Merge pull request #22 from macmpi/dev

version 1.2

README.md

@@ -25,15 +25,18 @@ Extra files may be added next to `headless.apkovl.tar.gz` to customise boostrapp
 - `interfaces`[^3] (*optional*): define network interfaces at will, if defaults DCHP-based are not suitable.
 - `authorized_keys` (*optional*): provide client's public SSH key to secure `root` ssh login.
 - `ssh_host_*_key*` (*optional*): provide server's custom ssh keys to be injected (may be stored), instead of using bundled ones[^2] (not stored). Providing an empty key file will trigger new keys generation (ssh server may take longer to start).
-
-
-**Goody:** seamless USB-serial & USB-ethernet gadget mode (PiZero for instance):\
-On supporting Pi devices, just add `dtoverlay=dwc2,dr_mode=peripheral` in `usercfg.txt` (or `config.txt`), and plug USB cable into host Computer port.\
-Serial terminal can then be connected-to from host Computer (e.g. `cu -l ttyACM0` on Linux. xon/xoff flow control).\
-Alternatively, with host Computer set-up to share networking with USB interface as 10.42.0.1 gateway, one can log into device from host with: `ssh root@10.42.0.2`.
+- `auto-updt` (*optional*): allow apkovl file automatic update with latest from master branch. If it contains *reboot* keyword all in one line, system will reboot after succesful update (unless ssh session is active or `unattended.sh` script is available).
 
 Main execution steps are logged: `cat /var/log/messages | grep headless`.
 
+## Goody:
+Seamless USB-serial & USB-ethernet gadget mode (*e.g. PiZero*):
+- Make sure dwc2/dwc3 driver is loaded accordingly, and device configuration is set to `peripheral` mode: this may be hardware (including cable) and/or software driven.\
+(on supporting Pi devices, just add `dtoverlay=dwc2,dr_mode=peripheral` in `usercfg.txt` (or `config.txt`) to force by software)
+- Plug USB cable into host Computer port before boot.\
+Serial terminal can then be connected-to from host Computer (e.g. `cu -l ttyACM0` on Linux. xon/xoff flow control).\
+Alternatively, with host Computer set-up to share networking with USB interface as 10.42.0.1 gateway, one can log into device from host with: `ssh root@10.42.0.2`.
+
 [^1]: Initial boot fully preserves system's original state (config files & installed packages): a fresh system will therefore come-up as unconfigured.
 
 [^2]: About bundled ssh keys: this overlay is meant to **quickly bootstrap** system in order to then proceed with proper install; therefore it purposely embeds [some ssh keys](https://github.com/macmpi/alpine-linux-headless-bootstrap/tree/main/overlay/tmp/.trash) so that bootstrapping is as fast as possible. Those temporary keys are moved in RAM /tmp: they will **not be stored/reused** once actual system install is performed (whether or not ssh server is installed in final setup).

headless.apkovl.tar.gz.sha512

@@ -0,0 +1 @@
+36892e9aa76807941602160ff62948c8953eefa36f9b386a0c7302fc46710b473a3e14b7eaf223a1ae6ac6454a839c78049c311fdbd50a204b2a011cb8faa474  headless.apkovl.tar.gz

make.sh

@@ -30,7 +30,8 @@ if [ -n "$build_path" ]; then
 	doas tar cv -C "$build_path"/overlay --no-recursion \
 		$(doas find "$build_path"/overlay/ | sed "s|$build_path/overlay/||" | sort | xargs ) | \
 			gzip -c9n > headless.apkovl.tar.gz
-	TZ=UTC touch -cm -t "$t_stamp" headless.apkovl.tar.gz
+	sha512sum headless.apkovl.tar.gz > headless.apkovl.tar.gz.sha512
+	TZ=UTC touch -cm -t "$t_stamp" headless.apkovl.tar.gz*
 	doas rm -rf "$build_path"
 fi
 

overlay/usr/local/bin/headless_bootstrap

@@ -3,7 +3,7 @@
 # SPDX-FileCopyrightText: Copyright 2022-2023, macmpi
 # SPDX-License-Identifier: MIT
 
-HDLSBSTRP_VERSION="1.1"
+HDLSBSTRP_VERSION="1.2"
 
