1 /* java.lang.VMThrowable -- VM support methods for Throwable. 2 Copyright (C) 1998, 1999, 2002 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 19 02111-1307 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 package java.lang; 39 40 import gnu.gcj.runtime.NameFinder; 41 import gnu.gcj.runtime.StackTrace; 42 43 /** 44 * VM dependent state and support methods Throwable. 45 * It is deliberately package local and final and should only be accessed 46 * by the Throwable class. 47 * <p> 48 * This is the version used by libgcj (http://gcc.gnu.org/java/). 49 * 50 * @author Mark Wielaard (mark@klomp.org) 51 */ 52 final class VMThrowable 53 { 54 private gnu.gcj.runtime.StackTrace trace; 55 56 /** 57 * Private contructor, create VMThrowables with fillInStackTrace(); 58 */ VMThrowable()59 private VMThrowable() { } 60 61 /** 62 * Fill in the stack trace with the current execution stack. 63 * Called by <code>Throwable.fillInStackTrace()</code> to get the state of 64 * the VM. Can return null when the VM does not support caputing the VM 65 * execution state. 66 * 67 * @return a new VMThrowable containing the current execution stack trace. 68 * @see Throwable#fillInStackTrace() 69 */ fillInStackTrace(Throwable t)70 static VMThrowable fillInStackTrace(Throwable t) 71 { 72 VMThrowable state = null; 73 74 /* FIXME: size of the stack trace is limited to 128 elements. 75 It's undoubtedly sensible to limit the stack trace, but 128 is 76 rather arbitrary. It may be better to configure this. */ 77 if (trace_enabled) 78 { 79 state = new VMThrowable (); 80 state.trace = new gnu.gcj.runtime.StackTrace(128); 81 } 82 return state; 83 } 84 85 /** 86 * Returns an <code>StackTraceElement</code> array based on the execution 87 * state of the VM as captured by <code>fillInStackTrace</code>. 88 * Called by <code>Throwable.getStackTrace()</code>. 89 * 90 * @return a non-null but possible zero length array of StackTraceElement. 91 * @see Throwable#getStackTrace() 92 */ getStackTrace(Throwable t)93 StackTraceElement[] getStackTrace(Throwable t) 94 { 95 StackTraceElement[] result; 96 if (trace != null) 97 { 98 NameFinder nameFinder = new NameFinder(); 99 result = nameFinder.lookup(t, trace.stackTraceAddrs(), 100 trace.length()); 101 nameFinder.close(); 102 } 103 else 104 result = new StackTraceElement[0]; 105 106 return result; 107 } 108 109 // Setting this flag to false prevents fillInStackTrace() from running. 110 static boolean trace_enabled = true; 111 } 112