Add script to build asahi-installer package from image

make-asahi-installer-package.sh

@@ -0,0 +1,52 @@
+#!/bin/sh
+
+set -eu
+
+fail() {
+  echo $* >&2
+  exit 1
+}
+
+requireCommands() {
+  for cmd in $*; do
+    if ! command -v $cmd &> /dev/null; then
+      fail "Cannot find required command: $cmd"
+    fi
+  done
+}
+
+[ "$#" -ne 2 ] && fail "usage: $0 <image> <package>"
+image="$1"
+package="$2"
+
+if [ ! -r "$image" ]; then
+  fail "$image does not exist or cannot be read!"
+fi
+
+if [ -e "$package" ]; then
+  fail "$package already exists, aborting"
+fi
+
+requireCommands sfdisk awk fatcat zip
+
+workdir="$(mktemp -d)"
+trap 'rm -rf "$workdir"' EXIT
+
+basedir="$PWD"
+imagename="$(basename "$image")"
+imagedir="$(dirname "$image")"
+
+# extract filesystems from disk image
+pushd "$imagedir"
+eval "$(sfdisk -ql "$imagename" | awk "NR>=2 { printf \"dd if=${imagename} of=${workdir}/%s skip=%s count=%s\\n\", \$1, \$2, \$4 }")"
+popd
+
+# build package
+mkdir -p "${workdir}/package/esp"
+fatcat "${workdir}/${imagename}1" -x "${workdir}/package/esp"
+mv "${workdir}/${imagename}2" "${workdir}/package/boot.img"
+mv "${workdir}/${imagename}3" "${workdir}/package/root.img"
+
+pushd "${workdir}/package"
+zip -r "${basedir}/${package}" .
+popd