[Dovecot] Migrating password scheme

[Joseph Tam]

I tried the userdb prefetch / postlogin script method to do some password
manipulation, but it doesn't appear to work for me.  In particular, I
don't think this method works with

 	userdb {
 		driver = passwd-file
 		args = /path/to/passwd-file userdb_pw=%w
 	}

because it doesn't understand arbitrary var=value in the args
configuration.  Dvoecot seems to accept the entire string as the pathname
for a password file.  Is there a way to pass the plaintext password to
a post-login script using passwd-file userdb?

Before this, I managed password manipulation by process tracing dovecot's
auth process read() syscalls and parsing out the user/password from the
second buffer argument.  Quite a hack but it worked.

Joseph Tam <jtam.home at gmail.com>