From d301cadcb00a756a92ece4bec15f1ed2db035c2d Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Tue, 26 Aug 2008 02:47:26 +0000
Subject: [PATCH] Couriersud fixed bug #603

Using the following sequence

SDL_Init(..:)
SDL_CreateWindow(..., SDL_WINDOW_OPENGL)
SDL_DestroyWindow
SDL_CreateWindow(..., SDL_WINDOW_OPENGL)

SDL will crash in X11_GL_GetVisual. This is due to the fact that
during SDL_DestroyWindow X11_GL_Shutdown was called because the last window
has been closed.

On the next call to SDL_CreateWindow the library is still loaded and only the
memory is reinitialized. Function pointers such as gl_data->glXChooseVisual
will not be reinitialized.

Consequently, SDL will crash due to a NULL pointer access.

The attached patch corrects the behaviour.
---
 src/video/x11/SDL_x11opengl.c | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/src/video/x11/SDL_x11opengl.c b/src/video/x11/SDL_x11opengl.c
index 6e131e4ea..48323877e 100644
--- a/src/video/x11/SDL_x11opengl.c
+++ b/src/video/x11/SDL_x11opengl.c
@@ -73,26 +73,26 @@ X11_GL_LoadLibrary(_THIS, const char *path)
     void *handle;
 
     if (_this->gl_config.driver_loaded) {
+        /* do not return without reinitializing the function hooks */
         if (path) {
             SDL_SetError("OpenGL library already loaded");
+        }
+        handle = _this->gl_config.dll_handle;
+    } else {
+        if (path == NULL) {
+            path = SDL_getenv("SDL_OPENGL_LIBRARY");
+        }
+        if (path == NULL) {
+            path = DEFAULT_OPENGL;
+        }
+        handle = GL_LoadObject(path);
+        if (!handle) {
             return -1;
-        } else {
-            ++_this->gl_config.driver_loaded;
-            return 0;
         }
+        _this->gl_config.dll_handle = handle;
+        SDL_strlcpy(_this->gl_config.driver_path, path,
+                    SDL_arraysize(_this->gl_config.driver_path));
     }
-    if (path == NULL) {
-        path = SDL_getenv("SDL_OPENGL_LIBRARY");
-    }
-    if (path == NULL) {
-        path = DEFAULT_OPENGL;
-    }
-    handle = GL_LoadObject(path);
-    if (!handle) {
-        return -1;
-    }
-    // LoadLibrary may be called before WindowCreate!
-    // Must create the memory used by GL
     X11_GL_InitializeMemory(_this);
 
     /* Load new function pointers */
@@ -123,10 +123,7 @@ X11_GL_LoadLibrary(_THIS, const char *path)
         return -1;
     }
 
-    _this->gl_config.dll_handle = handle;
-    SDL_strlcpy(_this->gl_config.driver_path, path,
-                SDL_arraysize(_this->gl_config.driver_path));
-    _this->gl_config.driver_loaded = 1;
+    ++_this->gl_config.driver_loaded;
     return 0;
 }