Share data between host and guest with QEMU

Question

I have a Centos7 host on wich i emulate a Concurrent-DOS guest with QEMU, and i have to share data between the two environnements. I am actually using FTP to send file to and from each other, but it is not fast enough for my needs. I would like to know if it is possible to either create a pipe or block-device to send binary data from each side, or if not to share a directory between the two so that if i create a file in it it is visible instantly from the other environnement.

I am new with QEMU, and there are few examples but my issue here is to make it work with a old system like DOS. The data i have to share is actually just a data structure, wich i actually write in a file opened in binary mode before to send it via ftp.

Thanks for the help !