mutter/cogl/cogl-feature-private.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

199 lines
6.7 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2009 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/>.
*
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include "cogl.h"
#include "cogl-context-private.h"
#include "cogl-feature-private.h"
#include "cogl-renderer-private.h"
gboolean
_cogl_feature_check (CoglRenderer *renderer,
const char *driver_prefix,
const CoglFeatureData *data,
int gl_major,
int gl_minor,
CoglDriver driver,
const char *extensions_string,
void *function_table)
{
const char *suffix = NULL;
int func_num;
/* First check whether the functions should be directly provided by
GL */
if ((driver == COGL_DRIVER_GL &&
COGL_CHECK_GL_VERSION (gl_major, gl_minor,
data->min_gl_major, data->min_gl_minor)) ||
(driver == COGL_DRIVER_GLES1 &&
(data->gles_availability & COGL_EXT_IN_GLES)) ||
(driver == COGL_DRIVER_GLES2 &&
(data->gles_availability & COGL_EXT_IN_GLES2)))
suffix = "";
else
{
/* Otherwise try all of the extensions */
const char *namespace, *namespace_suffix;
unsigned int namespace_len;
for (namespace = data->namespaces;
*namespace;
namespace += strlen (namespace) + 1)
{
const char *extension;
GString *full_extension_name = g_string_new ("");
/* If the namespace part contains a ':' then the suffix for
the function names is different from the name space */
if ((namespace_suffix = strchr (namespace, ':')))
{
namespace_len = namespace_suffix - namespace;
namespace_suffix++;
}
else
{
namespace_len = strlen (namespace);
namespace_suffix = namespace;
}
for (extension = data->extension_names;
*extension;
extension += strlen (extension) + 1)
{
g_string_assign (full_extension_name, driver_prefix);
g_string_append_c (full_extension_name, '_');
g_string_append_len (full_extension_name,
namespace, namespace_len);
g_string_append_c (full_extension_name, '_');
g_string_append (full_extension_name, extension);
if (_cogl_check_extension (full_extension_name->str,
extensions_string))
break;
}
g_string_free (full_extension_name, TRUE);
/* If we found an extension with this namespace then use it
as the suffix */
if (*extension)
{
suffix = namespace_suffix;
break;
}
}
}
/* If we couldn't find anything that provides the functions then
give up */
if (suffix == NULL)
goto error;
/* Try to get all of the entry points */
for (func_num = 0; data->functions[func_num].name; func_num++)
{
void *func;
char *full_function_name;
full_function_name = g_strconcat (data->functions[func_num].name,
suffix, NULL);
func = _cogl_renderer_get_proc_address (renderer, full_function_name);
g_free (full_function_name);
if (func == NULL)
goto error;
/* Set the function pointer in the context */
*(void **) ((guint8 *) function_table +
data->functions[func_num].pointer_offset) = func;
}
return TRUE;
/* If the extension isn't found or one of the functions wasn't found
* then set all of the functions pointers to NULL so Cogl can safely
* do feature testing by just looking at the function pointers */
error:
for (func_num = 0; data->functions[func_num].name; func_num++)
*(void **) ((guint8 *) function_table +
data->functions[func_num].pointer_offset) = NULL;
return FALSE;
}
/* Define a set of arrays containing the functions required from GL
for each feature */
#define COGL_EXT_BEGIN(name, \
min_gl_major, min_gl_minor, \
gles_availability, \
namespaces, extension_names) \
static const CoglFeatureFunction cogl_ext_ ## name ## _funcs[] = {
#define COGL_EXT_FUNCTION(ret, name, args) \
{ G_STRINGIFY (name), G_STRUCT_OFFSET (CoglContext, name) },
#define COGL_EXT_END() \
{ NULL, 0 }, \
};
#include "cogl-ext-functions.h"
/* Define an array of features */
#undef COGL_EXT_BEGIN
#define COGL_EXT_BEGIN(name, \
min_gl_major, min_gl_minor, \
gles_availability, \
namespaces, extension_names) \
{ min_gl_major, min_gl_minor, gles_availability, namespaces, \
extension_names, 0, 0, 0, \
cogl_ext_ ## name ## _funcs },
#undef COGL_EXT_FUNCTION
#define COGL_EXT_FUNCTION(ret, name, args)
#undef COGL_EXT_END
#define COGL_EXT_END()
static const CoglFeatureData
cogl_feature_ext_functions_data[] =
{
#include "cogl-ext-functions.h"
};
void
_cogl_feature_check_ext_functions (CoglContext *context,
int gl_major,
int gl_minor,
const char *gl_extensions)
{
int i;
for (i = 0; i < G_N_ELEMENTS (cogl_feature_ext_functions_data); i++)
_cogl_feature_check (context->display->renderer,
"GL", cogl_feature_ext_functions_data + i,
gl_major, gl_minor, context->driver,
gl_extensions,
context);
}