#!/bin/sh
# Shebang line included so editors and shellcheck/shfmt know this contains
# shell code

# Helper functions for NUT server service handling

# In recent (relevant) versions of shellcheck busybox is a valid shell type
# shellcheck shell=busybox

# config_load is done by the sourcing script, before executing any functions in
# this file

# Pre-requisite sourcing for functions this script uses
# * /lib/functions.sh has been sourced
# * /lib/functions/nut/nut-common.sh has been sourced

# find_runas to find the RUNAS user should already have been
# run by nut-server initscript prior to calling
# ensure_usb_ups_access.

# Ensure the RUNAS user has access to the USB UPS device
ensure_usb_ups_access() {
	local ups="$1"
	local known_devname="$2"
	local cfg_vendorid
	local cfg_productid
	local device_owner
	local device_group
	local usb_bus
	local usb_dev
	local device_path
	local cur_devname
	local device_serial
	local sysfs_vendorid
	local sysfs_productid
	local serial
	# When no USB bus or USB device is found, the value returned in each case,
	# after printf,	will be '000', which is not a valid USB bus or USB device
	# number (i.e. it is a missing data indicator).
	local missing_usb_num="000"

	device_owner="$RUNAS"
	[ -n "$RUNAS" ] || {
		log_error "No RUNAS user specified. Skipping ups '$ups'" nut-server-service.sh nut-server-service
		return 1
	}

	device_group="$(id -gn "$RUNAS")" || {
		log_error "Unable to find group for RUNAS='$RUNAS'. Skipping ups '$ups'" nut-server-service.sh nut-server-service
		return 1
	}

	config_get cfg_vendorid "$ups" vendorid
	# replacement in variable parameter expansion is supported by ash in OpenWrt
	# since at least OpenWrt-24.10 (the previous stable release, which two
	# versions older than the targetted next release of OpenWrt (after
	# OpenWrt-25.12). This has been verified by the author of this script).
	if [ -n "$cfg_vendorid" ] && ! check_valid_hex_number "${cfg_vendorid/0x/}"; then
		log_error "Configured vendorid for '$ups' is not valid" nut-server-service.sh nut-server-service
		return 1
	fi

	# Configuration might not have a vendorid. This is allowed, but we have
	# nothing to do here in that case.
	[ -n "$cfg_vendorid" ] || return 0

	case "$cfg_vendorid" in
	0x*)
		cfg_vendorid="$(printf "%04x" "$cfg_vendorid")"
		;;
	*)
		cfg_vendorid="$(printf "%04x" "0x$cfg_vendorid")"
		;;
	esac

	config_get cfg_productid "$ups" productid
	if [ -n "$cfg_productid" ] && ! check_valid_hex_number "${cfg_productid/0x/}"; then
		log_error "Configured productid for '$ups' is not valid" nut-server-service.sh nut-server-service
		return 1
	fi

	# Configuration might not have a productid. This is allowed, but we have
	# nothing to do here in that case.
	[ -n "$cfg_productid" ] || return 0

	case "$cfg_productid" in
	0x*)
		cfg_productid="$(printf "%04x" "$cfg_productid")"
		;;
	*)
		cfg_productid="$(printf "%04x" "0x$cfg_productid")"
		;;
	esac

	config_get serial "$ups" serial

	# $'\x' syntax is supported by ash in OpenWrt since at least OpenWrt-24.10
	# (the previous stable release, which two versions older than the targetted
	# next release of OpenWrt (after OpenWrt-25.12). This has been verified by
	# the author of this script).
	# shellcheck disable=SC3003
	local NL=$'\n'

	# Loop on the idVendor of all USB devices attached to the system
	# We do not need any return values from this loop, which exists solely for the side-effects of
	# setting the appropriate device permissions and group, so subshell is okay.
	# IFS is set to newline *only*. Default IFS also includes tab and space
	# Disable globbing. `find` will still use patterns.
	set -f
	find /sys/devices -name idVendor -a -path '*/usb[0-9]*/*' | while IFS="$NL" read -r vendor_path; do
		set +f
		usb_bus=""
		usb_dev=""
		device_path=""
		cur_devname=""
		device_serial=""
		# Filter by vendor ID first

		sysfs_vendorid="$(cat "$vendor_path")"
		if [ -z "$sysfs_vendorid" ]; then
			log_error "Could not read vendor ID from $vendor_path" nut-server-service.sh nut-server-service
			continue
		fi

		if [ "$sysfs_vendorid" != "$cfg_vendorid" ]; then
			continue
		fi

		device_path="$(dirname "$vendor_path")"

		# Then filter by product ID

		sysfs_productid="$(cat "$device_path/idProduct")"

		if [ -z "$sysfs_productid" ]; then
			log_error "Could not read product ID from $device_path" nut-server-service.sh nut-server-service
			continue
		fi
		if [ "$sysfs_productid" != "$cfg_productid" ]; then
			continue
		fi

		# Next filter by serial (number), if provided

		# guard against disappearing device_path (e.g. due to 'bouncing' device connection)
		if [ ! -e "$device_path" ]; then
			continue
		fi

		# Only check against device serial number if a serial number is
		# in the configuration for this UPS
		if [ -n "$serial" ]; then
			device_serial="$(cat "$device_path/serial" 2>/dev/null)"

			if [ "$serial" != "$device_serial" ]; then
				continue
			fi
		fi

		usb_bus="$(printf "%03d" "$(cat "$device_path/busnum")")"
		usb_dev="$(printf "%03d" "$(cat "$device_path/devnum")")"

		# usb_bus and usb_dev must each be at least 001
		# a missing value will be present as 000 due to 'printf "%03d"'
		if [ "$usb_bus" = "$missing_usb_num" ] || [ "$usb_dev" = "$missing_usb_num" ]; then
			# If this sysfs device is not valid, keep looking (and ignore this
			# sysfs device).
			continue
		else
			# If we are called from hotplug, we know the device name, so skip any other devices
			cur_devname="/dev/bus/usb/$usb_bus/$usb_dev"
			if [ -n "$known_devname" ] && [ "$known_devname" != "$cur_devname" ]; then
				continue
			fi

			# guard against disappearing cur_devname (e.g. due to 'bouncing' device connection)
			if [ -e "$cur_devname" ]; then
				chmod 0660 "$cur_devname" || {
					log_error "'chmod' failed for $cur_devname (ups '$ups')" nut-server-service.sh nut-server-service
					continue
				}
				# Re-check in case device disappeared after chmod
				if [ -e "$cur_devname" ]; then
					chown "${device_owner}:${device_group}" "$cur_devname" || {
						log_error "'chown' failed for $cur_devname (ups '$ups')" nut-server-service.sh nut-server-service
						continue
					}
				fi
			else
				continue
			fi

			# Serial numbers are defined as unique, so do not loop further (on /sys/devices - while),
			# if serial was present and matched
			if [ -n "$serial" ]; then
				# Break out of while loop (so we do not process more 'find' results)
				break
			fi
			# If a serial number is not provided we need all vendor:product matches
			# to have permissions for NUT as we do not know the method used
			# to match UPS device to a configuration, in this script
			# (but if we have a known_devname, limit to that device)
		fi
		set -f
	done
	set +f
}