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// Copyright (C) 2009 Red Hat, Inc.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
package net.sourceforge.jnlp.services;
import static net.sourceforge.jnlp.runtime.Translator.R;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.net.BindException;
import java.net.ServerSocket;
import net.sourceforge.jnlp.JNLPFile;
import net.sourceforge.jnlp.runtime.JNLPRuntime;
import net.sourceforge.jnlp.util.FileUtils;
/**
* This class represents a Lock for single instance jnlp applications
*
* The lock is per-session, per user.
*
* @author <a href="mailto:omajid@redhat.com">Omair Majid</a>
*/
class SingleInstanceLock {
JNLPFile jnlpFile;
File lockFile = null;
public static final int INVALID_PORT = Integer.MIN_VALUE;
int port = INVALID_PORT;
/**
* Create an object to manage the instance lock for the specified JNLP file.
*
* @param jnlpFile the jnlpfile to create the lock for
*/
public SingleInstanceLock(JNLPFile jnlpFile) {
this.jnlpFile = jnlpFile;
lockFile = getLockFile();
}
/**
* Create/overwrite the instance lock for the jnlp file.
*
* @param localPort the network port for the lock
* @throws IOException on any io problems
*/
public void createWithPort(int localPort) throws IOException {
BufferedWriter lockFileWriter = new BufferedWriter(new FileWriter(lockFile, false));
lockFileWriter.write(String.valueOf(localPort));
lockFileWriter.newLine();
lockFileWriter.flush();
lockFileWriter.close();
}
/**
* Returns true if the lock if valid. That is, the lock exists, and port it
* points to is listening for incoming messages.
*/
public boolean isValid() {
return (exists() && getPort() != INVALID_PORT && !isPortFree(getPort()));
}
/**
* Returns the port in this lock file.
*/
public int getPort() {
if (!exists()) {
return INVALID_PORT;
}
try {
parseFile();
} catch (NumberFormatException e) {
port = INVALID_PORT;
} catch (IOException e) {
port = INVALID_PORT;
}
return port;
}
/**
* Returns true if the lock file already exists.
*/
private boolean exists() {
return lockFile.exists();
}
/**
* Returns true if the port is free.
*/
private boolean isPortFree(int port) {
try {
ServerSocket socket = new ServerSocket(port);
socket.close();
return true;
} catch (BindException e) {
return false;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
/**
* Return a file object that represents the lock file. The lock file itself
* may or may not exist.
*/
private File getLockFile() {
File baseDir = new File(JNLPRuntime.LOCKS_DIR);
if (!baseDir.isDirectory() && !baseDir.mkdirs()) {
throw new RuntimeException(R("RNoLockDir", baseDir));
}
String lockFileName = getLockFileName();
File applicationLockFile = new File(baseDir, lockFileName);
return applicationLockFile;
}
/**
* Returns the name of the lock file.
*/
private String getLockFileName() {
String initialName = "";
if (jnlpFile.getSourceLocation() != null) {
initialName = initialName + jnlpFile.getSourceLocation();
} else {
initialName = initialName + jnlpFile.getFileLocation();
}
if (jnlpFile.getFileVersion() != null) {
initialName = initialName + jnlpFile.getFileVersion().toString();
}
initialName = initialName + getCurrentDisplay();
return FileUtils.sanitizeFileName(initialName);
}
/**
* Parse the lock file.
*
* @throws NumberFormatException
* @throws IOException
*/
private void parseFile() throws NumberFormatException, IOException {
BufferedReader lockFileReader = new BufferedReader(new FileReader(lockFile));
int port = Integer.valueOf(lockFileReader.readLine());
lockFileReader.close();
this.port = port;
}
/**
* Returns a string identifying this display.
*
* Implementation note: On systems with X support, this is the DISPLAY
* variable
*
* @return a string that is guaranteed to be not null.
*/
private String getCurrentDisplay() {
String display = System.getenv("DISPLAY");
return (display == null) ? "" : display;
}
}
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