1 /*
2  * Copyright 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 #ifndef ANDROID_AAUDIO_SHARED_MEMORY_PARCELABLE_H
18 #define ANDROID_AAUDIO_SHARED_MEMORY_PARCELABLE_H
19 
20 #include <stdint.h>
21 #include <sys/mman.h>
22 
23 #include <android-base/unique_fd.h>
24 #include <binder/Parcel.h>
25 #include <binder/Parcelable.h>
26 
27 namespace aaudio {
28 
29 // Arbitrary limits for sanity checks. TODO remove after debugging.
30 #define MAX_SHARED_MEMORIES (32)
31 #define MAX_MMAP_OFFSET_BYTES (32 * 1024 * 8)
32 #define MAX_MMAP_SIZE_BYTES (32 * 1024 * 8)
33 
34 /**
35  * This is a parcelable description of a shared memory referenced by a file descriptor.
36  * It may be divided into several regions.
37  * The memory can be shared using Binder or simply shared between threads.
38  */
39 class SharedMemoryParcelable : public android::Parcelable {
40 public:
41     SharedMemoryParcelable();
42     virtual ~SharedMemoryParcelable();
43 
44     /**
45      * Make a dup() of the fd and store it for later use.
46      *
47      * @param fd
48      * @param sizeInBytes
49      */
50     void setup(const android::base::unique_fd& fd, int32_t sizeInBytes);
51 
52     virtual android::status_t writeToParcel(android::Parcel* parcel) const override;
53 
54     virtual android::status_t readFromParcel(const android::Parcel* parcel) override;
55 
56     // mmap() shared memory
57     aaudio_result_t resolve(int32_t offsetInBytes, int32_t sizeInBytes, void **regionAddressPtr);
58 
59     // munmap() any mapped memory
60     aaudio_result_t close();
61 
62     int32_t getSizeInBytes();
63 
64     void dump();
65 
66 protected:
67 
68 #define MMAP_UNRESOLVED_ADDRESS    reinterpret_cast<uint8_t*>(MAP_FAILED)
69 
70     aaudio_result_t resolveSharedMemory(const android::base::unique_fd& fd);
71 
72     android::base::unique_fd   mFd;
73     int32_t                    mSizeInBytes = 0;
74     uint8_t                   *mResolvedAddress = MMAP_UNRESOLVED_ADDRESS;
75 
76 private:
77 
78     aaudio_result_t validate() const;
79 
80 };
81 
82 } /* namespace aaudio */
83 
84 #endif //ANDROID_AAUDIO_SHARED_MEMORY_PARCELABLE_H
85