1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
// 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 || solaris
// +build linux solaris
package fs
import (
"io"
"syscall"
)
func init() {
registerCopyRangeImplementation(CopyRangeMethodSendFile, copyRangeImplementationForBasicFile(copyRangeSendFile))
}
func copyRangeSendFile(src, dst basicFile, srcOffset, dstOffset, size int64) error {
// Check that the destination file has sufficient space
if fi, err := dst.Stat(); err != nil {
return err
} else if fi.Size() < dstOffset+size {
if err := dst.Truncate(dstOffset + size); err != nil {
return err
}
}
// Record old dst offset.
oldDstOffset, err := dst.Seek(0, io.SeekCurrent)
if err != nil {
return err
}
defer func() { _, _ = dst.Seek(oldDstOffset, io.SeekStart) }()
// Seek to the offset we expect to write
if oldDstOffset != dstOffset {
if n, err := dst.Seek(dstOffset, io.SeekStart); err != nil {
return err
} else if n != dstOffset {
return io.ErrUnexpectedEOF
}
}
for size > 0 {
// From the MAN page:
//
// If offset is not NULL, then it points to a variable holding the file offset from which sendfile() will start
// reading data from in_fd. When sendfile() returns, this variable will be set to the offset of the byte
// following the last byte that was read. If offset is not NULL, then sendfile() does not modify the current
// file offset of in_fd; otherwise the current file offset is adjusted to reflect the number of bytes read from
// in_fd.
n, err := withFileDescriptors(dst, src, func(dstFd, srcFd uintptr) (int, error) {
return syscall.Sendfile(int(dstFd), int(srcFd), &srcOffset, int(size))
})
if n == 0 && err == nil {
err = io.ErrUnexpectedEOF
}
if err != nil && err != syscall.EAGAIN {
return err
}
// Handle case where err == EAGAIN and n == -1 (it's not clear if that can happen)
if n > 0 {
size -= int64(n)
}
}
_, err = dst.Seek(oldDstOffset, io.SeekStart)
return err
}
|
