Hi,

The following code in ptcwrite() in kern/tty_pty.c is supposed to prevent 
the tty input buffer overflow (for certain cases):

   612  if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 &&
   613     (tp->t_canq.c_cc > 0 || !(tp->t_iflag&ICANON))) {
   614          wakeup(TSA_HUP_OR_INPUT(tp));
   615          goto block;
   616  }

But the ICANON flag is set in tp->t_lflag and not tp->t_iflag. The ICRNL flag
in tp->t_iflag has the same value as the ICANON flag in tp->t_lflag (0x100).
This leads to input buffer overflow as soon as the ICRNL bit is set in 
tp->t_iflag, and there are more than 1024 characters that telnet/ssh wants 
to write to the pty.

I discovered this problem when using libreadline because it changes the 
terminal settings every time it is begins/finishes reading a line.

Has anyone else seen a similar problem ? I saw identical behavior on NetBSD
too. Please CC me as I am not on the mailing list.

thanks
Neel


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