how to detect if a file is complete

[harm]

Hi all,

I want to copy some files from one dir to another using python. 
The files are copied onto my linux box via a samba-share.

I want to write a python script which checks a dir and copies all
files to another dir. But there is the possibility that the file is
not yet complete. (This are rather large Postscript files >100mb).
Therefore I need to detect if the file is complete.

The files are copied on the samba-share by Adobe Acrobat Distiller,
therefore i cannot save some check file like $FILENAME.complete...

Is there some other way (using python) to detect if the file is
complete?

Thanks,

Harm de Laat
Informatiefabriek
The Netherlands