From 46751d4b81c0e423759be07ee1f7f9d15627c42c Mon Sep 17 00:00:00 2001
From: Monty <monty@mariadb.org>
Date: Fri, 3 May 2024 10:27:35 +0300
Subject: [PATCH] MDEV-34060 Unexpected behavior upon reading I_S.ALL_PLUGINS
 under limited tmp space.

---
 mysql-test/main/tmp_space_usage.result | 14 ++++++++
 mysql-test/main/tmp_space_usage.test   | 16 +++++++++
 sql/sql_select.cc                      |  5 ++-
 sql/sql_show.cc                        | 48 ++++++++++++++++++++++----
 4 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/mysql-test/main/tmp_space_usage.result b/mysql-test/main/tmp_space_usage.result
index 6ca102a1a37..d0d00687c34 100644
--- a/mysql-test/main/tmp_space_usage.result
+++ b/mysql-test/main/tmp_space_usage.result
@@ -199,4 +199,18 @@ set @@global.max_tmp_total_space_usage=@save_max_tmp_total_space_usage;
 SET max_tmp_session_space_usage= 64*1024;
 SELECT MIN(VARIABLE_VALUE) OVER (), NTILE(1) OVER (), MAX(VARIABLE_NAME) OVER () FROM information_schema.SESSION_STATUS;
 ERROR HY000: Local temporary space limit reached
+#
+# MDEV-34060 Unexpected behavior upon reading I_S.ALL_PLUGINS under
+# limited tmp space
+#
+connect c1, localhost, root,,;
+set @@binlog_format=row;
+CREATE OR REPLACE TABLE t1 (a DATETIME) ENGINE=MyISAM;
+INSERT INTO t1 SELECT NOW() FROM seq_1_to_6000;
+SET max_tmp_session_space_usage = 64*1024;
+SELECT * FROM information_schema.ALL_PLUGINS LIMIT 2;
+ERROR HY000: Local temporary space limit reached
+drop table t1;
+connection default;
+disconnect c1;
 # End of 11.5 tests
diff --git a/mysql-test/main/tmp_space_usage.test b/mysql-test/main/tmp_space_usage.test
index 581e9d13c7d..1f4de53d8eb 100644
--- a/mysql-test/main/tmp_space_usage.test
+++ b/mysql-test/main/tmp_space_usage.test
@@ -259,4 +259,20 @@ SET max_tmp_session_space_usage= 64*1024;
 --error 200
 SELECT MIN(VARIABLE_VALUE) OVER (), NTILE(1) OVER (), MAX(VARIABLE_NAME) OVER () FROM information_schema.SESSION_STATUS;
 
+--echo #
+--echo # MDEV-34060 Unexpected behavior upon reading I_S.ALL_PLUGINS under
+--echo # limited tmp space
+--echo #
+
+connect(c1, localhost, root,,);
+set @@binlog_format=row;
+CREATE OR REPLACE TABLE t1 (a DATETIME) ENGINE=MyISAM;
+INSERT INTO t1 SELECT NOW() FROM seq_1_to_6000;
+SET max_tmp_session_space_usage = 64*1024;
+--error 200
+SELECT * FROM information_schema.ALL_PLUGINS LIMIT 2;
+drop table t1;
+connection default;
+disconnect c1;
+
 --echo # End of 11.5 tests
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 07061eeac8c..c410ea2fe50 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -4972,7 +4972,10 @@ int JOIN::exec_inner()
 
   if ((this->select_lex->options & OPTION_SCHEMA_TABLE) &&
       get_schema_tables_result(this, PROCESSED_BY_JOIN_EXEC))
-    DBUG_RETURN(0);
+  {
+    error= thd->is_error();
+    DBUG_RETURN(error);
+  }
 
   if (select_options & SELECT_DESCRIBE)
   {
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index c7cc6217cb7..d10d4b0813b 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -345,11 +345,32 @@ int fill_plugins(THD *thd, TABLE_LIST *tables, COND *cond)
 }
 
 
+/* Ignore common errors from plugin load */
+
+class plugin_show_error_handler : public Internal_error_handler
+{
+public:
+  bool handle_condition(THD *thd,
+                        uint sql_errno,
+                        const char* sqlstate,
+                        Sql_condition::enum_warning_level *level,
+                        const char* msg,
+                        Sql_condition ** cond_hdl)
+  {
+    if (sql_errno == ER_CANT_FIND_DL_ENTRY)
+      return true;
+    return false;
+  }
+};
+
+
 int fill_all_plugins(THD *thd, TABLE_LIST *tables, COND *cond)
 {
   DBUG_ENTER("fill_all_plugins");
   TABLE *table= tables->table;
   LOOKUP_FIELD_VALUES lookup;
+  plugin_show_error_handler err_handler;
+  const char *wstr, *wend;
 
   if (get_lookup_field_values(thd, cond, true, tables, &lookup))
     DBUG_RETURN(0);
@@ -364,10 +385,16 @@ int fill_all_plugins(THD *thd, TABLE_LIST *tables, COND *cond)
     DBUG_RETURN(1);
   }
 
-  if (!lookup.db_value.str)
-    plugin_dl_foreach(thd, 0, show_plugins, table);
+  thd->push_internal_handler(&err_handler);
 
-  const char *wstr= lookup.db_value.str, *wend= wstr + lookup.db_value.length;
+  if (!lookup.db_value.str)
+  {
+    if (plugin_dl_foreach(thd, 0, show_plugins, table) && thd->is_error())
+      goto end;
+  }
+
+  wstr= lookup.db_value.str;
+  wend= wstr + lookup.db_value.length;
   for (size_t i=0; i < dirp->number_of_files; i++)
   {
     FILEINFO *file= dirp->dir_entry+i;
@@ -394,12 +421,14 @@ int fill_all_plugins(THD *thd, TABLE_LIST *tables, COND *cond)
       }
     }
 
-    plugin_dl_foreach(thd, &dl, show_plugins, table);
-    thd->clear_error();
+    if (plugin_dl_foreach(thd, &dl, show_plugins, table) && thd->is_error())
+      break;
   }
 
+end:
+  thd->pop_internal_handler();
   my_dirend(dirp);
-  DBUG_RETURN(0);
+  DBUG_RETURN(thd->is_error());
 }
 
 
@@ -4810,10 +4839,15 @@ fill_schema_table_by_open(THD *thd, MEM_ROOT *mem_root,
                && thd->get_stmt_da()->sql_errno() != ER_WRONG_OBJECT
                && thd->get_stmt_da()->sql_errno() != ER_NOT_SEQUENCE;
       if (!run)
+      {
         thd->clear_error();
+        result= false;
+      }
       else if (!ext_error_handling)
+      {
         convert_error_to_warning(thd);
-      result= false;
+        result= false;
+      }
     }
   }