Determine if only one instance is running: Difference between revisions

=={{header|TXR}}==

==== Microsoft Windows ====

<lang txrlisp>;;; Define some typedefs for clear correspondence with Win32

(typedef HANDLE cptr)

(typedef LPSECURITY_ATTRIBUTES cptr)

(typedef WINERR (enum WINERR ERROR_SUCCESS

(ERROR_ALREADY_EXISTS 183)))

(typedef BOOL (enum BOOL FALSE TRUE))

(typedef LPCWSTR wstr)

;;; More familiar spelling for null pointer.

(defvarl NULL cptr-null)

;;; Define access to foreign functions.

(with-dyn-lib "kernel32.dll"

(deffi CreateMutex "CreateMutexW" HANDLE (LPSECURITY_ATTRIBUTES BOOL LPCWSTR))

(deffi CloseHandle "CloseHandle" BOOL (HANDLE))

(deffi GetLastError "GetLastError" WINERR ()))

;;; Now, the single-instance program:

(defvar m (CreateMutex NULL 'TRUE "ApplicationName"))

(unless (eq (GetLastError) 'ERROR_ALREADY_EXISTS)

;; mutual exclusion here

)

(CloseHandle m)