From 5da6f9fb0a25e55c302268f0d524189bffd53e21 Mon Sep 17 00:00:00 2001
From: Terrence Ezrol <terry@ezrol.com>
Date: Sun, 3 Aug 2025 11:28:37 -0400
Subject: [PATCH] Some wayland issues

At least with experimental cinnamon w/ xwayland there is a minor bug:

DISPLAY may be set to :1, despite xwayland listening on :0
in this case connections to :1 will indicate not ready/retry

in this case to mimic most X11 libraries try :0 if we get this on :1, or :1 if we are on :0
otherwise we will retry the current DISPLAY requested

to be sure this is a valid approch we also check `xset q` this must return as working with the original display to try the other one
---
 main.go           | 23 +++++++++++++++++++++++
 x11probe/probe.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/main.go b/main.go
index 59020fa..94f1003 100644
--- a/main.go
+++ b/main.go
@@ -52,7 +52,30 @@ func main() {
 		log.Fatalf("Connection probe error: %v", err)
 	}
 
+	if status == x11probe.X11TemporarilyUnavailable {
+		//retry 1x, but change display if :0/:1 assuming wayland dead socket
+		if display == ":1" && x11probe.CheckDisplay(display) {
+			log.Printf("is wayland scoket wrong? try :0")
+			display = ":0"
+			connType, target = resolveDisplay(display)
+			fmt.Printf("Proxying to %s (%s)\n", target, connTypeString(connType))
+		} else {
+			if display == ":0" && x11probe.CheckDisplay(display) {
+				log.Printf("is wayland scoket wrong? try :1")
+				display = ":1"
+				connType, target = resolveDisplay(display)
+				fmt.Printf("Proxying to %s (%s)\n", target, connTypeString(connType))
+			}
+		}
+		status, err = x11probe.ProbeX11Socket(connType, target, timeout)
+		if err != nil {
+			log.Fatalf("Connection probe error: %v", err)
+		}
+	}
+
 	switch status {
+	case x11probe.X11TemporarilyUnavailable:
+		log.Fatalf("Target connection is temporarily unavalible, is X11 running?")
 	case x11probe.X11Live:
 		log.Println("X11 socket is live and accepting connections")
 	case x11probe.X11AuthRequired:
diff --git a/x11probe/probe.go b/x11probe/probe.go
index 4d593bf..a9de38d 100644
--- a/x11probe/probe.go
+++ b/x11probe/probe.go
@@ -1,11 +1,15 @@
 package x11probe
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"log"
 	"net"
+	"os"
+	"os/exec"
 	"strings"
+	"syscall"
 	"time"
 )
 
@@ -23,6 +27,7 @@ const (
 	X11Dead X11Status = iota
 	X11Live
 	X11AuthRequired
+	X11TemporarilyUnavailable
 )
 
 func ProbeX11Socket(connType ConnType, target string, timeout time.Duration) (X11Status, error) {
@@ -35,12 +40,18 @@ func ProbeX11Socket(connType ConnType, target string, timeout time.Duration) (X1
 	case Unix:
 		conn, err = net.DialTimeout("unix", target, timeout)
 		if err != nil {
+			if isResourceTemporarilyUnavailable(err) { // Check for specific error
+				return X11TemporarilyUnavailable, nil
+			}
 			return X11Dead, fmt.Errorf("unix dial failed: %w", err)
 		}
 	case TCP:
 		addr := parseTCPAddress(target)
 		conn, err = net.DialTimeout("tcp", addr, timeout)
 		if err != nil {
+			if isResourceTemporarilyUnavailable(err) { // Check for specific error
+				return X11TemporarilyUnavailable, nil
+			}
 			return X11Dead, fmt.Errorf("TCP dial failed: %w", err)
 		}
 	}
@@ -60,6 +71,18 @@ func ProbeX11Socket(connType ConnType, target string, timeout time.Duration) (X1
 	return status, nil
 }
 
+func isResourceTemporarilyUnavailable(err error) bool {
+	// Match exact error string first
+	if strings.Contains(err.Error(), "resource temporarily unavailable") {
+		return true
+	}
+	// Fallback to syscall-level check
+	if errors.Is(err, syscall.EAGAIN) {
+		return true
+	}
+	return false
+}
+
 func parseTCPAddress(target string) string {
 	parts := strings.SplitN(target, ":", 2)
 
@@ -123,3 +146,15 @@ func readResponse(conn net.Conn, timeout time.Duration) (X11Status, error) {
 	}
 
 }
+
+func CheckDisplay(display string) bool {
+	cmd := exec.Command("xset", "q")
+	cmd.Env = append(os.Environ(), fmt.Sprintf("DISPLAY=%s", display))
+
+	if err := cmd.Run(); err != nil {
+		fmt.Fprintf(os.Stderr, "xset q failed for DISPLAY=%s: %v\n", display, err)
+		return false
+	}
+
+	return true
+}