From e545a60bf41bf6efe1e9d7730cc474bda9d3fc62 Mon Sep 17 00:00:00 2001
From: Alexey Botchkov <holyfoot@askmonty.org>
Date: Tue, 28 Apr 2020 16:08:18 +0400
Subject: [PATCH] MDEV-22236 JSON_ARRAYAGG query leads to SIGSEGV in
Charset::swap on optimized builds.
The json_arrayagg::val_str should handle NULL result.
---
mysql-test/main/func_json.result | 8 ++++++++
mysql-test/main/func_json.test | 8 ++++++++
sql/item_jsonfunc.cc | 15 ++++++++-------
3 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/mysql-test/main/func_json.result b/mysql-test/main/func_json.result
index be6ea1a7b61..716ae78a35c 100644
--- a/mysql-test/main/func_json.result
+++ b/mysql-test/main/func_json.result
@@ -1213,3 +1213,11 @@ DROP TABLE t1;
#
# End of 10.4 tests
#
+#
+# MDEV-16620 JSON_ARRAYAGG
+#
+CREATE TABLE t1 (a INT);
+SELECT JSON_ARRAYAGG(a) FROM t1;
+JSON_ARRAYAGG(a)
+NULL
+DROP TABLE t1;
diff --git a/mysql-test/main/func_json.test b/mysql-test/main/func_json.test
index fea33b899b2..2c5dbfbd42c 100644
--- a/mysql-test/main/func_json.test
+++ b/mysql-test/main/func_json.test
@@ -732,3 +732,11 @@ DROP TABLE t1;
--echo #
--echo # End of 10.4 tests
--echo #
+
+-- echo #
+-- echo # MDEV-16620 JSON_ARRAYAGG
+-- echo #
+
+CREATE TABLE t1 (a INT);
+SELECT JSON_ARRAYAGG(a) FROM t1;
+DROP TABLE t1;
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index a3b5d3b7fac..134c2573ea7 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -3632,13 +3632,14 @@ String* Item_func_json_arrayagg::convert_to_json(Item *item, String *res)
String* Item_func_json_arrayagg::val_str(String *str)
{
- str= Item_func_group_concat::val_str(str);
- String s;
- s.append('[');
- s.swap(*str);
- str->append(s);
- str->append(']');
-
+ if ((str= Item_func_group_concat::val_str(str)))
+ {
+ String s;
+ s.append('[');
+ s.swap(*str);
+ str->append(s);
+ str->append(']');
+ }
return str;
}
--
2.30.9