how to determine if the output has been flushed normally...

Hi, I'm dealing with the following issue: how to determine whether the current page request has been responded normally, eg. output has been sent to the browser as regular, or just a redirection header sent to it header('Location: '); ? Some words about the background: This functinality would be implemented in my error handler class which does not depend on any application framework, or programming style, or whatsoever. And it must be used within a callback function by nature of error-handling. So I'm seeking for a native PHP solution (mostly a function), but any suggestions are welcome. -- gerzson