Bug#20752: BENCHMARK with many iterations returns too quickly

In BENCHMARK(count, expr), count could overflow/wrap-around.
Patch changes to a sufficiently large data-type. Adds a warning
for negative count values.


mysql-test/r/func_str.result:
  show that a negative 'count' for BENCHMARK(count, expr)
  throws a warning and returns NULL.
mysql-test/t/func_str.test:
  show that a negative 'count' for BENCHMARK(count, expr)
  throws a warning and returns NULL.
sql/item_func.cc:
  use ulonglong rather than ulong in BENCHMARK(count, expr)
  throw warning on negative 'count'; return SQL-NULL.

1 files changed, 7 insertions, 0 deletions

diff --git a/mysql-test/t/func_str.test b/mysql-test/t/func_str.test
index b6da14211ae..5a5f4024bc4 100644
--- a/mysql-test/t/func_str.test
+++ b/mysql-test/t/func_str.test
@@ -875,6 +875,13 @@ select benchmark(100, NULL);
 select benchmark(NULL, 1+1);
 
 #
+# Bug #20752: BENCHMARK with many iterations returns too quickly
+#
+
+# not a string, but belongs with the above Bug#22684
+select benchmark(-1, 1);
+
+#
 # Please note:
 # 1) The collation of the password is irrelevant, the encryption uses
 # the binary representation of the string without charset/collation.