Subject: Re: utmp file format change
To: James Graham <>
From: Noriyuki Soda <>
List: tech-userlevel
Date: 08/23/2001 05:18:37
>>>>> On Wed, 22 Aug 2001 13:10:30 -0700 (PDT),
	James Graham <> said:

> So why don't we have utmp/wtmp writing facilities in libc and use those
> instead of writing directly?

That is not enough, because

	- it doesn't provide binary compatibilty with old binaries.
	- it cannot make utmp format changeable, because libc may be
	  statically linked.

What we have to do is:
	- keep old utmp format
	- provide API to access (extended) utmp information
	- split implmentation of the API from libc,
	  by one of the following ways:
		1. make a daemon to touch utmp information,
		  and access the daemon via socket.
		2. make a shared object module to touch utmp
		  information, and access the module via dlopen(3).
		3. only provide the API via shared object.
		  (do not permit to link it statically).
	  Unfortuntely, 2 and 3 won't work with platforms which
	  don't provide dynamic linking. So, probably 1 is the
	  only choice.