session: Optionally do logout/shutdown via dbus commands

configure.ac

@@ -377,8 +377,8 @@ fi
 AM_CONDITIONAL(ENABLE_ZOOM, test "x$enable_zoom" != "xno")
 
 AC_ARG_ENABLE(dbus,
-  AS_HELP_STRING([--enable-dbus], [compile with D-Bus support (experimental) @<:@default=no@:>@]),,
-  enable_dbus=no)
+  AS_HELP_STRING([--enable-dbus], [compile with D-Bus support @<:@default=yes@:>@]),,
+  enable_dbus=yes)
 if test "x$enable_dbus" = "xyes"; then
   PKG_CHECK_MODULES(DBUS, dbus-1, AC_DEFINE(USE_DBUS, 1, [dbus support]), enable_dbus=no)
 fi
@@ -556,6 +556,7 @@ echo "  Render ....................... $enable_xrender"
 echo "  Sync ......................... $enable_xsync"
 echo "  Composite .................... $enable_composite"
 echo "  GNOME session support ........ $with_gnome"
+echo "  D-Bus ........................ $enable_dbus"
 echo "  Window mode helper library ... $enable_libhack"
 echo "  Dialogs ...................... $enable_dialogs"
 echo
@@ -567,7 +568,6 @@ echo
 echo "Experimental options - DO NOT USE unless you know what you are doing"
 echo "  GLX .......................... $enable_glx"
 echo "  ScreenSaver .................. $enable_xscrnsaver"
-echo "  D-Bus ........................ $enable_dbus"
 echo "  XI2 .......................... $enable_xi2"
 echo "  Present....................... $enable_xpresent"
 echo "  Do not use container window .. $enable_containerless"

src/edbus.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007-2021 Kim Woelders
+ * Copyright (C) 2007-2024 Kim Woelders
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
@@ -332,3 +332,93 @@ DbusExit(void)
 {
 }
 #endif
+
+static int
+_DbusSendCommand(DBusBusType bus, const char *dest, const char *path,
+                 const char *meth, const char *args)
+{
+    int             err;
+    DBusError       dberr;
+    DBusConnection *conn;
+    DBusMessage    *msg, *rpl;
+    DBusMessageIter iter;
+    const char     *iface = dest;
+
+    err = -1;
+    msg = rpl = NULL;
+    dbus_error_init(&dberr);
+
+    conn = dbus_bus_get(bus, &dberr);
+    if (dbus_error_is_set(&dberr))
+        goto quit;
+
+    msg = dbus_message_new_method_call(dest, path, iface, meth);
+
+    if (args)
+    {
+        const char     *s = args;
+        int             nr, type, value;
+        dbus_message_iter_init_append(msg, &iter);
+        for (;;)
+        {
+            type = *s++;
+            if (type == '\0')
+                break;
+            if (type == ';')
+                continue;
+            if (*s++ != '=')
+                break;
+            nr = -1;
+            if (type == 'u')
+            {
+                sscanf(s, "%u%n", &value, &nr);
+                if (nr <= 0)
+                    goto quit;
+                s += nr;
+                if (!dbus_message_iter_append_basic(&iter,
+                                                    DBUS_TYPE_UINT32, &value))
+                    goto quit;
+            }
+            else
+            {
+                goto quit;      /* Unknown type */
+            }
+        }
+    }
+
+    rpl = dbus_connection_send_with_reply_and_block(conn, msg, 100, &dberr);
+    if (!rpl)
+        goto quit;
+
+    dbus_connection_flush(conn);
+
+    err = 0;
+
+  quit:
+    if (dbus_error_is_set(&dberr))
+    {
+        Eprintf("*** Dbus error: %s\n", dberr.message);
+        dbus_error_free(&dberr);
+    }
+
+    if (msg)
+        dbus_message_unref(msg);
+    if (rpl)
+        dbus_message_unref(rpl);
+
+    return err;
+}
+
+int
+DbusRequestLogout(void)
+{
+    return _DbusSendCommand(DBUS_BUS_SESSION, "org.gnome.SessionManager",
+                            "/org/gnome/SessionManager", "Logout", "u=0");
+}
+
+int
+DbusRequestShutdown(void)
+{
+    return _DbusSendCommand(DBUS_BUS_SESSION, "org.gnome.SessionManager",
+                            "/org/gnome/SessionManager", "Shutdown", NULL);
+}

src/edbus.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 Kim Woelders
+ * Copyright (C) 2007-2024 Kim Woelders
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
@@ -26,4 +26,7 @@
 void            DbusInit(void);
 void            DbusExit(void);
 
+int             DbusRequestLogout(void);
+int             DbusRequestShutdown(void);
+
 #endif                          /* _EDBUS_H_ */

src/session.c

@@ -31,6 +31,9 @@
 #include "snaps.h"
 #include "user.h"
 #include "xwin.h"
+#if USE_DBUS
+#include "edbus.h"
+#endif
 
 #ifdef USE_EXT_INIT_WIN
 static EX_Window new_init_win_ext = NoXID;
@@ -533,6 +536,31 @@ doSMExit(int mode, const char *params)
 #define LOGOUT_SUSPEND      5
 #define LOGOUT_HIBERNATE    6
 
+#if USE_DBUS
+static int
+_SessionExitDbus(int how)
+{
+    if (Mode.wm.window)
+        return -1;
+
+    switch (how)
+    {
+    default:
+    case LOGOUT_LOCK:
+    case LOGOUT_SUSPEND:
+    case LOGOUT_HIBERNATE:
+        return -1;
+
+    case LOGOUT_EXIT:
+        return DbusRequestLogout();
+
+    case LOGOUT_REBOOT:
+    case LOGOUT_HALT:
+        return DbusRequestShutdown();
+    }
+}
+#endif                          /* USE_DBUS */
+
 static void
 _SessionLogout(int how)
 {
@@ -552,6 +580,11 @@ _SessionLogout(int how)
 
 #endif                          /* USE_SM */
 
+#if USE_DBUS
+    if (_SessionExitDbus(how) == 0)
+        return;
+#endif
+
     switch (how)
     {
     default: