Refactor networkSetIPv6Sysctls to remove repetition and reuse
of the 'field' variable.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
---
 src/network/bridge_driver.c | 71 ++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 36 deletions(-)

diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 713763130b..d817b5cbd6 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -2249,37 +2249,51 @@ networkEnableIPForwarding(bool enableIPv4,
 }
 
 
+static int
+networkSetIPv6Sysctl(const char *bridge,
+                     const char *sysctl_field,
+                     const char *sysctl_setting,
+                     bool ignoreMissing)
+{
+    g_autofree char *field = g_strdup_printf(SYSCTL_PATH "/net/ipv6/conf/%s/%s",
+                                             bridge, sysctl_field);
+
+    if (ignoreMissing && access(field, W_OK) < 0 && errno == ENOENT)
+        return -2;
+
+    if (virFileWriteStr(field, sysctl_setting, 0) < 0) {
+        virReportSystemError(errno,
+                             _("cannot write to '%s' on bridge '%s'"),
+                             field, bridge);
+        return -1;
+    }
+
+    return 0;
+}
+
+
 static int
 networkSetIPv6Sysctls(virNetworkObjPtr obj)
 {
     virNetworkDefPtr def = virNetworkObjGetDef(obj);
-    char *field = NULL;
-    int ret = -1;
     bool enableIPv6 = !!virNetworkDefGetIPByIndex(def, AF_INET6, 0);
+    int rc;
 
     /* set disable_ipv6 if there are no ipv6 addresses defined for the
      * network. But also unset it if there *are* ipv6 addresses, as we
      * can't be sure of its default value.
      */
-    field = g_strdup_printf(SYSCTL_PATH "/net/ipv6/conf/%s/disable_ipv6",
-                            def->bridge);
-
-    if (access(field, W_OK) < 0 && errno == ENOENT) {
+    rc = networkSetIPv6Sysctl(def->bridge, "disable_ipv6",
+                              enableIPv6 ? "0" : "1", true);
+    if (rc == -2) {
         if (!enableIPv6)
             VIR_DEBUG("ipv6 appears to already be disabled on %s",
                       def->bridge);
-        ret = 0;
-        goto cleanup;
+        return 0;
+    } else if (rc < 0) {
+        return -1;
     }
 
-    if (virFileWriteStr(field, enableIPv6 ? "0" : "1", 0) < 0) {
-        virReportSystemError(errno,
-                             _("cannot write to %s to enable/disable IPv6 "
-                               "on bridge %s"), field, def->bridge);
-        goto cleanup;
-    }
-    VIR_FREE(field);
-
     /* The rest of the ipv6 sysctl tunables should always be set the
      * same, whether or not we're using ipv6 on this bridge.
      */
@@ -2287,31 +2301,16 @@ networkSetIPv6Sysctls(virNetworkObjPtr obj)
     /* Prevent guests from hijacking the host network by sending out
      * their own router advertisements.
      */
-    field = g_strdup_printf(SYSCTL_PATH "/net/ipv6/conf/%s/accept_ra",
-                            def->bridge);
-
-    if (virFileWriteStr(field, "0", 0) < 0) {
-        virReportSystemError(errno,
-                             _("cannot disable %s"), field);
-        goto cleanup;
-    }
-    VIR_FREE(field);
+    if (networkSetIPv6Sysctl(def->bridge, "accept_ra", "0", false) < 0)
+        return -1;
 
     /* All interfaces used as a gateway (which is what this is, by
      * definition), must always have autoconf=0.
      */
-    field = g_strdup_printf(SYSCTL_PATH "/net/ipv6/conf/%s/autoconf", def->bridge);
+    if (networkSetIPv6Sysctl(def->bridge, "autoconf", "0", false) < 0)
+        return -1;
 
-    if (virFileWriteStr(field, "0", 0) < 0) {
-        virReportSystemError(errno,
-                             _("cannot disable %s"), field);
-        goto cleanup;
-    }
-
-    ret = 0;
- cleanup:
-    VIR_FREE(field);
-    return ret;
+    return 0;
 }
 
 
-- 
2.25.4

On Wed, 2020-07-15 at 23:27 +0200, Ján Tomko wrote:
> Refactor networkSetIPv6Sysctls to remove repetition and reuse
> of the 'field' variable.
> 
> Signed-off-by: Ján Tomko <jtomko@redhat.com>
> ---
>  src/network/bridge_driver.c | 71 ++++++++++++++++++-------------------
>  1 file changed, 35 insertions(+), 36 deletions(-)

Reviewed-by: Andrea Bolognani <abologna@redhat.com>

-- 
Andrea Bolognani / Red Hat / Virtualization