#!/bin/sh
set -eu
export LC_ALL=C.UTF-8
export SOURCE_DATE_EPOCH={{ SOURCE_DATE_EPOCH }}

prefix=
if [ "$(id -u)" -eq 0 ] && [ "{{ MODE }}" != "root" ] && [ "{{ MODE }}" != "auto" ]; then
	if ! id "${SUDO_USER:-user}" >/dev/null 2>&1; then
		if [ ! -e /mmdebstrap-testenv ]; then
			echo "this test modifies the system and should only be run inside a container" >&2
			exit 1
		fi
		useradd --home-dir "/home/${SUDO_USER:-user}" --create-home "${SUDO_USER:-user}"
	fi
	prefix="runuser -u ${SUDO_USER:-user} --"
fi

# debootstrap uses apt-config to figure out whether the system running it has
# any proxies configured and then runs the binary to set the http_proxy
# environment variable. This will fail if debootstrap is run in a linux user
# namespace because auto-apt-proxy will see /tmp/.auto-apt-proxy-0 as being
# owned by the user "nobody" and group "nogroup" and fail with:
#   insecure cache dir /tmp/.auto-apt-proxy-0. Must be owned by UID 0 and have permissions 700
# We cannot overwrite a configuration item using the APT_CONFIG environment
# variable, so instead we use it to set the Dir configuration option
# to /dev/null to force all apt settings to their defaults.
# There is currently no better way to disable this behavior. See also:
# https://bugs.debian.org/1031105
# https://salsa.debian.org/installer-team/debootstrap/-/merge_requests/90
AUTOPROXY=
eval "$(apt-config shell AUTOPROXY Acquire::http::Proxy-Auto-Detect)"
if [ -n "$AUTOPROXY" ] && [ -x "$AUTOPROXY" ] && [ -e /tmp/.auto-apt-proxy-0 ]; then
	TMP_APT_CONFIG=$(mktemp)
	echo "Dir \"/dev/null\";" > "$TMP_APT_CONFIG"
	chmod 644 "$TMP_APT_CONFIG"
fi

$prefix {{ CMD }} --variant=custom --mode={{ MODE }} \
	--setup-hook='env '"${AUTOPROXY:+APT_CONFIG='$TMP_APT_CONFIG'}"' container=lxc debootstrap --variant={{ VARIANT }} unstable "$1" {{ MIRROR }}' \
	- /tmp/debian-mm.tar {{ MIRROR }}
if [ -n "$AUTOPROXY" ] && [ -x "$AUTOPROXY" ] && [ -e /tmp/.auto-apt-proxy-0 ]; then
	rm "$TMP_APT_CONFIG"
fi

mkdir /tmp/debian-mm
tar --xattrs --xattrs-include='*' -C /tmp/debian-mm -xf /tmp/debian-mm.tar

mkdir /tmp/debian-debootstrap
tar --xattrs --xattrs-include='*' -C /tmp/debian-debootstrap -xf "cache/debian-unstable-{{ VARIANT }}.tar"

# diff cannot compare device nodes, so we use tar to do that for us and then
# delete the directory
tar -C /tmp/debian-debootstrap -cf dev1.tar ./dev
tar -C /tmp/debian-mm -cf dev2.tar ./dev
cmp dev1.tar dev2.tar >&2
rm dev1.tar dev2.tar
rm -r /tmp/debian-debootstrap/dev /tmp/debian-mm/dev

# remove downloaded deb packages
rm /tmp/debian-debootstrap/var/cache/apt/archives/*.deb
# remove aux-cache
rm /tmp/debian-debootstrap/var/cache/ldconfig/aux-cache
# remove logs
rm /tmp/debian-debootstrap/var/log/dpkg.log \
	/tmp/debian-debootstrap/var/log/bootstrap.log \
	/tmp/debian-debootstrap/var/log/alternatives.log \
	/tmp/debian-mm/var/log/bootstrap.log

# clear out /run except for /run/lock
find /tmp/debian-debootstrap/run/ -mindepth 1 -maxdepth 1 ! -name lock -print0 | xargs --no-run-if-empty -0 rm -r

