From 5c9319ddac964ae78d947a47b3f0b36fd0efda51 Mon Sep 17 00:00:00 2001
From: Wout Mertens <Wout.Mertens@gmail.com>
Date: Wed, 18 Feb 2015 01:08:03 +0100
Subject: [PATCH] writeTextFile: Use passAsFile if available

---
 pkgs/build-support/trivial-builders.nix | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pkgs/build-support/trivial-builders.nix b/pkgs/build-support/trivial-builders.nix
index 78e671e8d229..7e73f98db782 100644
--- a/pkgs/build-support/trivial-builders.nix
+++ b/pkgs/build-support/trivial-builders.nix
@@ -20,13 +20,18 @@ rec {
     }:
     runCommand name
       { inherit text executable;
+        passAsFile = [ "text" ];
         # Pointless to do this on a remote machine.
         preferLocalBuild = true;
       }
       ''
         n=$out${destination}
         mkdir -p "$(dirname "$n")"
-        echo -n "$text" > "$n"
+        if [ -e "$textPath" ]; then
+          mv "$textPath" "$n"
+        else
+          echo -n "$text" > "$n"
+        fi
         (test -n "$executable" && chmod +x "$n") || true
       '';