auto-provisioning: improve behavior with power cuts

Some users when auto-provisioning, power down the system once they see
the auto-provisioning service exit successfully. However, in some cases
this can cause the files created from the provisioning process to not be
fully written to disk, resulting in 0-byte files upon next boot.

Therefore, add an explicit sync after the files are written to improve
the behavior of the auto-provisioning in these cases.

Related-to: TOR-3743

Signed-off-by: Jeremias Cordoba <[email protected]>

recipes-sota/auto-provisioning/auto-provisioning/auto-provisioning.sh

@@ -136,16 +136,33 @@ register_device() {
 }
 
 write_credentials() {
+    local temp_dir src_hash hash
+
     log "Updating device credentials"
 
-    rm -Rf $SOTA_CRED_DIR && mkdir -p $SOTA_CRED_DIR
-    if ! unzip device.zip -d $SOTA_CRED_DIR >/dev/null; then
+    temp_dir="${SOTA_CRED_DIR}.tmp"
+    rm -Rf ${temp_dir} && mkdir -p ${temp_dir}
+    if ! unzip device.zip -d ${temp_dir} >/dev/null; then
         exit_error "Failed extracting credentials file"
     fi
+    sync
+
+    # Double-check hashes for extra validation
+    for file in $(unzip -l device.zip | awk '/-----/ {p = ++p % 2; next} p {print $NF}'); do
+        src_hash=$(unzip -p device.zip ${file} | sha256sum | cut -d ' ' -f1)
+	actual_hash=$(sha256sum ${temp_dir}/${file} | cut -d ' ' -f1)
+	if [ "$src_hash" != "$actual_hash" ]; then
+	    rm -rf ${temp_dir}
+            exit_error "Hash mismatch on file $file"
+        fi
+    done
 
-    rm -rf $SOTA_BASE_DIR/sql.db
+    rm -rf ${SOTA_CRED_DIR}
+    mv -f ${temp_dir} ${SOTA_CRED_DIR}
 
-    rm -rf $CONFIG_FILE
+    rm -rf ${SOTA_BASE_DIR}/sql.db
+    rm -rf ${CONFIG_FILE}
+    sync
 }
 
 restart_services() {