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tailscale/net/dns/registry_windows.go

77 lines
2.1 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// The code in this file originates from https://git.zx2c4.com/wireguard-go:
// Copyright (C) 2017-2020 WireGuard LLC. All Rights Reserved.
// Copying license: https://git.zx2c4.com/wireguard-go/tree/COPYING
package dns
import (
"fmt"
"runtime"
"strings"
"time"
"golang.org/x/sys/windows"
"golang.org/x/sys/windows/registry"
)
func openKeyWait(k registry.Key, path string, access uint32, timeout time.Duration) (registry.Key, error) {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
deadline := time.Now().Add(timeout)
pathSpl := strings.Split(path, "\\")
for i := 0; ; i++ {
keyName := pathSpl[i]
isLast := i+1 == len(pathSpl)
event, err := windows.CreateEvent(nil, 0, 0, nil)
if err != nil {
return 0, fmt.Errorf("windows.CreateEvent: %v", err)
}
defer windows.CloseHandle(event)
var key registry.Key
for {
err = windows.RegNotifyChangeKeyValue(windows.Handle(k), false, windows.REG_NOTIFY_CHANGE_NAME, event, true)
if err != nil {
return 0, fmt.Errorf("windows.RegNotifyChangeKeyValue: %v", err)
}
var accessFlags uint32
if isLast {
accessFlags = access
} else {
accessFlags = registry.NOTIFY
}
key, err = registry.OpenKey(k, keyName, accessFlags)
if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
timeout := time.Until(deadline) / time.Millisecond
if timeout < 0 {
timeout = 0
}
s, err := windows.WaitForSingleObject(event, uint32(timeout))
if err != nil {
return 0, fmt.Errorf("windows.WaitForSingleObject: %v", err)
}
if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
return 0, fmt.Errorf("timeout waiting for registry key")
}
} else if err != nil {
return 0, fmt.Errorf("registry.OpenKey(%v): %v", path, err)
} else {
if isLast {
return key, nil
}
defer key.Close()
break
}
}
k = key
}
}