Method handleErrorPacket

packets.go:588–629

Error Packet https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_basic_err_packet.html

(data []byte)

// Error Packet
// https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_basic_err_packet.html
func (mc *mysqlConn) handleErrorPacket(data []byte) error {
	if data[0] != iERR {
		return ErrMalformPkt
	}

	// 0xff [1 byte]

	// Error Number [16 bit uint]
	errno := binary.LittleEndian.Uint16(data[1:3])

	// 1792: ER_CANT_EXECUTE_IN_READ_ONLY_TRANSACTION
	// 1290: ER_OPTION_PREVENTS_STATEMENT (returned by Aurora during failover)
	// 1836: ER_READ_ONLY_MODE
	if (errno == 1792 || errno == 1290 || errno == 1836) && mc.cfg.RejectReadOnly {
		// Oops; we are connected to a read-only connection, and won't be able
		// to issue any write statements. Since RejectReadOnly is configured,
		// we throw away this connection hoping this one would have write
		// permission. This is specifically for a possible race condition
		// during failover (e.g. on AWS Aurora). See README.md for more.
		//
		// We explicitly close the connection before returning
		// driver.ErrBadConn to ensure that `database/sql` purges this
		// connection and initiates a new one for next statement next time.
		mc.Close()
		return driver.ErrBadConn
	}

	me := &MySQLError{Number: errno}

	pos := 3

	// SQL State [optional: # + 5bytes string]
	if data[3] == 0x23 {
		copy(me.SQLState[:], data[4:4+5])
		pos = 9
	}

	// Error Message [string]
	me.Message = string(data[pos:])

	return me
}

func readStatus(b []byte) statusFlag {
	return statusFlag(b[0]) | statusFlag(b[1])<<8