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 */ 25package sun.tools.attach; 26 27import com.sun.tools.attach.AttachOperationFailedException; 28import com.sun.tools.attach.AgentLoadException; 29import com.sun.tools.attach.AttachNotSupportedException; 30import com.sun.tools.attach.spi.AttachProvider; 31 32import java.io.InputStream; 33import java.io.IOException; 34import java.io.File; 35import java.io.FileNotFoundException; 36 37/* 38 * Solaris implementation of HotSpotVirtualMachine. 39 */ 40public class VirtualMachineImpl extends HotSpotVirtualMachine { 41 // "/tmp" is used as a global well-known location for the files 42 // .java_pid<pid>. and .attach_pid<pid>. It is important that this 43 // location is the same for all processes, otherwise the tools 44 // will not be able to find all Hotspot processes. 45 // Any changes to this needs to be synchronized with HotSpot. 46 private static final String tmpdir = "/tmp"; 47 48 // door descriptor; 49 private int fd = -1; 50 51 /** 52 * Attaches to the target VM 53 */ 54 VirtualMachineImpl(AttachProvider provider, String vmid) 55 throws AttachNotSupportedException, IOException 56 { 57 super(provider, vmid); 58 // This provider only understands process-ids (pids). 59 int pid; 60 try { 61 pid = Integer.parseInt(vmid); 62 } catch (NumberFormatException x) { 63 throw new AttachNotSupportedException("invalid process identifier"); 64 } 65 66 // Opens the door file to the target VM. If the file is not 67 // found it might mean that the attach mechanism isn't started in the 68 // target VM so we attempt to start it and retry. 69 try { 70 fd = openDoor(pid); 71 } catch (FileNotFoundException fnf1) { 72 File f = createAttachFile(pid); 73 try { 74 sigquit(pid); 75 76 // give the target VM time to start the attach mechanism 77 final int delay_step = 100; 78 final long timeout = attachTimeout(); 79 long time_spend = 0; 80 long delay = 0; 81 do { 82 // Increase timeout on each attempt to reduce polling 83 delay += delay_step; 84 try { 85 Thread.sleep(delay); 86 } catch (InterruptedException x) { } 87 try { 88 fd = openDoor(pid); 89 } catch (FileNotFoundException fnf2) { 90 // pass 91 } 92 93 time_spend += delay; 94 if (time_spend > timeout/2 && fd == -1) { 95 // Send QUIT again to give target VM the last chance to react 96 sigquit(pid); 97 } 98 } while (time_spend <= timeout && fd == -1); 99 if (fd == -1) { 100 throw new AttachNotSupportedException( 101 String.format("Unable to open door %s: " + 102 "target process %d doesn't respond within %dms " + 103 "or HotSpot VM not loaded", f.getPath(), pid, time_spend)); 104 } 105 } finally { 106 f.delete(); 107 } 108 } 109 assert fd >= 0; 110 } 111 112 /** 113 * Detach from the target VM 114 */ 115 public void detach() throws IOException { 116 synchronized (this) { 117 if (fd != -1) { 118 close(fd); 119 fd = -1; 120 } 121 } 122 } 123 124 /** 125 * Execute the given command in the target VM. 126 */ 127 InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException { 128 assert args.length <= 3; // includes null 129 130 // first check that we are still attached 131 int door; 132 synchronized (this) { 133 if (fd == -1) { 134 throw new IOException("Detached from target VM"); 135 } 136 door = fd; 137 } 138 139 // enqueue the command via a door call 140 int s = enqueue(door, cmd, args); 141 assert s >= 0; // valid file descriptor 142 143 // The door call returns a file descriptor (one end of a socket pair). 144 // Create an input stream around it. 145 SocketInputStream sis = new SocketInputStream(s); 146 147 // Read the command completion status 148 int completionStatus; 149 try { 150 completionStatus = readInt(sis); 151 } catch (IOException ioe) { 152 sis.close(); 153 throw ioe; 154 } 155 156 // If non-0 it means an error but we need to special-case the 157 // "load" command to ensure that the right exception is thrown. 158 if (completionStatus != 0) { 159 // read from the stream and use that as the error message 160 String message = readErrorMessage(sis); 161 sis.close(); 162 if (cmd.equals("load")) { 163 String msg = "Failed to load agent library"; 164 if (!message.isEmpty()) 165 msg += ": " + message; 166 throw new AgentLoadException(msg); 167 } else { 168 if (message.isEmpty()) 169 message = "Command failed in target VM"; 170 throw new AttachOperationFailedException(message); 171 } 172 } 173 174 // Return the input stream so that the command output can be read 175 return sis; 176 } 177 178 // InputStream over a socket 179 private class SocketInputStream extends InputStream { 180 int s; 181 182 public SocketInputStream(int s) { 183 this.s = s; 184 } 185 186 public synchronized int read() throws IOException { 187 byte b[] = new byte[1]; 188 int n = this.read(b, 0, 1); 189 if (n == 1) { 190 return b[0] & 0xff; 191 } else { 192 return -1; 193 } 194 } 195 196 public synchronized int read(byte[] bs, int off, int len) throws IOException { 197 if ((off < 0) || (off > bs.length) || (len < 0) || 198 ((off + len) > bs.length) || ((off + len) < 0)) { 199 throw new IndexOutOfBoundsException(); 200 } else if (len == 0) 201 return 0; 202 203 return VirtualMachineImpl.read(s, bs, off, len); 204 } 205 206 public void close() throws IOException { 207 VirtualMachineImpl.close(s); 208 } 209 } 210 211 // The door is attached to .java_pid<pid> in the temporary directory. 212 private int openDoor(int pid) throws IOException { 213 String path = tmpdir + "/.java_pid" + pid;; 214 fd = open(path); 215 216 // Check that the file owner/permission to avoid attaching to 217 // bogus process 218 try { 219 checkPermissions(path); 220 } catch (IOException ioe) { 221 close(fd); 222 throw ioe; 223 } 224 return fd; 225 } 226 227 // On Solaris/Linux a simple handshake is used to start the attach mechanism 228 // if not already started. The client creates a .attach_pid<pid> file in the 229 // target VM's working directory (or temporary directory), and the SIGQUIT 230 // handler checks for the file. 231 private File createAttachFile(int pid) throws IOException { 232 String fn = ".attach_pid" + pid; 233 String path = "/proc/" + pid + "/cwd/" + fn; 234 File f = new File(path); 235 try { 236 f.createNewFile(); 237 } catch (IOException x) { 238 f = new File(tmpdir, fn); 239 f.createNewFile(); 240 } 241 return f; 242 } 243 244 //-- native methods 245 246 static native int open(String path) throws IOException; 247 248 static native void close(int fd) throws IOException; 249 250 static native int read(int fd, byte buf[], int off, int buflen) throws IOException; 251 252 static native void checkPermissions(String path) throws IOException; 253 254 static native void sigquit(int pid) throws IOException; 255 256 // enqueue a command (and arguments) to the given door 257 static native int enqueue(int fd, String cmd, Object ... args) 258 throws IOException; 259 260 static { 261 System.loadLibrary("attach"); 262 } 263} 264