Switch to C based msi hooks for win installer

Fixes automated WSL installation on ARM

Signed-off-by: Jason T. Greene <jason.greene@redhat.com>

cmd/podman-msihooks/main.go

@@ -1,46 +0,0 @@
-//go:build windows
-// +build windows
-
-package main
-
-import (
-	"C"
-	"syscall"
-	"unsafe"
-
-	"github.com/containers/podman/v4/pkg/machine/wsl"
-)
-
-const KernelWarning = "WSL Kernel installation did not complete successfully. " +
-	"Podman machine will attempt to install this at a later time. " +
-	"You can also manually complete the installation using the " +
-	"\"wsl --update\" command."
-
-//export CheckWSL
-func CheckWSL(hInstall uint32) uint32 {
-	installed := wsl.IsWSLInstalled()
-	feature := wsl.IsWSLFeatureEnabled()
-	setMsiProperty(hInstall, "HAS_WSL", strBool(installed))
-	setMsiProperty(hInstall, "HAS_WSLFEATURE", strBool(feature))
-
-	return 0
-}
-
-func setMsiProperty(hInstall uint32, name string, value string) {
-	nameW, _ := syscall.UTF16PtrFromString(name)
-	valueW, _ := syscall.UTF16PtrFromString(value)
-
-	msi := syscall.NewLazyDLL("msi")
-	proc := msi.NewProc("MsiSetPropertyW")
-	_, _, _ = proc.Call(uintptr(hInstall), uintptr(unsafe.Pointer(nameW)), uintptr(unsafe.Pointer(valueW)))
-
-}
-func strBool(val bool) string {
-	if val {
-		return "1"
-	}
-
-	return "0"
-}
-
-func main() {}

contrib/win-installer/build-hooks.bat

@@ -1,4 +1,6 @@
 cd ../..
-go build -buildmode=c-shared  -o contrib/win-installer/artifacts/podman-msihooks.dll ./cmd/podman-msihooks || exit /b 1
+set GOARCH=amd64
 go build -ldflags -H=windowsgui -o contrib/win-installer/artifacts/podman-wslkerninst.exe ./cmd/podman-wslkerninst || exit /b 1
 cd contrib/win-installer
+@rem Build using x86 toolchain, see comments in check.c for rationale and details
+x86_64-w64-mingw32-gcc podman-msihooks/check.c -shared -lmsi -mwindows -o artifacts/podman-msihooks.dll || exit /b 1

contrib/win-installer/podman-msihooks/check.c

@@ -0,0 +1,66 @@
+#include <windows.h>
+#include <MsiQuery.h>
+
+BOOL isWSLEnabled();
+LPCWSTR boolToNStr(BOOL bool);
+
+/**
+ * CheckWSL is a custom action loaded by the Podman Windows installer
+ * to determine whether the system already has WSL installed.
+ *
+ * The intention is that this action is compiled for x86_64, which
+ * can be ran on both Intel and Arm based systems (the latter through
+ * emulation). While the code should build fine on MSVC and clang, the
+ * intended usage is MingW-W64 (cross-compiling gcc targeting Windows).
+ *
+ * Previously this was implemented as a Golang c-shared cgo library,
+ * however, the WoW x86_64 emulation layer struggled with dynamic
+ * hot-loaded transformation of the goruntime into an existing process
+ * (required by MSI custom actions). In the future this could be
+ * converted back, should the emulation issue be resolved.
+ */
+
+ __declspec(dllexport) UINT __cdecl CheckWSL(MSIHANDLE hInstall) {
+	BOOL hasWSL = isWSLEnabled();
+	// Set a property with the WSL state for the installer to operate on
+	MsiSetPropertyW(hInstall, L"HAS_WSLFEATURE", boolToNStr(hasWSL));
+
+	return 0;
+}
+
+LPCWSTR boolToNStr(BOOL bool) {
+	return bool ? L"1" : L"0";
+}
+
+BOOL isWSLEnabled() {
+	/*
+	 * The simplest, and most reliable check across all variants and versions
+	 * of WSL appears to be changing the default version to WSL 2 and check
+	 * for errors, which we need to do anyway.
+	 */
+	STARTUPINFOW startup;
+	PROCESS_INFORMATION process;
+
+	ZeroMemory(&startup, sizeof(STARTUPINFOW));
+	startup.cb = sizeof(STARTUPINFOW);
+
+	// These settings hide the console window, so there is no annoying flash
+	startup.dwFlags = STARTF_USESHOWWINDOW;
+	startup.wShowWindow = SW_HIDE;
+
+	// CreateProcessW requires lpCommandLine to be mutable
+	wchar_t cmd[] = L"wsl --set-default-version 2";
+	if (! CreateProcessW(NULL, cmd, NULL, NULL, FALSE, CREATE_NEW_CONSOLE,
+					     NULL, NULL, &startup, &process)) {
+
+		return FALSE;
+	}
+
+	DWORD exitCode;
+	WaitForSingleObject(process.hProcess, INFINITE);
+	if (! GetExitCodeProcess(process.hProcess, &exitCode)) {
+		return FALSE;
+	}
+
+	return exitCode == 0;
+}