CreateMutex为什么失败？

[asuror]

g_hSingleton = CreateMutex(NULL, FALSE, "MyNamespace\\Sigleton");调用失败，谁知道是什么原因？

[liuzxchina]

windows核心编程里面有讲到怎样使用名字空间，代码如下，你看看具体问题在哪里。

void CheckInstances() {

   // Create the boundary descriptor
   g_hBoundary = CreateBoundaryDescriptor(g_szBoundary, 0);

   // Create a SID corresponding to the Local Administrator group
   BYTE localAdminSID[SECURITY_MAX_SID_SIZE];
   PSID pLocalAdminSID = &localAdminSID;
   DWORD cbSID = sizeof(localAdminSID);
   if (!CreateWellKnownSid(
      WinBuiltinAdministratorsSid, NULL, pLocalAdminSID, &cbSID)
      ) {
      AddText(TEXT("AddSIDToBoundaryDescriptor failed: %u\r\n"), 
         GetLastError());
      return;
   }
   
   // Associate the Local Admin SID to the boundary descriptor
   // --> only applications running under an administrator user
   //     will be able to access the kernel objects in the same namespace
   if (!AddSIDToBoundaryDescriptor(&g_hBoundary, pLocalAdminSID)) {
      AddText(TEXT("AddSIDToBoundaryDescriptor failed: %u\r\n"), 
         GetLastError());
      return;
   }

   // Create the namespace for Local Administrators only
   SECURITY_ATTRIBUTES sa;
   sa.nLength = sizeof(sa);
   sa.bInheritHandle = FALSE;
   if (!ConvertStringSecurityDescriptorToSecurityDescriptor(
      TEXT("D:(A;;GA;;;BA)"), 
      SDDL_REVISION_1, &sa.lpSecurityDescriptor, NULL)) {
      AddText(TEXT("Security Descriptor creation failed: %u\r\n"), GetLastError());
      return;
   }

   g_hNamespace = 
      CreatePrivateNamespace(&sa, g_hBoundary, g_szNamespace);

   // Don't forget to release memory for the security descriptor
   LocalFree(sa.lpSecurityDescriptor);


   // Check the private namespace creation result
   DWORD dwLastError = GetLastError();
   if (g_hNamespace == NULL) {
      // Nothing to do if access is denied
      // --> this code must run under a Local Administrator account
      if (dwLastError == ERROR_ACCESS_DENIED) {
         AddText(TEXT("Access denied when creating the namespace.\r\n"));
         AddText(TEXT("   You must be running as Administrator.\r\n\r\n"));
         return;
      } else { 
         if (dwLastError == ERROR_ALREADY_EXISTS) {
         // If another instance has already created the namespace, 
         // we need to open it instead. 
            AddText(TEXT("CreatePrivateNamespace failed: %u\r\n"), dwLastError);
            g_hNamespace = OpenPrivateNamespace(g_hBoundary, g_szNamespace);
            if (g_hNamespace == NULL) {
               AddText(TEXT("   and OpenPrivateNamespace failed: %u\r\n"), 
               dwLastError);
               return;
            } else {
               g_bNamespaceOpened = TRUE;
               AddText(TEXT("   but OpenPrivateNamespace succeeded\r\n\r\n"));
            }
         } else {
            AddText(TEXT("Unexpected error occured: %u\r\n\r\n"),
               dwLastError);
            return;
         }
      }
   }
   
   // Try to create the mutex object with a name 
   // based on the private namespace 
   TCHAR szMutexName[64];
   StringCchPrintf(szMutexName, _countof(szMutexName), TEXT("%s\\%s"), 
      g_szNamespace, TEXT("Singleton"));

   g_hSingleton = CreateMutex(NULL, FALSE, szMutexName);
   if (GetLastError() == ERROR_ALREADY_EXISTS) {
      // There is already an instance of this Singleton object
      AddText(TEXT("Another instance of Singleton is running:\r\n"));
      AddText(TEXT("--> Impossible to access application features.\r\n"));
   } else  {
      // First time the Singleton object is created
      AddText(TEXT("First instance of Singleton:\r\n"));
      AddText(TEXT("--> Access application features now.\r\n"));
   }
}