left side of pipe

[Pascal]

hi everybody,

I am trying to set up a graphical interface to the command line tool
ewfacquire (https://github.com/libyal/libewf) with the graphical tool yad (
https://github.com/v1cont/yad).
here is roughly the bash script used :

set -o pipefail
ewfacquier -t /tmp/test /dev/sda1 |
yad --progress --progress-text "copying..." --pulsate --auto-close
--auto-kill --button=Cancel:252
if [ $? -eq 0 ]
then
    yad --text="OK:-)" --button=Return --image=emblem-default
else
    yad --text="KO:-(" --button=Cancel --image=emblem-noread
fi

it works fine as long as I don't stop yad.
if I stop yad, the ewfacquire process continues to run for a few more
(long) seconds even though the script is finished.
how to stop ewfacquire when canceling yad (while keeping the pipe exit code
in the opposite case for the if test) ?

regards, lacsaP.