From 1ff37e2b0706143c5da7131ae13f45d0d1882344 Mon Sep 17 00:00:00 2001
From: Simon Rozman <simon@rozman.si>
Date: Fri, 2 Aug 2019 15:48:41 +0200
Subject: [PATCH] wintun: merge opening device registry key

This also introduces waiting for key to appear on initial access.

See if this resolves the issue caused by HDD power-up delay resulting in
failure to create the adapter.

Signed-off-by: Simon Rozman <simon@rozman.si>
---
 tun/wintun/wintun_windows.go | 36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

diff --git a/tun/wintun/wintun_windows.go b/tun/wintun/wintun_windows.go
index 7550263..55d4ed0 100644
--- a/tun/wintun/wintun_windows.go
+++ b/tun/wintun/wintun_windows.go
@@ -262,14 +262,23 @@ func CreateInterface(description string, requestedGUID *windows.GUID) (wintun *W
 	devInfoList.CallClassInstaller(setupapi.DIF_REGISTER_COINSTALLERS, deviceData)
 
 	var key registry.Key
-	if requestedGUID != nil {
-		key, err = devInfoList.OpenDevRegKey(deviceData, setupapi.DICS_FLAG_GLOBAL, 0, setupapi.DIREG_DRV, registry.SET_VALUE)
-		if err != nil {
-			err = fmt.Errorf("OpenDevRegKey failed: %v", err)
-			return
+	const pollTimeout = time.Millisecond * 50
+	for i := 0; i < int(waitForRegistryTimeout/pollTimeout); i++ {
+		if i != 0 {
+			time.Sleep(pollTimeout)
 		}
+		key, err = devInfoList.OpenDevRegKey(deviceData, setupapi.DICS_FLAG_GLOBAL, 0, setupapi.DIREG_DRV, registry.SET_VALUE|registry.QUERY_VALUE|registry.NOTIFY)
+		if err == nil {
+			break
+		}
+	}
+	if err != nil {
+		err = fmt.Errorf("SetupDiOpenDevRegKey failed: %v", err)
+		return
+	}
+	defer key.Close()
+	if requestedGUID != nil {
 		err = key.SetStringValue("NetSetupAnticipatedInstanceId", requestedGUID.String())
-		key.Close()
 		if err != nil {
 			err = fmt.Errorf("SetStringValue(NetSetupAnticipatedInstanceId) failed: %v", err)
 			return
@@ -309,21 +318,6 @@ func CreateInterface(description string, requestedGUID *windows.GUID) (wintun *W
 	// DIF_INSTALLDEVICE returns almost immediately, while the device installation
 	// continues in the background. It might take a while, before all registry
 	// keys and values are populated.
-	const pollTimeout = time.Millisecond * 50
-	for i := 0; i < int(waitForRegistryTimeout/pollTimeout); i++ {
-		if i != 0 {
-			time.Sleep(pollTimeout)
-		}
-		key, err = devInfoList.OpenDevRegKey(deviceData, setupapi.DICS_FLAG_GLOBAL, 0, setupapi.DIREG_DRV, registry.QUERY_VALUE|registry.NOTIFY)
-		if err == nil {
-			break
-		}
-	}
-	if err != nil {
-		err = fmt.Errorf("SetupDiOpenDevRegKey failed: %v", err)
-		return
-	}
-	defer key.Close()
 	_, err = registryEx.GetStringValueWait(key, "NetCfgInstanceId", waitForRegistryTimeout)
 	if err != nil {
 		err = fmt.Errorf("GetStringValueWait(NetCfgInstanceId) failed: %v", err)