tap: Explicitly cast TUNSETIFF to fix build warning with musl on ppc64le

On ppc64le, TUNSETIFF happens to be 2147767498, which is bigger than
INT_MAX (2^31 - 1), and musl declares the second argument of ioctl()
as 'int', not 'unsigned long' like glibc does, probably because of how
POSIX specifies the equivalent argument, int dcmd, in posix_devctl(),
so gcc reports a warning:

tap.c: In function 'tap_ns_tun':
tap.c:1291:24: warning: overflow in conversion from 'long unsigned int' to 'int' changes value from '2147767498' to '-2147199798' [-Woverflow]
 1291 |         rc = ioctl(fd, TUNSETIFF, &ifr);
      |                        ^~~~~~~~~

We don't care about that overflow, so explicitly cast TUNSETIFF to
int.

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

1 files changed, 1 insertions, 1 deletions

diff --git a/tap.c b/tap.c
index cfb82e9..f638f2c 100644
--- a/tap.c
+++ b/tap.c
@@ -1288,7 +1288,7 @@ static int tap_ns_tun(void *arg)
 	if (fd < 0)
 		die_perror("Failed to open() /dev/net/tun");
 
-	rc = ioctl(fd, TUNSETIFF, &ifr);
+	rc = ioctl(fd, (int)TUNSETIFF, &ifr);
 	if (rc < 0)
 		die_perror("TUNSETIFF ioctl on /dev/net/tun failed");