freshBootstrapTools.bootstrapTools: extract as a sort of package

pkgs/stdenv/linux/bootstrap-tools/default.nix

@@ -0,0 +1,35 @@
+{
+  lib,
+  libc,
+  config,
+  system,
+  bootstrapFiles,
+  isFromBootstrapFiles ? false,
+}:
+
+let
+  maybeDenoteProvenance = lib.optionalAttrs isFromBootstrapFiles {
+    passthru = {
+      inherit isFromBootstrapFiles;
+    };
+  };
+
+  maybeContentAddressed = lib.optionalAttrs config.contentAddressedByDefault {
+    __contentAddressed = true;
+    outputHashAlgo = "sha256";
+    outputHashMode = "recursive";
+  };
+
+  args = {
+    inherit system bootstrapFiles;
+    extraAttrs = maybeContentAddressed;
+  };
+  result =
+    if libc == "glibc" then
+      import ./glibc.nix args
+    else if libc == "musl" then
+      import ./musl.nix args
+    else
+      throw "unsupported libc";
+in
+result // maybeDenoteProvenance

pkgs/stdenv/linux/default.nix

@@ -139,14 +139,11 @@ let
 
 
   # Download and unpack the bootstrap tools (coreutils, GCC, Glibc, ...).
-  bootstrapTools = (import (if localSystem.libc == "musl" then ./bootstrap-tools/musl.nix else ./bootstrap-tools/glibc.nix) {
-    inherit system bootstrapFiles;
-    extraAttrs = lib.optionalAttrs config.contentAddressedByDefault {
-      __contentAddressed = true;
-      outputHashAlgo = "sha256";
-      outputHashMode = "recursive";
-    };
-  }) // { passthru.isFromBootstrapFiles = true; };
+  bootstrapTools = import ./bootstrap-tools {
+    inherit (localSystem) libc system;
+    inherit lib bootstrapFiles config;
+    isFromBootstrapFiles = true;
+  };
 
   getLibc = stage: stage.${localSystem.libc};
 

pkgs/stdenv/linux/make-bootstrap-tools.nix

@@ -49,26 +49,11 @@ rec {
 
   inherit (build) bootstrapFiles;
 
-  bootstrapTools =
-    let extraAttrs = lib.optionalAttrs
-      config.contentAddressedByDefault
-      {
-        __contentAddressed = true;
-        outputHashAlgo = "sha256";
-        outputHashMode = "recursive";
-      };
-    in
-    if (stdenv.hostPlatform.libc == "glibc") then
-    import ./bootstrap-tools/glibc.nix {
-      inherit (stdenv.buildPlatform) system; # Used to determine where to build
-      inherit bootstrapFiles extraAttrs;
-    }
-    else if (stdenv.hostPlatform.libc == "musl") then
-    import ./bootstrap-tools/musl.nix {
-      inherit (stdenv.buildPlatform) system; # Used to determine where to build
-      inherit bootstrapFiles extraAttrs;
-    }
-    else throw "unsupported libc";
+  bootstrapTools = import ./bootstrap-tools {
+    inherit (stdenv.buildPlatform) system; # Used to determine where to build
+    inherit (stdenv.hostPlatform) libc;
+    inherit lib bootstrapFiles config;
+  };
 
   test = pkgs.callPackage ./test-bootstrap-tools.nix {
     inherit bootstrapTools;