genenter

#!/bin/sh
set -eu

CWD="$(dirname "$0")"
ROOT="${ROOT:-$PWD/broot}"
REPOS="$PWD/repos.squashfs"
DISTDIR="${DISTDIR:-$PWD/distfiles}"
PKGDIR="${PKGDIR:-$PWD/packages}"

modprobe -q loop || true

mkdir -p "$REPOS.wrk"
mkdir -p "$DISTDIR" "$PKGDIR"

tmp="$(mktemp -d -t geniso.XXXXXXXXXX)"
wrk="$REPOS.wrk"
mount -o ro "$REPOS" "$tmp"
mount -o lowerdir="$tmp",upperdir="$ROOT",workdir="$wrk",xino=on -t overlay overlay "$tmp"
# xino=on required to keep python tests from failing due to inode number mismatch

mount -t tmpfs tmpfs "$tmp/mnt"
mkdir "$tmp/mnt/build" "$tmp/mnt/scripts" "$tmp/mnt/distfiles"
mount --bind "$PWD" "$tmp/mnt/build"
mount --bind -o ro "$CWD" "$tmp/mnt/scripts"
mount --bind -o ro "${BDISTDIR:-$(portageq envvar DISTDIR)}" "$tmp/mnt/distfiles"

mkdir -p "$tmp/usr/portage/distfiles"
mkdir -p "$tmp/usr/portage/packages"
mount --bind "$DISTDIR" "$tmp/usr/portage/distfiles"
mount --bind "$PKGDIR" "$tmp/usr/portage/packages"

mount -o nosuid,noexec,nodev -t sysfs sysfs "$tmp/sys"
mount -o nosuid,noexec,nodev -t proc proc "$tmp/proc"
mount -o nosuid,noexec -t devtmpfs devtmpfs "$tmp/dev"
mount -o nosuid,noexec -t devpts devpts "$tmp/dev/pts"

# Use pivot_root to avoid some problems with sandbox in chroot
# https://bugs.gentoo.org/922960
trap true INT QUIT TERM
set +e
#env -i TERM=linux HOME=/root chroot "$tmp" /bin/bash -l "$@"
env -i TERM=linux HOME=/root unshare -m /bin/sh -c '
umask 022
cd "$1"; shift
mount --bind . mnt
pivot_root mnt mnt
exec chroot . /bin/bash -l "$@"
' - "$tmp" "$@"
rc=$?
set -e

umount "$tmp/dev/pts" "$tmp/dev" "$tmp/proc" "$tmp/sys"
umount "$tmp/usr/portage/packages" "$tmp/usr/portage/distfiles"
umount "$tmp/mnt/build" "$tmp/mnt/scripts" "$tmp/mnt/distfiles" "$tmp/mnt"
umount "$tmp"
umount "$tmp"
rm -r "$tmp" "$wrk"
exit $rc