From a506b4ecb6c54fd0388e628520eec75ea3bcb27c Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Wed, 6 Nov 2019 15:37:22 +0100
Subject: [PATCH] xwayland: make context current to check GL version
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`glGetString(GL_VERSION)` will return NULL without a current context.

Commit dabc7d8b (“xwayland: Fall back to GLES2 if we don't get at least
GL 2.1 in glamor”) would check the context is created, but it is made
current just after, so the call to `epoxy_gl_version()` would return 0,
hence defeating the version check.

Make the context current prior to call `epoxy_gl_version()`.

Fixes: dabc7d8b - xwayland: Fall back to GLES2 if we don't get at least
                  GL 2.1 in glamor
Closes: https://gitlab.freedesktop.org/xorg/xserver/issues/932
https://gitlab.freedesktop.org/xorg/xserver/merge_requests/324
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
---
 hw/xwayland/xwayland-glamor-gbm.c | 50 ++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/hw/xwayland/xwayland-glamor-gbm.c b/hw/xwayland/xwayland-glamor-gbm.c
index 2df12aeaa..bfcf81dbc 100644
--- a/hw/xwayland/xwayland-glamor-gbm.c
+++ b/hw/xwayland/xwayland-glamor-gbm.c
@@ -948,33 +948,49 @@ xwl_glamor_gbm_init_egl(struct xwl_screen *xwl_screen)
             xwl_screen->egl_display, NULL, EGL_NO_CONTEXT, NULL);
     }
 
-    /* glamor needs either big-GL 2.1 or GLES2 */
-    if (xwl_screen->egl_context && epoxy_gl_version() < 21) {
-        const EGLint gles_attribs[] = {
-            EGL_CONTEXT_CLIENT_VERSION,
-            2,
-            EGL_NONE,
-        };
-
-        eglDestroyContext(xwl_screen->egl_display, xwl_screen->egl_context);
-        eglBindAPI(EGL_OPENGL_ES_API);
-        xwl_screen->egl_context = eglCreateContext(xwl_screen->egl_display,
-                                                   NULL, EGL_NO_CONTEXT,
-                                                   gles_attribs);
-    }
-
     if (xwl_screen->egl_context == EGL_NO_CONTEXT) {
-        ErrorF("Failed to create EGL context\n");
+        ErrorF("Failed to create EGL context with GL\n");
         goto error;
     }
 
     if (!eglMakeCurrent(xwl_screen->egl_display,
                         EGL_NO_SURFACE, EGL_NO_SURFACE,
                         xwl_screen->egl_context)) {
-        ErrorF("Failed to make EGL context current\n");
+        ErrorF("Failed to make EGL context current with GL\n");
         goto error;
     }
 
+    /* glamor needs either big-GL 2.1 or GLES2 */
+    if (epoxy_gl_version() < 21) {
+        const EGLint gles_attribs[] = {
+            EGL_CONTEXT_CLIENT_VERSION,
+            2,
+            EGL_NONE,
+        };
+
+        /* Recreate the context with GLES2 instead */
+        eglMakeCurrent(xwl_screen->egl_display,EGL_NO_SURFACE,
+                       EGL_NO_SURFACE, EGL_NO_CONTEXT);
+        eglDestroyContext(xwl_screen->egl_display, xwl_screen->egl_context);
+
+        eglBindAPI(EGL_OPENGL_ES_API);
+        xwl_screen->egl_context = eglCreateContext(xwl_screen->egl_display,
+                                                   NULL, EGL_NO_CONTEXT,
+                                                   gles_attribs);
+
+        if (xwl_screen->egl_context == EGL_NO_CONTEXT) {
+            ErrorF("Failed to create EGL context with GLES2\n");
+            goto error;
+        }
+
+        if (!eglMakeCurrent(xwl_screen->egl_display,
+                            EGL_NO_SURFACE, EGL_NO_SURFACE,
+                            xwl_screen->egl_context)) {
+            ErrorF("Failed to make EGL context current with GLES2\n");
+            goto error;
+        }
+    }
+
     renderer = glGetString(GL_RENDERER);
     if (!renderer) {
         ErrorF("glGetString() returned NULL, your GL is broken\n");