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