[RPCRT4] Fix buffer size calculation bug when unions of pointers are used in RPC interfaces

The size of the transfer buffer was always too small when a parameter of a
function was a pointer to a union of pointers. The buffer size calculation
function for the union only returned the size of the data the the pointer
in the union pointed to, omitting the size of the data for the union itself.
This caused a buffer overrun in the following marshal step which makes the
RPC call fail.

This fix will enable us to remove some workarounds in our RPC interfaces.

Author: EricKohl

dll/win32/rpcrt4/ndr_marshall.c

@@ -5904,7 +5904,11 @@ static void union_arm_buffer_size(PMIDL_STUB_MESSAGE pStubMsg,
                         ERR("BufferLength == 0??\n");
                     PointerBufferSize(pStubMsg, *(unsigned char **)pMemory, desc);
                     pStubMsg->PointerLength = pStubMsg->BufferLength;
+#ifdef __REACTOS__
+                    pStubMsg->BufferLength += saved_buffer_length;
+#else
                     pStubMsg->BufferLength = saved_buffer_length;
+#endif
                 }
                 break;
             case FC_IP:

dll/win32/rpcrt4/rpcrt4_ros.diff

@@ -49,7 +49,22 @@ diff -pudN e:\wine\dlls\rpcrt4/cstub.c e:\reactos\dll\win32\rpcrt4/cstub.c
  #else
 
  #warning You must implement delegated proxies/stubs for your CPU
-
+diff --git "a/dll/win32/rpcrt4/ndr_marshall.c" "b/dll/win32/rpcrt4/ndr_marshall.c"
+index 764b304a047..5fdc1dbd106 100644
+--- "a/dll/win32/rpcrt4/ndr_marshall.c"
++++ "b/dll/win32/rpcrt4/ndr_marshall.c"
+@@ -5904,7 +5904,11 @@ static void union_arm_buffer_size(PMIDL_STUB_MESSAGE pStubMsg,
+                         ERR("BufferLength == 0??\n");
+                     PointerBufferSize(pStubMsg, *(unsigned char **)pMemory, desc);
+                     pStubMsg->PointerLength = pStubMsg->BufferLength;
++#ifdef __REACTOS__
++                    pStubMsg->BufferLength += saved_buffer_length;
++#else
+                     pStubMsg->BufferLength = saved_buffer_length;
++#endif
+                 }
+                 break;
+             case FC_IP:
 diff -pudN e:\wine\dlls\rpcrt4/rpc_epmap.c e:\reactos\dll\win32\rpcrt4/rpc_epmap.c
 --- e:\wine\dlls\rpcrt4/rpc_epmap.c	2016-11-16 17:29:34 +0100
 +++ e:\reactos\dll\win32\rpcrt4/rpc_epmap.c	2016-11-17 12:09:06 +0100