core/namespace: add comment to explain the non-obvious assumption on /run/systemd...

Follow-up for 119820f8abf587f96a11fb1f28ef854e84bc3122

Addresses https://github.com/systemd/systemd/pull/32487#discussion_r1743493196

diff --git a/src/core/namespace.c b/src/core/namespace.c
index 026018438c8d5070377b2482ac4137dd16fb4b0d..a38bad147421f9b295a8f573c01fa2ad568212b8 100644 (file)
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -1148,6 +1148,8 @@ static int mount_private_dev(const MountEntry *m, const NamespaceParameters *p)
         FOREACH_STRING(d, "/dev/mqueue", "/dev/hugepages")
                 (void) bind_mount_device_dir(temporary_mount, d);
 
+        /* We assume /run/systemd/journal/ is available if not changing root, which isn't entirely accurate
+         * but shouldn't matter, as either way the user would get ENOENT when accessing /dev/log */
         if ((!p->root_image && !p->root_directory) || p->bind_journal_sockets) {
                 const char *devlog = strjoina(temporary_mount, "/dev/log");
                 if (symlink("/run/systemd/journal/dev-log", devlog) < 0)