signal: reserve signal subsystems >= INT_MAX/2 for libraries

The first range (from 0 to INT_MAX/2) of signal subsystems can be
used by client applications while the second range (from INT_MAX)
is reserved for libraries.

This is useful to support signals defined in libraries that
may be used by different client applications.

diff --git a/include/osmocom/core/signal.h b/include/osmocom/core/signal.h
index 535fd18..7c32c77 100644 (file)
--- a/include/osmocom/core/signal.h
+++ b/include/osmocom/core/signal.h
@@ -1,6 +1,29 @@
 #ifndef OSMO_SIGNAL_H
 #define OSMO_SIGNAL_H
 
+#include <stdint.h>
+
+/* subsystem signaling numbers: we split the numberspace for applications and
+ * libraries: from 0 to UINT_MAX/2 for applications, from UINT_MAX/2 to
+ * UINT_MAX for libraries. */
+#define OSMO_SIGNAL_SS_APPS            0
+#define OSMO_SIGNAL_SS_RESERVED                2147483648
+
+/* signal subsystems. */
+enum {
+       SS_GLOBAL               = OSMO_SIGNAL_SS_RESERVED,
+       SS_INPUT,
+};
+
+/* application-defined signal types. */
+#define OSMO_SIGNAL_T_APPS             0
+#define OSMO_SIGNAL_T_RESERVED         2147483648
+
+/* signal types. */
+enum {
+       S_GLOBAL_SHUTDOWN       = OSMO_SIGNAL_T_RESERVED,
+};
+
 typedef int osmo_signal_cbfn(unsigned int subsys, unsigned int signal, void *handler_data, void *signal_data);