#!/bin/bash
# joevt May 8, 2023

#10.4 Tiger to 10.13 High Sierra
kextload=kextload

# Later macOS versions
command -v kextutil > /dev/null && kextload=kextutil

getkextidentifier () {
	local thekextpath="$1"
	if [[ ! -f "$thekextpath/Contents/Info.plist" ]]; then
		echo "# Missing Info.plist." 1>&2
		return 1
	fi
	# Mac OS X 10.4 doesn't have PlistBuddy so just use perl
	perl -0777 -n -e 'if (m|<key>CFBundleIdentifier</key>\s*<string>(.+)</string>|) { print $1 }' "$thekextpath/Contents/Info.plist"
}

checkkext () {
	local thekextpath="$1"
	if [[ -d "$thekextpath" ]]; then
		if [[ -f "$thekextpath/Contents/Info.plist" ]]; then
			local kextname
			kextname="$(basename "$thekextpath")"
			if grep -q -E "\.kext$" <<< "$kextname"; then
				local kextidentifier=""
				kextidentifier="$(getkextidentifier "$thekextpath")"
				local theerr=$?
				if (( theerr == 0 )); then
					return 0
				else
					echo "# Missing CFBundleIdentifier." 1>&2
					return 1
				fi
			else
				echo "# That's not a kext." 1>&2
				return 1
			fi
		else
			echo "# Missing Info.plist." 1>&2
			return 1
		fi
	else
		echo "# Expected a kext package directory." 1>&2
		return 1
	fi
}

unloadkext () {
	local thekextpath="$1"
	checkkext "$thekextpath" || return 1
	local kextname
	kextname="$(basename "$thekextpath")"
	local kextidentifier
	kextidentifier="$(getkextidentifier "$thekextpath")"
	echo "# kextname: $kextname"
	echo "# kextidentifier: $kextidentifier"
	if ( kextstat 2> /dev/null | grep -q "$kextidentifier" ); then
		while : ; do
			echo "# Unloading ${kextname}."
			sudo kextunload -b "$kextidentifier"
			( kextstat 2> /dev/null | grep -q "$kextidentifier" ) || break
			sleep 1
		done
		echo "# Unloaded ${kextname}."
	else
		echo "# ${kextname} is not loaded."
	fi
}

checkkextpermissions () {
	local thekextpath="$1"
	checkkext "$thekextpath" || return 1
	badpermissions="$(find "$thekextpath" -exec ls -ld {} \; | sed -E '/drwxr-xr-x.* root *wheel /d ; /-rw.r-.r-..* root *wheel /d')"
	if (( $(printf "%s" "$badpermissions" | wc -l) == 0 )); then
		return 0
	fi
	echo "# Permissions are not correct for the following:" 1>&2
	echo "$badpermissions" 1>&2
	return 1
}

fixkextpermissions () {
	local thekextpath="$1"
	checkkext "$thekextpath" || return 1
	if checkkextpermissions "$thekextpath" 2> /dev/null ; then
		echo "# Permissions are good. No changes were required."
		return 0
	fi
	sudo chown -R root:wheel "$thekextpath"
	sudo find "$thekextpath" -type d -exec /bin/chmod 0755 {} \;
	sudo find "$thekextpath" -type f -exec /bin/chmod 0644 {} \;
	if checkkextpermissions "$thekextpath" 2> /dev/null ; then
		echo "# Fixed permissions."
		return 0
	fi
	echo "# Could not fix permissions." 1>&2
	return 1
}

loadkext () {
	local thekextpath="$1"
	checkkext "$thekextpath" || return 1
	local kextname
	kextname="$(basename "$thekextpath")"

	local kextloadpath
	if fixkextpermissions "$thekextpath" > /dev/null 2>&1 ; then
		kextloadpath="$thekextpath"
	else
		echo "# Cannot fix permissions. Will load kext from temporary directory." 1>&2
		local kexttmpdir
		kexttmpdir="$(mktemp -d /tmp/KextUtil_XXXXXXX)"
		kextloadpath="$kexttmpdir/$kextname"
		sudo cp -R "$thekextpath" "kextloadpath"
		if ! fixkextpermissions "kextloadpath" ; then
			return 1
		fi
	fi

	unloadkext "$kextloadpath"
	if ( sudo "$kextload" "$kextloadpath" ); then
		echo "# Loaded ${kextname}."
		return 0
	else
		echo "# $kextname was not loaded." 1>&2
		return 1
	fi
}

mountsystemrw () {
	mount | grep ' on / ' | grep -q 'read-only' && sudo mount -uw /
}

installkext () {
	local doload=0
	local dosystem=0
	while (( $# )); do
		if [[ "$1" == "-l" ]]; then
			doload=1
		elif [[ "$1" == "-s" ]]; then
			dosystem=1
		else
			break
		fi
		shift 1
	done

	local thekextpath="$1"
	checkkext "$thekextpath" || return 1

	local kextname
	kextname="$(basename "$thekextpath")"
	local kextinstalldir="/Library/Extensions"
	if ((dosystem)); then
		kextinstalldir="/System/Library/Extensions"
	fi
	local kextidentifier
	kextidentifier="$(getkextidentifier "$thekextpath")"

	if ((doload)); then
		# unloadkext will do these echo lines for us:
		# echo "# kextname: $kextname"
		# echo "# kextidentifier: $kextidentifier"
		unloadkext "$thekextpath"
	else
		echo "# kextname: $kextname"
		echo "# kextidentifier: $kextidentifier"
	fi

	local kexttmpdir
	kexttmpdir="$(mktemp -d /tmp/KextUtil_XXXXXXX)"
	kextloadpath="$kexttmpdir/$kextname"
	sudo cp -R "$thekextpath" "kextloadpath"
	if ! fixkextpermissions "kextloadpath" ; then
		return 1
	fi

	if [[ -d "/System/Library/Extensions/$kextname" ]]; then
		mountsystemrw
		sudo rm -R "/System/Library/Extensions/$kextname"
	fi
	if [[ -d "/Library/Extensions/$kextname" ]]; then
		sudo rm -R "/Library/Extensions/$kextname"
	fi
	if ((dosystem)); then
		mountsystemrw
	fi
	sudo mv "kextloadpath" "$kextinstalldir"
	if ((doload)); then
		sudo "$kextload" "$kextinstalldir/$kextname"
		kextstat 2> /dev/null | grep "$kextidentifier"
	fi
}

removekext () {
	local thekextpath="$1"
	checkkext "$thekextpath" || return 1
	if [[ -d "$thekextpath" ]]; then
		if [[ "$thekextpath" == /System/Library/* ]] ; then
			mountsystemrw
		fi
		sudo rm -R "$thekextpath"
	fi
}

rebuildkextcache () {
	sudo kextcache -i /
}