Dynamically manage service states based on user defined conditions

Old event system has been replaced with a more generic condition
concept. The idea is that finit plugins may provide arbitrary
conditions that services may specify as dependencies that they require
to run.

In order to accomodate this, the service management has been
redesigned to use a state machine.

plugins/netlink.c

@@ -16,6 +16,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <arpa/inet.h>
 #include <errno.h>
 #include <net/if.h>		/* IFNAMSIZ */
 #include <sys/socket.h>
@@ -25,7 +26,7 @@
 #include <unistd.h>
 
 #include "../finit.h"
-#include "../event.h"
+#include "../cond.h"
 #include "../helpers.h"
 #include "../plugin.h"
 
@@ -86,13 +87,10 @@ static void nl_route(struct nlmsghdr *nlmsg)
 	}
 
 	if ((!dst && !mask) && (gw || idx)) {
-		char msg[MAX_ARG_LEN];
-
 		if (nlmsg->nlmsg_type == RTM_DELROUTE)
-			snprintf(msg, sizeof(msg), "GW:DN");
+			cond_clear("net/gw");
 		else
-			snprintf(msg, sizeof(msg), "GW:UP");
-		event_dispatch(msg);
+			cond_set("net/gw");
 	}
 }
 
@@ -123,19 +121,24 @@ static void nl_link(struct nlmsghdr *nlmsg)
 				 * New interface has appearad, or interface flags has changed.
 				 * Check ifi_flags here to see if the interface is UP/DOWN
 				 */
-				if (i->ifi_change & IFF_UP)
-					snprintf(msg, sizeof(msg), "IF%s:%s",
-						 (i->ifi_flags & IFF_UP) ? "UP" : "DN",
-						 ifname);
-				else
-					snprintf(msg, sizeof(msg), "IFADD:%s", ifname);
-				event_dispatch(msg);
+				if (i->ifi_change & IFF_UP) {
+					snprintf(msg, sizeof(msg), "net/%s/up", ifname);
+
+					if (i->ifi_flags & IFF_UP)
+						cond_set(msg);
+					else
+						cond_clear(msg);
+
+				} else {
+					snprintf(msg, sizeof(msg), "net/%s/exist", ifname);
+					cond_set(msg);
+				}
 				break;
 
 			case RTM_DELLINK:
 				/* NOTE: Interface has dissapeared, not link down ... */
-				snprintf(msg, sizeof(msg), "IFDEL:%s", ifname);
-				event_dispatch(msg);
+				snprintf(msg, sizeof(msg), "net/%s/exist", ifname);
+				cond_clear(msg);
 				break;
 
 			case RTM_NEWADDR: