environment.etc: add user/group option

fixes #27546

nixos/modules/config/users-groups.nix

@@ -527,7 +527,7 @@ in {
       input.gid = ids.gids.input;
     };
 
-    system.activationScripts.users = stringAfter [ "etc" ]
+    system.activationScripts.users = stringAfter [ "stdio" ]
       ''
         ${pkgs.perl}/bin/perl -w \
           -I${pkgs.perlPackages.FileSlurp}/lib/perl5/site_perl \

nixos/modules/system/etc/etc.nix

@@ -20,8 +20,8 @@ let
     sources = map (x: x.source) etc';
     targets = map (x: x.target) etc';
     modes = map (x: x.mode) etc';
-    uids  = map (x: x.uid) etc';
-    gids  = map (x: x.gid) etc';
+    users  = map (x: x.user) etc';
+    groups  = map (x: x.group) etc';
   };
 
 in
@@ -108,6 +108,26 @@ in
               '';
             };
 
+            user = mkOption {
+              default = "+${toString config.uid}";
+              type = types.str;
+              description = ''
+                User name of created file.
+                Only takes affect when the file is copied (that is, the mode is not 'symlink').
+                Changing this option takes precedence over <literal>uid</literal>.
+              '';
+            };
+
+            group = mkOption {
+              default = "+${toString config.gid}";
+              type = types.str;
+              description = ''
+                Group name of created file.
+                Only takes affect when the file is copied (that is, the mode is not 'symlink').
+                Changing this option takes precedence over <literal>gid</literal>.
+              '';
+            };
+
           };
 
           config = {
@@ -130,7 +150,7 @@ in
 
     system.build.etc = etc;
 
-    system.activationScripts.etc = stringAfter [ "stdio" ]
+    system.activationScripts.etc = stringAfter [ "users" "groups" ]
       ''
         # Set up the statically computed bits of /etc.
         echo "setting up /etc..."

nixos/modules/system/etc/make-etc.sh

@@ -6,8 +6,8 @@ set -f
 sources_=($sources)
 targets_=($targets)
 modes_=($modes)
-uids_=($uids)
-gids_=($gids)
+users_=($users)
+groups_=($groups)
 set +f
 
 for ((i = 0; i < ${#targets_[@]}; i++)); do
@@ -36,9 +36,9 @@ for ((i = 0; i < ${#targets_[@]}; i++)); do
         fi
         
         if test "${modes_[$i]}" != symlink; then
-            echo "${modes_[$i]}" > $out/etc/$target.mode
-            echo "${uids_[$i]}" > $out/etc/$target.uid
-            echo "${gids_[$i]}" > $out/etc/$target.gid
+            echo "${modes_[$i]}"  > $out/etc/$target.mode
+            echo "${users_[$i]}"  > $out/etc/$target.uid
+            echo "${groups_[$i]}" > $out/etc/$target.gid
         fi
         
     fi

nixos/modules/system/etc/setup-etc.pl

@@ -108,6 +108,8 @@ sub link {
             my $uid = read_file("$_.uid"); chomp $uid;
             my $gid = read_file("$_.gid"); chomp $gid;
             copy "$static/$fn", "$target.tmp" or warn;
+            $uid = getpwnam $uid unless $uid =~ /^\+/;
+            $gid = getgrnam $gid unless $gid =~ /^\+/;
             chown int($uid), int($gid), "$target.tmp" or warn;
             chmod oct($mode), "$target.tmp" or warn;
             rename "$target.tmp", $target or warn;