[libvirt] [PATCH] esx: Fix dynamic VI object type detection

[Matthias Bolte]

VI objects support inheritance with subtype polymorphism. For example the
FileInfo object type is extended by FloppyImageFileInfo, FolderFileInfo
etc. Then SearchDatastore_Task returns an array of FileInfo objects and
depending on the represented file the FileInfo is actually a FolderFileInfo
or FloppyImageFileInfo etc. The actual type information is stored as XML
attribute that allows clients such as libvirt to distinguish between the
actual types. esxVI_GetActualObjectType is used to extract the actual type.

I assumed that this mechanism would be used for all VI object types that
have subtypes. But this is not the case. It seems only to be used for types
that are actually used as generic base type such as FileInfo. But it is not
used for types that got extended later such as ElementDescription that was
extended by ExtendedElementDescription (added in vSphere API 4.0) or that
are not meant to be used with subtype polymorphism.

This breaks the deserialization of types that contain ElementDescription
properties such as PerfCounterInfo or ChoiceOption, because the code
expects an ElementDescription object to have an XML attribute named type
that is not present, since ExtendedElementDescription was added to the
esx_vi_generator.input in commit 60f0f55ee4686fecbffc5fb32f90863427d02a14.
This in turn break virtual machine question handling and auto answering.

Fix this by using the base type if no XML type attribute is present.
---
 src/esx/esx_vi_types.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/esx/esx_vi_types.c b/src/esx/esx_vi_types.c
index 1a26556..c55396c 100644
--- a/src/esx/esx_vi_types.c
+++ b/src/esx/esx_vi_types.c
@@ -720,10 +720,9 @@ esxVI_GetActualObjectType(xmlNodePtr node, esxVI_Type baseType,
                       BAD_CAST "http://www.w3.org/2001/XMLSchema-instance");
 
     if (type == NULL) {
-        virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("%s is missing 'type' property"),
-                       esxVI_Type_ToString(baseType));
-        return -1;
+        // no actual type specified, use base type instead
+        *actualType = baseType;
+        return 0;
     }
 
     *actualType = esxVI_Type_FromString(type);
-- 
1.7.9.5