onion-addresses: fix files not being copied

When NixOS is already running and Tor is restarted due to config
changes, `/var/lib/tor/state` may be present even when Tor has not
yet finished setting up onion services.
This caused the previous version of `onion-addresses` to not wait for
Tor and to skip not yet present onion service files.

`onion-addresses` now waits until each required onion service file
has appeared.

modules/onion-addresses.nix

@@ -58,8 +58,20 @@ in {
         CapabilityBoundingSet = "CAP_CHOWN CAP_FSETID CAP_SETFCAP CAP_DAC_OVERRIDE CAP_DAC_READ_SEARCH CAP_FOWNER CAP_IPC_OWNER";
       };
       script = ''
+        waitForFile() {
+          file=$1
+          for ((i=0; i<300; i++)); do
+            if [[ -e $file ]]; then
+              return;
+            fi
+            sleep 0.1
+          done
+          echo "Error: File $file did not appear after 30 sec."
+          exit 1
+        }
+
         # Wait until tor is up
-        until [[ -e /var/lib/tor/state ]]; do sleep 0.1; done
+        waitForFile /var/lib/tor/state
 
         cd ${cfg.dataDir}
         rm -rf *
@@ -71,10 +83,9 @@ in {
             ${concatMapStrings
               (service: ''
                 onionFile=/var/lib/tor/onion/${service}/hostname
-                if [[ -e $onionFile ]]; then
+                waitForFile $onionFile
                 cp $onionFile ${user}/${service}
                 chown ${user} ${user}/${service}
-                fi
               '')
               cfg.access.${user}
              }
@@ -84,9 +95,8 @@ in {
 
         ${concatMapStrings (service: ''
           onionFile=/var/lib/tor/onion/${service}/hostname
-          if [[ -e $onionFile ]]; then
+          waitForFile $onionFile
           install -D -o ${config.systemd.services.${service}.serviceConfig.User} -m 400 $onionFile services/${service}
-          fi
         '') cfg.services}
       '';
     };