1 files changed, 42 insertions, 0 deletions
diff --git a/9pmounthook/customize.sh b/9pmounthook/customize.sh
new file mode 100755
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--- /dev/null
+++ b/9pmounthook/customize.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+# Copyright 2022 Helmut Grohne <helmut@subdivi.de>
+# SPDX-License-Identifier: MIT
+#
+# This is a mmdebstrap customize hook that adds a systemd-generator that causes
+# 9p filesystems to be automatically mounted to /media/$SOMETAG during boot.
+# You can enable it by passing the containing directory to --hook-dir.
+# In order to add a 9p filesystem to your VM, pass
+# -virtfs local,security_model=none,mount_tag=$SOMETAG,path=$SOMEDIR
+# Note that the linux-image-cloud-* does not include a 9p driver.
+
+set -eu
+GENERATOR_PATH="$1/etc/systemd/system-generators/9p-generator"
+mkdir -p "${GENERATOR_PATH%/*}"
+cat >"$GENERATOR_PATH" << 'ENDOFGENERATOR'
+#!/bin/sh
+
+UNITDIR=$1
+
+modprobe 9pnet_virtio || exit 0
+
+for tagfile in /sys/bus/virtio/devices/*/mount_tag; do
+	tag=$(cat "$tagfile") || continue
+	test -z "$tag" && continue
+	mountpoint="/media/$tag"
+	mkdir -p "$mountpoint"
+	unitname="$(systemd-escape -p "$mountpoint").mount"
+	cat > "$UNITDIR/$unitname" <<ENDOFUNIT
+[Unit]
+Description=9p mount for tag $tag
+
+[Mount]
+What=$tag
+Where=$mountpoint
+Type=9p
+Options=trans=virtio
+ENDOFUNIT
+	mkdir -p "$UNITDIR/remote-fs.target.wants"
+	ln -s "../$unitname" "$UNITDIR/remote-fs.target.wants/$unitname"
+done
+ENDOFGENERATOR
+chmod 755 "$GENERATOR_PATH"