From e75f5bfbe89e0ea4a98fb9b70fc4649fe861a21c Mon Sep 17 00:00:00 2001
From: Laine Stump <laine@laine.org>
Date: Fri, 17 Mar 2017 20:57:18 -0400
Subject: [PATCH] util: new function virNetDevGetMaster()

This function provides the bridge/bond device that the given network
device is attached to. The return value is 0 or -1, and the master
device is a char** argument to the function - this is needed in order
to allow for a "success" return from a device that has no master.
---
 src/libvirt_private.syms |  1 +
 src/util/virnetdev.c     | 49 ++++++++++++++++++++++++++++++++++++++++
 src/util/virnetdev.h     |  3 +++
 3 files changed, 53 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 57acfdbb19..b3fd6077e3 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1994,6 +1994,7 @@ virNetDevGetFeatures;
 virNetDevGetIndex;
 virNetDevGetLinkInfo;
 virNetDevGetMAC;
+virNetDevGetMaster;
 virNetDevGetMTU;
 virNetDevGetName;
 virNetDevGetOnline;
diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index 9e52a1f725..6805d324da 100644
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -979,6 +979,55 @@ int virNetDevGetIndex(const char *ifname ATTRIBUTE_UNUSED,
 #endif /* ! SIOCGIFINDEX */
 
 
+#if defined(__linux__) && defined(HAVE_LIBNL)
+/**
+ * virNetDevGetMaster:
+ * @ifname: name of interface we're interested in
+ * @master: used to return a string containing the name of @ifname's "master"
+ *          (this is the bridge or bond device that this device is attached to)
+ *
+ * Returns 0 on success, -1 on failure (if @ifname has no master
+ * @master will be NULL, but return value will still be 0 (success)).
+ */
+int
+virNetDevGetMaster(const char *ifname, char **master)
+{
+    int ret = -1;
+    void *nlData = NULL;
+    struct nlattr *tb[IFLA_MAX + 1] = {NULL, };
+
+    *master = NULL;
+
+    if (virNetlinkDumpLink(ifname, -1, &nlData, tb, 0, 0) < 0)
+        goto cleanup;
+
+    if (tb[IFLA_MASTER]) {
+        if (!(*master = virNetDevGetName(*(int *)RTA_DATA(tb[IFLA_MASTER]))))
+            goto cleanup;
+    }
+
+    ret = 0;
+ cleanup:
+    VIR_FREE(nlData);
+    return ret;
+}
+
+
+#else
+
+
+int
+virNetDevGetMaster(const char *ifname, char **master)
+{
+    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                   _("Unable to get device master from netlink on this platform"));
+    return -1;
+}
+
+
+#endif /* defined(__linux__) && defined(HAVE_LIBNL) */
+
+
 #if defined(SIOCGIFVLAN) && defined(HAVE_STRUCT_IFREQ) && HAVE_DECL_GET_VLAN_VID_CMD
 int virNetDevGetVLanID(const char *ifname, int *vlanid)
 {
diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h
index 01e9c5b954..2b1d0121de 100644
--- a/src/util/virnetdev.h
+++ b/src/util/virnetdev.h
@@ -165,6 +165,9 @@ int virNetDevGetIndex(const char *ifname, int *ifindex)
 int virNetDevGetVLanID(const char *ifname, int *vlanid)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
 
+int virNetDevGetMaster(const char *ifname, char **master)
+   ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
+
 int virNetDevValidateConfig(const char *ifname,
                             const virMacAddr *macaddr, int ifindex)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
-- 
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