#!/bin/bash -e
#
# This script is run to rename virtual interfaces
#

if [ -n "$UDEV_LOG" ]; then
	if [ "$UDEV_LOG" -ge 7 ]; then
		set -x
	fi
fi

# according to dev_new_index(), ifindex is within [1, INT_MAX]
int_max=$(/usr/bin/getconf INT_MAX)
ifindex_before() {
	a=$1
	b=$2

	((0 < (b - a) && (b - a) < int_max / 2 ||
		-1 * int_max < (b - a) && (b - a) < -1 * int_max / 2))
}

rename_interface() {
	local src_net=$1
	local dest_net=$2
	local err=0

	/sbin/ip link set dev $src_net down
	/sbin/ip link set dev $src_net name $dest_net
}

if [ -z "$INTERFACE" ]; then
	echo "missing \$INTERFACE" >&2
	exit 1
fi

if [ -e "/sys/class/net/$INTERFACE/device/physfn" ]; then
	pf=$(ls -1 "/sys/class/net/$INTERFACE/device/physfn/net")
	if [ $(echo "$pf" | wc -l) -ne 1 ]; then
		echo "too many pf's" >&2
		exit 1
	fi
	read vfindex < "/sys/class/net/$INTERFACE/ifindex"
	read pfindex < "/sys/class/net/$pf/ifindex"
	if ifindex_before $pfindex $vfindex; then
		bus_info=$(basename $(readlink "/sys/class/net/$INTERFACE/device"))
		for virtfn in "/sys/class/net/$pf/device/"virtfn*; do
			if [ "$(basename $(readlink "$virtfn"))" = "$bus_info" ]; then
				vfnum=$(basename "$virtfn")
				vfnum=${vfnum#virtfn}
				echo "INTERFACE_NEW=$pf.vf$vfnum"
				exit 0
			fi
		done
	fi
fi

read pfindex < "/sys/class/net/$INTERFACE/ifindex"
shopt -s nullglob
for virtfn in "/sys/class/net/$INTERFACE/device/"virtfn*; do
	vf=$(ls -1 "$virtfn/net")
	if [ $(echo "$vf" | wc -l) -ne 1 ]; then
		echo "too many vf's" >&2
		exit 1
	fi
	read vfindex < "/sys/class/net/$vf/ifindex"
	if ifindex_before $vfindex $pfindex; then
		vfnum=$(basename "$virtfn")
		vfnum=${vfnum#virtfn}
		if [ "$INTERFACE_NEW" ]; then
			new_name=$INTERFACE_NEW
		else
			new_name=$INTERFACE
		fi
		new_name="$new_name.vf$vfnum"
		if [ "$vf" != "$new_name" ]; then
			rename_interface "$vf" "$new_name"
		fi
	fi
done