1 /* 2 * Copyright (C) 2020 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_INSTALLD_UNIQUE_FILE_H 18 #define ANDROID_INSTALLD_UNIQUE_FILE_H 19 20 #include <functional> 21 #include <string> 22 23 namespace android { 24 namespace installd { 25 26 // A file management helper that serves two purposes: 27 // 28 // 1. Closes the file description on destruction, similar unique_fd. 29 // 2. Runs a cleanup function on after close, if not cancelled. 30 // 31 // The class does not assume the relationship between the given fd and file path. 32 // 33 // Example: 34 // 35 // UniqueFile file(open(...), 36 // filepath, 37 // [](const std::string& path) { 38 // unlink(path.c_str()); 39 // }); 40 // if (file.fd() == -1) { 41 // // Error opening... 42 // } 43 // 44 // ... 45 // if (error) { 46 // // At this point, when the UniqueFile is destructed, the cleanup function will run 47 // // (e.g. to delete the file) after the fd is closed. 48 // return -1; 49 // } 50 // 51 // (Success case) 52 // file.DisableCleanup(); 53 // // At this point, when the UniqueFile is destructed, the cleanup function will not run 54 // // (e.g. leaving the file around) after the fd is closed. 55 // 56 class UniqueFile { 57 private: 58 using CleanUpFunction = std::function<void (const std::string&)>; 59 60 public: 61 UniqueFile(); 62 UniqueFile(int value, std::string path); 63 UniqueFile(int value, std::string path, CleanUpFunction cleanup); 64 UniqueFile(UniqueFile&& other); 65 ~UniqueFile(); 66 67 UniqueFile& operator=(UniqueFile&& other); 68 fd()69 int fd() const { 70 return value_; 71 } 72 path()73 const std::string& path() const { 74 return path_; 75 } 76 DisableAutoClose()77 void DisableAutoClose() { 78 auto_close_ = false; 79 } 80 DisableCleanup()81 void DisableCleanup() { 82 do_cleanup_ = false; 83 } 84 85 void reset(); 86 void reset(int new_value, std::string path, CleanUpFunction new_cleanup = nullptr); 87 88 private: 89 void release(); 90 91 int value_; 92 std::string path_; 93 CleanUpFunction cleanup_; 94 bool do_cleanup_; 95 bool auto_close_; 96 }; 97 98 } // namespace installd 99 } // namespace android 100 101 #endif // ANDROID_INSTALLD_UNIQUE_FILE_H 102