[PATCH v2 3/6] base-files: fwtool: implement compatibility check for images

[Paul Spooren]

On 14.07.20 04:28, Adrian Schmutzler wrote:
> We regularly encounter the situation that devices are subject to
> changes that will make them incompatible to previous versions.
> Removing SUPPORTED_DEVICES will not really be helpful in most of these
> cases, as this only helps after a rename.
>
> To solve this situation, this patchset introduces a compatibility
> version for devices. In this patch, the actual checks are implemented
> into fwtool_check_image():
>
> If an incompatible change is introduced, one can increase either
> the minor version (1.0->1.1) or the major version (1.0->2.0).
>
> Minor version increment:
> This will still allow sysupgrade, but require to reset config
> (-n or SAVE_CONFIG=0). If sysupgrade is called without -n, a
> corresponding message will be printed. If sysupgrade is called
> with -n, it will just pass, with supported devices being checked
> as usual. (Which will allow us to add back SUPPORTED_DEVICES for
> many cases.)
>
> Major version increment:
> This is meant for potential (rare) cases where sysupgrade is
> not possible at all, because it would break the device.
> In this case, a warning will be printed, and -n won't help.
What are those rare cases? I just can't think of anything where not even 
a clean sysupgrade would be possible. Would it mean to go back to stock 
firmware and then upgrade a 2.x version? If there isn't a scenario maybe 
a single integer is easier to handle than a pseudo float.
> If image check fails because of one of the versions parts not
> matching, the content of DEVICE_COMPAT_MESSAGE is printed in
> addition to the generic message (if set).
>
> For both cases, upgrade can still be forced with -F as usual.
>
> Signed-off-by: Adrian Schmutzler <freifunk at adrianschmutzler.de>
>
> ---
>
> Changes in v2:
> - Move compat check AFTER supported_devices check
> - Improve error messages
> ---
>   .../base-files/files/lib/upgrade/fwtool.sh    | 24 ++++++++++++++++++-
>   1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/package/base-files/files/lib/upgrade/fwtool.sh b/package/base-files/files/lib/upgrade/fwtool.sh
> index a0b3fb0a04..1807aecd6d 100644
> --- a/package/base-files/files/lib/upgrade/fwtool.sh
> +++ b/package/base-files/files/lib/upgrade/fwtool.sh
> @@ -44,13 +44,35 @@ fwtool_check_image() {
>   	}
>   
>   	device="$(cat /tmp/sysinfo/board_name)"
> +	devicecompat="$(uci -q get system. at system[0].compat_version)"
> +	[ -n "$devicecompat" ] || devicecompat="1.0"
> +
> +	json_get_var imagecompat compat_version
> +	json_get_var compatmessage compat_message
> +	[ -n "$imagecompat" ] || imagecompat="1.0"
>   
>   	json_select supported_devices || return 1
>   
>   	json_get_keys dev_keys
>   	for k in $dev_keys; do
>   		json_get_var dev "$k"
> -		[ "$dev" = "$device" ] && return 0
> +		if [ "$dev" = "$device" ]; then
> +			# major compat version -> no sysupgrade
> +			if [ "${devicecompat%.*}" != "${imagecompat%.*}" ]; then
> +				echo "The device is supported, but this image is incompatible for sysupgrade based on the image version ($devicecompat->$imagecompat)."
> +				[ -n "$compatmessage" ] && echo "$compatmessage"
> +				return 1
> +			fi
> +
> +			# minor compat version -> sysupgrade with -n required
> +			if [ "${devicecompat#.*}" != "${imagecompat#.*}" ] && [ "$SAVE_CONFIG" = "1" ]; then
> +				echo "The device is supported, but the config is incompatible to the new image ($devicecompat->$imagecompat). Please upgrade with -n."
I'd write "Please upgrade with -n to reset the device configuration"
> +				[ -n "$compatmessage" ] && echo "$compatmessage"
> +				return 1
> +			fi
> +
> +			return 0
> +		fi
>   	done
>   
>   	echo "Device $device not supported by this image"