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glxtest.cpp
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glxtest.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=8 et :
*/
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at:
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Code.
*
* The Initial Developer of the Original Code is
* The Mozilla Foundation
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
//////////////////////////////////////////////////////////////////////////////
//
// Explanation: See bug 639842. Safely getting GL driver info on X11 is hard, because the only way to do
// that is to create a GL context and call glGetString(), but with bad drivers,
// just creating a GL context may crash.
//
// This file implements the idea to do that in a separate process.
//
// The only non-static function here is fire_glxtest_process(). It creates a pipe, publishes its 'read' end as the
// mozilla::widget::glxtest_pipe global variable, forks, and runs that GLX probe in the child process,
// which runs the glxtest() static function. This creates a X connection, a GLX context, calls glGetString, and writes that
// to the 'write' end of the pipe.
#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <GL/gl.h>
#include <GL/glx.h>
#include <dlfcn.h>
#include "nscore.h"
namespace mozilla {
namespace widget {
// the read end of the pipe, which will be used by GfxInfo
extern int glxtest_pipe;
// the PID of the glxtest process, to pass to waitpid()
extern pid_t glxtest_pid;
}
}
// the write end of the pipe, which we're going to write to
static int write_end_of_the_pipe = -1;
// C++ standard collides with C standard in that it doesn't allow casting void* to function pointer types.
// So the work-around is to convert first to size_t.
// http://www.trilithium.com/johan/2004/12/problem-with-dlsym/
template<typename func_ptr_type>
static func_ptr_type cast(void *ptr)
{
return reinterpret_cast<func_ptr_type>(
reinterpret_cast<size_t>(ptr)
);
}
static void fatal_error(const char *str)
{
write(write_end_of_the_pipe, str, strlen(str));
write(write_end_of_the_pipe, "\n", 1);
exit(EXIT_FAILURE);
}
static int
x_error_handler(Display *, XErrorEvent *ev)
{
enum { bufsize = 1024 };
char buf[bufsize];
int length = snprintf(buf, bufsize,
"X error occurred in GLX probe, error_code=%d, request_code=%d, minor_code=%d\n",
ev->error_code,
ev->request_code,
ev->minor_code);
write(write_end_of_the_pipe, buf, length);
exit(EXIT_FAILURE);
return 0;
}
static void glxtest()
{
///// Open libGL and load needed symbols /////
void *libgl = dlopen("libGL.so.1", RTLD_LAZY);
if (!libgl)
fatal_error("Unable to load libGL.so.1");
typedef GLXFBConfig* (* PFNGLXQUERYEXTENSION) (Display *, int *, int *);
PFNGLXQUERYEXTENSION glXQueryExtension = cast<PFNGLXQUERYEXTENSION>(dlsym(libgl, "glXQueryExtension"));
typedef GLXFBConfig* (* PFNGLXCHOOSEFBCONFIG) (Display *, int, const int *, int *);
PFNGLXCHOOSEFBCONFIG glXChooseFBConfig = cast<PFNGLXCHOOSEFBCONFIG>(dlsym(libgl, "glXChooseFBConfig"));
typedef XVisualInfo* (* PFNGLXGETVISUALFROMFBCONFIG) (Display *, GLXFBConfig);
PFNGLXGETVISUALFROMFBCONFIG glXGetVisualFromFBConfig = cast<PFNGLXGETVISUALFROMFBCONFIG>(dlsym(libgl, "glXGetVisualFromFBConfig"));
typedef GLXPixmap (* PFNGLXCREATEPIXMAP) (Display *, GLXFBConfig, Pixmap, const int *);
PFNGLXCREATEPIXMAP glXCreatePixmap = cast<PFNGLXCREATEPIXMAP>(dlsym(libgl, "glXCreatePixmap"));
typedef GLXContext (* PFNGLXCREATENEWCONTEXT) (Display *, GLXFBConfig, int, GLXContext, Bool);
PFNGLXCREATENEWCONTEXT glXCreateNewContext = cast<PFNGLXCREATENEWCONTEXT>(dlsym(libgl, "glXCreateNewContext"));
typedef Bool (* PFNGLXMAKECURRENT) (Display*, GLXDrawable, GLXContext);
