Mount old versions of home on omen

Signed-off-by: magic_rb <richard@brezak.sk>

nixos/systems/omen/impermenance.nix

@@ -85,6 +85,22 @@
     '';
   };
 
+  systemd.services."mount-old-homes" = {
+    description = "Mount old versions of home dataset";
+
+    wantedBy = [ "local-fs.target" ];
+    after = [ "local-fs.target" ];
+
+    script = ''
+      ${pkgs.rolling_datasets}/bin/mount_datasets "omen-ssd/ephemeral/home" "/home/.old"
+    '';
+
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = "yes";
+      TimeoutStartSec = "5m";
+    };
+  };
 
   systemd.services."home-manager-main-pre.service" = {
     description = "Home Manager environment prestart for main";

overlays/rolling_datasets/bin/mount_datasets

@@ -0,0 +1,18 @@
+# -*- mode: shell-script -*-
+
+source @out@/share/functions/get_old_datasets
+
+export "PATH=$PATH:@runtimePath@"
+
+if [[ "$#" != 2 ]] ; then
+    echo "This script requires precisely 2 arguments!"
+    exit 1
+fi
+
+dataset="$1"
+mountpoint="$2"
+
+while IFS="\n" read gen
+do
+    mountpoint -q "$mountpoint/$gen" || mount -o x-mount.mkdir -v -t zfs "$dataset/$gen" "$mountpoint/$gen"
+done <<< "$(get_old_datasets "$dataset")"

overlays/rolling_datasets/bin/roll_dataset

@@ -2,6 +2,8 @@
 
 source @out@/share/functions/get_old_datasets
 
+export "PATH=$PATH:@runtimePath@"
+
 if [[ "$#" != 3 ]] ; then
     echo "This script requires precisely 2 arguments!"
     exit 1

overlays/rolling_datasets/default.nix

@@ -53,9 +53,13 @@
           } ''
             mkdir -p $out/bin
             mkdir -p $out/share/functions
+            export runtimeShell=${prev.runtimeShell} \
+                   runtimePath=${prev.lib.makeBinPath (with prev; [ utillinux zfs ])}
 
             for binary in ${./bin}/* ; do
-              substituteAll "$binary" "$out/bin/$(basename "$binary")"
+              output_binary="$out/bin/$(basename "$binary")"
+              substituteAll "$binary" "$output_binary"
+              chmod +x "$output_binary"
             done
 
             for function in ${./functions}/* ; do

overlays/rolling_datasets/functions/get_old_datasets

@@ -2,5 +2,5 @@
 function get_old_datasets()
 {
   dataset="$1"
-  zfs list "$dataset" -t filesystem -r -H -o name | xargs -I {} ${final.runtimeShell} -c 'echo "$1" | rev | cut -f 1 -d "/" | rev' sh {} | grep -v "$dataset"
+  zfs list "$dataset" -t filesystem -r -H -o name | xargs -I {} @runtimeShell@ -c 'echo "$1" | rev | cut -f 1 -d "/" | rev' sh {} | grep -v "$(basename "$dataset")"
 }