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diff --git a/libjava/gnu/gcj/runtime/NameFinder.java b/libjava/gnu/gcj/runtime/NameFinder.java
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+++ b/libjava/gnu/gcj/runtime/NameFinder.java
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+/* NameFinder.java -- Translates addresses to StackTraceElements.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+
+   This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
+details.  */
+
+package gnu.gcj.runtime;
+
+import gnu.gcj.RawData;
+
+import java.lang.StringBuffer;
+
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.IOException;
+import java.io.File;
+
+/**
+ * Helper class that translates addresses (represented as longs) to a
+ * StackTraceElement array.
+ *
+ * There are a couple of system properties that can be set to manipulate the
+ * result (all default to true):
+ * <li>
+ * <ul><code>gnu.gcj.runtime.NameFinder.demangle</code>
+ *     Whether names should be demangled.</ul>
+ * <ul><code>gnu.gcj.runtime.NameFinder.sanitize</code></ul>
+ *     Whether calls to initialize exceptions and starting the runtime system
+ *     should be removed from the stack trace. Only done when names are
+ *     demangled.</ul>
+ * <ul><code>gnu.gcj.runtime.NameFinder.remove_unknown</code>
+ *     Wheter calls to unknown functions (class and method names are unknown)
+ *     should be removed from the stack trace. Only done when the stack is
+ *     sanitized.</ul>
+ * <ul><code>gnu.gcj.runtime.NameFinder.use_addr2line</code>
+ *     Wheter an external process (addr2line or addr2name.awk) should be used
+ *     as fallback to convert the addresses to function names when the runtime
+ *     is unable to do it through <code>dladdr</code>.</ul>
+ * </li>
+ *
+ * <code>close()</code> should be called to get rid of all resources.
+ *
+ * This class is used from <code>java.lang.VMThrowable</code>.
+ *
+ * Currently the <code>lookup(long[])</code> method is not thread safe.
+ * It can easily be made thread safe by synchronizing access to all external
+ * processes when used.
+ *   
+ * @author Mark Wielaard (mark@klomp.org)
+ */
+public class NameFinder
+{
+  // Set these to false when not needed.
+  private static final boolean demangle
+	  = Boolean.valueOf(System.getProperty
+		("gnu.gcj.runtime.NameFinder.demangle", "true")
+	    ).booleanValue();
+  private static final boolean sanitize
+	  = Boolean.valueOf(System.getProperty
+		("gnu.gcj.runtime.NameFinder.sanitize", "true")
+	    ).booleanValue();
+  private static final boolean remove_unknown
+	  = Boolean.valueOf(System.getProperty
+		("gnu.gcj.runtime.NameFinder.remove_unknown", "true")
+	    ).booleanValue();
+  private static final boolean use_addr2line
+	  = Boolean.valueOf(System.getProperty
+		("gnu.gcj.runtime.NameFinder.use_addr2line", "true")
+	    ).booleanValue();
+
+  /**
+   * The name of the currently running executable.
+   */
+  private final String executable;
+
+  /**
+   * Process used for demangling names.
+   */
+  private Process cppfilt;
+
+  private BufferedWriter cppfiltOut;
+  private BufferedReader cppfiltIn;
+
+  /**
+   * Process used for translating addresses to function/file names.
+   */
+  private Process addr2line;
+
+  private BufferedWriter addr2lineOut;
+  private BufferedReader addr2lineIn;
+
+  /**
+   * Creates a new NameFinder. Call close to get rid of any resources
+   * created while using the <code>lookup</code> methods.
