From: Jan Grulich <jgrulich@redhat.com>
Date: Fri, 10 Mar 2023 09:21:00 +0000
Subject: Bug 1819035 - get EGL display based on the used platform in the
 browser r=webrtc-reviewers,ng

Because of a possible misconfiguration or a possible driver issue it
might happen that the browser will use a different driver on X11 and
end up using yet another one for wayland/gbm, which might lead to not
working screen sharing in the better case, but also to a crash in the
other driver (Nvidia). This adds a check for platform the browser runs
on, if it's XWayland or Wayland and based on that query EGL display for
that specific platform, rather than going for the Wayland one only.

Differential Revision: https://phabricator.services.mozilla.com/D171858
Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/c8606497de1f461a6352456e0e511c2ae498d526
---
 .../linux/wayland/egl_dmabuf.cc               | 30 +++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/modules/desktop_capture/linux/wayland/egl_dmabuf.cc b/modules/desktop_capture/linux/wayland/egl_dmabuf.cc
index 5bbd5d7aba..80da597e29 100644
--- a/modules/desktop_capture/linux/wayland/egl_dmabuf.cc
+++ b/modules/desktop_capture/linux/wayland/egl_dmabuf.cc
@@ -13,6 +13,7 @@
 #include <asm/ioctl.h>
 #include <dlfcn.h>
 #include <fcntl.h>
+#include <gdk/gdk.h>
 #include <libdrm/drm_fourcc.h>
 #include <linux/types.h>
 #include <spa/param/video/format-utils.h>
@@ -200,6 +201,26 @@ static void CloseLibrary(void* library) {
   }
 }
 
+static bool IsWaylandDisplay() {
+  static auto sGdkWaylandDisplayGetType =
+    (GType (*)(void))dlsym(RTLD_DEFAULT, "gdk_wayland_display_get_type");
+  if (!sGdkWaylandDisplayGetType) {
+    return false;
+  }
+  return (G_TYPE_CHECK_INSTANCE_TYPE ((gdk_display_get_default()),
+                                      sGdkWaylandDisplayGetType()));
+}
+
+static bool IsX11Display() {
+  static auto sGdkX11DisplayGetType =
+    (GType (*)(void))dlsym(RTLD_DEFAULT, "gdk_x11_display_get_type");
+  if (!sGdkX11DisplayGetType) {
+    return false;
+  }
+  return (G_TYPE_CHECK_INSTANCE_TYPE ((gdk_display_get_default()),
+                                      sGdkX11DisplayGetType()));
+}
+
 static void* g_lib_egl = nullptr;
 
 RTC_NO_SANITIZE("cfi-icall")
@@ -331,8 +352,13 @@ EglDmaBuf::EglDmaBuf() {
     return;
   }
 
-  egl_.display = EglGetPlatformDisplay(EGL_PLATFORM_WAYLAND_KHR,
-                                       (void*)EGL_DEFAULT_DISPLAY, nullptr);
+  if (IsWaylandDisplay()) {
+    egl_.display = EglGetPlatformDisplay(EGL_PLATFORM_WAYLAND_KHR,
+                                         (void*)EGL_DEFAULT_DISPLAY, nullptr);
+  } else if (IsX11Display()) {
+    egl_.display = EglGetPlatformDisplay(EGL_PLATFORM_X11_KHR,
+                                         (void*)EGL_DEFAULT_DISPLAY, nullptr);
+  }
 
   if (egl_.display == EGL_NO_DISPLAY) {
     RTC_LOG(LS_ERROR) << "Failed to obtain default EGL display: "
-- 
2.34.1