From d8a6a50129bd0ce6ab93c1a73f4be0ebd9b30b25 Mon Sep 17 00:00:00 2001
From: Lomanic <lomanic@hotmail.fr>
Date: Mon, 18 Jun 2018 22:17:31 +0200
Subject: [PATCH] Revert "[host][windows] Refactor code to query registry via
 golang.org/x/sys/windows/registry"

This reverts commit c729bbd6a8e6fd243e2f43c24666c29feb3e6294.
---
 host/host_windows.go | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/host/host_windows.go b/host/host_windows.go
index 1c65c5c..6fe6142 100644
--- a/host/host_windows.go
+++ b/host/host_windows.go
@@ -15,6 +15,7 @@ import (
 
 	"github.com/shirou/gopsutil/internal/common"
 	process "github.com/shirou/gopsutil/process"
+	"golang.org/x/sys/windows"
 	"golang.org/x/sys/windows/registry"
 )
 
@@ -93,15 +94,30 @@ func InfoWithContext(ctx context.Context) (*InfoStat, error) {
 }
 
 func getMachineGuid() (string, error) {
-	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Cryptography`, registry.QUERY_VALUE)
+	var h windows.Handle
+	err := windows.RegOpenKeyEx(windows.HKEY_LOCAL_MACHINE, windows.StringToUTF16Ptr(`SOFTWARE\Microsoft\Cryptography`), 0, windows.KEY_READ|windows.KEY_WOW64_64KEY, &h)
 	if err != nil {
 		return "", err
 	}
-	defer k.Close()
-	hostID, _, err := k.GetStringValue("MachineGuid")
+	defer windows.RegCloseKey(h)
+
+	const windowsRegBufLen = 74 // len(`{`) + len(`abcdefgh-1234-456789012-123345456671` * 2) + len(`}`) // 2 == bytes/UTF16
+	const uuidLen = 36
+
+	var regBuf [windowsRegBufLen]uint16
+	bufLen := uint32(windowsRegBufLen)
+	var valType uint32
+	err = windows.RegQueryValueEx(h, windows.StringToUTF16Ptr(`MachineGuid`), nil, &valType, (*byte)(unsafe.Pointer(&regBuf[0])), &bufLen)
 	if err != nil {
 		return "", err
 	}
+
+	hostID := windows.UTF16ToString(regBuf[:])
+	hostIDLen := len(hostID)
+	if hostIDLen != uuidLen {
+		return "", fmt.Errorf("HostID incorrect: %q\n", hostID)
+	}
+
 	return hostID, nil
 }