+   */
+  public NameFinder()
+  {
+    executable = getExecutable();
+    Runtime runtime = Runtime.getRuntime();
+    if (demangle)
+    {
+      try
+	{
+	  String[] exec = new String[] {"c++filt", "-s", "java"};
+	  cppfilt = runtime.exec(exec);
+	  cppfiltIn = new BufferedReader
+			(new InputStreamReader(cppfilt.getInputStream()));
+	  cppfiltOut = new BufferedWriter
+			(new OutputStreamWriter(cppfilt.getOutputStream()));
+	}
+      catch (IOException ioe)
+        {
+	  if (cppfilt != null)
+	    cppfilt.destroy();
+	  cppfilt = null;
+	}
+    }
+
+    if (use_addr2line)
+      {
+	try
+	  {
+	    String[] exec = new String[] {"addr2line", "-f", "-e", executable};
+	    addr2line = runtime.exec(exec);
+	  }
+	catch (IOException ioe)
+	  {
+	    try
+	      {
+		String[] exec = new String[] {"addr2name.awk", executable};
+		addr2line = runtime.exec(exec);
+	      }
+	    catch (IOException ioe2) { addr2line = null; }
+	  }
+
+	if (addr2line != null)
+	  {
+	    try
+	      {
+		addr2lineIn = new BufferedReader
+			(new InputStreamReader(addr2line.getInputStream()));
+		addr2lineOut = new BufferedWriter
+			(new OutputStreamWriter(addr2line.getOutputStream()));
+	      }
+	    catch (IOException ioe)
+	      {  
+		addr2line.destroy();
+		addr2line = null;
+	      }
+	  }
+      }
+  }
+
+  /**
+   * Returns the name of the currently running process.
+   */
+  native private static String getExecutable();
+
+  /**
+   * Tries to use dladdr to create the nth StackTraceElement from the given
+   * addresses. Returns null on failure.
+   */
+  native private StackTraceElement dladdrLookup(RawData addrs, int n);
+
+  /**
+   * Returns the nth element from the stack as a hex encoded String.
+   */
+  native private String getAddrAsString(RawData addrs, int n);
+
+  /**
+   * Creates the nth StackTraceElement from the given native stacktrace.
+   */
+  private StackTraceElement lookup(RawData addrs, int n)
+  {
+    StackTraceElement result;
+
+    result = dladdrLookup(addrs, n);
+    if (result == null)
+      {
+	String name = null;
+	String file = null;
+	String hex = getAddrAsString(addrs, n);
+	
+	if (addr2line != null)
+	  {
+	    try
+	      {
+		addr2lineOut.write(hex);
+		addr2lineOut.newLine();
+		addr2lineOut.flush();
+		name = addr2lineIn.readLine();
+		file = addr2lineIn.readLine();
+	      }
+	    catch (IOException ioe) { addr2line = null; }
+	  }
+
+	if (name == null || "??".equals(name))
+	  name = hex;
+
+	result = createStackTraceElement(name, file);
+      }
+
+    return result;
+  }
+
+  /**
+   * Given an Throwable and a native stacktrace returns an array of
+   * StackTraceElement containing class, method, file and linenumbers.
+   */
+  public StackTraceElement[] lookup(Throwable t, RawData addrs, int length)
+  {
+    StackTraceElement[] elements = new StackTraceElement[length];
+    for (int i=0; i < length; i++)
+      elements[i] = lookup(addrs, i);
+
+    if (demangle && sanitize)
+      return sanitizeStack(elements, t);
+    else
+      return elements;
+  }
+
+  
+  /**
+   * Removes calls to initialize exceptions and the runtime system from
+   * the stack trace including stack frames of which nothing usefull is known.
+   * Throw away the top of the stack till we find the constructor(s)
+   * of this Throwable or at least the contructors of java.lang.Throwable
+   * or the actual fillInStackTrace call.
+   * Also throw away from the top everything before and including a runtime
+   * _Jv_Throw call.
