dri3: Guard against buggy clients

There's nothing to stop a client from sending these requests to screens
without DRI3 support, and if they do, we'll crash.  Let's not do that.

Reviewed-by: Jasper St. Pierre <<jstpierre@mecheye.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>

diff --git a/dri3/dri3_screen.c b/dri3/dri3_screen.c
index cf2735b..c880296 100644 (file)
--- a/dri3/dri3_screen.c
+++ b/dri3/dri3_screen.c
@@ -55,6 +55,9 @@ dri3_pixmap_from_fd(PixmapPtr *ppixmap, ScreenPtr screen, int fd,
     dri3_screen_info_ptr        info = ds->info;
     PixmapPtr                   pixmap;
 
+    if (!info || !info->pixmap_from_fd)
+        return BadImplementation;
+
     pixmap = (*info->pixmap_from_fd) (screen, fd, width, height, stride, depth, bpp);
     if (!pixmap)
         return BadAlloc;
@@ -71,6 +74,9 @@ dri3_fd_from_pixmap(int *pfd, PixmapPtr pixmap, CARD16 *stride, CARD32 *size)
     dri3_screen_info_ptr        info = ds->info;
     int                         fd;
 
+    if (!info || !info->fd_from_pixmap)
+        return BadImplementation;
+
     fd = (*info->fd_from_pixmap)(screen, pixmap, stride, size);
     if (fd < 0)
         return BadAlloc;