#!/bin/bash
#
# Create a "bank" of tap network devices that can be used by the
# runqemu script. This script needs to be run as root, and will
# use the tunctl binary from the build system sysroot. Note: many Linux 
# distros these days still use an older version of tunctl which does not
# support the group permissions option, hence the need to use the build
# system provided version.
#
# Copyright (C) 2010 Intel Corp.
#
# SPDX-License-Identifier: GPL-2.0-only
#

uid=`id -u`
gid=`id -g`
if [ -n "$SUDO_UID" ]; then
    uid=$SUDO_UID
fi
if [ -n "$SUDO_GID" ]; then
    gid=$SUDO_GID
fi

usage() {
	echo "Usage: sudo $0 <uid> <gid> <num> <staging_bindir_native>"
	echo "Where <uid> is the numeric user id the tap devices will be owned by"
	echo "Where <gid> is the numeric group id the tap devices will be owned by"
	echo "<num> is the number of tap devices to create (0 to remove all)"
	echo "<native-sysroot-basedir> is the path to the build system's native sysroot"
	echo "For example:"
	echo "$ bitbake qemu-helper-native"
	echo "$ sudo $0 $uid $gid 4 tmp/sysroots-components/x86_64/qemu-helper-native/usr/bin"
	echo ""
	exit 1
}

if [ $# -ne 4 ]; then
	echo "Error: Incorrect number of arguments"
	usage
fi

TUID=$1
GID=$2
COUNT=$3
STAGING_BINDIR_NATIVE=$4

# check if COUNT is a number and >= 0
if ! [ $COUNT -ge 0 ]; then
	echo "Error: Incorrect count: $COUNT"
	exit 1
fi

if [ $EUID -ne 0 ]; then
	echo "Error: This script must be run with root privileges"
	exit
fi

SCRIPT_DIR=`dirname $0`
RUNQEMU_IFUP="$SCRIPT_DIR/runqemu-ifup"
if [ ! -x "$RUNQEMU_IFUP" ]; then
	echo "Error: Unable to find the runqemu-ifup script in $SCRIPT_DIR"
	exit 1
fi

TUNCTL=$STAGING_BINDIR_NATIVE/tunctl
ip_supports_tuntap=false
if interfaces=`ip tuntap list` 2>/dev/null; then
	ip_supports_tuntap=true
	interfaces=`echo "$interfaces |cut -f1 -d:`
elif [[ ! -x "$TUNCTL" || -d "$TUNCTL" ]]; then
	echo "Error: $TUNCTL is not an executable"
	usage
elif interfaces=`ip link` 2>/dev/null; then
	interfaces=`echo "$interfaces" | sed '/^[0-9]\+: \(docker[0-9]\+\):.*/!d; s//\1/'`
else
	echo "Failed to call 'ip link'" >&2
	exit 1
fi

# Ensure we start with a clean slate
for tap in $interfaces; do
	echo "Note: Destroying pre-existing tap interface $tap..."
	if $ip_supports_tuntap; then
		ip tuntap del $tap mode tap
	else
		$TUNCTL -d $tap
	fi
done
rm -f /etc/runqemu-nosudo

if [ $COUNT -eq 0 ]; then
	exit 0
fi

echo "Creating $COUNT tap devices for UID: $TUID GID: $GID..."
for ((index=0; index < $COUNT; index++)); do
	echo "Creating tap$index"
	if ! ifup=`$RUNQEMU_IFUP $TUID $GID $STAGING_BINDIR_NATIVE 2>&1`; then
		echo "Error running tunctl: $ifup"
		exit 1
	fi
done

echo "Note: For systems running NetworkManager, it's recommended"
echo "Note: that the tap devices be set as unmanaged in the"
echo "Note: NetworkManager.conf file. Add the following lines to"
echo "Note: /etc/NetworkManager/NetworkManager.conf"
echo "[keyfile]"
echo "unmanaged-devices=interface-name:tap*"

# The runqemu script will check for this file, and if it exists,
# will use the existing bank of tap devices without creating
# additional ones via sudo.
touch /etc/runqemu-nosudo