From 30f45ce5f7d639dd5a0b60f544b3535e3bc2105d Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 22 Sep 2009 15:15:47 +0100
Subject: [gl] Handle an absent visual.

If we cannot find the correct visual for the fbconfig, return an error
instead of crashing. The difference is subtle, granted.
---
 src/cairo-gl-surface.c  | 8 ++++++++
 src/cairo-glx-context.c | 7 ++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/cairo-gl-surface.c b/src/cairo-gl-surface.c
index e73646ae..17bf4bc5 100644
--- a/src/cairo-gl-surface.c
+++ b/src/cairo-gl-surface.c
@@ -61,6 +61,11 @@ static const cairo_gl_context_t _nil_context = {
     CAIRO_STATUS_NO_MEMORY
 };
 
+static const cairo_gl_context_t _nil_context__invalid_format = {
+    CAIRO_REFERENCE_COUNT_INVALID,
+    CAIRO_STATUS_INVALID_FORMAT
+};
+
 static cairo_bool_t _cairo_surface_is_gl (cairo_surface_t *surface)
 {
     return surface->backend == &_cairo_gl_surface_backend;
@@ -72,6 +77,9 @@ _cairo_gl_context_create_in_error (cairo_status_t status)
     if (status == CAIRO_STATUS_NO_MEMORY)
 	return (cairo_gl_context_t *) &_nil_context;
 
+    if (status == CAIRO_STATUS_INVALID_FORMAT)
+	return (cairo_gl_context_t *) &_nil_context__invalid_format;
+
     ASSERT_NOT_REACHED;
     return NULL;
 }
diff --git a/src/cairo-glx-context.c b/src/cairo-glx-context.c
index 18fe2297..b442a1fc 100644
--- a/src/cairo-glx-context.c
+++ b/src/cairo-glx-context.c
@@ -99,8 +99,6 @@ _glx_dummy_ctx (Display *dpy, GLXContext gl_ctx, Window *dummy)
     Window win = None;
     int cnt;
 
-    cairo_status_t status = CAIRO_STATUS_SUCCESS;
-
     /* Create a dummy window created for the target GLX context that we can
      * use to query the available GL/GLX extensions.
      */
@@ -114,6 +112,9 @@ _glx_dummy_ctx (Display *dpy, GLXContext gl_ctx, Window *dummy)
     vi = glXGetVisualFromFBConfig (dpy, config[0]);
     XFree (config);
 
+    if (unlikely (vi == NULL))
+	return _cairo_error (CAIRO_STATUS_INVALID_FORMAT);
+
     cmap = XCreateColormap (dpy,
 			    RootWindow (dpy, vi->screen),
 			    vi->visual,
@@ -136,7 +137,7 @@ _glx_dummy_ctx (Display *dpy, GLXContext gl_ctx, Window *dummy)
     }
 
     *dummy = win;
-    return status;
+    return CAIRO_STATUS_SUCCESS;
 }
 
 cairo_gl_context_t *
-- 
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