Add lextra.c and extra library, with sleep() now part of it instead of in os

lextra.c

@@ -0,0 +1,68 @@
+/***
+ * Extra functions that don't
+ * fit into any other category.
+ *
+ * This module does not provide its
+ * own table; all functions here are
+ * found in the global table.
+ *
+ * @module extra
+ */
+
+#include <time.h>
+
+#include <lua.h>
+#include <lauxlib.h>
+
+#include "lcallisto.h"
+#include "util.h"
+
+
+/***
+ * Waits the specified amount of seconds.
+ *
+ * @function sleep
+ * @usage
+local minutes = 5
+sleep(minutes * 60) -- 5 minutes
+ * @tparam number seconds The amount of seconds to wait.
+ */
+static int
+extra_sleep(lua_State *L)
+{
+	/* Implementation from luasocket */
+	double n;
+	struct timespec t, r;
+
+	n = luaL_checknumber(L, 1);
+
+	if (n < 0.0)
+		n = 0.0;
+	if (n > INT_MAX)
+		n = INT_MAX;
+
+	t.tv_sec = (int)n;
+	n -= t.tv_sec;
+	t.tv_nsec = (int)(n * 1000000000);
+
+	if (t.tv_nsec >= 1000000000)
+		t.tv_nsec = 999999999;
+
+	while (nanosleep(&t, &r) != 0) {
+		t.tv_sec = r.tv_sec;
+		t.tv_nsec = r.tv_nsec;
+	}
+	return 0;
+}
+
+static const luaL_Reg extlib[] = {
+	{"sleep", extra_sleep},
+	{NULL, NULL}
+};
+
+int
+callistoopen_extra(lua_State *L)
+{
+	newoverride(L, extlib, CALLISTO_EXTLIBNAME);
+	return 1;
+}