glxtest.cpp
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=8 et :
*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//////////////////////////////////////////////////////////////////////////////
//
// 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 <dlfcn.h>
#include "nscore.h"
#include <fcntl.h>
#include "stdint.h"
#ifdef __SUNPRO_CC
#include <stdio.h>
#endif
#include "X11/Xlib.h"
#include "X11/Xutil.h"
// stuff from glx.h
typedef struct __GLXcontextRec *GLXContext;
typedef XID GLXPixmap;
typedef XID GLXDrawable;
/* GLX 1.3 and later */
typedef struct __GLXFBConfigRec *GLXFBConfig;
typedef XID GLXFBConfigID;
typedef XID GLXContextID;
typedef XID GLXWindow;
typedef XID GLXPbuffer;
#define GLX_RGBA 4
#define GLX_RED_SIZE 8
#define GLX_GREEN_SIZE 9
#define GLX_BLUE_SIZE 10
// stuff from gl.h
typedef uint8_t GLubyte;
typedef uint32_t GLenum;
#define GL_VENDOR 0x1F00
#define GL_RENDERER 0x1F01
#define GL_VERSION 0x1F02
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()
{
// we want to redirect to /dev/null stdout, stderr, and while we're at it,
// any PR logging file descriptors. To that effect, we redirect all positive
// file descriptors up to what open() returns here. In particular, 1 is stdout and 2 is stderr.
int fd = open("/dev/null", O_WRONLY);
for (int i = 1; i < fd; i++)
dup2(fd, i);
close(fd);
if (getenv("MOZ_AVOID_OPENGL_ALTOGETHER"))
fatal_error("The MOZ_AVOID_OPENGL_ALTOGETHER environment variable is defined");
///// Open libGL and load needed symbols /////
#ifdef __OpenBSD__
#define LIBGL_FILENAME "libGL.so"
#else
#define LIBGL_FILENAME "libGL.so.1"
#endif
void *libgl = dlopen(LIBGL_FILENAME, RTLD_LAZY);
if (!libgl)
fatal_error("Unable to load " LIBGL_FILENAME);
typedef void* (* PFNGLXGETPROCADDRESS) (const char *);
PFNGLXGETPROCADDRESS glXGetProcAddress = cast<PFNGLXGETPROCADDRESS>(dlsym(libgl, "glXGetProcAddress"));
if (!glXGetProcAddress)
fatal_error("Unable to find glXGetProcAddress in " LIBGL_FILENAME);
typedef GLXFBConfig* (* PFNGLXQUERYEXTENSION) (Display *, int *, int *);
PFNGLXQUERYEXTENSION glXQueryExtension = cast<PFNGLXQUERYEXTENSION>(glXGetProcAddress("glXQueryExtension"));
typedef GLXFBConfig* (* PFNGLXQUERYVERSION) (Display *, int *, int *);
PFNGLXQUERYVERSION glXQueryVersion = cast<PFNGLXQUERYVERSION>(dlsym(libgl, "glXQueryVersion"));
typedef XVisualInfo* (* PFNGLXCHOOSEVISUAL) (Display *, int, int *);
PFNGLXCHOOSEVISUAL glXChooseVisual = cast<PFNGLXCHOOSEVISUAL>(glXGetProcAddress("glXChooseVisual"));
typedef GLXContext (* PFNGLXCREATECONTEXT) (Display *, XVisualInfo *, GLXContext, Bool);
PFNGLXCREATECONTEXT glXCreateContext = cast<PFNGLXCREATECONTEXT>(glXGetProcAddress("glXCreateContext"));
typedef Bool (* PFNGLXMAKECURRENT) (Display*, GLXDrawable, GLXContext);
PFNGLXMAKECURRENT glXMakeCurrent = cast<PFNGLXMAKECURRENT>(glXGetProcAddress("glXMakeCurrent"));
typedef void (* PFNGLXDESTROYCONTEXT) (Display*, GLXContext);
PFNGLXDESTROYCONTEXT glXDestroyContext = cast<PFNGLXDESTROYCONTEXT>(glXGetProcAddress("glXDestroyContext"));
typedef GLubyte* (* PFNGLGETSTRING) (GLenum);
PFNGLGETSTRING glGetString = cast<PFNGLGETSTRING>(glXGetProcAddress("glGetString"));
if (!glXQueryExtension ||
!glXQueryVersion ||
!glXChooseVisual ||
!glXCreateContext ||
!glXMakeCurrent ||
!glXDestroyContext ||
!glGetString)
{
fatal_error("glXGetProcAddress couldn't find required functions");
}
///// Open a connection to the X server /////
Display *dpy = XOpenDisplay(nullptr);
if (!dpy)
fatal_error("Unable to open a connection to the X server");
///// Check that the GLX extension is present /////
if (!glXQueryExtension(dpy, nullptr, nullptr))
fatal_error("GLX extension missing");
XSetErrorHandler(x_error_handler);
///// Get a visual /////
int attribs[] = {
GLX_RGBA,
GLX_RED_SIZE, 1,
GLX_GREEN_SIZE, 1,
GLX_BLUE_SIZE, 1,
None };
XVisualInfo *vInfo = glXChooseVisual(dpy, DefaultScreen(dpy), attribs);
if (!vInfo)
fatal_error("No visuals found");
// using a X11 Window instead of a GLXPixmap does not crash
// fglrx in indirect rendering. bug 680644
Window window;
XSetWindowAttributes swa;
swa.colormap = XCreateColormap(dpy, RootWindow(dpy, vInfo->screen),
vInfo->visual, AllocNone);
swa.border_pixel = 0;
window = XCreateWindow(dpy, RootWindow(dpy, vInfo->screen),
0, 0, 16, 16,
0, vInfo->depth, InputOutput, vInfo->visual,
CWBorderPixel | CWColormap, &swa);
///// Get a GL context and make it current //////
GLXContext context = glXCreateContext(dpy, vInfo, nullptr, True);
glXMakeCurrent(dpy, window, context);
///// Look for this symbol to determine texture_from_pixmap support /////
void* glXBindTexImageEXT = glXGetProcAddress("glXBindTexImageEXT");
///// 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\nTFP\n%s\n",
vendorString,
rendererString,
versionString,
glXBindTexImageEXT ? "TRUE" : "FALSE");
if (length >= bufsize)
fatal_error("GL strings length too large for buffer size");
///// 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, nullptr); // must release the GL context before destroying it
glXDestroyContext(dpy, context);
XDestroyWindow(dpy, window);
XFreeColormap(dpy, swa.colormap);
XCloseDisplay(dpy);
dlclose(libgl);
///// Finally write data to the pipe
write(write_end_of_the_pipe, buf, length);
}
/** \returns true in the child glxtest process, false in the parent process */
bool fire_glxtest_process()
{
int pfd[2];
if (pipe(pfd) == -1) {
perror("pipe");
return false;
}
pid_t pid = fork();
if (pid < 0) {
perror("fork");
close(pfd[0]);
close(pfd[1]);
return false;
}
if (pid == 0) {
close(pfd[0]);
write_end_of_the_pipe = pfd[1];
glxtest();
close(pfd[1]);
return true;
}
close(pfd[1]);
mozilla::widget::glxtest_pipe = pfd[0];
mozilla::widget::glxtest_pid = pid;
return false;
}
