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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specic language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
#define ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
#include <android-base/unique_fd.h>
#include <linux/fuse.h>
namespace android {
namespace fuse {
// The numbers came from sdcard.c.
// Maximum number of bytes to write/read in one request/one reply.
constexpr size_t kFuseMaxWrite = 256 * 1024;
constexpr size_t kFuseMaxRead = 128 * 1024;
constexpr int32_t kFuseSuccess = 0;
// Setup sockets to transfer FuseMessage.
bool SetupMessageSockets(base::unique_fd (*sockets)[2]);
enum class ResultOrAgain {
kSuccess,
kFailure,
kAgain,
};
template<typename T>
class FuseMessage {
public:
bool Read(int fd);
bool Write(int fd) const;
ResultOrAgain ReadOrAgain(int fd);
ResultOrAgain WriteOrAgain(int fd) const;
private:
bool CheckHeaderLength(const char* name) const;
};
// FuseRequest represents file operation requests from /dev/fuse. It starts
// from fuse_in_header. The body layout depends on the operation code.
struct FuseRequest : public FuseMessage<FuseRequest> {
fuse_in_header header;
union {
// for FUSE_WRITE
struct {
fuse_write_in write_in;
char write_data[kFuseMaxWrite];
};
// for FUSE_OPEN
fuse_open_in open_in;
// for FUSE_INIT
fuse_init_in init_in;
// for FUSE_READ
fuse_read_in read_in;
// for FUSE_LOOKUP
char lookup_name[kFuseMaxWrite];
};
void Reset(uint32_t data_length, uint32_t opcode, uint64_t unique);
};
// FuseResponse represents file operation responses to /dev/fuse. It starts
// from fuse_out_header. The body layout depends on the operation code.
struct FuseResponse : public FuseMessage<FuseResponse> {
fuse_out_header header;
union {
// for FUSE_INIT
fuse_init_out init_out;
// for FUSE_LOOKUP
fuse_entry_out entry_out;
// for FUSE_GETATTR
fuse_attr_out attr_out;
// for FUSE_OPEN
fuse_open_out open_out;
// for FUSE_READ
char read_data[kFuseMaxRead];
// for FUSE_WRITE
fuse_write_out write_out;
};
void Reset(uint32_t data_length, int32_t error, uint64_t unique);
void ResetHeader(uint32_t data_length, int32_t error, uint64_t unique);
};
// To reduce memory usage, FuseBuffer shares the memory region for request and
// response.
union FuseBuffer final {
FuseRequest request;
FuseResponse response;
void HandleInit();
void HandleNotImpl();
};
} // namespace fuse
} // namespace android
#endif // ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
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