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 */
26 package sun.tools.attach;
27
28 import com.sun.tools.attach.AttachOperationFailedException;
29 import com.sun.tools.attach.AgentLoadException;
30 import com.sun.tools.attach.AttachNotSupportedException;
31 import com.sun.tools.attach.spi.AttachProvider;
32
33 import java.io.InputStream;
34 import java.io.IOException;
35 import java.io.File;
36
37 // Based on linux/classes/sun/tools/attach/VirtualMachineImpl.java.
38
39 /*
40 * Aix implementation of HotSpotVirtualMachine
41 */
42 public 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 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 return VirtualMachineImpl.read(s, bs, off, len);
250 }
251
252 public void close() throws IOException {
253 VirtualMachineImpl.close(s);
254 }
255 }
256
257 // Return the socket file for the given process.
258 private String findSocketFile(int pid) {
259 File f = new File(tmpdir, ".java_pid" + pid);
260 if (!f.exists()) {
261 return null;
262 }
263 return f.getPath();
264 }
265
266 // On Solaris/Linux/Aix a simple handshake is used to start the attach mechanism
267 // if not already started. The client creates a .attach_pid<pid> file in the
268 // target VM's working directory (or temp directory), and the SIGQUIT handler
269 // checks for the file.
270 private File createAttachFile(int pid) throws IOException {
271 String fn = ".attach_pid" + pid;
272 String path = "/proc/" + pid + "/cwd/" + fn;
273 File f = new File(path);
274 try {
275 f.createNewFile();
276 } catch (IOException x) {
277 f = new File(tmpdir, fn);
278 f.createNewFile();
279 }
280 return f;
281 }
282
283 /*
284 * Write/sends the given to the target VM. String is transmitted in
285 * UTF-8 encoding.
286 */
287 private void writeString(int fd, String s) throws IOException {
288 if (s.length() > 0) {
289 byte b[];
290 try {
291 b = s.getBytes("UTF-8");
292 } catch (java.io.UnsupportedEncodingException x) {
293 throw new InternalError(x);
294 }
295 VirtualMachineImpl.write(fd, b, 0, b.length);
296 }
297 byte b[] = new byte[1];
298 b[0] = 0;
299 write(fd, b, 0, 1);
300 }
301
302
303 //-- native methods
304
305 static native void sendQuitTo(int pid) throws IOException;
306
307 static native void checkPermissions(String path) throws IOException;
308
309 static native int socket() throws IOException;
310
311 static native void connect(int fd, String path) throws IOException;
312
313 static native void close(int fd) throws IOException;
314
315 static native int read(int fd, byte buf[], int off, int bufLen) throws IOException;
316
317 static native void write(int fd, byte buf[], int off, int bufLen) throws IOException;
318
319 static {
320 System.loadLibrary("attach");
321 }
322 }