- there can be only one instance of the device manager

svn path=/trunk/; revision=28905

reactos/base/applications/mscutils/devmgmt/devmgmt.c

@@ -11,6 +11,7 @@
 
 HINSTANCE hInstance;
 HANDLE ProcessHeap;
+HANDLE hMutex;
 
 int WINAPI
 _tWinMain(HINSTANCE hThisInstance,
@@ -24,6 +25,18 @@ _tWinMain(HINSTANCE hThisInstance,
     int Ret = 1;
     INITCOMMONCONTROLSEX icex;
 
+    hMutex = CreateMutex(NULL, TRUE, _T("devmgmt_mutex"));
+    if (hMutex == NULL || GetLastError() == ERROR_ALREADY_EXISTS)
+    {
+        if (hMutex)
+        {
+            CloseHandle(hMutex);
+        }
+        return 0;
+    }
+
+
+
     hInstance = hThisInstance;
     ProcessHeap = GetProcessHeap();
 
@@ -59,7 +72,7 @@ _tWinMain(HINSTANCE hThisInstance,
     }
 
     LocalFree((HLOCAL)lpAppName);
-
+    CloseHandle(hMutex);
     return Ret;
 }