如何获取xmlHashTable的键？ （libxml2的）

Question

我使用库libxml2来解析XML文档。然后我在这个库中看到了xmlHashTable。是否可以获得xmlHashTable的所有密钥？我想将所有键存储在一个数组中。

XML文档是：

<?xml version="1.0" encoding="UTF-8"?>

<?type-proto key="MIPRegistrationRequest" value="mip" ?>
<?avp-proto key="Example-AVP" value="data" ?>

<!DOCTYPE dictionary SYSTEM "dictionary.dtd" [
    <!-- Any files added here need to be added to Makefile.am and
         packaging/nsis/wireshark.nsi -->

    <!ENTITY nasreq         SYSTEM "nasreq.xml">
    <!ENTITY eap            SYSTEM "eap.xml">
    <!ENTITY mobileipv4     SYSTEM "mobileipv4.xml">
    <!ENTITY chargecontrol      SYSTEM "chargecontrol.xml">
    <!ENTITY sunping        SYSTEM "sunping.xml">
    <!ENTITY TGPP           SYSTEM "TGPP.xml">
    <!ENTITY TGPP2          SYSTEM "TGPP2.xml">
    <!ENTITY sip            SYSTEM "sip.xml">
    <!ENTITY etsie2e4       SYSTEM "etsie2e4.xml">
    <!ENTITY Ericsson       SYSTEM "Ericsson.xml">
    <!ENTITY mobileipv6     SYSTEM "mobileipv6.xml">
    <!ENTITY Cisco          SYSTEM "Cisco.xml">
    <!ENTITY Starent        SYSTEM "Starent.xml">
    <!ENTITY Vodafone       SYSTEM "Vodafone.xml">
    <!ENTITY AlcatelLucent      SYSTEM "AlcatelLucent.xml">
    <!ENTITY Nokia          SYSTEM "Nokia.xml">
    <!ENTITY NokiaSolutionsAndNetworks  SYSTEM "NokiaSolutionsAndNetworks.xml">
    <!ENTITY HP         SYSTEM "HP.xml">
    <!ENTITY Oracle         SYSTEM "Oracle.xml">
    <!ENTITY Custom         SYSTEM "Custom.xml">
]>
<dictionary>
...
<dictionary>

我试图获取外部（解析）实体的所有键（例如nasreq，eap等）：

ddict_t *ddict_scan(const char* system_directory, const char* filename) 
{

    char *path = g_strconcat((const gchar*) system_directory, (const gchar*)filename, (const gchar *)'\0');
    xmlDocPtr p1 = getdoc((const char *)path);
    xmlEntitiesTablePtr ptr2 = p1->intSubset->entities;
    //to be added
}

xmlEntitiesTable的类型是xmlHashTable。

Answer 1

有xmlHashScan()函数（及其pickier亲属），可用于为xmlHashTable中的每个条目库提供一个用户提供的xmlHashScanner函数。 。 xmlHashScanner被赋予每个条目的name作为参数，因此应该很容易汇总所有密钥的列表。

Answer 2

您的问题是典型的XY problem。获取实体声明的更简单方法是迭代DTD节点的子节点：

xmlDtdPtr dtd = doc->intSubset;

for (xmlNodePtr child = dtd->children; child; child = child->next) {
    if (child->type == XML_ENTITY_DECL) {
        printf("%s\n", child->name);
    }
}

Answer 3

对于那些想要了解更多详细信息（特别是代码）的人，您可以查看以下代码，以帮助我获取密钥列表：

typedef struct _entities_key_list{
    xmlChar *name;
    struct _entities_key_list *next;
} entities_key_list;

static entities_key_list *head_key_list = NULL;
static entities_key_list *current_key_list = NULL;

/**
 * @brief Callback when scanning data in a hash with the simple scanner
 * @param the data in the hash
 * @param extra scanner data
 * @param the name associated
 * @return void
 */
void the_callback_function(void *payload, void *data, xmlChar *name){
    if(!head_key_list)
    {
        head_key_list = current_key_list = g_new(entities_key_list, 1);
        head_key_list->name = name;
        head_key_list->next = NULL;
    }
    else
    {
        current_key_list = current_key_list->next = g_new(entities_key_list, 1);
        current_key_list->name = name;
        current_key_list->next = NULL;
    }
}

/**
 * @brief Parses the entity inforamtion in the XML document: dictionary.xml
 * @param ptr pointer to an XML document
 * @return pointer to a linked list of type entity_t
 */
entity_t *parse_entities(xmlDocPtr ptr) 
{
    xmlHashScanner ptr27 = &the_callback_function;
    xmlHashTablePtr ptr28 = (xmlHashTablePtr) ptr->intSubset->entities;
    xmlHashScan(ptr28, ptr27, NULL);
    puts("**************************************************");
    puts("let's test if I have got the great result!");
    printf("the result is: %s\n", head_key_list->name);
    printf("the result is: %s\n", head_key_list->next->name);
    puts("**************************************************");
... //code that is not interesting anymore
}