1 /*
2 * Copyright (c) 2005, 2006, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_attachListener_windows.cpp.incl"
27
28 #include <windows.h>
29 #include <signal.h> // SIGBREAK
30
31 // The AttachListener thread services a queue of operations. It blocks in the dequeue
32 // function until an operation is enqueued. A client enqueues an operation by creating
33 // a thread in this process using the Win32 CreateRemoteThread function. That thread
34 // executes a small stub generated by the client. The stub invokes the
35 // JVM_EnqueueOperation function which checks the operation parameters and enqueues
36 // the operation to the queue serviced by the attach listener. The thread created by
37 // the client is a native thread and is restricted to a single page of stack. To keep
38 // it simple operations are pre-allocated at initialization time. An enqueue thus
39 // takes a preallocated operation, populates the operation parameters, adds it to
40 // queue and wakes up the attach listener.
41 //
42 // When an operation has completed the attach listener is required to send the
43 // operation result and any result data to the client. In this implementation the
44 // client is a pipe server. In the enqueue operation it provides the name of pipe
45 // to this process. When the operation is completed this process opens the pipe and
46 // sends the result and output back to the client. Note that writing to the pipe
47 // (and flushing the output) is a blocking operation. This means that a non-responsive
48 // client could potentially hang the attach listener thread indefinitely. In that
49 // case no new operations would be executed but the VM would continue as normal.
50 // As only suitably privileged processes can open this process we concluded that
51 // this wasn't worth worrying about.
52
53
54 // forward reference
55 class Win32AttachOperation;
56
57
58 class Win32AttachListener: AllStatic {
59 private:
60 enum {
61 preallocate_count = 4 // number of preallocated operations
62 };
63
64 // protects the preallocated list and the operation list
65 static HANDLE _mutex;
66
67 // head of preallocated operations list
68 static Win32AttachOperation* _avail;
69
70 // head and tail of enqueue operations list
71 static Win32AttachOperation* _head;
72 static Win32AttachOperation* _tail;
73
74
75 static Win32AttachOperation* head() { return _head; }
76 static void set_head(Win32AttachOperation* head) { _head = head; }
77
78 static Win32AttachOperation* tail() { return _tail; }
79 static void set_tail(Win32AttachOperation* tail) { _tail = tail; }
80
81
82 // used to wakeup the listener
83 static HANDLE _wakeup;
84 static HANDLE wakeup() { return _wakeup; }
85
86 public:
87 enum {
88 ATTACH_ERROR_DISABLED = 100, // error codes
89 ATTACH_ERROR_RESOURCE = 101,
90 ATTACH_ERROR_ILLEGALARG = 102,
91 ATTACH_ERROR_INTERNAL = 103
92 };
93
94 static int init();
95 static HANDLE mutex() { return _mutex; }
96
97 static Win32AttachOperation* available() { return _avail; }
98 static void set_available(Win32AttachOperation* avail) { _avail = avail; }
99
100 // enqueue an operation to the end of the list
101 static int enqueue(char* cmd, char* arg1, char* arg2, char* arg3, char* pipename);
102
103 // dequeue an operation from from head of the list
104 static Win32AttachOperation* dequeue();
105 };
106
107 // statics
108 HANDLE Win32AttachListener::_mutex;
109 HANDLE Win32AttachListener::_wakeup;
110 Win32AttachOperation* Win32AttachListener::_avail;
111 Win32AttachOperation* Win32AttachListener::_head;
112 Win32AttachOperation* Win32AttachListener::_tail;
113
114
115 // Win32AttachOperation is an AttachOperation that additionally encapsulates the name
116 // of a pipe which is used to send the operation reply/output to the client.
117 // Win32AttachOperation can also be linked in a list.
