libxmlplusplus-general

[libxml++] memory leak in SaxParser

[thierry <thi...@di...>]

I have encountered a memory leak (not signalized by Purify) in the class =
SaxParser.
in the function parse() :

"_context->sax =3D & _sax_handler;

[..]

release_underlying();"

is not valid. structure allocated in xmlCreateMemoryParserCtxt for the =
sax handler is never released due to=20

"_context->sax =3D 0 " in release_underlying().

The solution I have found was to use memcpy and to really release sax =
object of context.

I don't how to make patch so this is how looks my corrections in parse

void SaxParser::parse(){

if(!_context) throw internal_error("Parse context not created.");

//_context->sax =3D & _sax_handler;

memcpy(_context->sax, &_sax_handler, sizeof(xmlSAXHandler));

_context->userData =3D this;

initialize_context();


xmlParseDocument(_context);

if( (! _context->wellFormed)

&& (! _exception) )

_exception =3D new parse_error("Document not well-formed");

//release_underlying();

xmlFreeParserCtxt(_context);

_context =3D 0;

check_for_exception();

}

best regards

Thierry Blanchard

Re: [libxml++] memory leak in SaxParser

[Christophe de V. <cde...@al...>]

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Le Mercredi 23 Avril 2003 18:04, thierry a =E9crit :
> I have encountered a memory leak (not signalized by Purify) in the class
> SaxParser. in the function parse() :
>
> "_context->sax =3D & _sax_handler;
>
> [..]
>
> release_underlying();"
>
> is not valid. structure allocated in xmlCreateMemoryParserCtxt for the sax
> handler is never released due to
>
> "_context->sax =3D 0 " in release_underlying().
>


Thanks for reporting this problem.

In fact the good solution is probably to use xmlSAXUserParseFile and=20
xmlSAXUserParseMemory to create the contexts, and not=20
xmlCreateMemoryParserCtxt and xmlCreateFileParserCtxt which are to be used=
=20
only for DOM.

I'll commit a patch by the evening.


Best regards,

Christophe
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Re: [libxml++] memory leak in SaxParser

[Christophe de V. <cde...@al...>]

Le Mercredi 23 Avril 2003 19:03, Christophe de VIENNE a =E9crit :
> In fact the good solution is probably to use xmlSAXUserParseFile and
> xmlSAXUserParseMemory to create the contexts, and not
> xmlCreateMemoryParserCtxt and xmlCreateFileParserCtxt which are to be used
> only for DOM.

It seems I've spoken a bit fast sorry ;-) We can't do that. The functions I=
=20
spoke about don't return a context.

So we have to make sure either the sax handler can be freed by libxml, eith=
er=20
handle it ourselves.
The proposed solution was not handling the same problem happening with=20
xmlCreatePushParserCtxt, that we use for parse_chunk and parse_stream, whic=
h=20
makes a copy of the sax handle we give to it, and this copy is never=20
released.
So I removed the reset of sax handler in release_underlying. In parse, I ju=
st=20
save the defaut sax parser and restore after parsing, as it is done in=20
xmlCreateMemoryParserCtxt for example.

I think this correct the problem(s).

Cheers,

Christophe

Re: [libxml++] memory leak in SaxParser

[thierry <thi...@di...>]

at it is done in xmlSAXUserParseMemory...

I think this is the best solution.
Thank you for your immediate reaction.
Good luck


Thierry


----- Original Message -----
From: "Christophe de Vienne" <cde...@al...>
To: <lib...@li...>
Sent: Thursday, April 24, 2003 1:13 AM
Subject: Re: [libxml++] memory leak in SaxParser


Le Mercredi 23 Avril 2003 19:03, Christophe de VIENNE a écrit :
> In fact the good solution is probably to use xmlSAXUserParseFile and
> xmlSAXUserParseMemory to create the contexts, and not
> xmlCreateMemoryParserCtxt and xmlCreateFileParserCtxt which are to be used
> only for DOM.

It seems I've spoken a bit fast sorry ;-) We can't do that. The functions I
spoke about don't return a context.

So we have to make sure either the sax handler can be freed by libxml,
either
handle it ourselves.
The proposed solution was not handling the same problem happening with
xmlCreatePushParserCtxt, that we use for parse_chunk and parse_stream, which
makes a copy of the sax handle we give to it, and this copy is never
released.
So I removed the reset of sax handler in release_underlying. In parse, I
just
save the defaut sax parser and restore after parsing, as it is done in
xmlCreateMemoryParserCtxt for example.

I think this correct the problem(s).

Cheers,

Christophe



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Re: [libxml++] memory leak in SaxParser

[Christophe de V. <cde...@al...>]

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Le Jeudi 24 Avril 2003 09:56, thierry a =E9crit :
> as it is done in xmlSAXUserParseMemory...

yes.
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