android: Add CHECK() calls to better understand memory corruption.

base/android/jni_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/android/jni_android.h"
 
 #include <map>
 
 #include "base/android/build_info.h"
 #include "base/android/jni_string.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 
 namespace {
 using base::android::GetClass;
 using base::android::MethodID;
 using base::android::ScopedJavaLocalRef;
 
 JavaVM* g_jvm = NULL;
+const JNIInvokeInterface* g_jvm_functions = NULL;

[joth, 2013/11/25 17:08:42]

Is the layout of JNIInvokeInterface guaranteed to be consistent across platform
versions?

FWIW I'd put the comment here that this variable, and all usage of it, is for
debugging crbug/xxx

[digit1, 2013/11/25 17:34:02]

Yes, since the structure is defined in <jni.h>, its layout must be stable to
avoid breaking generated machine code.

I'll add some comments though.

[digit1, 2013/11/25 17:35:53]

Done.

+
 // Leak the global app context, as it is used from a non-joinable worker thread
 // that may still be running at shutdown. There is no harm in doing this.
 base::LazyInstance<base::android::ScopedJavaGlobalRef<jobject> >::Leaky
     g_application_context = LAZY_INSTANCE_INITIALIZER;
 
 std::string GetJavaExceptionInfo(JNIEnv* env, jthrowable java_throwable) {
   ScopedJavaLocalRef<jclass> throwable_clazz =
       GetClass(env, "java/lang/Throwable");
   jmethodID throwable_printstacktrace =
       MethodID::Get<MethodID::TYPE_INSTANCE>(
@@ skipping 39 matching lines @@
 }
 
 }  // namespace
 
 namespace base {
 namespace android {
 
 JNIEnv* AttachCurrentThread() {
   DCHECK(g_jvm);
   JNIEnv* env = NULL;
-  jint ret = g_jvm->AttachCurrentThread(&env, NULL);
+  // See http://crbug.com/322200 for the reasons for these CHECKs.
+  CHECK(g_jvm);
+  CHECK_EQ(g_jvm_functions, g_jvm->functions);
+  jint ret = g_jvm_functions->AttachCurrentThread(g_jvm, &env, NULL);
   DCHECK_EQ(JNI_OK, ret);
   return env;
 }
 
 void DetachFromVM() {
   // Ignore the return value, if the thread is not attached, DetachCurrentThread
   // will fail. But it is ok as the native thread may never be attached.
-  if (g_jvm)
+  if (g_jvm) {
+    // See http://crbug.com/322200 for the reasons for these CHECKs.
+    CHECK(g_jvm);
+    CHECK_EQ(g_jvm_functions, g_jvm->functions);
     g_jvm->DetachCurrentThread();
+  }
 }
 
 void InitVM(JavaVM* vm) {
   DCHECK(!g_jvm);
   g_jvm = vm;
+  g_jvm_functions = vm->functions;
 }
 
 bool IsVMInitialized() {
   return g_jvm != NULL;
 }
 
 void InitApplicationContext(JNIEnv* env, const JavaRef<jobject>& context) {
   if (env->IsSameObject(g_application_context.Get().obj(), context.obj())) {
     // It's safe to set the context more than once if it's the same context.
     return;
@@ skipping 95 matching lines @@
   // RVO should avoid any extra copies of the exception string.
   base::android::BuildInfo::GetInstance()->set_java_exception_info(
       GetJavaExceptionInfo(env, java_throwable));
 
   // Now, feel good about it and die.
   CHECK(false);
 }
 
 }  // namespace android
 }  // namespace base