refactor(zbm): Add ZBM postconf hook (#3)

We're adding this to our chroot after we've
generated a ZBM UEFI image file /without/
this hook script. It's meant to run only in our real
OS.

setup.sh

@@ -18,6 +18,7 @@ exec 3>&1
 
 declare this_script_url
 this_script_url="${SCRIPT_URL:?}"
+postconf_hook="$(dirname "${this_script_url}")"'/zbm_set_new_uefi_boot_entries.sh'
 
 declare zpool_name zfs_arch_dataset_name
 zpool_name='zpool'
@@ -674,21 +675,10 @@ function add_zbm_to_efi () {
         local efi_disks_list
         efi_disks_list="$(get_disks_with_one_efipart)"
         if grep -Piq -- '^'"${efi_drive}"'$' <<<"${efi_disks_list}"; then
-            efibootmgr --disk "${efi_drive}" \
-              --part 1 \
-              --create \
-              --label "ZFSBootMenu recovery" \
-              --loader "\EFI\zbm\zfsbootmenu-recovery-vmlinuz-x86_64.EFI" \
-              --verbose
-            efibootmgr --disk "${efi_drive}" \
-              --part 1 \
-              --create \
-              --label "ZFSBootMenu release" \
-              --loader "\EFI\zbm\zfsbootmenu-release-vmlinuz-x86_64.EFI" \
-              --verbose
-        fi
-        efibootmgr
-    fi
+function insert_zbm_postconf_hook () {
+    declare postconf_target_abs='/mnt/etc/zfsbootmenu/posthooks.d/'"$(basename "${postconf_hook}")"
+    curl --silent --location "${postconf_hook}" --output "${postconf_target_abs}"
+    chmod +x "${postconf_target_abs}"
 }
 
 function umount_all () {
@@ -707,7 +697,7 @@ function finalize_os_setup () {
     configure_zfs                               #3.6
     configure_zfs_mount_gen                     #3.7
     configure_zfsbootmenu                       #3.8
-    add_zbm_to_efi                              #3.9
+    insert_zbm_postconf_hook
     umount_all                                  #3.11
 }