X-Git-Url: http://git.megacz.com/?p=nestedvm.git;a=blobdiff_plain;f=src%2Forg%2Fibex%2Fnestedvm%2FUnixRuntime.java;h=306b70e5a4b09bfe2388ec0633f194d0049314bc;hp=f156603af8ac180900fe074b1e7932947e3d1eff;hb=b11e7c6c29f2b5f7b0828bf93eb741c4a30ec411;hpb=6b824fa9a85f2f58fcb938ea5924df0c73cea43c

diff --git a/src/org/ibex/nestedvm/UnixRuntime.java b/src/org/ibex/nestedvm/UnixRuntime.java
index f156603..306b70e 100644
--- a/src/org/ibex/nestedvm/UnixRuntime.java
+++ b/src/org/ibex/nestedvm/UnixRuntime.java
@@ -1,12 +1,10 @@
 // Copyright 2000-2005 the Contributors, as shown in the revision logs.
-// Licensed under the Apache Public Source License 2.0 ("the License").
+// 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.*;
-// HACK: This is ugly, this stuff needs to be in org.ibex.util or something
-import org.ibex.classgen.util.Sort;
 import java.io.*;
 import java.util.*;
 import java.net.*;
@@ -46,28 +44,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         if(!exec) {
             gs = defaultGS;
             String userdir = Platform.getProperty("user.dir");
-            String nvroot = Platform.getProperty("nestedvm.root");
-            cwd = "";
-            if(userdir != null && nvroot == null) {
-                if(userdir.startsWith("/") && File.separatorChar == '/') {
-                    cwd = userdir.substring(1);
-                } else {
-                    Vector vec = new Vector();
-                    File root = HostFS.hostRootDir();
-                    String s = new File(userdir).getAbsolutePath();
-                    File d = new File(s);
-                    System.err.println(s);
-                    System.err.println(d);
-                    while(!d.equals(root)) {
-                        System.err.println("Got " + d.getName());
-                        vec.addElement(d.getName());
-                        if((s = d.getParent()) == null) break;
-                        d = new File(s);
-                    }
-                    if(s != null)
-                        for(int i=vec.size()-1;i>=0;i--) cwd += (String) vec.elementAt(i) + (i==0?"":"/");
-                }
-            }
+            cwd = userdir == null ? null : gs.mapHostPath(userdir);
+            if(cwd == null) cwd = "/";
+            cwd = cwd.substring(1);
         }
     }
     
@@ -93,13 +72,16 @@ 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];
+        String tmp;
         if(!envHas("USER",extra) && Platform.getProperty("user.name") != null)
             defaults[n++] = "USER=" + Platform.getProperty("user.name");
-        if(!envHas("HOME",extra) && Platform.getProperty("user.home") != null)
-            defaults[n++] = "HOME=" + Platform.getProperty("user.home");
+        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) && !win32Hacks)  defaults[n++] = "TERM=vt100";
         if(!envHas("TZ",extra))    defaults[n++] = "TZ=" + posixTZ();
@@ -169,23 +151,51 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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) {
+    private int sys_access(int cstring, int mode) throws ErrnoException, ReadFaultException {
         // FEATURE: sys_access
-        return 0;
+        return gs.stat(this,cstring(cstring)) == null ? -ENOENT : 0;
     }
     
     private int sys_realpath(int inAddr, int outAddr) throws FaultException {
@@ -387,7 +397,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     static {
         Method m;
         try {
-            m = Class.forName("org.ibex.nestedvm.RuntimeCompiler").getMethod("compile",new Class[]{Seekable.class,String.class});
+            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) {
@@ -396,14 +406,14 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         runtimeCompilerCompile = m;
     }
             
-    public Class runtimeCompile(Seekable s) throws IOException {
+    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;
         }
         
         try {
-            return (Class) runtimeCompilerCompile.invoke(null,new Object[]{s,"unixruntime"});
+            return (Class) runtimeCompilerCompile.invoke(null,new Object[]{s,"unixruntime,maxinsnpermethod=256,lessconstants",sourceName});
         } catch(IllegalAccessException e) {
             e.printStackTrace();
             return null;
@@ -463,7 +473,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                     if(n < 4) s.tryReadFully(buf,n,4-n);
                     if(buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F') return -ENOEXEC;
                     s.seek(0);
-                    Class c = runtimeCompile(s);
+                    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);
@@ -482,13 +494,16 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
                         if(p == buf.length) break OUTER;
                         n = s.read(buf,p,buf.length-p);
                     }
-                    int arg;
-                    for(arg=2;arg<p;arg++) if(buf[arg] == ' ') break;
-                    int cmdEnd = arg;
-                    while(arg < p && buf[arg] == ' ') arg++;
+                    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,2,cmdEnd),
-                        arg < p ? new String(buf,arg,p-arg) : null
+                        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);
@@ -503,13 +518,16 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
     }
     
     public int execScript(String path, String[] command, String[] argv, String[] envp) throws ErrnoException {
-        String[] newArgv = new String[argv.length + command[1] != null ? 2 : 1];
+        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);
-        p = 1;
+        newArgv[1] = "/" + path;
+        p = 2;
         if(command[1] != null) newArgv[p++] = command[1];
-        newArgv[p++] = "/" + path;
         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);
     }
     
@@ -687,7 +705,170 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         copyout(buf,addr,n);
         return n;
     }
-    
+
+    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;
@@ -1146,6 +1327,9 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         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;
         
@@ -1154,9 +1338,62 @@ 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());
+            }
+        }
+        
+        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 {
@@ -1223,7 +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) {
@@ -1284,7 +1521,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         public abstract void unlink(UnixRuntime r, String path) throws ErrnoException;
     }
         
-    // chroot support should go in here if it is ever implemented chroot support in here
+    // chroot support should go in here if it is ever implemented
     private String normalizePath(String path) {
         boolean absolute = path.startsWith("/");
         int cwdl = cwd.length();
@@ -1295,6 +1532,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         
         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) {
@@ -1304,7 +1542,6 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             outp = cwdl;
         }
 
-        path.getChars(0,path.length(),in,0);
         while(in[inp] != 0) {
             if(inp != 0) {
                 while(in[inp] != 0 && in[inp] != '/') { out[outp++] = in[inp++]; }
@@ -1332,7 +1569,8 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         }
         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) {
@@ -1364,23 +1602,7 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         protected File root;
         public File getRoot() { return root; }
         
-        static File hostRootDir() {
-            if(Platform.getProperty("nestedvm.root") != null) {
-                File f = new File(Platform.getProperty("nestedvm.root"));
-                if(f.isDirectory()) return f;
-                // fall through to case below
-            }
-            String cwd = Platform.getProperty("user.dir");
-            File f = new File(cwd != null ? cwd : ".");
-            if(!f.exists()) throw new Error("Couldn't get File for cwd");
-            f = new File(f.getAbsolutePath());
-            while(f.getParent() != null) f = new File(f.getParent());
-            // This works around a bug in some versions of ClassPath
-            if(f.getPath().length() == 0) f = new File("/");
-            return f;
-        }
-        
-        private File hostFile(String path) {
+        protected File hostFile(String path) {
             char sep = File.separatorChar;
             if(sep != '/') {
                 char buf[] = path.toCharArray();
@@ -1394,11 +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);
@@ -1408,7 +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 {
@@ -1454,6 +1688,23 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
             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);
@@ -1631,5 +1882,55 @@ public abstract class UnixRuntime extends Runtime implements Cloneable {
         
         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); }
+        }
+    }
 }