[vlc-devel] [RFC] vlc_xml: add copy node function

[Rémi Denis-Courmont]

Le torstaina 23. helmikuuta 2017, 11.39.21 EET Nicolas Bertrand a écrit :
> Add a copy node function to the XML parser.
> Will be used to send in, XML format, parts of subs XML files from demux to
> codec.

Well, switching away from streaming model look nice from programming point of 
view. But it will cause problems unless you ensure that a given part data is 
reasonably small.

> The goal is to limit the use of libxml2 function in module/misc/xml/libxml.c
> 
> 
> ---
>  include/vlc_xml.h         |  7 +++++++
>  modules/misc/xml/libxml.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/include/vlc_xml.h b/include/vlc_xml.h
> index 661e76d..fd14ab6 100644
> --- a/include/vlc_xml.h
> +++ b/include/vlc_xml.h
> @@ -75,6 +75,7 @@ struct xml_reader_t
> 
>      int (*pf_use_dtd) ( xml_reader_t * );
>      int (*pf_is_empty) ( xml_reader_t * );
> +    int (*pf_copy_node) ( xml_reader_t *, const char **);

If there is only one error case (or no need to distinguish errors), then you 
are better off returning a char * directly.

And something looks fishy here. How can the result be constant? What´s the 
life cycle?

>  };
> 
>  VLC_API xml_reader_t * xml_ReaderCreate(vlc_object_t *, stream_t *)
> VLC_USED; @@ -106,6 +107,12 @@ static inline int xml_ReaderIsEmptyElement(
> xml_reader_t *reader ) return reader->pf_is_empty( reader );
>  }
> 
> +static inline int xml_ReaderCopyNode( xml_reader_t *reader,
> +        const char ** psz_text)
> +{
> +    return reader->pf_copy_node( reader, psz_text);
> +}
> +
>  enum {
>      XML_READER_ERROR=-1,
>      XML_READER_NONE=0,
> diff --git a/modules/misc/xml/libxml.c b/modules/misc/xml/libxml.c
> index 059c269..5487ab4 100644
> --- a/modules/misc/xml/libxml.c
> +++ b/modules/misc/xml/libxml.c
> @@ -34,6 +34,7 @@
> 
>  #include <libxml/xmlreader.h>
>  #include <libxml/catalog.h>
> +#include <libxml/parser.h>
> 
>  /**************************************************************************
> *** * Module descriptor
> @@ -65,6 +66,7 @@ static const char *ReaderNextAttr( xml_reader_t *, const
> char ** ); static int ReaderIsEmptyElement( xml_reader_t *);
> 
>  static int ReaderUseDTD ( xml_reader_t * );
> +static int ReaderCopyNode( xml_reader_t *, const char ** );
> 
>  static void CatalogLoad( xml_t *, const char * );
>  static void CatalogAdd( xml_t *, const char *, const char *, const char *
> ); @@ -178,6 +180,7 @@ static int ReaderOpen( vlc_object_t *p_this )
>      p_reader->pf_next_attr = ReaderNextAttr;
>      p_reader->pf_is_empty = ReaderIsEmptyElement;
>      p_reader->pf_use_dtd = ReaderUseDTD;
> +    p_reader->pf_copy_node = ReaderCopyNode;
> 
>      return VLC_SUCCESS;
>  }
> @@ -294,3 +297,40 @@ static int ReaderIsEmptyElement( xml_reader_t *p_reader
> ) {
>      return xmlTextReaderIsEmptyElement( p_reader->p_sys->xml );
>  }
> +
> +static int ReaderCopyNode(xml_reader_t *p_reader, const char **psz_text)
> +{
> +    xmlDocPtr doc;
> +    xmlNode *p_cur_node = NULL;
> +    xmlNode *p_copy_node = NULL;
> +    xmlNode *p_root_node = NULL;
> +    xmlChar *xmlbuff;
> +    int xmlbuffsize;
> +    const char *p_text;
> +
> +    xmlTextReaderPtr xml = p_reader->p_sys->xml;
> +
> +    p_cur_node = xmlTextReaderExpand(xml);
> +    if (!p_cur_node)
> +        return VLC_EGENERIC;
> +
> +    p_copy_node = xmlCopyNode(p_cur_node,1);
> +    if (!p_copy_node)
> +        return VLC_EGENERIC;
> +
> +    /* create new XML doc */
> +    doc = xmlNewDoc(BAD_CAST "1.0");
> +    p_root_node = xmlDocSetRootElement(doc, p_copy_node);
> +    if (p_root_node)
> +        /* No previous root node */
> +        return VLC_EGENERIC;
> +
> +    xmlDocDumpFormatMemoryEnc(doc, &xmlbuff, &xmlbuffsize, "UTF-8", 0);
> +
> +    if( psz_text != NULL )
> +        *psz_text =  strdup( (char *) xmlbuff);
> +
> +    xmlFree(xmlbuff);
> +    xmlFreeDoc(doc);
> +    return VLC_SUCCESS;
> +}


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