sketch of Runtime.exec() and Calendar; misc bugfixes

classpath/java/lang/Runtime.java

@@ -1,5 +1,11 @@
 package java.lang;
 
+import java.io.InputStream;
+import java.io.FileInputStream;
+import java.io.OutputStream;
+import java.io.FileOutputStream;
+import java.io.FileDescriptor;
+
 public class Runtime {
   private static final Runtime instance = new Runtime();
 
@@ -25,6 +31,26 @@ public class Runtime {
     }
   }
 
+  public Process exec(String command) {
+    int[] process = new int[4];
+    exec(command, process);
+    return new MyProcess(process[0], process[1], process[2], process[3]);
+  }
+
+  public Process exec(String[] command) {
+    int[] process = new int[4];
+    exec(command, process);
+    return new MyProcess(process[0], process[1], process[2], process[3]);
+  }
+
+  private static native void exec(String command, int[] process);
+
+  private static native void exec(String[] command, int[] process);
+
+  private static native int exitValue(int pid);
+
+  private static native int waitFor(int pid);
+
   private static native void load(String name, boolean mapName);
 
   public native void gc();
@@ -32,4 +58,50 @@ public class Runtime {
   public native void exit(int code);
 
   public native long freeMemory();
+
+  private static class MyProcess extends Process {
+    private int pid;
+    private final int in;
+    private final int out;
+    private final int err;
+    private int exitCode;
+
+    public MyProcess(int pid, int in, int out, int err) {
+      this.pid = pid;
+      this.in = in;
+      this.out = out;
+      this.err = err;
+    }
+
+    public void destroy() {
+      throw new RuntimeException("not implemented");
+    }
+
+    public int exitValue() {
+      if (pid != 0) {
+        exitCode = Runtime.exitValue(pid);
+      }
+      return exitCode;
+    }
+
+    public InputStream getInputStream() {
+      return new FileInputStream(new FileDescriptor(in));
+    }
+
+    public OutputStream getOutputStream() {
+      return new FileOutputStream(new FileDescriptor(out));
+    }
+
+    public InputStream getErrorStream() {
+      return new FileInputStream(new FileDescriptor(err));
+    }
+
+    public int waitFor() throws InterruptedException {
+      if (pid != 0) {
+        exitCode = Runtime.waitFor(pid);
+        pid = 0;
+      }
+      return exitCode;
+    }
+  }
 }