[PATCH] combase: Execute local server for correct architecture in a WoW64 setup.

[Dmitry Timoshkov]

Based on implementation of create_surrogate_server().

This patch makes 64-bit application work with its own shipped 32-bit COM server.

Signed-off-by: Dmitry Timoshkov 
---
 dlls/combase/rpc.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/dlls/combase/rpc.c b/dlls/combase/rpc.c
index 80760ca37e7..53cb32e08e2 100644
--- a/dlls/combase/rpc.c
+++ b/dlls/combase/rpc.c
@@ -478,6 +478,9 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)
 {
     static const WCHAR  embeddingW[] = L" -Embedding";
     HKEY                key;
+    int                 arch = (sizeof(void *) > sizeof(int)) ? 64 : 32;
+    REGSAM              opposite = (arch == 64) ? KEY_WOW64_32KEY : KEY_WOW64_64KEY;
+    BOOL                is_wow64 = FALSE;
     HRESULT             hr;
     WCHAR               command[MAX_PATH + ARRAY_SIZE(embeddingW)];
     DWORD               size = (MAX_PATH+1) * sizeof(WCHAR);
@@ -485,7 +488,11 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)
     PROCESS_INFORMATION pinfo;
     LONG ret;

+    TRACE("Attempting to start server for %s\n", debugstr_guid(rclsid));
+
     hr = open_key_for_clsid(rclsid, L"LocalServer32", KEY_READ, &key);
+    if (FAILED(hr) && (arch == 64 || (IsWow64Process(GetCurrentProcess(), &is_wow64) && is_wow64)))
+        hr = open_key_for_clsid(rclsid, L"LocalServer32", opposite | KEY_READ, &key);
     if (FAILED(hr))
     {
         ERR("class %s not registered\n", debugstr_guid(rclsid));
@@ -511,7 +518,19 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)

/* FIXME: Win2003 supports a ServerExecutable value that is passed into
      * CreateProcess */
-    if (!CreateProcessW(NULL, command, NULL, NULL, FALSE, DETACHED_PROCESS, NULL, NULL, &sinfo, &pinfo))
+    if (is_wow64 && arch == 64)
+    {
+        void *cookie;
+        Wow64DisableWow64FsRedirection(&cookie);
+        if (!CreateProcessW(NULL, command, NULL, NULL, FALSE, DETACHED_PROCESS, NULL, NULL, &sinfo, &pinfo))
+        {
+            WARN("failed to run local server %s\n", debugstr_w(command));
+            hr = HRESULT_FROM_WIN32(GetLastError());
+        }
+        Wow64RevertWow64FsRedirection(cookie);
+        if (FAILED(hr)) return hr;
+    }
+    else if (!CreateProcessW(NULL, command, NULL, NULL, FALSE, DETACHED_PROCESS, NULL, NULL, &sinfo, &pinfo))
     {
         WARN("failed to run local server %s\n", debugstr_w(command));
         return HRESULT_FROM_WIN32(GetLastError());

[Huw Davies]

On Tue, Apr 26, 2022 at 03:40:05PM +0300, Dmitry Timoshkov wrote:
> @@ -485,7 +488,11 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)
>      PROCESS_INFORMATION pinfo;
>      LONG ret;
> - TRACE("Attempting to start server for %s\n", debugstr_guid(rclsid));
> - hr = open_key_for_clsid(rclsid, L"LocalServer32", KEY_READ, &key);
> - if (FAILED(hr) && (arch == 64 || (IsWow64Process(GetCurrentProcess(), &is_wow64) && is_wow64)))
> -
>    hr = open_key_for_clsid(rclsid, L"LocalServer32", opposite | KEY_READ, &key);
> if (FAILED(hr))
>    {
>        ERR("class %s not registered\n", debugstr_guid(rclsid));
>
> @@ -511,7 +518,19 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)
>  /* FIXME: Win2003 supports a ServerExecutable value that is passed into
>   * CreateProcess */
> - if (!CreateProcessW(NULL, command, NULL, NULL, FALSE, DETACHED_PROCESS, NULL, NULL, &sinfo, &pinfo))
> - if (is_wow64 && arch == 64)

I'm confused, how can this condition ever be true?

Some tests for this would help.  It's a bit hard to do, but not
impossible.

Huw.

[Dmitry Timoshkov]

Hi Huw,

many thanks for the review.

Huw Davies  wrote:
> On Tue, Apr 26, 2022 at 03:40:05PM +0300, Dmitry Timoshkov wrote:
> > @@ -485,7 +488,11 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)
> >      PROCESS_INFORMATION pinfo;
> >      LONG ret;
> > - TRACE("Attempting to start server for %s\n", debugstr_guid(rclsid));
> > - hr = open_key_for_clsid(rclsid, L"LocalServer32", KEY_READ, &key);
> > - if (FAILED(hr) && (arch == 64 || (IsWow64Process(GetCurrentProcess(), &is_wow64) && is_wow64)))
> > -
> >    hr = open_key_for_clsid(rclsid, L"LocalServer32", opposite | KEY_READ, &key);
> > if (FAILED(hr))
> >    {
> >        ERR("class %s not registered\n", debugstr_guid(rclsid));
> >
> > @@ -511,7 +518,19 @@ static HRESULT create_server(REFCLSID rclsid, HANDLE *process)
> >  /* FIXME: Win2003 supports a ServerExecutable value that is passed into
> >   * CreateProcess */
> > - if (!CreateProcessW(NULL, command, NULL, NULL, FALSE, DETACHED_PROCESS, NULL, NULL, &sinfo, &pinfo))
> > - if (is_wow64 && arch == 64)
>
> I'm confused, how can this condition ever be true?
>
> Some tests for this would help.  It's a bit hard to do, but not
> impossible.

Looks like this is a typo, it should be 'if (is_wow64 || arch == 64)'.
Same typo slipped into create_surrogate_server().