From ce65df3a3643706f27ed21fecf973ce0600ed386 Mon Sep 17 00:00:00 2001
From: Patrick Hilhorst <git@hilhorst.be>
Date: Tue, 6 Nov 2018 17:32:54 +0100
Subject: [PATCH] nixos-generate-config: fix for swapless kernels

Fixes #49826
---
 .../installer/tools/nixos-generate-config.pl     | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/nixos/modules/installer/tools/nixos-generate-config.pl b/nixos/modules/installer/tools/nixos-generate-config.pl
index b70faa380e54..52a129b39bcd 100644
--- a/nixos/modules/installer/tools/nixos-generate-config.pl
+++ b/nixos/modules/installer/tools/nixos-generate-config.pl
@@ -314,14 +314,16 @@ push @attrs, "services.xserver.videoDrivers = [ \"$videoDriver\" ];" if $videoDr
 
 # Generate the swapDevices option from the currently activated swap
 # devices.
-my @swaps = read_file("/proc/swaps");
-shift @swaps;
+my @swaps = read_file("/proc/swaps", err_mode => 'carp');
 my @swapDevices;
-foreach my $swap (@swaps) {
-    $swap =~ /^(\S+)\s/;
-    next unless -e $1;
-    my $dev = findStableDevPath $1;
-    push @swapDevices, "{ device = \"$dev\"; }";
+if (@swaps) {
+    shift @swaps;
+    foreach my $swap (@swaps) {
+        $swap =~ /^(\S+)\s/;
+        next unless -e $1;
+        my $dev = findStableDevPath $1;
+        push @swapDevices, "{ device = \"$dev\"; }";
+    }
 }