| /* |
| * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "runtime/interfaceSupport.hpp" |
| #include "runtime/os.hpp" |
| #include "services/attachListener.hpp" |
| #include "services/dtraceAttacher.hpp" |
| |
| #include <windows.h> |
| #include <signal.h> // SIGBREAK |
| #include <stdio.h> |
| |
| // The AttachListener thread services a queue of operations. It blocks in the dequeue |
| // function until an operation is enqueued. A client enqueues an operation by creating |
| // a thread in this process using the Win32 CreateRemoteThread function. That thread |
| // executes a small stub generated by the client. The stub invokes the |
| // JVM_EnqueueOperation function which checks the operation parameters and enqueues |
| // the operation to the queue serviced by the attach listener. The thread created by |
| // the client is a native thread and is restricted to a single page of stack. To keep |
| // it simple operations are pre-allocated at initialization time. An enqueue thus |
| // takes a preallocated operation, populates the operation parameters, adds it to |
| // queue and wakes up the attach listener. |
| // |
| // When an operation has completed the attach listener is required to send the |
| // operation result and any result data to the client. In this implementation the |
| // client is a pipe server. In the enqueue operation it provides the name of pipe |
| // to this process. When the operation is completed this process opens the pipe and |
| // sends the result and output back to the client. Note that writing to the pipe |
| // (and flushing the output) is a blocking operation. This means that a non-responsive |
| // client could potentially hang the attach listener thread indefinitely. In that |
| // case no new operations would be executed but the VM would continue as normal. |
| // As only suitably privileged processes can open this process we concluded that |
| // this wasn't worth worrying about. |
| |
| |
| // forward reference |
| class Win32AttachOperation; |
| |
| |
| class Win32AttachListener: AllStatic { |
| private: |
| enum { |
| max_enqueued_operations = 4 |
| }; |
| |
| // protects the preallocated list and the operation list |
| static HANDLE _mutex; |
| |
| // head of preallocated operations list |
| static Win32AttachOperation* _avail; |
| |
| // head and tail of enqueue operations list |
| static Win32AttachOperation* _head; |
| static Win32AttachOperation* _tail; |
| |
| |
| static Win32AttachOperation* head() { return _head; } |
| static void set_head(Win32AttachOperation* head) { _head = head; } |
| |
| static Win32AttachOperation* tail() { return _tail; } |
| static void set_tail(Win32AttachOperation* tail) { _tail = tail; } |
| |
| |
| // A semaphore is used for communication about enqueued operations. |
| // The maximum count for the semaphore object will be set to "max_enqueued_operations". |
| // The state of a semaphore is signaled when its count is greater than |
| // zero (there are operations enqueued), and nonsignaled when it is zero. |
| static HANDLE _enqueued_ops_semaphore; |
| static HANDLE enqueued_ops_semaphore() { return _enqueued_ops_semaphore; } |
| |
| public: |
| enum { |
| ATTACH_ERROR_DISABLED = 100, // error codes |
| ATTACH_ERROR_RESOURCE = 101, |
| ATTACH_ERROR_ILLEGALARG = 102, |
| ATTACH_ERROR_INTERNAL = 103 |
| }; |
| |
| static int init(); |
| static HANDLE mutex() { return _mutex; } |
| |
| static Win32AttachOperation* available() { return _avail; } |
| static void set_available(Win32AttachOperation* avail) { _avail = avail; } |
| |
| // enqueue an operation to the end of the list |
| static int enqueue(char* cmd, char* arg1, char* arg2, char* arg3, char* pipename); |
| |
| // dequeue an operation from from head of the list |
| static Win32AttachOperation* dequeue(); |
| }; |
| |
| // statics |
| HANDLE Win32AttachListener::_mutex; |
| HANDLE Win32AttachListener::_enqueued_ops_semaphore; |
| Win32AttachOperation* Win32AttachListener::_avail; |
| Win32AttachOperation* Win32AttachListener::_head; |
| Win32AttachOperation* Win32AttachListener::_tail; |
| |
| |
| // Win32AttachOperation is an AttachOperation that additionally encapsulates the name |
| // of a pipe which is used to send the operation reply/output to the client. |
| // Win32AttachOperation can also be linked in a list. |
