[BUG, PATCH] xen-4.1-3 xend/XendDomainInfo.py#device_configure() TypeError

[Philipp Hahn <hahn@univention.de>]

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Hello,

I noticed a bug in Xen-4.1-3, which is also still present in xen+git.
I know that the Python xend is deprecated, but I'm stuck with xen-4.1 until xen is usable with libvirt, so my patch might still be helpful for others.
This is a follow-up to <http://lists.xen.org/archives/html/xen-users/2012-11/msg00069.html>, which still keeps me busy.

/xen/xend/server/SrvDomain.py declares, that "dev" is a string:
    def op_device_configure(self, _, req):
        return self.call(self.dom.device_configure,
                         [['config', 'sxpr'],
                          ['dev',    'str']],
                         req)

but in xen/xend/XendDomainInfo.py "devid" is expected to be an integer:
    def device_configure(self, dev_sxp, devid = None):
        """Configure an existing device.
...
        @param devid:      device id
        @type  devid:      int

This leads to an error when I try to change the media of an CDROM device:
ERROR (SrvBase:88) Request device_configure failed.
Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/xen/web/SrvBase.py", line 85, in perform
    return op_method(op, req)
  File "/usr/lib/python2.6/dist-packages/xen/xend/server/SrvDomain.py", line 216, in op_device_configure
    req)
  File "/usr/lib/python2.6/dist-packages/xen/xend/server/SrvDomain.py", line 186, in call
    return FormFn(fn, args)(req.args)
  File "/usr/lib/python2.6/dist-packages/xen/xend/Args.py", line 166, in __call__
    return self.call_with_form_args(self.fn, fargs, xargs=xargs)
  File "/usr/lib/python2.6/dist-packages/xen/xend/Args.py", line 138, in call_with_form_args
    return fn(*params, **keys)
  File "/usr/lib/python2.6/dist-packages/xen/xend/XendDomainInfo.py", line 1214, in device_configure
    raise VmError("Device %s not connected" % devid)
VmError: Device 768 not connected

This is because devid="768" != dev=768:
    def _getDeviceInfo_vbd(self, devid):
        for dev_type, dev_info in self.info.all_devices_sxpr():
            if dev_type != 'vbd' and dev_type != 'tap' and dev_type != 'tap2':
                continue
            dev = sxp.child_value(dev_info, 'dev')
            dev = dev.split(':')[0]
            dev = self.getDeviceController(dev_type).convertToDeviceNumber(dev)
            if devid == dev:
                return dev_info

After applying the attached patch, I can successfully change the media using libvirt:
# virsh change-media ucs31-64-hvm hda --eject --live --config
# virsh change-media ucs31-64-hvm hda /var/lib/libvirt/images/UCS_3.1-1-amd64.iso --live --config

Sincerely
Philipp Hahn
-- 
Philipp Hahn           Open Source Software Engineer      hahn@univention.de
Univention GmbH        be open.                       fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
                                                   http://www.univention.de/

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diff --git a/tools/python/xen/xend/XendDomainInfo.py b/tools/python/xen/xend/XendDomainInfo.py
index e9d3e7e..36dc599 100644
--- a/tools/python/xen/xend/XendDomainInfo.py
+++ b/tools/python/xen/xend/XendDomainInfo.py
@@ -1167,7 +1167,7 @@ class XendDomainInfo:
         @param dev_config: device configuration
         @type  dev_config: SXP object (parsed config)
         @param devid:      device id
-        @type  devid:      int
+        @type  devid:      str
         @return: Returns True if successfully updated device
         @rtype: boolean
         """
@@ -1193,24 +1193,24 @@ class XendDomainInfo:
 
         dev_control = self.getDeviceController(dev_class)
         if devid is None:
-            dev = dev_config.get('dev', '')
-            if not dev:
+            devid = dev_config.get('dev', '')
+            if not devid:
                 raise VmError('Block device must have virtual details specified')
-            if 'ioemu:' in dev:
-                (_, dev) = dev.split(':', 1)
+            if 'ioemu:' in devid:
+                (_, devid) = devid.split(':', 1)
             try:
-                (dev, _) = dev.split(':', 1)  # Remove ":disk" or ":cdrom"
+                (devid, _) = devid.split(':', 1)  # Remove ":disk" or ":cdrom"
             except ValueError:
                 pass
-            devid = dev_control.convertToDeviceNumber(dev)
-        dev_info = self._getDeviceInfo_vbd(devid)
+        dev = dev_control.convertToDeviceNumber(devid)
+        dev_info = self._getDeviceInfo_vbd(dev)
         if dev_info is None:
             raise VmError("Device %s not connected" % devid)
         dev_uuid = sxp.child_value(dev_info, 'uuid')
 
         if self.domid is not None:
             # use DevController.reconfigureDevice to change device config
-            dev_control.reconfigureDevice(devid, dev_config)
+            dev_control.reconfigureDevice(dev, dev_config)
         else:
             (_, new_b, new_f) = dev_control.getDeviceDetails(dev_config)
             if (new_f['device-type'] == 'cdrom' and
@@ -1220,7 +1220,7 @@ class XendDomainInfo:
                 pass
             else:
                 raise VmError('Refusing to reconfigure device %s:%d to %s' %
-                              (dev_class, devid, dev_config))
+                              (dev_class, dev, dev_config))
 
         # update XendConfig with new device info
         self.info.device_update(dev_uuid, dev_sxp)

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