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, 135 insertions, 0 deletions

diff --git a/lib/libulog/ulog_login.c b/lib/libulog/ulog_login.c
new file mode 100644
index 0000000..22de619
--- /dev/null
+++ b/lib/libulog/ulog_login.c
@@ -0,0 +1,135 @@
+/*-
+ * 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <fcntl.h>
+#include <inttypes.h>
+#include <paths.h>
+#include <pwd.h>
+#include <string.h>
+#include <unistd.h>
+#include <time.h>
+#include <timeconv.h>
+#include <ttyent.h>
+
+#include "ulog_internal.h"
+
+void
+ulog_login(const char *line, const char *user, const char *host)
+{
+	struct futmp fu;
+	struct flastlog fl;
+	int fd;
+
+	/* Remove /dev/ component. */
+	if (strncmp(line, _PATH_DEV, sizeof _PATH_DEV - 1) == 0)
+		line += sizeof _PATH_DEV - 1;
+
+	/* Prepare log entries. */
+	memset(&fu, 0, sizeof fu);
+	strlcpy(fu.ut_line, line, sizeof fu.ut_line);
+	strlcpy(fu.ut_user, user, sizeof fu.ut_user);
+	if (host != NULL)
+		strlcpy(fu.ut_host, host, sizeof fu.ut_host);
+	fu.ut_time = _time_to_time32(time(NULL));
+
+	fl.ll_time = fu.ut_time;
+	memcpy(fl.ll_line, fu.ut_line, sizeof fl.ll_line);
+	memcpy(fl.ll_host, fu.ut_host, sizeof fl.ll_host);
+
+	/* Update utmp entry. */
+	if ((fd = open(_PATH_UTMP, O_WRONLY|O_CREAT, 0644)) >= 0) {
+		struct ttyent *ty;
+		int idx;
+
+		setttyent();
+		for (idx = 1; (ty = getttyent()) != NULL; ++idx) {
+			if (strcmp(ty->ty_name, line) != 0)
+				continue;
+			lseek(fd, (off_t)(idx * sizeof fu), L_SET);
+			write(fd, &fu, sizeof fu);
+			break;
+		}
+		endttyent();
+		close(fd);
+	}
+
+	/* Add wtmp entry. */
+	if ((fd = open(_PATH_WTMP, O_WRONLY|O_APPEND, 0)) >= 0) {
+		write(fd, &fu, sizeof fu);
+		close(fd);
+	}
+
+	/* Update lastlog entry. */
+	if ((fd = open(_PATH_LASTLOG, O_WRONLY, 0)) >= 0) {
+		struct passwd *pw;
+
+		pw = getpwnam(user);
+		if (pw != NULL) {
+			lseek(fd, (off_t)(pw->pw_uid * sizeof fl), L_SET);
+			write(fd, &fl, sizeof fl);
+		}
+		close(fd);
+	}
+}
+
+void
+ulog_logout(const char *line)
+{
+	struct futmp ut;
+	int fd, found;
+
+	/* Remove /dev/ component. */
+	if (strncmp(line, _PATH_DEV, sizeof _PATH_DEV - 1) == 0)
+		line += sizeof _PATH_DEV - 1;
+
+	/* Mark entry in utmp as logged out. */
+	if ((fd = open(_PATH_UTMP, O_RDWR, 0)) < 0)
+		return;
+	found = 0;
+	while (read(fd, &ut, sizeof ut) == sizeof ut) {
+		if (ut.ut_user[0] == '\0' ||
+		    strncmp(ut.ut_line, line, sizeof ut.ut_line) != 0)
+			continue;
+		memset(ut.ut_user, 0, sizeof ut.ut_user);
+		memset(ut.ut_host, 0, sizeof ut.ut_host);
+		ut.ut_time = _time_to_time32(time(NULL));
+		lseek(fd, -(off_t)sizeof ut, L_INCR);
+		write(fd, &ut, sizeof ut);
+		found = 1;
+	}
+	close(fd);
+	if (!found)
+		return;
+
+	/* utmp entry found. Also add logout entry to wtmp. */
+	if ((fd = open(_PATH_WTMP, O_WRONLY|O_APPEND, 0)) >= 0) {
+		write(fd, &ut, sizeof ut);
+		close(fd);
+	}
+}