Fix NULL function pointer BeginPaint

diff --git a/libfreerdp/gdi/gfx.c b/libfreerdp/gdi/gfx.c
index a5e427f..f15c53a 100644 (file)
--- a/libfreerdp/gdi/gfx.c
+++ b/libfreerdp/gdi/gfx.c
@@ -94,6 +94,7 @@ static UINT gdi_ResetGraphics(RdpgfxClientContext* context,
 
 static UINT gdi_OutputUpdate(rdpGdi* gdi, gdiGfxSurface* surface)
 {
+       UINT rc = ERROR_INTERNAL_ERROR;
        UINT32 nXDst, nYDst;
        UINT32 nXSrc, nYSrc;
        UINT16 width, height;
@@ -118,7 +119,8 @@ static UINT gdi_OutputUpdate(rdpGdi* gdi, gdiGfxSurface* surface)
        if (!(rects = region16_rects(&surface->invalidRegion, &nbRects)) || !nbRects)
                return CHANNEL_RC_OK;
 
-       update->BeginPaint(gdi->context);
+       if (!IFCALLRESULT(TRUE, update->BeginPaint, gdi->context))
+               goto fail;
 
        for (i = 0; i < nbRects; i++)
        {
@@ -139,9 +141,13 @@ static UINT gdi_OutputUpdate(rdpGdi* gdi, gdiGfxSurface* surface)
                gdi_InvalidateRegion(gdi->primary->hdc, nXDst, nYDst, width, height);
        }
 
-       update->EndPaint(gdi->context);
+       if (!IFCALLRESULT(FALSE, update->EndPaint, gdi->context))
+               goto fail;
+
+       rc = CHANNEL_RC_OK;
+fail:
        region16_clear(&(surface->invalidRegion));
-       return CHANNEL_RC_OK;
+       return rc;
 }
 
 static UINT gdi_UpdateSurfaces(RdpgfxClientContext* context)