From 4d619d9b17d2d8ef8538631fd81938e587387db1 Mon Sep 17 00:00:00 2001
From: baldurk <baldurk@baldurk.org>
Date: Fri, 17 Aug 2018 19:49:31 +0100
Subject: [PATCH] Only query fbconfig for valid non-NULL context. Closes #1082

---
 renderdoc/driver/gl/glx_hooks.cpp | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/renderdoc/driver/gl/glx_hooks.cpp b/renderdoc/driver/gl/glx_hooks.cpp
index b836e6248..49cdd16ab 100644
--- a/renderdoc/driver/gl/glx_hooks.cpp
+++ b/renderdoc/driver/gl/glx_hooks.cpp
@@ -367,18 +367,23 @@ HOOK_EXPORT Bool glXMakeContextCurrent(Display *dpy, GLXDrawable draw, GLXDrawab
     data.wnd = draw;
     data.ctx = ctx;
 
-    int fbconfigid = -1;
-    GLX.glXQueryContext(dpy, ctx, GLX_FBCONFIG_ID, &fbconfigid);
+    GLXFBConfig *config = NULL;
 
-    int attribs[] = {GLX_FBCONFIG_ID, fbconfigid, 0};
+    if(ctx)
+    {
+      int fbconfigid = -1;
+      GLX.glXQueryContext(dpy, ctx, GLX_FBCONFIG_ID, &fbconfigid);
 
-    int numElems = 0;
-    GLXFBConfig *config = GLX.glXChooseFBConfig(dpy, DefaultScreen(dpy), attribs, &numElems);
+      int attribs[] = {GLX_FBCONFIG_ID, fbconfigid, 0};
 
-    if(config)
-      data.cfg = GLX.glXGetVisualFromFBConfig(dpy, *config);
-    else
-      data.cfg = NULL;
+      int numElems = 0;
+      config = GLX.glXChooseFBConfig(dpy, DefaultScreen(dpy), attribs, &numElems);
+
+      if(config)
+        data.cfg = GLX.glXGetVisualFromFBConfig(dpy, *config);
+      else
+        data.cfg = NULL;
+    }
 
     glxhook.driver.ActivateContext(data);