upload android base code part6

android/libnativehelper/include/nativehelper/JniInvocation.h

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+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef JNI_INVOCATION_H_included
+#define JNI_INVOCATION_H_included
+
+#include <jni.h>
+
+// JniInvocation adds a layer of indirection for applications using
+// the JNI invocation API to allow the JNI implementation to be
+// selected dynamically. Apps can specify a specific implementation to
+// be used by calling InitJniInvocation. If this is not done, the
+// library will chosen based on the value of Android system property
+// persist.sys.dalvik.vm.lib on the device, and otherwise fall back to
+// a hard-coded default implementation.
+class JniInvocation {
+ public:
+  JniInvocation();
+
+  ~JniInvocation();
+
+  // Initialize JNI invocation API. library should specifiy a valid
+  // shared library for opening via dlopen providing a JNI invocation
+  // implementation, or null to allow defaulting via
+  // persist.sys.dalvik.vm.lib.
+  bool Init(const char* library);
+
+  // Exposes which library is actually loaded from the given name. The
+  // buffer of size PROPERTY_VALUE_MAX will be used to load the system
+  // property for the default library, if necessary. If no buffer is
+  // provided, the fallback value will be used.
+  static const char* GetLibrary(const char* library, char* buffer);
+
+ private:
+
+  bool FindSymbol(void** pointer, const char* symbol);
+
+  static JniInvocation& GetJniInvocation();
+
+  jint JNI_GetDefaultJavaVMInitArgs(void* vmargs);
+  jint JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args);
+  jint JNI_GetCreatedJavaVMs(JavaVM** vms, jsize size, jsize* vm_count);
+
+  static JniInvocation* jni_invocation_;
+
+  void* handle_;
+  jint (*JNI_GetDefaultJavaVMInitArgs_)(void*);
+  jint (*JNI_CreateJavaVM_)(JavaVM**, JNIEnv**, void*);
+  jint (*JNI_GetCreatedJavaVMs_)(JavaVM**, jsize, jsize*);
+
+  friend jint JNI_GetDefaultJavaVMInitArgs(void* vm_args);
+  friend jint JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args);
+  friend jint JNI_GetCreatedJavaVMs(JavaVM** vms, jsize size, jsize* vm_count);
+};
+
+#endif  // JNI_INVOCATION_H_included