Mount unionfs-fuse filesystems using the normal fileSystems option

nixos/modules/system/boot/stage-1-init.sh

@@ -4,7 +4,8 @@ targetRoot=/mnt-root
 console=tty1
 
 export LD_LIBRARY_PATH=@extraUtils@/lib
-export PATH=@extraUtils@/bin:@extraUtils@/sbin
+export PATH=@extraUtils@/bin
+ln -s @extraUtils@/bin /bin
 
 
 fail() {
@@ -262,6 +263,13 @@ mountFS() {
 
     checkFS "$device" "$fsType"
 
+    # Create backing directories for unionfs-fuse.
+    if [ "$fsType" = unionfs-fuse ]; then
+        for i in $(IFS=:; echo ${options##*,dirs=}); do
+            mkdir -m 0700 -p /mnt-root"${i%=*}"
+        done
+    fi
+
     echo "mounting $device on $mountPoint..."
 
     mkdir -p "/mnt-root$mountPoint" || true

nixos/modules/system/boot/stage-1.nix

@@ -35,6 +35,7 @@ let
     }
     ''
       mkdir -p $out/bin $out/lib
+      ln -s $out/bin $out/sbin
 
       # Copy what we need from Glibc.
       cp -pv ${pkgs.glibc}/lib/ld*.so.? $out/lib
@@ -46,11 +47,10 @@ let
       cp -pv ${pkgs.gcc.gcc}/lib*/libgcc_s.so.* $out/lib
 
       # Copy BusyBox.
-      cp -rvd ${pkgs.busybox}/{bin,sbin} $out/
-      chmod -R u+w $out
+      cp -pvd ${pkgs.busybox}/bin/* ${pkgs.busybox}/sbin/* $out/bin/
 
       # Copy some utillinux stuff.
-      cp -v ${pkgs.utillinux}/sbin/blkid $out/bin
+      cp -vf ${pkgs.utillinux}/sbin/blkid $out/bin
       cp -pdv ${pkgs.utillinux}/lib/libblkid*.so.* $out/lib
       cp -pdv ${pkgs.utillinux}/lib/libuuid*.so.* $out/lib
 
@@ -73,7 +73,7 @@ let
 
       # Copy modprobe.
       cp -v ${pkgs.kmod}/bin/kmod $out/bin/
-      ln -s kmod $out/bin/modprobe
+      ln -sf kmod $out/bin/modprobe
 
       ${config.boot.initrd.extraUtilsCommands}