[Libguestfs] [PATCH] Improve error message when LibvirtXML is given invalid domain XML

[Matthew Booth]

If a user accidentally passed a valid XML document to the LibvirtXML which
wasn't actually a libvirt domain XML document, they would end up getting obtuse
errors from a libguestfs library. This change does 2 sanity checks:

1. After parsing a the XML document, check /domain/name exists.
2. Check that the domain defines some storage

The second check is generally useful, as we can't usefully do anything with a
domain which has no storage.
---
 lib/Sys/VirtV2V/Connection.pm            |    3 +++
 lib/Sys/VirtV2V/Connection/LibVirtXML.pm |    5 +++++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/lib/Sys/VirtV2V/Connection.pm b/lib/Sys/VirtV2V/Connection.pm
index da6a44b..4dc659d 100644
--- a/lib/Sys/VirtV2V/Connection.pm
+++ b/lib/Sys/VirtV2V/Connection.pm
@@ -186,6 +186,9 @@ sub _storage_iterate
         $source_e->setAttribute($source->getName(), '');
     }
 
+    die(user_message(__("Guest doesn't define any recognised storage devices")))
+        unless (@paths > 0);
+
     $self->{paths} = \@paths;
     $self->{devices} = \@devices;
 }
diff --git a/lib/Sys/VirtV2V/Connection/LibVirtXML.pm b/lib/Sys/VirtV2V/Connection/LibVirtXML.pm
index 729f1e8..ac3e82b 100644
--- a/lib/Sys/VirtV2V/Connection/LibVirtXML.pm
+++ b/lib/Sys/VirtV2V/Connection/LibVirtXML.pm
@@ -95,6 +95,11 @@ sub _get_dom
     # Display any parse errors
     die(user_message(__x("Unable to parse domain from file {path}: {error}",
                          path => $self->{path}, error => $@))) if ($@);
+
+    # Check it looks like domain XML
+    my ($dummy) = $self->{dom}->findnodes('/domain/name');
+    die(user_message(__x("{path} doesn't look like a libvirt domain XML file",
+                         path => $self->{path}))) unless (defined($dummy));
 }
 
 =back
-- 
1.7.1