| /* |
| * Copyright 2018 Google, Inc |
| * |
| * 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 specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef _LIBDM_LOOP_CONTROL_H_ |
| #define _LIBDM_LOOP_CONTROL_H_ |
| |
| #include <string> |
| |
| #include <android-base/unique_fd.h> |
| |
| namespace android { |
| namespace dm { |
| |
| class LoopControl final { |
| public: |
| LoopControl(); |
| |
| // Attaches the file specified by 'file_fd' to the loop device specified |
| // by 'loopdev' |
| bool Attach(int file_fd, std::string* loopdev) const; |
| |
| // Detach the loop device given by 'loopdev' from the attached backing file. |
| bool Detach(const std::string& loopdev) const; |
| |
| LoopControl(const LoopControl&) = delete; |
| LoopControl& operator=(const LoopControl&) = delete; |
| LoopControl& operator=(LoopControl&&) = default; |
| LoopControl(LoopControl&&) = default; |
| |
| private: |
| bool FindFreeLoopDevice(std::string* loopdev) const; |
| |
| static constexpr const char* kLoopControlDevice = "/dev/loop-control"; |
| |
| android::base::unique_fd control_fd_; |
| }; |
| |
| // Create a temporary loop device around a file descriptor or path. |
| class LoopDevice { |
| public: |
| // Create a loop device for the given file descriptor. It is closed when |
| // LoopDevice is destroyed only if auto_close is true. |
| LoopDevice(int fd, bool auto_close = false); |
| // Create a loop device for the given file path. It will be opened for |
| // reading and writing and closed when the loop device is detached. |
| explicit LoopDevice(const std::string& path); |
| ~LoopDevice(); |
| |
| bool valid() const { return fd_ != -1 && !device_.empty(); } |
| const std::string& device() const { return device_; } |
| |
| LoopDevice(const LoopDevice&) = delete; |
| LoopDevice& operator=(const LoopDevice&) = delete; |
| LoopDevice& operator=(LoopDevice&&) = default; |
| LoopDevice(LoopDevice&&) = default; |
| |
| private: |
| void Init(); |
| |
| android::base::unique_fd fd_; |
| bool owns_fd_; |
| std::string device_; |
| LoopControl control_; |
| }; |
| |
| } // namespace dm |
| } // namespace android |
| |
| #endif /* _LIBDM_LOOP_CONTROL_H_ */ |