Bug#32757: hang with sql_mode set when setting some global variables

If setting a system-variable provided by a plug-in failed, no OK or
error was sent in some cases, hanging the client. We now send an error
in the case from the ticket (integer-argument out of range in STRICT
mode). We also provide a semi-generic fallback message for possible
future cases like this where an error is signalled, but no message is
sent to the client. The error/warning handling is unified so it's the
same again for variables provided by plugins and those in the server
proper.


mysql-test/r/plugin.result:
  show that on out-of-range values, plugin interface throws errors
  in STRICT mode and warnings otherwise.
mysql-test/t/plugin.test:
  show that on out-of-range values, plugin interface throws errors
  in STRICT mode and warnings otherwise.
sql/set_var.cc:
  - handle signedness of values used in warnings
  - in STRICT mode, throw errors rather than warnings
sql/sql_parse.cc:
  If sql_set_variables() returns with an error but no message
  was sent to the client, send a semi-generic one so the session
  won't hang and we won't fail silently.
sql/sql_plugin.cc:
  throw a warning if more than just block-size was corrected
  (or an error in STRICT mode). use functions from set_var
  for uniform behaviour of server- and plug-in variables.
storage/example/ha_example.cc:
  Add a ULONG system variable to example plugin so
  we can test integers in the plugin-interface without
  having to depend on the presence of innobase.

1 files changed, 27 insertions, 0 deletions

diff --git a/mysql-test/r/plugin.result b/mysql-test/r/plugin.result
index e4af1535775..782d2a5a9a4 100644
--- a/mysql-test/r/plugin.result
+++ b/mysql-test/r/plugin.result
@@ -27,3 +27,30 @@ SET GLOBAL example_enum_var= e2;
 SET GLOBAL example_enum_var= impossible;
 ERROR 42000: Variable 'enum_var' can't be set to the value of 'impossible'
 UNINSTALL PLUGIN example;
+INSTALL PLUGIN example SONAME 'ha_example.so';
+select @@session.sql_mode into @old_sql_mode;
+set session sql_mode='';
+set global example_ulong_var=500;
+select @@global.example_ulong_var;
+@@global.example_ulong_var
+500
+set global example_ulong_var=1111;
+Warnings:
+Warning	1292	Truncated incorrect ulong_var value: '1111'
+select @@global.example_ulong_var;
+@@global.example_ulong_var
+1000
+set session sql_mode='STRICT_ALL_TABLES';
+set global example_ulong_var=500;
+select @@global.example_ulong_var;
+@@global.example_ulong_var
+500
+set global example_ulong_var=1111;
+ERROR 42000: Variable 'ulong_var' can't be set to the value of '1111'
+select @@global.example_ulong_var;
+@@global.example_ulong_var
+500
+set session sql_mode=@old_sql_mode;
+set session old=bla;
+ERROR HY000: Variable 'old' is a read only variable
+UNINSTALL PLUGIN example;