1 /* 2 * Copyright (c) 2005, 2019, 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 "precompiled.hpp" 26 #include "runtime/interfaceSupport.hpp" 27 #include "runtime/os.hpp" 28 #include "services/attachListener.hpp" 29 #include "services/dtraceAttacher.hpp" 30 31 #include <windows.h> 32 #include <signal.h> // SIGBREAK 33 34 // The AttachListener thread services a queue of operations. It blocks in the dequeue 35 // function until an operation is enqueued. A client enqueues an operation by creating 36 // a thread in this process using the Win32 CreateRemoteThread function. That thread 37 // executes a small stub generated by the client. The stub invokes the 38 // JVM_EnqueueOperation function which checks the operation parameters and enqueues 39 // the operation to the queue serviced by the attach listener. The thread created by 40 // the client is a native thread and is restricted to a single page of stack. To keep 41 // it simple operations are pre-allocated at initialization time. An enqueue thus 42 // takes a preallocated operation, populates the operation parameters, adds it to 43 // queue and wakes up the attach listener. 44 // 45 // When an operation has completed the attach listener is required to send the 46 // operation result and any result data to the client. In this implementation the 47 // client is a pipe server. In the enqueue operation it provides the name of pipe 48 // to this process. When the operation is completed this process opens the pipe and 49 // sends the result and output back to the client. Note that writing to the pipe 50 // (and flushing the output) is a blocking operation. This means that a non-responsive 51 // client could potentially hang the attach listener thread indefinitely. In that 52 // case no new operations would be executed but the VM would continue as normal. 53 // As only suitably privileged processes can open this process we concluded that 54 // this wasn't worth worrying about. 55 56 57 // forward reference 58 class Win32AttachOperation; 59 60 61 class Win32AttachListener: AllStatic { 62 private: 63 enum { 64 preallocate_count = 4 // number of preallocated operations 65 }; 66 67 // protects the preallocated list and the operation list 68 static HANDLE _mutex; 69 70 // head of preallocated operations list 71 static Win32AttachOperation* _avail; 72 73 // head and tail of enqueue operations list 74 static Win32AttachOperation* _head; 75 static Win32AttachOperation* _tail; 76 77 78 static Win32AttachOperation* head() { return _head; } 79 static void set_head(Win32AttachOperation* head) { _head = head; } 80 81 static Win32AttachOperation* tail() { return _tail; } 82 static void set_tail(Win32AttachOperation* tail) { _tail = tail; } 83 84 85 // used to wakeup the listener 86 static HANDLE _wakeup; 87 static HANDLE wakeup() { return _wakeup; } 88 89 public: 90 enum { 91 ATTACH_ERROR_DISABLED = 100, // error codes 92 ATTACH_ERROR_RESOURCE = 101, 93 ATTACH_ERROR_ILLEGALARG = 102, 94 ATTACH_ERROR_INTERNAL = 103 95 }; 96 97 static int init(); 98 static HANDLE mutex() { return _mutex; } 99 100 static Win32AttachOperation* available() { return _avail; } 101 static void set_available(Win32AttachOperation* avail) { _avail = avail; } 102 103 // enqueue an operation to the end of the list 104 static int enqueue(char* cmd, char* arg1, char* arg2, char* arg3, char* pipename); 105 106 // dequeue an operation from from head of the list 107 static Win32AttachOperation* dequeue(); 108 }; 109 110 // statics 111 HANDLE Win32AttachListener::_mutex; 112 HANDLE Win32AttachListener::_wakeup; 113 Win32AttachOperation* Win32AttachListener::_avail; 114 Win32AttachOperation* Win32AttachListener::_head; 115 Win32AttachOperation* Win32AttachListener::_tail; 116 117 118 // Win32AttachOperation is an AttachOperation that additionally encapsulates the name 119 // of a pipe which is used to send the operation reply/output to the client. 