/*

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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 */

/*

 * @test

 * @bug 7162400

 * @key regression

 * @summary Regression test for attach issue where stale pid files in /tmp lead to connection issues

 * @library /testlibrary

 * @compile AttachWithStalePidFileTarget.java

 * @run main AttachWithStalePidFile

 */

import com.oracle.java.testlibrary.*;

import com.sun.tools.attach.VirtualMachine;

import sun.tools.attach.HotSpotVirtualMachine;

import java.lang.reflect.Field;

import java.nio.file.*;

import java.nio.file.attribute.*;

import java.io.*;

public class AttachWithStalePidFile {

  public static void main(String... args) throws Exception {

    // this test is only valid on non-Windows platforms

    if(Platform.isWindows()) {

      System.out.println("This test is only valid on non-Windows platforms.");

      return;

    }

    // Since there might be stale pid-files owned by different

    // users on the system we may need to retry the test in case we

    // are unable to remove the existing file.

    int retries = 5;

    while(!runTest() && --retries > 0);

    if(retries == 0) {

      throw new RuntimeException("Test failed after 5 retries. " +

        "Remove any /tmp/.java_pid* files and retry.");

    }

  }

  public static boolean runTest() throws Exception {

    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

      "-XX:+UnlockDiagnosticVMOptions", "-XX:+PauseAtStartup", "AttachWithStalePidFileTarget");

    Process target = pb.start();

    Path pidFile = null;

    try {

      int pid = getUnixProcessId(target);

      // create the stale .java_pid file. use hard-coded /tmp path as in th VM

      pidFile = createJavaPidFile(pid);

      if(pidFile == null) {

        return false;

      }

      // wait for vm.paused file to be created and delete it once we find it.

      waitForAndResumeVM(pid);

      // unfortunately there's no reliable way to know the VM is ready to receive the

      // attach request so we have to do an arbitrary sleep.

      Thread.sleep(5000);

      HotSpotVirtualMachine vm = (HotSpotVirtualMachine)VirtualMachine.attach(((Integer)pid).toString());

      BufferedReader remoteDataReader = new BufferedReader(new InputStreamReader(vm.remoteDataDump()));

      String line = null;

      while((line = remoteDataReader.readLine()) != null);

      vm.detach();

      return true;

    }

    finally {

      target.destroy();

      target.waitFor();

      if(pidFile != null && Files.exists(pidFile)) {

        Files.delete(pidFile);

      }

    }

  }

  private static Path createJavaPidFile(int pid) throws Exception {

    Path pidFile = Paths.get("/tmp/.java_pid" + pid);

    if(Files.exists(pidFile)) {

      try {

        Files.delete(pidFile);

      }

      catch(FileSystemException e) {

        if(e.getReason().equals("Operation not permitted")) {

          System.out.println("Unable to remove exisiting stale PID file" + pidFile);

          return null;

        }

        throw e;

      }

    }

    return Files.createFile(pidFile,

      PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("rw-------")));

  }

  private static void waitForAndResumeVM(int pid) throws Exception {

    Path pauseFile = Paths.get("vm.paused." + pid);

    int retries = 60;

    while(!Files.exists(pauseFile) && --retries > 0) {

      Thread.sleep(1000);

    }

    if(retries == 0) {

      throw new RuntimeException("Timeout waiting for VM to start. " +

        "vm.paused file not created within 60 seconds.");

    }

    Files.delete(pauseFile);

  }

  private static int getUnixProcessId(Process unixProcess) throws Exception {

    Field pidField = unixProcess.getClass().getDeclaredField("pid");

    pidField.setAccessible(true);

    return (Integer)pidField.get(unixProcess);

  }

}