Initial version

This is based on and inspired by https://github.com/WhatAmISupposedToPutHere/fex-rootfs/tree/c8f7c6ce1afa3e1bb611d7dc11c03769aace39e4/systemd

Author: davide125

LICENSE

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+Copyright (c) 2024 Davide Cavalca
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# fex-emu-rootfs-generator
+
+WIP systemd generator for the fex rootfs

fex-emu-rootfs-generator.sh

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+#!/bin/sh
+
+set -eu
+
+layers=""
+for f in /usr/share/fex-emu/layers/*; do
+  [ -z "$layers" ] && layers=$f || layers="$layers $f"
+done
+dest="$1"
+
+units=""
+mounts=""
+for layer in $layers; do
+  name="$(basename $layer .erofs)"
+  mount=/run/fex-emu/layers/$name
+  unit="$(systemd-escape $mount --path --suffix mount)"
+  cat > $dest/$unit <<EOF
+[Unit]
+Description=FEX RootFS layer for $name
+
+[Mount]
+What=$layer
+Where=$mount
+EOF
+  [ -z "$units" ] && units=$unit || units="$units $unit"
+  [ -z "$mounts" ] && mounts=$mount || mounts="$mounts $mount"
+done
+
+rootfs=$(systemd-escape /run/fex-emu/rootfs --path --suffix mount)
+cat > $dest/$rootfs <<EOF
+[Unit]
+Description=FEX RootFS
+BindsTo=$units
+After=$units
+
+[Mount]
+What=overlay
+Where=/run/fex-emu/rootfs
+Type=overlay
+Options=lowerdir=$(echo $mounts|tr ' ' :),upperdir=/run/fex-emu/writable,workdir=/run/fex-emu/workdir
+
+[Install]
+WantedBy=multi-user.target
+EOF
+
+mkdir -p $dest/multi-user.target.wants/
+ln -sf "../$rootfs" $dest/multi-user.target.wants/$rootfs