1 /*

     2  * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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

    15  * accompanied this code).

    16  *

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

    18  * 2 along with this work; if not, write to the Free Software Foundation,

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

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package sun.tools.attach;

    26 

    27 import com.sun.tools.attach.AttachOperationFailedException;

    28 import com.sun.tools.attach.AgentLoadException;

    29 import com.sun.tools.attach.AttachNotSupportedException;

    30 import com.sun.tools.attach.spi.AttachProvider;

    31 

    32 import java.io.InputStream;

    33 import java.io.IOException;

    34 import java.io.File;

    35 

    36 /*

    37  * Bsd implementation of HotSpotVirtualMachine

    38  */

    39 public class BsdVirtualMachine extends HotSpotVirtualMachine {

    40     // "tmpdir" is used as a global well-known location for the files

    41     // .java_pid<pid>. and .attach_pid<pid>. It is important that this

    42     // location is the same for all processes, otherwise the tools

    43     // will not be able to find all Hotspot processes.

    44     // This is intentionally not the same as java.io.tmpdir, since

    45     // the latter can be changed by the user.

    46     // Any changes to this needs to be synchronized with HotSpot.

    47     private static final String tmpdir;

    48 

    49     // The patch to the socket file created by the target VM

    50     String path;

    51 

    52     /**

    53      * Attaches to the target VM

    54      */

    55     BsdVirtualMachine(AttachProvider provider, String vmid)

    56         throws AttachNotSupportedException, IOException

    57     {

    58         super(provider, vmid);

    59 

    60         // This provider only understands pids

    61         int pid;

    62         try {

    63             pid = Integer.parseInt(vmid);

    64         } catch (NumberFormatException x) {

    65             throw new AttachNotSupportedException("Invalid process identifier");

    66         }

    67 

    68         // Find the socket file. If not found then we attempt to start the

    69         // attach mechanism in the target VM by sending it a QUIT signal.

    70         // Then we attempt to find the socket file again.

    71         path = findSocketFile(pid);

    72         if (path == null) {

    73             File f = new File(tmpdir, ".attach_pid" + pid);

    74             createAttachFile(f.getPath());

    75             try {

    76                 sendQuitTo(pid);

    77 

    78                 // give the target VM time to start the attach mechanism

    79                 int i = 0;

    80                 long delay = 200;

    81                 int retries = (int)(attachTimeout() / delay);

    82                 do {

    83                     try {

    84                         Thread.sleep(delay);

    85                     } catch (InterruptedException x) { }

    86                     path = findSocketFile(pid);

    87                     i++;

    88                 } while (i <= retries && path == null);

    89                 if (path == null) {

    90                     throw new AttachNotSupportedException(

    91                         "Unable to open socket file: target process not responding " +

    92                         "or HotSpot VM not loaded");

    93                 }

    94             } finally {

    95                 f.delete();

    96             }

    97         }

    98 

    99         // Check that the file owner/permission to avoid attaching to

   100         // bogus process

   101         checkPermissions(path);

   102 

   103         // Check that we can connect to the process

   104         // - this ensures we throw the permission denied error now rather than

   105         // later when we attempt to enqueue a command.

   106         int s = socket();

   107         try {

   108             connect(s, path);

   109         } finally {

   110             close(s);

   111         }

   112     }

   113 

   114     /**

   115      * Detach from the target VM

   116      */

   117     public void detach() throws IOException {

   118         synchronized (this) {

   119             if (this.path != null) {

   120                 this.path = null;

   121             }

   122         }

   123     }

   124 

   125     // protocol version

   126     private final static String PROTOCOL_VERSION = "1";

   127 

   128     // known errors

   129     private final static int ATTACH_ERROR_BADVERSION = 101;

   130 

   131     /**

   132      * Execute the given command in the target VM.

   133      */

   134     InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException {

   135         assert args.length <= 3;                // includes null

   136 

   137         // did we detach?

