working init for squashfs boot

build.sh

@@ -84,6 +84,7 @@ echo "copying data into the image"
 populate_partitions $image_loop $initramfs_dir $rootfs_dir
 
 echo "cleaning up loop devices"
+umount $rootfs_dir
 losetup -d $shim_loop
 losetup -d $image_loop
 echo "done"

build_rootfs.sh

@@ -50,7 +50,7 @@ for mountpoint in $chroot_mounts; do
   mount --make-rslave --rbind "/${mountpoint}" "${rootfs_dir}/$mountpoint"
 done
 
-chroot_command="DEBUG=${DEBUG} release_name=${release_name} packages=${packages} /opt/setup_rootfs.sh"
+chroot_command="/opt/setup_rootfs.sh '$DEBUG' '$release_name' '$packages'"
 chroot $rootfs_dir /bin/bash -c "${chroot_command}"
 
 for mountpoint in $chroot_mounts; do

build_squashfs.sh

@@ -35,14 +35,16 @@ compile_unionfs() {
 
   local repo_url="https://github.com/rpodgorny/unionfs-fuse"
   local original_dir="$(pwd)"
+  local core_count="$(nproc --all)"
   
   rm -rf $working_path
   git clone $repo_url -b master --depth=1 $working_path
   cd $working_path
 
-  env LDFLAGS="-static" make
+  env LDFLAGS="-static" make -j$core_count
   local binary_path="$working_path/src/unionfs"
   cp $binary_path $out_path
+  cd $original_dir
 }
 
 rootfs_dir=$(realpath $1)
@@ -67,7 +69,7 @@ rm -rf $kernel_dir
 mkdir $kernel_dir -p
 dd if=$kernel_loop of=$kernel_dir/kernel.bin bs=1M status=progress
 
-echo "extracting initramfs from kernel"
+echo "extracting initramfs from kernel (this may take a while)"
 extract_initramfs $kernel_dir/kernel.bin $kernel_dir $rootfs_dir
 rm -rf $rootfs_dir/init
 
@@ -75,16 +77,12 @@ echo "mounting shim"
 make_mountable "${shim_loop}p3"
 safe_mount "${shim_loop}p3" $shim_rootfs
 
-echo "extracting and compressing modules from shim"
-extract_modules $modules_squashfs $shim_rootfs
-
 echo "compressing old rootfs"
 mksquashfs $old_dir $root_squashfs -noappend -comp gzip
 
 echo "patching new rootfs"
 mv $unionfs_dir/unionfs $rootfs_dir/bin/unionfs
-#cp -ar ./squashfs/* $rootfs_dir/
+cp -ar squashfs/* $rootfs_dir/
+chmod +x $rootfs_dir/bin/*
 
-echo "cleaning up"
+echo "done"
-umount $shim_rootfs
-losetup -d $shim_loop

rootfs/opt/setup_rootfs.sh

@@ -3,6 +3,10 @@
 #setup the debian rootfs
 #this is meant to be run within the chroot created by debootstrap
 
+DEBUG="$1"
+release_name="$2"
+packages="$3"
+
 set -e
 if [ "$DEBUG" ]; then
   set -x
@@ -23,13 +27,14 @@ END
 #install the patched systemd
 apt-get install -y ca-certificates
 apt-get update
-apt-get upgrade -y 
+installed_systemd="$(dpkg-query -W -f='${binary:Package}\n' | grep "systemd")"
+apt-get install --reinstall $installed_systemd
 
 #enable shimboot services
 systemctl enable kill-frecon.service
 
 #install desktop
-apt-get install -y task-xfce-desktop cloud-utils zram-tools
+apt-get install -y $packages cloud-utils zram-tools
 
 #set up zram
 tee -a /etc/default/zramswap << END

shim_utils.sh

@@ -23,10 +23,3 @@ extract_initramfs() {
   rm -rf $output_dir
   cat $cpio_path | cpio -D $output_dir -imd --quiet
 }
-
-extract_modules() {
-  local output_path="$1"
-  local shim_rootfs="$2"
-  local modules_dir="$shim_rootfs/lib/modules"
-  mksquashfs $modules_dir $output_path -noappend -comp gzip
-}

squashfs/bin/bootstrap.sh

@@ -0,0 +1,68 @@
+#!/bin/busybox sh
+
+#mount the squashfs + unionfs and boot into it
+
+move_mounts() {
+  local base_mounts="/sys /proc /dev"
+  local newroot_mnt="$1"
+  for mnt in $base_mounts; do
+    mkdir -p "$newroot_mnt$mnt"
+    mount -n -o move "$mnt" "$newroot_mnt$mnt"
+  done
+}
+
+boot_dir() {
+  local target="$1"
+
+  echo "moving mounts to newroot"
+  move_mounts $target
+
+  echo "switching root"
+  mkdir -p $target/oldroot
+  pivot_root $target $target/oldroot
+
+  /bin/bash -c "mount -o bind /oldroot/lib/modules /lib/modules"
+  exec /sbin/init < "$TTY1" >> "$TTY1" 2>&1
+}
+
+mount_squashfs() {
+  mkdir -p /lib/modules /mnt/root_squashfs
+  mount /root.squashfs /mnt/root_squashfs
+  mount -o bind /mnt/root_squashfs/lib/modules /lib/modules
+}
+
+#based on https://github.com/rpodgorny/unionfs-fuse/blob/master/examples/S01a-unionfs-live-cd.sh
+mount_unionfs() {
+  local chroot_path="/tmp/unionfs"
+  local data_path="/data"
+  local mountpoint="/newroot"
+  local squashfs_path="/mnt/root_squashfs"
+
+  local fuse_options="-o allow_other,suid,dev"
+  local unionfs_options="-o cow,chroot=$chroot_path,max_files=32768"
+
+  mkdir -p $data_path 
+  mkdir -p $mountpoint
+  mkdir -p $chroot_path/root
+  mkdir -p $chroot_path/rw
+  
+  mount -o bind $squashfs_path $chroot_path/root
+  mount -o bind $data_path $chroot_path/rw
+
+  modprobe fuse
+  unionfs $fuse_options $unionfs_options /root=RO:/rw=RW /newroot
+}
+
+main() {
+  echo "mounting squashfs"
+  mount_squashfs
+
+  echo "mounting unionfs"
+  mount_unionfs
+
+  echo "booting unionfs"
+  boot_dir /newroot
+}
+
+main "$@"
+sleep 1d

squashfs/bin/init

@@ -0,0 +1,29 @@
+#!/bin/busybox sh
+
+#original: https://chromium.googlesource.com/chromiumos/platform/initramfs/+/refs/heads/main/factory_shim/init
+
+detect_tty() {
+  if [ -f "/bin/frecon-lite" ]; then
+    export TTY1="/dev/pts/0"
+    export TTY2="/dev/pts/1"
+  else
+    export TTY1="/dev/tty1"
+    export TTY2="/dev/tty2"
+  fi
+}
+
+setup_environment() {
+  # Install additional utility programs.
+  /bin/busybox --install /bin || true
+}
+
+main() {
+  setup_environment
+  detect_tty
+  # In case an error is not handled by bootstrapping, stop here
+  # so that an operator can see installation stop.
+  exec bootstrap.sh < "$TTY1" >> "$TTY1" 2>&1 || sleep 1d
+}
+
+main "$@"
+exit 1