On Sun, Nov 24, 2019 at 7:53 PM Jeffrey Walton <noloa...@gmail.com> wrote:
> On Sun, Nov 24, 2019 at 10:10 PM Philip Guenther <guent...@gmail.com> > wrote: > > > > On Sun, Nov 24, 2019 at 3:11 AM Jeffrey Walton <noloa...@gmail.com> > wrote: > >> > >> I am struggling to get a USB modem and terminal configured properly > >> under OpenBSD. The same code on Linux is fine. The symptom I am seeing > >> is a hung read() after issuing ATZ\r to the modem. > >> > >> I'm guessing there's an uninitialized field in my struct termios tty. > > > > I'm not sure what you mean by that. Do you mean you're concerned that > you're you making a tcsetattr(3) call on an incompletely initialized > structure? Or do you mean you're concerned that the initial configuration > of the tty provided by the kernel is in a "not good" state? > > I think cfmakeraw is not initializing the structure properly. It is an > intermittent failure. > This code is misusing cfmakeraw(3): it needs to call tcgetattr(3) on the tty fd and only call cfmakeraw() on the termios structure that tcgetattr() has filled in. (There may be other problems; I only reviewed enough to see that it was violating the rule I mentioned in my previous post. The _only_ portable way to initialize a struct termios is to use tcgetattr()!) Philip Guenther
