Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 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_LIBARTBASE_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_ |
| 18 | #define ART_LIBARTBASE_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_ |
| 19 | |
| 20 | #include <stdint.h> |
| 21 | |
| 22 | namespace unix_file { |
| 23 | |
| 24 | // A file interface supporting random-access reading and writing of content, |
| 25 | // along with the ability to set the length of a file (smaller or greater than |
| 26 | // its current extent). |
| 27 | // |
| 28 | // This interface does not support a stream position (i.e. every read or write |
| 29 | // must specify an offset). This interface does not imply any buffering policy. |
| 30 | // |
| 31 | // All operations return >= 0 on success or -errno on failure. |
| 32 | // |
| 33 | // Implementations never return EINTR; callers are spared the need to manually |
| 34 | // retry interrupted operations. |
| 35 | // |
| 36 | // Any concurrent access to files should be externally synchronized. |
| 37 | class RandomAccessFile { |
| 38 | public: |
| 39 | virtual ~RandomAccessFile() { } |
| 40 | |
| 41 | virtual int Close() = 0; |
| 42 | |
| 43 | // Reads 'byte_count' bytes into 'buf' starting at offset 'offset' in the |
| 44 | // file. Returns the number of bytes actually read. |
| 45 | virtual int64_t Read(char* buf, int64_t byte_count, int64_t offset) const = 0; |
| 46 | |
| 47 | // Sets the length of the file to 'new_length'. If this is smaller than the |
| 48 | // file's current extent, data is discarded. If this is greater than the |
| 49 | // file's current extent, it is as if a write of the relevant number of zero |
| 50 | // bytes occurred. Returns 0 on success. |
| 51 | virtual int SetLength(int64_t new_length) = 0; |
| 52 | |
| 53 | // Returns the current size of this file. |
| 54 | virtual int64_t GetLength() const = 0; |
| 55 | |
| 56 | // Writes 'byte_count' bytes from 'buf' starting at offset 'offset' in the |
| 57 | // file. Zero-byte writes are acceptable, and writes past the end are as if |
| 58 | // a write of the relevant number of zero bytes also occurred. Returns the |
| 59 | // number of bytes actually written. |
| 60 | virtual int64_t Write(const char* buf, int64_t byte_count, int64_t offset) = 0; |
| 61 | |
| 62 | // Flushes file data. |
| 63 | virtual int Flush() = 0; |
| 64 | }; |
| 65 | |
| 66 | } // namespace unix_file |
| 67 | |
| 68 | #endif // ART_LIBARTBASE_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_ |