From 0a367c41ea2b956b7952e1e81da6d51e95a310cd Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Wed, 28 Nov 2018 19:09:02 -0500
Subject: [PATCH] iso-image: Verifies the FAT partition at build.

This is done to ensure `mtools`-based operations leave a clean FS.
---
 nixos/modules/installer/cd-dvd/iso-image.nix | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/nixos/modules/installer/cd-dvd/iso-image.nix b/nixos/modules/installer/cd-dvd/iso-image.nix
index 96fdb997b2c0..dbf7643c3369 100644
--- a/nixos/modules/installer/cd-dvd/iso-image.nix
+++ b/nixos/modules/installer/cd-dvd/iso-image.nix
@@ -340,6 +340,8 @@ let
       truncate --size=$image_size "$out"
       ${pkgs.libfaketime}/bin/faketime "2000-01-01 00:00:00" ${pkgs.dosfstools}/sbin/mkfs.vfat -i 12345678 -n EFIBOOT "$out"
       mcopy -bpsvm -i "$out" ./* ::
+      # Verify the FAT partition.
+      ${pkgs.dosfstools}/sbin/fsck.vfat -vn "$out"
     ''; # */
 
   targetArch = if pkgs.stdenv.isi686 then