c14n.c

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/*
 * "Canonical XML" implementation
 * http://www.w3.org/TR/xml-c14n
 *
 * "Exclusive XML Canonicalization" implementation
 * http://www.w3.org/TR/xml-exc-c14n
 *
 * See Copyright for the status of this software.
 *
 * Author: Aleksey Sanin <aleksey@aleksey.com>
 */
#define IN_LIBXML
#include "libxml.h"
#ifdef LIBXML_C14N_ENABLED
#ifdef LIBXML_OUTPUT_ENABLED
 
#include <stdlib.h>
#include <string.h>
 
#include <libxml/tree.h>
#include <libxml/parser.h>
#include <libxml/uri.h>
#include <libxml/xmlerror.h>
#include <libxml/globals.h>
#include <libxml/xpathInternals.h>
#include <libxml/c14n.h>
 
#include "buf.h"
 
/************************************************************************
 *                                  *
 *      Some declaration better left private ATM        *
 *                                  *
 ************************************************************************/
 
typedef enum {
    XMLC14N_BEFORE_DOCUMENT_ELEMENT = 0,
    XMLC14N_INSIDE_DOCUMENT_ELEMENT = 1,
    XMLC14N_AFTER_DOCUMENT_ELEMENT = 2
} xmlC14NPosition;
 
typedef struct _xmlC14NVisibleNsStack {
    int nsCurEnd;           /* number of nodes in the set */
    int nsPrevStart;        /* the beginning of the stack for previous visible node */
    int nsPrevEnd;          /* the end of the stack for previous visible node */
    int nsMax;              /* size of the array as allocated */
    xmlNsPtr    *nsTab;     /* array of ns in no particular order */
    xmlNodePtr  *nodeTab;   /* array of nodes in no particular order */
} xmlC14NVisibleNsStack, *xmlC14NVisibleNsStackPtr;
 
typedef struct _xmlC14NCtx {
    /* input parameters */
    xmlDocPtr doc;
    xmlC14NIsVisibleCallback is_visible_callback;
    void* user_data;
    int with_comments;
    xmlOutputBufferPtr buf;
 
    /* position in the XML document */
    xmlC14NPosition pos;
    int parent_is_doc;
    xmlC14NVisibleNsStackPtr ns_rendered;
 
    /* C14N mode */
    xmlC14NMode mode;
 
    /* exclusive canonicalization */
    xmlChar **inclusive_ns_prefixes;
 
    /* error number */
    int error;
} xmlC14NCtx, *xmlC14NCtxPtr;
 
static xmlC14NVisibleNsStackPtr xmlC14NVisibleNsStackCreate (void);
static void     xmlC14NVisibleNsStackDestroy    (xmlC14NVisibleNsStackPtr cur);
static void     xmlC14NVisibleNsStackAdd        (xmlC14NVisibleNsStackPtr cur,
                                                 xmlNsPtr ns,
                                                 xmlNodePtr node);
static void         xmlC14NVisibleNsStackSave   (xmlC14NVisibleNsStackPtr cur,
                                 xmlC14NVisibleNsStackPtr state);
static void         xmlC14NVisibleNsStackRestore    (xmlC14NVisibleNsStackPtr cur,
                                 xmlC14NVisibleNsStackPtr state);
static void         xmlC14NVisibleNsStackShift  (xmlC14NVisibleNsStackPtr cur);
static int          xmlC14NVisibleNsStackFind   (xmlC14NVisibleNsStackPtr cur,
                                 xmlNsPtr ns);
static int          xmlExcC14NVisibleNsStackFind    (xmlC14NVisibleNsStackPtr cur,
                                 xmlNsPtr ns,
                                 xmlC14NCtxPtr ctx);
 
static int          xmlC14NIsNodeInNodeset      (void *user_data,
                                 xmlNodePtr node,
                                 xmlNodePtr parent);
 
 
 
static int xmlC14NProcessNode(xmlC14NCtxPtr ctx, xmlNodePtr cur);
static int xmlC14NProcessNodeList(xmlC14NCtxPtr ctx, xmlNodePtr cur);
typedef enum {
    XMLC14N_NORMALIZE_ATTR = 0,
    XMLC14N_NORMALIZE_COMMENT = 1,
    XMLC14N_NORMALIZE_PI = 2,
    XMLC14N_NORMALIZE_TEXT = 3
} xmlC14NNormalizationMode;
 
static xmlChar *xmlC11NNormalizeString(const xmlChar * input,
                                       xmlC14NNormalizationMode mode);
 
