Impossible to use implicit classpath for <taskdef> when Ant core loader != Java application loader and Path.systemClassPath taken from ${java.class.path}

PR: 30161
Submitted by: Jesse Glick (jglick at netbeans dot org)


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276721 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -48,6 +48,10 @@ Fixed bugs:
 * AbstractCvsTask prematurely closed its outputStream and errorStream.
   Bugzilla 30097.
 
+* Impossible to use implicit classpath for <taskdef>
+  when Ant core loader != Java application loader and Path.systemClassPath taken from ${java.class.path}
+  Bugzilla 30161.  
+
 Changes from Ant 1.6.1 to Ant 1.6.2
 ===================================
 

build.xml

@@ -1456,7 +1456,7 @@
       <classpath refid="tests-classpath"/>
 
       <sysproperty key="ant.home" value="${ant.home}"/>
-      <sysproperty key="build.tests" value="${build.tests}"/>
+      <sysproperty key="build.tests" file="${build.tests}"/>
       <sysproperty key="build.tests.value" value="${build.tests.value}"/>
       <sysproperty key="tests-classpath.value"
                    value="${tests-classpath.value}"/>
@@ -1606,7 +1606,7 @@
           filtertrace="${junit.filtertrace}">
 <!--      <jvmarg value="-classic"/> -->
       <sysproperty key="ant.home" value="${ant.home}"/>
-      <sysproperty key="build.tests" value="${build.tests}"/>
+      <sysproperty key="build.tests" file="${build.tests}"/>
       <sysproperty key="build.tests.value" value="${build.tests.value}"/>
       <sysproperty key="tests-classpath.value"
                    value="${tests-classpath.value}"/>

src/main/org/apache/tools/ant/AntClassLoader.java

@@ -32,6 +32,7 @@ import java.util.Vector;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 import org.apache.tools.ant.types.Path;
+import org.apache.tools.ant.util.CollectionUtils;
 import org.apache.tools.ant.util.FileUtils;
 import org.apache.tools.ant.util.JavaEnvUtils;
 import org.apache.tools.ant.util.LoaderUtils;
@@ -864,8 +865,24 @@ public class AntClassLoader extends ClassLoader implements SubBuildListener {
      * @return an enumeration of URLs for the resources
      * @exception IOException if I/O errors occurs (can't happen)
      */
-    protected Enumeration findResources(String name) throws IOException {
-        return new ResourceEnumeration(name);
+    protected Enumeration/*<URL>*/ findResources(String name) throws IOException {
+        Enumeration/*<URL>*/ mine = new ResourceEnumeration(name);
+        Enumeration/*<URL>*/ base;
+        if (parent != null && parent != getParent()) {
+            // Delegate to the parent:
+            base = parent.getResources(name);
+            // Note: could cause overlaps in case ClassLoader.this.parent has matches.
+        } else {
+            // ClassLoader.this.parent is already delegated to from ClassLoader.getResources, no need:
+            base = new CollectionUtils.EmptyEnumeration();
+        }
+        if (isParentFirst(name)) {
+            // Normal case.
+            return CollectionUtils.append(base, mine);
+        } else {
+            // Inverted.
+            return CollectionUtils.append(mine, base);
+        }
     }
 
     /**

src/main/org/apache/tools/ant/util/CollectionUtils.java

@@ -113,4 +113,39 @@ public class CollectionUtils {
         }
     }
 
+    /**
+     * Append one enumeration to another.
+     * Elements are evaluated lazily.
+     * @param e1 the first enumeration
+     * @param e2 the subsequent enumeration
+     * @return an enumeration representing e1 followed by e2
+     * @since Ant 1.6.3
+     */
+    public static Enumeration append(Enumeration e1, Enumeration e2) {
+        return new CompoundEnumeration(e1, e2);
+    }
+
+    private static final class CompoundEnumeration implements Enumeration {
+
+        private final Enumeration e1, e2;
+
+        public CompoundEnumeration(Enumeration e1, Enumeration e2) {
+            this.e1 = e1;
+            this.e2 = e2;
+        }
+
+        public boolean hasMoreElements() {
+            return e1.hasMoreElements() || e2.hasMoreElements();
+        }
+
+        public Object nextElement() throws NoSuchElementException {
+            if (e1.hasMoreElements()) {
+                return e1.nextElement();
+            } else {
+                return e2.nextElement();
+            }
+        }
+
+    }
+
 }

src/testcases/org/apache/tools/ant/AntClassLoaderTest.java

@@ -16,8 +16,20 @@
  */
 
 package org.apache.tools.ant;
-import org.apache.tools.ant.types.Path;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
 import junit.framework.TestCase;
+import org.apache.tools.ant.BuildException;
+import org.apache.tools.ant.Project;
+import org.apache.tools.ant.types.Path;
+import org.apache.tools.ant.util.FileUtils;
 
 /**
  * Test case for ant class loader
@@ -70,5 +82,56 @@ public class AntClassLoaderTest extends TestCase {
             fail("loader should not fail even if project finished");
         }
     }
+    
+    /** Sample resource present in build/testcases/ */
+    private static final String TEST_RESOURCE = "org/apache/tools/ant/IncludeTest.class";
+    
+    public void testFindResources() throws Exception {
+        //System.err.println("loading from: " + AntClassLoader.class.getProtectionDomain().getCodeSource().getLocation());
+        // See bug #30161.
+        // This path should contain the class files for these testcases:
+        String buildTestcases = System.getProperty("build.tests");
+        assertNotNull("defined ${build.tests}", buildTestcases);
+        assertTrue("have a dir " + buildTestcases, new File(buildTestcases).isDirectory());
+        Path path = new Path(p, buildTestcases);
+        // A special parent loader which is not the system class loader:
+        ClassLoader parent = new ParentLoader();
+        // An AntClassLoader which is supposed to delegate to the parent and then to the disk path:
+        ClassLoader acl = new AntClassLoader(parent, p, path, true);
+        // The intended result URLs:
+        URL urlFromPath = new URL(FileUtils.newFileUtils().toURI(buildTestcases) + TEST_RESOURCE);
+        URL urlFromParent = new URL("http://ant.apache.org/" + TEST_RESOURCE);
+        assertEquals("correct resources (regular delegation order)",
+            Arrays.asList(new URL[] {urlFromParent, urlFromPath}),
+            enum2List(acl.getResources(TEST_RESOURCE)));
+        acl = new AntClassLoader(parent, p, path, false);
+        assertEquals("correct resources (reverse delegation order)",
+            Arrays.asList(new URL[] {urlFromPath, urlFromParent}),
+            enum2List(acl.getResources(TEST_RESOURCE)));
+    }
+    
+    private static List enum2List(Enumeration e) {
+        // JDK 1.4: return Collections.list(e);
+        List l = new ArrayList();
+        while (e.hasMoreElements()) {
+            l.add(e.nextElement());
+        }
+        return l;
+    }
+    
+    /** Special loader that just knows how to find TEST_RESOURCE. */
+    private static final class ParentLoader extends ClassLoader {
+        
+        public ParentLoader() {}
+        
+        protected Enumeration findResources(String name) throws IOException {
+            if (name.equals(TEST_RESOURCE)) {
+                return Collections.enumeration(Collections.singleton(new URL("http://ant.apache.org/" + name)));
+            } else {
+                return Collections.enumeration(Collections.EMPTY_SET);
+            }
+        }
+        
+    }
+    
 }
-