/* -*- 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"

#include "mozilla/Unused.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

// GLX_MESA_query_renderer
#define GLX_RENDERER_VENDOR_ID_MESA                            0x8183
#define GLX_RENDERER_DEVICE_ID_MESA                            0x8184
#define GLX_RENDERER_VERSION_MESA                              0x8185
#define GLX_RENDERER_ACCELERATED_MESA                          0x8186
#define GLX_RENDERER_VIDEO_MEMORY_MESA                         0x8187
#define GLX_RENDERER_UNIFIED_MEMORY_ARCHITECTURE_MESA          0x8188
#define GLX_RENDERER_PREFERRED_PROFILE_MESA                    0x8189
#define GLX_RENDERER_OPENGL_CORE_PROFILE_VERSION_MESA          0x818A
#define GLX_RENDERER_OPENGL_COMPATIBILITY_PROFILE_VERSION_MESA 0x818B
#define GLX_RENDERER_OPENGL_ES_PROFILE_VERSION_MESA            0x818C
#define GLX_RENDERER_OPENGL_ES2_PROFILE_VERSION_MESA           0x818D
#define GLX_RENDERER_ID_MESA                                   0x818E

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;
}  // namespace widget
}  // namespace mozilla

// 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) {
  mozilla::Unused << write(write_end_of_the_pipe, str, strlen(str));
  mozilla::Unused << 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);
  mozilla::Unused << write(write_end_of_the_pipe, buf, length);
  _exit(EXIT_FAILURE);
  return 0;
}

// glxtest is declared inside extern "C" so that the name is not mangled.
// The name is used in build/valgrind/x86_64-pc-linux-gnu.sup to suppress
// memory leak errors because we run it inside a short lived fork and we don't
// care about leaking memory
extern "C" {

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 = 2048 };
  char buf[bufsize];
  const GLubyte* versionString = glGetString(GL_VERSION);
  const GLubyte* vendorString = glGetString(GL_VENDOR);
  const GLubyte* rendererString = glGetString(GL_RENDERER);

  if (!versionString || !vendorString || !rendererString)
    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");

  // If GLX_MESA_query_renderer is available, populate additional data.
  typedef Bool (*PFNGLXQUERYCURRENTRENDERERINTEGERMESAPROC) (int attribute, unsigned int* value);
  PFNGLXQUERYCURRENTRENDERERINTEGERMESAPROC glXQueryCurrentRendererIntegerMESAProc =
    cast<PFNGLXQUERYCURRENTRENDERERINTEGERMESAPROC>(glXGetProcAddress("glXQueryCurrentRendererIntegerMESA"));
  if (glXQueryCurrentRendererIntegerMESAProc) {
    unsigned int vendorId, deviceId, accelerated, videoMemoryMB;
    glXQueryCurrentRendererIntegerMESAProc(GLX_RENDERER_VENDOR_ID_MESA, &vendorId);
    glXQueryCurrentRendererIntegerMESAProc(GLX_RENDERER_DEVICE_ID_MESA, &deviceId);
    glXQueryCurrentRendererIntegerMESAProc(GLX_RENDERER_ACCELERATED_MESA, &accelerated);
    glXQueryCurrentRendererIntegerMESAProc(GLX_RENDERER_VIDEO_MEMORY_MESA, &videoMemoryMB);

    // Truncate IDs to 4 digits- that's all PCI IDs are.
    vendorId &= 0xFFFF;
    deviceId &= 0xFFFF;

    length += snprintf(buf + length, bufsize,
                       "MESA_VENDOR_ID\n0x%04x\n"
                       "MESA_DEVICE_ID\n0x%04x\n"
                       "MESA_ACCELERATED\n%s\n"
                       "MESA_VRAM\n%dMB\n",
                       vendorId, deviceId, accelerated ? "TRUE" : "FALSE",
                       videoMemoryMB);

    if (length >= bufsize)
      fatal_error("GL strings length too large for buffer size");
  }

  // From Mesa's GL/internal/dri_interface.h, to be used by DRI clients.
  typedef const char * (* PFNGLXGETSCREENDRIVERPROC) (Display *dpy, int scrNum);
  PFNGLXGETSCREENDRIVERPROC glXGetScreenDriverProc =
    cast<PFNGLXGETSCREENDRIVERPROC>(glXGetProcAddress("glXGetScreenDriver"));
  if (glXGetScreenDriverProc) {
    const char* driDriver = glXGetScreenDriverProc(dpy, DefaultScreen(dpy));
    if (driDriver) {
      length += snprintf(buf + length, bufsize, "DRI_DRIVER\n%s\n", driDriver);
      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);

#ifdef NS_FREE_PERMANENT_DATA  // conditionally defined in nscore.h, don't
                               // forget to #include it above
  XCloseDisplay(dpy);
#else
  // This XSync call wanted to be instead:
  //   XCloseDisplay(dpy);
  // but this can cause 1-minute stalls on certain setups using Nouveau, see bug
  // 973192
  XSync(dpy, False);
#endif

  dlclose(libgl);

  ///// Finally write data to the pipe
  mozilla::Unused << 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;
  }
  // The child exits early to avoid running the full shutdown sequence and avoid
  // conflicting with threads we have already spawned (like the profiler).
  if (pid == 0) {
    close(pfd[0]);
    write_end_of_the_pipe = pfd[1];
    glxtest();
    close(pfd[1]);
    _exit(0);
  }

  close(pfd[1]);
  mozilla::widget::glxtest_pipe = pfd[0];
  mozilla::widget::glxtest_pid = pid;
  return false;
}