[PATCH 4 of 5] xen.lowlevel.xl: Return None on empty domain name

[Marek Marczykowski <marmarek@mimuw.edu.pl>]

# HG changeset patch
# User Marek Marczykowski <marmarek@mimuw.edu.pl>
# Date 1307285583 -7200
# Node ID b77de60c85431593d439f2c4ac46023c6f8e5ee2
# Parent  f33981cd7d3df1718123cd364ee91a7bad064283
xen.lowlevel.xl: Return None on empty domain name

Previously PyString_FromString(NULL) was called, which caused assertion
failure.

Signed-off-by: Marek Marczykowski <marmarek@mimuw.edu.pl>

diff --git a/tools/python/xen/lowlevel/xl/xl.c b/tools/python/xen/lowlevel/xl/xl.c
--- a/tools/python/xen/lowlevel/xl/xl.c
+++ b/tools/python/xen/lowlevel/xl/xl.c
@@ -412,14 +412,16 @@ static PyObject *pyxl_domid_to_name(XlOb
 {
     char *domname;
     int domid;
-    PyObject *ret;
+    PyObject *ret = Py_None;
 
     if ( !PyArg_ParseTuple(args, "i", &domid) )
         return NULL;
 
     domname = libxl_domid_to_name(&self->ctx, domid);
-    ret = PyString_FromString(domname);
-    free(domname);
+    if (domname) {
+        ret = PyString_FromString(domname);
+        free(domname);
+    }
 
     return ret;
 }