#define xmlC11NNormalizeAttr( a ) \
    xmlC11NNormalizeString((a), XMLC14N_NORMALIZE_ATTR)
#define xmlC11NNormalizeComment( a ) \
    xmlC11NNormalizeString((a), XMLC14N_NORMALIZE_COMMENT)
#define xmlC11NNormalizePI( a ) \
    xmlC11NNormalizeString((a), XMLC14N_NORMALIZE_PI)
#define xmlC11NNormalizeText( a ) \
    xmlC11NNormalizeString((a), XMLC14N_NORMALIZE_TEXT)
 
#define xmlC14NIsVisible( ctx, node, parent ) \
     (((ctx)->is_visible_callback != NULL) ? \
    (ctx)->is_visible_callback((ctx)->user_data, \
        (xmlNodePtr)(node), (xmlNodePtr)(parent)) : 1)
 
#define xmlC14NIsExclusive( ctx ) \
    ( (ctx)->mode == XML_C14N_EXCLUSIVE_1_0 )
 
/************************************************************************
 *                                  *
 *      Some factorized error routines              *
 *                                  *
 ************************************************************************/
 
static void
xmlC14NErrMemory(const char *extra)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_C14N,
            XML_ERR_NO_MEMORY, XML_ERR_ERROR, NULL, 0, extra,
            NULL, NULL, 0, 0,
            "Memory allocation failed : %s\n", extra);
}
 
static void
xmlC14NErrParam(const char *extra)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_C14N,
            XML_ERR_INTERNAL_ERROR, XML_ERR_ERROR, NULL, 0, extra,
            NULL, NULL, 0, 0,
            "Invalid parameter : %s\n", extra);
}
 
static void
xmlC14NErrInternal(const char *extra)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_C14N,
            XML_ERR_INTERNAL_ERROR, XML_ERR_ERROR, NULL, 0, extra,
            NULL, NULL, 0, 0,
            "Internal error : %s\n", extra);
}
 
static void
xmlC14NErrInvalidNode(const char *node_type, const char *extra)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_C14N,
            XML_C14N_INVALID_NODE, XML_ERR_ERROR, NULL, 0, extra,
            NULL, NULL, 0, 0,
            "Node %s is invalid here : %s\n", node_type, extra);
}
 
static void
xmlC14NErrUnknownNode(int node_type, const char *extra)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_C14N,
            XML_C14N_UNKNOW_NODE, XML_ERR_ERROR, NULL, 0, extra,
            NULL, NULL, 0, 0,
            "Unknown node type %d found : %s\n", node_type, extra);
}
 
static void
xmlC14NErrRelativeNamespace(const char *ns_uri)
{
    __xmlRaiseError(NULL, NULL, NULL, NULL, NULL, XML_FROM_C14N,
            XML_C14N_RELATIVE_NAMESPACE, XML_ERR_ERROR, NULL, 0, NULL,
            NULL, NULL, 0, 0,
            "Relative namespace UR is invalid here : %s\n", ns_uri);
}
 
 
 
static void
xmlC14NErr(xmlC14NCtxPtr ctxt, xmlNodePtr node, int error,
           const char * msg)
{
    if (ctxt != NULL)
        ctxt->error = error;
    __xmlRaiseError(NULL, NULL, NULL,
            ctxt, node, XML_FROM_C14N, error,
            XML_ERR_ERROR, NULL, 0,
            NULL, NULL, NULL, 0, 0, "%s", msg);
}
 
/************************************************************************
 *                                  *
 *      The implementation internals                *
 *                                  *
 ************************************************************************/
#define XML_NAMESPACES_DEFAULT      16
 
static int
xmlC14NIsNodeInNodeset(void *user_data, xmlNodePtr node, xmlNodePtr parent) {
    xmlNodeSetPtr nodes = (xmlNodeSetPtr) user_data;
    if((nodes != NULL) && (node != NULL)) {
    if(node->type != XML_NAMESPACE_DECL) {
        return(xmlXPathNodeSetContains(nodes, node));
    } else {
        xmlNs ns;
 
        memcpy(&ns, node, sizeof(ns));
 
