From fd0fd49d36bc713b3783686a4a41f4680f874c4d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Fri, 11 Oct 2013 14:44:32 +0200
Subject: [PATCH] nixos-generate-config: Write to /etc/nixos/hardware.nix
 rather than stdout

---
 .../installer/tools/nixos-generate-config.pl  | 44 +++++++++++++++----
 nixos/modules/installer/tools/tools.nix       |  5 ++-
 2 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/nixos/modules/installer/tools/nixos-generate-config.pl b/nixos/modules/installer/tools/nixos-generate-config.pl
index 3204f3d40512..58508560b8e4 100644
--- a/nixos/modules/installer/tools/nixos-generate-config.pl
+++ b/nixos/modules/installer/tools/nixos-generate-config.pl
@@ -1,7 +1,28 @@
-#! @perl@/bin/perl -w
+#! @perl@
 
 use File::Spec;
+use File::Path;
 use File::Basename;
+use File::Slurp;
+
+
+# Process the command line.
+my $outDir = "/etc/nixos";
+
+for (my $n = 0; $n < scalar @ARGV; $n++) {
+    my $arg = $ARGV[$n];
+    if ($arg eq "--help") {
+        exec "man nixos-generate-config" or die;
+    }
+    elsif ($arg eq "--dir") {
+        $n++;
+        $outDir = $ARGV[$n];
+        die "$0: ‘--dir’ requires an argument\n" unless defined $outDir;
+    }
+    else {
+        die "$0: unrecognized argument ‘$arg’\n";
+    }
+}
 
 
 my @attrs = ();
@@ -62,13 +83,13 @@ sub pciCheck {
     my $vendor = readFile "$path/vendor";
     my $device = readFile "$path/device";
     my $class = readFile "$path/class";
-    
+
     my $module;
     if (-e "$path/driver/module") {
         $module = basename `readlink -f $path/driver/module`;
         chomp $module;
     }
-    
+
     debug "$path: $vendor $device $class";
     debug " $module" if defined $module;
     debug "\n";
@@ -140,11 +161,11 @@ sub usbCheck {
         $module = basename `readlink -f $path/driver/module`;
         chomp $module;
     }
-    
+
     debug "$path: $class $subclass $protocol";
     debug " $module" if defined $module;
     debug "\n";
- 
+
     if (defined $module) {
         if (# Mass-storage controller.  Definitely important.
             $class eq "08" ||
@@ -191,7 +212,7 @@ if ($dmi =~ /Manufacturer: innotek/) {
 }
 
 
-# Generate the configuration file.
+# Generate the hardware configuration file.
 
 sub removeDups {
     my %seen;
@@ -229,10 +250,14 @@ my $modulePackages = toNixExpr(removeDups @modulePackages);
 my $attrs = multiLineList("  ", removeDups @attrs);
 my $imports = multiLineList("    ", removeDups @imports);
 
+my $fn = "$outDir/hardware.nix";
+print STDERR "writing $fn...\n";
+mkpath($outDir, 0, 0755);
 
-print <<EOF ;
-# This is a generated file.  Do not modify!
-# Make changes to /etc/nixos/configuration.nix instead.
+write_file($fn, <<EOF);
+# Do not modify this file!  It was generated by ‘nixos-generate-config’
+# and may be overwritten by future invocations.  Please make changes
+# to /etc/nixos/configuration.nix instead.
 { config, pkgs, ... }:
 
 {
@@ -245,4 +270,5 @@ print <<EOF ;
   nix.maxJobs = $cpus;
 $attrs}
 EOF
+
 # workaround for a bug in substituteAll
diff --git a/nixos/modules/installer/tools/tools.nix b/nixos/modules/installer/tools/tools.nix
index dd680f0f6fca..074c77b51467 100644
--- a/nixos/modules/installer/tools/tools.nix
+++ b/nixos/modules/installer/tools/tools.nix
@@ -1,5 +1,5 @@
 # This module generates nixos-install, nixos-rebuild,
-# nixos-hardware-scan, etc.
+# nixos-generate-config, etc.
 
 { config, pkgs, modulesPath, ... }:
 
@@ -37,7 +37,8 @@ let
   nixos-generate-config = makeProg {
     name = "nixos-generate-config";
     src = ./nixos-generate-config.pl;
-    inherit (pkgs) perl dmidecode;
+    perl = "${pkgs.perl}/bin/perl -I${pkgs.perlPackages.FileSlurp}/lib/perl5/site_perl";
+    inherit (pkgs) dmidecode;
   };
 
   nixos-option = makeProg {