bug fix: infinite loop when tty disappears

When TTY disappears and there is at least one fd watcher, raw_getbyte() can
enter an infinite loop where it keeps calling poll() over and over again.

To reproduce, open a terminal, start zsh and type this:

  rm -f /tmp/fifo
  mkfifo /tmp/fifo
  exec 3<>/tmp/fifo
  do-nothing() {}
  zle -F 3 do-nothing

Then make TTY disappear. For example, kill the parent with `kill -9 $PPID`
and close the terminal window if it's still there. Observe that zsh is
consiming 100% CPU. Note that do-nothing() never gets called.

This patch makes the poll() loop in raw_getbyte() terminate when TTY is
signalling POLLHUP. This makes the behavior consistent with the case where
TTY disappears while no fd watchers are installed.

0 files changed, 0 insertions, 0 deletions