[Libvir] XML escaping patch

This is related to bug #206653 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=206653 basically we are very optimistic when generating the XML files, and sometimes this can break. The most common case is if some string inherited from the user input or some other config file embeds one of > < or & , another one would be if the strings are containing character outside of ACSII range and not encoded in UTF-8. We can at least cope with the easy case of escaping the 3 characters. This patch adds a simple buffer printing routing working with a simple string argument, and use it for the 2 cases where I think it's most likely to be needed i.e. cmdline and bootloader_args. There is a number of places where paths are used and the user might use weird character names, but since those cases can't be handled properly (you can't change that path or try to convert encoding on the fly since we can't guess reliably which one is used) I didn't tried to change those. This makes for a relatively simple patch which should IMHO cover most case where we may break while we really should not. Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/