MXS-1808: Only store SQL statements for retrying

Only commands that can contain an SQL statements should be stored for
retrying (COM_QUERY and COM_EXECUTE). Other commands are either session
commands or do not work with query retrying.

maxscale-system-test/CMakeLists.txt

@@ -648,6 +648,10 @@ add_test_executable(mxs1786_statistics.cpp mxs1786_statistics replication LABELS
 # https://jira.mariadb.org/browse/MXS-1787
 add_test_executable(mxs1787_call_ps.cpp mxs1787_call_ps replication LABELS readwritesplit REPL_BACKEND)
 
+# MXS-1808: Crash with mysql_stmt_send_long_data
+# https://jira.mariadb.org/browse/MXS-1808
+add_test_executable(mxs1808_long_data.cpp mxs1808_long_data replication LABELS readwritesplit REPL_BACKEND)
+
 # 'namedserverfilter' test
 add_test_executable(namedserverfilter.cpp namedserverfilter namedserverfilter LABELS namedserverfilter LIGHT REPL_BACKEND)
 

maxscale-system-test/mxs1808_long_data.cpp

@@ -0,0 +1,86 @@
+#include "testconnections.h"
+#include <iostream>
+
+using namespace std;
+
+void print_stmt_error(MYSQL_STMT *stmt, const char* msg)
+{
+    cout << "Error: " << msg << ": " << mysql_stmt_error(stmt) << endl;
+}
+
+static int test_long_data(MYSQL *conn, int sqlsize)
+{
+    int data1size = sqlsize / 2;
+
+    char * data1 = (char*) malloc(data1size);
+    memset(data1, 97, data1size);
+    char * data3 = (char*) malloc(sqlsize);
+    memset(data3, 99, sqlsize);
+
+    MYSQL_STMT *stmt;
+    stmt = mysql_stmt_init(conn);
+    int        rc, int_data;
+    MYSQL_RES  *result;
+    MYSQL_BIND my_bind[1];
+
+    rc = mysql_autocommit(conn, 1);
+
+    if (NULL == stmt)
+    {
+        fprintf(stderr, "%s", mysql_error(conn));
+        return 0;
+    }
+    if (mysql_stmt_prepare(stmt, "select ?", strlen("select ?")) != 0)
+    {
+        print_stmt_error(stmt, "stmt prepare fail");
+        return 0;
+    }
+
+    memset((char*) my_bind, 0, sizeof(my_bind));
+
+    my_bind[0].buffer = (void *)&int_data;
+    my_bind[0].buffer_type = MYSQL_TYPE_STRING;
+
+    if (mysql_stmt_bind_param(stmt, my_bind) != 0)
+    {
+        print_stmt_error(stmt, "bind param error");
+        return 0;
+    }
+
+    /* supply data in pieces */
+    if (mysql_stmt_send_long_data(stmt, 0, data1, data1size) != 0)
+    {
+        print_stmt_error(stmt, "send long data1 failed");
+        return 0;
+    }
+    if (mysql_stmt_send_long_data(stmt, 0, data3, sqlsize) != 0)
+    {
+        print_stmt_error(stmt, "send long data3 failed");
+        return 0;
+    }
+
+    /* execute */
+    if (mysql_stmt_execute(stmt) != 0)
+    {
+        print_stmt_error(stmt, "execute prepare stmt failed");
+        return 0;
+    }
+    /* get the result */
+    result = mysql_store_result(conn);
+    mysql_free_result(result);
+    mysql_stmt_close(stmt);
+    free(data1);
+    free(data3);
+    return 1;
+}
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+
+    test.maxscales->connect();
+    test.assert(test_long_data(test.maxscales->conn_rwsplit[0], 123456), "Test should work");
+    test.maxscales->disconnect();
+
+    return test.global_result;
+}

server/modules/routing/readwritesplit/rwsplit_route_stmt.cc

@@ -242,7 +242,13 @@ bool route_single_stmt(RWSplit *inst, RWSplitSession *rses, GWBUF *querybuf, con
             if ((target = handle_slave_is_target(inst, rses, command, stmt_id)))
             {
                 succp = true;
-                store_stmt = rses->rses_config.retry_failed_reads;
+
+                if (rses->rses_config.retry_failed_reads &&
+                    (command == MXS_COM_QUERY || command == MXS_COM_STMT_EXECUTE))
+                {
+                    // Only commands that can contain an SQL statement should be stored
+                    store_stmt = true;
+                }
             }
         }
         else if (TARGET_IS_MASTER(route_target))