[mutter] cogl/gl: Handle bogus glGetString(GL_RENDERER) return values

[Marge Bot <marge-bot src gnome org>]

commit e4375046e04111fb569ac1686233b40ba75849f7
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Jul 14 16:48:34 2021 +0200

    cogl/gl: Handle bogus glGetString(GL_RENDERER) return values
    
    Seems glGetString(GL_RENDERER) in the wild can return NULL, causing
    issues with strstr(). Handle this more gracefully by using
    g_return_val_if_fail(), that assumes a NULL renderer means software
    rendering.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1931>

 cogl/cogl/driver/gl/cogl-util-gl.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/cogl/cogl/driver/gl/cogl-util-gl.c b/cogl/cogl/driver/gl/cogl-util-gl.c
index 096fcb7886..80c4179130 100644
--- a/cogl/cogl/driver/gl/cogl-util-gl.c
+++ b/cogl/cogl/driver/gl/cogl-util-gl.c
@@ -460,6 +460,13 @@ _cogl_driver_gl_is_hardware_accelerated (CoglContext *ctx)
   const char *renderer = (const char *) ctx->glGetString (GL_RENDERER);
   gboolean software;
 
+  if (!renderer)
+    {
+      g_warning ("OpenGL driver returned NULL as the renderer, "
+                 "something is wrong");
+      return TRUE;
+    }
+
   software = strstr (renderer, "llvmpipe") != NULL ||
              strstr (renderer, "softpipe") != NULL ||
              strstr (renderer, "software rasterizer") != NULL ||