The dom destroy path is doing a dom_get on a non-existent domain to

ensure it is non-existent.  This changes throws an explicit exception  
when xc_domain_getinfo returns an error, instead of triggering an  
internal python error.  It then handles the exception in dom_get by  
returning None, which callers already expect to mean failure.

Signed-off-by: Robert Read <robert@xensource.com>

tools/python/xen/lowlevel/xc/xc.c

@@ -220,6 +220,9 @@ static PyObject *pyxc_domain_getinfo(PyObject *self,
         return PyErr_NoMemory();
 
     nr_doms = xc_domain_getinfo(xc->xc_handle, first_dom, max_doms, info);
+
+    if (nr_doms < 0)
+        return PyErr_SetFromErrno(xc_error);
     
     list = PyList_New(nr_doms);
     for ( i = 0 ; i < nr_doms; i++ )

tools/python/xen/xend/XendDomainInfo.py

@@ -110,9 +110,13 @@ def dom_get(dom):
     @param dom: domain id
     @return: info or None
     """
-    domlist = xc.domain_getinfo(dom, 1)
-    if domlist and dom == domlist[0]['dom']:
-        return domlist[0]
+    try:
+        domlist = xc.domain_getinfo(dom, 1)
+        if domlist and dom == domlist[0]['dom']:
+            return domlist[0]
+    except Exception, err:
+        # ignore missing domain
+        log.exception("domain_getinfo(%d) failed, ignoring", dom)
     return None
 
 class XendDomainInfo: