blue-merle/files/etc/init.d/volatile-client-macs

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#!/bin/sh /etc/rc.common
# MAC addresses of connected clients are stored in a sqlite database.
# Having the database seems to be necessary for the device to be working properly.
# We intent to have the device store the database in RAM rather than on flash.
# We replace the directory with a memory-backed tmpfs which is as volatile as we can make it.
# We want to run ahead of "gl-tertf" which, currently, has a prioprity of 60.
# We also want to run ahead of "gl_clients" which has 99.
START=59
STOP=99
start() {
tmpdir="$(mktemp -d)"
# We mount a tmpfs so that the client database will be stored in memory only
mount -t tmpfs / "$tmpdir"
cp -a /etc/oui-tertf/client.db "$tmpdir"
shred --force --remove /etc/oui-tertf/client.db || rm -f /etc/oui-tertf/client.db
# If this script runs multiple times, we accumulate mounts; we try to avoid having mounts over mounts, so we unmount any existing tmpfs
umount -t tmpfs -l /etc/oui-tertf
mount -t tmpfs / /etc/oui-tertf
cp -a "$tmpdir/client.db" /etc/oui-tertf/client.db
umount -t tmpfs -l "$tmpdir"
}
stop() {
shred /etc/oui-tertf/client.db || rm -f /etc/oui-tertf/client.db
}