14.

main_instance_unix.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 )
 
@@ -15,6 +16,17 @@ 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)
 
+// secondInstanceCommand receives commands from a spawned second process (e.g. desktop shortcut).
+// Commands are 1-byte values written to the unix socket.
+var secondInstanceCommand = make(chan byte, 16)
+
+const (
+	instanceCmdShow   byte = 1
+	instanceCmdStart  byte = 2
+	instanceCmdStop   byte = 3
+	instanceCmdToggle byte = 4
+)
+
 func instanceSocketPath() (string, error) {
 	home, err := os.UserHomeDir()
 	if err != nil {
@@ -23,17 +35,40 @@ func instanceSocketPath() (string, error) {
 	return filepath.Join(home, configDir, instanceSockName), nil
 }
 
-func tryNotifyRunningInstanceToShow() {
+func tryNotifyRunningInstance(cmd byte) bool {
 	path, err := instanceSocketPath()
 	if err != nil {
-		return
+		return false
 	}
 	c, err := net.DialTimeout("unix", path, 500*time.Millisecond)
 	if err != nil {
-		return
+		return false
 	}
 	defer c.Close()
-	_, _ = c.Write([]byte{1})
+	if cmd == 0 {
+		cmd = instanceCmdShow
+	}
+	_, _ = c.Write([]byte{cmd})
+	return true
+}
+
+func tryNotifyRunningInstanceToShow() bool {
+	return tryNotifyRunningInstance(instanceCmdShow)
+}
+
+func tryNotifyRunningInstanceAction(action string) bool {
+	switch strings.ToLower(strings.TrimSpace(action)) {
+	case "show":
+		return tryNotifyRunningInstance(instanceCmdShow)
+	case "start":
+		return tryNotifyRunningInstance(instanceCmdStart)
+	case "stop":
+		return tryNotifyRunningInstance(instanceCmdStop)
+	case "toggle":
+		return tryNotifyRunningInstance(instanceCmdToggle)
+	default:
+		return false
+	}
 }
 
 func runSecondInstanceListener() {
@@ -54,6 +89,20 @@ func runSecondInstanceListener() {
 			}
 			go func(conn net.Conn) {
 				defer conn.Close()
+				buf := make([]byte, 1)
+				n, _ := conn.Read(buf)
+				if n == 1 {
+					select {
+					case secondInstanceCommand <- buf[0]:
+					default:
+					}
+				} else {
+					// Backwards-compatible: any connection with no payload = show window.
+					select {
+					case secondInstanceCommand <- instanceCmdShow:
+					default:
+					}
+				}
 				_, _ = io.Copy(io.Discard, conn)
 				select {
 				case secondInstanceWake <- struct{}{}: