syncthing/lib/fs/basicfs_copy_range_ioctl.go

57 lines
1.4 KiB
Go
Raw Normal View History

// 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/.
//go:build linux
// +build linux
package fs
import (
"io"
"golang.org/x/sys/unix"
)
func init() {
registerCopyRangeImplementation(CopyRangeMethodIoctl, copyRangeImplementationForBasicFile(copyRangeIoctl))
}
func copyRangeIoctl(src, dst basicFile, srcOffset, dstOffset, size int64) error {
fi, err := src.Stat()
if err != nil {
return err
}
if srcOffset+size > fi.Size() {
return io.ErrUnexpectedEOF
}
// https://www.man7.org/linux/man-pages/man2/ioctl_ficlonerange.2.html
// If src_length is zero, the ioctl reflinks to the end of the source file.
if srcOffset+size == fi.Size() {
size = 0
}
if srcOffset == 0 && dstOffset == 0 && size == 0 {
// Optimization for whole file copies.
_, err := withFileDescriptors(src, dst, func(srcFd, dstFd uintptr) (int, error) {
return 0, unix.IoctlFileClone(int(dstFd), int(srcFd))
})
return err
}
_, err = withFileDescriptors(src, dst, func(srcFd, dstFd uintptr) (int, error) {
params := unix.FileCloneRange{
Src_fd: int64(srcFd),
Src_offset: uint64(srcOffset),
Src_length: uint64(size),
Dest_offset: uint64(dstOffset),
}
return 0, unix.IoctlFileCloneRange(int(dstFd), &params)
})
return err
}