login: simply XDG_RUNTIME_DIR management

Lets not pretend we support changing XDG_RUNTIME_DIR via logind state
files. There is no reason to ever write the string into /run, as we
allocate it statically based on the UID, anyway. Lets stop that and just
allocate the runtime_path in "struct User" at all times.

We keep writing it into the /run state to make sure pam_systemd of
previous installs can still read it. However, pam_systemd is now fixed to
allocate it statically as well, so we can safely remove that some time in
the future.

Last but not least: If software depends on systemd, they're more than free
to assume /run/user/$uid is their runtime dir. Lets not require sane
applications to query the environment to get their runtime dir. As long as
applications know their login-UID, they should be safe to deduce the
runtime dir.

1 files changed, 10 insertions, 18 deletions

diff --git a/src/login/pam_systemd.c b/src/login/pam_systemd.c
index 0d61f528db..3f7cbb78df 100644
--- a/src/login/pam_systemd.c
+++ b/src/login/pam_systemd.c
@@ -267,29 +267,21 @@ _public_ PAM_EXTERN int pam_sm_open_session(
 
         pam_get_item(handle, PAM_SERVICE, (const void**) &service);
         if (streq_ptr(service, "systemd-user")) {
-                _cleanup_free_ char *p = NULL, *rt = NULL;
+                _cleanup_free_ char *rt = NULL;
 
-                if (asprintf(&p, "/run/systemd/users/"UID_FMT, pw->pw_uid) < 0)
+                if (asprintf(&rt, "/run/user/"UID_FMT, pw->pw_uid) < 0)
                         return PAM_BUF_ERR;
 
-                r = parse_env_file(p, NEWLINE,
-                                   "RUNTIME", &rt,
-                                   NULL);
-                if (r < 0 && r != -ENOENT)
-                        return PAM_SESSION_ERR;
-
-                if (rt)  {
-                        r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
-                        if (r != PAM_SUCCESS) {
-                                pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
-                                return r;
-                        }
-
-                        r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
-                        if (r != PAM_SUCCESS)
-                                return r;
+                r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
+                if (r != PAM_SUCCESS) {
+                        pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
+                        return r;
                 }
 
+                r = export_legacy_dbus_address(handle, pw->pw_uid, rt);
+                if (r != PAM_SUCCESS)
+                        return r;
+
                 return PAM_SUCCESS;
         }