GIOChannel and german umlauts

[Tilman Sauerbeck <tilman code-monkey de>]

Hi,
I'm writing an application that uses GIOChannel for communication over
a socket.
On the other side, input is sent as ISO-8859-1.

In my app, I'm not setting a encoding for the GIOChannel, i.e. encoding
is NULL. Now when I'm sending or receiving text that contains special
characters such as german umlauts, my application segfaults when
LC_CTYPE is not set to a locale that supports those characters:
e.g., when running with LC_CTYPE=de_DE it's working fine while running
with LC_CTYPE=POSIX will crash.

Setting the GIOChannels encoding to ISO-8859-1 doesn't help either.

Is there a method generally used to fix this?

Thanks in advance,
        Tilman