| |
| class Win32AttachOperation: public AttachOperation { |
| private: |
| friend class Win32AttachListener; |
| |
| enum { |
| pipe_name_max = 256 // maximum pipe name |
| }; |
| |
| char _pipe[pipe_name_max+1]; |
| |
| const char* pipe() const { return _pipe; } |
| void set_pipe(const char* pipe) { |
| assert(strlen(pipe) <= pipe_name_max, "execeds maximum length of pipe name"); |
| strcpy(_pipe, pipe); |
| } |
| |
| HANDLE open_pipe(); |
| static BOOL write_pipe(HANDLE hPipe, char* buf, int len); |
| |
| Win32AttachOperation* _next; |
| |
| Win32AttachOperation* next() const { return _next; } |
| void set_next(Win32AttachOperation* next) { _next = next; } |
| |
| // noarg constructor as operation is preallocated |
| Win32AttachOperation() : AttachOperation("<noname>") { |
| set_pipe("<nopipe>"); |
| set_next(NULL); |
| } |
| |
| public: |
| void Win32AttachOperation::complete(jint result, bufferedStream* result_stream); |
| }; |
| |
| |
| // Preallocate the maximum number of operations that can be enqueued. |
| int Win32AttachListener::init() { |
| _mutex = (void*)::CreateMutex(NULL, FALSE, NULL); |
| guarantee(_mutex != (HANDLE)NULL, "mutex creation failed"); |
| |
| _enqueued_ops_semaphore = ::CreateSemaphore(NULL, 0, max_enqueued_operations, NULL); |
| guarantee(_enqueued_ops_semaphore != (HANDLE)NULL, "semaphore creation failed"); |
| |
| set_head(NULL); |
| set_tail(NULL); |
| set_available(NULL); |
| |
| for (int i=0; i<max_enqueued_operations; i++) { |
| Win32AttachOperation* op = new Win32AttachOperation(); |
| op->set_next(available()); |
| set_available(op); |
| } |
| |
| return 0; |
| } |
| |
| // Enqueue an operation. This is called from a native thread that is not attached to VM. |
| // Also we need to be careful not to execute anything that results in more than a 4k stack. |
| // |
| int Win32AttachListener::enqueue(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename) { |
| // listener not running |
| if (!AttachListener::is_initialized()) { |
| return ATTACH_ERROR_DISABLED; |
| } |
| |
| // check that all paramteres to the operation |
| if (strlen(cmd) > AttachOperation::name_length_max) return ATTACH_ERROR_ILLEGALARG; |
| if (strlen(arg0) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG; |
| if (strlen(arg1) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG; |
| if (strlen(arg2) > AttachOperation::arg_length_max) return ATTACH_ERROR_ILLEGALARG; |
| if (strlen(pipename) > Win32AttachOperation::pipe_name_max) return ATTACH_ERROR_ILLEGALARG; |
| |
| // check for a well-formed pipename |
| if (strstr(pipename, "\\\\.\\pipe\\") != pipename) return ATTACH_ERROR_ILLEGALARG; |
| |
| // grab the lock for the list |
| DWORD res = ::WaitForSingleObject(mutex(), INFINITE); |
| if (res != WAIT_OBJECT_0) { |
| return ATTACH_ERROR_INTERNAL; |
| } |
| |
| // try to get an operation from the available list |
| Win32AttachOperation* op = available(); |
| if (op != NULL) { |
| set_available(op->next()); |
| |
| // add to end (tail) of list |
| op->set_next(NULL); |
| if (tail() == NULL) { |
| set_head(op); |
| } else { |
| tail()->set_next(op); |
| } |
| set_tail(op); |
| |
| op->set_name(cmd); |
| op->set_arg(0, arg0); |
| op->set_arg(1, arg1); |
| op->set_arg(2, arg2); |
| op->set_pipe(pipename); |
| |
| // Increment number of enqueued operations. |
| // Side effect: Semaphore will be signaled and will release |
| // any blocking waiters (i.e. the AttachListener thread). |
| BOOL not_exceeding_semaphore_maximum_count = |
| ::ReleaseSemaphore(enqueued_ops_semaphore(), 1, NULL); |
| guarantee(not_exceeding_semaphore_maximum_count, "invariant"); |
| } |
| ::ReleaseMutex(mutex()); |
| |
| return (op != NULL) ? 0 : ATTACH_ERROR_RESOURCE; |
| } |
| |
| |
| // dequeue the operation from the head of the operation list. |
| Win32AttachOperation* Win32AttachListener::dequeue() { |
| for (;;) { |
| DWORD res = ::WaitForSingleObject(enqueued_ops_semaphore(), INFINITE); |
| // returning from WaitForSingleObject will have decreased |
| // the current count of the semaphore by 1. |
| guarantee(res == WAIT_OBJECT_0, "wait failed"); |
| |
| res = ::WaitForSingleObject(mutex(), INFINITE); |
| guarantee(res == WAIT_OBJECT_0, "wait failed"); |
| |
| Win32AttachOperation* op = head(); |
| if (op != NULL) { |
| set_head(op->next()); |
