### Description **Originally reported by migration: https://bugs.libssh.org/T2** I added callbacks for external io [sftp_proof.zip](/uploads/59f0c6dac87bc263a51119c41bdc6859/sftp_proof.zip) [sftp_proof.zip](/uploads/59f0c6dac87bc263a51119c41bdc6859/sftp_proof.zip)