trans/checkperms.c: add deferred authorization translator

Setup the translator:

    echo HELLOWORLD > /hello && \
    settrans -cga /hello $(realpath ~/Dev/hurd/trans/checkperms) --groupname=user

Create the FIFOs:

    USER=root
    GROUP=user
    mkdir -p /run/$USER/request-permission
    mkdir -p /run/$USER/grant-permission
    mkfifo /run/$USER/request-permission/$GROUP
    mkfifo /run/$USER/grant-permission/$GROUP

Setup the permission-granting program in a separate shell:

    USER=root
    GROUP=user
    while true; do
      PID="$(cat /run/$USER/request-permission/$GROUP)"
      echo Process $PID tries to access file /hello but is not in the required group $GROUP.
      ps-hurd -p $PID -aeux
      if [[ "$(read -e -p 'Grant permission and add group "'$GROUP'" for 5 minutes? [y/N]> '; echo $REPLY)" == [Yy]* ]]; then
        addauth -p $PID -g $GROUP
        echo 0 > /run/$USER/grant-permission/$GROUP
        (sleep 300 && rmauth -p $PID -g $GROUP 2>/dev/null) &
      else
        echo 1 > /run/$USER/grant-permission/$GROUP
      fi
    done

Access the translator as user without the required group and with the group:

    su - user --shell /bin/bash -c 'cat /hello'
    cat /hello & # accept the request in the permission granting program

0 files changed, 0 insertions, 0 deletions