*** old/src/jdk.attach/linux/classes/sun/tools/attach/VirtualMachineImpl.java	Thu Jan 11 13:32:19 2018
--- new/src/jdk.attach/linux/classes/sun/tools/attach/VirtualMachineImpl.java	Thu Jan 11 13:32:18 2018

*** 1,7 ****
--- 1,7 ----
  /*
!  * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this

*** 34,43 ****
--- 34,44 ----
  import java.io.File;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.nio.file.Files;
+ import jdk.internal.vm.VMSupport;
  
  /*
   * Linux implementation of HotSpotVirtualMachine
   */
  public class VirtualMachineImpl extends HotSpotVirtualMachine {

*** 66,76 ****
--- 67,77 ----
          } catch (NumberFormatException x) {
              throw new AttachNotSupportedException("Invalid process identifier");
          }
  
          // Try to resolve to the "inner most" pid namespace
!         int ns_pid = getNamespacePid(pid);
!         int ns_pid = VMSupport.getNamespaceVmId(pid);
  
          // Find the socket file. If not found then we attempt to start the
          // attach mechanism in the target VM by sending it a QUIT signal.
          // Then we attempt to find the socket file again.
          path = findSocketFile(pid, ns_pid);

*** 324,368 ****
--- 325,334 ----
          byte b[] = new byte[1];
          b[0] = 0;
          write(fd, b, 0, 1);
      }
  
  
      // Return the inner most namespaced PID if there is one,
      // otherwise return the original PID.
      private int getNamespacePid(int pid) throws AttachNotSupportedException, IOException {
          // Assuming a real procfs sits beneath, reading this doesn't block
          // nor will it consume a lot of memory.
          String statusFile = "/proc/" + pid + "/status";
          File f = new File(statusFile);
          if (!f.exists()) {
              return pid; // Likely a bad pid, but this is properly handled later.
          }
  
          Path statusPath = Paths.get(statusFile);
  
          try {
              for (String line : Files.readAllLines(statusPath, StandardCharsets.UTF_8)) {
                  String[] parts = line.split(":");
                  if (parts.length == 2 && parts[0].trim().equals("NSpid")) {
                      parts = parts[1].trim().split("\\s+");
                      // The last entry represents the PID the JVM "thinks" it is.
                      // Even in non-namespaced pids these entries should be
                      // valid. You could refer to it as the inner most pid.
                      int ns_pid = Integer.parseInt(parts[parts.length - 1]);
                      return ns_pid;
                  }
              }
              // Old kernels may not have NSpid field (i.e. 3.10).
              // Fallback to original pid in the event we cannot deduce.
              return pid;
          } catch (NumberFormatException | IOException x) {
              throw new AttachNotSupportedException("Unable to parse namespace");
          }
      }
  
  
      //-- native methods
  
      static native void sendQuitToChildrenOf(int pid) throws IOException;
  
      static native void sendQuitTo(int pid) throws IOException;