On Tue, Aug 26, 2014 at 09:34:42AM +0300, Shahar Havivi wrote:
Hi,
I am trying to add xmlXPathRegisterNs() to v2v/xml-c.c but I get a seg fault, the signature should be: http://xmlsoft.org/html/libxml-xpathInternals.html#xmlXPathRegisterNs
I think I am wrong in CAMLparam and CAMLlocal..., Following is the patch:
=================================================================================== diff --git a/v2v/xml-c.c b/v2v/xml-c.c index 4c9bc77..a917c24 100644 --- a/v2v/xml-c.c +++ b/v2v/xml-c.c @@ -141,6 +141,16 @@ v2v_xml_xpath_new_context (value docv) }
value +v2v_xml_xpath_register_ns (value prefix, value uri, value xpathctx) +{ + CAMLparam3 (prefix, uri, xpathctx); + CAMLlocal1 (retval); + retval = xmlXPathRegisterNs (BAD_CAST String_val (prefix), BAD_CAST String_val (uri), xpathctx); + + CAMLreturn (retval);
An 'int' isn't a 'value', so this will not work and likely segfault. For the representation of 'value' see: http://rwmj.wordpress.com/2009/08/04/ocaml-internals/#content (and follow up articles). In any case, here you need to turn the return value into an exception, ie something like this untested code: value v2v_xml_xpath_register_ns (value prefix, value uri, value xpathctx) { CAMLparam3 (prefix, uri, xpathctx); int r; r = xmlXPathRegisterNs (...); if (r == -1) caml_invalid_argument ("some suitable error message here ..."); /* return unit */ CAMLreturn (Val_unit); }
+external xpath_register_ns : string -> string -> xpathctx -> int = "v2v_xml_xpath_register_ns"
Needs to return unit, not int. If the libxml2 function returns -1 then this will throw an exception (Invalid_arg).
+val xpath_register_ns : string -> string -> xpathctx -> int +(** xmlXPathRegisterNs *)
Same here. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/