[PATCH 2/3] virsh: prevent destroying a in-used network for net-destroy

[Lin Ma <lma@xxxxxxxx>]

* add --system flag for net-dumpxml to show information about the
  attached interfaces of the virtual network.

* call virNetworkGetXMLDesc in cmdNetworkDestroy to get the live state
  info to check whether the virtual network is in use.

* add --force flag for net-destroy to forcibly destroy the virtual
  network even if it's in use.

Signed-off-by: Lin Ma <lma@xxxxxxxx>
---
 tools/virsh-network.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++----
 tools/virsh.pod       |  8 +++++--
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/tools/virsh-network.c b/tools/virsh-network.c
index 5f8743c..17a5710 100644
--- a/tools/virsh-network.c
+++ b/tools/virsh-network.c
@@ -253,6 +253,10 @@ static const vshCmdOptDef opts_network_destroy[] = {
      .flags = VSH_OFLAG_REQ,
      .help = N_("network name or uuid")
     },
+    {.name = "force",
+     .type = VSH_OT_BOOL,
+     .help = N_("Forcefully stop a given network")
+    },
     {.name = NULL}
 };
 
@@ -260,20 +264,55 @@ static bool
 cmdNetworkDestroy(vshControl *ctl, const vshCmd *cmd)
 {
     virNetworkPtr network;
-    bool ret = true;
+    bool ret = false;
     const char *name;
+    char *br_xml = NULL;
+    xmlDocPtr xml_doc = NULL;
+    xmlXPathContextPtr ctxt = NULL;
 
     if (!(network = vshCommandOptNetwork(ctl, cmd, &name)))
-        return false;
+        goto cleanup;
+
+#ifdef WITH_NETCF
+    if (!vshCommandOptBool(cmd, "force")) {
+        if (virNetworkIsActive(network) <= 0) {
+            vshError(ctl, "%s", _("network is not active"));
+            goto cleanup;
+        }
+        if (!(br_xml = virNetworkGetXMLDesc(network,
+                                            VIR_NETWORK_XML_IFACE_ATTACHED)))
+            goto cleanup;
+
+        if (!(xml_doc = virXMLParseStringCtxt(br_xml,
+                                              _("(bridge interface "
+                                                "definition)"), &ctxt))) {
+            vshError(ctl, "%s", _("Failed to parse network configuration"));
+            goto cleanup;
+        }
+
+        if (virXPathNode("./bridge/interface[1]", ctxt) != NULL) {
+            vshError(ctl, "%s", _("The network is in use by guests"));
+            vshPrint(ctl, "%s", _("Use --force flag if you do want to do so"));
+            goto cleanup;
+        }
+    }
+#endif
 
     if (virNetworkDestroy(network) == 0) {
         vshPrint(ctl, _("Network %s destroyed\n"), name);
     } else {
         vshError(ctl, _("Failed to destroy network %s"), name);
-        ret = false;
+        goto cleanup;
     }
 
-    virNetworkFree(network);
+    ret = true;
+ cleanup:
+    if(network)
+        virNetworkFree(network);
+    VIR_FREE(br_xml);
+    xmlXPathFreeContext(ctxt);
+    xmlFreeDoc(xml_doc);
+
     return ret;
 }
 
@@ -300,6 +339,10 @@ static const vshCmdOptDef opts_network_dumpxml[] = {
      .type = VSH_OT_BOOL,
      .help = N_("network information of an inactive domain")
     },
+    {.name = "system",
+     .type = VSH_OT_BOOL,
+     .help = N_("current live state information including attached interfaces")
+    },
     {.name = NULL}
 };
 
@@ -311,6 +354,7 @@ cmdNetworkDumpXML(vshControl *ctl, const vshCmd *cmd)
     char *dump;
     unsigned int flags = 0;
     int inactive;
+    bool system = false;
 
     if (!(network = vshCommandOptNetwork(ctl, cmd, NULL)))
         return false;
@@ -319,6 +363,16 @@ cmdNetworkDumpXML(vshControl *ctl, const vshCmd *cmd)
     if (inactive)
         flags |= VIR_NETWORK_XML_INACTIVE;
 
+    system = vshCommandOptBool(cmd, "system");
+    if (system) {
+        flags = VIR_NETWORK_XML_IFACE_ATTACHED;
+        if (virNetworkIsActive(network) <= 0) {
+            vshError(ctl, "%s", _("--system only works on active network"));
+            virNetworkFree(network);
+            return false;
+        }
+    }
+
     dump = virNetworkGetXMLDesc(network, flags);
 
     if (dump != NULL) {
diff --git a/tools/virsh.pod b/tools/virsh.pod
index 804458e..3373ada 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -2672,16 +2672,20 @@ to get a description of the XML network format used by libvirt.
 Define a persistent virtual network from an XML I<file>, the network is just
 defined but not instantiated (started).
 
-=item B<net-destroy> I<network>
+=item B<net-destroy> I<network>  [I<--force>]
 
 Destroy (stop) a given transient or persistent virtual network
 specified by its name or UUID. This takes effect immediately.
+If I<--force> is specified, then forcefully destroy the virtual
+network even if it's in use.
 
-=item B<net-dumpxml> I<network> [I<--inactive>]
+=item B<net-dumpxml> I<network> [I<--inactive>] [I<--system>]
 
 Output the virtual network information as an XML dump to stdout.
 If I<--inactive> is specified, then physical functions are not
 expanded into their associated virtual functions.
+If I<--system> is specified, then directly output the current
+live state corresponding to this network from system.
 
 =item B<net-edit> I<network>
 
-- 
1.8.4

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