This patch provides the remote user ID and remote user home directory information of the authenticated user to the calling application. Used by extending the "passwdcolumn" during the AUTH phase, and populates two PAM environment context variables VUID and VHOME based on the existence of a second and third column in the AUTH SQL select.
In a nutshell, this means that a calling application (see my next patch at vsftp) can retrieve and use UID and Home directory information direct from the PAM authentication module.
Technically it's generic enough that you can choose any two SQL columns (or expressions), and pass this information along to the calling application.
Patched against pam_mysql-0.7RC1.