MDEV-27013: COM_STMT_PREPARE returns 0 columns for INSERT .. RETURNING

If this was a SELECT statement, the columns would be populated
by the mysql_test_insert call to send_prep_stmt. So we need to
get the column count for returning statements and populate this
instead of 0.

Note the unit test would return the correct results the server
correction changed as it was popluated from the COM_STMT_EXECUTE.

However this test useful to run via socat interceptor[1] to examine the
results at offset 9 after packet beginning 0c.

tests/mariadb-client-test -S /tmp/intercept.sock  -u $USER -D test  test_mdev_27013

[1] socat -x -v UNIX-LISTEN:/tmp/intercept.sock,fork
UNIX-CONNECT:/tmp/mariadb.sock

Author: grooverdan

sql/sql_prepare.cc

@@ -2434,6 +2434,7 @@ static bool check_prepared_statement(Prepared_statement *stmt)
   TABLE_LIST *tables;
   enum enum_sql_command sql_command= lex->sql_command;
   int res= 0;
+  bool returning= false;
   DBUG_ENTER("check_prepared_statement");
   DBUG_PRINT("enter",("command: %d  param_count: %u",
                       sql_command, stmt->param_count));
@@ -2495,6 +2496,7 @@ static bool check_prepared_statement(Prepared_statement *stmt)
                            lex->many_values,
                            lex->update_list, lex->value_list,
                            lex->duplicates);
+    returning= lex->has_returning();
     break;
 
   case SQLCOM_LOAD:
@@ -2516,6 +2518,7 @@ static bool check_prepared_statement(Prepared_statement *stmt)
 
   case SQLCOM_DELETE:
     res= mysql_test_delete(stmt, tables);
+    returning= lex->has_returning();
     break;
   /* The following allow WHERE clause, so they must be tested like SELECT */
   case SQLCOM_SHOW_DATABASES:
@@ -2655,11 +2658,13 @@ static bool check_prepared_statement(Prepared_statement *stmt)
 
   case SQLCOM_DELETE_MULTI:
     res= mysql_test_multidelete(stmt, tables);
+    returning= lex->has_returning();
     break;
 
   case SQLCOM_INSERT_SELECT:
   case SQLCOM_REPLACE_SELECT:
     res= mysql_test_insert_select(stmt, tables);
+    returning= lex->has_returning();
     break;
 
   case SQLCOM_HA_READ:
@@ -2725,7 +2730,17 @@ static bool check_prepared_statement(Prepared_statement *stmt)
                                                     Protocol::SEND_EOF);
        }
        else
-         res= send_prep_stmt(stmt, 0);
+       {
+	 if (returning)
+	 {
+           select_send result(thd);
+           List<Item> &field_list= lex->returning()->item_list;
+           res= send_prep_stmt(stmt, field_list.elements) ||
+                result.send_result_set_metadata(field_list, Protocol::SEND_EOF);
+	 }
+	 else
+           res= send_prep_stmt(stmt, 0);
+       }
        if (!res)
          thd->protocol->flush();
     }

tests/mysql_client_test.c

@@ -347,7 +347,7 @@ static void test_prepare_insert_update()
   const char **cur_query;
 
   myheader("test_prepare_insert_update");
-  
+
   for (cur_query= testcase; *cur_query; cur_query++)
   {
     char query[MAX_TEST_QUERY_LENGTH];
@@ -21874,6 +21874,69 @@ static void test_mdev19838()
   myquery(rc);
 }
 
+static void test_mdev_27013()
+{
+  int rc;
+  unsigned paramCount = 1;
+  MYSQL_STMT *stmt;
+  MYSQL_FIELD *fld;
+  const char *commands[] = {
+    "SELECT * FROM mdev27013",
+    "SELECT c1,c2 FROM mdev27013",
+    "INSERT INTO mdev27013 (c1) VALUES('tweet') RETURNING *",
+    "REPLACE INTO mdev27013 SET c2='growl' RETURNING c1, c2",
+    "DELETE FROM mdev27013 RETURNING *"
+  };
+
+  myheader("test_mdev27013");
+
+  rc = mysql_query(mysql, "CREATE TABLE mdev27013("
+          "c1  char(36), c2 char(36)"
+    ")");
+  myquery(rc);
+
+  stmt = mysql_stmt_init(mysql);
+  check_stmt(stmt);
+
+  for (int com= 0; com < 5; com++)
+  {
+    rc = mariadb_stmt_execute_direct(stmt, commands[com], -1);
+
+    if (rc)
+      mct_log("comm: %s err: %s", commands[com], mysql_stmt_error(stmt));
+    DIE_UNLESS(rc == 0);
+
+    paramCount = mysql_stmt_field_count(stmt);
+    DIE_UNLESS(paramCount == 2);
+
+    fld= mariadb_stmt_fetch_fields(stmt);
+    DIE_UNLESS(fld != NULL);
+
+    mct_log("comm: %s\n", commands[com]);
+    for (unsigned int i = 0; i < paramCount; ++i)
+    {
+      mct_log("name: '%s'/'%s'; table: '%s'/'%s'; "
+              "db: '%s'; catalog: '%s'; length: %d; max_length: %d; "
+              "type: %d; decimals: %d\n",
+              (const char *) fld[i].name,
+              (const char *) fld[i].org_name,
+              (const char *) fld[i].table,
+              (const char *) fld[i].org_table,
+              (const char *) fld[i].db,
+              (const char *) fld[i].catalog,
+              (int) fld[i].length,
+              (int) fld[i].max_length,
+              (int) fld[i].type,
+              (int) fld[i].decimals);
+    }
+  }
+
+  mysql_stmt_close(stmt);
+
+  rc = mysql_query(mysql, "drop table mdev27013");
+  myquery(rc);
+}
+
 static void test_mdev_24411()
 {
   int        rc;
@@ -23274,6 +23337,7 @@ static struct my_tests_st my_tests[]= {
   { "test_mdev_34718_ad", test_mdev_34718_ad },
   { "test_mdev_34958", test_mdev_34958 },
   { "test_mdev_32086", test_mdev_32086 },
+  { "test_mdev_27013", test_mdev_27013 },
 #endif
   { 0, 0 }
 };