Bug#26346: stack + buffer overrun in mysqldump

Fixes to buffer overlows from long command line args, and unchecked dyn_str return codes. Also light refactoring.

mysql-test/r/mysqldump.result

@@ -1567,29 +1567,17 @@ create table t3(a varchar(30) primary key, b int not null);
 test_sequence
 ------ Testing with illegal table names ------
 mysqldump: Couldn't find table: "\d-2-1.sql"
-
 mysqldump: Couldn't find table: "\t1"
-
 mysqldump: Couldn't find table: "\t1"
-
 mysqldump: Couldn't find table: "\\t1"
-
 mysqldump: Couldn't find table: "t\1"
-
 mysqldump: Couldn't find table: "t\1"
-
 mysqldump: Couldn't find table: "t/1"
-
 mysqldump: Couldn't find table: "T_1"
-
 mysqldump: Couldn't find table: "T%1"
-
 mysqldump: Couldn't find table: "T'1"
-
 mysqldump: Couldn't find table: "T_1"
-
 mysqldump: Couldn't find table: "T_"
-
 test_sequence
 ------ Testing with illegal database names ------
 mysqldump: Got error: 1049: Unknown database 'mysqldump_test_d' when selecting the database
@@ -3218,5 +3206,12 @@ INSERT INTO t1 VALUES(1,0xff00fef0);
 </mysqldump>
 DROP TABLE t1;
 #
+# Bug#26346:  	stack + buffer overrun in mysqldump
+#
+CREATE TABLE t1(a int);
+INSERT INTO t1 VALUES (1), (2);
+mysqldump: Input filename or options too long: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+DROP TABLE t1;
+#
 # End of 5.0 tests
 #