local line name=${tcp_by_fd[$1]}
if [[ -n $name ]]
then
  local TCP_INVALIDATE_ZLE
  if (( $# > 2 )); then
    zle -I
    ## debugging only
    # print "Flags on the play:" ${argv[3,-1]}
  else
    TCP_INVALIDATE_ZLE=1
  fi
  if ! tcp_read -d -u $1; then
    [[ -n $TCP_INVALIDATE_ZLE ]] && zle -I
    print "[TCP fd $1 (session $name) gone awol; removing from poll list]" >& 2
    zle -F $1
    return 1
  fi
  return 0
else
  zle -I
  # Handle fds not in the TCP set similarly.
  # This does the drain thing, to try and get as much data out as possible.
  if ! read line <&$1; then
    print "[Reading on $1 failed; removing from poll list]" >& 2
    zle -F $1
    return 1
  fi
  line="fd$1:$line"
  local newline
  while read -t newline <&$1; do
    line="${line}
fd$1:$newline"
  done
fi
print -r - $line