 _apk() {
 	local cmd="$1"
@@ -12,11 +12,11 @@ _apk() {
 	case $cmd in
 		add) # install only if not already present
 			if ! apk info | grep -wq "${pkg}"; then
-				apk add "$pkg" && printf '%s ' "${pkg}" >> /tmp/.trash/installed
+				apk add "$pkg" && printf '%s ' "${pkg}" >>/tmp/.trash/installed
 			fi
 		;;
 		del) # delete only if previously installed
-			if grep -wq "$pkg" /tmp/.trash/installed > /dev/null 2>&1; then
+			if grep -wq "$pkg" /tmp/.trash/installed >/dev/null 2>&1; then
 				apk del "$pkg" && sed -i 's/\b'"${pkg}"'\b//' /tmp/.trash/installed
 			fi
 		;;
@@ -27,14 +27,14 @@ _apk() {
 }
 
 _preserve() {
-# create a back-up of element (file, folder, symlink)
+# Create a back-up of element (file, folder, symlink).
 	[ -z "${1}" ] && return 1
 	[ -e "${1}" ] && cp -a "${1}" "${1}".orig
 }
 
 _restore() {
-# remove element (file, folder, symlink) and replace by
-# previous back-up if available
+# Remove element (file, folder, symlink) and replace by
+# previous back-up if available.
 	[ -z "${1}" ] && return 1
 	rm -rf "${1}"
 	[ -e "${1}".orig ] && mv -f "${1}".orig "${1}"
@@ -46,11 +46,11 @@ alias _logger='logger -st "${0##*/}"'
 ##### End of part to be duplicated into headless_cleanup (do not alter!)
 
 _prep_cleanup() {
-## Prep for final headless_cleanup
-# clears any installed packages and settings
-# copy begininng of this file to keep functions
-sed -n '/^#* End .*alter!)$/q;p' /usr/local/bin/headless_bootstrap > /tmp/.trash/headless_cleanup
-cat <<-EOF >> /tmp/.trash/headless_cleanup
+## Prep for final headless_cleanup:
+# clears any installed packages and settings.
+# Copy begininng of this file to keep functions.
+sed -n '/^#* End .*alter!)$/q;p' /usr/local/bin/headless_bootstrap >/tmp/.trash/headless_cleanup
+cat <<-EOF >>/tmp/.trash/headless_cleanup
 	# Redirect stdout and errors to console as service won't show messages
 	exec 1>/dev/console 2>&1
 
@@ -64,44 +64,45 @@ cat <<-EOF >> /tmp/.trash/headless_cleanup
 	_restore "/etc/hostname"
 	rm -f /etc/modprobe.d/headless_gadget.conf
 
-	# remove from boot service to avoid spurious openrc recalls from unattended script
+	# Remove from boot service to avoid spurious openrc recalls from unattended script.
 	rm -f /etc/runlevels/default/headless_bootstrap
 	rm -f /usr/local/bin/headless_bootstrap
 
-	# Run unattended script if available
-	install -m755 "${ovlpath}"/unattended.sh /tmp/headless_unattended > /dev/null 2>&1 && \
+	# Run unattended script if available.
+	install -m755 ${ovlpath}/unattended.sh /tmp/headless_unattended >/dev/null 2>&1 && \
 		_logger "Starting headless_unattended service" && \
 		rc-service headless_unattended start
 
 	rm -f /etc/init.d/headless_*
 	_logger "Clean-up done, enjoy !"
-	cat /tmp/.trash/banner > /dev/console
-	if [ -c /dev/ttyGS0 ]; then
-		# Enabling terminal login into ttyGS0 serial for 60 sec
-		# no choice than making permanent change to pre 3.19 versions of /etc/securetty
-		grep -q "ttyGS0" /etc/securetty || echo "ttyGS0" >> /etc/securetty
-		/sbin/getty -L 115200 ttyGS0 vt100 &
+	cat /tmp/.trash/banner >/dev/console
+	if [ -c /dev/ttyGS${gdgt_id} ]; then
+		# Enabling terminal login into valid serial port:
+		# no choice than making permanent change to /etc/securetty (Alpine 3.19 already has ttyGS0).
+		grep -q "ttyGS${gdgt_id}" /etc/securetty || echo "ttyGS${gdgt_id}" >>/etc/securetty
+		/sbin/getty -L 115200 /dev/ttyGS${gdgt_id} vt100 &
 	fi
+	exit 0
 	EOF
 chmod +x /tmp/.trash/headless_cleanup
 }
 
 _setup_sshd() {
-## Setup temporary SSH server (root login, no password)
-# We use some bundled (or optionaly provided) keys to avoid generation at startup and save time
+## Setup temporary SSH server (root login, no password):
+# we use some bundled (or optionaly provided) keys to avoid generation at startup and save time.
 _apk add openssh-server
 _preserve "/etc/ssh/sshd_config"
 _preserve "/etc/conf.d/sshd"
 
-cat <<-EOF > /etc/ssh/sshd_config
+cat <<-EOF >/etc/ssh/sshd_config
 	PermitRootLogin yes
 	Banner /tmp/.trash/banner
 	EOF
 
-# Client authorized_keys or no authentication
-if install -m600 "${ovlpath}"/authorized_keys /tmp/.trash/authorized_keys > /dev/null 2>&1; then
+# Client authorized_keys or no authentication.
+if install -m600 "${ovlpath}"/authorized_keys /tmp/.trash/authorized_keys >/dev/null 2>&1; then
 	_logger "Enabling public key SSH authentication..."
-	cat <<-EOF >> /etc/ssh/sshd_config
+	cat <<-EOF >>/etc/ssh/sshd_config
 		AuthenticationMethods publickey
 		AuthorizedKeysFile /tmp/.trash/authorized_keys
 		# relax strict mode as authorized_keys are inside /tmp
@@ -109,7 +110,7 @@ if install -m600 "${ovlpath}"/authorized_keys /tmp/.trash/authorized_keys > /dev
 		EOF
 else
 	_logger "No SSH authentication."
-	cat <<-EOF >> /etc/ssh/sshd_config
+	cat <<-EOF >>/etc/ssh/sshd_config
 		AuthenticationMethods none
 		PermitEmptyPasswords yes
 		EOF
@@ -118,8 +119,8 @@ fi
 # Server keys: inject optional custom keys, or generate new (might be stored),
 # or use bundeled ones (not stored)
 local keygen_stance="sshd_disable_keygen=yes"
-if install -m600 "${ovlpath}"/ssh_host_*_key* /etc/ssh/ > /dev/null 2>&1; then
-	# check for empty key within injected ones: if found, generate new keys
+if install -m600 "${ovlpath}"/ssh_host_*_key* /etc/ssh/ >/dev/null 2>&1; then
+	# Check for empty key within injected ones: if found, generate new keys.
 	if find /etc/ssh/ -maxdepth 1 -type f -name 'ssh_host_*_key*' -empty | grep -q .; then
 		rm /etc/ssh/ssh_host_*_key*
 		keygen_stance=""
@@ -130,63 +131,103 @@ if install -m600 "${ovlpath}"/ssh_host_*_key* /etc/ssh/ > /dev/null 2>&1; then
 	fi
 else
 	_logger "Using bundled ssh keys from RAM..."
-	cat <<-EOF >> /etc/ssh/sshd_config
+	cat <<-EOF >>/etc/ssh/sshd_config
 		HostKey /tmp/.trash/ssh_host_ed25519_key
 		HostKey /tmp/.trash/ssh_host_rsa_key
 		EOF
 fi
 
-echo "$keygen_stance" >> /etc/conf.d/sshd
+echo "$keygen_stance" >>/etc/conf.d/sshd
 rc-service sshd restart
 }
 
