From 47bb0b8c293f4d730d6739fe8e20039e8887a724 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 25 Apr 2024 12:43:19 +0200
Subject: [PATCH 1/2] errno-util: consider ENOPROTOOPT another "not supported"

It's generated by not supported getsocktopt()/setsockopt() options, and
it's just another way for saying "not supported", hence treat it as
such.
---
 src/basic/errno-util.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/basic/errno-util.h b/src/basic/errno-util.h
index 27804e6382..48b76e4bf7 100644
--- a/src/basic/errno-util.h
+++ b/src/basic/errno-util.h
@@ -167,7 +167,8 @@ static inline bool ERRNO_IS_NEG_NOT_SUPPORTED(intmax_t r) {
                       -EAFNOSUPPORT,
                       -EPFNOSUPPORT,
                       -EPROTONOSUPPORT,
-                      -ESOCKTNOSUPPORT);
+                      -ESOCKTNOSUPPORT,
+                      -ENOPROTOOPT);
 }
 _DEFINE_ABS_WRAPPER(NOT_SUPPORTED);
 

From 78ef66354cd4f24c157f7688e519597a69ceff99 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 25 Apr 2024 12:44:00 +0200
Subject: [PATCH 2/2] varlink: fix varlink_get_peer_pidref() fallback

let's properly handle old kernels that have no pidfd, and use regular
pids in that case, as intended originally.
---
 src/shared/varlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/shared/varlink.c b/src/shared/varlink.c
index f1c00a21b6..d96967b8e6 100644
--- a/src/shared/varlink.c
+++ b/src/shared/varlink.c
@@ -2871,7 +2871,7 @@ int varlink_get_peer_pidref(Varlink *v, PidRef *ret) {
          * authentication. */
 
         r = varlink_acquire_pidfd(v);
-        if (r < 0)
+        if (r < 0 && !ERRNO_IS_NEG_NOT_SUPPORTED(r))
                 return r;
 
         if (v->peer_pidfd < 0) {