Return error in resultset , #750

Depending from the query, an error "Query execution was interrupted" can be returned either as:
* a standalone ERR Packet (previously handled)
* an ERR Packet at the end of a result set : this commit handle this case

include/MySQL_Protocol.h

@@ -52,6 +52,7 @@ class MySQL_ResultSet {
 	unsigned int add_row(MYSQL_ROW row);
 	unsigned int add_row2(MYSQL_ROWS *row, unsigned char *offset);
 	void add_eof();
+	void add_err(MySQL_Data_Stream *_myds);
 	bool get_resultset(PtrSizeArray *PSarrayFinal);
 	unsigned char *buffer;
 	unsigned int buffer_used;

lib/MySQL_Protocol.cpp

@@ -1885,6 +1885,25 @@ void MySQL_ResultSet::add_eof() {
 	resultset_completed=true;
 }
 
+void MySQL_ResultSet::add_err(MySQL_Data_Stream *_myds) {
+	PtrSize_t pkt;
+	if (myprot) {
+		MYSQL *_mysql=_myds->myconn->mysql;
+		buffer_to_PSarrayOut();
+		char sqlstate[10];
+		sprintf(sqlstate,"%s",mysql_sqlstate(_mysql));
+		if (_myds && _myds->killed_at) { // see case #750
+			myprot->generate_pkt_ERR(false,&pkt.ptr,&pkt.size,sid,1907,sqlstate,"Query execution was interrupted, query_timeout exceeded");
+		} else {
+			myprot->generate_pkt_ERR(false,&pkt.ptr,&pkt.size,sid,mysql_errno(_mysql),sqlstate,mysql_error(_mysql));
+		}
+		PSarrayOUT->add(pkt.ptr,pkt.size);
+		sid++;
+		resultset_size+=pkt.size;
+	}
+	resultset_completed=true;
+}
+
 bool MySQL_ResultSet::get_resultset(PtrSizeArray *PSarrayFinal) {
 	transfer_started=true;
 	if (myprot) {

lib/mysql_connection.cpp

@@ -899,6 +899,16 @@ handler_again:
 						NEXT_IMMEDIATE(ASYNC_USE_RESULT_CONT); // we continue looping
 					}
 				} else {
+					if (mysql) {
+						int _myerrno=mysql_errno(mysql);
+						if (_myerrno) {
+							if (myds) {
+								MyRS->add_err(myds);
+								NEXT_IMMEDIATE(ASYNC_QUERY_END);
+							}
+						}
+					}
+					// we reach here if there was no error
 					MyRS->add_eof();
 					NEXT_IMMEDIATE(ASYNC_QUERY_END);
 				}