Puzzling form/cgi problem

[Dfenestr8]

Hi.

I have a problem with a subroutine in a cgi script that's supposed to
return the byte location at the end of a file, which the script then
stores as a hidden input on a web form.

Unfortunately, even though it works fine in the python shell, in the
cgi-script it always returns "0". That's no use to me at all.

Here's the subroutine......

def getLastByteLoc(log):
	#open log file
	f = open(log)
	
	#seek to end of log file.
	f.seek(0,2)
	
	location = f.tell()
	f.close()
	return location