source: scripts/fetch/eglibc/2.10.1/35-dynamic_resolv.patch@ d38577a

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

http://bugs.gentoo.org/177416

--- libc/resolv/res_libc.c
+++ libc/resolv/res_libc.c
@@ -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
@@ -101,6 +102,20 @@
 __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_nclose (resp);