Only update resolv.conf if changed (avoid logspam)

[project/netifd.git] / interface-ip.c

diff --git a/interface-ip.c b/interface-ip.c
index df2904f..fc5a4a3 100644 (file)
--- a/interface-ip.c
+++ b/interface-ip.c
@@ -781,10 +781,11 @@ interface_write_resolv_conf(void)
        struct interface *iface;
        char *path = alloca(strlen(resolv_conf) + 5);
        FILE *f;
+       uint32_t crcold, crcnew;
 
        sprintf(path, "%s.tmp", resolv_conf);
        unlink(path);
-       f = fopen(path, "w");
+       f = fopen(path, "w+");
        if (!f) {
                D(INTERFACE, "Failed to open %s for writing\n", path);
                return;
@@ -805,8 +806,21 @@ interface_write_resolv_conf(void)
                if (!iface->proto_ip.no_dns)
                        write_resolv_conf_entries(f, &iface->proto_ip);
        }
+       fflush(f);
+       rewind(f);
+       crcnew = crc32_file(f);
        fclose(f);
-       if (rename(path, resolv_conf) < 0) {
+
+       crcold = crcnew + 1;
+       f = fopen(resolv_conf, "r");
+       if (f) {
+               crcold = crc32_file(f);
+               fclose(f);
+       }
+
+       if (crcold == crcnew) {
+               unlink(path);
+       } else if (rename(path, resolv_conf) < 0) {
                D(INTERFACE, "Failed to replace %s\n", resolv_conf);
                unlink(path);
        }