Init scripts: generalize config file setup

board/common/overlay/etc/init.d/base

@@ -8,6 +8,7 @@ test -n "$os_debug" || source /etc/init.d/conf
 
 source /etc/init.d/panic
 
+
 msg_begin() {
     echo -n " * $1: "
 }
@@ -24,3 +25,35 @@ msg_background() {
     test -n "$1" && echo $1 || echo "pending"
 }
 
+prepare_conf() {
+    # $1 - actual config file
+    # $2 - system-provided config file
+    # $3 - user-provided config file
+    
+    # long story short:
+    #  * user conf file takes precedence, if present
+    #  * system conf file is used by default, if actual file absent
+    
+    actual_conf="$1"
+    system_conf="$2"
+    user_conf="$3"
+    
+    if [[ -n "$user_conf" && -f "$user_conf" ]]; then
+        cp -f "$user_conf" "$actual_conf"
+        grep -E "/boot .*ro[\s,]" /proc/mounts
+        RO=$?
+        test $RO == 0 && mount -o remount,rw /boot
+        rm -f $user_conf
+        test $RO == 0 && mount -o remount,ro /boot
+    fi
+
+    if [[ ! -f "$actual_conf" && -f "$system_conf" ]]; then
+        cp "$system_conf" "$actual_conf"
+    fi
+
+    # we want only Unix newlines in conf files
+    if [[ -f "$actual_conf" ]]; then
+        sed -i 's/\r//g' "$actual_conf"
+    fi
+}
+