add a note that SO_BINDTODEVICE needs padded iface name on 2.6.26

diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index d078e98111545a9887cc834f9f30a13e7c40e5f8..2eb4cb9be2aaf1a6ea8aadabb57d02619edc0340 100644 (file)
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -24,7 +24,9 @@ int FAST_FUNC setsockopt_bindtodevice(int fd, const char *iface)
        int r;
        struct ifreq ifr;
        strncpy_IFNAMSIZ(ifr.ifr_name, iface);
-       /* Actually, ifr_name is at offset 0, and in practice
+       /* NB: passing (iface, strlen(iface) + 1) does not work!
+        * (maybe it works on _some_ kernels, but not on 2.6.26)
+        * Actually, ifr_name is at offset 0, and in practice
         * just giving char[IFNAMSIZ] instead of struct ifreq works too.
         * But just in case it's not true on some obscure arch... */
        r = setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr));