setup_rootfs

#!/bin/sh -ex

dest_img="$1"

[ ! -d "$ROOTFS_BUILD_DIR" ] || rm -rf "$ROOTFS_BUILD_DIR"

mkdir "$ROOTFS_BUILD_DIR"

# being on a tmpfs inside the mount namespace is really nice.
# it can limit size of the file system, cleanup is free, and - of course - it's super fast.
# but mke2fs has problems with it, so no: mount -t tmpfs none "$ROOTFS_BUILD_DIR".
# however, not using a tmpfs leads other problems

mount -t tmpfs -o noatime none "$ROOTFS_BUILD_DIR"

tar -C "$ROOTFS_BUILD_DIR" -xf "$BASE_ROOTFS_TAR"

mkdir -p "$ROOTFS_BUILD_DIR/boot"

run_mounted() {
	# exporting in a loop is a hassle
	{
		grep -v '^#' .env.rootfs-customization
		echo ./customize_rootfs
		echo "$ROOTFS_BUILD_DIR"
	} | xargs -d '\n' env
}

# this includes /proc/sys/fs/binfmt_misc, which allows running the binaries inside
mount --rbind /proc/ "$ROOTFS_BUILD_DIR/proc"
# /dev/shm, /dev/random, /dev/urandom and the likes are required for GPG and such
mount --rbind /dev "$ROOTFS_BUILD_DIR/dev"
mount --bind . "$ROOTFS_BUILD_DIR/mnt"
mount --bind "$PACMAN_CACHE_DIR" "$ROOTFS_BUILD_DIR/var/cache/pacman/pkg"
mount --bind /etc/resolv.conf "$ROOTFS_BUILD_DIR/etc/resolv.conf"

run_mounted

umount "$ROOTFS_BUILD_DIR/etc/resolv.conf"
umount "$ROOTFS_BUILD_DIR/var/cache/pacman/pkg"
umount "$ROOTFS_BUILD_DIR/mnt"

umount -l "$ROOTFS_BUILD_DIR/dev"
umount -l "$ROOTFS_BUILD_DIR/proc"

apparent_size="$(du -xsm "$ROOTFS_BUILD_DIR" | awk '{ print $1 }')"
# this can fail because of the host FS
#mke2fs -L "system" -U "$ROOTFS_UUID" -d "$ROOTFS_BUILD_DIR" \
mke2fs -F -L "system" -U "$ROOTFS_UUID" -d "$ROOTFS_BUILD_DIR" \
	-O "^has_journal" \
	-m 2 \
	-t ext4 \
	"$dest_img" \
	$(( apparent_size * 105 / 100 + ROOTFS_WIGGLEROOM_MB ))M 2>&1

umount "$ROOTFS_BUILD_DIR"
rm -rf "$ROOTFS_BUILD_DIR"