ifupdown: do not fail if interface disappears during ifdown

Interface may not exist because it got deleted by an ifdown hook script
earlier. This may happen when a virtual interface, such as VLAN, has multiple
iface blocks defined.

function                                             old     new   delta
static_down6                                          14      40     +26
static_down                                           54      70     +16
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 42/0)               Total: 42 bytes

Signed-off-by: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 534c9f0c7..5481134e5 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -138,6 +138,7 @@
 //usage:     "\n        -v      Print out what would happen before doing it"
 //usage:     "\n        -f      Force deconfiguration"
 
+#include <net/if.h>
 #include "libbb.h"
 #include "common_bufsiz.h"
 /* After libbb.h, since it needs sys/types.h on some systems */
@@ -503,6 +504,8 @@ static int FAST_FUNC static_up6(struct interface_defn_t *ifd, execfn *exec)
 
 static int FAST_FUNC static_down6(struct interface_defn_t *ifd, execfn *exec)
 {
+        if (!if_nametoindex(ifd->iface))
+                return 1; /* already gone */
 # if ENABLE_FEATURE_IFUPDOWN_IP
         return execute("ip link set %iface% down", ifd, exec);
 # else
@@ -598,6 +601,9 @@ static int FAST_FUNC static_up(struct interface_defn_t *ifd, execfn *exec)
 static int FAST_FUNC static_down(struct interface_defn_t *ifd, execfn *exec)
 {
         int result;
+
+        if (!if_nametoindex(ifd->iface))
+                return 2; /* already gone */
 # if ENABLE_FEATURE_IFUPDOWN_IP
         /* Optional "label LBL" is necessary if interface is an alias (eth0:0),
          * otherwise "ip addr flush dev eth0:0" flushes all addresses on eth0.