120 // Win32AttachOperation can also be linked in a list. 121 122 class Win32AttachOperation: public AttachOperation { 123 private: 124 friend class Win32AttachListener; 125 126 enum { 127 pipe_name_max = 256 // maximum pipe name 128 }; 129 130 char _pipe[pipe_name_max+1]; 131 132 const char* pipe() const { return _pipe; } 133 void set_pipe(const char* pipe) { 134 assert(strlen(pipe) <= pipe_name_max, "execeds maximum length of pipe name"); 135 strcpy(_pipe, pipe); 136 } 137 138 HANDLE open_pipe(); 139 static BOOL write_pipe(HANDLE hPipe, char* buf, int len); 140 141 Win32AttachOperation* _next; 142 143 Win32AttachOperation* next() const { return _next; } 144 void set_next(Win32AttachOperation* next) { _next = next; } 145 146 // noarg constructor as operation is preallocated 147 Win32AttachOperation() : AttachOperation("<noname>") { 148 set_pipe("<nopipe>"); 149 set_next(NULL); 150 } 151 152 public: 153 void Win32AttachOperation::complete(jint result, bufferedStream* result_stream); 154 }; 155 156 157 // preallocate the required number of operations 158 int Win32AttachListener::init() { 159 _mutex = (void*)::CreateMutex(NULL, FALSE, NULL); 160 guarantee(_mutex != (HANDLE)NULL, "mutex creation failed"); 161 162 _wakeup = ::CreateSemaphore(NULL, 0, 1, NULL); 163 guarantee(_wakeup != (HANDLE)NULL, "semaphore creation failed"); 164 165 set_head(NULL); 166 set_tail(NULL); 167 168 // preallocate a few operations 169 set_available(NULL); 170 for (int i=0; i<preallocate_count; i++) { 171 Win32AttachOperation* op = new Win32AttachOperation(); 172 op->set_next(available()); 173 set_available(op); 174 } 175 176 return 0; 177 } 178 179 // Enqueue an operation. This is called from a native thread that is not attached to VM. 180 // Also we need to be careful not to execute anything that results in more than a 4k stack. 181 // 182 int Win32AttachListener::enqueue(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename) { 183 // listener not running 184 if (!AttachListener::is_initialized()) { 185 return ATTACH_ERROR_DISABLED; 186 } 187 188 // check that all paramteres to the operation 189 if (strlen(cmd) > AttachOperation::name_length_max) return ATTACH_ERROR_ILLEGALARG; 190 if (strlen(arg0) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG; 191 if (strlen(arg0) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG; 192 if (strlen(pipename) > Win32AttachOperation::pipe_name_max) return ATTACH_ERROR_ILLEGALARG; 193 194 // check for a well-formed pipename 195 if (strstr(pipename, "\\\\.\\pipe\\") != pipename) return ATTACH_ERROR_ILLEGALARG; 196 197 // grab the lock for the list 198 DWORD res = ::WaitForSingleObject(mutex(), INFINITE); 199 if (res != WAIT_OBJECT_0) { 200 return ATTACH_ERROR_INTERNAL; 201 } 202 203 // try to get an operation from the available list 204 Win32AttachOperation* op = available(); 205 if (op != NULL) { 206 set_available(op->next()); 207 208 // add to end (tail) of list 209 op->set_next(NULL); 210 if (tail() == NULL) { 211 set_head(op); 212 } else { 213 tail()->set_next(op); 214 } 215 set_tail(op); 216 217 op->set_name(cmd); 218 op->set_arg(0, arg0); 219 op->set_arg(1, arg1); 220 op->set_arg(2, arg2); 221 op->set_pipe(pipename); 222 223 // wakeup the thread waiting for operations 224 ::ReleaseSemaphore(wakeup(), 1, NULL); 225 } 226 ::ReleaseMutex(mutex()); 227 228 return (op != NULL) ? 0 : ATTACH_ERROR_RESOURCE; 229 } 230 231 232 // dequeue the operation from the head of the operation list. If 233 Win32AttachOperation* Win32AttachListener::dequeue() { 234 for (;;) { 235 DWORD res = ::WaitForSingleObject(wakeup(), INFINITE); 236 guarantee(res == WAIT_OBJECT_0, "wait failed"); 237 238 res = ::WaitForSingleObject(mutex(), INFINITE); 239 guarantee(res == WAIT_OBJECT_0, "wait failed"); 240 241 Win32AttachOperation* op = head(); 242 if (op != NULL) { 243 set_head(op->next()); 244 if (head() == NULL) { // list is empty 245 set_tail(NULL); 246 } 247 } 248 ::ReleaseMutex(mutex()); 249 250 if (op != NULL) { 251 return op; 252 } 253 } 254 } 255 256 257 // open the pipe to the client 258 HANDLE Win32AttachOperation::open_pipe() { 259 HANDLE hPipe; 260 261 hPipe = ::CreateFile( pipe(), // pipe name 262 GENERIC_WRITE, // write only 263 0, // no sharing 264 NULL, // default