+_updt_apkovl() {
+## Update apkovl overlay file & eventually reboot
+# URL redirects to apkovl file on github master: is.gd shortener provides basic analytics.
+# Analytics are public and can be checked at https://is.gd/stats.php?url=apkovl_master
+# Privacy policy: https://is.gd/privacy.php
+local file_url="https://is.gd/apkovl_master"
+local sha_url="https://github.com/macmpi/alpine-linux-headless-bootstrap/raw/main/headless.apkovl.tar.gz.sha512"
+local updt_status="failed, keeping original version"
+
+if wget -q -O /tmp/apkovl -T 10 "$file_url" >/dev/null 2>&1 && \
+	wget -q -O /tmp/sha -T 10 "$sha_url" >/dev/null 2>&1 && \
+	[ "$( sha512sum /tmp/apkovl | awk '{print $1}' )" = "$( awk '{print $1}' /tmp/sha )" ]; then
+		_is_ro && mount -o remount,rw "${ovlpath}"
+		cp /tmp/apkovl "${ovl}"
+		_is_ro && mount -o remount,ro "${ovlpath}"
+		! [ "$( sha512sum "${ovl}" | awk '{print $1}' )" = "$( awk '{print $1}' /tmp/sha )" ] && \
+			_logger "Bad update: original apkovl file may be altered, please check!..." && return 1
+		updt_status="successful"
+fi
+rm -f /tmp/apkovl /tmp/sha
+_logger "Update $updt_status"
+if [ "$updt_status" = "successful" ]; then
+	printf '%s\n\n' "Updated" >>/tmp/.trash/banner
+else
+	printf '\n' >>/tmp/.trash/banner
+	return 1
+fi
+# Reboot if specified in auto-updt file (and no ssh session ongoing nor unattended.sh script available).
+! pgrep -a -P "$( cat /run/sshd.pid 2>/dev/null )" 2>/dev/null | grep -q "sshd: root@pts" && \
+	! [ -f "${ovlpath}"/unattended.sh ] && \
+		grep -q "^reboot$" "${ovlpath}"/auto-updt && \
+			_logger "Will reboot in 3sec..." && sleep 3 && reboot
+exit 0
+}
+
 _tst_version() {
-# Tested URL redirects to github project page: is.gd shortener provides basic analytics.
+## Compare current version with latest online, notify & eventally calls for update
+# URL redirects to github project page: is.gd shortener provides basic analytics.
 # Analytics are public and can be checked at https://is.gd/stats.php?url=apkovl_run
 # Privacy policy: https://is.gd/privacy.php
-local new_vers=""
-local status="failed"
+local vers=""
 local ref="/macmpi/alpine-linux-headless-bootstrap/releases/tag/v"
-if wget -q -O /tmp/homepg -T 10 https://is.gd/apkovl_run > /dev/null 2>&1; then
-	status="success"
-	ver="$( grep -o "$ref.*\"" /tmp/homepg | grep -Eo '[0-9]+[\.[0-9]+]*' )"
+local url="https://is.gd/apkovl_run"
+
+if wget -q -O /tmp/homepg -T 10 "$url" >/dev/null 2>&1; then
+	_logger "Internet access: success"
+	vers="$( grep -o "$ref.*\"" /tmp/homepg | grep -Eo '[0-9]+[\.[0-9]+]*' )"
 	rm -f /tmp/homepg
-	[ -n "$ver" ] && ! [ "$ver" = "$HDLSBSTRP_VERSION" ] && \
-		new_vers="!! Version $ver is available on Github project page !!" && \
-		_logger "$new_vers" && \
-		printf '%s\n\n' "$new_vers" >> /tmp/.trash/banner
+	if [ -n "$vers" ] && ! [ "$vers" = "$HDLSBSTRP_VERSION" ]; then
+		vers="!! Version $vers is available on Github project page !!"
+		_logger "$vers"
+		printf '%s\n' "$vers" >>/tmp/.trash/banner
+		# Optionally update apkovl if key-file allows it.
+		if [ -f "${ovlpath}"/auto-updt ]; then
+			_logger "Updating overlay file..."
+			_updt_apkovl &
+		else
+			_logger "(check doc to enable auto-update)"
+			printf '%s\n\n' "(check doc to enable auto-update)" >>/tmp/.trash/banner
+		fi
+	fi
+else
+	_logger "Internet access: failed"
 fi
-_logger "Internet access: $status"
 }
 
 _setup_networking() {
-## Setup Network interfaces
-local has_wifi
+## Setup network interfaces.
+local has_wifi wlan_lst
 _has_wifi() { return "$has_wifi"; }
 
