1:34 a.m.
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);
+}
+
+value
v2v_xml_xpath_eval_expression (value xpathctxv, value exprv)
{
CAMLparam2 (xpathctxv, exprv);
diff --git a/v2v/xml.ml b/v2v/xml.ml
index 78cb022..2e4d222 100644
--- a/v2v/xml.ml
+++ b/v2v/xml.ml
@@ -31,6 +31,7 @@ type node = doc * node_ptr
external parse_memory : string -> doc = "v2v_xml_parse_memory"
external xpath_new_context : doc -> xpathctx = "v2v_xml_xpath_new_context"
external xpath_eval_expression : xpathctx -> string -> xpathobj =
"v2v_xml_xpath_eval_expression"
+external xpath_register_ns : string -> string -> xpathctx -> int =
"v2v_xml_xpath_register_ns"
external xpathobj_nr_nodes : xpathobj -> int = "v2v_xml_xpathobj_nr_nodes"
external xpathobj_get_node_ptr : xpathobj -> int -> node_ptr =
"v2v_xml_xpathobj_get_node_ptr"
diff --git a/v2v/xml.mli b/v2v/xml.mli
index 38bb9cd..cab4395 100644
--- a/v2v/xml.mli
+++ b/v2v/xml.mli
@@ -29,6 +29,8 @@ val xpath_new_context : doc -> xpathctx
(** xmlXPathNewContext *)
val xpath_eval_expression : xpathctx -> string -> xpathobj
(** xmlXPathEvalExpression *)
+val xpath_register_ns : string -> string -> xpathctx -> int
+(** xmlXPathRegisterNs *)
val xpathobj_nr_nodes : xpathobj -> int
(** Get the number of nodes in the node set of the xmlXPathObjectPtr. *)
===================================================================================
2:10 a.m.
Hi,
On Tuesday 26 August 2014 09:34:42 Shahar Havivi wrote:
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);
+}
+
First of all, you are using the xpathctx parameter directly as
parameter for xmlXPathRegisterNs, while it is an OCaml value which
wraps the actual object; see how it is done in e.g.
v2v_xml_xpath_eval_expression, using the Xpathctx_val macro.
Second, the order of the arguments in your xmlXPathRegisterNs is wrong:
- yours: xmlXPathRegisterNs(prefix, uri, ctxt)
- actual function: xmlXPathRegisterNs(ctxt, prefix, uri)
--
Pino Toscano
2:38 a.m.
On Tue, Aug 26, 2014 at 09:10:11AM +0200, Pino Toscano wrote:
Hi,
On Tuesday 26 August 2014 09:34:42 Shahar Havivi wrote:
> 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);
> +}
> +
First of all, you are using the xpathctx parameter directly as
parameter for xmlXPathRegisterNs, while it is an OCaml value which
wraps the actual object; see how it is done in e.g.
v2v_xml_xpath_eval_expression, using the Xpathctx_val macro.
Second, the order of the arguments in your xmlXPathRegisterNs is wrong:
- yours: xmlXPathRegisterNs(prefix, uri, ctxt)
- actual function: xmlXPathRegisterNs(ctxt, prefix, uri)
This too.
Notice that Val_foo() means convert foo to value, and
Foo_val() means convert value to foo.
In that file, only node_ptr/xmlNodePtr can be cast directly from value
to the C type, and that's for a very special and peculiar reason. For
everything else you have to convert between value and the C type (and
vice versa) using the appropriate macro.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v
2:33 a.m.
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/
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3 comments
3 participants
participants (3)
-
Pino Toscano -
Richard W.M. Jones -
Shahar Havivi