Don't open the file used for <exec output="file"> and friends before

it gets actually written.

Needed to fix PR: 13652


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@275143 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/Redirector.java

@@ -57,9 +57,8 @@ import java.io.BufferedReader;
 import java.io.ByteArrayOutputStream;
 import java.io.ByteArrayInputStream;
 import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.FileOutputStream;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.StringReader;
 import java.io.OutputStream;
@@ -68,6 +67,7 @@ import java.io.PrintStream;
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Project;
 import org.apache.tools.ant.Task;
+import org.apache.tools.ant.util.DelayedFileOutputStream;
 import org.apache.tools.ant.util.StringUtils;
 import org.apache.tools.ant.util.TeeOutputStream;
 
@@ -269,16 +269,10 @@ public class Redirector {
             errorStream = new LogOutputStream(managingTask, Project.MSG_WARN);
         } else {
             if (out != null)  {
-                try {
                     outputStream
-                        = new FileOutputStream(out.getAbsolutePath(), append);
+                        = new DelayedFileOutputStream(out, append);
                     managingTask.log("Output redirected to " + out,
                                      Project.MSG_VERBOSE);
-                } catch (FileNotFoundException fne) {
-                    throw new BuildException("Cannot write to " + out, fne);
-                } catch (IOException ioe) {
-                    throw new BuildException("Cannot write to " + out, ioe);
-                }
             }
 
             if (outputProperty != null) {
@@ -302,16 +296,10 @@ public class Redirector {
         }
 
         if (error != null)  {
-            try {
                 errorStream
-                    = new FileOutputStream(error.getAbsolutePath(), append);
+                    = new DelayedFileOutputStream(error, append);
                 managingTask.log("Error redirected to " + error,
                     Project.MSG_VERBOSE);
-            } catch (FileNotFoundException fne) {
-                throw new BuildException("Cannot write to " + error, fne);
-            } catch (IOException ioe) {
-                throw new BuildException("Cannot write to " + error, ioe);
-            }
         }
 
         if (errorProperty != null) {

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

@@ -0,0 +1,155 @@
+/*
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2003 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution, if
+ *    any, must include the following acknowlegement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowlegement may appear in the software itself,
+ *    if and wherever such third-party acknowlegements normally appear.
+ *
+ * 4. The names "Ant" and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+package org.apache.tools.ant.util;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * Class that delays opening the output file until the first bytes
+ * shall be written or the method {@link #open open} has been invoked
+ * explicitly.
+ *
+ * @since Ant 1.6
+ */
+public class DelayedFileOutputStream extends OutputStream {
+
+    private FileOutputStream fos;
+    private File file;
+    private boolean append;
+    private boolean opened = false;
+    private boolean closed = false;
+
+    /**
+     * Creates a stream that will eventually write to the file with
+     * the given name and replace it.
+     */
+    public DelayedFileOutputStream(String name) {
+        this(name, false);
+    }
+
+    /**
+     * Creates a stream that will eventually write to the file with
+     * the given name and optionally append to instead of replacing
+     * it.
+     */
+    public DelayedFileOutputStream(String name, boolean append) {
+        this(new File(name), append);
+    }
+
+    /**
+     * Creates a stream that will eventually write to the file with
+     * the given name and replace it.
+     */
+    public DelayedFileOutputStream(File f) {
+        this(f, false);
+    }
+
+    /**
+     * Creates a stream that will eventually write to the file with
+     * the given name and optionally append to instead of replacing
+     * it.
+     */
+    public DelayedFileOutputStream(File file, boolean append) {
+        this.file = file;
+        this.append = append;
+    }
+
+    /**
+     * Explicitly open the file for writing.
+     *
+     * <p>Returns silently if the file has already been opened.</p>
+     */
+    public void open() throws IOException {
+        ensureOpened();
+    }
+
+    public synchronized void close() throws IOException {
+        if (opened) {
+            fos.close();
+        }
+        closed = true;
+    }
+
+    /**
+     * Delegates to the three arg version.
+     */
+    public void write(byte[] b) throws IOException {
+        write(b, 0, b.length);
+    }
+
+    public synchronized void write(byte[] b, int offset, int len) 
+        throws IOException {
+        ensureOpened();
+        fos.write(b, offset, len);
+    }
+
+    public synchronized void write(int b) throws IOException {
+        ensureOpened();
+        fos.write(b);
+    }
+
+    private synchronized void ensureOpened() throws IOException {
+        if (closed) {
+            throw new IOException(file + " has already been closed.");
+        }
+
+        if (!opened) {
+            fos = new FileOutputStream(file.getAbsolutePath(), append);
+            opened = true;
+        }
+    }
+}