I am trying to integrate Windows based system with OSR 5.0.7, where
Windows system is supposed to send me data in real time. For some
reason Windows developers would not use tcp/ip socket, as asked, but
insist on sending their data to a daily file, which we have to read and
maintain current position within the file.

If the Windows file resided on Samba share, I could use:

pfd = popen("tail -f file_name", "r")
while(fgets( ... pfd )

to simulate real time data exchange.

I'd like to ask for your opinion on this solution, whether it would be
stable, any possible issues, such as buffering, etc.

It is going to be under 10,000 readings per day to be sent to Unix,
delay of 2 - 3 seconds are tolerated.

Any suggestions are welcome.