2

main_instance_unix.go

@@ -0,0 +1,65 @@
+//go:build unix && !windows
+
+package main
+
+import (
+	"io"
+	"net"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+const instanceSockName = "instance.sock"
+
+// secondInstanceWake is closed when a second process asks the running app to show its window.
+var secondInstanceWake = make(chan struct{}, 8)
+
+func instanceSocketPath() (string, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(home, configDir, instanceSockName), nil
+}
+
+func tryNotifyRunningInstanceToShow() {
+	path, err := instanceSocketPath()
+	if err != nil {
+		return
+	}
+	c, err := net.DialTimeout("unix", path, 500*time.Millisecond)
+	if err != nil {
+		return
+	}
+	defer c.Close()
+	_, _ = c.Write([]byte{1})
+}
+
+func runSecondInstanceListener() {
+	path, err := instanceSocketPath()
+	if err != nil {
+		return
+	}
+	_ = os.Remove(path)
+	l, err := net.Listen("unix", path)
+	if err != nil {
+		return
+	}
+	go func() {
+		for {
+			c, err := l.Accept()
+			if err != nil {
+				return
+			}
+			go func(conn net.Conn) {
+				defer conn.Close()
+				_, _ = io.Copy(io.Discard, conn)
+				select {
+				case secondInstanceWake <- struct{}{}:
+				default:
+				}
+			}(c)
+		}
+	}()
+}