Handle hwnd and tbi when passing NULL

[András Kovács]

---
 dlls/user32/nonclient.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/dlls/user32/nonclient.c b/dlls/user32/nonclient.c
index 708ed80..dc3721a 100644
--- a/dlls/user32/nonclient.c
+++ b/dlls/user32/nonclient.c
@@ -1628,6 +1628,18 @@ BOOL WINAPI GetTitleBarInfo(HWND hwnd, PTITLEBARINFO tbi) {
 
     TRACE("(%p %p)\n", hwnd, tbi);
 
+    if (IsWindow(hwnd) == FALSE) {
+        TRACE("Invalid hwnd.\n");
+        SetLastError(ERROR_INVALID_WINDOW_HANDLE);
+        return FALSE;
+    }
+
+    if (!tbi) {
+        TRACE("tbi is NULL.\n");
+        SetLastError(ERROR_NOACCESS);
+        return FALSE;
+    }
+
     if(tbi->cbSize != sizeof(TITLEBARINFO)) {
         TRACE("Invalid TITLEBARINFO size: %d\n", tbi->cbSize);
         SetLastError(ERROR_INVALID_PARAMETER);
-- 
1.6.0.4


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