# debootstrap doesn't clean apt
rm /tmp/debian-debootstrap/var/lib/apt/lists/127.0.0.1_debian_dists_unstable_main_binary-{{ HOSTARCH }}_Packages \
	/tmp/debian-debootstrap/var/lib/apt/lists/127.0.0.1_debian_dists_unstable_Release \
	/tmp/debian-debootstrap/var/lib/apt/lists/127.0.0.1_debian_dists_unstable_Release.gpg

if [ -e /tmp/debian-debootstrap/etc/machine-id ]; then
	rm /tmp/debian-debootstrap/etc/machine-id /tmp/debian-mm/etc/machine-id
fi
rm /tmp/debian-mm/var/cache/apt/archives/lock
rm /tmp/debian-mm/var/lib/apt/lists/lock
rm /tmp/debian-mm/var/lib/dpkg/arch

# workaround for https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=917773
# also needed for users that are created by systemd-sysusers before systemd 252
# https://github.com/systemd/systemd/pull/24534
for f in shadow shadow-; do
	if [ ! -e /tmp/debian-debootstrap/etc/$f ]; then
		continue
	fi
	if ! cmp /tmp/debian-debootstrap/etc/$f /tmp/debian-mm/etc/$f >&2; then
		echo patching /etc/$f >&2
		awk -v FS=: -v OFS=: -v SDE={{ SOURCE_DATE_EPOCH }} '{ print $1,$2,int(SDE/60/60/24),$4,$5,$6,$7,$8,$9 }' < /tmp/debian-mm/etc/$f > /tmp/debian-mm/etc/$f.bak
		cat /tmp/debian-mm/etc/$f.bak > /tmp/debian-mm/etc/$f
		rm /tmp/debian-mm/etc/$f.bak
	else
		echo no difference for /etc/$f >&2
	fi
done

# isc-dhcp-client postinst doesn't create this file in debootstrap run with
# unshared wrapper. The responsible postinst snippet was automatically added
# by dh_apparmor since isc-dhcp-client 4.4.3-P1-1.1
if [ -e /tmp/debian-debootstrap/etc/apparmor.d/local/sbin.dhclient ] && [ ! -s /tmp/debian-debootstrap/etc/apparmor.d/local/sbin.dhclient ]; then
	echo /sbin/setcap > /tmp/debian-debootstrap/etc/apparmor.d/local/sbin.dhclient
fi

# check if the file content differs
diff --unified --no-dereference --recursive /tmp/debian-debootstrap /tmp/debian-mm >&2

# check permissions, ownership, symlink targets, modification times using tar
# mtimes of directories created by mmdebstrap will differ, thus we equalize them first
for d in etc/apt/preferences.d/ etc/apt/sources.list.d/ etc/dpkg/dpkg.cfg.d/ var/log/apt/; do
	touch --date="@{{ SOURCE_DATE_EPOCH }}" /tmp/debian-debootstrap/$d /tmp/debian-mm/$d
done
# debootstrap never ran apt -- fixing permissions
for d in ./var/lib/apt/lists/partial ./var/cache/apt/archives/partial; do
	chroot /tmp/debian-debootstrap chmod 0700 $d
	chroot /tmp/debian-debootstrap chown _apt:root $d
done
tar -C /tmp/debian-debootstrap --numeric-owner --xattrs --xattrs-include='*' --sort=name --clamp-mtime --mtime="$(date --utc --date=@{{ SOURCE_DATE_EPOCH }} --iso-8601=seconds)" -cf /tmp/root1.tar .
tar -C /tmp/debian-mm --numeric-owner --xattrs --xattrs-include='*' --sort=name --clamp-mtime --mtime="$(date --utc --date=@{{ SOURCE_DATE_EPOCH }} --iso-8601=seconds)" -cf /tmp/root2.tar .
tar --full-time --verbose -tf /tmp/root1.tar > /tmp/root1.tar.list
tar --full-time --verbose -tf /tmp/root2.tar > /tmp/root2.tar.list
# despite SOURCE_DATE_EPOCH and --clamp-mtime, the timestamps in the tarball
# will slightly differ from each other in the sub-second precision (last
# decimals) so the tarballs will not be identical, so we use diff to compare
# content and tar to compare attributes
diff -u /tmp/root1.tar.list /tmp/root2.tar.list >&2
rm /tmp/root1.tar /tmp/root2.tar /tmp/root1.tar.list /tmp/root2.tar.list

rm /tmp/debian-mm.tar
rm -r /tmp/debian-debootstrap /tmp/debian-mm