1 files changed, 40 insertions, 0 deletions
diff --git a/windows/nsis-plugins/src/os/update.cpp b/windows/nsis-plugins/src/os/update.cpp
new file mode 100644
index 0000000000..2f349ac687
--- /dev/null
+++ b/windows/nsis-plugins/src/os/update.cpp
@@ -0,0 +1,40 @@
+#include <stdafx.h>
+#include "update.h"
+#include <libcommon/error.h>
+#include <libcommon/filesystem.h>
+#include <algorithm>
+#include <fstream>
+#include <filesystem>
+
+namespace
+{
+
+// Jason found this to be a reliable marker of the signature check fix:
+// https://git.zx2c4.com/wireguard-windows/tree/installer/customactions.c#n145
+const char PATCH_MARKER[] = "Signature Hash";
+
+}
+
+namespace update
+{
+
+bool HasSetupApiSha2Fix()
+{
+	common::fs::ScopedNativeFileSystem nativeFileSystem;
+
+	const auto systemDir = common::fs::GetKnownFolderPath(FOLDERID_System, KF_FLAG_DEFAULT, NULL);
+	const auto setupApiPath = std::filesystem::path(systemDir).append(L"setupapi.dll");
+
+	std::ifstream ifs(setupApiPath, std::ios_base::binary);
+	if (!ifs)
+	{
+		// Maybe sketchy to rely on GLE here
+		THROW_WINDOWS_ERROR(GetLastError(), "Failed to open setupapi.dll");
+	}
+
+	const auto marker_end = PATCH_MARKER + sizeof(PATCH_MARKER) - sizeof('\0');
+	const auto last = std::istreambuf_iterator<char>();
+	return (last != std::search(std::istreambuf_iterator<char>(ifs), last, PATCH_MARKER, marker_end));
+}
+
+}