1 /* 2 * Copyright (C) 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 specic language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ANDROID_LIBAPPFUSE_FUSEBUFFER_H_ 18 #define ANDROID_LIBAPPFUSE_FUSEBUFFER_H_ 19 20 #include <android-base/unique_fd.h> 21 #include <linux/fuse.h> 22 23 namespace android { 24 namespace fuse { 25 26 // The numbers came from sdcard.c. 27 // Maximum number of bytes to write/read in one request/one reply. 28 constexpr size_t kFuseMaxWrite = 128 * 1024; 29 constexpr size_t kFuseMaxRead = 128 * 1024; 30 constexpr int32_t kFuseSuccess = 0; 31 32 // Setup sockets to transfer FuseMessage. 33 bool SetupMessageSockets(base::unique_fd (*sockets)[2]); 34 35 enum class ResultOrAgain { 36 kSuccess, 37 kFailure, 38 kAgain, 39 }; 40 41 template<typename T> 42 class FuseMessage { 43 public: 44 bool Read(int fd); 45 bool Write(int fd) const; 46 bool WriteWithBody(int fd, size_t max_size, const void* data) const; 47 ResultOrAgain ReadOrAgain(int fd); 48 ResultOrAgain WriteOrAgain(int fd) const; 49 }; 50 51 // FuseRequest represents file operation requests from /dev/fuse. It starts 52 // from fuse_in_header. The body layout depends on the operation code. 53 struct FuseRequest : public FuseMessage<FuseRequest> { 54 fuse_in_header header; 55 union { 56 // for FUSE_WRITE 57 struct { 58 fuse_write_in write_in; 59 char write_data[kFuseMaxWrite]; 60 }; 61 // for FUSE_OPEN 62 fuse_open_in open_in; 63 // for FUSE_INIT 64 fuse_init_in init_in; 65 // for FUSE_READ 66 fuse_read_in read_in; 67 // for FUSE_LOOKUP 68 char lookup_name[kFuseMaxWrite]; 69 }; 70 void Reset(uint32_t data_length, uint32_t opcode, uint64_t unique); 71 }; 72 73 // FuseResponse represents file operation responses to /dev/fuse. It starts 74 // from fuse_out_header. The body layout depends on the operation code. 75 template <size_t N> 76 struct FuseResponseBase : public FuseMessage<FuseResponseBase<N>> { 77 fuse_out_header header; 78 union { 79 // for FUSE_INIT 80 fuse_init_out init_out; 81 // for FUSE_LOOKUP 82 fuse_entry_out entry_out; 83 // for FUSE_GETATTR 84 fuse_attr_out attr_out; 85 // for FUSE_OPEN 86 fuse_open_out open_out; 87 // for FUSE_READ 88 char read_data[N]; 89 // for FUSE_WRITE 90 fuse_write_out write_out; 91 }; 92 void Reset(uint32_t data_length, int32_t error, uint64_t unique); 93 void ResetHeader(uint32_t data_length, int32_t error, uint64_t unique); 94 }; 95 96 using FuseResponse = FuseResponseBase<kFuseMaxRead>; 97 using FuseSimpleResponse = FuseResponseBase<0u>; 98 99 // To reduce memory usage, FuseBuffer shares the memory region for request and 100 // response. 101 union FuseBuffer final { 102 FuseRequest request; 103 FuseResponse response; 104 105 void HandleInit(); 106 void HandleNotImpl(); 107 }; 108 109 } // namespace fuse 110 } // namespace android 111 112 #endif // ANDROID_LIBAPPFUSE_FUSEBUFFER_H_ 113