[Dovecot] Trying to modify the source - fopen problems

Hello all,

I don't know if this needs to be sent to a different list or not, if so, please let me know.

Anyways, I'm trying to modify the dovecot source a bit, but the problem I'm having is that whenever I use "fopen", it always returns NULL. I've tried a variety of things, even fopen("/dev/null", "w") -- because that should almost always work. I'm trying to get it to work in src/pop3-login/client-authenticate.c

Any idea why this might be happening? Any suggestions as to where to put the code instead? (I'm trying to check the username against some information in a file OR pass the username to a process and have it do the work)

Thanks, Phillip