Initial commit with project setup and basic structure established.

lib/instance/mutex.go

@@ -0,0 +1,37 @@
+package instance
+
+import (
+	"errors"
+
+	"golang.org/x/sys/windows"
+
+	"tea.chunkbyte.com/kato/go-worm/lib/config"
+)
+
+type Guard struct {
+	handle windows.Handle
+}
+
+func Acquire() (*Guard, error) {
+	name, err := windows.UTF16PtrFromString(config.MutexName)
+	if err != nil {
+		return nil, err
+	}
+	h, err := windows.CreateMutex(nil, false, name)
+	if h == 0 {
+		return nil, err
+	}
+	if errors.Is(err, windows.ERROR_ALREADY_EXISTS) {
+		windows.CloseHandle(h)
+		return nil, errors.New("agent already running")
+	}
+	return &Guard{handle: h}, nil
+}
+
+func (g *Guard) Close() {
+	if g == nil || g.handle == 0 {
+		return
+	}
+	windows.CloseHandle(g.handle)
+	g.handle = 0
+}