ne_xml.c

linux subdivision ying gai ke yi le ba

/* 
   Higher Level Interface to XML Parsers.
   Copyright (C) 1999-2004, Joe Orton <[e-mail]>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA

*/

#include "config.h"

#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif

#include "ne_i18n.h"

#include "ne_alloc.h"
#include "ne_xml.h"
#include "ne_utils.h"
#include "ne_string.h"

#if defined(HAVE_EXPAT)
/* expat support: */
#ifdef HAVE_XMLPARSE_H
#include "xmlparse.h"
#else
#include <expat.h>
#endif
typedef XML_Char ne_xml_char;
#elif defined(HAVE_LIBXML)
/* libxml2 support: */
#include <libxml/xmlversion.h>
#include <libxml/parser.h>
typedef xmlChar ne_xml_char;

#else /* not HAVE_LIBXML */
#  error need an XML parser
#endif /* not HAVE_EXPAT */

/* Approx. one screen of text: */
#define ERR_SIZE (2048)

struct handler {
    ne_xml_startelm_cb *startelm_cb; /* start-element callback */
    ne_xml_endelm_cb *endelm_cb; /* end-element callback */
    ne_xml_cdata_cb *cdata_cb; /* character-data callback. */
    void *userdata; /* userdata for the above. */
    struct handler *next; /* next handler in stack. */
};

#ifdef HAVE_LIBXML
static void sax_error(void *ctx, const char *msg, ...);
#endif

struct element {
    const ne_xml_char *nspace;
    ne_xml_char *name;

    int state; /* opaque state integer */
    
    /* Namespaces declared in this element */
    ne_xml_char *default_ns; /* A default namespace */
    struct namespace *nspaces; /* List of other namespace scopes */

    struct handler *handler; /* Handler for this element */

    struct element *parent; /* parent element, or NULL */    
};

/* We pass around a ne_xml_parser as the userdata in the parsing
 * library.  This maintains the current state of the parse and various
 * other bits and bobs. Within the parse, we store the current branch
 * of the tree, i.e., the current element and all its parents, up to
 * the root, but nothing other than that.  */
struct ne_xml_parser_s {
    struct element *root; /* the root of the document */
    struct element *current; /* current element in the branch */
    struct handler *top_handlers; /* always points at the 
					   * handler on top of the stack. */
    int valid; /* non-zero whilst parse should continue */
    int prune; /* if non-zero, depth within a dead branch */

#ifdef HAVE_EXPAT
    XML_Parser parser;
    char *encoding;
#else
    xmlParserCtxtPtr parser;
#endif
    char error[ERR_SIZE];
};

/* The callback handlers */
static void start_element(void *userdata, const ne_xml_char *name, const ne_xml_char **atts);
static void end_element(void *userdata, const ne_xml_char *name);
static void char_data(void *userdata, const ne_xml_char *cdata, int len);
static const char *resolve_nspace(const struct element *elm, 
                                  const char *prefix, size_t pfxlen);

/* Linked list of namespace scopes */
struct namespace {
    ne_xml_char *name;
    ne_xml_char *uri;
    struct namespace *next;
};

#ifdef HAVE_LIBXML

/* Could be const as far as we care, but libxml doesn't want that */
static xmlSAXHandler sax_handler = {
    NULL, /* internalSubset */
    NULL, /* isStandalone */
    NULL, /* hasInternalSubset */
    NULL, /* hasExternalSubset */
    NULL, /* resolveEntity */
    NULL, /* getEntity */
    NULL, /* entityDecl */
    NULL, /* notationDecl */
    NULL, /* attributeDecl */
    NULL, /* elementDecl */
    NULL, /* unparsedEntityDecl */
    NULL, /* setDocumentLocator */
    NULL, /* startDocument */
    NULL, /* endDocument */
    start_element, /* startElement */
    end_element, /* endElement */
    NULL, /* reference */
    char_data, /* characters */
    NULL, /* ignorableWhitespace */
    NULL, /* processingInstruction */
    NULL, /* comment */
    NULL, /* xmlParserWarning */
    sax_error, /* xmlParserError */
    sax_error, /* fatal error (never called by libxml2?) */
    NULL, /* getParameterEntity */
    char_data /* cdataBlock */
};

/* empty attributes array to mimic expat behaviour */
static const char *empty_atts[] = {NULL, NULL};

/* macro for determining the attributes array to pass */
#define PASS_ATTS(atts) (atts ? (const char **)(atts) : empty_atts)

