From 3fe197c6e72549b8a58b4fe78d46b98ea30ab3f5 Mon Sep 17 00:00:00 2001 From: Magesh Umasankar Date: Fri, 18 Jan 2002 15:26:50 +0000 Subject: [PATCH] Modified the hack to initialize a class such that the side effect of having to create a valid object is not there anymore. PR: 4107 git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@270780 13f79535-47bb-0310-9956-ffa450edef68 --- WHATSNEW | 2 + .../org/apache/tools/ant/AntClassLoader.java | 193 ++++++++++-------- 2 files changed, 108 insertions(+), 87 deletions(-) diff --git a/WHATSNEW b/WHATSNEW index 69f73da29..9db3402cd 100644 --- a/WHATSNEW +++ b/WHATSNEW @@ -31,6 +31,8 @@ Changes that could break older environments: Fixed bugs: ----------- +* Fixed bug where used to sometimes invoke class constructors twice. + * Fixed bug with 4NT shell support * Fixed bug where ant would not perform ftp without remotedir being diff --git a/src/main/org/apache/tools/ant/AntClassLoader.java b/src/main/org/apache/tools/ant/AntClassLoader.java index d46c62426..16fe138b3 100644 --- a/src/main/org/apache/tools/ant/AntClassLoader.java +++ b/src/main/org/apache/tools/ant/AntClassLoader.java @@ -54,6 +54,7 @@ package org.apache.tools.ant; +import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.lang.reflect.InvocationTargetException; import java.util.Enumeration; @@ -78,6 +79,7 @@ import org.apache.tools.ant.types.Path; * * @author Conor MacNeill * @author Jesse Glick + * @author Magesh Umasankar */ public class AntClassLoader extends ClassLoader implements BuildListener { @@ -155,8 +157,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener { URL url = null; while ((pathElementsIndex < pathComponents.size()) && (url == null)) { - try { - File pathComponent + try { + File pathComponent = (File)pathComponents.elementAt(pathElementsIndex); url = getResourceURL(pathComponent, this.resourceName); pathElementsIndex++; @@ -173,20 +175,20 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * The size of buffers to be used in this classloader. */ private final static int BUFFER_SIZE = 8192; - + /** * The components of the classpath that the classloader searches for classes */ Vector pathComponents = new Vector(); - + /** * The project to which this class loader belongs. */ private Project project; /** - * Indicates whether the parent class loader should be - * consulted before trying to load with this class loader. + * Indicates whether the parent class loader should be + * consulted before trying to load with this class loader. */ private boolean parentFirst = true; @@ -195,20 +197,20 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * regardless of whether the parent class loader is being searched first or not. */ private Vector systemPackages = new Vector(); - + /** * These are the package roots that are to be loaded by this class loader * regardless of whether the parent class loader is being searched first or not. */ private Vector loaderPackages = new Vector(); - + /** * This flag indicates that the classloader will ignore the base * classloader if it can't find a class. */ private boolean ignoreBase = false; - /** + /** * The parent class loader, if one is given or can be determined */ private ClassLoader parent = null; @@ -216,14 +218,14 @@ public class AntClassLoader extends ClassLoader implements BuildListener { /** * A hashtable of zip files opened by the classloader */ - private Hashtable zipFiles = new Hashtable(); - + private Hashtable zipFiles = new Hashtable(); + /** * The context loader saved when setting the thread's current context loader. */ private ClassLoader savedContextLoader = null; private boolean isContextLoaderSaved = false; - + private static Method getProtectionDomain = null; private static Method defineClassProtectionDomain = null; private static Method getContextClassLoader = null; @@ -234,7 +236,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { Class protectionDomain = Class.forName("java.security.ProtectionDomain"); Class[] args = new Class[] {String.class, byte[].class, Integer.TYPE, Integer.TYPE, protectionDomain}; defineClassProtectionDomain = ClassLoader.class.getDeclaredMethod("defineClass", args); - + getContextClassLoader = Thread.class.getMethod("getContextClassLoader", new Class[0]); args = new Class[] {ClassLoader.class}; setContextClassLoader = Thread.class.getMethod("setContextClassLoader", args); @@ -242,7 +244,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { catch (Exception e) {} } - + /** * Create