#!/usr/bin/env bash
# SPDX-License-Identifier: LGPL-2.1-or-later

set -eu
set -o pipefail

root="${1:?Usage: $0 container-root}"
mkdir -p "$root"
mkdir -p "$root/usr/bin"

# On openSUSE the static linked version of busybox is named "busybox-static".
busybox="$(type -P busybox-static || type -P busybox)"
cp "$busybox" "$root/usr/bin/busybox"

mkdir "$root/var"
mkdir -p "$root/usr/lib"
touch "$root/usr/lib/os-release"

ln -s busybox "$root/usr/bin/cat"
ln -s busybox "$root/usr/bin/hostname"
ln -s busybox "$root/usr/bin/ip"
ln -s busybox "$root/usr/bin/md5sum"
ln -s busybox "$root/usr/bin/mountpoint"
ln -s busybox "$root/usr/bin/ps"
ln -s busybox "$root/usr/bin/seq"
ln -s busybox "$root/usr/bin/sh"
ln -s busybox "$root/usr/bin/sleep"
ln -s busybox "$root/usr/bin/stat"
ln -s busybox "$root/usr/bin/test"
ln -s busybox "$root/usr/bin/touch"
ln -s busybox "$root/usr/bin/tr"
ln -s busybox "$root/usr/bin/true"
ln -s busybox "$root/usr/bin/usleep"

# Mock the bare minimum of getent to make systemd-nspawn --user= "work"
cat >"$root/usr/bin/getent" <<\EOF
#!/bin/sh

if [[ $# - eq 0 ]]; then
    :
elif [[ $1 == passwd ]]; then
    echo "testuser:x:1000:1000:testuser:/:/bin/sh"
elif [[ $1 == initgroups ]]; then
    echo "testuser"
fi
EOF
chmod +x "$root/usr/bin/getent"

mkdir -p "$root/usr/sbin"
cat >"$root/usr/sbin/init" <<\EOF
#!/bin/sh

printf "ps aufx:\n"
ps aufx

printf "/proc/1/cmdline:\n"
printf "%s\n\n" "$(tr '\0' ' ' </proc/1/cmdline)"

printf "/proc/1/environ:\n"
printf "%s\n\n" "$(tr '\0' '\n' </proc/1/environ)"

printf "/proc/1/mountinfo:\n"
cat /proc/self/mountinfo
printf "\n"

printf "/proc/1/cgroup:\n"
printf "%s\n\n" "$(cat /proc/1/cgroup)"

printf "/proc/1/uid_map:\n"
printf "%s\n\n" "$(cat /proc/1/uid_map)"

printf "/proc/1/setgroups:\n"
printf "%s\n\n" "$(cat /proc/1/setgroups)"

printf "/proc/1/gid_map:\n"
printf "%s\n\n" "$(cat /proc/1/gid_map)"

printf "ip link:\n"
ip link
EOF
chmod +x "$root/usr/sbin/init"

ln -srf "$root/usr/bin" "$root/bin"
ln -srf "$root/usr/sbin" "$root/sbin"
ln -srf "$root/usr/lib" "$root/lib"