reload /etc/resolv.conf when it has changed

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

ripped from SuSE

http://bugs.gentoo.org/177416

diff --git a/resolv/res_libc.c b/resolv/res_libc.c
index a4b376f15b0b0e9830cc08b8212a71da4bb10684..848f773958771703a508b6c36e938478f92f9a55 100644 (file)
--- a/resolv/res_libc.c
+++ b/resolv/res_libc.c
@@ -25,6 +25,7 @@
 #include <arpa/nameser.h>
 #include <resolv.h>
 #include <libc-lock.h>
+#include <sys/stat.h>
 
 extern unsigned long long int __res_initstamp attribute_hidden;
 /* We have atomic increment operations on 64-bit platforms.  */
@@ -93,6 +94,20 @@ int
 __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);