1/* 2 * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2015 SAP SE. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. Oracle designates this 9 * particular file as subject to the "Classpath" exception as provided 10 * by Oracle in the LICENSE file that accompanied this code. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 * or visit www.oracle.com if you need additional information or have any 24 * questions. 25 */ 26package sun.tools.attach; 27 28import com.sun.tools.attach.AttachOperationFailedException; 29import com.sun.tools.attach.AgentLoadException; 30import com.sun.tools.attach.AttachNotSupportedException; 31import com.sun.tools.attach.spi.AttachProvider; 32 33import java.io.InputStream; 34import java.io.IOException; 35import java.io.File; 36 37// Based on linux/classes/sun/tools/attach/VirtualMachineImpl.java. 38 39/* 40 * Aix implementation of HotSpotVirtualMachine 41 */ 42public class VirtualMachineImpl extends HotSpotVirtualMachine { 43 // "/tmp" is used as a global well-known location for the files 44 // .java_pid<pid>. and .attach_pid<pid>. It is important that this 45 // location is the same for all processes, otherwise the tools 46 // will not be able to find all Hotspot processes. 47 // Any changes to this needs to be synchronized with HotSpot. 48 private static final String tmpdir = "/tmp"; 49 50 // The patch to the socket file created by the target VM 51 String path; 52 53 /** 54 * Attaches to the target VM 55 */ 56 VirtualMachineImpl(AttachProvider provider, String vmid) 57 throws AttachNotSupportedException, IOException 58 { 59 super(provider, vmid); 60 61 // This provider only understands pids 62 int pid; 63 try { 64 pid = Integer.parseInt(vmid); 65 } catch (NumberFormatException x) { 66 throw new AttachNotSupportedException("Invalid process identifier"); 67 } 68 69 // Find the socket file. If not found then we attempt to start the 70 // attach mechanism in the target VM by sending it a QUIT signal. 71 // Then we attempt to find the socket file again. 72 path = findSocketFile(pid); 73 if (path == null) { 74 File f = createAttachFile(pid); 75 try { 76 sendQuitTo(pid); 77 78 // give the target VM time to start the attach mechanism 79 final int delay_step = 100; 80 final long timeout = attachTimeout(); 81 long time_spend = 0; 82 long delay = 0; 83 do { 84 // Increase timeout on each attempt to reduce polling 85 delay += delay_step; 86 try { 87 Thread.sleep(delay); 88 } catch (InterruptedException x) { } 89 path = findSocketFile(pid); 90 91 time_spend += delay; 92 if (time_spend > timeout/2 && path == null) { 93 // Send QUIT again to give target VM the last chance to react 94 sendQuitTo(pid); 95 } 96 } while (time_spend <= timeout && path == null); 97 if (path == null) { 98 throw new AttachNotSupportedException( 99 String.format("Unable to open socket file %s: " + 100 "target process %d doesn't respond within %dms " + 101 "or HotSpot VM not loaded", f.getPath(), pid, time_spend)); 102 } 103 } finally { 104 f.delete(); 105 } 106 } 107 108 // Check that the file owner/permission to avoid attaching to 109 // bogus process 110 checkPermissions(path); 111 112 // Check that we can connect to the process 113 // - this ensures we throw the permission denied error now rather than 114 // later when we attempt to enqueue a command. 115 int s = socket(); 116 try { 117 connect(s, path); 118 } finally { 119 close(s); 120 } 121 } 122 123 /** 124 * Detach from the target VM 125 */ 126 public void detach() throws IOException { 127 synchronized (this) { 128 if (this.path != null) { 129 this.path = null; 130 } 131 } 132 } 133 134 // protocol version 135 private final static String PROTOCOL_VERSION = "1"; 136 137 // known errors 138 private final static int ATTACH_ERROR_BADVERSION = 101; 139 140 /** 141 * Execute the given command in the target VM. 142 */ 143 InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException { 144 assert args.length <= 3; // includes null 145 146 // did we detach? 147 String p; 148 synchronized (this) { 149 if (this.path == null) { 150 throw new IOException("Detached from target VM"); 151 } 152 p = this.path; 153 } 154 155 // create UNIX socket 156 int s = socket(); 157 158 // connect to target VM 159 try { 160 connect(s, p); 161 } catch (IOException x) { 162 close(s); 163 throw x; 164 } 165 166 IOException ioe = null; 167 168 // connected - write request 169 // <ver> <cmd> <args...