// pointer to the host structure passed to us by the host application
OfxHost   *gHost;

// function called by the host application to set the host structure
static void
setHostFunc(OfxHost *hostStruct)
{
  gHost = hostStruct;
}

This section has the structure that holds information about the host application and allows us to fetch suites from the host. The setHostFunc is called by the host application to set this pointer and is passed to the host inside the OfxPlugin struct.