Following should be sufficient to avoid the crash, but won't add a default
format, just point out the missing information

Daniel

--- src/storage_conf.c  17 Nov 2008 11:19:33 -0000      1.29
+++ src/storage_conf.c  4 Dec 2008 14:12:27 -0000
@@ -961,6 +961,11 @@
     ret->target.path = virXPathString(conn, "string(/volume/target/path)", ctxt);
     if (options->formatFromString) {
         char *format = virXPathString(conn, "string(/volume/target/format/@type)", ctxt);
+        if (format == NULL) {
+            virStorageReportError(conn, VIR_ERR_XML_ERROR,
+                          _("cannot guess missing format type for target"));
+            goto cleanup;
+        }
         if ((ret->target.format = (options->formatFromString)(format)) < 0) {
             virStorageReportError(conn, VIR_ERR_XML_ERROR,
                                   _("unknown volume format type %s"), format);

Created attachment 325691 [details]
Use default volume format to avoid crash

I cut this last night, seemed to fix the crash but I only did light testing. The patch is pretty simple though so I think it's safe.

Alright, fix for this was committed and in 0.5.1, so closing as CURRENTRELEASE.

libvirt-0.5.1-1.fc10 has been submitted as an update for Fedora 10.
http://admin.fedoraproject.org/updates/libvirt-0.5.1-1.fc10

libvirt-0.5.1-1.fc9 has been submitted as an update for Fedora 9.
http://admin.fedoraproject.org/updates/libvirt-0.5.1-1.fc9