1 files changed, 42 insertions, 0 deletions
diff --git a/maildrop/alarm.h b/maildrop/alarm.h
new file mode 100644
index 0000000..01d926c
--- /dev/null
+++ b/maildrop/alarm.h
@@ -0,0 +1,42 @@
+#ifndef	alarm_h
+#define	alarm_h
+
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// This is an asynchronous timer function that is driven by the alarm()
+// system call.  I attempt to implement here a half-baked multiple timer
+// feature.
+//
+// Note - you can't really do a lot in a signal handler, stick to setting
+// global flags, and making system calls ( **NOT** standard library calls).
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#include	"config.h"
+
+class Alarm;
+
+class Alarm {
+
+static Alarm *first, *last;
+
+	Alarm *next, *prev;	// List sorted by expiration interval.
+	unsigned set_interval;	// For how many seconds we're set.
+
+	void	Unlink();
+
+static	void cancel_sig(unsigned);
+static	void set_sig();
+static	RETSIGTYPE alarm_func(int);
+static	unsigned sig_left();
+public:
+	Alarm() : next(0), prev(0), set_interval(0)	{}
+	virtual ~Alarm();
+
+	virtual void handler()=0;
+
+	void	Set(unsigned);
+	void	Cancel();
+} ;
+#endif