+   */
+  private static StackTraceElement[] sanitizeStack(StackTraceElement[] elements,
+						   Throwable t)
+  {
+    StackTraceElement[] stack;
+
+    String className = t.getClass().getName();
+    String consName;
+    int lastDot = className.lastIndexOf('.');
+    if (lastDot == -1)
+      consName = className + '(';
+    else
+      consName = className.substring(lastDot + 1) + '(';
+
+    int unknown = 0;
+    int last_throw = -1;
+    int length = elements.length;
+    int end = length-1;
+    for (int i = 0; i < length; i++)
+      {
+	String CName = elements[i].getClassName();
+	String MName = elements[i].getMethodName();
+	if ((CName == null && MName != null && MName.startsWith("_Jv_Throw"))
+	  ||
+	   (CName != null
+	    && (CName.equals(className)
+		|| CName.equals("java.lang.Throwable")
+		|| CName.equals("java.lang.VMThrowable"))
+	    && MName != null
+	    && (MName.startsWith(consName)
+		|| MName.startsWith("Throwable(")
+		|| MName.startsWith("fillInStackTrace("))))
+	  last_throw = i;
+	else if (remove_unknown && CName == null 
+		 && (MName == null || MName.startsWith("0x")))
+	  unknown++;
+	else if ("main(java.lang.String[])".equals(MName))
+	  {
+	    end = i;
+	    break;
+	  }
+      }
+    int begin = last_throw+1;
+
+    // Now filter out everything at the start and the end that is not part
+    // of the "normal" user program including any elements that have no
+    // usefull information whatsoever unless that means we filter out all info.
+    int nr_elements = end-begin-unknown+1;
+    if ((begin > 0 || end < length-1 || unknown > 0) && nr_elements > 0)
+      {
+	stack = new StackTraceElement[nr_elements];
+	int pos =0;
+	for (int i=begin; i<=end; i++)
+	  {
+	    String MName;
+	    if (unknown == 0
+		|| !(elements[i].getClassName() == null
+		     && ((MName = elements[i].getMethodName()) == null
+			 || MName.startsWith("0x"))))
+	      {
+		stack[pos] = elements[i];
+		pos++;
+	      }
+	  }
+      }
+    else
+      stack = elements;
+
+    return stack;
+  }
+
+  /**
+   * Creates a StackTraceElement given a string and a filename.
+   * Splits the given string into the class and method part.
+   * The string name will be a demangled to a fully qualified java method
+   * string. The string file will be decomposed into a file name and possibly
+   * a line number. The name should never be null, but the file may be if it
+   * is unknown.
+   */
+  private StackTraceElement createStackTraceElement(String name, String file)
+  {
+    if (!demangle)
+      return new StackTraceElement(file, -1, null, name, false);
+
+    String s = demangleName(name);
+    String methodName = s;
+    String className = null;
+    int bracket = s.indexOf('(');
+    if (bracket > 0)
+      {
+	int dot = s.lastIndexOf('.', bracket);
+	if (dot > 0)
+	  {
+	    className = s.substring(0, dot);
+	    methodName = s.substring(dot+1, s.length());
+	  }
+      }
+
+    String fileName = file;
+    int line = -1;
+    if (fileName != null)
+      {
+	int colon = file.indexOf(':');
+	if (colon > 0)
+	  {
+	    fileName = file.substring(0, colon);
+	    try
+	      {
+		line = Integer.parseInt(file.substring(colon+1, file.length()));
+	      }
+	    catch (NumberFormatException nfe) { /* ignore */ }
+	  }
+
+	if (line == 0)
+	  line =-1;
+
+	if ("".equals(fileName) || "??".equals(fileName))
+	  fileName = null;
+	else if (fileName != null)
+	  {
+	    try
+	      {
+		fileName = new File(fileName).getCanonicalPath();
+	      }
+	    catch (IOException ioe) { /* ignore */ }
+	  }
+      }
+
+    return new StackTraceElement(fileName, line, className, methodName, false);
+  }
+
+  /**
+   * Demangles the given String if possible. Returns the demangled String or
+   * the original string if demangling is impossible.
+   */
+  private String demangleName(String s)
+  {
+    if (cppfilt != null)
+    {
+      try
+	{
+	  cppfiltOut.write(s);
+	  cppfiltOut.newLine();
+	  cppfiltOut.flush();
+	  return cppfiltIn.readLine();
+	}
+      catch (IOException ioe) { cppfilt.destroy(); cppfilt = null; }
+    }
+
+    return s;
+  }
+
+  /**
+   * Releases all resources used by this NameFinder.
+   */
+  public void close()
+  {
+    if (cppfilt != null)
+      cppfilt.destroy();
+
+    if (addr2line != null)
+      addr2line.destroy();
+  }
+
+  /**
+   * Calls close to get rid of all resources.
+   */
+  protected void finalize()
+  {
+    close();
+  }
+}