From e399ef002e9372cc7f2946b59d4f30e0ee8e9ef2 Mon Sep 17 00:00:00 2001
From: ading2210 <ading2019@gmail.com>
Date: Wed, 20 Dec 2023 22:48:32 -0800
Subject: [PATCH] extract modules to squashfs

---
 build_squashfs.sh | 72 ++++++++++++++++++++++++++++++++++++++++++++++-
 shim_utils.sh     |  7 +++++
 2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/build_squashfs.sh b/build_squashfs.sh
index 6e1f508..c7fc630 100755
--- a/build_squashfs.sh
+++ b/build_squashfs.sh
@@ -5,6 +5,76 @@
 # - FUSE kernel modules from the shim
 # - unionfs-fuse statically compiled 
 # - the main squashfs, compressed with gzip
+#this script is currently incomplete
 
+set -e
+if [ "$DEBUG" ]; then
+  set -x
+fi
 
-#todo - gotta refactor the other build scripts first
\ No newline at end of file
+. ./image_utils.sh
+. ./shim_utils.sh
+
+print_help() {
+  echo "Usage: ./build_squashfs.sh rootfs_dir uncompressed_rootfs_dir path_to_shim"
+}
+
+if [ "$EUID" -ne 0 ]; then
+  echo "this needs to be run as root."
+  exit 1
+fi
+
+if [ -z "$3" ]; then
+  print_help
+  exit 1
+fi
+
+compile_unionfs() {
+  local out_path="$1"
+  local working_path="$2"
+
+  local repo_url="https://github.com/rpodgorny/unionfs-fuse"
+  local original_dir="$(pwd)"
+  
+  rm -rf $working_path
+  git clone $repo_url -b master --depth=1 $working_path
+  cd $working_path
+
+  env LDFLAGS="-static" make
+  local binary_path="$working_path/src/unionfs"
+  cp $binary_path $out_path
+}
+
+rootfs_dir=$(realpath $1)
+target_dir=$(realpath $2)
+shim_path=$(realpath $3)
+
+shim_rootfs="/tmp/shim_rootfs"
+modules_squashfs="/tmp/modules.squashfs"
+kernel_dir=/tmp/shim_kernel
+initramfs_dir=/tmp/shim_initramfs
+
+echo "compiling unionfs-fuse"
+compile_unionfs /tmp/unionfs /tmp/unionfs-fuse 
+
+echo "mounting shim"
+shim_loop=$(create_loop "${shim_path}")
+make_mountable "${shim_loop}p3"
+safe_mount "${shim_loop}p3" $shim_rootfs
+
+echo "extracting modules from shim"
+extract_modules $modules_squashfs $shim_rootfs
+
+echo "copying shim kernel"
+mkdir $kernel_dir -p
+kernel_loop="${shim_loop}p2"
+dd if=$kernel_loop of=$kernel_dir/kernel.bin bs=1M status=none
+
+echo "extracting initramfs from kernel"
+extract_initramfs $kernel_dir/kernel.bin $kernel_dir $rootfs_dir
+
+#todo...
+
+echo "cleaning up"
+umount $shim_rootfs
+losetup -d $shim_loop
\ No newline at end of file
diff --git a/shim_utils.sh b/shim_utils.sh
index e2e5582..704e27b 100755
--- a/shim_utils.sh
+++ b/shim_utils.sh
@@ -22,4 +22,11 @@ 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
 }
\ No newline at end of file