118
119 class Win32AttachOperation: public AttachOperation {
120 private:
121 friend class Win32AttachListener;
122
123 enum {
124 pipe_name_max = 256 // maximum pipe name
125 };
126
127 char _pipe[pipe_name_max+1];
128
129 const char* pipe() const { return _pipe; }
130 void set_pipe(const char* pipe) {
131 assert(strlen(pipe) <= pipe_name_max, "execeds maximum length of pipe name");
132 strcpy(_pipe, pipe);
133 }
134
135 HANDLE open_pipe();
136 static BOOL write_pipe(HANDLE hPipe, char* buf, int len);
137
138 Win32AttachOperation* _next;
139
140 Win32AttachOperation* next() const { return _next; }
141 void set_next(Win32AttachOperation* next) { _next = next; }
142
143 // noarg constructor as operation is preallocated
144 Win32AttachOperation() : AttachOperation("<noname>") {
145 set_pipe("<nopipe>");
146 set_next(NULL);
147 }
148
149 public:
150 void Win32AttachOperation::complete(jint result, bufferedStream* result_stream);
151 };
152
153
154 // preallocate the required number of operations
155 int Win32AttachListener::init() {
156 _mutex = (void*)::CreateMutex(NULL, FALSE, NULL);
157 guarantee(_mutex != (HANDLE)NULL, "mutex creation failed");
158
159 _wakeup = ::CreateSemaphore(NULL, 0, 1, NULL);
160 guarantee(_wakeup != (HANDLE)NULL, "semaphore creation failed");
161
162 set_head(NULL);
163 set_tail(NULL);
164
165 // preallocate a few operations
166 set_available(NULL);
167 for (int i=0; i<preallocate_count; i++) {
168 Win32AttachOperation* op = new Win32AttachOperation();
169 op->set_next(available());
170 set_available(op);
171 }
172
173 return 0;
174 }
175
176 // Enqueue an operation. This is called from a native thread that is not attached to VM.
177 // Also we need to be careful not to execute anything that results in more than a 4k stack.
178 //
179 int Win32AttachListener::enqueue(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename) {
180 // listener not running
181 if (!AttachListener::is_initialized()) {
182 return ATTACH_ERROR_DISABLED;
183 }
184
185 // check that all paramteres to the operation
186 if (strlen(cmd) > AttachOperation::name_length_max) return ATTACH_ERROR_ILLEGALARG;
187 if (strlen(arg0) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG;
188 if (strlen(arg0) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG;
189 if (strlen(pipename) > Win32AttachOperation::pipe_name_max) return ATTACH_ERROR_ILLEGALARG;
190
191 // check for a well-formed pipename
192 if (strstr(pipename, "\\\\.\\pipe\\") != pipename) return ATTACH_ERROR_ILLEGALARG;
193
194 // grab the lock for the list
195 DWORD res = ::WaitForSingleObject(mutex(), INFINITE);
196 if (res != WAIT_OBJECT_0) {
197 return ATTACH_ERROR_INTERNAL;
198 }
199
200 // try to get an operation from the available list
201 Win32AttachOperation* op = available();
202 if (op != NULL) {
203 set_available(op->next());
204
205 // add to end (tail) of list
206 op->set_next(NULL);
207 if (tail() == NULL) {
208 set_head(op);
209 } else {
210 tail()->set_next(op);
211 }
212 set_tail(op);
213
214 op->set_name(cmd);
215 op->set_arg(0, arg0);
216 op->set_arg(1, arg1);
217 op->set_arg(2, arg2);
218 op->set_pipe(pipename);
219
220 // wakeup the thread waiting for operations
221 ::ReleaseSemaphore(wakeup(), 1, NULL);
222 }
223 ::ReleaseMutex(mutex());
224
225 return (op != NULL) ? 0 : ATTACH_ERROR_RESOURCE;
226 }
227
228
229 // dequeue the operation from the head of the operation list. If
230 Win32AttachOperation* Win32AttachListener::dequeue() {
231 for (;;) {
232 DWORD res = ::WaitForSingleObject(wakeup(), INFINITE);
233 guarantee(res == WAIT_OBJECT_0, "wait failed");
234
235 res = ::WaitForSingleObject(mutex(), INFINITE);
236 guarantee(res == WAIT_OBJECT_0, "wait failed");
237
238 Win32AttachOperation* op = head();
239 if (op != NULL) {
240 set_head(op->next());
241 if (head() == NULL) { // list is empty
242 set_tail(NULL);
243 }
244 }
245 ::ReleaseMutex(mutex());
246
247 if (op != NULL) {
248 return op;
249 }
250 }
251 }
252
253
254 // open the pipe to the client
