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nixos/image/repart: assert maximum label length

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The maximum label length is specified by UEFI and enforced/asserted by
systemd-repart. This lets evaluation fail already and give the user
some more information about what's wrong.

Also warn when the suggested label length is exceeded. This serves as a
safety mechanism for using systemd-sysupdate style A/B updates where the
version number is encoded in the label and might not be incrementable
when the maximum label size is reached.
This commit is contained in:
nikstur 2024-04-08 16:12:31 +02:00
parent 4c397ea6de
commit ad19cee09c
1 changed files with 38 additions and 0 deletions
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38
nixos/modules/image/repart.nix
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@ -6,6 +6,8 @@
let
cfg = config.image.repart;
inherit (utils.systemdUtils.lib) GPTMaxLabelLength;
partitionOptions = {
options = {
storePaths = lib.mkOption {
@ -224,6 +226,42 @@ in
config = {
assertions = lib.mapAttrsToList (fileName: partitionConfig:
let
inherit (partitionConfig) repartConfig;
labelLength = builtins.stringLength repartConfig.Label;
in
{
assertion = repartConfig ? Label -> GPTMaxLabelLength >= labelLength;
message = ''
The partition label '${repartConfig.Label}'
defined for '${fileName}' is ${toString labelLength} characters long,
but the maximum label length supported by UEFI is ${toString
GPTMaxLabelLength}.
'';
}
) cfg.partitions;
warnings = lib.filter (v: v != null) (lib.mapAttrsToList (fileName: partitionConfig:
let
inherit (partitionConfig) repartConfig;
suggestedMaxLabelLength = GPTMaxLabelLength - 2;
labelLength = builtins.stringLength repartConfig.Label;
in
if (repartConfig ? Label && labelLength >= suggestedMaxLabelLength) then ''
The partition label '${repartConfig.Label}'
defined for '${fileName}' is ${toString labelLength} characters long.
The suggested maximum label length is ${toString
suggestedMaxLabelLength}.
If you use sytemd-sysupdate style A/B updates, this might
not leave enough space to increment the version number included in
the label in a future release. For example, if your label is
${toString GPTMaxLabelLength} characters long (the maximum enforced by UEFI) and
you're at version 9, you cannot increment this to 10.
'' else null
) cfg.partitions);
image.repart =
let
version = config.image.repart.version;