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-rw-r--r--libc/inet/if_nametoindex.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/libc/inet/if_nametoindex.c b/libc/inet/if_nametoindex.c
index a697419b6..45b319f97 100644
--- a/libc/inet/if_nametoindex.c
+++ b/libc/inet/if_nametoindex.c
@@ -148,6 +148,27 @@ struct if_nameindex * if_nameindex (void)
char * if_indextoname (unsigned int ifindex, char *ifname)
{
+#ifdef SIOCGIFNAME
+ /* Use ioctl to avoid searching the list. */
+ struct ifreq ifr;
+ int fd, saved_errno;
+
+ fd = __opensock ();
+
+ if (fd < 0)
+ return NULL;
+
+ ifr.ifr_ifindex = ifindex;
+ if (ioctl (fd, SIOCGIFNAME, &ifr) < 0) {
+ saved_errno = errno;
+ close (fd);
+ __set_errno (saved_errno);
+ return NULL;
+ }
+ close (fd);
+
+ return strncpy (ifname, ifr.ifr_name, IFNAMSIZ);
+#else
struct if_nameindex *idx;
struct if_nameindex *p;
char *result = NULL;
@@ -163,5 +184,6 @@ char * if_indextoname (unsigned int ifindex, char *ifname)
if_freenameindex (idx);
}
return result;
+#endif
}