hhctrl: check for filename

[André Hentschel]

fixes Bug 19070
---
 dlls/hhctrl.ocx/hhctrl.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/dlls/hhctrl.ocx/hhctrl.c b/dlls/hhctrl.ocx/hhctrl.c
index 8268a21..76b5ac0 100644
--- a/dlls/hhctrl.ocx/hhctrl.c
+++ b/dlls/hhctrl.ocx/hhctrl.c
@@ -290,6 +290,8 @@ int WINAPI doWinMain(HINSTANCE hInstance, LPSTR szCmdLine)
     filename = heap_alloc(buflen * sizeof(WCHAR));
     MultiByteToWideChar(CP_ACP, 0, szCmdLine, len, filename, buflen);
     filename[buflen-1] = 0;
+    if(!*filename)
+        return 0;
 
     HtmlHelpW(GetDesktopWindow(), filename, HH_DISPLAY_TOPIC, 0);
 
-- 

Best Regards, André Hentschel