Add unix signal integration with the iomux

include/ucore/iomux_signal.h

@@ -0,0 +1,48 @@
+#ifndef UC_IOMUX_SIGNAL_H_
+#define UC_IOMUX_SIGNAL_H_
+
+#include "ucore/iomux.h"
+/** Callback signature for handling unix signals.
+ * @param mux associated mux
+ * @param signo unix signal number
+ * @param cookie value passed to iomux_register_unixsignal
+ */
+typedef void (*IOMuxSignalHandler)(struct IOMux *mux, int signo, void *cookie);
+
+
+/** Register a handler for a unix signal.
+ * The handler is invoked as normally within the iomux loop.
+ * Note, only one handler per signal can be used.
+ * 
+ * The current implementation has the limitation that only 
+ * one IOMux can globally be registered to handle signals.
+ * All signals must be unregistered prior to deleting the
+ * IOMux that is set up to handle signals.
+ * 
+ * @param mux associated IOMux
+ * @param signo the signal (see man signal) to handle
+ * @param handler callback that will be called whrn the signal is caught
+ * @param cookie value passed back to the handler
+ *
+ * @return 0 on success, errno if registring the signal failed.
+ *         (EINVAL if another mux is registered for signals,
+ *          EEXISTS if a signal handler is already registered for the signo
+ *          ENOMEM if memory allocation failed
+ *          other errno values from syscalls)
+ *
+ */
+int iomux_register_unixsignal(struct IOMux *mux, 
+                      int signo, 
+                      IOMuxSignalHandler handler, 
+                      void *cookie);
+
+/** Unregister the current handler for a signal.
+ *
+ * @param mux associated mux
+ * @param signo signal number handler to unregister
+ * @return 0 on success, errno value on failure (ENOENT if
+ *         no signal handler was registered for signo)
+ */
+int iomux_unregister_unixsignal(struct IOMux *mux, int signo);
+
+#endif