Fix kissattach 'Device or resource busy'

[martinhpedersen]

Hi,

I got bit by the kissattach issue mentioned in the user guide on Debian Jessie. I though it was strange, because I've written a program, fldigiattach, that exposes a pty slave to kissattach. I never experienced the issue.

After some debugging I realized that the only real difference between fldigiattach and the code in kiss.c was that fldigiattach, which is written in Go, indirectly uses non-blocking IO syscalls. This got me thinking that maybe the blocking read from pt_master_fd was causing the "Device or resource busy" error seen by kissattach.

This fix resolves the issue by using select() to wait for data before reading from the master fd.

I've confirmed the fix on Debian Jessie.

[DwaineGarden]

Is this going to get pulled?

[wb2osz]

Thanks for the fix!

This is now in the "dev" branch which is the latest development (sometimes unstable) location. To get this version:

git pull; git checkout dev; make clean; make

It was tested on Ubuntu. If a few people could test it on other Linux variants, and all goes well, I will cherry pick it to the "master" branch which is now version 1.3 beta test.

[martinhpedersen]

Glad I could make a small contribution to this great project!

That missing FD_SET call was embarrasing though, hehe! I should have at least caught it while testing the patch, but I mixed up read/write and ended up testing the master_fd writes instead of the modified read/select.

Anyway, I have tested current dev (ccae752) on my RPi 2 running Raspbian Jessie. I've made several connects (wl2k/FBB) using Linux AX 25 without any problems. Kissattach seems happy with the fix on Raspbian :)

73 de LA5NTA