ppp: fix config for scarthgap

- use /var/run/ppp/resolv.conf since /etc is not writable.
- use /var/run/lock for lock files, since the directory is not created.

meta-venus/recipes-connectivity/ppp/files/0001-move-resolv.conf-to-var-run-pppd.patch

@@ -0,0 +1,28 @@
+From 193b708083796b7fed96ff624565900b991daaa8 Mon Sep 17 00:00:00 2001
+From: Jeroen Hofstee <jhofstee@victronenergy.com>
+Date: Fri, 21 Feb 2025 11:52:37 +0100
+Subject: [PATCH 1/2] move resolv.conf to /var/run/pppd
+
+/etc/ppp can't be written to in case of a readonly rootfs.
+
+Upstream-Status: Inappropriate [Venus specific]
+---
+ pppd/pathnames.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/pppd/pathnames.h b/pppd/pathnames.h
+index de2fb68..5f9e248 100644
+--- a/pppd/pathnames.h
++++ b/pppd/pathnames.h
+@@ -105,7 +105,7 @@
+ #define PPP_PATH_AUTHDOWN       PPP_PATH_CONFDIR "/auth-down"
+ #define PPP_PATH_TTYOPT         PPP_PATH_CONFDIR "/options."
+ #define PPP_PATH_PEERFILES      PPP_PATH_CONFDIR "/peers/"
+-#define PPP_PATH_RESOLV         PPP_PATH_CONFDIR "/resolv.conf"
++#define PPP_PATH_RESOLV         _PATH_VARRUN "/ppp/resolv.conf"
+
+ #define PPP_PATH_CONNERRS       PPP_PATH_VARLOG  "/connect-errors"
+
+-- 
+2.43.0
+

meta-venus/recipes-connectivity/ppp/files/0002-make-use-of-the-common-lock-dir.patch

@@ -0,0 +1,28 @@
+From cefd8bd3b2dd439c680710af6c75b53554636686 Mon Sep 17 00:00:00 2001
+From: Jeroen Hofstee <jhofstee@victronenergy.com>
+Date: Fri, 21 Feb 2025 11:55:31 +0100
+Subject: [PATCH 2/2] make use of the common lock dir
+
+Since pppd doesn't create the dir hierarchy, writing the lock files fails.
+
+Upstream-Status: Inappropriate [Venus specific]
+---
+ pppd/pathnames.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/pppd/pathnames.h b/pppd/pathnames.h
+index 5f9e248..d39f633 100644
+--- a/pppd/pathnames.h
++++ b/pppd/pathnames.h
+@@ -120,7 +120,7 @@
+ #define PPP_PATH_PPPDB          PPP_PATH_VARRUN  "/pppd2.tdb"
+
+ #ifdef __linux__
+-#define PPP_PATH_LOCKDIR        PPP_PATH_VARRUN  "/lock"
++#define PPP_PATH_LOCKDIR        _PATH_VARRUN  "/lock"
+ #else
+ #ifdef SVR4
+ #define PPP_PATH_LOCKDIR        LOCALSTATEDIR "/spool/locks"
+-- 
+2.43.0
+

meta-venus/recipes-connectivity/ppp/ppp_%.bbappend

@@ -4,6 +4,8 @@ inherit daemontools
 
 SRC_URI += "\
     file://0002-pppd-clear-resolv.conf-on-link-down.patch \
+    file://0001-move-resolv.conf-to-var-run-pppd.patch \
+    file://0002-make-use-of-the-common-lock-dir.patch \
 "
 
 DAEMONTOOLS_RUN = "${sbindir}/pppd call provider nodetach"