libc: Note resolv_conf=/dev/null will avoid overwriting resolv.conf

Author: rsmarples

libc.in

@@ -94,6 +94,9 @@ elif [ -d "$SYSCONFDIR"/resolvconf ]; then
 	fi
 fi
 : ${resolv_conf:=/etc/resolv.conf}
+if [ "$resolv_conf" = "/dev/null" ]; then
+	exit 0
+fi
 : ${resolv_conf_tmp:="$resolv_conf.$$.openresolv"}
 : ${libc_service:=nscd}
 : ${list_resolv:=@SBINDIR@/resolvconf -L}

resolvconf.conf.5.in

@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 24, 2025
+.Dd April 21, 2025
 .Dt RESOLVCONF.CONF 5
 .Os
 .Sh NAME
@@ -190,6 +190,11 @@ directly:-
 Defaults to
 .Pa /etc/resolv.conf
 if not set.
+Set to
+.Pa /dev/null
+to stop
+.Xr resolvconf 8
+from changing it.
 .It Sy resolv_conf_options
 A list of libc resolver options, as specified in
 .Xr resolv.conf 5 .