94 lines
2.1 KiB
Go
94 lines
2.1 KiB
Go
// 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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// +build linux
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package fs
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import (
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"io"
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"syscall"
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"unsafe"
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)
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func init() {
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registerCopyRangeImplementation(CopyRangeMethodIoctl, copyRangeImplementationForBasicFile(copyRangeIoctl))
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}
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const FICLONE = 0x40049409
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const FICLONERANGE = 0x4020940d
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/*
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http://man7.org/linux/man-pages/man2/ioctl_ficlonerange.2.html
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struct file_clone_range {
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__s64 src_fd;
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__u64 src_offset;
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__u64 src_length;
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__u64 dest_offset;
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};
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*/
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type fileCloneRange struct {
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srcFd int64
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srcOffset uint64
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srcLength uint64
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dstOffset uint64
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}
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func copyRangeIoctl(src, dst basicFile, srcOffset, dstOffset, size int64) error {
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fi, err := src.Stat()
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if err != nil {
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return err
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}
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if srcOffset+size > fi.Size() {
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return io.ErrUnexpectedEOF
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}
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// https://www.man7.org/linux/man-pages/man2/ioctl_ficlonerange.2.html
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// If src_length is zero, the ioctl reflinks to the end of the source file.
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if srcOffset+size == fi.Size() {
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size = 0
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}
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if srcOffset == 0 && dstOffset == 0 && size == 0 {
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// Optimization for whole file copies.
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var errNo syscall.Errno
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_, err := withFileDescriptors(src, dst, func(srcFd, dstFd uintptr) (int, error) {
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_, _, errNo = syscall.Syscall(syscall.SYS_IOCTL, dstFd, FICLONE, srcFd)
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return 0, nil
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})
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// Failure in withFileDescriptors
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if err != nil {
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return err
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}
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if errNo != 0 {
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return errNo
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}
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return nil
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}
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var errNo syscall.Errno
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_, err = withFileDescriptors(src, dst, func(srcFd, dstFd uintptr) (int, error) {
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params := fileCloneRange{
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srcFd: int64(srcFd),
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srcOffset: uint64(srcOffset),
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srcLength: uint64(size),
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dstOffset: uint64(dstOffset),
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}
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_, _, errNo = syscall.Syscall(syscall.SYS_IOCTL, dstFd, FICLONERANGE, uintptr(unsafe.Pointer(¶ms)))
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return 0, nil
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})
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// Failure in withFileDescriptors
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if err != nil {
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return err
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}
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if errNo != 0 {
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return errNo
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}
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return nil
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}
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