Just ignore the timestamps given to pututxline().

I've noticed many applications do a bad job at timekeeping, for several
reasons:

- Applications like screen(1) don't update time records when restoring
  the old user login record.
- Many applications only set ut_tv.tv_sec, not ut_tv.tv_usec.

This causes many problems for tools such as ac(8), which require the
timestamps to be properly ordered. This is why I've decided to let the
utmpx code obtain valid timestamps itself.

3 files changed, 12 insertions, 23 deletions

diff --git a/lib/libc/gen/getutxent.3 b/lib/libc/gen/getutxent.3
index 7436142..37080bb 100644
--- a/lib/libc/gen/getutxent.3
+++ b/lib/libc/gen/getutxent.3
@@ -311,13 +311,9 @@ will only be written to
 Entries of type
 .Dv USER_PROCESS
 will also be written to
-.Pa /var/run/utx.active .
-It will only be written to
-.Pa /var/log/utx.lastlogin
-if
-.Fa ut_tv
-for that user has a greater value than the existing entry or when no
-entry for the user has been found.
+.Pa /var/run/utx.active
+and
+.Pa /var/log/utx.lastlogin .
 .Pp
 Entries of type
 .Dv DEAD_PROCESS
@@ -345,6 +341,8 @@ to be discarded.
 All entries whose type has not been mentioned previously, are discarded
 by this implementation of
 .Fn pututxline .
+This implementation also ignores the value of
+.Fa ut_tv .
 .Sh RETURN VALUES
 The
 .Fn getutxent ,
diff --git a/lib/libc/gen/pututxline.c b/lib/libc/gen/pututxline.c
index 1239531..ce4dc28 100644
--- a/lib/libc/gen/pututxline.c
+++ b/lib/libc/gen/pututxline.c
@@ -132,13 +132,6 @@ utx_active_remove(struct futx *fu)
 			if (memcmp(fu->fu_id, fe.fu_id, sizeof fe.fu_id) != 0)
 				continue;
 
-			/*
-			 * Prevent login sessions from having a negative
-			 * timespan.
-			 */
-			if (be64toh(fu->fu_tv) < be64toh(fe.fu_tv))
-				fu->fu_tv = fe.fu_tv;
-
 			/* Terminate session. */
 			fseeko(fp, -(off_t)sizeof fe, SEEK_CUR);
 			fwrite(fu, sizeof *fu, 1, fp);
@@ -175,17 +168,12 @@ utx_lastlogin_add(const struct futx *fu)
 	while (fread(&fe, sizeof fe, 1, fp) == 1) {
 		if (strncmp(fu->fu_user, fe.fu_user, sizeof fe.fu_user) != 0)
 			continue;
-
-		/* Prevent lowering the time value. */
-		if (be64toh(fu->fu_tv) <= be64toh(fe.fu_tv))
-			goto done;
 		
 		/* Found a previous lastlogin entry for this user. */
 		fseeko(fp, -(off_t)sizeof fe, SEEK_CUR);
 		break;
 	}
 	fwrite(fu, sizeof *fu, 1, fp);
-done:
 	fclose(fp);
 }
 
diff --git a/lib/libc/gen/utxdb.c b/lib/libc/gen/utxdb.c
index 49118ff..6a85c05 100644
--- a/lib/libc/gen/utxdb.c
+++ b/lib/libc/gen/utxdb.c
@@ -30,6 +30,7 @@ __FBSDID("$FreeBSD$");
 #include "namespace.h"
 #include <sys/endian.h>
 #include <sys/param.h>
+#include <sys/time.h>
 #include <stdlib.h>
 #include <string.h>
 #include <utmpx.h>
@@ -50,9 +51,11 @@ __FBSDID("$FreeBSD$");
 #define	UTOF_TYPE(ut, fu) do { \
 	(fu)->fu_type = (ut)->ut_type;					\
 } while (0)
-#define	UTOF_TV(ut, fu) do { \
-	(fu)->fu_tv = htobe64((uint64_t)(ut)->ut_tv.tv_sec * 1000000 +	\
-	    (uint64_t)(ut)->ut_tv.tv_usec);				\
+#define	UTOF_TV(fu) do { \
+	struct timeval tv;						\
+	gettimeofday(&tv, NULL);					\
+	(fu)->fu_tv = htobe64((uint64_t)tv.tv_sec * 1000000 +		\
+	    (uint64_t)tv.tv_usec);					\
 } while (0)
 
 void
@@ -96,7 +99,7 @@ utx_to_futx(const struct utmpx *ut, struct futx *fu)
 	}
 
 	UTOF_TYPE(ut, fu);
-	UTOF_TV(ut, fu);
+	UTOF_TV(fu);
 }
 
 #define	FTOU_STRING(fu, ut, field) do { \