logind: log wall messages to the journal

Currently kde installs a fake utmp session to listen for this. This provides an
alternative mechanism as discussed in #23574.

Example with 'shutdown 6 -r' and shutdown -c':
    PRIORITY=6
    SYSLOG_FACILITY=4
    SYSLOG_IDENTIFIER=systemd-logind
    ...
    CODE_FILE=src/login/logind-utmp.c
    CODE_LINE=90
    CODE_FUNC=warn_wall
    MESSAGE_ID=9e7066279dc8403da79ce4b1a69064b2
    OPERATOR=root
    MESSAGE=The system will reboot at Thu 2022-06-30 12:16:43 CEST!
    ACTION=reboot

    PRIORITY=5
    SYSLOG_FACILITY=4
    SYSLOG_IDENTIFIER=systemd-logind
    ...
    OPERATOR=root
    CODE_FILE=src/login/logind-dbus.c
    CODE_LINE=2407
    CODE_FUNC=method_cancel_scheduled_shutdown
    MESSAGE=System shutdown has been cancelled
    MESSAGE_ID=249f6fb9e6e2428c96f3f0875681ffa3
    ACTION=reboot

1 files changed, 19 insertions, 12 deletions

diff --git a/src/login/logind-utmp.c b/src/login/logind-utmp.c
index ccf959cd73..06b1bcf9b4 100644
--- a/src/login/logind-utmp.c
+++ b/src/login/logind-utmp.c
@@ -64,30 +64,37 @@ bool logind_wall_tty_filter(const char *tty, bool is_local, void *userdata) {
 }
 
 static int warn_wall(Manager *m, usec_t n) {
-        int r;
-
         assert(m);
 
-        if (!m->enable_wall_messages || !m->scheduled_shutdown_action)
+        if (!m->scheduled_shutdown_action)
                 return 0;
 
-        usec_t left = m->scheduled_shutdown_timeout > n;
+        bool left = m->scheduled_shutdown_timeout > n;
 
-        _cleanup_free_ char *l = NULL, *username = NULL;
-
-        r = asprintf(&l, "%s%sThe system will %s %s%s!",
+        _cleanup_free_ char *l = NULL;
+        if (asprintf(&l, "%s%sThe system will %s %s%s!",
                      strempty(m->wall_message),
                      isempty(m->wall_message) ? "" : "\n",
                      handle_action_verb_to_string(m->scheduled_shutdown_action->handle),
                      left ? "at " : "now",
-                     left ? FORMAT_TIMESTAMP(m->scheduled_shutdown_timeout) : "");
-        if (r < 0) {
+                     left ? FORMAT_TIMESTAMP(m->scheduled_shutdown_timeout) : "") < 0) {
+
                 log_oom();
-                return 0;
+                return 1;  /* We're out-of-memory for now, but let's try to print the message later */
         }
 
-        username = uid_to_name(m->scheduled_shutdown_uid);
-        utmp_wall(l, username, m->scheduled_shutdown_tty, logind_wall_tty_filter, m);
+        _cleanup_free_ char *username = uid_to_name(m->scheduled_shutdown_uid);
+
+        int level = left ? LOG_INFO : LOG_NOTICE;
+
+        log_struct(level,
+                   LOG_MESSAGE("%s", l),
+                   "ACTION=%s", handle_action_to_string(m->scheduled_shutdown_action->handle),
+                   "MESSAGE_ID=" SD_MESSAGE_LOGIND_SHUTDOWN_STR,
+                   username ? "OPERATOR=%s" : NULL, username);
+
+        if (m->enable_wall_messages)
+                utmp_wall(l, username, m->scheduled_shutdown_tty, logind_wall_tty_filter, m);
 
         return 1;
 }