1 /*
2 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
3 * Copyright 2013 SAP AG. 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 */
26 package sun.tools.attach;
27
28 import com.sun.tools.attach.AgentLoadException;
29 import com.sun.tools.attach.AttachNotSupportedException;
30 import com.sun.tools.attach.spi.AttachProvider;
31 import java.io.InputStream;
32 import java.io.IOException;
33 import java.io.File;
34
35 // Based on linux/classes/sun/tools/attach/VirtualMachineImpl.java.
36
37 /*
38 * Aix implementation of HotSpotVirtualMachine
39 */
40 public 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 // The patch to the socket file created by the target VM
49 String path;
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
59 // This provider only understands pids
60 int pid;
61 try {
62 pid = Integer.parseInt(vmid);
63 } catch (NumberFormatException x) {
64 throw new AttachNotSupportedException("Invalid process identifier");
65 }
66
67 // Find the socket file. If not found then we attempt to start the
68 // attach mechanism in the target VM by sending it a QUIT signal.
69 // Then we attempt to find the socket file again.
70 path = findSocketFile(pid);
71 if (path == null) {
72 File f = createAttachFile(pid);
73 try {
74 sendQuitTo(pid);
75
76 // give the target VM time to start the attach mechanism
77 int i = 0;
78 long delay = 200;
79 int retries = (int)(attachTimeout() / delay);
80 do {
81 try {
82 Thread.sleep(delay);
83 } catch (InterruptedException x) { }
84 path = findSocketFile(pid);
85 i++;
86 } while (i <= retries && path == null);
87 if (path == null) {
88 throw new AttachNotSupportedException(
89 "Unable to open socket file: target process not responding " +
90 "or HotSpot VM not loaded");
91 }
92 } finally {
93 f.delete();
94 }
95 }
96
97 // Check that the file owner/permission to avoid attaching to
98 // bogus process
99 checkPermissions(path);
100
101 // Check that we can connect to the process
102 // - this ensures we throw the permission denied error now rather than
103 // later when we attempt to enqueue a command.
104 int s = socket();
105 try {
106 connect(s, path);
107 } finally {
108 close(s);
109 }
110 }
111
112 /**
113 * Detach from the target VM
114 */
115 public void detach() throws IOException {
116 synchronized (this) {
117 if (this.path != null) {
118 this.path = null;
119 }
120 }
121 }
122
123 // protocol version
124 private final static String PROTOCOL_VERSION = "1";
125
126 // known errors
127 private final static int ATTACH_ERROR_BADVERSION = 101;
128
129 /**
130 * Execute the given command in the target VM.
131 */
132 InputStream execute(String cmd, Object ... args) throws AgentLoadException, IOException {
133 assert args.length <= 3; // includes null
134
135 // did we detach?
136 String p;
137 synchronized (this) {
138 if (this.path == null) {
139 throw new IOException("Detached from target VM");
140 }
141 p = this.path;
142 }
143
144 // create UNIX socket
145 int s = socket();
146
147 // connect to target VM
148 try {
149 connect(s, p);
150 } catch (IOException x) {
151 close(s);
152 throw x;
153 }
154
155 IOException ioe = null;
156
157 // connected - write request
158 // <ver> <cmd> <args...>
159 try {
160 writeString(s, PROTOCOL_VERSION);
161 writeString(s, cmd);
162
163 for (int i=0; i<3; i++) {
164 if (i < args.length && args[i] != null) {
165 writeString(s, (String)args[i]);
166 } else {
167 writeString(s, "");
168 }
169 }
170 } catch (IOException x) {
171 ioe = x;
172 }
173
174
175 // Create an input stream to read reply
176 SocketInputStream sis = new SocketInputStream(s);
177
178 // Read the command completion status
179 int completionStatus;
180 try {
181 completionStatus = readInt(sis);
182 } catch (IOException x) {
183 sis.close();
184 if (ioe != null) {
185 throw ioe;
186 } else {
187 throw x;
188 }
189 }
190
191 if (completionStatus != 0) {
192 sis.close();
193
194 // In the event of a protocol mismatch then the target VM
195 // returns a known error so that we can throw a reasonable
196 // error.
197 if (completionStatus == ATTACH_ERROR_BADVERSION) {
198 throw new IOException("Protocol mismatch with target VM");
199 }
200
201 // Special-case the "load" command so that the right exception is
202 // thrown.
203 if (cmd.equals("load")) {
204 throw new AgentLoadException("Failed to load agent library");
205 } else {
206 throw new IOException("Command failed in target VM");
207 }
208 }
209
210 // Return the input stream so that the command output can be read
211 return sis;
212 }
213
214 /*
215 * InputStream for the socket connection to get target VM
216 */
217 private class SocketInputStream extends InputStream {
218 int s;
219
220 public SocketInputStream(int s) {
221 this.s = s;
222 }
223
224 public synchronized int read() throws IOException {
225 byte b[] = new byte[1];
226 int n = this.read(b, 0, 1);
227 if (n == 1) {
228 return b[0] & 0xff;
229 } else {
230 return -1;
231 }
232 }
233
234 public synchronized int read(byte[] bs, int off, int len) throws IOException {
235 if ((off < 0) || (off > bs.length) || (len < 0) ||
236 ((off + len) > bs.length) || ((off + len) < 0)) {
237 throw new IndexOutOfBoundsException();
238 } else if (len == 0)
239 return 0;
240
241 return VirtualMachineImpl.read(s, bs, off, len);
242 }
243
244 public void close() throws IOException {
245 VirtualMachineImpl.close(s);
246 }
247 }
248
249 // Return the socket file for the given process.
250 private String findSocketFile(int pid) {
251 File f = new File(tmpdir, ".java_pid" + pid);
252 if (!f.exists()) {
253 return null;
254 }
255 return f.getPath();
256 }
257
258 // On Solaris/Linux/Aix a simple handshake is used to start the attach mechanism
259 // if not already started. The client creates a .attach_pid<pid> file in the
260 // target VM's working directory (or temp directory), and the SIGQUIT handler
261 // checks for the file.
262 private File createAttachFile(int pid) throws IOException {
263 String fn = ".attach_pid" + pid;
264 String path = "/proc/" + pid + "/cwd/" + fn;
265 File f = new File(path);
266 try {
267 f.createNewFile();
268 } catch (IOException x) {
269 f = new File(tmpdir, fn);
270 f.createNewFile();
271 }
272 return f;
273 }
274
275 /*
276 * Write/sends the given to the target VM. String is transmitted in
277 * UTF-8 encoding.
278 */
279 private void writeString(int fd, String s) throws IOException {
280 if (s.length() > 0) {
281 byte b[];
282 try {
283 b = s.getBytes("UTF-8");
284 } catch (java.io.UnsupportedEncodingException x) {
285 throw new InternalError(x);
286 }
287 VirtualMachineImpl.write(fd, b, 0, b.length);
288 }
289 byte b[] = new byte[1];
290 b[0] = 0;
291 write(fd, b, 0, 1);
292 }
293
294
295 //-- native methods
296
297 static native void sendQuitTo(int pid) throws IOException;
298
299 static native void checkPermissions(String path) throws IOException;
300
301 static native int socket() throws IOException;
302
303 static native void connect(int fd, String path) throws IOException;
304
305 static native void close(int fd) throws IOException;
306
307 static native int read(int fd, byte buf[], int off, int bufLen) throws IOException;
308
309 static native void write(int fd, byte buf[], int off, int bufLen) throws IOException;
310
311 static {
312 System.loadLibrary("attach");
313 }
314 }