feat(dll): 自 go-hua 迁入 Windows 系统 API 封装

- 互斥体防多开/ShellExecute/窗口类名与标题查询/顶层窗口目录, 新增依赖 lxn/win
- 仅 Windows, 附测试、examples/dll 例程与包 README

dll/mutex.go

@@ -0,0 +1,76 @@
+package dll
+
+import (
+	"fmt"
+	"github.com/lxn/win"
+	"syscall"
+	"unsafe"
+)
+
+// CreateMutex 创建命名互斥体（常用于防止程序多开）
+// bInitialOwner 为是否立即持有；互斥体已存在时返回错误（错误码 183）
+func CreateMutex(bInitialOwner bool, mutexName string) (syscall.Handle, error) {
+
+	// 互斥体名需转为 UTF-16 指针（LPCWSTR），不能直接传 Go string 的地址
+	namePtr, nameErr := syscall.UTF16PtrFromString(mutexName)
+	if nameErr != nil {
+		return 0, nameErr
+	}
+
+	handle, _, err := syscall.SyscallN(procCreateMutexW.Addr(), 0, uintptr(win.BoolToBOOL(bInitialOwner)), uintptr(unsafe.Pointer(namePtr)))
+	if err != 0 {
+		println(err.Error())
+
+		lastError := win.GetLastError()
+		fmt.Println("lastError", lastError)
+		if lastError == 183 {
+			fmt.Println("Mutex 已经存在")
+		}
+
+		return 0, err
+	}
+	//defer syscall.CloseHandle(syscall.Handle(m))
+	if syscall.Handle(handle) != 0 {
+		lastError := win.GetLastError()
+		if lastError == 183 {
+			//fmt.Println("Mutex 已经存在")
+		}
+
+	}
+	// do something with the mutex
+	return syscall.Handle(handle), nil
+}
+
+// MUTANT_ALL_ACCESS 互斥体的完全访问权限
+const MUTANT_ALL_ACCESS = 2031617
+
+// OpenMutex 打开已存在的命名互斥体
+func OpenMutex(bInheritHandle bool, mutexName string) (syscall.Handle, error) {
+	desiredAccess := MUTANT_ALL_ACCESS
+	handle, _, err := syscall.SyscallN(procOpenMutexW.Addr(), uintptr(desiredAccess), uintptr(win.BoolToBOOL(bInheritHandle)), uintptr(unsafe.Pointer(&mutexName)))
+	if err != 0 {
+		return 0, err
+	}
+	defer syscall.CloseHandle(syscall.Handle(handle))
+	if syscall.Handle(handle) == 0 {
+		e2 := win.GetLastError()
+		if e2 == 183 {
+			fmt.Println("打开失败")
+		}
+		fmt.Println(e2)
+
+	} // do something with the mutex
+	fmt.Println("Mutex open", syscall.Handle(handle))
+	return syscall.Handle(handle), nil
+}
+
+// ReleaseMutex 释放互斥体持有权
+func ReleaseMutex(handle syscall.Handle) bool {
+	// 传句柄值本身，而非句柄变量的地址
+	ret, _, e1 := syscall.SyscallN(procReleaseMutex.Addr(), uintptr(handle))
+	if e1 != 0 {
+		println(e1.Error())
+		return false
+	}
+	return ret != 0
+}