+        //System.err.println("Execing " + r);
         for(int i=0;i<OPEN_MAX;i++) if(closeOnExec[i]) closeFD(i);
         r.fds = fds;
         r.closeOnExec = closeOnExec;
@@ -338,7 +362,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         fds = null;
         closeOnExec = null;
         
-        r.gd = gd;
+        r.gs = gs;
         r.sm = sm;
         r.cwd = cwd;
         r.pid = pid;
@@ -351,21 +375,69 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         return 0;   
     }
     
-    // FEATURE: Use custom PipeFD - be sure to support PIPE_BUF of data
-    private int sys_pipe(int addr) throws FaultException {
-        PipedOutputStream writerStream = new PipedOutputStream();
-        PipedInputStream readerStream;
-        try {
-             readerStream = new PipedInputStream(writerStream);
-        } catch(IOException e) {
-            return -EIO;
+    // 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;
+        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 FStat(); }
+            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 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 FStat(); }
+            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 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);
@@ -387,23 +459,37 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         return 0;
     }
     
+    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 = gd.stat(this,normalizePath(cstring(cstring)));
+        FStat s = gs.stat(this,normalizePath(cstring(cstring)));
         if(s == null) return -ENOENT;
         return stat(s,addr);
     }
     
     private int sys_lstat(int cstring, int addr) throws FaultException, ErrnoException {
-        FStat s = gd.lstat(this,normalizePath(cstring(cstring)));
+        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 {
-        gd.mkdir(this,normalizePath(cstring(cstring)),mode);
+        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) throws FaultException, ErrnoException {
         byte[] b = getBytes(cwd);
         if(size == 0) return -EINVAL;
@@ -416,10 +502,10 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     
     private int sys_chdir(int addr) throws ErrnoException, FaultException {
         String path = normalizePath(cstring(addr));
-        System.err.println("Chdir: " + cstring(addr) + " -> " + path + " pwd: " + cwd);
-        if(gd.stat(this,path).type() != FStat.S_IFDIR) return -ENOTDIR;
+        //System.err.println("Chdir: " + cstring(addr) + " -> " + path + " pwd: " + cwd);
+        if(gs.stat(this,path).type() != FStat.S_IFDIR) return -ENOTDIR;
         cwd = path;
-        System.err.println("Now: [" + cwd + "]");
+        //System.err.println("Now: [" + cwd + "]");
         return 0;
     }
     
@@ -439,6 +525,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         protected static final int STAT = 2;
         protected static final int LSTAT = 3;
         protected static final int MKDIR = 4;
+        protected static final int UNLINK = 5;
         
         final UnixRuntime[] tasks;
         int nextPID = 1;
@@ -451,7 +538,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public GlobalState(int maxProcs, boolean defaultMounts) {
             tasks = new UnixRuntime[maxProcs+1];
             if(defaultMounts) {
-            	    addMount("/",new HostFS());
+                addMount("/",new HostFS());
                 addMount("/dev",new DevFS());
             }
         }
@@ -503,13 +590,13 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public synchronized void removeMount(String path) {
             if(!path.startsWith("/")) throw new IllegalArgumentException("Mount point doesn't start with a /");
             if(path.equals("/")) {
-            	    removeMount(-1);
+                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 Error("mount point doesn't exist");
-               removeMount(p);
+                if(p == mps.length) throw new IllegalArgumentException("mount point doesn't exist");
+                removeMount(p);
             }
         }
         
@@ -524,13 +611,13 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         private Object fsop(int op, UnixRuntime r, String normalizedPath, int arg1, int arg2) throws ErrnoException {
             int pl = normalizedPath.length();
             if(pl != 0) {
-            	    MP[] list;
+                MP[] list;
                 synchronized(this) { list = mps; }
                 for(int i=0;i<list.length;i++) {
-                	    MP mp = list[i];
-                	    int mpl = mp.path.length();
+                    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);
+                        return dispatch(mp.fs,op,r,pl == mpl ? "" : normalizedPath.substring(mpl+1),arg1,arg2);
                 }
             }
             return dispatch(root,op,r,normalizedPath,arg1,arg2);
@@ -538,10 +625,11 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         
         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 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");
             }
         }
@@ -550,6 +638,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         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); }
         
