Re: [xml] xmlGcMemSetup & xmlMemSetup

[Marco Spinetti <spinmar interfree it>]

Ok,
I delete may errors and now I am getting an error using libxslt.
If I parse a doc and dump it there is no problem, but if I try to apply 
a stylesheet I get a segmentation fault.
If you compile the code with -DDUMP there is no problem, while if you 
don't put it you get a segmentation.
This is the code:

#include <libxml/parser.h>
#include <libxml/xmlmemory.h>
#include <libxml/encoding.h>

#include <libxslt/xslt.h>
#include <libxslt/xsltInternals.h>
#include <libxslt/transform.h>
#include <libxslt/xsltutils.h>

#include <stdlib.h>

const unsigned int mgc = 0x88DEFEA7;

static void *xml2_alloc(size_t sz)
{
   const unsigned int *ss;
   const unsigned int *mark;
   void *mem = malloc(sz + 2 * sizeof(int));
  
   if (mem == NULL)
       return NULL;
      
   ss = mem;
   mark = mem + sizeof(int);
   *ss = sz;
   *mark = mgc;
   return (char *) mem + 2 * sizeof(int);
}
  
void xml2_free(void *emem)
{
   void *mem;
   const unsigned int *mark;
  
   if (emem == NULL)
       return;
      
   mem = (char *)emem - 2 * sizeof(int);
   mark = mem + sizeof(int);
   if (*mark == mgc) {
       free(mem);
   }
}

static void *xml2_realloc(void * emem, size_t sz)
{
   void *mem;
   const unsigned int *s;
   void *mem_re;
  
   if (emem == NULL)
       return xml2_alloc(sz);
   else if (sz == 0)
       xml2_free(emem);
  
   mem = (char *)emem - 2 * sizeof(int);
   s = mem;
   mem_re = xml2_alloc(sz);
  
   memcpy(mem_re, emem, *s);
  
   xml2_free(emem);
  
   return mem_re;
}

static char *xml2_strdup(const char * str)
{
   char *s = xml2_alloc(strlen(str) + 1);
   if (s == NULL)
       return NULL;
  
   strcpy(s, str);
  
   return s;
}

xmlDocPtr
parseDoc(char *xmlfile)
{
   xmlDocPtr doc;
   xmlNodePtr root;

   doc = xmlParseFile(xmlfile);

   if (doc == NULL ) {
       fprintf(stderr,"Document not parsed successfully. \n");
       xmlFreeDoc(doc);
       return (NULL);
   }

   root = xmlDocGetRootElement(doc);

   if (root == NULL) {
       fprintf(stderr,"empty document\n");
       xmlFreeDoc(doc);
       return (NULL);
   }

   return doc;

}

int
main(int argc, char **argv) {
   xmlDocPtr doc;
   xsltStylesheetPtr cur = NULL;
   xmlDocPtr res;

   xmlChar *bufptr;
   int size = 0;
   char *xmlfile = "prova.xml";
   char * xslfilename    = "xxx.xsl";
  
   xmlMemSetup(xml2_free, xml2_alloc, xml2_realloc, xml2_strdup);
   xmlInitParser();
  
   doc = parseDoc (xmlfile);
  
   if (doc == NULL) {
       fprintf(stderr,"[ERRORE] ParseDoc ha ritornato NULL\n");
       return -1;
   }
  
   #ifdef DUMP
   xmlDocDumpMemoryEnc(doc, &bufptr, &size, "UTF-8");
     fprintf(stderr, "Out = %s\n", bufptr);
     xmlFreeDoc(doc);
     xmlFree(bufptr);
     xmlCleanupParser();
     return 1;
   #endif
  
   xmlSubstituteEntitiesDefault(1);

   exsltRegisterAll();
  
   cur = xsltParseStylesheetFile((const xmlChar *)xslfilename);
  
   res = xsltApplyStylesheet(cur, doc, NULL);
  
   if (xsltSaveResultToString(&bufptr, &size, res, cur) == -1) {
       fprintf(stderr, "Errore nella funzione xsltSaveResultToString\n");
       xmlFree(bufptr);
       xsltFreeStylesheet(cur);
       xmlFreeDoc(res);

       xmlFreeDoc(doc);

       xsltCleanupGlobals();
       xmlCleanupParser();

       return -1;
   }
  
   fprintf(stderr, "Out = %s\n", bufptr);
  
   xmlFree(bufptr);

   xsltFreeStylesheet(cur);
   xmlFreeDoc(res);

   xmlFreeDoc(doc);
  