| if (head() == NULL) { // list is empty |
| set_tail(NULL); |
| } |
| } |
| ::ReleaseMutex(mutex()); |
| |
| if (op != NULL) { |
| return op; |
| } |
| } |
| } |
| |
| |
| // open the pipe to the client |
| HANDLE Win32AttachOperation::open_pipe() { |
| HANDLE hPipe; |
| |
| hPipe = ::CreateFile( pipe(), // pipe name |
| GENERIC_WRITE, // write only |
| 0, // no sharing |
| NULL, // default security attributes |
| OPEN_EXISTING, // opens existing pipe |
| 0, // default attributes |
| NULL); // no template file |
| |
| if (hPipe != INVALID_HANDLE_VALUE) { |
| // shouldn't happen as there is a pipe created per operation |
| if (::GetLastError() == ERROR_PIPE_BUSY) { |
| ::CloseHandle(hPipe); |
| return INVALID_HANDLE_VALUE; |
| } |
| } |
| return hPipe; |
| } |
| |
| // write to the pipe |
| BOOL Win32AttachOperation::write_pipe(HANDLE hPipe, char* buf, int len) { |
| do { |
| DWORD nwrote; |
| |
| BOOL fSuccess = WriteFile( hPipe, // pipe handle |
| (LPCVOID)buf, // message |
| (DWORD)len, // message length |
| &nwrote, // bytes written |
| NULL); // not overlapped |
| if (!fSuccess) { |
| return fSuccess; |
| } |
| buf += nwrote; |
| len -= nwrote; |
| } |
| while (len > 0); |
| return TRUE; |
| } |
| |
| // Complete the operation: |
| // - open the pipe to the client |
| // - write the operation result (a jint) |
| // - write the operation output (the result stream) |
| // |
| void Win32AttachOperation::complete(jint result, bufferedStream* result_stream) { |
| JavaThread* thread = JavaThread::current(); |
| ThreadBlockInVM tbivm(thread); |
| |
| thread->set_suspend_equivalent(); |
| // cleared by handle_special_suspend_equivalent_condition() or |
| // java_suspend_self() via check_and_wait_while_suspended() |
| |
| HANDLE hPipe = open_pipe(); |
| if (hPipe != INVALID_HANDLE_VALUE) { |
| BOOL fSuccess; |
| |
| char msg[32]; |
| _snprintf(msg, sizeof(msg), "%d\n", result); |
| msg[sizeof(msg) - 1] = '\0'; |
| |
| fSuccess = write_pipe(hPipe, msg, (int)strlen(msg)); |
| if (fSuccess) { |
| write_pipe(hPipe, (char*) result_stream->base(), (int)(result_stream->size())); |
| } |
| |
| // Need to flush buffers |
| FlushFileBuffers(hPipe); |
| CloseHandle(hPipe); |
| } |
| |
| DWORD res = ::WaitForSingleObject(Win32AttachListener::mutex(), INFINITE); |
| if (res == WAIT_OBJECT_0) { |
| |
| // put the operation back on the available list |
| set_next(Win32AttachListener::available()); |
| Win32AttachListener::set_available(this); |
| |
| ::ReleaseMutex(Win32AttachListener::mutex()); |
| } |
| |
| // were we externally suspended while we were waiting? |
| thread->check_and_wait_while_suspended(); |
| } |
| |
| |
| // AttachOperation functions |
| |
| AttachOperation* AttachListener::dequeue() { |
| JavaThread* thread = JavaThread::current(); |
| ThreadBlockInVM tbivm(thread); |
| |
| thread->set_suspend_equivalent(); |
| // cleared by handle_special_suspend_equivalent_condition() or |
| // java_suspend_self() via check_and_wait_while_suspended() |
| |
| AttachOperation* op = Win32AttachListener::dequeue(); |
| |
| // were we externally suspended while we were waiting? |
| thread->check_and_wait_while_suspended(); |
| |
| return op; |
| } |
| |
| void AttachListener::vm_start() { |
| // nothing to do |
| } |
| |
| int AttachListener::pd_init() { |
| return Win32AttachListener::init(); |
| } |
| |
| bool AttachListener::init_at_startup() { |
| return true; |
| } |
| |
| // no trigger mechanism on Windows to start Attach Listener lazily |
| bool AttachListener::is_init_trigger() { |
| return false; |
| } |
| |
| void AttachListener::abort() { |
| // nothing to do |
| } |
| |
| void AttachListener::pd_data_dump() { |
| os::signal_notify(SIGBREAK); |
| } |
| |
| AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) { |
| return NULL; |
| } |
| |
| jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) { |
| out->print_cr("flag '%s' cannot be changed", op->arg(0)); |
| return JNI_ERR; |
| } |
| |
| void AttachListener::pd_detachall() { |
| // do nothing for now |
| } |
| |
| // Native thread started by remote client executes this. |
| extern "C" { |
| JNIEXPORT jint JNICALL |
| JVM_EnqueueOperation(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename) { |
| return (jint)Win32AttachListener::enqueue(cmd, arg0, arg1, arg2, pipename); |
| } |
| |
| } // extern |