security attributes 265 OPEN_EXISTING, // opens existing pipe 266 0, // default attributes 267 NULL); // no template file 268 269 if (hPipe != INVALID_HANDLE_VALUE) { 270 // shouldn't happen as there is a pipe created per operation 271 if (::GetLastError() == ERROR_PIPE_BUSY) { 272 return INVALID_HANDLE_VALUE; 273 } 274 } 275 return hPipe; 276 } 277 278 // write to the pipe 279 BOOL Win32AttachOperation::write_pipe(HANDLE hPipe, char* buf, int len) { 280 do { 281 DWORD nwrote; 282 283 BOOL fSuccess = WriteFile( hPipe, // pipe handle 284 (LPCVOID)buf, // message 285 (DWORD)len, // message length 286 &nwrote, // bytes written 287 NULL); // not overlapped 288 if (!fSuccess) { 289 return fSuccess; 290 } 291 buf += nwrote; 292 len -= nwrote; 293 } 294 while (len > 0); 295 return TRUE; 296 } 297 298 // Complete the operation: 299 // - open the pipe to the client 300 // - write the operation result (a jint) 301 // - write the operation output (the result stream) 302 // 303 void Win32AttachOperation::complete(jint result, bufferedStream* result_stream) { 304 JavaThread* thread = JavaThread::current(); 305 ThreadBlockInVM tbivm(thread); 306 307 thread->set_suspend_equivalent(); 308 // cleared by handle_special_suspend_equivalent_condition() or 309 // java_suspend_self() via check_and_wait_while_suspended() 310 311 HANDLE hPipe = open_pipe(); 312 if (hPipe != INVALID_HANDLE_VALUE) { 313 BOOL fSuccess; 314 315 char msg[32]; 316 sprintf(msg, "%d\n", result); 317 318 fSuccess = write_pipe(hPipe, msg, (int)strlen(msg)); 319 if (fSuccess) { 320 write_pipe(hPipe, (char*) result_stream->base(), (int)(result_stream->size())); 321 } 322 323 // Need to flush buffers 324 FlushFileBuffers(hPipe); 325 CloseHandle(hPipe); 326 } 327 328 DWORD res = ::WaitForSingleObject(Win32AttachListener::mutex(), INFINITE); 329 if (res == WAIT_OBJECT_0) { 330 331 // put the operation back on the available list 332 set_next(Win32AttachListener::available()); 333 Win32AttachListener::set_available(this); 334 335 ::ReleaseMutex(Win32AttachListener::mutex()); 336 } 337 338 // were we externally suspended while we were waiting? 339 thread->check_and_wait_while_suspended(); 340 } 341 342 343 // AttachOperation functions 344 345 AttachOperation* AttachListener::dequeue() { 346 JavaThread* thread = JavaThread::current(); 347 ThreadBlockInVM tbivm(thread); 348 349 thread->set_suspend_equivalent(); 350 // cleared by handle_special_suspend_equivalent_condition() or 351 // java_suspend_self() via check_and_wait_while_suspended() 352 353 AttachOperation* op = Win32AttachListener::dequeue(); 354 355 // were we externally suspended while we were waiting? 356 thread->check_and_wait_while_suspended(); 357 358 return op; 359 } 360 361 void AttachListener::vm_start() { 362 // nothing to do 363 } 364 365 int AttachListener::pd_init() { 366 return Win32AttachListener::init(); 367 } 368 369 // This function is used for Un*x OSes only. 370 // We need not to implement it for Windows. 371 bool AttachListener::check_socket_file() { 372 return false; 373 } 374 375 // always startup on Windows NT/2000/XP 376 bool AttachListener::init_at_startup() { 377 return os::win32::is_nt(); 378 } 379 380 // no trigger mechanism on Windows to start Attach Listener lazily 381 bool AttachListener::is_init_trigger() { 382 return false; 383 } 384 385 void AttachListener::abort() { 386 // nothing to do 387 } 388 389 void AttachListener::pd_data_dump() { 390 os::signal_notify(SIGBREAK); 391 } 392 393 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) { 394 return NULL; 395 } 396 397 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) { 398 out->print_cr("flag '%s' cannot be changed", op->arg(0)); 399 return JNI_ERR; 400 } 401 402 void AttachListener::pd_detachall() { 403 // do nothing for now 404 } 405 406 // Native thread started by remote client executes this. 407 extern "C" { 408 JNIEXPORT jint JNICALL 409 JVM_EnqueueOperation(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename) { 410 return (jint)Win32AttachListener::enqueue(cmd, arg0, arg1, arg2, pipename); 411 } 412 413 } // extern