cgroup-util: explain why cg_pidref_get_path() cannot be ported over to pidfd helpers...

See also: https://github.com/systemd/systemd/pull/35242#issuecomment-2506686806

diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index 50f1f0e4df2c3e809e8e464962535354ec2c6980..1d2faa7393f5a7de2ab4bfa56e2d335d41d314a8 100644 (file)
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -861,6 +861,10 @@ int cg_pidref_get_path(const char *controller, const PidRef *pidref, char **ret_
         if (!pidref_is_set(pidref))
                 return -ESRCH;
 
+        // XXX: Ideally we'd use pidfd_get_cgroupid() + cg_path_from_cgroupid() here, to extract this
+        // bit of information from pidfd directly. However, the latter requires privilege and it's
+        // not entirely clear how to handle cgroups from outer namespace.
+
         r = cg_pid_get_path(controller, pidref->pid, &path);
         if (r < 0)
                 return r;