a classloader for the given project using the classpath given. * @@ -268,7 +270,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } } } - + /** * Create a classloader for the given project using the classpath given. * @@ -279,7 +281,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * @param parentFirst if true indicates that the parent classloader should be consulted * before trying to load the a class through this loader. */ - public AntClassLoader(ClassLoader parent, Project project, Path classpath, + public AntClassLoader(ClassLoader parent, Project project, Path classpath, boolean parentFirst) { this(project, classpath); if (parent != null) { @@ -322,7 +324,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { project = null; this.parentFirst = parentFirst; } - + /** * Log a message through the project object if one has been provided. * @@ -348,7 +350,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } if (getContextClassLoader != null && setContextClassLoader != null) { try { - savedContextLoader + savedContextLoader = (ClassLoader)getContextClassLoader.invoke(Thread.currentThread(), new Object[0]); Object[] args = new Object[] {this}; setContextClassLoader.invoke(Thread.currentThread(), args); @@ -363,7 +365,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } } } - + /** * Reset the current thread's context loader to its original value */ @@ -385,19 +387,19 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } } } - - + + /** * Add an element to the classpath to be searched * */ public void addPathElement(String pathElement) throws BuildException { - File pathComponent + File pathComponent = project != null ? project.resolveFile(pathElement) : new File(pathElement); pathComponents.addElement(pathComponent); } - + /** * The CLASSPATH this classloader will consult. */ @@ -426,23 +428,40 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } /** - * Force initialization of a class in a JDK 1.1 compatible, albeit hacky - * way + * Force initialization of a class in a JDK 1.1 compatible, albeit hacky + * way */ public static void initializeClass(Class theClass) { - // ***HACK*** We try to create an instance to force the VM to run the - // class' static initializer. We don't care if the instance can't - // be created - we are just interested in the side effect. - try { - theClass.newInstance(); - } - catch (Throwable t) { - //ignore - our work is done + // ***HACK*** We ask the VM to create an instance + // by voluntarily providing illegal arguments to force + // the VM to run the class' static initializer, while + // at the same time not running a valid constructor. + + final Constructor[] cons = theClass.getDeclaredConstructors(); + //At least one constructor is guaranteed to be there, but check anyway. + if (cons != null) { + if (cons.length > 0 && cons[0] != null) { + final String[] strs = new String[1024]; + try { + cons[0].newInstance(strs); + // Expecting an exception to be thrown by this call: + // IllegalArgumentException: wrong number of Arguments + } catch (Throwable t) { + // Ignore - we are interested only in the side + // effect - that of getting the static initializers + // invoked. As we do not want to call a valid + // constructor to get this side effect, an + // attempt is made to call a hopefully + // invalid constructor - come on, nobody + // would have a constructor that takes in + // 1024 String arguments ;-) + } + } } } - + /** - * Add a package root to the list of packages which must be loaded on the + * Add a package root to the list of packages which must be loaded on the * parent loader. * * All subpackages are also included. @@ -452,7 +471,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { public void addSystemPackageRoot(String packageRoot) { systemPackages.addElement(packageRoot + "."); } - + /** * Add a package root to the list of packages which must be loaded using * this loader. @@ -464,7 +483,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { public void addLoaderPackageRoot(String packageRoot) { loaderPackages.addElement(packageRoot + "."); } - + /** @@ -475,7 +494,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * classloader. * * @param classname the classname to be loaded. - * + * * @return the required Class object * * @throws ClassNotFoundException if the requested class does not exist on @@ -483,13 +502,13 @@ public class AntClassLoader extends ClassLoader implements BuildListener { */ public Class forceLoadClass(String