-find /sys/class/ieee80211/*/device/net/* -maxdepth 0 -type d -exec basename {} \; > /tmp/.wlan_list 2>/dev/null
-[ -s /tmp/.wlan_list ] && [ -f "${ovlpath}"/wpa_supplicant.conf ]
+wlan_lst="$( find /sys/class/net/*/phy80211 -exec \
+	sh -c 'printf %s\| "$( basename "$( dirname "$0" )" )"' {} \; 2>/dev/null )"
+wlan_lst="${wlan_lst%\|}"
+[ -n "$wlan_lst" ] && [ -f "${ovlpath}"/wpa_supplicant.conf ]
 has_wifi=$?
-if _has_wifi; then
-	_logger "Configuring wifi..."
-	_apk add wpa_supplicant
-	_preserve "/etc/wpa_supplicant/wpa_supplicant.conf"
-	install -m600 "${ovlpath}"/wpa_supplicant.conf /etc/wpa_supplicant/wpa_supplicant.conf
-	rc-service wpa_supplicant restart
-else
-	_logger "No wifi interface or SSID/pass file supplied"
-fi
 
 _preserve "/etc/network/interfaces"
-if ! install -m644 "${ovlpath}"/interfaces /etc/network/interfaces > /dev/null 2>&1; then
+if ! install -m644 "${ovlpath}"/interfaces /etc/network/interfaces >/dev/null 2>&1; then
 	_logger "No interfaces file supplied, building defaults..."
-	cat <<-EOF > /etc/network/interfaces
+	cat <<-EOF >/etc/network/interfaces
 		auto lo
 		iface lo inet loopback
 
 		EOF
 	for dev in /sys/class/net/*; do
-		# shellcheck disable=SC2034  # Unused IFINDEX while still sourced from uevent
+		# shellcheck disable=SC2034  # Unused IFINDEX while still sourced from uevent.
 		local DEVTYPE INTERFACE IFINDEX
 		DEVTYPE=""
 		# shellcheck source=/dev/null
@@ -195,31 +236,37 @@ if ! install -m644 "${ovlpath}"/interfaces /etc/network/interfaces > /dev/null 2
 			lo)
 				;;
 			eth)
-				cat <<-EOF >> /etc/network/interfaces
+				cat <<-EOF >>/etc/network/interfaces
 					auto $INTERFACE
 					iface $INTERFACE inet dhcp
 
 					EOF
 				;;
 			*)
-				_has_wifi && grep -q "$INTERFACE" /tmp/.wlan_list && \
-					cat <<-EOF >> /etc/network/interfaces
+				# According to below we could rely on DEVTYPE for wlan devices
+				# https://lists.freedesktop.org/archives/systemd-devel/2014-January/015999.html
+				# but...some wlan might still be ill-behaved: use wlan_lst
+				# shellcheck disable=SC2169  # ash does support string replacement.
+				_has_wifi && ! [ "${wlan_lst/$INTERFACE/}" = "$wlan_lst" ] && \
+					cat <<-EOF >>/etc/network/interfaces
 						auto $INTERFACE
 						iface $INTERFACE inet dhcp
 
 						EOF
+				# Ensure considered gadget interface is actually the connected one (may have several).
 				[ "$DEVTYPE" = "gadget" ] && \
-					cat <<-EOF >> /etc/network/interfaces && cat <<-EOF > /etc/resolv.conf
-						auto $INTERFACE
-						iface $INTERFACE inet static
-						    address 10.42.0.2/24
-						    gateway 10.42.0.1
+					find /sys/class/udc/*/device/gadget."${gdgt_id}"/net/"$INTERFACE" -maxdepth 0 >/dev/null 2>&1 && \
+							cat <<-EOF >>/etc/network/interfaces && cat <<-EOF >/etc/resolv.conf
+								auto $INTERFACE
+								iface $INTERFACE inet static
+								    address 10.42.0.2/24
+								    gateway 10.42.0.1
 
-						EOF
-						nameserver 208.67.222.222
-						nameserver 208.67.220.220
+								EOF
+								nameserver 208.67.222.222
+								nameserver 208.67.220.220
 
-						EOF
+								EOF
 				;;
 		esac
 	done
@@ -230,35 +277,53 @@ echo "Using following network interfaces:"
 cat /etc/network/interfaces
 echo "###################################"
 
