113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specic language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
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#define ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
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#include <android-base/unique_fd.h>
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#include <linux/fuse.h>
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namespace android {
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namespace fuse {
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// The numbers came from sdcard.c.
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// Maximum number of bytes to write/read in one request/one reply.
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constexpr size_t kFuseMaxWrite = 128 * 1024;
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constexpr size_t kFuseMaxRead = 128 * 1024;
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constexpr int32_t kFuseSuccess = 0;
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// Setup sockets to transfer FuseMessage.
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bool SetupMessageSockets(base::unique_fd (*sockets)[2]);
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enum class ResultOrAgain {
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kSuccess,
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kFailure,
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kAgain,
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};
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template<typename T>
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class FuseMessage {
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public:
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bool Read(int fd);
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bool Write(int fd) const;
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bool WriteWithBody(int fd, size_t max_size, const void* data) const;
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ResultOrAgain ReadOrAgain(int fd);
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ResultOrAgain WriteOrAgain(int fd) const;
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};
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// FuseRequest represents file operation requests from /dev/fuse. It starts
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// from fuse_in_header. The body layout depends on the operation code.
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struct FuseRequest : public FuseMessage<FuseRequest> {
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fuse_in_header header;
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union {
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// for FUSE_WRITE
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struct {
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fuse_write_in write_in;
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char write_data[kFuseMaxWrite];
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};
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// for FUSE_OPEN
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fuse_open_in open_in;
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// for FUSE_INIT
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fuse_init_in init_in;
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// for FUSE_READ
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fuse_read_in read_in;
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// for FUSE_LOOKUP
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char lookup_name[kFuseMaxWrite];
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};
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void Reset(uint32_t data_length, uint32_t opcode, uint64_t unique);
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};
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// FuseResponse represents file operation responses to /dev/fuse. It starts
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// from fuse_out_header. The body layout depends on the operation code.
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template <size_t N>
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struct FuseResponseBase : public FuseMessage<FuseResponseBase<N>> {
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fuse_out_header header;
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union {
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// for FUSE_INIT
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fuse_init_out init_out;
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// for FUSE_LOOKUP
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fuse_entry_out entry_out;
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// for FUSE_GETATTR
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fuse_attr_out attr_out;
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// for FUSE_OPEN
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fuse_open_out open_out;
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// for FUSE_READ
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char read_data[N];
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// for FUSE_WRITE
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fuse_write_out write_out;
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};
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void Reset(uint32_t data_length, int32_t error, uint64_t unique);
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void ResetHeader(uint32_t data_length, int32_t error, uint64_t unique);
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};
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using FuseResponse = FuseResponseBase<kFuseMaxRead>;
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using FuseSimpleResponse = FuseResponseBase<0u>;
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// To reduce memory usage, FuseBuffer shares the memory region for request and
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// response.
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union FuseBuffer final {
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FuseRequest request;
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FuseResponse response;
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void HandleInit();
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void HandleNotImpl();
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};
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} // namespace fuse
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} // namespace android
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#endif // ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
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