1 /*
2  * Copyright (C) 2010 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 #ifndef SCOPEDLOCALREF_H_
18 #define SCOPEDLOCALREF_H_
19 
20 #include <conscrypt/macros.h>
21 #include <jni.h>
22 
23 #include <stddef.h>
24 
25 // A smart pointer that deletes a JNI local reference when it goes out of scope.
26 template <typename T>
27 class ScopedLocalRef {
28 public:
ScopedLocalRef(JNIEnv * env,T localRef)29     ScopedLocalRef(JNIEnv* env, T localRef) : mEnv(env), mLocalRef(localRef) {}
30 
~ScopedLocalRef()31     ~ScopedLocalRef() {
32         reset();
33     }
34 
35     void reset(T ptr = nullptr) {
36         if (ptr != mLocalRef) {
37             if (mLocalRef != nullptr) {
38                 mEnv->DeleteLocalRef(mLocalRef);
39             }
40             mLocalRef = ptr;
41         }
42     }
43 
44     CONSCRYPT_WARN_UNUSED
release()45     T release() {
46         T localRef = mLocalRef;
47         mLocalRef = nullptr;
48         return localRef;
49     }
50 
get()51     T get() const {
52         return mLocalRef;
53     }
54 
55 private:
56     JNIEnv* mEnv;
57     T mLocalRef;
58 
59     // Disallow copy and assignment.
60     ScopedLocalRef(const ScopedLocalRef&);
61     void operator=(const ScopedLocalRef&);
62 };
63 
64 #endif  // SCOPEDLOCALREF_H_
65