In article <BsGKE1.Cp@Nyongwa.CAM.ORG> steve@Nyongwa.CAM.ORG (Steve M. Robbins) writes:
quoted text
>
>I have a program which reads in lines from a terminal using fgets().
>Normally this means I can use the backspace key for editing, and my program
>doesn't see this; it simply gets the edited line.
>
>Then, I wanted some daemons executed periodically, regardless of what the
>user is doing, so I used alarm().  All my SIGALRM handler does is call
>signal() and alarm() again.  Suddenly line-editing no longer works.
>
>That is, it works between alarms, but as soon as the signal hits, I can no 
>longer backspace over what is already in the buffer.

Sorry - it's a kernel bug that probably creapt in in 0.96c or so. Here
is a easy fix that should clear it up (I hope - untested as usual):

in linux/kernel/chr_drv/tty_io.c: function read_chan()

        else if (L_CANON(tty))
                wait_for_canon_input(tty);

should read:

        else if (L_CANON(tty)) {
                wait_for_canon_input(tty);
                if (current->signal & ~current->blocked)
                        return -ERESTARTSYS;
        }

The same bug exists in 0.97 (but no longer in my version).

I'd like to hear if the above clears up the problem.

                Linus