newsyslog: fix one hour rotation with frequent execution

If a newsyslog.conf(5) has an entry that is configured to be rotated every
hour, and crontab(8) is set to execute newsyslog several times per hour,
the logic of age_old_log() is broken and it would rotate the entry too
often.  AFAIU, the extra 1800 seconds were added to allow some leeway for
the previous newsyslog invocation, that could have been too slow and the
timestamp on the old file is newer than actual time of the previous
newsyslog invocation.  But 30 minutes of leeway is way to much.  Reduce
this down to 3 minutes, which would be a compromise between a potential
need to run newsyslogd every 5 minutes and a situation when newsyslog
takes a significant time to rotate the logs.

Provide a test case for that.

Reviewed by:		delphij
Differential Revision:	https://reviews.freebsd.org/D52700

usr.sbin/newsyslog/newsyslog.c

@@ -2615,7 +2615,7 @@ age_old_log(const char *file)
 		mtime = sb.st_mtime;
 	}
 
-	return ((int)(ptimeget_secs(timenow) - mtime + 1800) / 3600);
+	return ((int)(ptimeget_secs(timenow) - mtime + 180) / 3600);
 }
 
 /* Skip Over Blanks */

usr.sbin/newsyslog/tests/legacy_test.sh

@@ -417,6 +417,51 @@ tests_time_rotate() {
 	tmpdir_clean
 }
 
+tests_interval_rotate() {
+	local hours ext h
+
+	hours="$1"
+	ext="$2"
+
+	tmpdir_create
+
+	begin "create file" -newdir
+	run_newsyslog -C
+	ckfe ${LOGFNAME}
+	end
+
+	# old file doesn't exist - forced rotation
+	begin "rotate interval 0"
+	run_newsyslog
+	ckfe ${LOGFNAME}
+	chkfcnt 1 ${dir}${LOGFNAME}.*
+	end
+
+	# emulate newsyslog runs every 5 minutes
+	begin "rotate interval less than ${hours} hours"
+	m=0
+	while [ $(expr ${m} / 60 ) -lt ${hours} ]; do
+		touch -t $(date -v -${m}M +%Y%m%d%H%M) ${LOGFNAME}.0
+		run_newsyslog
+		ckfe ${LOGFNAME}
+		chkfcnt 1 ${dir}${LOGFNAME}.*
+		if [ $OK != 1 ]; then
+			break;
+		fi
+		m=$(expr ${m} + 5)
+	done
+	end
+
+	begin "rotate interval ${hours} hours"
+	touch -t $(date -v -${hours}H +%Y%m%d%H%M) ${LOGFNAME}.0
+	run_newsyslog
+	ckfe ${LOGFNAME}
+	chkfcnt 2 ${dir}${LOGFNAME}.*
+	end
+
+	tmpdir_clean
+}
+
 tests_rfc5424() {
 	local dir ext name_postfix newsyslog_args
 
@@ -526,7 +571,7 @@ tests_normal_rotate_recompress() {
 	tmpdir_clean
 }
 
-echo 1..185
+echo 1..193
 mkdir -p ${TMPDIR}
 cd ${TMPDIR}
 
@@ -638,4 +683,10 @@ tests_p_flag_rotate ".gz"
 echo "$LOGFPATH 640  3     *    @T00  NCZ" > newsyslog.conf
 tests_normal_rotate_recompress
 
+# Interval based rotation
+echo "$LOGFPATH	640  3	   *	1  NC" > newsyslog.conf
+tests_interval_rotate 1
+echo "$LOGFPATH	640  3	   *	2  NC" > newsyslog.conf
+tests_interval_rotate 2
+
 rm -rf "${TMPDIR}"