On Wed, Jul 30, 2008 at 03:57:57PM +0100, Daniel P. Berrange wrote:
On Wed, Jul 30, 2008 at 03:49:17PM +0100, Richard W.M. Jones wrote:
This patch changes the implementations lots of functions which parse XML documents, so that if the XML document is not well-formed then we get detailed error messages.
The general form of the change is:
static void catchXMLError (void *ctx, const char *msg ATTRIBUTE_UNUSED, ...) { // a callback which calls virDomainReportError }
virDomainDefPtr virDomainDefParseString(virConnectPtr conn, virCapsPtr caps, const char *xmlStr) { xmlParserCtxtPtr pctxt;
pctxt = xmlNewParserCtxt (); pctxt->sax->error = catchXMLError;
xml = xmlCtxtReadDoc (pctxt, //...) etc.
There are some unavoidable shortcomings:
(1) There is no place to stash user pointers during the callback (the suggestively named pctxt->userData field is already used for something else), so we cannot pass the virConnectPtr to the error function. As a result, virterror will store the error in a global variable, and callers will probably not be able to access it.
void *_private; /* For user data, libxml won't touch it */ just set _private in the parser context, you should get the parser context back in the SAX handler, then you can get to your _private data. that should work and avoid the mess of global variables and thread stuff...
(2) The XML parser routinely produces multiple error messages, and virterror throws away all but the last one.
It'd probably be more use to only report the first one, since the latter problems may well be caused by earlier problems.
Likely but not always correct, maybe the solution is to build a big string concatenating all the errors and passing it back
You won't see those except with the 'test' or 'xen' drivers run locally. Anything going via the daemon will be output on the daemon's stderr (/dev/null) and not on the client.
yeah, unfortunately we have to assume a model where each errors can't be reported individually, Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/