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69 lines
2.5 KiB
69 lines
2.5 KiB
/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_LIBARTBASE_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
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#define ART_LIBARTBASE_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
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#include <stdint.h>
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namespace unix_file {
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// A file interface supporting random-access reading and writing of content,
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// along with the ability to set the length of a file (smaller or greater than
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// its current extent).
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//
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// This interface does not support a stream position (i.e. every read or write
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// must specify an offset). This interface does not imply any buffering policy.
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//
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// All operations return >= 0 on success or -errno on failure.
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//
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// Implementations never return EINTR; callers are spared the need to manually
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// retry interrupted operations.
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//
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// Any concurrent access to files should be externally synchronized.
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class RandomAccessFile {
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public:
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virtual ~RandomAccessFile() { }
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virtual int Close() = 0;
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// Reads 'byte_count' bytes into 'buf' starting at offset 'offset' in the
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// file. Returns the number of bytes actually read.
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virtual int64_t Read(char* buf, int64_t byte_count, int64_t offset) const = 0;
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// Sets the length of the file to 'new_length'. If this is smaller than the
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// file's current extent, data is discarded. If this is greater than the
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// file's current extent, it is as if a write of the relevant number of zero
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// bytes occurred. Returns 0 on success.
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virtual int SetLength(int64_t new_length) = 0;
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// Returns the current size of this file.
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virtual int64_t GetLength() const = 0;
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// Writes 'byte_count' bytes from 'buf' starting at offset 'offset' in the
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// file. Zero-byte writes are acceptable, and writes past the end are as if
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// a write of the relevant number of zero bytes also occurred. Returns the
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// number of bytes actually written.
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virtual int64_t Write(const char* buf, int64_t byte_count, int64_t offset) = 0;
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// Flushes file data.
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virtual int Flush() = 0;
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};
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} // namespace unix_file
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#endif // ART_LIBARTBASE_BASE_UNIX_FILE_RANDOM_ACCESS_FILE_H_
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