what is magical about kadmin.local?

[Chris Hecker]

I am trying to reproduce the "don't need to enter a password" behavior 
of kadmin.local and I can't seem to get it to work.  If I just run 
kadmin.local with no parameters, it eventually calls 
kadm5_init_with_password with a default root/admin at FOO.COM principal, 
null password and service name, and the default initialized params 
structure with just the realm in it.

I have almost 100% copied kadmin.c into a separate program, and I call 
kadm5_init_with_password with the exact same parameters, but my version 
fails and kadmin.local's doesn't (mine fails because root/admin isn't a 
valid krb account, but if I enter a valid admin princ it prompts for a 
password, and kadmin.local doesn't prompt or error on a valid or invalid 
principal).  I must be missing something stupid, but I can't figure out 
what it is, the calls seem identical.

Anybody have any ideas?

Thanks,
Chris