cache wuaueng.dll path

cuts down on redundant registry reads, which should slightly increase
performance of service starts

wufuc/core.h

@@ -1,7 +1,7 @@
 #pragma once
 
 DWORD WINAPI NewThreadProc(LPVOID lpParam);
-BOOL PatchWUAgentHMODULE(HMODULE hModule);
+BOOL PatchWU(HMODULE hModule);
 
 HMODULE WINAPI _LoadLibraryExA(
     _In_       LPCSTR  lpFileName,

wufuc/service.c

@@ -5,6 +5,9 @@
 #include "shellapihelper.h"
 #include "service.h"
 
+static CHAR wuauservdllA[MAX_PATH];
+static WCHAR wuauservdllW[MAX_PATH];
+
 BOOL get_svcdllA(LPCSTR lpServiceName, LPSTR lpServiceDll, DWORD dwSize) {
     CHAR lpSubKey[257];
     sprintf_s(lpSubKey, _countof(lpSubKey), "SYSTEM\\CurrentControlSet\\services\\%s\\Parameters", lpServiceName);
@@ -27,6 +30,20 @@ BOOL get_svcdllW(LPCWSTR lpServiceName, LPWSTR lpServiceDll, DWORD dwSize) {
     return TRUE;
 }
 
+LPSTR get_wuauservdllA(void) {
+    if (wuauservdllA[0] == '\0') {
+        get_svcdllA("wuauserv", wuauservdllA, _countof(wuauservdllA));
+    }
+    return wuauservdllA;
+}
+
+LPWSTR get_wuauservdllW(void) {
+    if (wuauservdllW[0] == L'\0') {
+        get_svcdllW(L"wuauserv", wuauservdllW, _countof(wuauservdllW));
+    }
+    return wuauservdllW;
+}
+
 BOOL get_svcpid(SC_HANDLE hSCManager, LPCTSTR lpServiceName, DWORD *lpdwProcessId) {
     SC_HANDLE hService = OpenService(hSCManager, lpServiceName, SERVICE_QUERY_STATUS);
     if (!hService) {

wufuc/service.h

@@ -6,9 +6,13 @@ BOOL get_svcpid(SC_HANDLE hSCManager, LPCTSTR lpServiceName, DWORD *lpdwProcessI
 BOOL get_svcgname(SC_HANDLE hSCManager, LPCTSTR lpServiceName, LPTSTR lpGroupName, SIZE_T dwSize);
 BOOL get_svcpath(SC_HANDLE hSCManager, LPCTSTR lpServiceName, LPTSTR lpBinaryPathName, SIZE_T dwSize);
 BOOL get_svcgpid(SC_HANDLE hSCManager, LPTSTR lpServiceGroupName, DWORD *lpdwProcessId);
+LPSTR get_wuauservdllA(void);
+LPWSTR get_wuauservdllW(void);
 
 #ifdef UNICODE
 #define get_svcdll get_svcdllW
+#define get_wuauservdll get_wuauservdllW
 #else
 #define get_svcdll get_svcdllA
+#define get_wuauservdll get_wuauservdllA
 #endif