Index: ac.c
===================================================================
RCS file: /home/ncvs/src/usr.sbin/ac/ac.c,v
retrieving revision 1.27
diff -u -r1.27 ac.c
--- ac.c	3 Mar 2004 02:44:52 -0000	1.27
+++ ac.c	8 Mar 2004 07:36:23 -0000
@@ -83,6 +83,9 @@
 int			main(int, char **);
 int			ac(FILE *);
 struct tty_list		*add_tty(char *);
+#ifdef DEBUG
+const char		*debug_pfx(const struct utmp *, const struct utmp *);
+#endif
 int			do_tty(char *);
 FILE			*file(const char *);
 struct utmp_list	*log_in(struct utmp_list *, struct utmp *);
@@ -208,6 +211,72 @@
 	return up;
 }
 
+#ifdef DEBUG
+/*
+ * Create a string which is the standard prefix for a debug line.  It
+ * includes a timestamp (perhaps with year), device-name, and user-name.
+ */
+const char *
+debug_pfx(const struct utmp *event_up, const struct utmp *dev_up)
+{
+	static char str_result[40+UT_LINESIZE+UT_NAMESIZE];
+	static char thisyear[5];
+	size_t maxcopy;
+	time_t ut_timecopy;
+
+	if (thisyear[0] == '\0') {
+		/* Figure out what "this year" is. */
+		time(&ut_timecopy);
+		strlcpy(str_result, ctime(&ut_timecopy), sizeof(str_result));
+		strlcpy(thisyear, &str_result[20], sizeof(thisyear));
+	}
+
+	if (event_up->ut_time == 0)
+		strlcpy(str_result, "*ZeroTime* --:--:-- ", sizeof(str_result));
+	else {
+		/*
+		* The type of utmp.ut_time is not necessary type time_t, as
+		* it is explicitly defined as type int32_t.  Copy the value
+		* for platforms where sizeof(time_t) != sizeof(int32_t).
+		*/
+		ut_timecopy = _time32_to_time(event_up->ut_time);
+		strlcpy(str_result, ctime(&ut_timecopy), sizeof(str_result));
+		/*
+		 * Include the year, if it is not the same year as "now".
+		 */
+		if (strncmp(&str_result[20], thisyear, 4) == 0)
+			str_result[20] = '\0';
+		else {
+			str_result[24] = ' ';		/* Replace a '\n' */
+			str_result[25] = '\0';
+		}
+	}
+
+	if (dev_up->ut_line[0] == '\0')
+		strlcat(str_result, "NoDev", sizeof(str_result));
+	else {
+		/* ut_line is not necessarily null-terminated. */
+		maxcopy = strlen(str_result) + UT_LINESIZE + 1;
+		if (maxcopy > sizeof(str_result))
+			maxcopy = sizeof(str_result);
+		strlcat(str_result, dev_up->ut_line, maxcopy);
+	}
+	strlcat(str_result, ": ", sizeof(str_result));
+
+	if (dev_up->ut_name[0] == '\0')
+		strlcat(str_result, "LogOff", sizeof(str_result));
+	else {
+		/* ut_name is not necessarily null-terminated. */
+		maxcopy = strlen(str_result) + UT_NAMESIZE + 1;
+		if (maxcopy > sizeof(str_result))
+			maxcopy = sizeof(str_result);
+		strlcat(str_result, dev_up->ut_name, maxcopy);
+	}
+
+	return (str_result);
+}
+#endif
+
 int
 main(int argc, char *argv[])
 {
@@ -346,11 +415,10 @@
 			Users = update_user(Users, lp->usr.ut_name, secs);
 #ifdef DEBUG
 			if (Debug)
-				printf("%-.*s %-.*s: %-.*s logged out (%2d:%02d:%02d)\n",
-				    19, ctime(&up->ut_time),
-				    sizeof (lp->usr.ut_line), lp->usr.ut_line,
-				    sizeof (lp->usr.ut_name), lp->usr.ut_name,
-				    secs / 3600, (secs % 3600) / 60, secs % 60);
+				printf("%s logged out (%2d:%02d:%02d)\n",
+				    debug_pfx(up, &lp->usr), (int)(secs / 3600),
+				    (int)((secs % 3600) / 60),
+				    (int)(secs % 60));
 #endif
 			/*
 			 * now lose it
@@ -426,11 +494,10 @@
 	memmove((char *)&lp->usr, (char *)up, sizeof (struct utmp));
 #ifdef DEBUG
 	if (Debug) {
-		printf("%-.*s %-.*s: %-.*s logged in", 19,
-		    ctime(&lp->usr.ut_time), sizeof (up->ut_line),
-		    up->ut_line, sizeof (up->ut_name), up->ut_name);
+		printf("%s logged in", debug_pfx(&lp->usr, up));
 		if (*up->ut_host)
-			printf(" (%-.*s)", sizeof (up->ut_host), up->ut_host);
+			printf(" (%-.*s)", (int)sizeof(up->ut_host),
+			    up->ut_host);
 		putchar('\n');
 	}
 #endif
@@ -443,21 +510,66 @@
 	struct utmp_list *lp, *head = NULL;
 	struct utmp usr;
 	struct tm *ltm;
-	time_t secs;
-	int day = -1;
+	time_t prev_secs, secs, ut_timecopy;
+	int day, rfound, tchanged, tskipped;
 