         private Hashtable execCache = new Hashtable();
         private static class CacheEnt {
@@ -560,15 +649,18 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         }
 
         public synchronized Object exec(UnixRuntime r, String path) throws ErrnoException {
+            // FIXME: Hideous hack to make a standalone busybox possible
+            if(path.equals("bin/busybox") && r.getClass().getName().endsWith("BusyBox"))
+                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");
+                //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);
@@ -582,7 +674,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             
             try {
                 int n = s.read(buf,0,buf.length);
-                if(n == -1) throw new Error("zero length file");
+                if(n == -1) throw new ErrnoException(ENOEXEC);
                 
                 switch(buf[0]) {
                     case '\177': // possible ELF
@@ -591,7 +683,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                         break;
                     case '#':
                         if(n == 1) {
-                        	    int n2 = s.read(buf,1,buf.length-1);
+                            int n2 = s.read(buf,1,buf.length-1);
                             if(n2 == -1) throw new ErrnoException(ENOEXEC);
                             n += n2;
                         }
@@ -599,7 +691,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                         int p = 2;
                         n -= 2;
                         OUTER: for(;;) {
-                        	    for(int i=p;i<p+n;i++) if(buf[i] == '\n') { p = i; break OUTER; }
+                            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);
@@ -609,36 +701,38 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                         for(arg=2;arg<p;arg++) if(buf[arg] == ' ') break;
                         if(arg < p) {
                             int cmdEnd = arg;
-                        	    while(arg < p && buf[arg] == ' ') 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);
+                            command[0] = new String(buf,2,p-2);
                         }
-                        System.err.println("command[0]: " + command[0] + " command[1]: " + command[1]);
+                        //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);
+                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);
+                    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) {
-                	    throw new ErrnoException(EIO);
+                    if(STDERR_DIAG) e.printStackTrace();
+                    throw new ErrnoException(EIO);
                 }
             } else {
-            	    ent = new CacheEnt(mtime,size,command);
+                ent = new CacheEnt(mtime,size,command);
             }
             
             fd.close();
@@ -659,6 +753,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         // 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;
     }
         
     // FEATURE: chroot support in here
@@ -676,15 +771,15 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         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++;
+            if(inp != 0 || cwdl==0) {
+                if(in[inp] != '/') { out[outp++] = in[inp++]; continue; }
+                while(in[inp] == '/') inp++;
             }
             if(in[inp] == '\0') continue;
             if(in[inp] != '.') { out[outp++] = '/'; out[outp++] = in[inp++]; continue; }
@@ -693,7 +788,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                 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;
             }
             inp++;
@@ -730,13 +825,19 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
     
     public static class HostFS extends FS {
-        InodeCache inodes = new InodeCache(4096);
+        InodeCache inodes = new InodeCache(4000);
         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;
@@ -747,7 +848,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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] = '/';
                 }
@@ -766,6 +867,13 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             return r.hostFSOpen(f,flags,mode,this);
         }
         
+        public void unlink(UnixRuntime r, String path) throws ErrnoException {
+            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);
+        }
+        
         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);
@@ -822,9 +930,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             int reclen;
             OUTER: for(;len > 0 && pos < size();pos++){
                 switch(pos) {
-                	    case -2:
+                    case -2:
                     case -1:
-                	    	    ino = pos == -1 ? parentInode() : myInode();
+                        ino = pos == -1 ? parentInode() : myInode();
                         if(ino == -1) continue;
                         reclen = 9 + (pos == -1 ? 2 : 1);
                         if(reclen > len) break OUTER;
@@ -938,7 +1046,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                     
                     public String name(int n) {
                         switch(n) {
-                        	    case 0: return "null";
+                            case 0: return "null";
                             case 1: return "zero";
                             case 2: return "fd";
                             default: return null;
@@ -970,6 +1078,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             return null;
         }
         
-        public void mkdir(UnixRuntime r, String path, int mode) throws ErrnoException { 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); }
+    }    
 }