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mutter-performance-source/cogl/cogl-feature-private.c
Neil Roberts df77e8565e Don't use eglGetProcAddress to retrieve core functions
According to the EGL spec, eglGetProcAddress should only be used to
retrieve extension functions. It also says that returning non-NULL
does not mean the extension is available so you could interpret this
as saying that the function is allowed to return garbage for core
functions. This seems to happen at least for the Android
implementation of EGL.

To workaround this the winsys's are now passed down a flag to say
whether the function is from the core API. This information is already
in the gl-prototypes headers as the minimum core GL version and as a
pair of flags to specify whether it is available in core GLES1 and
GLES2. If the function is in core the EGL winsys will now avoid using
eglGetProcAddress and always fallback to querying the library directly
with the GModule API.

The GLX winsys is left alone because glXGetProcAddress apparently
supports querying core API and extension functions.

The WGL winsys could ideally be changed because wglGetProcAddress
should also only be used for extension functions but the situation is
slightly different because WGL considers anything from GL > 1.1 to be
an extension so it would need a bit more information to determine
whether to query the function directly from the library.

The SDL winsys is also left alone because it's not as easy to portably
determine which GL library SDL has chosen to load in order to resolve
the symbols directly.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 72089730ad06ccdd38a344279a893965ae68cec1)

  Since we aren't able to break API on the 1.12 branch
  cogl_get_proc_address is still supported but isn't easily able to
  determine whether the given name corresponds to a core symbol or
  not.  For now we just assume the symbol being queried isn't part
  of the core GL api and update the documentation accordingly.
2012-08-06 14:27:45 +01:00

205 lines
6.9 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-context-private.h"
#include "cogl-feature-private.h"
#include "cogl-renderer-private.h"
CoglBool
_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;
CoglBool in_core;
/* 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 = "";
in_core = TRUE;
}
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;
}
}
in_core = FALSE;
}
/* 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,
in_core);
g_free (full_function_name);
if (func == NULL)
goto error;
/* Set the function pointer in the context */
*(void **) ((uint8_t *) 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 **) ((uint8_t *) 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 "gl-prototypes/cogl-all-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 "gl-prototypes/cogl-all-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);
}