   return 0;
}

Is tehre some problems if you use xmlMemSetup and libxslt?
Best regards

Marco


William M. Brack ha scritto:
> Your two errors are caused because you are attempting to use the xml2
> library functions xmlMemRealloc and xmlMemoryStrdup within your
> "personal" routines.  This kind of "mixing" may not be done.  Within your
> function "xml2_realloc" you should only call upon realloc, and you should
> provide "your own" version of strdup (probably calling xml2_alloc and
> memcpy).
>
> Bill
>
> Marco Spinetti wrote:
>   
> > I tried to use xmlMemSetup and libxml2 gives me an error.
> > Probably I'm missing something.
> > This is a simple main I wrote:
> >
> > #include <libxml/parser.h>
> > #include <libxml/xmlmemory.h>
> > #include <libxml/encoding.h>
> > #include <stdlib.h>
> >
> > const unsigned int mgc = 0x88DEFEA7;
> >
> > static void *xml2_alloc(size_t sz)
> > {
> >    void *mem = malloc(sz + sizeof(int));
> >    const unsigned int *mark = mem;
> >    *mark = mgc;
> >    return (char *) mem + sizeof(int);
> > }
> >   static void xml2_free(void *emem)
> > {
> >    void *mem = (char *)emem - sizeof(int);
> >    const unsigned int *mark = mem;
> >    if (*mark == mgc) {
> >        free(mem);
> >    }
> > }
> >
> > static void *xml2_realloc(void * emem, size_t sz)
> > {
> >    void *mem = (char *)emem - sizeof(int);
> >    void *mem_re = xmlMemRealloc(mem, sz);
> >    if (mem_re != NULL)
> >        return (char *) mem_re + sizeof(int);
> >    else
> >        return NULL;
> > }
> >
> > xmlDocPtr
> > parseDoc(char *xmlfile)
> > {
> >    xmlDocPtr doc;
> >    xmlNodePtr root;
> >
> >    doc = xmlParseFile(xmlfile);
> >
> >    if (doc == NULL ) {
> >        fprintf(stderr,"Document not parsed successfully. \n");
> >        xmlFreeDoc(doc);
> >        return (NULL);
> >    }
> >
> >    root = xmlDocGetRootElement(doc);
> >
> >    if (root == NULL) {
> >        fprintf(stderr,"empty document\n");
> >        xmlFreeDoc(doc);
> >        return (NULL);
> >    }
> >
> >    return doc;
> >
> > }
> >
> > int
> > main(int argc, char **argv) {
> >    xmlDocPtr doc;
> >    xmlChar *bufptr;
> >    int size = 0;
> >    char *xmlfile = "/usr/local/apache/conf/conf_prova.xml";
> >      xmlMemSetup(xml2_free, xml2_alloc, xml2_realloc, xmlMemoryStrdup);
> >    xmlInitParser();
> >      doc = parseDoc (xmlfile);
> >      if (doc == NULL) {
> >        fprintf(stderr,"[ERRORE] ParseDoc ha ritornato NULL\n");
> >        return -1;
> >    }
> >      fprintf(stderr,"[OK] ParseDoc Ok\n");
> >      xmlFreeDoc(doc);
> >    xmlCleanupParser();
> >
> >    return 0;
> > }
> >
> > The xml document is very simple:
> >
> > <?xml version="1.0" encoding="ISO-8859-1"?>
> > <CONFIGURAZIONE>
> >        <Q>3</Q>
> >        <S>
> >                <H>e</H>
> >                <P>80</P>
> >                <L>p.l</L>
> >                <PAR>
> >                        <AD>on</AD>
> >                        <S>off</S>
> >                        <C>r</C>
> >                        <N>0</N>
> >                        <W>1</W>
> >                </PAR>
> >        </S>
> >        .....
> > </CONFIGURAZIONE>
> >
> > this is the error I get:
> >
> >
> > [site sms-lt01 test]$ ./main
> > xmlMallocBreakpoint reached on block 0
> > Memory tag error occurs :0x805c140
> >         bye
> > Memory tag error occurs :0x805c158
> >         bye
> > /usr/local/apache/conf/conf_prova.xml:1: parser error : Memory
> > allocation failed
> > <?xml version="1.0" encoding="ISO-8859-1"?>
> >                                       ^
> > Document not parsed successfully.
> > [ERRORE] ParseDoc ha ritornato NULL
> >
> > What am I missing?
> >
> > Marco
> >
> >
> >
> > Daniel Veillard ha scritto:
> >     
> > > On Tue, Aug 07, 2007 at 12:09:05PM +0200, Marco Spinetti wrote:
> > >
> > >       
> > > > Reading the docs, I don't understand the difference between
> > > > xmlMemSetup
> > > > and xmlGcMemSetup.
> > > > I need to overwrite libxml2 memory allocation and I don't understand
> > > > if
> > > > I have to use xmlGcMemSetup or xmlMemSetup.
> > > > Any hints?
> > > >
> > > >         
> > >   http://xmlsoft.org/html/libxml-xmlmemory.html#xmlGcMemSetup
> > > the later has an extra function allowing a special function for
> > > allocation of atomic area (i.e. areas which will never be grown).
> > > In doubt use xmlMemSetup()
> > >
> > >
> > >       
> > > > Other question: is xmlInitMemory(9 should be called before use
> > > > xmlGcMemSetup or xmlMemSetup?
> > > >
> > > >         
> > >   no, xmlMemSetup must be the very first call to libxml2 then call
> > > xmlInitParser(). Don't call xmlInitMemory by yourself, xmlInitParser
> > > will do it.
> > >
> > > Daniel
> > >
> > >
> > >       
> > _______________________________________________
> > xml mailing list, project page  http://xmlsoft.org/
> > xml gnome org
> > http://mail.gnome.org/mailman/listinfo/xml
> >
> >     
>
>
>
>
>