st/wgl: Return NULL for NULL HDCs in wglGetExtensionsStringARB.

WGL_ARB_extensions_string states that wglGetExtensionsStringARB should
return NULL for invalid HDCs.  And some applications rely on it.

Reviewed-By: "Keith Whitwell" <keithw@vmware.com>

diff --git a/src/gallium/state_trackers/wgl/stw_ext_extensionsstring.c b/src/gallium/state_trackers/wgl/stw_ext_extensionsstring.c
index ecb326f..7cad49c 100644 (file)
--- a/src/gallium/state_trackers/wgl/stw_ext_extensionsstring.c
+++ b/src/gallium/state_trackers/wgl/stw_ext_extensionsstring.c
@@ -47,7 +47,9 @@ WINGDIAPI const char * APIENTRY
 wglGetExtensionsStringARB(
    HDC hdc )
 {
-   (void) hdc;
+   if (!hdc) {
+      return NULL;
+   }
 
    return stw_extension_string;
 }