Check if MacBook LID closed.m

bool isLidClosed(void)
{
  bool isClosed = false;
  io_registry_entry_t     rootDomain;
  mach_port_t             masterPort;
  CFTypeRef               clamShellStateRef = NULL;
  
  // Retrieve the IOKit's master port so a notification port can be created
  IOReturn ioReturn = IOMasterPort(MACH_PORT_NULL, &masterPort);
  
  // Check to see if the "AppleClamshellClosed" property is in the PM root domain:
  rootDomain = IORegistryEntryFromPath(masterPort, kIOPowerPlane ":/IOPowerConnection/IOPMrootDomain");
  
  clamShellStateRef = IORegistryEntryCreateCFProperty( rootDomain,CFSTR(kAppleClamshellStateKey), kCFAllocatorDefault, 0);
  if (clamShellStateRef == NULL)
  {
    if ( rootDomain )
      IOObjectRelease(rootDomain);
    ioReturn = kIOReturnNoResources;
  }
  
  if ( CFBooleanGetValue( (CFBooleanRef)(clamShellStateRef) ) == true )
  {
    printf("closed!\n");
    isClosed = true;
  }
  
  if ( rootDomain )
    IOObjectRelease(rootDomain);
  
  if (clamShellStateRef)
    CFRelease(clamShellStateRef);
  return isClosed;
}