Add a new library: libulog.

One of the things I really want to do, is to get rid of the limitations
of our current utmp(5) mechanism:

- It only allows 8 byte TTY device names.
- The hostname only allows 16 bytes of storage.

I'm not a big fan of <utmpx.h>, but I think we should at least try to
add parts of it. Unfortunately we cannot implement <utmpx.h>, because we
miss various fields, such as ut_id, ut_pid, etc. The API provided by
libulog shares some similarities with <utmpx.h>, so it shouldn't be too
hard to port these applications eventually. In most simple cases, it
should just be a matter of removing the ulog_ prefix everywhere.

As a bonus, it also implements a function called ulog_login_pseudo(),
which allows unprivileged applications to write log entries, provided
they have a valid file descriptor to a pseudo-terminal master device.

libulog will allow a smoother transition to a new file format by adding
a library interface to deal with utmp/wtmp/lastlog files. I initially
thought about adding the functionality to libutil, but because I'm not
planning on keeping this library around forever, we'd better keep it
separated.

Next items on the todo list:

1. Port applications in the base system (and ports) to libulog, instead
   of letting them use <utmp.h>.
2. Remove <utmp.h>, implement <utmpx.h> and reimplement this library on
   top.
3. Port as many applications as possible back to <utmpx.h>.

1 files changed, 102 insertions, 0 deletions

diff --git a/lib/libulog/ulog_login.3 b/lib/libulog/ulog_login.3
new file mode 100644
index 0000000..ca896fe
--- /dev/null
+++ b/lib/libulog/ulog_login.3
@@ -0,0 +1,102 @@
+.\" Copyright (c) 2009 Ed Schouten <ed@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 2, 2009
+.Os
+.Dt ULOG_LOGIN 3
+.Sh NAME
+.Nm ulog_login ,
+.Nm ulog_login_pseudo ,
+.Nm ulog_logout ,
+.Nm ulog_logout_pseudo
+.Nd manage user login records
+.Sh LIBRARY
+.Lb libulog
+.Sh SYNOPSIS
+.In ulog.h
+.Ft void
+.Fn ulog_login "const char *line" "const char *user" "const char *host"
+.Ft void
+.Fn ulog_login_pseudo "int fd" "const char *host"
+.Ft void
+.Fn ulog_logout "const char *line"
+.Ft void
+.Fn ulog_logout_pseudo "int fd"
+.Sh DESCRIPTION
+The
+.Fn ulog_login
+and
+.Fn ulog_login_pseudo
+functions register a login session on a TTY.
+The
+.Fn ulog_login
+function adds an entry for TTY
+.Fa line
+and username
+.Fa user .
+The
+.Fn ulog_login_pseudo
+function uses file descriptor to a pseudo-terminal master device
+.Fa fd
+to determine the TTY name, while using the username belonging to the
+real user ID of the calling process.
+The optional
+.Fa host
+argument denotes a remote hostname, in case the login session is
+provided by a network service.
+.Pp
+The
+.Fn ulog_logout
+and
+.Fn ulog_logout_pseudo
+functions mark the previously registered login session as being
+terminated.
+.Pp
+Because the
+.Fa line
+and
+.Fa user
+arguments of
+.Fn ulog_login
+and
+.Fn ulog_logout
+cannot be trusted, these functions require administrative privileges.
+The
+.Fn ulog_login_pseudo
+and
+.Fn ulog_logout_pseudo
+functions spawn a privileged process to perform the actual logging.
+.Sh SEE ALSO
+.Xr getuid 3 ,
+.Xr login 3 ,
+.Xr logout 3 ,
+.Xr posix_openpt 2 ,
+.Xr ptsname 3 ,
+.Xr ulog_getutxent 3 ,
+.Xr utmp 5
+.Sh HISTORY
+These functions appeared in
+.Fx 9.0 .