From f0b4a5da478003f11da0aaaa38be02afacd4e4d9 Mon Sep 17 00:00:00 2001
From: Shamrock Lee <44064051+ShamrockLee@users.noreply.github.com>
Date: Mon, 11 Jul 2022 01:48:19 +0800
Subject: [PATCH] voms: default to symlink $out/etc to /etc

---
 pkgs/tools/networking/voms/default.nix | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/pkgs/tools/networking/voms/default.nix b/pkgs/tools/networking/voms/default.nix
index 2dd5643e740..a16648b9a83 100644
--- a/pkgs/tools/networking/voms/default.nix
+++ b/pkgs/tools/networking/voms/default.nix
@@ -11,6 +11,10 @@
 , gsoap
 , openssl
 , zlib
+  # Configuration overridable with .override
+  # If not null, the builder will
+  # move "$out/etc" to "$out/etc.orig" and symlink "$out/etc" to externalEtc.
+, externalEtc ? "/etc"
 }:
 
 stdenv.mkDerivation rec{
@@ -24,6 +28,10 @@ stdenv.mkDerivation rec{
     hash = "sha256-FG4fHO2lsQ3t/ZaKT9xY+xqdQHfdtzi5ULtxLhdPnss=";
   };
 
+  passthru = {
+    inherit externalEtc;
+  };
+
   nativeBuildInputs = [
     autoreconfHook
     bison
@@ -59,6 +67,13 @@ stdenv.mkDerivation rec{
     "--with-gsoap-wsdl2h=${gsoap}/bin/wsdl2h"
   ];
 
+  postFixup = ''
+    ${lib.optionalString (externalEtc != null) ''
+      mv "$out"/etc{,.orig}
+      ln -s ${lib.escapeShellArg externalEtc} "$out/etc"
+    ''}
+  '';
+
   meta = with lib; {
     description = "The C/C++ VOMS server, client and APIs v2.x";
     homepage = "https://italiangrid.github.io/voms/";