        /* this is a libxml hack! check xpath.c for details */
        if((parent != NULL) && (parent->type == XML_ATTRIBUTE_NODE)) {
        ns.next = (xmlNsPtr)parent->parent;
        } else {
        ns.next = (xmlNsPtr)parent;
        }
 
        /*
         * If the input is an XPath node-set, then the node-set must explicitly
         * contain every node to be rendered to the canonical form.
         */
        return(xmlXPathNodeSetContains(nodes, (xmlNodePtr)&ns));
    }
    }
    return(1);
}
 
static xmlC14NVisibleNsStackPtr
xmlC14NVisibleNsStackCreate(void) {
    xmlC14NVisibleNsStackPtr ret;
 
    ret = (xmlC14NVisibleNsStackPtr) xmlMalloc(sizeof(xmlC14NVisibleNsStack));
    if (ret == NULL) {
        xmlC14NErrMemory("creating namespaces stack");
    return(NULL);
    }
    memset(ret, 0 , (size_t) sizeof(xmlC14NVisibleNsStack));
    return(ret);
}
 
static void
xmlC14NVisibleNsStackDestroy(xmlC14NVisibleNsStackPtr cur) {
    if(cur == NULL) {
        xmlC14NErrParam("destroying namespaces stack");
        return;
    }
    if(cur->nsTab != NULL) {
    memset(cur->nsTab, 0, cur->nsMax * sizeof(xmlNsPtr));
    xmlFree(cur->nsTab);
    }
    if(cur->nodeTab != NULL) {
    memset(cur->nodeTab, 0, cur->nsMax * sizeof(xmlNodePtr));
    xmlFree(cur->nodeTab);
    }
    memset(cur, 0, sizeof(xmlC14NVisibleNsStack));
    xmlFree(cur);
 
}
 
static void
xmlC14NVisibleNsStackAdd(xmlC14NVisibleNsStackPtr cur, xmlNsPtr ns, xmlNodePtr node) {
    if((cur == NULL) ||
       ((cur->nsTab == NULL) && (cur->nodeTab != NULL)) ||
       ((cur->nsTab != NULL) && (cur->nodeTab == NULL))) {
        xmlC14NErrParam("adding namespace to stack");
    return;
    }
 
    if ((cur->nsTab == NULL) && (cur->nodeTab == NULL)) {
        cur->nsTab = (xmlNsPtr*) xmlMalloc(XML_NAMESPACES_DEFAULT * sizeof(xmlNsPtr));
        cur->nodeTab = (xmlNodePtr*) xmlMalloc(XML_NAMESPACES_DEFAULT * sizeof(xmlNodePtr));
    if ((cur->nsTab == NULL) || (cur->nodeTab == NULL)) {
        xmlC14NErrMemory("adding node to stack");
        return;
    }
    memset(cur->nsTab, 0 , XML_NAMESPACES_DEFAULT * sizeof(xmlNsPtr));
    memset(cur->nodeTab, 0 , XML_NAMESPACES_DEFAULT * sizeof(xmlNodePtr));
        cur->nsMax = XML_NAMESPACES_DEFAULT;
    } else if(cur->nsMax == cur->nsCurEnd) {
    void *tmp;
    int tmpSize;
 
    tmpSize = 2 * cur->nsMax;
    tmp = xmlRealloc(cur->nsTab, tmpSize * sizeof(xmlNsPtr));
    if (tmp == NULL) {
        xmlC14NErrMemory("adding node to stack");
        return;
    }
    cur->nsTab = (xmlNsPtr*)tmp;
 
    tmp = xmlRealloc(cur->nodeTab, tmpSize * sizeof(xmlNodePtr));
    if (tmp == NULL) {
        xmlC14NErrMemory("adding node to stack");
        return;
    }
    cur->nodeTab = (xmlNodePtr*)tmp;
 
    cur->nsMax = tmpSize;
    }
    cur->nsTab[cur->nsCurEnd] = ns;
    cur->nodeTab[cur->nsCurEnd] = node;
 
