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
73
74
75
76
|
// Copyright 2015 Tim Heckman. All rights reserved.
// Use of this source code is governed by the BSD 3-Clause
// license that can be found in the LICENSE file.
// +build windows
package flock
import (
"syscall"
"unsafe"
)
var (
kernel32, _ = syscall.LoadLibrary("kernel32.dll")
procLockFileEx, _ = syscall.GetProcAddress(kernel32, "LockFileEx")
procUnlockFileEx, _ = syscall.GetProcAddress(kernel32, "UnlockFileEx")
)
const (
winLockfileFailImmediately = 0x00000001
winLockfileExclusiveLock = 0x00000002
winLockfileSharedLock = 0x00000000
)
// Use of 0x00000000 for the shared lock is a guess based on some the MS Windows
// `LockFileEX` docs, which document the `LOCKFILE_EXCLUSIVE_LOCK` flag as:
//
// > The function requests an exclusive lock. Otherwise, it requests a shared
// > lock.
//
// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
func lockFileEx(handle syscall.Handle, flags uint32, reserved uint32, numberOfBytesToLockLow uint32, numberOfBytesToLockHigh uint32, offset *syscall.Overlapped) (bool, syscall.Errno) {
r1, _, errNo := syscall.Syscall6(
uintptr(procLockFileEx),
6,
uintptr(handle),
uintptr(flags),
uintptr(reserved),
uintptr(numberOfBytesToLockLow),
uintptr(numberOfBytesToLockHigh),
uintptr(unsafe.Pointer(offset)))
if r1 != 1 {
if errNo == 0 {
return false, syscall.EINVAL
}
return false, errNo
}
return true, 0
}
func unlockFileEx(handle syscall.Handle, reserved uint32, numberOfBytesToLockLow uint32, numberOfBytesToLockHigh uint32, offset *syscall.Overlapped) (bool, syscall.Errno) {
r1, _, errNo := syscall.Syscall6(
uintptr(procUnlockFileEx),
5,
uintptr(handle),
uintptr(reserved),
uintptr(numberOfBytesToLockLow),
uintptr(numberOfBytesToLockHigh),
uintptr(unsafe.Pointer(offset)),
0)
if r1 != 1 {
if errNo == 0 {
return false, syscall.EINVAL
}
return false, errNo
}
return true, 0
}
|
