#!/bin/sh

case $1 in
    prereqs)
        exit 0
        ;;
esac

set -e

# Extract kernel parameters
set -- $(cat /proc/cmdline)
items=""
for x in "$@"; do
    case "$x" in
        Aboot=*)
            aboot_flag="${x#Aboot=}"
            ;;
        net_*)
            item="${x#net_}"
            items="$items $item"
            ;;
        platform=*)
            platform_flag="${x#platform=}"
            ;;
    esac
done

random() {
    echo $(od -vAn -N1 -tu1 < /dev/urandom)
}

arista_net_devname() {
    local pciaddr="$1"
    local devname_prefix="$2"
    for path in $(ls -d /sys/class/net/${devname_prefix}* 2>/dev/null); do
        local devid="$(realpath "$path/device")"
        if echo "$devid" | grep -q "$pciaddr"; then
            echo "${path##*/}"
            return
        fi
    done
}

arista_net_rename() {
    local device_path="$1"
    local new_name="$2"
    local from_name="$3"
    devname=$(arista_net_devname "$device_path" "$from_name")
    if [ -n "$devname" ]; then
        ip link set "$devname" name "$new_name"
    fi
}

# Sets the MAC address to the value passed by Aboot through /proc/cmdline
tg3fixhwaddr()
{
    local default_tg3_hwaddr="00:10:18:00:00:00"
    local pciaddr="$1"
    local hwaddr="$2"

    devname=$(arista_net_devname "$pciaddr")
    if [ -z "$devname" ]; then
        return
    fi

    driver=$(basename $(readlink "/sys/class/net/$devname/device/driver"))
    if [ "$driver" != "tg3" ]; then
        return 0
    fi

    if [ "$hwaddr" = "$default_tg3_hwaddr" ]; then
        hwaddr=$(cat /sys/class/net/$devname/address)
    fi

    if [ "$hwaddr" = "$default_tg3_hwaddr" ]; then
        hwaddr=$(printf "%02x" "$(($(random) & 0xfe | 0x02))")
        for i in 1 2 3 4 5; do
            hwaddr=$(printf "$hwaddr:%02x" "$(($(random) & 0xfe | 0x02))")
        done
    fi

    ip link set dev "$devname" addr "$hwaddr"
}

if [ -n "$aboot_flag" ]; then
    for item in $items; do
        key="${item%=*}"
        value="${item#*=}"
        hwaddr=$(eval echo \${hwaddr_${key}})
        if [ -n "$hwaddr" ]; then
            tg3fixhwaddr "$value" "$hwaddr"
        fi
    done
fi

# Iterate over all the net_maX items found in the cmdline two times.
# First time renaming the interfaces to maX.
# The second time renaming them to their final name ethX.
if [ -n "$aboot_flag" -a "$platform_flag" == 'rook' ]; then
    for item in $items; do
        key="${item%=*}"
        value="${item#*=}"
        arista_net_rename "$value" "$key" eth
    done
    for item in $items; do
        key="${item%=*}"
        value="${item#*=}"
        index="${key#ma}"
        index="$(( $index - 1 ))"
        newKey="eth$index"
        arista_net_rename "$value" "$newKey" ma
    done
fi