How to make the read function not to hang?

Question

I'm using socat to create a virtual serial port with:

socat PTY,link=/dev/ttySV0,echo=1 PTY,link=/dev/ttySV1,echo=1

The in my program written in C++, I open the ttySV1 port and start to read.

The read function is in a while, but the problem is that the read function hangs until I send data to the port. Do you know how to make the taht function not to hang and just exit if there is no data in the buffer?

EDIT: I send data to the port using:

echo [data] > /dev/ttySV0

Answer 1

You could also use a system read function depending on the operating system you are running. The details should be under man (3) read.

You would have to set O_NONBLOCK using fnctl. This should cause your read to fail if the pipe / FIFO is currently empty. I checked the man pages for Linux but their should be similar behaviors in most POSIX based systems.