Cover a protocol design error for multi result statements

Error packet does not contain the server status, so client does not know if
there is another multi result or not. Luckily, an error always aborts
execution of a statement, so it is safe to expect that there is no result
statement and turn off the SERVER_MORE_RESULTS_EXISTS flag.

Applying this workaround for protocol error is needed after every failed
call which may produce multi result set and we already received some multi
result set. So after mysql_next_result() or after mysql_real_query() with
multi statements.

Author: pali

dbdimp.c

@@ -2662,6 +2662,11 @@ IV mariadb_db_do6(SV *dbh, imp_dbh_t *imp_dbh, SV *statement_sv, SV *attribs, I3
 
   if (next_result_rc > 0)
   {
+#if MYSQL_VERSION_ID < 50025
+    /* Cover a protocol design error: error packet does not contain the server status.
+     * Luckily, an error always aborts execution of a statement, so it is safe to turn off the flag. */
+    imp_dbh->pmysql->server_status &= ~SERVER_MORE_RESULTS_EXISTS;
+#endif
     /* This is error for previous unfetched result ret. So do not report server errors to caller which is expecting new result set. */
     error = mysql_errno(imp_dbh->pmysql);
     if (error == CR_COMMANDS_OUT_OF_SYNC || error == CR_OUT_OF_MEMORY || error == CR_SERVER_GONE_ERROR || error == CR_SERVER_LOST || error == CR_UNKNOWN_ERROR)
@@ -2841,6 +2846,12 @@ IV mariadb_db_do6(SV *dbh, imp_dbh_t *imp_dbh, SV *statement_sv, SV *attribs, I3
 
     if (next_result_rc > 0)
     {
+#if MYSQL_VERSION_ID < 50025
+      /* Cover a protocol design error: error packet does not contain the server status.
+       * Luckily, an error always aborts execution of a statement, so it is safe to turn off the flag. */
+      imp_dbh->pmysql->server_status &= ~SERVER_MORE_RESULTS_EXISTS;
+#endif
+
       if (DBIc_DBISTATE(imp_dbh)->debug >= 2)
         PerlIO_printf(DBIc_LOGPIO(imp_dbh), "\t<- do() ERROR: %s\n", mysql_error(imp_dbh->pmysql));
 
@@ -4021,6 +4032,12 @@ static bool mariadb_st_free_result_sets(SV *sth, imp_sth_t *imp_sth)
 
   if (next_result_rc > 0)
   {
+#if MYSQL_VERSION_ID < 50025
+    /* Cover a protocol design error: error packet does not contain the server status.
+     * Luckily, an error always aborts execution of a statement, so it is safe to turn off the flag. */
+    imp_dbh->pmysql->server_status &= ~SERVER_MORE_RESULTS_EXISTS;
+#endif
+
     if (DBIc_TRACE_LEVEL(imp_xxh) >= 2)
       PerlIO_printf(DBIc_LOGPIO(imp_xxh), "\t<- mariadb_st_free_result_sets: Error while processing multi-result set: %s\n",
                     mysql_error(imp_dbh->pmysql));
@@ -4118,6 +4135,11 @@ bool mariadb_st_more_results(SV* sth, imp_sth_t* imp_sth)
    */
   if (next_result_return_code > 0)
   {
+#if MYSQL_VERSION_ID < 50025
+    /* Cover a protocol design error: error packet does not contain the server status.
+     * Luckily, an error always aborts execution of a statement, so it is safe to turn off the flag. */
+    imp_dbh->pmysql->server_status &= ~SERVER_MORE_RESULTS_EXISTS;
+#endif
     mariadb_dr_do_error(sth, mysql_errno(imp_dbh->pmysql), mysql_error(imp_dbh->pmysql),
              mysql_sqlstate(imp_dbh->pmysql));
 
@@ -4305,6 +4327,11 @@ static my_ulonglong mariadb_st_internal_execute(
           (!mariadb_db_reconnect(h, NULL) ||
            (mysql_real_query(*svsock, sbuf, slen))))
       {
+#if MYSQL_VERSION_ID < 50025
+        /* Cover a protocol design error: error packet does not contain the server status.
+         * Luckily, an error always aborts execution of a statement, so it is safe to turn off the flag. */
+        (*svsock)->server_status &= ~SERVER_MORE_RESULTS_EXISTS;
+#endif
         rows = -1;
       } else {
           /** Store the result from the Query */