[PATCH 1/2] msi: Execute the custom action server with the correct bitness.

[Zebediah Figura]

The bitness depends solely on the bitness of the DLL (tested manually).

Fixes bugs 31741 and 37856.

Signed-off-by: Zebediah Figura 
---
 dlls/msi/custom.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/dlls/msi/custom.c b/dlls/msi/custom.c
index 72c3efd..4ec1a39 100644
--- a/dlls/msi/custom.c
+++ b/dlls/msi/custom.c
@@ -579,11 +579,19 @@ UINT __wine_msi_call_dll_function(const GUID *guid)

static DWORD WINAPI DllThread( LPVOID arg )
 {
-    WCHAR buffer[64] = {'m','s','i','e','x','e','c','.','e','x','e',' ','-','E','m','b','e','d','d','i','n','g',' ',0};
+    static const WCHAR msiexec32W[] = {'C',':','/','w','i','n','d','o','w','s','/',
+        's','y','s','w','o','w','6','4','/','m','s','i','e','x','e','c','.','e','x','e',0};
+    static const WCHAR msiexecW[] = {'m','s','i','e','x','e','c','.','e','x','e',0};
+    static const WCHAR embeddingW[] = {' ','-','E','m','b','e','d','d','i','n','g',' ',0};
+    msi_custom_action_info *info;
     PROCESS_INFORMATION pi = {0};
     STARTUPINFOW si = {0};
+    WCHAR buffer[100];
     RPC_STATUS status;
     GUID *guid = arg;
+    void *cookie;
+    BOOL wow64;
+    DWORD arch;
     DWORD rc;

TRACE("custom action (%x) started\n", GetCurrentThreadId() );
@@ -605,8 +613,25 @@ static DWORD WINAPI DllThread( LPVOID arg )
         return status;
     }

+    info = find_action_by_guid(guid);
+    GetBinaryTypeW(info->source, &arch);
+
+    if (sizeof(void *) == 8 && arch == SCS_32BIT_BINARY)
+        strcpyW(buffer, msiexec32W);
+    else
+        strcpyW(buffer, msiexecW);
+    strcatW(buffer, embeddingW);
     StringFromGUID2(guid, buffer + strlenW(buffer), 39);
-    CreateProcessW(NULL, buffer, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
+
+    if (IsWow64Process(GetCurrentProcess(), &wow64) && wow64 && arch == SCS_64BIT_BINARY)
+    {
+        Wow64DisableWow64FsRedirection(&cookie);
+        CreateProcessW(NULL, buffer, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
+        Wow64RevertWow64FsRedirection(cookie);
+    }
+    else
+        CreateProcessW(NULL, buffer, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
+
     WaitForSingleObject(pi.hProcess, INFINITE);
     GetExitCodeProcess(pi.hProcess, &rc);
     CloseHandle(pi.hProcess);