PFNGLXMAKECURRENT glXMakeCurrent = cast<PFNGLXMAKECURRENT>(dlsym(libgl, "glXMakeCurrent"));
typedef void (* PFNGLXDESTROYPIXMAP) (Display *, GLXPixmap);
PFNGLXDESTROYPIXMAP glXDestroyPixmap = cast<PFNGLXDESTROYPIXMAP>(dlsym(libgl, "glXDestroyPixmap"));
typedef void (* PFNGLXDESTROYCONTEXT) (Display*, GLXContext);
PFNGLXDESTROYCONTEXT glXDestroyContext = cast<PFNGLXDESTROYCONTEXT>(dlsym(libgl, "glXDestroyContext"));
typedef GLubyte* (* PFNGLGETSTRING) (GLenum);
PFNGLGETSTRING glGetString = cast<PFNGLGETSTRING>(dlsym(libgl, "glGetString"));
if (!glXQueryExtension ||
!glXChooseFBConfig ||
!glXGetVisualFromFBConfig ||
!glXCreatePixmap ||
!glXCreateNewContext ||
!glXMakeCurrent ||
!glXDestroyPixmap ||
!glXDestroyContext ||
!glGetString)
{
fatal_error("Unable to find required symbols in libGL.so.1");
}
///// Open a connection to the X server /////
Display *dpy = XOpenDisplay(NULL);
if (!dpy)
fatal_error("Unable to open a connection to the X server");
///// Check that the GLX extension is present /////
if (!glXQueryExtension(dpy, NULL, NULL))
fatal_error("GLX extension missing");
XSetErrorHandler(x_error_handler);
///// Get a FBConfig and a visual /////
int attribs[] = {
GLX_DRAWABLE_TYPE, GLX_PIXMAP_BIT,
GLX_X_RENDERABLE, True,
0
};
int numReturned;
GLXFBConfig *fbConfigs = glXChooseFBConfig(dpy, DefaultScreen(dpy), attribs, &numReturned );
if (!fbConfigs)
fatal_error("No FBConfigs found");
XVisualInfo *vInfo = glXGetVisualFromFBConfig(dpy, fbConfigs[0]);
if (!vInfo)
fatal_error("No visual found for first FBConfig");
///// Get a Pixmap and a GLXPixmap /////
Pixmap pixmap = XCreatePixmap(dpy, RootWindow(dpy, vInfo->screen), 4, 4, 32);
GLXPixmap glxpixmap = glXCreatePixmap(dpy, fbConfigs[0], pixmap, NULL);
///// Get a GL context and make it current //////
GLXContext context = glXCreateNewContext(dpy, fbConfigs[0], GLX_RGBA_TYPE, NULL, True);
glXMakeCurrent(dpy, glxpixmap, context);
///// Get GL vendor/renderer/versions strings /////
enum { bufsize = 1024 };
char buf[bufsize];
const GLubyte *vendorString = glGetString(GL_VENDOR);
const GLubyte *rendererString = glGetString(GL_RENDERER);
const GLubyte *versionString = glGetString(GL_VERSION);
if (!vendorString || !rendererString || !versionString)
fatal_error("glGetString returned null");
int length = snprintf(buf, bufsize,
"VENDOR\n%s\nRENDERER\n%s\nVERSION\n%s\n",
vendorString,
rendererString,
versionString);
if (length >= bufsize)
fatal_error("GL strings length too large for buffer size");
///// Check that no X error happened /////
// In case of X errors, our X error handler will exit() now.
// We really want to make sure that the system is able to create a GL context without generating X errors,
// as these would crash the application.
XSync(dpy, False);
///// Finally write data to the pipe /////
write(write_end_of_the_pipe, buf, length);
///// Clean up. Indeed, the parent process might fail to kill us (e.g. if it doesn't need to check GL info)
///// so we might be staying alive for longer than expected, so it's important to consume as little memory as
///// possible. Also we want to check that we're able to do that too without generating X errors.
glXMakeCurrent(dpy, None, NULL); // must release the GL context before destroying it
glXDestroyContext(dpy, context);
glXDestroyPixmap(dpy, glxpixmap);
XFreePixmap(dpy, pixmap);
XCloseDisplay(dpy);
dlclose(libgl);
}
void fire_glxtest_process()
{
int pfd[2];
if (pipe(pfd) == -1) {
perror("pipe");
exit(EXIT_FAILURE);
}
pid_t pid = fork();
if (pid < 0) {
perror("fork");
exit(EXIT_FAILURE);
}
if (pid == 0) {
close(pfd[0]);
write_end_of_the_pipe = pfd[1];
glxtest();
close(pfd[1]);
exit(EXIT_SUCCESS);
}
close(pfd[1]);
mozilla::widget::glxtest_pipe = pfd[0];
mozilla::widget::glxtest_pid = pid;
}