解析XML文件并写入链接列表

Question

I am trying to parse XML data and save it in a linked list which is supposed to be loaded in the main memory on boot. When the XML data is parsed, I want a set of XML entity/elements to be written in one Node of the linked list and the next set of data in the next node. While trying to achieve this, I am able to parse the data that I need but the assigning of the data to the linked list isn't happening as the logic I am trying to apply seems incorrect. I would like some help on the same.

File.xml

<policyList>
        <policySecurity>
                <policyName>AutoAdd</policyName>
                <deviceName>PA-722</deviceName>
                <status>ACTIVE</status>
                <srcZone>any</srcZone>
                <dstZone>any</dstZone>
                <srcAddr>any</srcAddr>
                <dstAddr>5.5.5.4</dstAddr>
                <srcUser>any</srcUser>
                <application>any</application>
                <service>any</service>
                <urlCategory>any</urlCategory>
                <action>deny</action>
        </policySecurity>
        <policySecurity>
                <policyName>Test-1</policyName>
                <deviceName>PA-710</deviceName>
                <status>ACTIVE</status>
                <srcZone>any</srcZone>
                <dstZone>any</dstZone>
                <srcAddr>192.168.1.23</srcAddr>
                <dstAddr>8.8.8.8</dstAddr>
                <srcUser>vivek</srcUser>
                <application>any</application>
                <service>any</service>
                <urlCategory>any</urlCategory>
                <action>deny</action>
        </policySecurity>
</policyList>

File.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <libxml/parser.h>


struct node {
        char *polname;
        char *devname;
        char *status;
        char *srczone;
        char *dstzone;
        char *srcaddr;
        char *dstaddr;
        char *srcuser;
        char *app;
        char *service;
        char *urlcategory;
        char *action;
        char *vulnerability;


        struct node *next;
            };
        struct node *head;

void insert(char *a, char *b, char *c, char *d, char *e, char *f, char*g, char *h, char *i, char *j, char *k, char *l, char *m){
        struct node *temp;
        temp = (struct node*)malloc(sizeof(struct node));
        temp->polname = a;
        temp->devname = b;
        temp->status = c;
        temp->srczone = d;
        temp->dstzone = e;
        temp->srcaddr = f;
        temp->dstaddr = g;
        temp->srcuser = h;
        temp->app = i;
        temp->service = j;
        temp->urlcategory = k;
        temp->action = l;
        temp->next = head;
        head= temp;
}
/* This is where the error occurs */
void traverse_dom_trees(xmlNode * a_node)
{
    xmlNode *cur_node = NULL;

    for (cur_node = a_node; cur_node; cur_node = cur_node->next)
    {
        if (cur_node->type == XML_ELEMENT_NODE)
        {
              /*  char *a,*b,*c,*d,*e,*f,*g,*h,*i,*j,*k,*l,*m; */
                 if(strcmp((const char *)cur_node->name,(const char *)"policyName") == 0){
                    printf("entered second if");
                    cur_node = cur_node->next;
                    printf("cur_node->next");
                    a = (char *)cur_node->content;
                    printf("value of a is %d", *a);
                    /*strcpy(*a,(const char *)cur_node->content);
                    printf("strcpy");
                    break;*/
               /*     }
             else if(strcmp((const char *)cur_node->name,(const char *)"deviceName") == 0)  {
                     cur_node = cur_node->next;
                    strcpy(*b,(const char *)cur_node->content);
                    break;
                    }
            else if(strcmp((const char *)cur_node->name,(const char *)"status") == 0){
                     cur_node = cur_node->next;
                    strcpy(*c,(const char *)cur_node->content);
                    break;
                    }
            else if(strcmp((const char *)cur_node->name,(const char *)"srcZone") == 0){
                     cur_node = cur_node->next;
                    strcpy(*d,(const char *)cur_node->content);
                    break;
                    }
            else if(strcmp((const char *)cur_node->name,(const char *)"dstZone") == 0){
                     cur_node = cur_node->next;
                    strcpy(*e,(const char *)cur_node->content);
                    break;
                    }
            else if(strcmp((const

