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 ART_RUNTIME_BASE_UNIX_FILE_NULL_FILE_H_ 18 #define ART_RUNTIME_BASE_UNIX_FILE_NULL_FILE_H_ 19 20 #include "base/unix_file/random_access_file.h" 21 #include "base/macros.h" 22 23 namespace unix_file { 24 25 // A RandomAccessFile implementation equivalent to /dev/null. Writes are 26 // discarded, and there's no data to be read. Callers could use FdFile in 27 // conjunction with /dev/null, but that's not portable and costs a file 28 // descriptor. NullFile is "free". 29 // 30 // Thread safe. 31 class NullFile : public RandomAccessFile { 32 public: 33 NullFile(); 34 virtual ~NullFile(); 35 36 // RandomAccessFile API. 37 virtual int Close(); 38 virtual int Flush(); 39 virtual int64_t Read(char* buf, int64_t byte_count, int64_t offset) const; 40 virtual int SetLength(int64_t new_length); 41 virtual int64_t GetLength() const; 42 virtual int64_t Write(const char* buf, int64_t byte_count, int64_t offset); 43 44 private: 45 DISALLOW_COPY_AND_ASSIGN(NullFile); 46 }; 47 48 } // namespace unix_file 49 50 #endif // ART_RUNTIME_BASE_UNIX_FILE_NULL_FILE_H_ 51