details: Disable snapshot buttons if conn or guest doesn't have support

tests/testdriver.xml

@@ -356,6 +356,7 @@ test-many-devices, like an alternate RNG.
     <disk type='file' device='disk'>
       <source file='/dev/default-pool/test-clone-simple.img'/>
       <target dev='hda' bus='ide'/>
+      <driver type="qcow2"/>
     </disk>
     <interface type='user'>
       <mac address='22:11:11:11:11:11'/>

ui/details.ui

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.16.0 on Mon Sep 30 15:08:28 2013 -->
+<!-- Generated with glade 3.16.0 on Mon Sep 30 20:26:08 2013 -->
 <interface>
   <!-- interface-requires gtk+ 3.0 -->
   <object class="GtkAccelGroup" id="accelgroup1"/>
@@ -391,7 +391,6 @@
                   <object class="GtkRadioToolButton" id="control-snapshots">
                     <property name="visible">True</property>
                     <property name="can_focus">False</property>
-                    <property name="tooltip_text" translatable="yes">Manage VM snapshots</property>
                     <property name="label" translatable="yes">Snapshots</property>
                     <property name="icon_name">vm_clone_wizard</property>
                     <property name="group">control-vm-console</property>

virtManager/details.py

@@ -1335,10 +1335,17 @@ class vmmDetails(vmmGObjectUI):
 
         details = self.widget("details-pages")
         self.page_refresh(details.get_current_page())
-
-        # This is safe to refresh, and is dependent on domain state
         self._refresh_runtime_pinning()
 
+        errmsg = self.vm.snapshots_supported()
+        cansnap = not bool(errmsg)
+        self.widget("control-snapshots").set_sensitive(cansnap)
+        self.widget("details-menu-view-snapshots").set_sensitive(cansnap)
+        tooltip = _("Manage VM snapshots")
+        if not cansnap:
+            tooltip += "\n" + errmsg
+        self.widget("control-snapshots").set_tooltip_text(tooltip)
+
 
     #############################
     # External action listeners #

virtManager/domain.py

@@ -242,7 +242,6 @@ class vmmDomain(vmmLibvirtObject):
 
         self.managedsave_supported = False
         self.remote_console_supported = False
-        self.snapshots_supported = False
         self.title_supported = False
 
         self._enable_net_poll = False
@@ -265,16 +264,6 @@ class vmmDomain(vmmLibvirtObject):
             snap.cleanup()
         self._snapshot_list = None
 
-    def _get_getvcpus_supported(self):
-        return self.conn.check_domain_support(self._backend,
-                                            self.conn.SUPPORT_DOMAIN_GETVCPUS)
-    getvcpus_supported = property(_get_getvcpus_supported)
-
-    def _get_getjobinfo_supported(self):
-        return self.conn.check_domain_support(self._backend,
-                                            self.conn.SUPPORT_DOMAIN_JOB_INFO)
-    getjobinfo_supported = property(_get_getjobinfo_supported)
-
     def _libvirt_init(self):
         """
         Initialization to do if backed by a libvirt virDomain
@@ -285,9 +274,6 @@ class vmmDomain(vmmLibvirtObject):
         self.remote_console_supported = self.conn.check_domain_support(
                                     self._backend,
                                     self.conn.SUPPORT_DOMAIN_CONSOLE_STREAM)
-        self.snapshots_supported = self.conn.check_domain_support(
-                                    self._backend,
-                                    self.conn.SUPPORT_DOMAIN_LIST_SNAPSHOTS)
         self.title_supported = self.conn.check_domain_support(
                                     self._backend,
                                     self.conn.SUPPORT_DOMAIN_GET_METADATA)
@@ -405,6 +391,44 @@ class vmmDomain(vmmLibvirtObject):
             return "-"
         return str(i)
 
+    ##################
+    # Support checks #
+    ##################
+
+    def _get_getvcpus_supported(self):
+        return self.conn.check_domain_support(self._backend,
+                                            self.conn.SUPPORT_DOMAIN_GETVCPUS)
+    getvcpus_supported = property(_get_getvcpus_supported)
+
+    def _get_getjobinfo_supported(self):
+        return self.conn.check_domain_support(self._backend,
+                                             self.conn.SUPPORT_DOMAIN_JOB_INFO)
+    getjobinfo_supported = property(_get_getjobinfo_supported)
+
+    def snapshots_supported(self):
+        if not self.conn.check_domain_support(
+            self._backend, self.conn.SUPPORT_DOMAIN_LIST_SNAPSHOTS):
+            return _("Libvirt connection does not support snapshots.")
+
+        if self.list_snapshots():
+            return
+
+        # Check if our disks are all qcow2
+        seen_qcow2 = False
+        for disk in self.get_disk_devices(refresh_if_nec=False):
+            if disk.read_only:
+                continue
+            if not disk.path:
+                continue
+            if disk.driver_type == "qcow2":
+                seen_qcow2 = True
+                continue
+            return _("Snapshots are only supported if all writeable disks "
+                     "images allocated to the guest are qcow2 format.")
+        if not seen_qcow2:
+            return _("Snapshots require at least one writeable qcow2 disk "
+                     "image allocated to the guest.")
+
 
     #############################
     # Internal XML handling API #

virtManager/snapshots.py

@@ -155,11 +155,6 @@ class vmmSnapshotPage(vmmGObjectUI):
         model = self.widget("snapshot-list").get_model()
         model.clear()
 
-        if not self.vm.snapshots_supported:
-            self._set_error_page(_("Libvirt connection does not support "
-                                  "snapshots."))
-            return
-
         try:
             snapshots = self.vm.list_snapshots()
         except Exception, e: