ifupdown: support post-up / pre-down hooks

function                                             old     new   delta
set_environ                                          330     371     +41
ifupdown_main                                       2156    2194     +38
iface_up                                              97     113     +16
iface_down                                            97     113     +16
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 111/0)             Total: 111 bytes

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 3820330..abc6b58 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -891,6 +891,8 @@
 				if (strcmp(first_word, "up") != 0
 				 && strcmp(first_word, "down") != 0
 				 && strcmp(first_word, "pre-up") != 0
+				 && strcmp(first_word, "pre-down") != 0
+				 && strcmp(first_word, "post-up") != 0
 				 && strcmp(first_word, "post-down") != 0
 				) {
 					int i;
@@ -987,6 +989,8 @@
 		if (strcmp(iface->option[i].name, "up") == 0
 		 || strcmp(iface->option[i].name, "down") == 0
 		 || strcmp(iface->option[i].name, "pre-up") == 0
+		 || strcmp(iface->option[i].name, "pre-down") == 0
+		 || strcmp(iface->option[i].name, "post-up") == 0
 		 || strcmp(iface->option[i].name, "post-down") == 0
 		) {
 			continue;
@@ -1056,6 +1060,7 @@
 	if (!execute_all(iface, "pre-up")) return 0;
 	if (!iface->method->up(iface, doit)) return 0;
 	if (!execute_all(iface, "up")) return 0;
+	if (!execute_all(iface, "post-up")) return 0;
 	return 1;
 }
 
@@ -1063,6 +1068,7 @@
 {
 	if (!iface->method->down(iface,check)) return -1;
 	set_environ(iface, "stop");
+	if (!execute_all(iface, "pre-down")) return 0;
 	if (!execute_all(iface, "down")) return 0;
 	if (!iface->method->down(iface, doit)) return 0;
 	if (!execute_all(iface, "post-down")) return 0;