setupapi: Fix struct size mismatches

Signed-off-by: Simon Rozman <simon@rozman.si>

tun/wintun/setupapi/setupapi_windows.go

@@ -34,7 +34,7 @@ func SetupDiCreateDeviceInfoListEx(classGUID *windows.GUID, hwndParent uintptr,
 // SetupDiGetDeviceInfoListDetail function retrieves information associated with a device information set including the class GUID, remote computer handle, and remote computer name.
 func SetupDiGetDeviceInfoListDetail(deviceInfoSet DevInfo) (deviceInfoSetDetailData *DevInfoListDetailData, err error) {
 	data := &DevInfoListDetailData{}
-	data.size = uint32(unsafe.Sizeof(*data))
+	data.size = sizeofDevInfoListDetailData
 
 	return data, setupDiGetDeviceInfoListDetail(deviceInfoSet, data)
 }
@@ -155,10 +155,7 @@ func SetupDiGetDriverInfoDetail(deviceInfoSet DevInfo, deviceInfoData *DevInfoDa
 	var bufLen uint32
 
 	data := (*DrvInfoDetailData)(unsafe.Pointer(&buf[0]))
-
-	// unsafe.Sizeof(data) >= sizeof(SP_DRVINFO_DETAIL_DATA) due to Go trailing padding. SetupAPI expects exactly sizeof(SP_DRVINFO_DETAIL_DATA).
-	sizeAPI := ((unsafe.Sizeof(uintptr(0)) - 1) | (unsafe.Offsetof(data.hardwareID) + unsafe.Sizeof(data.hardwareID) - 1) + 1)
-	data.size = uint32(sizeAPI)
+	data.size = sizeofDrvInfoDetailData
 
 	err := setupDiGetDriverInfoDetail(deviceInfoSet, deviceInfoData, driverInfoData, data, bufCapacity, &bufLen)
 	if err == nil {
@@ -171,7 +168,7 @@ func SetupDiGetDriverInfoDetail(deviceInfoSet DevInfo, deviceInfoData *DevInfoDa
 		// The buffer was too small. Now that we got the required size, create another one big enough and retry.
 		buf := make([]byte, bufLen)
 		data := (*DrvInfoDetailData)(unsafe.Pointer(&buf[0]))
-		data.size = uint32(sizeAPI)
+		data.size = sizeofDrvInfoDetailData
 
 		err = setupDiGetDriverInfoDetail(deviceInfoSet, deviceInfoData, driverInfoData, data, bufLen, &bufLen)
 		if err == nil {

tun/wintun/setupapi/types_windows.go

@@ -60,7 +60,7 @@ type DevInfoData struct {
 
 // DevInfoListDetailData is a structure for detailed information on a device information set (used for SetupDiGetDeviceInfoListDetail which supercedes the functionality of SetupDiGetDeviceInfoListClass).
 type DevInfoListDetailData struct {
-	size                uint32
+	size                uint32 // Warning: unsafe.Sizeof(DevInfoListDetailData) > sizeof(SP_DEVINFO_LIST_DETAIL_DATA) when GOARCH == 386 => use sizeofDevInfoListDetailData const.
 	ClassGUID           windows.GUID
 	RemoteMachineHandle windows.Handle
 	remoteMachineName   [SP_MAX_MACHINENAME_LENGTH]uint16
@@ -371,7 +371,7 @@ func (data *DrvInfoData) IsNewer(driverDate windows.Filetime, driverVersion uint
 
 // DrvInfoDetailData is driver information details structure (provides detailed information about a particular driver information structure)
 type DrvInfoDetailData struct {
-	size            uint32 // On input, this must be exactly the sizeof(DrvInfoDetailData). On output, we set this member to the actual size of structure data.
+	size            uint32 // Warning: unsafe.Sizeof(DrvInfoDetailData) > sizeof(SP_DRVINFO_DETAIL_DATA) when GOARCH == 386 => use sizeofDrvInfoDetailData const.
 	InfDate         windows.Filetime
 	compatIDsOffset uint32
 	compatIDsLength uint32

tun/wintun/setupapi/types_windows_386.go

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package setupapi
+
+const (
+	sizeofDevInfoListDetailData uint32 = 550
+	sizeofDrvInfoDetailData     uint32 = 1570
+)

tun/wintun/setupapi/types_windows_amd64.go

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package setupapi
+
+const (
+	sizeofDevInfoListDetailData uint32 = 560
+	sizeofDrvInfoDetailData     uint32 = 1584
+)