+	day = -1;
+	prev_secs = 1;			/* Minimum acceptable date == 1970 */
+	rfound = tchanged = tskipped = 0;
+	secs = 0;
 	while (fread((char *)&usr, sizeof(usr), 1, fp) == 1) {
+		rfound++;
+		/*
+		 * The type of utmp.ut_time is not necessary type time_t,
+		 * it is explicitly defined as type int32_t.  Copy the value
+		 * for platforms where sizeof(time_t) != size(int32_t).
+		 */
+		ut_timecopy = _time32_to_time(usr.ut_time);
+		/*
+		 * When sparc64 went to 64-bit time_t's, there was some
+		 * routine which saved ut_time==0 (the high-order word)
+		 * instead of the real time.  For those wtmp files, it
+		 * was found to be "more-accurate" to substitute the
+		 * most-recent time found, instead of throwing away
+		 * the record.  It is still just a guess, but it is a
+		 * better guess than (for instance) throwing away some
+		 * log-off record, and thus charging someone as if they
+		 * remained logged on until the next reboot or the end
+		 * of the month.
+		 */
+		if (ut_timecopy == 0 && prev_secs > 1) {
+#ifdef DEBUG
+			if (Debug)
+				printf("%s - date changed to: %s",
+				    debug_pfx(&usr, &usr), ctime(&prev_secs));
+#endif
+			tchanged++;
+			usr.ut_time = ut_timecopy = prev_secs;
+		}
+		/*
+		 * Skip records where the time goes backwards.
+		 */
+		if (ut_timecopy < prev_secs) {
+#ifdef DEBUG
+			if (Debug)
+				printf("%s - bad date, record skipped\n",
+				    debug_pfx(&usr, &usr));
+#endif
+			tskipped++;
+			continue;	/* Skip this invalid record. */
+		}
+		prev_secs = ut_timecopy;
+
 		if (!FirstTime)
-			FirstTime = usr.ut_time;
+			FirstTime = ut_timecopy;
 		if (Flags & AC_D) {
-			time_t t = _int_to_time(usr.ut_time);
-			ltm = localtime(&t);
+			ltm = localtime(&ut_timecopy);
 			if (day >= 0 && day != ltm->tm_yday) {
 				day = ltm->tm_yday;
 				/*
 				 * print yesterday's total
 				 */
-				secs = usr.ut_time;
+				secs = ut_timecopy;
 				secs -= ltm->tm_sec;
 				secs -= 60 * ltm->tm_min;
 				secs -= 3600 * ltm->tm_hour;
@@ -467,10 +579,10 @@
 		}
 		switch(*usr.ut_line) {
 		case '|':
-			secs = usr.ut_time;
+			secs = ut_timecopy;
 			break;
 		case '{':
-			secs -= usr.ut_time;
+			secs -= ut_timecopy;
 			/*
 			 * adjust time for those logged in
 			 */
@@ -479,7 +591,7 @@
 			break;
 		case '~':			/* reboot or shutdown */
 			head = log_out(head, &usr);
-			FirstTime = usr.ut_time; /* shouldn't be needed */
+			FirstTime = ut_timecopy; /* shouldn't be needed */
 			break;
 		default:
 			/*
@@ -491,6 +603,12 @@
 				    strchr("pqrsPQRS", usr.ut_line[3]) != 0 ||
 				    *usr.ut_host != '\0')
 					head = log_in(head, &usr);
+#ifdef DEBUG
+				else if (Debug > 1)
+					/* Things such as 'screen' sessions. */
+					printf("%s ignored\n",
+					    debug_pfx(&usr, &usr));
+#endif
 			} else
 				head = log_out(head, &usr);
 			break;
@@ -502,13 +620,13 @@
 	(void)strcpy(usr.ut_line, "~");
 
 	if (Flags & AC_D) {
-		time_t t = _int_to_time(usr.ut_time);
-		ltm = localtime(&t);
+		ut_timecopy = _time32_to_time(usr.ut_time);
+		ltm = localtime(&ut_timecopy);
 		if (day >= 0 && day != ltm->tm_yday) {
 			/*
 			 * print yesterday's total
 			 */
-			secs = usr.ut_time;
+			secs = ut_timecopy;
 			secs -= ltm->tm_sec;
 			secs -= 60 * ltm->tm_min;
 			secs -= 3600 * ltm->tm_hour;
@@ -527,6 +645,14 @@
 			show_users(Users);
 		show("total", Total);
 	}
+
+	if (tskipped > 0)
+		printf("(Skipped %d of %d records due to invalid time values)\n",
+		    tskipped, rfound);
+	if (tchanged > 0)
+		printf("(Changed %d of %d records to have a more likely time value)\n",
+		    tchanged, rfound);
+
 	return 0;
 }