tools/xend: check for device model if path is not specified

this is the patch to check for device model (in XendConfig.py) when the
device_model had no path specified, i.e. XenD was trying to read the
file on the auxbin path. Without this patch applied the meaningless
python error "coercing to Unicode: need string or buffer, NoneType
found" occurred:

[2010-11-30 13:56:47 5255] ERROR (xmlrpclib2:181) Internal error
handling xend.domain.create
Traceback (most recent call last):
   File "/usr/lib64/python2.4/site-packages/xen/util/xmlrpclib2.py",
line 134, in _marshaled_dispatch
     response = self._dispatch(method, params)
   File "/usr/lib64/python2.4/SimpleXMLRPCServer.py", line 406, in _dispatch
     return func(*params)
   File
"/usr/lib64/python2.4/site-packages/xen/xend/server/XMLRPCServer.py",
line 80, in domain_create
     info = XendDomain.instance().domain_create(config)
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomain.py",
line 1001, in domain_create
     dominfo = XendDomainInfo.create(config)
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py",
line 97, in create
     domconfig = XendConfig.XendConfig(sxp_obj = config)
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendConfig.py",
line 367, in __init__
     self.validate()
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendConfig.py",
line 558, in validate
     self._platform_sanity_check()
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendConfig.py",
line 502, in _platform_sanity_check
     if not os.path.exists(self['platform']['device_model']):
   File "/usr/lib64/python2.4/posixpath.py", line 171, in exists
     st = os.stat(path)
TypeError: coercing to Unicode: need string or buffer, NoneType found

This patch raises VmError with message that no valid device model was
specified if None type was found in the device_model specification.

It's been tested on non-existing device model where the message is being
printed. If an invalid (but existing) device_model is set in the
configuration file the domain was destroyed because it crashed. If there
is a path specified (i.e. it's not using auxbin path) it bails with
error that the device model was not found (which was already implemented
there).

Signed-off-by: Michal Novotny <minovotn@redhat.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/tools/python/xen/xend/XendConfig.py b/tools/python/xen/xend/XendConfig.py
index 4181d6cf3c..5568d353e5 100644
--- a/tools/python/xen/xend/XendConfig.py
+++ b/tools/python/xen/xend/XendConfig.py
@@ -498,6 +498,10 @@ class XendConfig(dict):
             if os.path.dirname(self['platform']['device_model']) == "":
                 self['platform']['device_model'] = \
                     auxbin.pathTo(self['platform']['device_model'])
+            # If the device_model is not set the os.path.exists() would raise
+            # an exception so we return our error message instead if applicable
+            if not self['platform']['device_model']:
+                raise VmError("No valid device model specified")
             if not os.path.exists(self['platform']['device_model']):
                 raise VmError("device model '%s' not found" % str(self['platform']['device_model']))