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 SCOPED_BYTES_H_included
18#define SCOPED_BYTES_H_included
19
20#include "JNIHelp.h"
21
22/**
23 * ScopedBytesRO and ScopedBytesRW attempt to paper over the differences between byte[]s and
24 * ByteBuffers. This in turn helps paper over the differences between non-direct ByteBuffers backed
25 * by byte[]s, direct ByteBuffers backed by bytes[]s, and direct ByteBuffers not backed by byte[]s.
26 * (On Android, this last group only contains MappedByteBuffers.)
27 */
28template<bool readOnly>
29class ScopedBytes {
30public:
31    ScopedBytes(JNIEnv* env, jobject object)
32    : mEnv(env), mObject(object), mByteArray(NULL), mPtr(NULL)
33    {
34        if (mObject == NULL) {
35            jniThrowNullPointerException(mEnv, NULL);
36        } else if (mEnv->IsInstanceOf(mObject, JniConstants::byteArrayClass)) {
37            mByteArray = reinterpret_cast<jbyteArray>(mObject);
38            mPtr = mEnv->GetByteArrayElements(mByteArray, NULL);
39        } else {
40            mPtr = reinterpret_cast<jbyte*>(mEnv->GetDirectBufferAddress(mObject));
41        }
42    }
43
44    ~ScopedBytes() {
45        if (mByteArray != NULL) {
46            mEnv->ReleaseByteArrayElements(mByteArray, mPtr, readOnly ? JNI_ABORT : 0);
47        }
48    }
49
50private:
51    JNIEnv* mEnv;
52    jobject mObject;
53    jbyteArray mByteArray;
54
55protected:
56    jbyte* mPtr;
57
58private:
59    // Disallow copy and assignment.
60    ScopedBytes(const ScopedBytes&);
61    void operator=(const ScopedBytes&);
62};
63
64class ScopedBytesRO : public ScopedBytes<true> {
65public:
66    ScopedBytesRO(JNIEnv* env, jobject object) : ScopedBytes<true>(env, object) {}
67    const jbyte* get() const {
68        return mPtr;
69    }
70};
71
72class ScopedBytesRW : public ScopedBytes<false> {
73public:
74    ScopedBytesRW(JNIEnv* env, jobject object) : ScopedBytes<false>(env, object) {}
75    jbyte* get() {
76        return mPtr;
77    }
78};
79
80#endif  // SCOPED_BYTES_H_included
81