util: Make ns_enter() a void function and report setns() errors

ns_enter() returns an integer... but it's always zero.  If we actually fail
the function doesn't return.  Therefore it makes more sense for this to be
a function returning void, and we can remove the cases where we pointlessly
checked its return value.

In addition ns_enter() is usually called from an ephemeral thread created
by NS_CALL().  That means that the exit(EXIT_FAILURE) there usually won't
be reported (since NS_CALL() doesn't wait() for the thread).  So, use die()
instead to print out some information in the unlikely event that our
setns() here does fail.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/tap.c b/tap.c
index a6a73d3..0f90cab 100644
--- a/tap.c
+++ b/tap.c
@@ -1182,9 +1182,9 @@ static int tap_ns_tun(void *arg)
 	struct ctx *c = (struct ctx *)arg;
 
 	memcpy(ifr.ifr_name, c->pasta_ifn, IFNAMSIZ);
+	ns_enter(c);
 
-	if (ns_enter(c) ||
-	    (tun_ns_fd = open("/dev/net/tun", flags)) < 0 ||
+	if ((tun_ns_fd = open("/dev/net/tun", flags)) < 0 ||
 	    ioctl(tun_ns_fd, TUNSETIFF, &ifr) ||
 	    !(c->pasta_ifi = if_nametoindex(c->pasta_ifn))) {
 		if (tun_ns_fd != -1)