File sddm-relaxed-auth.patch of Package sddm

From: Fabian Vogt <fabian@ritter-vogt.de>
Subject: Set XAUTHLOCALHOSTNAME to allow hostname changes

Our libxcb is patched to retry with $XAUTHLOCALHOSTNAME as hostname if the
Xauthority entry for the current hostname does not work.
There's a stale PR to do something similar (FamilyWild using libXau) upstream:
https://github.com/sddm/sddm/pull/863
FamilyWild is not a complete solution either, only when using a temporary
Xauthority file for each session separately.

Index: sddm-0.18.0/src/helper/Backend.cpp
===================================================================
--- sddm-0.18.0.orig/src/helper/Backend.cpp
+++ sddm-0.18.0/src/helper/Backend.cpp
@@ -27,6 +27,7 @@
 #include "UserSession.h"
 
 #include <QtCore/QProcessEnvironment>
+#include <QtNetwork/QHostInfo>
 
 #include <pwd.h>
 
@@ -69,6 +70,7 @@ namespace SDDM {
                         .arg(QString::fromLocal8Bit(pw->pw_dir))
                         .arg(mainConfig.X11.UserAuthFile.get());
                 env.insert(QStringLiteral("XAUTHORITY"), value);
+                env.insert(QStringLiteral("XAUTHLOCALHOSTNAME"), QHostInfo::localHostName());
             }
             // TODO: I'm fairly sure this shouldn't be done for PAM sessions, investigate!
             m_app->session()->setProcessEnvironment(env);
Index: sddm-0.18.0/src/daemon/Display.cpp
===================================================================
--- sddm-0.18.0.orig/src/daemon/Display.cpp
+++ sddm-0.18.0/src/daemon/Display.cpp
@@ -316,8 +316,10 @@ namespace SDDM {
 
         QProcessEnvironment env;
         env.insert(QStringLiteral("PATH"), mainConfig.Users.DefaultPath.get());
-        if (session.xdgSessionType() == QLatin1String("x11"))
+        if (session.xdgSessionType() == QLatin1String("x11")) {
             env.insert(QStringLiteral("DISPLAY"), name());
+            env.insert(QStringLiteral("XAUTHLOCALHOSTNAME"), daemonApp->hostName());
+        }
         env.insert(QStringLiteral("XDG_SEAT_PATH"), daemonApp->displayManager()->seatPath(seat()->name()));
         env.insert(QStringLiteral("XDG_SESSION_PATH"), daemonApp->displayManager()->sessionPath(QStringLiteral("Session%1").arg(daemonApp->newSessionId())));
         env.insert(QStringLiteral("DESKTOP_SESSION"), session.desktopSession());
Index: sddm-0.18.0/src/daemon/Greeter.cpp
===================================================================
--- sddm-0.18.0.orig/src/daemon/Greeter.cpp
+++ sddm-0.18.0/src/daemon/Greeter.cpp
@@ -114,6 +114,7 @@ namespace SDDM {
             // set process environment
             QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
             env.insert(QStringLiteral("DISPLAY"), m_display->name());
+            env.insert(QStringLiteral("XAUTHLOCALHOSTNAME"), daemonApp->hostName());
             env.insert(QStringLiteral("XAUTHORITY"), m_authPath);
             env.insert(QStringLiteral("XCURSOR_THEME"), xcursorTheme);
             env.insert(QStringLiteral("QT_IM_MODULE"), mainConfig.InputMethod.get());
@@ -175,6 +176,7 @@ namespace SDDM {
             env.insert(QStringLiteral("PATH"), mainConfig.Users.DefaultPath.get());
             env.insert(QStringLiteral("DISPLAY"), m_display->name());
             env.insert(QStringLiteral("XAUTHORITY"), m_authPath);
+            env.insert(QStringLiteral("XAUTHLOCALHOSTNAME"), daemonApp->hostName());
             env.insert(QStringLiteral("XCURSOR_THEME"), xcursorTheme);
             env.insert(QStringLiteral("XDG_SEAT"), m_display->seat()->name());
             env.insert(QStringLiteral("XDG_SEAT_PATH"), daemonApp->displayManager()->seatPath(m_display->seat()->name()));