#!/bin/sh -e
#
# This script is run if the interface (recognized by its MAC address) lacks
# a rule for persistent naming.
#
# If there is already a persistent rule with that interface name then the
# current interface needs to be renamed.
#
# If the interface needs to be renamed, a NAME=value pair will be printed
# on stdout to allow udev to IMPORT it. Then a rule for the MAC address and
# interface name is written.
#
# (C) 2006 Marco d'Itri <md@Linux.IT>
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation version 2 of the License.

RULES_FILE='/etc/udev/rules.d/70-persistent-net.rules'

. /lib/udev/rule_generator.functions

interface_name_taken() {
	local value="$(find_all_rules 'NAME=' $INTERFACE)"
	if [ "$value" ]; then
		return 0
	else
		return 1
	fi
}

find_next_available() {
	raw_find_next_available "$(find_all_rules 'NAME=' "$1")"
}

write_rule() {
	local match="$1"
	local name="$2"
	local comment="$3"

	{
	if [ "$PRINT_HEADER" ]; then
		PRINT_HEADER=
		echo "# This file was automatically generated by the $0"
		echo "# program run by the persistent-net-generator.rules rules file."
		echo "#"
		echo "# You can modify it, as long as you keep each rule on a single line."
	fi

	echo ""
	[ "$comment" ] && echo "# $comment"
	echo "SUBSYSTEM==\"net\", $match, NAME=\"$name\""
	} >> $RULES_FILE
}

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

if [ "$1" ]; then
    while [ "$*" ] ; do
	case $1 in
	    --mac)
		shift
		MAC_ADDR=$1
		shift
		;;
	    --driver)
		shift
		DRIVER=$1
		shift
		;;
	    --id)
		shift
		ID=$1
		shift
		;;
	    *)
		MAC_ADDR=$1
		shift
		;;
	esac
    done
else
    MAC_ADDR=$(sysread address)
fi

if [ -z "$DRIVER" ] && [ -z "$ID" ] ; then
    if [ -z "$MAC_ADDR" ]; then
	echo "No MAC address for $INTERFACE." >&2
	exit 1
    fi
    if [ "$MAC_ADDR" = "00:00:00:00:00:00" ]; then
	echo "NULL MAC address for $INTERFACE." >&2
	exit 1
    fi
fi

# Prevent concurrent processes from modifying the file at the same time.
lock_rules_file

# Check if the rules file is writeable.
choose_rules_file

# If a rule using the current name already exists then find a new name and
# report it to udev which will rename the interface.
basename=${INTERFACE%%[0-9]*}
if interface_name_taken; then
	INTERFACE="$basename$(find_next_available "$basename[0-9]*")"
	if [ ! -t 1 ]; then
		echo "INTERFACE_NEW=$INTERFACE"
	fi
fi

# the DRIVERS key is needed to not match bridges and VLAN sub-interfaces
if [ "$MAC_ADDR" ] ; then
    match="DRIVERS==\"?*\", ATTR{address}==\"$MAC_ADDR\""
else
    match="DRIVERS==\"$DRIVER\", KERNELS==\"$ID\""
fi
if [ $basename = "ath" -o $basename = "wlan" ]; then
	match="$match, ATTR{type}==\"1\"" # do not match the wifi* interfaces
fi

write_rule "$match" "$INTERFACE" "$COMMENT"

unlock_rules_file

exit 0