mutter/cogl/winsys/cogl-winsys-stub.c
Neil Roberts d259a87602 Don't use the 'NULL' GModule to resolve GL symbols
Previously, _cogl_get_proc_address had a fallback to resolve the
symbol using g_module_open(NULL) to get the symbol from anywhere in
the address space. The EGL backend ends up using this on some drivers
because eglGetProcAddress isn't meant to return a pointer for core
functions. This causes problems if something in the process is linking
against a different GL library, for example Cairo may be linking
against libGL itself. In this case it may end up resolving symbols
from the GL library even if GLES is being used.

This patch removes the fallback. The EGL version now has its own
fallback instead which passes the existing libgl_module from the
renderer to g_module_symbol so that it should only get symbols from
that library or its dependency chain. The GLX and WGL winsys only call
glXGetProcAddress and wglGetProcAddress. The stub winsys does however
continue using the global symbol lookup.

The internal _cogl_get_proc_address function has been renamed to
_cogl_renderer_get_proc_address because it needs a connected renderer
to work so it could be considered to be a renderer method. The pointer
to the renderer is passed down to the winsys backends so that it can
use the data attached to the renderer to get the module pointers.

https://bugzilla.gnome.org/show_bug.cgi?id=655412

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-07-27 16:10:02 +01:00

175 lines
4.2 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2011 Intel Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
*
* Authors:
* Robert Bragg <robert@linux.intel.com>
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl-renderer-private.h"
#include "cogl-display-private.h"
#include "cogl-context-private.h"
#include "cogl-framebuffer-private.h"
#include "cogl-private.h"
#include <string.h>
static int _cogl_winsys_stub_dummy_ptr;
/* This provides a NOP winsys. This can be useful for debugging or for
* integrating with toolkits that already have window system
* integration code.
*/
static CoglFuncPtr
_cogl_winsys_renderer_get_proc_address (CoglRenderer *renderer,
const char *name)
{
static GModule *module = NULL;
/* this should find the right function if the program is linked against a
* library providing it */
if (G_UNLIKELY (module == NULL))
module = g_module_open (NULL, 0);
if (module)
{
void *symbol;
if (g_module_symbol (module, name, &symbol))
return symbol;
}
return NULL;
}
static void
_cogl_winsys_renderer_disconnect (CoglRenderer *renderer)
{
renderer->winsys = NULL;
}
static gboolean
_cogl_winsys_renderer_connect (CoglRenderer *renderer,
GError **error)
{
renderer->winsys = &_cogl_winsys_stub_dummy_ptr;
return TRUE;
}
static void
_cogl_winsys_display_destroy (CoglDisplay *display)
{
display->winsys = NULL;
}
static gboolean
_cogl_winsys_display_setup (CoglDisplay *display,
GError **error)
{
display->winsys = &_cogl_winsys_stub_dummy_ptr;
return TRUE;
}
static gboolean
_cogl_winsys_context_init (CoglContext *context, GError **error)
{
context->winsys = &_cogl_winsys_stub_dummy_ptr;
if (!_cogl_context_update_features (context, error))
return FALSE;
memset (context->winsys_features, 0, sizeof (context->winsys_features));
return TRUE;
}
static void
_cogl_winsys_context_deinit (CoglContext *context)
{
context->winsys = NULL;
}
static gboolean
_cogl_winsys_onscreen_init (CoglOnscreen *onscreen,
GError **error)
{
return TRUE;
}
static void
_cogl_winsys_onscreen_deinit (CoglOnscreen *onscreen)
{
}
static void
_cogl_winsys_onscreen_bind (CoglOnscreen *onscreen)
{
}
static void
_cogl_winsys_onscreen_swap_buffers (CoglOnscreen *onscreen)
{
}
static void
_cogl_winsys_onscreen_update_swap_throttled (CoglOnscreen *onscreen)
{
}
static void
_cogl_winsys_onscreen_set_visibility (CoglOnscreen *onscreen,
gboolean visibility)
{
}
static CoglWinsysVtable _cogl_winsys_vtable =
{
.id = COGL_WINSYS_ID_STUB,
.name = "STUB",
.renderer_get_proc_address = _cogl_winsys_renderer_get_proc_address,
.renderer_connect = _cogl_winsys_renderer_connect,
.renderer_disconnect = _cogl_winsys_renderer_disconnect,
.display_setup = _cogl_winsys_display_setup,
.display_destroy = _cogl_winsys_display_destroy,
.context_init = _cogl_winsys_context_init,
.context_deinit = _cogl_winsys_context_deinit,
.onscreen_init = _cogl_winsys_onscreen_init,
.onscreen_deinit = _cogl_winsys_onscreen_deinit,
.onscreen_bind = _cogl_winsys_onscreen_bind,
.onscreen_swap_buffers = _cogl_winsys_onscreen_swap_buffers,
.onscreen_update_swap_throttled =
_cogl_winsys_onscreen_update_swap_throttled,
.onscreen_set_visibility = _cogl_winsys_onscreen_set_visibility,
};
const CoglWinsysVtable *
_cogl_winsys_stub_get_vtable (void)
{
return &_cogl_winsys_vtable;
}