2 files changed, 51 insertions, 0 deletions
diff --git a/lib/default.nix b/lib/default.nix
index f720a08..0a99f97 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -42,6 +42,23 @@ let {
     in
       flatten [] (source.${source.type}.inputs or {});
 
+    # Tells whether a source's inputs get drawn from other sources by a
+    # generated flake in .populate/flakes, instead of by rewriting the lock
+    # file of the flake in the source.  Symlink sources point at other
+    # sources, whose lock files stay as they are.
+    hasGeneratedFlake = source:
+      lib.flakeFollows source != [] &&
+      (source.type == "symlink" || !(source.${source.type}.rewriteLock or true));
+
+    # Tells whether a flake or flake-input source gets delivered as a copy,
+    # which gets patched, gets its lock file rewritten, or is materialized.
+    derivesFlake = source: let
+      source' = source.${source.type};
+    in
+      lib.elem source.type [ "flake" "flake-input" ] &&
+      (source'.materialize or false || source'.patches or [] != [] ||
+       (source'.rewriteLock or true && lib.flakeFollows source != []));
+
     maybeHostName = default: let
       # We're parsing /etc/hostname here because reading
       # /proc/sys/kernel/hostname yields ""
diff --git a/lib/types/populate.nix b/lib/types/populate.nix
index 4523dad..a278ffd 100644
--- a/lib/types/populate.nix
+++ b/lib/types/populate.nix
@@ -125,6 +125,10 @@
         path = lib.mkOption {
           type = lib.types.absolute-pathname;
         };
+        rewriteLock = lib.mkOption {
+          default = true;
+          type = lib.types.bool;
+        };
         useChecksum = lib.mkOption {
           default = false;
           type = lib.types.bool;
@@ -185,6 +189,19 @@
           default = {};
           type = flake-inputs;
         };
+        materialize = lib.mkOption {
+          default = false;
+          type = lib.types.bool;
+        };
+        patches = lib.mkOption {
+          apply = map toString;
+          default = [];
+          type = lib.types.listOf lib.types.path;
+        };
+        rewriteLock = lib.mkOption {
+          default = true;
+          type = lib.types.bool;
+        };
       };
     };
     flake-input = lib.types.submodule {
@@ -200,6 +217,19 @@
           default = {};
           type = flake-inputs;
         };
+        materialize = lib.mkOption {
+          default = false;
+          type = lib.types.bool;
+        };
+        patches = lib.mkOption {
+          apply = map toString;
+          default = [];
+          type = lib.types.listOf lib.types.path;
+        };
+        rewriteLock = lib.mkOption {
+          default = true;
+          type = lib.types.bool;
+        };
         name = lib.mkOption {
           type = lib.types.str;
         };
@@ -224,6 +254,10 @@
         ref = lib.mkOption {
           type = lib.types.str; # TODO lib.types.git.ref
         };
+        rewriteLock = lib.mkOption {
+          default = true;
+          type = lib.types.bool;
+        };
         url = lib.mkOption {
           type = lib.types.str; # TODO lib.types.git.url
         };