1 // 2 // Copyright (C) 2009 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 UPDATE_ENGINE_PAYLOAD_CONSUMER_FILE_WRITER_H_ 18 #define UPDATE_ENGINE_PAYLOAD_CONSUMER_FILE_WRITER_H_ 19 20 #include <fcntl.h> 21 #include <sys/stat.h> 22 #include <sys/types.h> 23 #include <unistd.h> 24 25 #include <base/logging.h> 26 27 #include "update_engine/common/error_code.h" 28 #include "update_engine/common/utils.h" 29 30 // FileWriter is a class that is used to (synchronously, for now) write to 31 // a file. This file is a thin wrapper around open/write/close system calls, 32 // but provides and interface that can be customized by subclasses that wish 33 // to filter the data. 34 35 namespace chromeos_update_engine { 36 37 class FileWriter { 38 public: FileWriter()39 FileWriter() {} ~FileWriter()40 virtual ~FileWriter() {} 41 42 // Wrapper around write. Returns true if all requested bytes 43 // were written, or false on any error, regardless of progress. 44 virtual bool Write(const void* bytes, size_t count) = 0; 45 46 // Same as the Write method above but returns a detailed |error| code 47 // in addition if the returned value is false. By default this method 48 // returns kActionExitDownloadWriteError as the error code, but subclasses 49 // can override if they wish to return more specific error codes. Write(const void * bytes,size_t count,ErrorCode * error)50 virtual bool Write(const void* bytes, 51 size_t count, 52 ErrorCode* error) { 53 *error = ErrorCode::kDownloadWriteError; 54 return Write(bytes, count); 55 } 56 57 // Wrapper around close. Returns 0 on success or -errno on error. 58 virtual int Close() = 0; 59 60 private: 61 DISALLOW_COPY_AND_ASSIGN(FileWriter); 62 }; 63 64 // Direct file writer is probably the simplest FileWriter implementation. 65 // It calls the system calls directly. 66 67 class DirectFileWriter : public FileWriter { 68 public: 69 DirectFileWriter() = default; 70 71 // FileWriter overrides. 72 bool Write(const void* bytes, size_t count) override; 73 int Close() override; 74 75 // Wrapper around open. Returns 0 on success or -errno on error. 76 int Open(const char* path, int flags, mode_t mode); 77 fd()78 int fd() const { return fd_; } 79 80 private: 81 int fd_{-1}; 82 83 DISALLOW_COPY_AND_ASSIGN(DirectFileWriter); 84 }; 85 86 class ScopedFileWriterCloser { 87 public: ScopedFileWriterCloser(FileWriter * writer)88 explicit ScopedFileWriterCloser(FileWriter* writer) : writer_(writer) {} ~ScopedFileWriterCloser()89 ~ScopedFileWriterCloser() { 90 int err = writer_->Close(); 91 if (err) 92 LOG(ERROR) << "FileWriter::Close failed: " 93 << utils::ErrnoNumberAsString(-err); 94 } 95 private: 96 FileWriter* writer_; 97 98 DISALLOW_COPY_AND_ASSIGN(ScopedFileWriterCloser); 99 }; 100 101 } // namespace chromeos_update_engine 102 103 #endif // UPDATE_ENGINE_PAYLOAD_CONSUMER_FILE_WRITER_H_ 104