Original patch from: gentoo/src/patchsets/glibc/2.9/1055_all_glibc-resolv-dynamic.patch

-= BEGIN original header =-
ripped from SuSE

if /etc/resolv.conf is updated, then make sure applications
already running get the updated information.

http://bugs.gentoo.org/177416

-= END original header =-

diff -durN glibc-2_9.orig/resolv/res_libc.c glibc-2_9/resolv/res_libc.c
--- glibc-2_9.orig/resolv/res_libc.c	2006-10-11 10:59:28.000000000 +0200
+++ glibc-2_9/resolv/res_libc.c	2009-02-02 22:00:57.000000000 +0100
@@ -22,6 +22,7 @@
 #include <arpa/nameser.h>
 #include <resolv.h>
 #include <bits/libc-lock.h>
+#include <sys/stat.h>
 
 
 /* The following bit is copied from res_data.c (where it is #ifdef'ed
@@ -95,6 +96,20 @@
 __res_maybe_init (res_state resp, int preinit)
 {
 	if (resp->options & RES_INIT) {
+		static time_t last_mtime, last_check;
+		time_t now;
+		struct stat statbuf;
+		
+		time (&now);
+		if (now != last_check) {
+			last_check = now;
+			if (stat (_PATH_RESCONF, &statbuf) == 0 && last_mtime != statbuf.st_mtime) {
+				last_mtime = statbuf.st_mtime;
+				atomicinclock (lock);
+				atomicinc (__res_initstamp);
+				atomicincunlock (lock);
+			}
+		}
 		if (__res_initstamp != resp->_u._ext.initstamp) {
 			if (resp->nscount > 0) {
 				__res_iclose (resp, true);