#!/bin/sh -e

RUNDIR=$(udevadm info --run || exit 0)

[ -d $RUNDIR ] || exit 0
mkdir -p $RUNDIR/rules.d/

[ ! -e $RUNDIR/rules.d/61-dev-root-link.rules ] || exit 0

eval $(udevadm info --export --export-prefix=ROOT_ --device-id-of-file=/ || true)

[ "$ROOT_MAJOR" -a "$ROOT_MINOR" ] || exit 0

# btrfs filesystems have bogus major/minor numbers
[ "$ROOT_MAJOR" != 0 ] || exit 0

echo 'ACTION=="add|change", SUBSYSTEM=="block", ENV{MAJOR}=="'$ROOT_MAJOR'", ENV{MINOR}=="'$ROOT_MINOR'", SYMLINK+="root"' \
    > $RUNDIR/root-link-rule
mv $RUNDIR/root-link-rule $RUNDIR/rules.d/61-dev-root-link.rules