255 HANDLE Win32AttachOperation::open_pipe() {
256 HANDLE hPipe;
257
258 hPipe = ::CreateFile( pipe(), // pipe name
259 GENERIC_WRITE, // write only
260 0, // no sharing
261 NULL, // default security attributes
262 OPEN_EXISTING, // opens existing pipe
263 0, // default attributes
264 NULL); // no template file
265
266 if (hPipe != INVALID_HANDLE_VALUE) {
267 // shouldn't happen as there is a pipe created per operation
268 if (::GetLastError() == ERROR_PIPE_BUSY) {
269 return INVALID_HANDLE_VALUE;
270 }
271 }
272 return hPipe;
273 }
274
275 // write to the pipe
276 BOOL Win32AttachOperation::write_pipe(HANDLE hPipe, char* buf, int len) {
277 do {
278 DWORD nwrote;
279
280 BOOL fSuccess = WriteFile( hPipe, // pipe handle
281 (LPCVOID)buf, // message
282 (DWORD)len, // message length
283 &nwrote, // bytes written
284 NULL); // not overlapped
285 if (!fSuccess) {
286 return fSuccess;
287 }
288 buf += nwrote;
289 len -= nwrote;
290 }
291 while (len > 0);
292 return TRUE;
293 }
294
295 // Complete the operation:
296 // - open the pipe to the client
297 // - write the operation result (a jint)
298 // - write the operation output (the result stream)
299 //
300 void Win32AttachOperation::complete(jint result, bufferedStream* result_stream) {
301 JavaThread* thread = JavaThread::current();
302 ThreadBlockInVM tbivm(thread);
303
304 thread->set_suspend_equivalent();
305 // cleared by handle_special_suspend_equivalent_condition() or
306 // java_suspend_self() via check_and_wait_while_suspended()
307
308 HANDLE hPipe = open_pipe();
309 if (hPipe != INVALID_HANDLE_VALUE) {
310 BOOL fSuccess;
311
312 char msg[32];
313 sprintf(msg, "%d\n", result);
314
315 fSuccess = write_pipe(hPipe, msg, (int)strlen(msg));
316 if (fSuccess) {
317 write_pipe(hPipe, (char*) result_stream->base(), (int)(result_stream->size()));
318 }
319
320 // Need to flush buffers
321 FlushFileBuffers(hPipe);
322 CloseHandle(hPipe);
323 }
324
325 DWORD res = ::WaitForSingleObject(Win32AttachListener::mutex(), INFINITE);
326 if (res == WAIT_OBJECT_0) {
327
328 // put the operation back on the available list
329 set_next(Win32AttachListener::available());
330 Win32AttachListener::set_available(this);
331
332 ::ReleaseMutex(Win32AttachListener::mutex());
333 }
334
335 // were we externally suspended while we were waiting?
336 thread->check_and_wait_while_suspended();
337 }
338
339
340 // AttachOperation functions
341
342 AttachOperation* AttachListener::dequeue() {
343 JavaThread* thread = JavaThread::current();
344 ThreadBlockInVM tbivm(thread);
345
346 thread->set_suspend_equivalent();
347 // cleared by handle_special_suspend_equivalent_condition() or
348 // java_suspend_self() via check_and_wait_while_suspended()
349
350 AttachOperation* op = Win32AttachListener::dequeue();
351
352 // were we externally suspended while we were waiting?
353 thread->check_and_wait_while_suspended();
354
355 return op;
356 }
357
358 int AttachListener::pd_init() {
359 return Win32AttachListener::init();
360 }
361
362 // always startup on Windows NT/2000/XP
363 bool AttachListener::init_at_startup() {
364 return os::win32::is_nt();
365 }
366
367 // no trigger mechanism on Windows to start Attach Listener lazily
368 bool AttachListener::is_init_trigger() {
369 return false;
370 }
371
372 void AttachListener::abort() {
373 // nothing to do
374 }
375
376 void AttachListener::pd_data_dump() {
377 os::signal_notify(SIGBREAK);
378 }
379
380 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) {
381 return NULL;
382 }
383
384 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
385 out->print_cr("flag '%s' cannot be changed", op->arg(0));
386 return JNI_ERR;
387 }
388
389 void AttachListener::pd_detachall() {
390 // do nothing for now
391 }
392
393 // Native thread started by remote client executes this.
394 extern "C" {
395 JNIEXPORT jint JNICALL
396 JVM_EnqueueOperation(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename) {
397 return (jint)Win32AttachListener::enqueue(cmd, arg0, arg1, arg2, pipename);
398 }
399
400 } // extern