From 55c9b54b13305683e67300f2e172a9453f5b0526 Mon Sep 17 00:00:00 2001
From: Stefan Agner <stefan@agner.ch>
Date: Mon, 27 Dec 2021 14:58:19 +0100
Subject: [PATCH] Check if Busybox supports oflag (#1692) (#1694)

* Check if Busybox supports oflag

It seems that Busybox' dd shipped with OS release 5 and earlier does not
support oflag. Check if the flag is supported before making use of it.

* Exit if a command in the update scripts returns an error

This makes sure that the update isn't marked as successful in case there
is an error in the update script.
---
 buildroot-external/ota/rauc-hook | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/buildroot-external/ota/rauc-hook b/buildroot-external/ota/rauc-hook
index 92410492c..549211fdf 100755
--- a/buildroot-external/ota/rauc-hook
+++ b/buildroot-external/ota/rauc-hook
@@ -1,5 +1,7 @@
 #!/bin/sh
 
+set -o errexit
+
 ##
 # Hooks
 
@@ -65,12 +67,17 @@ if [ "${RAUC_SLOT_CLASS}" = "spl" ]; then
     DEVICE_ROOT="/dev/$(lsblk -no pkname "${DEVICE_CHILD}")"
     PART_TABLE="$(sfdisk -lqJ "${DEVICE_ROOT}")"
     PART_LABEL="$(echo "${PART_TABLE}" | jq -r '.partitiontable.label')"
+    FLAGS=""
+
+    if dd oflag=direct if=/dev/null 2> /dev/null; then
+        FLAGS="oflag=direct"
+    fi
 
     if [ "${PART_LABEL}" = "gpt" ]; then
-        dd if="${RAUC_IMAGE_NAME}" of="${DEVICE_ROOT}" conv=notrunc oflag=direct bs=512 seek=2 skip=2
+        dd if="${RAUC_IMAGE_NAME}" of="${DEVICE_ROOT}" conv=notrunc ${FLAGS} bs=512 seek=2 skip=2
     else
-        dd if="${RAUC_IMAGE_NAME}" of="${DEVICE_ROOT}" conv=notrunc oflag=direct bs=1 count=440
-        dd if="${RAUC_IMAGE_NAME}" of="${DEVICE_ROOT}" conv=notrunc oflag=direct bs=512 seek=1 skip=1
+        dd if="${RAUC_IMAGE_NAME}" of="${DEVICE_ROOT}" conv=notrunc ${FLAGS} bs=1 count=440
+        dd if="${RAUC_IMAGE_NAME}" of="${DEVICE_ROOT}" conv=notrunc ${FLAGS} bs=512 seek=1 skip=1
     fi
 fi