 char *)cur_node->name,(const char *)"srcAddr") == 0){
                         cur_node = cur_node->next;
                        strcpy(*f,(const char *)cur_node->content);
                        break;
                        }
                else if(strcmp((const char *)cur_node->name,(const char *)"dstAddr") == 0){
                         cur_node = cur_node->next;
                        strcpy(*g,(const char *)cur_node->content);
                        break;
   }
                else if(strcmp((const char *)cur_node->name,(const char *)"srcUser") == 0){
                         cur_node = cur_node->next;
                         strcpy(*h,(const char *)cur_node->content);
                        break;
                        }
                else if(strcmp((const char *)cur_node->name,(const char *)"application") == 0){
                         cur_node = cur_node->next;
                         strcpy(*i,(const char *)cur_node->content);
                        break;
                        }
                else if(strcmp((const char *)cur_node->name,(const char *)"service") == 0){
                         cur_node = cur_node->next;
                         strcpy(*j,(const char *)cur_node->content);
                        break;
                        }
                else if(strcmp((const char *)cur_node->name,(const char *)"urlCategory") == 0){
                         cur_node = cur_node->next;
                         strcpy(*k,(const char *)cur_node->content);
                        break;
                        }
                else if(strcmp((const char *)cur_node->name,(const char *)"action") == 0){
                         cur_node = cur_node->next;
                         strcpy(*l,(const char *)cur_node->content);
                        break;
                        }
                else if(strcmp((const char *)cur_node->name,(const char *)"vulnerability") == 0){
                         cur_node = cur_node->next;
                         strcpy(*m,(const char *)cur_node->content);
                        break;
                        }*/

          /*insert( a, b, c, d, e, f, g, h, i, j, k, l, m);*/
    }

        traverse_dom_trees(cur_node->children);
    }
}

int main(int argc, char **argv)
{
    xmlDocPtr doc;
    xmlNode *roo_element = NULL;

    if (argc != 2)
    {
        printf("\nInvalid argument\n");
        return(1);
    }

    doc = xmlReadFile(argv[1], NULL, XML_PARSE_NOBLANKS | XML_PARSE_NOERROR | XML_PARSE_NOWARNING | XML_PARSE_NONET);
    if (doc == NULL)
    {
        fprintf(stderr, "Document not parsed successfully.\n");
        return 0;
    }

    roo_element = xmlDocGetRootElement(doc);

    if (roo_element == NULL)
 {
        fprintf(stderr, "empty document\n");
        xmlFreeDoc(doc);
        return 0;
    }

    printf("Root Node is %s\n", roo_element->name);
    traverse_dom_trees(roo_element);

    xmlFreeDoc(doc);       // free document
    xmlCleanupParser();    // Free globals
    return 0;
}

As you can see, I am trying a if/else if statement to assign the respective values to the node in linked list and it prints the following:

Root Node is policyList
Segmentation fault

Am I applying a wrong logic to implement what I have to do? Should I take a different approach for the same?

Please bear with the code, as it does seem long at various places(and I am still in my learning phase). Any and all help/suggestions will be appreciated. Thanks in advance :)

Edit 1: I switched to if/else rather than switch/case . Moreover, most of the warnings that were being shown before are mainly because of wrong assignment. I have commented most of the bugsy code to know what part of my code is working and what needs to be corrected. While debugging, I realized that it's the assignment part which is not working, because I think I'm not using the right way to save the data present in the pointer memory to the corresponding variable/pointer variable. Since it is printing the root node for me and also the printf till second if is called, so I assume that the rest of the code is correct, just the pointer assignment isn't working as it is supposed to.

Answer 1

The content is not contained in the XML_ELEMENT_NODE , but in a child node of type XML_TEXT_NODE (see Retrieving Element Content ), so we'd have to change

                    a = (char *)cur_node->content;

to

                    a = (char *)cur_node->xmlChildrenNode->content;

or

                    a = (char *)xmlNodeListGetString(cur_node->doc, cur_node->xmlChildrenNode, 0);

The latter returns a copy of the string, which can be freed with xmlFree() .