check_mysql: Fix segfault with old slaves (#2696823 - Oskar Ahner)

NEWS

@@ -28,6 +28,7 @@ This file documents the major additions and syntax changes between releases.
 	Fixed check_http not timing-out on redirects
 	Fixed negate not printing the real timeout in ALRM handler when left to default
 	negate timeout result is now configurable
+	Fixed segfault in check_mysql with old slaves (#2696823 - Oskar Ahner)
 
 1.4.13 25th Sept 2008
 	Fix Debian bug #460097: check_http --max-age broken (Hilko Bengen)

THANKS.in

@@ -248,3 +248,4 @@ Nik Soggia
 Olli Hauer
 Richard Edward Horner
 John Barbuto
+Oskar Ahner

plugins/check_mysql.c

@@ -177,13 +177,14 @@ main (int argc, char **argv)
 					continue;
 				}
 			}
+
 			if ((slave_io_field < 0) || (slave_sql_field < 0) || (num_fields == 0)) {
 				mysql_free_result (res);
 				mysql_close (&mysql);
 				die (STATE_CRITICAL, "Slave status unavailable\n");
 			}
 
-			snprintf (slaveresult, SLAVERESULTSIZE, "Slave IO: %s Slave SQL: %s Seconds Behind Master: %s", row[slave_io_field], row[slave_sql_field], row[seconds_behind_field]);
+			snprintf (slaveresult, SLAVERESULTSIZE, "Slave IO: %s Slave SQL: %s Seconds Behind Master: %s", row[slave_io_field], row[slave_sql_field], seconds_behind_field!=-1?row[seconds_behind_field]:"Unknown");
 			if (strcmp (row[slave_io_field], "Yes") != 0 || strcmp (row[slave_sql_field], "Yes") != 0) {
 				mysql_free_result (res);
 				mysql_close (&mysql);