1 files changed, 159 insertions, 0 deletions
diff --git a/netx/net/sourceforge/jnlp/util/lockingfile/LockedFile.java b/netx/net/sourceforge/jnlp/util/lockingfile/LockedFile.java
new file mode 100644
index 0000000..2941dd9
--- /dev/null
+++ b/netx/net/sourceforge/jnlp/util/lockingfile/LockedFile.java
@@ -0,0 +1,159 @@
+/*
+ Copyright (C) 2013 Red Hat, Inc.
+
+ This file is part of IcedTea.
+
+ IcedTea is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, version 2.
+
+ IcedTea is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with IcedTea; see the file COPYING.  If not, write to
+ the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ 02110-1301 USA.
+
+ Linking this library statically or dynamically with other modules is
+ making a combined work based on this library.  Thus, the terms and
+ conditions of the GNU General Public License cover the whole
+ combination.
+
+ As a special exception, the copyright holders of this library give you
+ permission to link this library with independent modules to produce an
+ executable, regardless of the license terms of these independent
+ modules, and to copy and distribute the resulting executable under
+ terms of your choice, provided that you also meet, for each linked
+ independent module, the terms and conditions of the license of that
+ module.  An independent module is a module which is not derived from
+ or based on this library.  If you modify this library, you may extend
+ this exception to your version of the library, but you are not
+ obligated to do so.  If you do not wish to do so, delete this
+ exception statement from your version.
+ */
+package net.sourceforge.jnlp.util.lockingfile;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.channels.FileChannel;
+import java.nio.channels.FileLock;
+import java.util.Map;
+import java.util.WeakHashMap;
+import java.util.concurrent.locks.ReentrantLock;
+
+/*
+ * Process & thread locked access to a file. Creates file if it does not already exist.
+ */
+public class LockedFile {
+
+    // The file for access
+    private RandomAccessFile randomAccessFile;
+    private FileChannel fileChannel;
+    private File file;
+    // A file lock will protect against locks for multiple
+    // processes, while a thread lock is still needed within a single JVM.
+    private FileLock processLock = null;
+    private ReentrantLock threadLock = new ReentrantLock();
+    private boolean readOnly;
+
+    private LockedFile(File file) {
+        this.file = file;
+        try {
+            //just try to create
+            this.file.createNewFile();
+        } catch (Exception ex) {
+            //intentionaly silent
+        }
+        if (!this.file.isFile() && file.getParentFile() != null && !file.getParentFile().canWrite()) {
+            readOnly = true;
+        } else {
+            this.readOnly = !file.canWrite();
+            if (!readOnly && file.getParentFile() != null && !file.getParentFile().canWrite()) {
+                readOnly = true;
+            }
+        }
+    }
+
+    public boolean isReadOnly() {
+        return readOnly;
+    }
+    // Provide shared access to LockedFile's via weak map
+    static private final Map<File, LockedFile> instanceCache = new WeakHashMap<File, LockedFile>();
+
+    /**
+     * Get a LockedFile for a given File. Ensures that we share the same
+     * instance for all threads
+     *
+     * @param file the file to lock
+     * @return a LockedFile instance
+     */
+    synchronized public static LockedFile getInstance(File file) {
+        if (!instanceCache.containsKey(file)) {
+            instanceCache.put(file, new LockedFile(file));
+        }
+
+        return instanceCache.get(file);
+    }
+
+    /**
+     * Get the file being locked.
+     *
+     * @return the file
+     */
+    public File getFile() {
+        return file;
+    }
+
+    /**
+     * Lock access to the file. Lock is reentrant.
+     */
+    public void lock() throws IOException {
+        // Create if does not already exist, cannot lock non-existing file
+        if (!isReadOnly()) {
+            this.file.createNewFile();
+        }
+
+        this.threadLock.lock();
+
+        if (this.processLock != null) {
+            return;
+        }
+
+        if (this.file.exists()) {
+            this.randomAccessFile = new RandomAccessFile(this.file, isReadOnly() ? "r" : "rws");
+            this.fileChannel = randomAccessFile.getChannel();
+            if (!isReadOnly()){
+                this.processLock = this.fileChannel.lock();
+            }
+        }
+    }
+
+    /**
+     * Unlock access to the file. Lock is reentrant.
+     */
+    public void unlock() throws IOException {
+        boolean releaseProcessLock = (this.threadLock.getHoldCount() == 1);
+        try {
+            if (releaseProcessLock) {
+                if (this.processLock != null){
+                    this.processLock.release();
+                }
+                this.processLock = null;
+                //necessary for read only file
+                if (this.randomAccessFile != null){
+                    this.randomAccessFile.close();
+                }
+                //necessary for not existing parent direcotry
+                if (this.fileChannel != null){
+                    this.fileChannel.close();
+                }
+            }
+        } finally {
+            this.threadLock.unlock();
+        }
+    }
+}
+\ No newline at end of file