1 /*
2 * Copyright (c) 2005, 2017, 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 VirtualMachineImpl 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 String socket_name;
49
50 /**
51 * Attaches to the target VM
52 */
53 VirtualMachineImpl(AttachProvider provider, String vmid)
54 throws AttachNotSupportedException, IOException
55 {
56 super(provider, vmid);
57
58 // This provider only understands 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 // Find the socket file. If not found then we attempt to start the
67 // attach mechanism in the target VM by sending it a QUIT signal.
68 // Then we attempt to find the socket file again.
69 File path = new File(tmpdir, ".java_pid" + pid);
70 socket_name = path.getPath();
71 if (!path.exists()) {
72 File f = createAttachFile(pid);
73 try {
74 sendQuitTo(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
88 time_spend += delay;
89 if (time_spend > timeout/2 && !path.exists()) {
90 // Send QUIT again to give target VM the last chance to react
91 sendQuitTo(pid);
92 }
93 } while (time_spend <= timeout && !path.exists());
94 if (!path.exists()) {
95 throw new AttachNotSupportedException(
96 String.format("Unable to open socket file %s: " +
97 "target process %d doesn't respond within %dms " +
98 "or HotSpot VM not loaded", socket_name,
99 pid, time_spend));
100 }
101 } finally {
102 f.delete();
103 }
104 }
105
106 // Check that the file owner/permission to avoid attaching to
107 // bogus process
108 checkPermissions(socket_name);
109
110 // Check that we can connect to the process
111 // - this ensures we throw the permission denied error now rather than
112 // later when we attempt to enqueue a command.
113 int s = socket();
114 try {
115 connect(s, socket_name);
116 } finally {
117 close(s);
118 }
119 }
120
121 /**
122 * Detach from the target VM
123 */
124 public void detach() throws IOException {
125 synchronized (this) {
126 if (this.path != null) {
127 this.path = null;
128 }
129 }
130 }
131
132 // protocol version
133 private final static String PROTOCOL_VERSION = "1";
134
135 // known errors
136 private final static int ATTACH_ERROR_BADVERSION = 101;
137
138 /**
139 * Execute the given command in the target VM.
140 */
141 InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException {
142 assert args.length <= 3; // includes null
143
144 // did we detach?
145 String p;
146 synchronized (this) {
147 if (this.path == null) {
148 throw new IOException("Detached from target VM");
149 }
150 p = this.path;
151 }
152
153 // create UNIX socket
154 int s = socket();
155
156 // connect to target VM
157 try {
158 connect(s, p);
159 } catch (IOException x) {
160 close(s);
161 throw x;
162 }
163
164 IOException ioe = null;
165
166 // connected - write request
167 // <ver> <cmd> <args...>
168 try {
169 writeString(s, PROTOCOL_VERSION);
170 writeString(s, cmd);
171
172 for (int i=0; i<3; i++) {
173 if (i < args.length && args[i] != null) {
174 writeString(s, (String)args[i]);
175 } else {
176 writeString(s, "");
177 }
178 }
179 } catch (IOException x) {
180 ioe = x;
181 }
182
183
184 // Create an input stream to read reply
185 SocketInputStream sis = new SocketInputStream(s);
186
187 // Read the command completion status
188 int completionStatus;
189 try {
190 completionStatus = readInt(sis);
191 } catch (IOException x) {
192 sis.close();
193 if (ioe != null) {
194 throw ioe;
195 } else {
196 throw x;
197 }
198 }
199
200 if (completionStatus != 0) {
201 // read from the stream and use that as the error message
202 String message = readErrorMessage(sis);
203 sis.close();
204
205 // In the event of a protocol mismatch then the target VM
206 // returns a known error so that we can throw a reasonable
207 // error.
208 if (completionStatus == ATTACH_ERROR_BADVERSION) {
209 throw new IOException("Protocol mismatch with target VM");
210 }
211
212 // Special-case the "load" command so that the right exception is
213 // thrown.
214 if (cmd.equals("load")) {
215 String msg = "Failed to load agent library";
216 if (!message.isEmpty())
217 msg += ": " + message;
218 throw new AgentLoadException(msg);
219 } else {
220 if (message.isEmpty())
221 message = "Command failed in target VM";
222 throw new AttachOperationFailedException(message);
223 }
224 }
225
226 // Return the input stream so that the command output can be read
227 return sis;
228 }
229
230 /*
231 * InputStream for the socket connection to get target VM
232 */
233 private class SocketInputStream extends InputStream {
234 int s;
235
236 public SocketInputStream(int s) {
237 this.s = s;
238 }
239
240 public synchronized int read() throws IOException {
241 byte b[] = new byte[1];
242 int n = this.read(b, 0, 1);
243 if (n == 1) {
244 return b[0] & 0xff;
245 } else {
246 return -1;
247 }
248 }
249
250 public synchronized int read(byte[] bs, int off, int len) throws IOException {
251 if ((off < 0) || (off > bs.length) || (len < 0) ||
252 ((off + len) > bs.length) || ((off + len) < 0)) {
253 throw new IndexOutOfBoundsException();
254 } else if (len == 0) {
255 return 0;
256 }
257
258 return VirtualMachineImpl.read(s, bs, off, len);
259 }
260
261 public void close() throws IOException {
262 VirtualMachineImpl.close(s);
263 }
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(x);
277 }
278 VirtualMachineImpl.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 private File createAttachFile(int pid) throws IOException {
286 String fn = ".attach_pid" + pid;
287 File f = new File(tmpdir, fn);
288 createAttachFile0(f.getPath());
289 return f;
290 }
291
292 //-- native methods
293
294 static native void sendQuitTo(int pid) throws IOException;
295
296 static native void checkPermissions(String path) throws IOException;
297
298 static native int socket() throws IOException;
299
300 static native void connect(int fd, String path) throws IOException;
301
302 static native void close(int fd) throws IOException;
303
304 static native int read(int fd, byte buf[], int off, int bufLen) throws IOException;
305
306 static native void write(int fd, byte buf[], int off, int bufLen) throws IOException;
307
308 static native void createAttachFile0(String path);
309
310 static native String getTempDir();
311
312 static {
313 System.loadLibrary("attach");
314 tmpdir = getTempDir();
315 }
316 }