question about encoding

[Axel <axel azerty netcourrier com>]

hi
I m trying to open and read file which contains accentued characters 
like éèùà
so
I open a file, with GIOChannel and read the strings
but what is the function to get the encoding ?
I didn' t found it in API
I have seen call to convert to utf8 but it needs the original encoding 
from the string, and I didn' t found how to get it.
Someone could help me ?
Thanks

Axel