From 1201c9f346f1e9b2bc00b0a9854fc6e182e851ef Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 3 Nov 2020 02:09:00 +0100
Subject: api: ensure more code compiles by using dead code elimination

It'd be nicer to do this via

if (is_defined(HAVE_WHATEVER))

But MSVC won't work with the linux kernel macros for this. Ongoing
research.

Nevertheless, this makes most of the program always pass through the
compiler's type checker, only to have dead code removed later.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 api/adapter.c | 35 +++++++++++++----------------------
 1 file changed, 13 insertions(+), 22 deletions(-)

(limited to 'api/adapter.c')

diff --git a/api/adapter.c b/api/adapter.c
index 0579e8b..642f842 100644
--- a/api/adapter.c
+++ b/api/adapter.c
@@ -340,7 +340,8 @@ EnableAllOurAdapters(_In_ HDEVINFO DevInfo, _In_ SP_DEVINFO_DATA_LIST *AdaptersT
 void
 AdapterInit(void)
 {
-#ifdef MAYBE_WOW64
+    if (!MAYBE_WOW64)
+        return;
     typedef BOOL(WINAPI * IsWow64Process2_t)(
         _In_ HANDLE hProcess, _Out_ USHORT * pProcessMachine, _Out_opt_ USHORT * pNativeMachine);
     HANDLE Kernel32;
@@ -354,7 +355,6 @@ AdapterInit(void)
         NativeMachine =
             IsWow64Process(GetCurrentProcess(), &IsWoW64) && IsWoW64 ? IMAGE_FILE_MACHINE_AMD64 : IMAGE_FILE_PROCESS;
     }
-#endif
 }
 
 static BOOL
@@ -801,13 +801,13 @@ RtlGetNtVersionNumbers(_Out_opt_ DWORD *MajorVersion, _Out_opt_ DWORD *MinorVers
 static BOOL
 HaveWHQL(void)
 {
-#if defined(HAVE_WHQL)
-    DWORD MajorVersion;
-    RtlGetNtVersionNumbers(&MajorVersion, NULL, NULL);
-    return MajorVersion >= 10;
-#else
+    if (HAVE_WHQL)
+    {
+        DWORD MajorVersion;
+        RtlGetNtVersionNumbers(&MajorVersion, NULL, NULL);
+        return MajorVersion >= 10;
+    }
     return FALSE;
-#endif
 }
 
 static WINTUN_STATUS
@@ -1682,15 +1682,10 @@ WintunCreateAdapter(
         RebootRequired = &DummyRebootRequired;
     *RebootRequired = FALSE;
     DWORD Result;
-#ifdef MAYBE_WOW64
-    if (NativeMachine != IMAGE_FILE_PROCESS)
-    {
+    if (MAYBE_WOW64 && NativeMachine != IMAGE_FILE_PROCESS)
         Result = CreateAdapterViaRundll32(Pool, Name, RequestedGUID, Adapter, RebootRequired);
-        RevertToSelf();
-        return Result;
-    }
-#endif
-    Result = CreateAdapter(Pool, Name, RequestedGUID, Adapter, RebootRequired);
+    else
+        Result = CreateAdapter(Pool, Name, RequestedGUID, Adapter, RebootRequired);
     RevertToSelf();
     return Result;
 }
@@ -1706,14 +1701,12 @@ WintunDeleteAdapter(_In_ const WINTUN_ADAPTER *Adapter, _In_ BOOL ForceCloseSess
         RebootRequired = &DummyRebootRequired;
     *RebootRequired = FALSE;
     DWORD Result;
-#ifdef MAYBE_WOW64
-    if (NativeMachine != IMAGE_FILE_PROCESS)
+    if (MAYBE_WOW64 && NativeMachine != IMAGE_FILE_PROCESS)
     {
         Result = DeleteAdapterViaRundll32(Adapter, ForceCloseSessions, RebootRequired);
         RevertToSelf();
         return Result;
     }
-#endif
 
     HDEVINFO DevInfo;
     SP_DEVINFO_DATA DevInfoData;
@@ -1796,14 +1789,12 @@ WintunDeleteDriver(void)
 
     DWORD Result = ERROR_SUCCESS;
 
-#ifdef MAYBE_WOW64
-    if (NativeMachine != IMAGE_FILE_PROCESS)
+    if (MAYBE_WOW64 && NativeMachine != IMAGE_FILE_PROCESS)
     {
         Result = DeleteDriverViaRundll32();
         RevertToSelf();
         return Result;
     }
-#endif
 
     /* DeleteAllOurAdapters(); */
     HANDLE DriverInstallationLock = NamespaceTakeDriverInstallationMutex();
-- 
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