nixos/sks: Fix another regression from ab5dcc7068b

The two directories KDB and PTree do not exist before the SKS DB is
build for the first time. If /var/db/sks is empty and the module is
enabled via "services.sks.enable = true;" the following error will
occur:
...-unit-script-sks-db-pre-start[xxx]:
ln: failed to create symbolic link 'KDB/DB_CONFIG': No such file or directory

To avoid this both links have to be created after the DB is build.
Note: Creating the directories manually might be better but the initial
build might be skipped as a result:
unit-script-sks-db-pre-start[xxxxx]: KeyDB directory already exists.  Exiting.
unit-script-sks-db-pre-start[xxxxx]: PTree directory already exists.  Exiting.

1 files changed, 13 insertions, 11 deletions

diff --git a/nixos/modules/services/security/sks.nix b/nixos/modules/services/security/sks.nix
index 2d717ac9474..1b7a2ad1398 100644
--- a/nixos/modules/services/security/sks.nix
+++ b/nixos/modules/services/security/sks.nix
@@ -116,20 +116,22 @@ in {
           ${lib.optionalString (cfg.webroot != null)
             "ln -sfT \"${cfg.webroot}\" web"}
           mkdir -p dump
-          # Check that both database configs are symlinks before overwriting them
-          if [ -e KDB/DB_CONFIG ] && [ ! -L KDB/DB_CONFIG ]; then
-            echo "KDB/DB_CONFIG exists but is not a symlink." >&2
-            exit 1
-          fi
-          if [ -e PTree/DB_CONFIG ] && [ ! -L PTree/DB_CONFIG ]; then
-            echo "PTree/DB_CONFIG exists but is not a symlink." >&2
-            exit 1
-          fi
-          ln -sf ${dbConfig} KDB/DB_CONFIG
-          ln -sf ${dbConfig} PTree/DB_CONFIG
           ${sksPkg}/bin/sks build dump/*.gpg -n 10 -cache 100 || true #*/
           ${sksPkg}/bin/sks cleandb || true
           ${sksPkg}/bin/sks pbuild -cache 20 -ptree_cache 70 || true
+          # Check that both database configs are symlinks before overwriting them
+          # TODO: The initial build will be without DB_CONFIG, but this will
+          # hopefully not cause any significant problems. It might be better to
+          # create both directories manually but we have to check that this does
+          # not affect the initial build of the DB.
+          for CONFIG_FILE in KDB/DB_CONFIG PTree/DB_CONFIG; do
+            if [ -e $CONFIG_FILE ] && [ ! -L $CONFIG_FILE ]; then
+              echo "$CONFIG_FILE exists but is not a symlink." >&2
+              echo "Please remove $PWD/$CONFIG_FILE manually to continue." >&2
+              exit 1
+            fi
+            ln -sf ${dbConfig} $CONFIG_FILE
+          done
         '';
         serviceConfig = {
           WorkingDirectory = "~";