Re: [xml] errors management

[Rush Manbert <rush manbert com>]

On Nov 13, 2008, at 6:22 AM, Francesco Gennai wrote:

> Hi,
>
> I would like to capture any error from LIBXML API
> and (if possible) have it in memory to process it
> in my own error/debug routines.
>
> Here is an example of code that can returns more than one error line.
>
>            pctxt.userData = (void *) stderr;
>            pctxt.error    = (xmlValidityErrorFunc) fprintf;
>            pctxt.warning  = (xmlValidityWarningFunc) fprintf;
>            if (!xmlValidateDtd(&pctxt, pdoc, pdtd)) {
>                xmlGenericError(xmlGenericErrorContext,
>                        "Document %s does not validate against %s\n",
>                        xmlFile, dtdFile);
>
> such as:
>
> No declaration for element dst
> No declaration for attribute id of element dst
> attribute ref line 5 references an unknown ID "foo"
> attribute ref line 7 references an unknown ID "foo"
>
> I would like an example how to modify the above code to capture
> the error lines in some memory structure (chars array, ....).
>
> Is it possible?
>
> I suppose that it needs to write a function (like *printf functions)
> to call in place of fprintf (in the above example).
>
> Is there any example of code?
>
> Francesco
>
> I tried by changing fprintf with sprintf and stderr with (outerr) a  
> character
> string, but in this case I get
> - only one line of the above errors
> - I have the problem... how much length should be outerr chars array?

If you are using libxml in a C++ program, it looks like you can use  
the Boost Iostreams library to capture everything sent to std::cout or  
std::cerr in an ostream buffer. I have not done this myself, but a  
quick look at the library documentation made me think it was possible.  
The FAQ mentions a tee_filter. My guess is that you could tee the  
stderr streams into a buffer that you can examine. See http://www.boost.org/doc/libs/1_37_0/libs/iostreams/doc/index.html

Best regards,
Rush