Use file mapping for patch check

1 files changed, 64 insertions, 7 deletions

diff --git a/windows/nsis-plugins/src/os/update.cpp b/windows/nsis-plugins/src/os/update.cpp
index 2f349ac687..a300882407 100644
--- a/windows/nsis-plugins/src/os/update.cpp
+++ b/windows/nsis-plugins/src/os/update.cpp
@@ -2,6 +2,7 @@
 #include "update.h"
 #include <libcommon/error.h>
 #include <libcommon/filesystem.h>
+#include <libcommon/memory.h>
 #include <algorithm>
 #include <fstream>
 #include <filesystem>
@@ -20,21 +21,77 @@ namespace update
 
 bool HasSetupApiSha2Fix()
 {
+	common::memory::ScopeDestructor destructor;
+
 	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)
+	const auto setupApiHandle = CreateFileW(
+		setupApiPath.c_str(),
+		GENERIC_READ,
+		FILE_SHARE_READ,
+		nullptr,
+		OPEN_EXISTING,
+		FILE_ATTRIBUTE_NORMAL,
+		nullptr
+	);
+
+	if (INVALID_HANDLE_VALUE == setupApiHandle)
+	{
+		THROW_WINDOWS_ERROR(GetLastError(), "CreateFileW");
+	}
+
+	destructor += [=]() {
+		CloseHandle(setupApiHandle);
+	};
+
+	const auto mapping = CreateFileMappingW(setupApiHandle, nullptr, PAGE_READONLY, 0, 0, nullptr);
+
+	if (nullptr == mapping)
+	{
+		THROW_WINDOWS_ERROR(GetLastError(), "CreateFileMappingW");
+	}
+
+	destructor += [=]() {
+		CloseHandle(mapping);
+	};
+
+	const auto bytes = MapViewOfFile(mapping, FILE_MAP_READ, 0, 0, 0);
+
+	if (nullptr == bytes)
+	{
+		THROW_WINDOWS_ERROR(GetLastError(), "MapViewOfFile");
+	}
+
+	destructor += [=]() {
+		UnmapViewOfFile(bytes);
+	};
+
+	MEMORY_BASIC_INFORMATION meminfo;
+
+	if (0 == VirtualQuery(bytes, &meminfo, sizeof(meminfo)))
+	{
+		THROW_WINDOWS_ERROR(GetLastError(), "CreateFileW");
+	}
+
+	constexpr auto PATCH_MARKER_SIZE = sizeof(PATCH_MARKER) - 1;
+
+	if (meminfo.RegionSize < PATCH_MARKER_SIZE)
+	{
+		return false;
+	}
+
+	for (size_t i = 0; i <= meminfo.RegionSize - PATCH_MARKER_SIZE; i++)
 	{
-		// Maybe sketchy to rely on GLE here
-		THROW_WINDOWS_ERROR(GetLastError(), "Failed to open setupapi.dll");
+		if (0 == memcmp((void*)((char*)bytes + i), PATCH_MARKER, PATCH_MARKER_SIZE))
+		{
+			return true;
+		}
 	}
 
-	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));
+	return false;
 }
 
 }