[C] Parsing and Validate XML file for dump all content contained on nodes. (see below about dependencies and exec)

rssxml_reader.c

/***
 * toolname: RSS.xml Reader
 * synopsis: Parsing and Validate all content contained on RSS.xml
 *           using libXML2
 * purpose: Show how use the function xmlReaderforFile() -, just
 *          for education coding
 * author: sl4y3r_0wn3r | slayer owner
 * compile: gcc -o <output> -Werror -Wall <source.c> $(xml2-config --libs --cflags) -Winline
 * preview: http://i.imgur.com/EleRdUI.png
 ***/

#include <stdio.h>
#include <stdlib.h>
#include <libxml/xmlreader.h>

#ifndef LIBXML_READER_ENABLED

static inline void /* the function not will be "inline" because GCC doesn't.
                    * unless 'always_inline' attribute is specified */
print_usage(const char *argv0) __attribute__((always_inline));

static void /* rss.xml handling */
streamXML(const char *filename); /* filename to parse */

static void
procNode(xmlTextReaderPtr reader);
int main(int argc, char *argv[])
{   
    int ReturnToExit = EXIT_SUCCESS;
    if (argc != 2){
        print_usage(argv[0]);
        goto b_ReturnToExit;
    }

    LIBXML_TEST_VERSION /* (Macro) for testing API */

    streamXML(argv[1]);

    xmlCleanupParser();
    xmlMemoryDump();

    return ReturnToExit; /* EXIT_SUCCESS; */

b_ReturnToExit:
    ReturnToExit = EXIT_FAILURE;
    return ReturnToExit;
}

#else
void main(void)
{
    fprintf(stderr,
        "XInclude support not compiled in\n");
    exit(EXIT_FAILURE);
}
#endif

static void
procNode(xmlTextReaderPtr reader)
{
    const xmlChar *value;
    value = xmlTextReaderConstValue(reader);

    do{
        if (value == NULL){ break; }
        if (xmlStrlen(value) > 0)
            printf(" %s", (char *)value);
    }while(0);
}

static void
streamXML(const char *filename)
{
    xmlTextReaderPtr    reader;
    int ret;    

    reader = xmlReaderForFile(filename,NULL, /* filename,encoding,int option */
//                              XML_PARSE_DTDATTR | /* DTD attr defaults */
//                              XML_PARSE_DTDVALID   | /* Valida with the DTD */
                              XML_PARSE_NOENT);/* No Entities */
    if (reader != NULL){
        ret = xmlTextReaderRead(reader);
        while (!(ret == 0)){
            procNode(reader);
            ret = xmlTextReaderRead(reader);
        }

        if (!!(xmlTextReaderIsValid(reader))){ /* edit !! for ! to enable xml validate */
            fprintf(stderr,
                "[!] Document %s does not validate\n", filename);
        }
        xmlFreeTextReader(reader);
        if (ret != 0){
            fprintf(stderr,
                "[!] %s: failed to parse\n", filename);
        }
    }else{
            fprintf(stderr,"[!] unable to open %s\n", filename);
    }
}

static inline void
print_usage(const char *argv0)
{
    fprintf(stderr,
        "[!] Usage: %s <rss.xml>\n",argv0);
}

installing LibXML2:

$ apt-get install libxml2 libxml2-dev libxslt1-dev 

compiling:

$ gcc -o <output> -Werror -Wall <source.c> $(xml2-config --libs --cflags)

execute:

root@slayer:~# ./rssxml_reader.c
[!] Usage: ./rssxml_reader.c <rss.xml>

Preview: http://i.imgur.com/EleRdUI.png

Dropping this as public 2 years later.
This is a simple PoC code when I was studying 'XML parsing' in C.

Note: Do not use LibXML in your project because it has so many lack of security, such as denial of service. I recommend "LibXMLSec".