#else

#define PASS_ATTS(atts) ((const char **)(atts))

/* XML declaration callback for expat. */
static void decl_handler(void *userdata,
			 const XML_Char *version, const XML_Char *encoding, 
			 int standalone)
{
    ne_xml_parser *p = userdata;
    if (encoding) p->encoding = ne_strdup(encoding);    
}

#endif /* HAVE_LIBXML */

int ne_xml_currentline(ne_xml_parser *p) 
{
#ifdef HAVE_EXPAT
    return XML_GetCurrentLineNumber(p->parser);
#else
    return p->parser->input->line;
#endif
}

const char *ne_xml_doc_encoding(const ne_xml_parser *p)
{
#ifdef HAVE_LIBXML
    return p->parser->encoding;
#else
    return p->encoding;
#endif
}

/* Extract the namespace prefix declarations from 'atts'. */
static int declare_nspaces(ne_xml_parser *p, struct element *elm,
                           const ne_xml_char **atts)
{
    int n;
    
    for (n = 0; atts && atts[n]; n += 2) {
        if (strcasecmp(atts[n], "xmlns") == 0) {
            /* New default namespace */
            elm->default_ns = ne_strdup(atts[n+1]);
        } else if (strncasecmp(atts[n], "xmlns:", 6) == 0) {
            struct namespace *ns;
            
            if (atts[n][6] == '\0' || atts[n+1][0] == '\0') {
                ne_snprintf(p->error, ERR_SIZE, 
                            ("XML parse error at line %d: invalid namespace "
                             "declaration"), ne_xml_currentline(p));
                return -1;
            }

            /* New namespace scope */
            ns = ne_calloc(sizeof(*ns));
            ns->next = elm->nspaces;
            elm->nspaces = ns;
            ns->name = ne_strdup(atts[n]+6); /* skip the xmlns= */
            ns->uri = ne_strdup(atts[n+1]);
        }
    }
    
    return 0;
}

/* Expand an XML qualified name, which may include a namespace prefix
 * as well as the local part. */
static int expand_qname(ne_xml_parser *p, struct element *elm,
                        const ne_xml_char *qname)
{
    const ne_xml_char *pfx;

    pfx = strchr(qname, ':');
    if (pfx == NULL) {
        struct element *e = elm;

        /* Find default namespace; guaranteed to terminate as the root
         * element always has default_ns="". */
        while (e->default_ns == NULL)
            e = e->parent;
        
        elm->name = ne_strdup(qname);
        elm->nspace = e->default_ns;
    } else {
        const char *uri = resolve_nspace(elm, qname, pfx-qname);

	if (uri) {
	    /* The name is everything after the ':' */
	    if (pfx[1] == '\0') {
		ne_snprintf(p->error, ERR_SIZE, 
			    ("XML parse error at line %d: element name missing"
                             "after namespace prefix"), ne_xml_currentline(p));
		return -1;
	    }
	    elm->name = ne_strdup(pfx+1);
            elm->nspace = uri;
	} else {
	    ne_snprintf(p->error, ERR_SIZE, 
                        ("XML parse error at line %d: undeclared namespace"),
                        ne_xml_currentline(p));
	    return -1;
	}
    }
    return 0;
}

/* Called with the start of a new element. */
static void start_element(void *userdata, const ne_xml_char *name,
			  const ne_xml_char **atts) 
{
    ne_xml_parser *p = userdata;
    struct element *elm;
    struct handler *hand;
    int state = NE_XML_DECLINE;

    if (!p->valid) return;
    
    if (p->prune) {
        p->prune++;
        return;
    }

    /* Create a new element */
    elm = ne_calloc(sizeof *elm);
    elm->parent = p->current;
    p->current = elm;

    if (declare_nspaces(p, elm, atts) || expand_qname(p, elm, name)) {
        p->valid = 0;
        return;
    }

    /* Find a handler which will accept this element (or abort the parse) */
    for (hand = elm->parent->handler; hand && state == NE_XML_DECLINE;
         hand = hand->next) {
        elm->handler = hand;
        state = hand->startelm_cb(hand->userdata, elm->parent->state,
                                  elm->nspace, elm->name, PASS_ATTS(atts));
    }

    NE_DEBUG(NE_DBG_XMLPARSE, "XML: start-element (%d, {%s, %s}) => %d\n", 
             elm->parent->state, elm->nspace, elm->name, state);