> 170 try { 171 writeString(s, PROTOCOL_VERSION); 172 writeString(s, cmd); 173 174 for (int i=0; i<3; i++) { 175 if (i < args.length && args[i] != null) { 176 writeString(s, (String)args[i]); 177 } else { 178 writeString(s, ""); 179 } 180 } 181 } catch (IOException x) { 182 ioe = x; 183 } 184 185 186 // Create an input stream to read reply 187 SocketInputStream sis = new SocketInputStream(s); 188 189 // Read the command completion status 190 int completionStatus; 191 try { 192 completionStatus = readInt(sis); 193 } catch (IOException x) { 194 sis.close(); 195 if (ioe != null) { 196 throw ioe; 197 } else { 198 throw x; 199 } 200 } 201 202 if (completionStatus != 0) { 203 // read from the stream and use that as the error message 204 String message = readErrorMessage(sis); 205 sis.close(); 206 207 // In the event of a protocol mismatch then the target VM 208 // returns a known error so that we can throw a reasonable 209 // error. 210 if (completionStatus == ATTACH_ERROR_BADVERSION) { 211 throw new IOException("Protocol mismatch with target VM"); 212 } 213 214 // Special-case the "load" command so that the right exception is 215 // thrown. 216 if (cmd.equals("load")) { 217 String msg = "Failed to load agent library"; 218 if (!message.isEmpty()) 219 msg += ": " + message; 220 throw new AgentLoadException(msg); 221 } else { 222 if (message.isEmpty()) 223 message = "Command failed in target VM"; 224 throw new AttachOperationFailedException(message); 225 } 226 } 227 228 // Return the input stream so that the command output can be read 229 return sis; 230 } 231 232 /* 233 * InputStream for the socket connection to get target VM 234 */ 235 private class SocketInputStream extends InputStream { 236 int s; 237 238 public SocketInputStream(int s) { 239 this.s = s; 240 } 241 242 public synchronized int read() throws IOException { 243 byte b[] = new byte[1]; 244 int n = this.read(b, 0, 1); 245 if (n == 1) { 246 return b[0] & 0xff; 247 } else { 248 return -1; 249 } 250 } 251 252 public synchronized int read(byte[] bs, int off, int len) throws IOException { 253 if ((off < 0) || (off > bs.length) || (len < 0) || 254 ((off + len) > bs.length) || ((off + len) < 0)) { 255 throw new IndexOutOfBoundsException(); 256 } else if (len == 0) 257 return 0; 258 259 return VirtualMachineImpl.read(s, bs, off, len); 260 } 261 262 public void close() throws IOException { 263 VirtualMachineImpl.close(s); 264 } 265 } 266 267 // Return the socket file for the given process. 268 private String findSocketFile(int pid) { 269 File f = new File(tmpdir, ".java_pid" + pid); 270 if (!f.exists()) { 271 return null; 272 } 273 return f.getPath(); 274 } 275 276 // On Solaris/Linux/Aix a simple handshake is used to start the attach mechanism 277 // if not already started. The client creates a .attach_pid<pid> file in the 278 // target VM's working directory (or temp directory), and the SIGQUIT handler 279 // checks for the file. 280 private File createAttachFile(int pid) throws IOException { 281 String fn = ".attach_pid" + pid; 282 String path = "/proc/" + pid + "/cwd/" + fn; 283 File f = new File(path); 284 try { 285 f.createNewFile(); 286 } catch (IOException x) { 287 f = new File(tmpdir, fn); 288 f.createNewFile(); 289 } 290 return f; 291 } 292 293 /* 294 * Write/sends the given to the target VM. String is transmitted in 295 * UTF-8 encoding. 296 */ 297 private void writeString(int fd, String s) throws IOException { 298 if (s.length() > 0) { 299 byte b[]; 300 try { 301 b = s.getBytes("UTF-8"); 302 } catch (java.io.UnsupportedEncodingException x) { 303 throw new InternalError(x); 304 } 305 VirtualMachineImpl.write(fd, b, 0, b.length); 306 } 307 byte b[] = new byte[1]; 308 b[0] = 0; 309 write(fd, b, 0, 1); 310 } 311 312 313 //-- native methods 314 315 static native void sendQuitTo(int pid) throws IOException; 316 317 static native void checkPermissions(String path) throws IOException; 318 319 static native int socket() throws IOException; 320 321 static native void connect(int fd, String path) throws IOException; 322 323 static native void close(int fd) throws IOException; 324 325 static native int read(int fd, byte buf[], int off, int bufLen) throws IOException; 326 327 static native void write(int fd, byte buf[], int off, int bufLen) throws IOException; 328 329 static { 330 System.loadLibrary("attach"); 331 } 332} 333