   138         String p;

   139         synchronized (this) {

   140             if (this.path == null) {

   141                 throw new IOException("Detached from target VM");

   142             }

   143             p = this.path;

   144         }

   145 

   146         // create UNIX socket

   147         int s = socket();

   148 

   149         // connect to target VM

   150         try {

   151             connect(s, p);

   152         } catch (IOException x) {

   153             close(s);

   154             throw x;

   155         }

   156 

   157         IOException ioe = null;

   158 

   159         // connected - write request

   160         // <ver> <cmd> <args...>

   161         try {

   162             writeString(s, PROTOCOL_VERSION);

   163             writeString(s, cmd);

   164 

   165             for (int i=0; i<3; i++) {

   166                 if (i < args.length && args[i] != null) {

   167                     writeString(s, (String)args[i]);

   168                 } else {

   169                     writeString(s, "");

   170                 }

   171             }

   172         } catch (IOException x) {

   173             ioe = x;

   174         }

   175 

   176 

   177         // Create an input stream to read reply

   178         SocketInputStream sis = new SocketInputStream(s);

   179 

   180         // Read the command completion status

   181         int completionStatus;

   182         try {

   183             completionStatus = readInt(sis);

   184         } catch (IOException x) {

   185             sis.close();

   186             if (ioe != null) {

   187                 throw ioe;

   188             } else {

   189                 throw x;

   190             }

   191         }

   192 

   193         if (completionStatus != 0) {

   194             // read from the stream and use that as the error message

   195             String message = readErrorMessage(sis);

   196             sis.close();

   197 

   198             // In the event of a protocol mismatch then the target VM

   199             // returns a known error so that we can throw a reasonable

   200             // error.

   201             if (completionStatus == ATTACH_ERROR_BADVERSION) {

   202                 throw new IOException("Protocol mismatch with target VM");

   203             }

   204 

   205             // Special-case the "load" command so that the right exception is

   206             // thrown.

   207             if (cmd.equals("load")) {

   208                 throw new AgentLoadException("Failed to load agent library");

   209             } else {

   210                 if (message == null) {

   211                     throw new AttachOperationFailedException("Command failed in target VM");

   212                 } else {

   213                     throw new AttachOperationFailedException(message);

   214                 }

   215             }

   216         }

   217 

   218         // Return the input stream so that the command output can be read

   219         return sis;

   220     }

   221 

   222     /*

   223      * InputStream for the socket connection to get target VM

   224      */

   225     private class SocketInputStream extends InputStream {

   226         int s;

   227 

   228         public SocketInputStream(int s) {

   229             this.s = s;

   230         }

   231 

   232         public synchronized int read() throws IOException {

   233             byte b[] = new byte[1];

   234             int n = this.read(b, 0, 1);

   235             if (n == 1) {

   236                 return b[0] & 0xff;

   237             } else {

   238                 return -1;

   239             }

   240         }

   241 

   242         public synchronized int read(byte[] bs, int off, int len) throws IOException {

   243             if ((off < 0) || (off > bs.length) || (len < 0) ||

   244                 ((off + len) > bs.length) || ((off + len) < 0)) {

   245                 throw new IndexOutOfBoundsException();

   246             } else if (len == 0) {

   247                 return 0;

   248             }

   249 

   250             return BsdVirtualMachine.read(s, bs, off, len);

   251         }

   252 

   253         public void close() throws IOException {

   254             BsdVirtualMachine.close(s);

   255         }

   256     }

   257 

   258     // Return the socket file for the given process.

   259     // Checks temp directory for .java_pid<pid>.

   260     private String findSocketFile(int pid) {

   261         String fn = ".java_pid" + pid;

   262         File f = new File(tmpdir, fn);

   263         return f.exists() ? f.getPath() : null;

   264     }

   265 

   266     /*

   267      * Write/sends the given to the target VM. String is transmitted in

   268      * UTF-8 encoding.

   269      */

   270     private void writeString(int fd, String s) throws IOException {

   271         if (s.length() > 0) {

   272             byte b[];

   273             try {

   274                 b = s.getBytes("UTF-8");

   275             } catch (java.io.UnsupportedEncodingException x) {

   276                 throw new InternalError();

   277             }

   278             BsdVirtualMachine.write(fd, b, 0, b.length);

   279         }

   280         byte b[] = new byte[1];

   281         b[0] = 0;

   282         write(fd, b, 0, 1);

   283     }

   284 

   285 

   286     //-- native methods

   287 

   288     static native void sendQuitTo(int pid) throws IOException;

   289 

   290     static native void checkPermissions(String path) throws IOException;

   291 

   292     static native int socket() throws IOException;

   293 

   294     static native void connect(int fd, String path) throws IOException;

   295 

   296     static native void close(int fd) throws IOException;

   297 

   298     static native int read(int fd, byte buf[], int off, int bufLen) throws IOException;

   299 

   300     static native void write(int fd, byte buf[], int off, int bufLen) throws IOException;

   301 

   302     static native void createAttachFile(String path);

   303 

   304     static native String getTempDir();

   305 

   306     static {

   307         System.loadLibrary("attach");

   308         tmpdir = getTempDir();

   309     }

   310 }