+if _has_wifi && grep -qE "$wlan_lst" /etc/network/interfaces; then
+	_logger "Configuring wifi..."
+	_apk add wpa_supplicant
+	_preserve "/etc/wpa_supplicant/wpa_supplicant.conf"
+	install -m600 "${ovlpath}"/wpa_supplicant.conf /etc/wpa_supplicant/wpa_supplicant.conf
+	rc-service wpa_supplicant restart
+else
+	_logger "No wifi interface or SSID/pass file supplied"
+fi
+
 _preserve "/etc/hostname"
-echo "alpine-headless" > /etc/hostname
+echo "alpine-headless" >/etc/hostname
 hostname -F /etc/hostname
 
 rc-service networking restart
-rm -f /tmp/.wlan_list
 }
 
 _setup_gadget() {
-## load composite USB Serial/USB Ethernel driver & setup terminal
+## Load composite USB Serial/USB Ethernel driver & setup terminal.
 _logger "Enabling USB-gadget Serial and Ethernet ports"
-lsmod | grep -q "dwc2" || modprobe -qs dwc2
-# remove conflicting modules in case they were initially loaded (cmdline.txt)
-modprobe -rq g_serial g_ether g_cdc
-modprobe -q g_cdc && sleep 1
-# once driver has settled check if cable is connected: unload if not
-[ "$( cat "$udc_gadget"/current_speed )" = "UNKNOWN" ] && \
-	_logger "USB cable not connected !!" && modprobe -rq g_cdc && return 1
+# Remove conflicting modules in case they were initially loaded (cmdline.txt).
+modprobe -r g_serial g_ether g_cdc
+modprobe g_cdc
+# Wait for g_cdc to settle and serial ports become available
+timeout 1 sh <<-EOF
+	while ! grep -q "ttyGS" /proc/devices; do sleep 0.2; done
+	EOF
 
-# default serial config: xon/xoff flow control
-stty -g -F /dev/ttyGS0 >/dev/null 2>&1
-# notes to users willing to connect from Linux Ubuntu-based host terminal:
-# - user on host needs to be part of dialout group (reboot required), and
-# - disable spurious AT commands from ModemManager on host-side Gadget serial port
-# you may create a /etc/udev/rules.d/99-ttyacms-gadget.rules as per:
-# https://linux-tips.com/t/prevent-modem-manager-to-capture-usb-serial-devices/284/2
-# ATTRS{idVendor}=="0525" ATTRS{idProduct}=="a4aa", ENV{ID_MM_DEVICE_IGNORE}="1"
-
-setconsole /dev/ttyGS0
+# Determine which gadget ID is connected with USB cable (assume just one max).
+# (setting console to unconnected serial port would block boot)
+gdgt_id="$( find /sys/class/udc/*/current_speed -exec \
+	sh -c 'grep -vq "UNKNOWN" "$0" && find ${0/current_speed/}device/gadget.* -maxdepth 0' {} \; \
+		| sed 's/\/.*gadget\.//' )"
+if [ -c /dev/ttyGS"${gdgt_id}" ]; then
+	# Default serial config: xon/xoff flow control.
+	stty -F /dev/ttyGS"${gdgt_id}"
+	setconsole /dev/ttyGS"${gdgt_id}"
+	# Notes to users willing to connect from Linux Ubuntu-based host terminal:
+	# - user on host needs to be part of dialout group (reboot required), and
+	# - disable spurious AT commands from ModemManager on host-side Gadget serial port
+	# one may create a /etc/udev/rules.d/99-ttyacms-gadget.rules as per:
+	# https://linux-tips.com/t/prevent-modem-manager-to-capture-usb-serial-devices/284/2
+	# ATTRS{idVendor}=="0525" ATTRS{idProduct}=="a4aa", ENV{ID_MM_DEVICE_IGNORE}="1"
+else
+	_logger "USB-gadget port not connected !"
+	modprobe -r g_cdc
+fi
 }
 
 
@@ -269,31 +334,35 @@ setconsole /dev/ttyGS0
 exec 1>/dev/console 2>&1
 _logger "Alpine Linux headless bootstrap v$HDLSBSTRP_VERSION by macmpi"
 
-# help randomness for wpa_supplicant and sshd (urandom until 3.16)
+# Help randomness for wpa_supplicant and sshd (urandom until 3.16).
 rc-service seedrng restart || rc-service urandom restart
 
-# setup USB gadget mode if such device mode is enabled
-udc_gadget="$( dirname "$( find -L /sys/class/udc/* -maxdepth 2 -type f -name "is_a_peripheral" 2>/dev/null)" )"
-[ "$( cat "$udc_gadget"/is_a_peripheral 2>/dev/null )" = "0" ] && \
-	_setup_gadget
+# Setup USB gadget ports if some ports are enabled in peripheral mode.
+# Note: we assume dwc2/dwc3 is pre-loaded, we just check mode.
+gdgt_id=""
+find /sys/class/udc/*/is_a_peripheral -print0 2>/dev/null | \
+	xargs -0 cat 2>/dev/null | grep -q "0" && \
+		_setup_gadget
 
-# Determine ovl file location
-# grab used ovl filename from dmesg
+# Determine ovl file location.
+# Grab used ovl filename from dmesg.
 ovl="$( dmesg | grep -o 'Loading user settings from .*:' | awk '{print $5}' | sed 's/:.*$//' )"
 if [ -f "${ovl}" ]; then
 	ovlpath="$( dirname "$ovl" )"
 else
-	# search path again as mountpoint have been changed later in the boot process...
+	# Search path again as mountpoint have been changed later in the boot process...
 	ovl="$( basename "${ovl}" )"
 	ovlpath=$( find /media -maxdepth 2 -type d -path '*/.*' -prune -o -type f -name "${ovl}" -exec dirname {} \; | head -1 )
 	ovl="${ovlpath}/${ovl}"
 fi
 
-# Create banner file
+# Create banner file.
 warn=""
-grep -q "${ovlpath}.*[[:space:]]ro[[:space:],]" /proc/mounts; RO=$?
-[ "$RO" -eq "0" ] && warn="(remount partition rw!)"
-cat <<-EOF > /tmp/.trash/banner
+grep -q "${ovlpath}.*[[:space:]]ro[[:space:],]" /proc/mounts; is_ro=$?
+_is_ro() { return "$is_ro"; }
+
+_is_ro && warn="(remount partition rw!)"
+cat <<-EOF >/tmp/.trash/banner
 
 	Alpine Linux headless bootstrap v$HDLSBSTRP_VERSION by macmpi
 	
@@ -306,12 +375,12 @@ cat <<-EOF > /tmp/.trash/banner
 
 _setup_networking
 
-# Test latest available version online
-# Can be skipped by creating a 'opt-out'-named dummy file aside apkovl file
+# Test latest available version online.
+# Can be skipped by creating a 'opt-out'-named dummy file aside apkovl file.
 [ -f "${ovlpath}"/opt-out ] || _tst_version &
 
-# setup sshd unless unattended.sh script prevents it
-grep -q "^#NO_SSH$" "${ovlpath}"/unattended.sh > /dev/null 2>&1 \
+# Setup sshd unless unattended.sh script prevents it.
+grep -q "^#NO_SSH$" "${ovlpath}"/unattended.sh >/dev/null 2>&1 \
 	|| _setup_sshd
 
 _prep_cleanup

sample_auto-updt

@@ -0,0 +1,10 @@
+# SPDX-FileCopyrightText: Copyright 2022-2023, macmpi
+# SPDX-License-Identifier: MIT
+
+# Automated reboot after update is cancelled if:
+# - there is an opened ssh session
+# - unattended.sh script is provided
+
+# Uncomment line below to enable reboot after update
+#reboot
+

sample_unattended.sh

@@ -37,10 +37,11 @@ else
 fi
 
 # also works in case volume is mounted read-only
-grep -q "${ovlpath}.*[[:space:]]ro[[:space:],]" /proc/mounts; RO=$?
-[ "$RO" -eq "0" ] && mount -o remount,rw "${ovlpath}"
+grep -q "${ovlpath}.*[[:space:]]ro[[:space:],]" /proc/mounts; is_ro=$?
+_is_ro() { return "$is_ro"; }
+_is_ro && mount -o remount,rw "${ovlpath}"
 rm -f "${ovl}"
-[ "$RO" -eq "0" ] && mount -o remount,ro "${ovlpath}"
+_is_ro && mount -o remount,ro "${ovlpath}"
 
 ########################################################