Merge pull request #32474 from poettering/varlink-no-pidfd

varlink: tweak fallback for SO_PEERPIDFD on old kernels

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);
 

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) {