Re: [Libvirt-cim] [PATCH] Make xmlgen.c use libxml2 instead of hacking it out manually
On Tue, Dec 02, 2008 at 08:43:48AM -0800, Dan Smith wrote:
# HG changeset patch
# User Dan Smith <danms(a)us.ibm.com>
# Date 1228236226 28800
# Node ID c34ae7c0ded8870aeba40a0798ac31f1ea2c5bbd
# Parent 6e8a488cf67b47efb618c28aa2a9104d5b0e1b91
Make xmlgen.c use libxml2 instead of hacking it out manually
Now that our XML generation is getting complex enough, I think it's worth
using libxml2 to build a proper DOM tree and XML string.
Note that due to the invasiveness of this patch, it's almost unreadable. It
may be easier to review after it's applied to the tree. Also, it deserves
some serious review and testing for correctness and error-handling abilities.
Comments on this approach are welcome too, of course.
up to here no real comment about the libxml2 API usage :-)
+char *device_to_xml(struct virt_device *dev)
+{
[...]
+ doc = xmlNewDoc(BAD_CAST "1.0");
+ if (doc == NULL)
+ goto out;
+ root = xmlNewNode(NULL, BAD_CAST "tmp");
+ if (root == NULL)
+ goto out;
okay you need to build a root, surprizing but okay
[...]
+ msg = func(root, dominfo);
+ if (msg != NULL) {
+ CU_DEBUG("Failed to create device XML: %s", msg);
+ goto out;
+ }
+
+ xmlDocSetRootElement(doc, root->children);
+
+ xmlDocDumpFormatMemory(doc, &_xml, &xml_size, 1);
+ xml = strdup((char *)_xml);
+ xmlFree(_xml);
ouch it hurts a bit. In general I would rather suggest to use the new
xmlsave APIs http://xmlsoft.org/html/libxml-xmlsave.html
since you rely on the indenting, and hence some of the saving options
- create an xmlBufferPtr (xmlNewBuffer IIRC)
- http://xmlsoft.org/html/libxml-xmlsave.html#xmlSaveToBuffer
with XML_SAVE_FORMAT option
- http://xmlsoft.org/html/libxml-xmlsave.html#xmlSaveTree
- http://xmlsoft.org/html/libxml-xmlsave.html#xmlSaveClose
- then grab the string from the buffer and free the buffer
it's a bit more complex but gives you more control over the saving in
the long run, which may be useful. Could be encapsulated as a generic
node serialization routine if you plan to do this many times.
+ xmlDocDumpFormatMemory(doc, &_xml, &xml_len, 1);
+ if (_xml == NULL)
+ goto out;
+
+ xml = strdup((char *)_xml);
+ if (xml == NULL)
+ msg = "Out of memory generating XML";
+ else
+ msg = NULL;
similar here but with
http://xmlsoft.org/html/libxml-xmlsave.html#xmlSaveDoc
instead of xmlSaveTree()
yours :-)
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel(a)veillard.com | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/