core: use g_unix_signal_add() for more reliable Unix signal handling

There were a few problems with MM's existing signal handling, first
of which was that calling g_main_loop_quit() from a signal handler
only works 50% of the time due to severe restrictions on what you
can do from the handler. This caused INT or TERM to sometimes be
ignored by MM.

Instead, use the glib signal functions which ensure that the handler
is run in the right context, where we can do anything we want.

3 files changed, 29 insertions, 17 deletions

diff --git a/src/main.c b/src/main.c
index 0f8119ee..584ece82 100644
--- a/src/main.c
+++ b/src/main.c
@@ -32,18 +32,37 @@
 
 static GMainLoop *loop = NULL;
 
+#if GLIB_CHECK_VERSION(2,30,0)
+#include <glib-unix.h>
+
+static gboolean
+quit_cb (gpointer user_data)
+{
+	mm_info ("Caught signal, shutting down...");
+    if (loop)
+        g_idle_add ((GSourceFunc) g_main_loop_quit, loop);
+    else
+        _exit (0);
+    return FALSE;
+}
+
+static void
+setup_signals (void)
+{
+    g_unix_signal_add (SIGTERM, quit_cb, NULL);
+    g_unix_signal_add (SIGINT, quit_cb, NULL);
+}
+
+#else
+
 static void
 mm_signal_handler (int signo)
 {
-    if (signo == SIGUSR1)
-        mm_log_usr1 ();
-	else if (signo == SIGINT || signo == SIGTERM) {
-		mm_info ("Caught signal %d, shutting down...", signo);
-        if (loop)
-            g_main_loop_quit (loop);
-        else
-            _exit (0);
-    }
+	mm_info ("Caught signal %d, shutting down...", signo);
+    if (loop)
+        g_main_loop_quit (loop);
+    else
+        _exit (0);
 }
 
 static void
@@ -56,10 +75,10 @@ setup_signals (void)
     action.sa_handler = mm_signal_handler;
     action.sa_mask = mask;
     action.sa_flags = 0;
-    sigaction (SIGUSR1, &action, NULL);
     sigaction (SIGTERM, &action, NULL);
     sigaction (SIGINT, &action, NULL);
 }
+#endif
 
 static void
 destroy_cb (DBusGProxy *proxy, gpointer user_data)
diff --git a/src/mm-log.c b/src/mm-log.c
index f99f51f5..5e02ff9b 100644
--- a/src/mm-log.c
+++ b/src/mm-log.c
@@ -221,11 +221,6 @@ mm_log_setup (const char *level,
 }
 
 void
-mm_log_usr1 (void)
-{
-}
-
-void
 mm_log_shutdown (void)
 {
     if (logfd < 0)
diff --git a/src/mm-log.h b/src/mm-log.h
index 6024c08f..729cf226 100644
--- a/src/mm-log.h
+++ b/src/mm-log.h
@@ -55,8 +55,6 @@ gboolean mm_log_setup (const char *level,
                        gboolean rel_ts,
                        GError **error);
 
-void mm_log_usr1 (void);
-
 void mm_log_shutdown (void);
 
 #endif  /* MM_LOG_H */