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1.1
date	2024.03.30.06.42.10;	author thorpej;	state Exp;
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commitid	Jsh7tW4WkRLwn94F;


desc
@@


1.1
log
@Add an example devpubd hook that detects the generic USB interface
portion of a Tigard debug board and changes the permissions of the
appropriate /dev/ugenN.* nodes to allow access without superuser
permissions, suitable for using e.g. openocd with the device.

This example can be easily modified to support other generic USB devices
that have user-space drivers where running as the superuser is not desired.
@
text
@#!/bin/sh -
#
# $NetBSD$
#
# Look for a Tigard (https://github.com/tigard-tools/tigard) debug
# board and change the permissions to 0660.
#
# Written by Jason R. Thorpe, March 2024.  Public domain.
#

export LC_ALL=C

event="$1"
shift
devices=$@@

orig_perms=0600
new_perms=0660

orig_group=wheel
new_group=wheel

device_name=tigard

is_target_device()
{
	local vendor_string
	local product_string

	vendor_string="$(drvctl -p $1 vendor-string)"
	product_string="$(drvctl -p $1 product-string)"

	if [ x"$vendor_string" = x"SecuringHardware.com" -a \
	     x"$product_string" = x"Tigard V1.1" ]; then
		echo "yes"
		return
	fi

	echo "no"
}

set_permissions()
{
	if [ x$(is_target_device $1) = xyes ]; then
		chgrp $new_group /dev/"${2}".*
		chmod $new_perms /dev/"${2}".*
		#
		# We need to create a symlink here to remember
		# the ugen device node that was used, since we
		# can't recover it from the device name that
		# comes from the kernel later because we get the
		# event *after* the device is gone, and thus
		# cannot query any properties.
		#
		rm -f /dev/${1}-${device_name}
		ln -sf ${2} /dev/${1}-${device_name}
	fi
}

restore_permissions()
{
	if [ -h "/dev/${1}-${device_name}" ]; then
		devnode=$(readlink "/dev/${1}-${device_name}")
		if [ x"$devnode" != x ]; then
			chmod $orig_perms /dev/"${devnode}".*
			chgrp $orig_group /dev/"${devnode}".*
		fi
		rm -f "/dev/${1}-${device_name}"
	fi
}

get_ugen_devnode()
{
	# Because "ugen" and "ugenif" share the same /dev/ugenN.*
	# namespace, we have to query an additional property to
	# determine which one it is.
	local ugen_unit

	ugen_unit=$(drvctl -p $1 ugen-unit)
	case "$ugen_unit" in
	[0-9]*)
		echo "ugen$ugen_unit"
		;;
	esac
}

for device in $devices; do
	case $device in
	ugensa*)
		# Ignore ugensa(4).
		;;
	ugen*)
		case $event in
		device-attach)
			devnode=$(get_ugen_devnode $1)
			if [ x"$devnode" != x ]; then
				set_permissions $device $devnode
			fi
			;;
		device-detach)
			restore_permissions $device
			;;
		esac
	esac
done
@