From 18a9b144be17afca1a5bdb9d1142e6dbf201d8a7 Mon Sep 17 00:00:00 2001
From: zhangqiang <zhangqiang@kylinos.cn>
Date: Mon, 7 Nov 2022 07:14:11 +0800
Subject: [PATCH] Incorrect processing of empty files for resolv.conf When
 resolv.conf is empty or does not exist,ifup-post backup files that do not
 match expectations.

---
 network-scripts/ifup              |  2 ++
 network-scripts/network-functions | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/network-scripts/ifup b/network-scripts/ifup
index a053077..8871526 100755
--- a/network-scripts/ifup
+++ b/network-scripts/ifup
@@ -50,6 +50,8 @@ if [ ${UID} != 0 ]; then
     exit 1
 fi
 
+init_resolv_conf 
+
 source_config
 
 if ! is_true ${DEPRECATION_WARNING_ISSUED}; then
diff --git a/network-scripts/network-functions b/network-scripts/network-functions
index eed3c91..83e4bea 100644
--- a/network-scripts/network-functions
+++ b/network-scripts/network-functions
@@ -633,6 +633,29 @@ is_bonding_device ()
     [ -f "/sys/class/net/$1/bonding/slaves" ]
 }
 
+# Initialize /etc/resolv.conf when the network service starts
+init_resolv_conf ()
+{
+    title="# Generated by network"
+    if [ ! -f /etc/resolv.conf ];then
+        echo ${title} > /etc/resolv.conf
+        return 0
+    fi
+    #If the file exists and the content is empty or there are empty lines, the ifup-post condition will be judged wrongly,
+    #and the backup process will be started. Add a comment at the first line here to solve the problem
+    if ! grep -E -q "${title}" /etc/resolv.conf;then
+        if tmp_file=$(mktemp);then
+            echo ${title} > ${tmp_file}
+            cat /etc/resolv.conf >> ${tmp_file}
+            cp -rf ${tmp_file} /etc/resolv.conf
+            /usr/bin/logger -p local7.notice -t "NET" -i "$0 : updated ${title} to /etc/resolv.conf"
+            rm -rf ${tmp_file}
+        else
+            /usr/bin/logger -p local7.err -t "NET" -i "$0 : /etc/resolv.conf was not updated ${title}: failed to create temporary file"
+	fi
+    fi
+}
+
 # Invoke this when /etc/resolv.conf has changed:
 change_resolv_conf ()
 {
-- 
2.27.0