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, 87 insertions, 0 deletions

diff --git a/lib/libulog/ulog.h b/lib/libulog/ulog.h
new file mode 100644
index 000000000000..2a613ddf46ca
--- /dev/null
+++ b/lib/libulog/ulog.h
@@ -0,0 +1,87 @@
+/*-
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _ULOG_H_
+#define	_ULOG_H_
+
+#include <sys/cdefs.h>
+#include <sys/_timeval.h>
+
+/*
+ * libulog.
+ *
+ * This library is provided as a migratory tool towards <utmpx.h>.  We
+ * cannot yet implement <utmpx.h>, because our on-disk file format lacks
+ * various fields.  <utmpx.h> also has some shortcomings.  Ideally we
+ * want to allow logging of user login records generated by unprivileged
+ * processes as well, provided that they hold a file descriptor to a
+ * pseudo-terminal master device.
+ *
+ * Unlike struct utmpx, the buffers containing the strings are not
+ * stored inside struct ulog_utmpx itself.  Processes should never
+ * handcraft these structures anyway.
+ *
+ * This library (or at least parts of it) will hopefully deprecate over
+ * time, when we provide the <utmpx.h> API.
+ */
+
+#define	_UTX_USERDISPSIZE	16
+#define	_UTX_LINEDISPSIZE	8
+#define	_UTX_HOSTDISPSIZE	16
+
+struct ulog_utmpx {
+	char		*ut_user;
+#if 0
+	char		*ut_id;
+#endif
+	char		*ut_line;
+	char		*ut_host;
+#if 0
+	pid_t		 ut_pid;
+	short		 ut_type;
+#endif
+	struct timeval	 ut_tv;
+};
+
+__BEGIN_DECLS
+void	ulog_endutxent(void);
+struct ulog_utmpx *ulog_getutxent(void);
+#if 0
+struct ulog_utmpx *ulog_getutxid(const struct ulog_utmpx *id);
+struct ulog_utmpx *ulog_getutxline(const struct ulog_utmpx *line);
+struct ulog_utmpx *ulog_pututxline(const struct ulog_utmpx *utmpx);
+#endif
+void	ulog_setutxent(void);
+
+void	ulog_login(const char *, const char *, const char *);
+void	ulog_login_pseudo(int, const char *);
+void	ulog_logout(const char *);
+void	ulog_logout_pseudo(int);
+__END_DECLS
+
+#endif /* !_ULOG_H_ */