classname) throws ClassNotFoundException { log("force loading " + classname, Project.MSG_DEBUG); - + Class theClass = findLoadedClass(classname); if (theClass == null) { theClass = findClass(classname); } - + return theClass; } @@ -500,7 +519,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * which have already been loaded on the parent loader. * * @param classname the classname to be loaded. - * + * * @return the required Class object * * @throws ClassNotFoundException if the requested class does not exist on @@ -508,13 +527,13 @@ public class AntClassLoader extends ClassLoader implements BuildListener { */ public Class forceLoadSystemClass(String classname) throws ClassNotFoundException { log("force system loading " + classname, Project.MSG_DEBUG); - + Class theClass = findLoadedClass(classname); if (theClass == null) { theClass = findBaseClass(classname); } - + return theClass; } @@ -557,17 +576,17 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } } } - + if (resourceStream == null) { - log("Couldn't load ResourceStream for " + name, + log("Couldn't load ResourceStream for " + name, Project.MSG_DEBUG); } return resourceStream; } - - - + + + /** * Get a stream to read the requested resource name from this loader. * @@ -577,10 +596,10 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * found on the loader's classpath. */ private InputStream loadResource(String name) { - // we need to search the components of the path to see if we can find the - // class we want. + // we need to search the components of the path to see if we can find the + // class we want. InputStream stream = null; - + for (Enumeration e = pathComponents.elements(); e.hasMoreElements() && stream == null; ) { File pathComponent = (File)e.nextElement(); stream = getResourceStream(pathComponent, name); @@ -615,11 +634,11 @@ public class AntClassLoader extends ClassLoader implements BuildListener { if (!file.exists()) { return null; } - + if (file.isDirectory()) { - File resource = new File(file, resourceName); - - if (resource.exists()) { + File resource = new File(file, resourceName); + + if (resource.exists()) { return new FileInputStream(resource); } } @@ -628,7 +647,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { ZipFile zipFile = (ZipFile)zipFiles.get(file); if (zipFile == null) { zipFile = new ZipFile(file); - zipFiles.put(file, zipFile); + zipFiles.put(file, zipFile); } ZipEntry entry = zipFile.getEntry(resourceName); if (entry != null) { @@ -637,18 +656,18 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } } catch (Exception e) { - log("Ignoring Exception " + e.getClass().getName() + ": " + e.getMessage() + - " reading resource " + resourceName + " from " + file, Project.MSG_VERBOSE); + log("Ignoring Exception " + e.getClass().getName() + ": " + e.getMessage() + + " reading resource " + resourceName + " from " + file, Project.MSG_VERBOSE); } - - return null; + + return null; } private boolean isParentFirst(String resourceName) { // default to the global setting and then see // if this class belongs to a package which has been // designated to use a specific loader first (this one or the parent one) - boolean useParentFirst = parentFirst; + boolean useParentFirst = parentFirst; for (Enumeration e = systemPackages.elements(); e.hasMoreElements();) { String packageName = (String)e.nextElement(); @@ -665,19 +684,19 @@ public class AntClassLoader extends ClassLoader implements BuildListener { break; } } - + return useParentFirst; } /** - * Finds the resource with the given name. A resource is + * Finds the resource with the given name. A resource is * some data (images, audio, text, etc) * that can be accessed by class * code in a way that is independent of the location of the code. * * @param name the name of the resource for which a stream is required. * - * @return a URL for reading the resource, or null if the resource + * @return a URL for reading the resource, or null if the resource * could not be found or the caller * doesn't have adequate privileges to get the resource. */ @@ -690,29 +709,29 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } if (url != null) { - log("Resource " + name + " loaded from parent loader", + log("Resource " + name + " loaded from parent loader", Project.MSG_DEBUG); } else { - // try and load from this loader if the parent either didn't find + // try and load from this loader if the parent either didn't find // it or wasn't consulted. for (Enumeration e = pathComponents.elements(); e.hasMoreElements() && url == null; ) { File pathComponent = (File)e.nextElement(); url = getResourceURL(pathComponent, name); if (url != null) { - log("Resource " + name - + " loaded from ant loader", + log("Resource " + name + + " loaded from ant loader", Project.MSG_DEBUG); } } } - + if (url == null && !isParentFirst(name)) { // this loader was first but it didn't find it - try the parent - + url = (parent == null) ? super.getResource(name) : parent.getResource(name); if (url != null) { - log("Resource " + name + " loaded from parent loader", + log("Resource " + name + " loaded from parent loader", Project.MSG_DEBUG); } } @@ -740,12 +759,12 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * Get an inputstream to a given resource in the given file which may * either be a directory or a zip file. * - * @param file the file (directory or jar) in which to search for + * @param file the file (directory or jar) in which to search for * the resource. - * @param resourceName the name of the resource for which a stream + * @param resourceName the name of the resource for which a stream * is required. * - * @return a stream to the required resource or null if the + * @return a stream to the required resource or null if the * resource cannot be found in the given file object */ private URL getResourceURL(File file, String resourceName) { @@ -769,7 +788,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { ZipFile zipFile = (ZipFile)zipFiles.get(file); if (zipFile == null) { zipFile = new ZipFile(file); - zipFiles.put(file, zipFile); + zipFiles.put(file, zipFile); } ZipEntry entry = zipFile.getEntry(resourceName); @@ -793,14 +812,14 @@ public class AntClassLoader extends ClassLoader implements BuildListener { /** * Load a class with this class loader. * - * This method will load a class. + * This method will load a class. * * This class attempts to load the class firstly using the parent class loader. For * JDK 1.1 compatability, this uses the findSystemClass method. * * @param classname the name of the class to be loaded. * @param resolve true if all classes upon which this class depends are to be loaded. - * + * * @return the required Class object * * @throws ClassNotFoundException if the requested class does not exist on @@ -836,7 +855,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { log("Class " + classname + " loaded from parent loader", Project.MSG_DEBUG); } } - + if (resolve) { resolveClass(theClass); } @@ -867,16 +886,16 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * @throws IOException if there is a problem reading the class from the * stream. */ - private Class getClassFromStream(InputStream stream, String classname) + private Class getClassFromStream(InputStream stream, String classname) throws IOException { ByteArrayOutputStream baos = new ByteArrayOutputStream(); int bytesRead = -1; byte[] buffer = new byte[BUFFER_SIZE]; - + while ((bytesRead = stream.read(buffer, 0, BUFFER_SIZE)) != -1) { baos.write(buffer, 0, bytesRead); } - + byte[] classData = baos.toByteArray(); // Simply put: @@ -905,7 +924,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } } else { - return defineClass(classname, classData, 0, classData.length); + return defineClass(classname, classData, 0, classData.length); } } @@ -913,7 +932,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * Search for and load a class on the classpath of this class loader. * * @param name the classname to be loaded. - * + * * @return the required Class object * * @throws ClassNotFoundException if the requested class does not exist on @@ -930,8 +949,8 @@ public class AntClassLoader extends ClassLoader implements BuildListener { * Find a class on the given classpath. */ private Class findClassInComponents(String name) throws ClassNotFoundException { - // we need to search the components of the path to see if we can find the - // class we want. + // we need to search the components of the path to see if we can find the + // class we want. InputStream stream = null; String classFilename = getClassFilename(name); try { @@ -948,7 +967,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { log("Exception reading component " + pathComponent , Project.MSG_VERBOSE); } } - + throw new ClassNotFoundException(name); } finally { @@ -987,7 +1006,7 @@ public class AntClassLoader extends ClassLoader implements BuildListener { } zipFiles = new Hashtable(); } - + public void buildStarted(BuildEvent event) { }