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Date: Sun, 11 May 2003 19:59:06 +0300 From: Pasi K?rkk?inen Subject: [PATCH] fix SDL OpenGL segfault with DRI/Mesa drivers and Glew Hello! The attached patch fixes a bug in SDL which causes SDL to crash in X11_GL_Shutdown() if you are using DRI/Mesa drivers AND glew (http://glew.sf.net). The bug is caused by a namespace collision affecting dlsym() to fetch wrong pointer for glXReleaseBuffersMESA() (uninitialized pointer from glew because the extension is NOT supported by the driver) and then SDL calling it in X11_GL_Shutdown(). SDL should check if the glXReleaseBuffersMESA() is really supported by the driver (from the extensions string) before calling it. Attached patch adds extension string parsing to check if glXReleaseBuffersMESA() is really supported (and this way prevents the segfault). Availability of the extensions should be _always_ checked from the extensions string rather than using dlsym()! Please add it to the next version of SDL. Thanks to gltron and author of glew to help fixing this.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 28 Jun 2003 17:27:33 +0000
parents f6ffac90895c
children 0f2029a70548
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif

#ifdef HAVE_OPENGL
#include <GL/glx.h>
#include <dlfcn.h>
#if defined(__OpenBSD__) && !defined(__ELF__)
#define dlsym(x,y) dlsym(x, "_" y)
#endif
#endif
#include "SDL_sysvideo.h"

struct SDL_PrivateGLData {
    int gl_active; /* to stop switching drivers while we have a valid context */

#ifdef HAVE_OPENGL
    GLXContext glx_context;	/* Current GL context */
    XVisualInfo* glx_visualinfo; /* XVisualInfo* returned by glXChooseVisual */

    void * (*glXGetProcAddress)(const GLubyte *procName);

    XVisualInfo* (*glXChooseVisual)
		( Display*		dpy,
		  int			screen,
		  int*		attribList );

    GLXContext (*glXCreateContext)
		( Display*		dpy,
		  XVisualInfo*	vis,
		  GLXContext		shareList,
		  Bool		direct );

    void (*glXDestroyContext)
		( Display* 		dpy,
		  GLXContext		ctx );

    Bool (*glXMakeCurrent)
		( Display*		dpy,
		  GLXDrawable		drawable,
		  GLXContext		ctx );

    void (*glXSwapBuffers)
		( Display*		dpy,
		  GLXDrawable		drawable );

    int (*glXGetConfig)
	 ( Display* dpy,
	   XVisualInfo* visual_info,
	   int attrib,
	   int* value );

    void (*glXReleaseBuffersMESA)
	 ( Display* dpy,
	   GLXDrawable drawable );

    const char (*glXQueryExtensionsString)
	    ( Display* dpy,
	      int screen);

    
#endif /* HAVE_OPENGL */
};

/* Old variable names */
#define gl_active		(this->gl_data->gl_active)
#define glx_context		(this->gl_data->glx_context)
#define glx_visualinfo		(this->gl_data->glx_visualinfo)

/* OpenGL functions */
extern XVisualInfo *X11_GL_GetVisual(_THIS);
extern int X11_GL_CreateWindow(_THIS, int w, int h);
extern int X11_GL_CreateContext(_THIS);
extern void X11_GL_Shutdown(_THIS);
#ifdef HAVE_OPENGL
extern int X11_GL_MakeCurrent(_THIS);
extern int X11_GL_GetAttribute(_THIS, SDL_GLattr attrib, int* value);
extern void X11_GL_SwapBuffers(_THIS);
extern int X11_GL_LoadLibrary(_THIS, const char* path);
extern void *X11_GL_GetProcAddress(_THIS, const char* proc);
#endif
extern void X11_GL_UnloadLibrary(_THIS);