Listing 7. The plugins return the metadata using a simple linked
list.

static void addKeyword
   (struct EXTRACTOR_Keywords ** list,
    char * keyword,
    EXTRACTOR_KeywordType type)
{
  EXTRACTOR_KeywordList * next;
  next = malloc(sizeof(EXTRACTOR_KeywordList));
  next->next = *list;
  next->keyword = keyword;
  next->keywordType = type;
  *list = next;
}