[1/5] server: Check winstation visibility in server to avoid race-conditions.

[Sebastian Lackner]

GetDesktopWindow incorrectly assumes, that the process window station is
still the same one, which was used earlier when changing the desktop.
By moving the visibility check to wineserver we can also avoid wineserver
roundtrip for invisible desktops.

Signed-off-by: Sebastian Lackner <sebastian at fds-team.de>
---

The purpose of this series is to fix various race-conditions related to
winstation and desktop handling. After all patches are applied, winstation
tests do not longer produce "Application tried to create window ..." error
messages, and explorer.exe processes are no longer leaked. Originally I was
planning to write tests as a more convincing argument, but as it turned out,
there are much more bugs in the Wine implementation... so I'll defer that
till after the release, and only send the most critical fixes right now.

 dlls/user32/win.c |   72 ++++++++++++++++++++++++------------------------------
 server/window.c   |    8 ++++--
 2 files changed, 39 insertions(+), 41 deletions(-)

diff --git a/dlls/user32/win.c b/dlls/user32/win.c
index b81c22d..360834e 100644
--- a/dlls/user32/win.c
+++ b/dlls/user32/win.c
@@ -2033,45 +2033,39 @@ HWND WINAPI GetDesktopWindow(void)
 
     if (!thread_info->top_window)
     {
-        USEROBJECTFLAGS flags;
-        if (!GetUserObjectInformationW( GetProcessWindowStation(), UOI_FLAGS, &flags,
-                                        sizeof(flags), NULL ) || (flags.dwFlags & WSF_VISIBLE))
-        {
-            static const WCHAR explorer[] = {'\\','e','x','p','l','o','r','e','r','.','e','x','e',0};
-            static const WCHAR args[] = {' ','/','d','e','s','k','t','o','p',0};
-            STARTUPINFOW si;
-            PROCESS_INFORMATION pi;
-            WCHAR windir[MAX_PATH];
-            WCHAR app[MAX_PATH + sizeof(explorer)/sizeof(WCHAR)];
-            WCHAR cmdline[MAX_PATH + (sizeof(explorer) + sizeof(args))/sizeof(WCHAR)];
-            void *redir;
-
-            memset( &si, 0, sizeof(si) );
-            si.cb = sizeof(si);
-            si.dwFlags = STARTF_USESTDHANDLES;
-            si.hStdInput  = 0;
-            si.hStdOutput = 0;
-            si.hStdError  = GetStdHandle( STD_ERROR_HANDLE );
-
-            GetSystemDirectoryW( windir, MAX_PATH );
-            strcpyW( app, windir );
-            strcatW( app, explorer );
-            strcpyW( cmdline, app );
-            strcatW( cmdline, args );
-
-            Wow64DisableWow64FsRedirection( &redir );
-            if (CreateProcessW( app, cmdline, NULL, NULL, FALSE, DETACHED_PROCESS,
-                                NULL, windir, &si, &pi ))
-            {
-                TRACE( "started explorer pid %04x tid %04x\n", pi.dwProcessId, pi.dwThreadId );
-                WaitForInputIdle( pi.hProcess, 10000 );
-                CloseHandle( pi.hThread );
-                CloseHandle( pi.hProcess );
-            }
-            else WARN( "failed to start explorer, err %d\n", GetLastError() );
-            Wow64RevertWow64FsRedirection( redir );
-        }
-        else TRACE( "not starting explorer since winstation is not visible\n" );
+        static const WCHAR explorer[] = {'\\','e','x','p','l','o','r','e','r','.','e','x','e',0};
+        static const WCHAR args[] = {' ','/','d','e','s','k','t','o','p',0};
+        STARTUPINFOW si;
+        PROCESS_INFORMATION pi;
+        WCHAR windir[MAX_PATH];
+        WCHAR app[MAX_PATH + sizeof(explorer)/sizeof(WCHAR)];
+        WCHAR cmdline[MAX_PATH + (sizeof(explorer) + sizeof(args))/sizeof(WCHAR)];
+        void *redir;
+
+        memset( &si, 0, sizeof(si) );
+        si.cb = sizeof(si);
+        si.dwFlags = STARTF_USESTDHANDLES;
+        si.hStdInput  = 0;
+        si.hStdOutput = 0;
+        si.hStdError  = GetStdHandle( STD_ERROR_HANDLE );
+
+        GetSystemDirectoryW( windir, MAX_PATH );
+        strcpyW( app, windir );
+        strcatW( app, explorer );
+        strcpyW( cmdline, app );
+        strcatW( cmdline, args );
+
+        Wow64DisableWow64FsRedirection( &redir );
+        if (CreateProcessW( app, cmdline, NULL, NULL, FALSE, DETACHED_PROCESS,
+                            NULL, windir, &si, &pi ))
+        {
+            TRACE( "started explorer pid %04x tid %04x\n", pi.dwProcessId, pi.dwThreadId );
+            WaitForInputIdle( pi.hProcess, 10000 );
+            CloseHandle( pi.hThread );
+            CloseHandle( pi.hProcess );
+        }
+        else WARN( "failed to start explorer, err %d\n", GetLastError() );
+        Wow64RevertWow64FsRedirection( redir );
 
         SERVER_START_REQ( get_desktop_window )
         {
diff --git a/server/window.c b/server/window.c
index d089149..5f32f1e 100644
--- a/server/window.c
+++ b/server/window.c
@@ -1953,10 +1953,14 @@ DECL_HANDLER(destroy_window)
 DECL_HANDLER(get_desktop_window)
 {
     struct desktop *desktop = get_thread_desktop( current, 0 );
+    int force;
 
     if (!desktop) return;
 
-    if (!desktop->top_window && req->force)  /* create it */
+    /* if winstation is invisible, then avoid roundtrip */
+    force = req->force || !(desktop->winstation->flags & WSF_VISIBLE);
+
+    if (!desktop->top_window && force)  /* create it */
     {
         if ((desktop->top_window = create_window( NULL, NULL, DESKTOP_ATOM, 0 )))
         {
@@ -1965,7 +1969,7 @@ DECL_HANDLER(get_desktop_window)
         }
     }
 
-    if (!desktop->msg_window && req->force)  /* create it */
+    if (!desktop->msg_window && force)  /* create it */
     {
         static const WCHAR messageW[] = {'M','e','s','s','a','g','e'};
         static const struct unicode_str name = { messageW, sizeof(messageW) };
-- 
2.6.2