mirror of
https://github.com/octoleo/syncthing.git
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46 lines
1.0 KiB
Go
46 lines
1.0 KiB
Go
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// Copyright (C) 2019 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package fs
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import (
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"io"
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)
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func init() {
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registerCopyRangeImplementation(CopyRangeMethodStandard, copyRangeStandard)
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}
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func copyRangeStandard(src, dst File, srcOffset, dstOffset, size int64) error {
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const bufSize = 4 << 20
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buf := make([]byte, bufSize)
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// TODO: In go 1.15, we should use file.ReadFrom that uses copy_file_range underneath.
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// ReadAt and WriteAt does not modify the position of the file.
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for size > 0 {
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if size < bufSize {
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buf = buf[:size]
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}
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n, err := src.ReadAt(buf, srcOffset)
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if err != nil {
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if err == io.EOF {
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return io.ErrUnexpectedEOF
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}
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return err
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}
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if _, err = dst.WriteAt(buf[:n], dstOffset); err != nil {
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return err
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}
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srcOffset += int64(n)
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dstOffset += int64(n)
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size -= int64(n)
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}
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return nil
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}
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