src: modularize repo layout into a library

This will greatly help us to structure the functionality and commands in
a more sane way. We will distribute the sources as actual libraries and
reuse code with imports instead of processing everything with m4 and
duplicating a lot of code.

1 files changed, 62 insertions, 0 deletions

diff --git a/src/lib/archroot.sh b/src/lib/archroot.sh
new file mode 100644
index 0000000..d7917da
--- /dev/null
+++ b/src/lib/archroot.sh
@@ -0,0 +1,62 @@
+#!/hint/bash
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+:
+
+# shellcheck disable=2034
+CHROOT_VERSION='v4'
+
+##
+#  usage : check_root $keepenv
+##
+orig_argv=("${BASH_SOURCE[0]}" "$@")
+check_root() {
+	local keepenv=$1
+
+	(( EUID == 0 )) && return
+	if type -P sudo >/dev/null; then
+		exec sudo --preserve-env=$keepenv -- "${orig_argv[@]}"
+	else
+		exec su root -c "$(printf ' %q' "${orig_argv[@]}")"
+	fi
+}
+
+##
+#  usage : is_btrfs( $path )
+# return : whether $path is on a btrfs
+##
+is_btrfs() {
+	[[ -e "$1" && "$(stat -f -c %T "$1")" == btrfs ]]
+}
+
+##
+#  usage : is_subvolume( $path )
+# return : whether $path is a the root of a btrfs subvolume (including
+#          the top-level subvolume).
+##
+is_subvolume() {
+	[[ -e "$1" && "$(stat -f -c %T "$1")" == btrfs && "$(stat -c %i "$1")" == 256 ]]
+}
+
+##
+#  usage : subvolume_delete_recursive( $path )
+#
+#    Find all btrfs subvolumes under and including $path and delete them.
+##
+subvolume_delete_recursive() {
+	local subvol
+
+	is_subvolume "$1" || return 0
+
+	while IFS= read -d $'\0' -r subvol; do
+		if ! subvolume_delete_recursive "$subvol"; then
+			return 1
+		fi
+	done < <(find "$1" -mindepth 1 -xdev -depth -inum 256 -print0)
+	if ! btrfs subvolume delete "$1" &>/dev/null; then
+		error "Unable to delete subvolume %s" "$subvol"
+		return 1
+	fi
+
+	return 0
+}