1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include <dlfcn.h>
18 #include <iostream>
19 
20 #include "base/casts.h"
21 #include "base/macros.h"
22 #include "jni/java_vm_ext.h"
23 #include "jni/jni_env_ext.h"
24 #include "thread-current-inl.h"
25 
26 namespace art {
27 namespace {
28 
29 static volatile std::atomic<bool> vm_was_shutdown(false);
30 static const int kThreadCount = 4;
31 
32 static std::atomic<int> barrier_count(kThreadCount + 1);
33 
JniThreadBarrierWait()34 static void JniThreadBarrierWait() {
35   barrier_count--;
36   while (barrier_count.load() != 0) {
37     usleep(1000);
38   }
39 }
40 
Java_Main_waitAndCallIntoJniEnv(JNIEnv * env,jclass)41 extern "C" JNIEXPORT void JNICALL Java_Main_waitAndCallIntoJniEnv(JNIEnv* env, jclass) {
42   // Wait for all threads to enter JNI together.
43   JniThreadBarrierWait();
44   // Wait until the runtime is shutdown.
45   while (!vm_was_shutdown.load()) {
46     usleep(1000);
47   }
48   std::cout << "About to call exception check\n";
49   env->ExceptionCheck();
50   LOG(ERROR) << "Should not be reached!";
51 }
52 
53 // NO_RETURN does not work with extern "C" for target builds.
Java_Main_destroyJavaVMAndExit(JNIEnv * env,jclass)54 extern "C" JNIEXPORT void JNICALL Java_Main_destroyJavaVMAndExit(JNIEnv* env, jclass) {
55   // Wait for all threads to enter JNI together.
56   JniThreadBarrierWait();
57   // Fake up the managed stack so we can detach.
58   Thread* const self = Thread::Current();
59   self->SetTopOfStack(nullptr);
60   self->SetTopOfShadowStack(nullptr);
61   JavaVM* vm = down_cast<JNIEnvExt*>(env)->GetVm();
62   vm->DetachCurrentThread();
63   // Open ourself again to make sure the native library does not get unloaded from
64   // underneath us due to DestroyJavaVM. b/28406866
65   void* handle = dlopen(kIsDebugBuild ? "libarttestd.so" : "libarttest.so", RTLD_NOW);
66   CHECK(handle != nullptr);
67   vm->DestroyJavaVM();
68   vm_was_shutdown.store(true);
69   // Give threads some time to get stuck in ExceptionCheck.
70   usleep(1000000);
71   if (env != nullptr) {
72     // Use env != nullptr to trick noreturn.
73     exit(0);
74   }
75 }
76 
77 }  // namespace
78 }  // namespace art
79