cmd/robloxmutexer: refactor; wait for roblox to die

cmd/robloxmutexer/main.go

@@ -0,0 +1,83 @@
+//go:build windows
+// +build windows
+
+package main
+
+import (
+	"log"
+	"unsafe"
+	"time"
+
+	"golang.org/x/sys/windows"
+)
+
+func main() {
+	log.SetPrefix("robloxmutexer: ")
+	log.SetFlags(log.Lmsgprefix | log.LstdFlags)
+
+	if err := lock(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func lock() error {
+	name, err := windows.UTF16PtrFromString("ROBLOX_singletonMutex")
+	if err != nil {
+		return err
+	}
+
+	mutex, err := windows.CreateMutex(nil, false, name)
+	if err != nil {
+		return err
+	}
+	defer windows.CloseHandle(mutex)
+
+	_, err = windows.WaitForSingleObject(mutex, 0)
+	if err != nil {
+		return err
+	}
+
+	log.Println("Singleton mutex locked, waiting for no roblox processes")
+
+	for {
+		time.Sleep(5 * time.Second)
+		r, err := robloxRunning()
+		if err != nil {
+			return err
+		}
+
+		if !r {
+			log.Println("No roblox processes found, freeing mutex")
+			break
+		}
+	}
+
+	return nil
+}
+
+func robloxRunning() (bool, error) {
+	snap, err := windows.CreateToolhelp32Snapshot(windows.TH32CS_SNAPPROCESS, 0)
+	if err != nil {
+		return false, err
+	}
+	defer windows.CloseHandle(snap)
+
+	pe := windows.ProcessEntry32{
+		Size: (uint32)(unsafe.Sizeof(windows.ProcessEntry32{})),
+	}
+
+	for {
+		if err := windows.Process32Next(snap, &pe); err != nil {
+			// Reached end
+			if err == windows.ERROR_NO_MORE_FILES {
+				break
+			}
+			return false, err
+		}
+		if windows.UTF16ToString(pe.ExeFile[:]) == "RobloxPlayerBeta" {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}