systemd: toggle systemd messages when toggling console redirection

Normally systemd is very mute about messages.  It's important,
though for it to be chatty when plymouth is running so we can
show verbose messages to the user when they hit escape.

This commit adds a new --enable-systemd-integration configure
flag which explicitly tells systemd when to print messages to
the console.

This may get dropped in the future in lieu of init script
changes doing this instead of plymouth directly.

2 files changed, 33 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index da9e03db..205607eb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -242,6 +242,13 @@ if test x$enable_upstart_monitoring = xyes; then
 fi
 AM_CONDITIONAL(ENABLE_UPSTART_MONITORING, [test "$enable_upstart_monitoring" = yes])
 
+AC_ARG_ENABLE(systemd-integration, AS_HELP_STRING([--enable-systemd-integration],[coordinate boot up with systemd]),enable_systemd_integration=$enableval,enable_systemd_integration=no)
+AM_CONDITIONAL(ENABLE_SYSTEMD_INTEGRATION, [test "$enable_systemd_integration" = yes])
+
+if text x$enable_systemd_integration = xyes; then
+  AC_DEFINE(PLY_ENABLE_SYSTEMD_INTEGRATION, 1, [Coordinate boot up with systemd])
+fi
+
 AC_ARG_WITH(system-root-install, AS_HELP_STRING([--with-system-root-install],[Install client in /bin and daemon in /sbin]),with_system_root_install=${withval},with_system_root_install=yes)
 AM_CONDITIONAL(WITH_SYSTEM_ROOT_INSTALL,  [test "$with_system_root_install" = yes])
 
diff --git a/src/main.c b/src/main.c
index f6cec9e4..fe87e15a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1501,6 +1501,24 @@ add_displays_and_keyboard_to_boot_splash (state_t           *state,
     }
 }
 
+#ifdef PLY_ENABLE_SYSTEMD_INTEGRATION
+static void
+tell_systemd_to_print_details (state_t *state)
+{
+  ply_trace ("telling systemd to start printing details");
+  if (kill (1, SIGRTMIN + 20) < 0)
+    ply_trace ("could not tell systemd to print details: %m");
+}
+
+static void
+tell_systemd_to_stop_printing_details (state_t *state)
+{
+  ply_trace ("telling systemd to stop printing details");
+  if (kill (1, SIGRTMIN + 21) < 0)
+    ply_trace ("could not tell systemd to stop printing details: %m");
+}
+#endif
+
 static ply_boot_splash_t *
 start_boot_splash (state_t    *state,
                    const char *theme_path,
@@ -1614,6 +1632,10 @@ attach_to_running_session (state_t *state)
   state->is_attached = true;
   state->session = session;
 
+#ifdef PLY_ENABLE_SYSTEMD_INTEGRATION
+  tell_systemd_to_print_details (state);
+#endif
+
   return true;
 }
 
@@ -1626,6 +1648,10 @@ detach_from_running_session (state_t *state)
   if (!state->is_attached)
     return;
 
+#ifdef PLY_ENABLE_SYSTEMD_INTEGRATION
+  tell_systemd_to_stop_printing_details (state);
+#endif
+
   ply_trace ("detaching from terminal session");
   ply_terminal_session_detach (state->session);
   state->is_redirected = false;