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/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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 ART_RUNTIME_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
#define ART_RUNTIME_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
#include <stdint.h>
namespace unix_file {
// A file interface supporting random-access reading and writing of content,
// along with the ability to set the length of a file (smaller or greater than
// its current extent).
//
// This interface does not support a stream position (i.e. every read or write
// must specify an offset). This interface does not imply any buffering policy.
//
// All operations return >= 0 on success or -errno on failure.
//
// Implementations never return EINTR; callers are spared the need to manually
// retry interrupted operations.
//
// Any concurrent access to files should be externally synchronized.
class RandomAccessFile {
public:
virtual ~RandomAccessFile() { }
virtual int Close() = 0;
// Reads 'byte_count' bytes into 'buf' starting at offset 'offset' in the
// file. Returns the number of bytes actually read.
virtual int64_t Read(char* buf, int64_t byte_count, int64_t offset) const = 0;
// Sets the length of the file to 'new_length'. If this is smaller than the
// file's current extent, data is discarded. If this is greater than the
// file's current extent, it is as if a write of the relevant number of zero
// bytes occurred. Returns 0 on success.
virtual int SetLength(int64_t new_length) = 0;
// Returns the current size of this file.
virtual int64_t GetLength() const = 0;
// Writes 'byte_count' bytes from 'buf' starting at offset 'offset' in the
// file. Zero-byte writes are acceptable, and writes past the end are as if
// a write of the relevant number of zero bytes also occurred. Returns the
// number of bytes actually written.
virtual int64_t Write(const char* buf, int64_t byte_count, int64_t offset) = 0;
// Flushes file data.
virtual int Flush() = 0;
};
} // namespace unix_file
#endif // ART_RUNTIME_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
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