    ++cur->nsCurEnd;
}
 
static void
xmlC14NVisibleNsStackSave(xmlC14NVisibleNsStackPtr cur, xmlC14NVisibleNsStackPtr state) {
    if((cur == NULL) || (state == NULL)) {
        xmlC14NErrParam("saving namespaces stack");
    return;
    }
 
    state->nsCurEnd = cur->nsCurEnd;
    state->nsPrevStart = cur->nsPrevStart;
    state->nsPrevEnd = cur->nsPrevEnd;
}
 
static void
xmlC14NVisibleNsStackRestore(xmlC14NVisibleNsStackPtr cur, xmlC14NVisibleNsStackPtr state) {
    if((cur == NULL) || (state == NULL)) {
        xmlC14NErrParam("restoring namespaces stack");
    return;
    }
    cur->nsCurEnd = state->nsCurEnd;
    cur->nsPrevStart = state->nsPrevStart;
    cur->nsPrevEnd = state->nsPrevEnd;
}
 
static void
xmlC14NVisibleNsStackShift(xmlC14NVisibleNsStackPtr cur) {
    if(cur == NULL) {
        xmlC14NErrParam("shifting namespaces stack");
    return;
    }
    cur->nsPrevStart = cur->nsPrevEnd;
    cur->nsPrevEnd = cur->nsCurEnd;
}
 
static int
xmlC14NStrEqual(const xmlChar *str1, const xmlChar *str2) {
    if (str1 == str2) return(1);
    if (str1 == NULL) return((*str2) == '\0');
    if (str2 == NULL) return((*str1) == '\0');
    do {
    if (*str1++ != *str2) return(0);
    } while (*str2++);
    return(1);
}
 
static int
xmlC14NVisibleNsStackFind(xmlC14NVisibleNsStackPtr cur, xmlNsPtr ns)
{
    int i;
    const xmlChar *prefix;
    const xmlChar *href;
    int has_empty_ns;
 
    if(cur == NULL) {
        xmlC14NErrParam("searching namespaces stack (c14n)");
        return (0);
    }
 
    /*
     * if the default namespace xmlns="" is not defined yet then
     * we do not want to print it out
     */
    prefix = ((ns == NULL) || (ns->prefix == NULL)) ? BAD_CAST "" : ns->prefix;
    href = ((ns == NULL) || (ns->href == NULL)) ? BAD_CAST "" : ns->href;
    has_empty_ns = (xmlC14NStrEqual(prefix, NULL) && xmlC14NStrEqual(href, NULL));
 
    if (cur->nsTab != NULL) {
    int start = (has_empty_ns) ? 0 : cur->nsPrevStart;
        for (i = cur->nsCurEnd - 1; i >= start; --i) {
            xmlNsPtr ns1 = cur->nsTab[i];
 
        if(xmlC14NStrEqual(prefix, (ns1 != NULL) ? ns1->prefix : NULL)) {
        return(xmlC14NStrEqual(href, (ns1 != NULL) ? ns1->href : NULL));
        }
        }
    }
    return(has_empty_ns);
}
 
static int
xmlExcC14NVisibleNsStackFind(xmlC14NVisibleNsStackPtr cur, xmlNsPtr ns, xmlC14NCtxPtr ctx) {
    int i;
    const xmlChar *prefix;
    const xmlChar *href;
    int has_empty_ns;
 
    if(cur == NULL) {
        xmlC14NErrParam("searching namespaces stack (exc c14n)");
        return (0);
    }
 
    /*
     * if the default namespace xmlns="" is not defined yet then
     * we do not want to print it out
     */
    prefix = ((ns == NULL) || (ns->prefix == NULL)) ? BAD_CAST "" : ns->prefix;
    href = ((ns == NULL) || (ns->href == NULL)) ? BAD_CAST "" : ns->href;
    has_empty_ns = (xmlC14NStrEqual(prefix, NULL) && xmlC14NStrEqual(href, NULL));
 
    if (cur->nsTab != NULL) {
    int start = 0;
        for (i = cur->nsCurEnd - 1; i >= start; --i) {
            xmlNsPtr ns1 = cur->nsTab[i];
 
        if(xmlC14NStrEqual(prefix, (ns1 != NULL) ? ns1->prefix : NULL)) {
        if(xmlC14NStrEqual(href, (ns1 != NULL) ? ns1->href : NULL)) {
            return(xmlC14NIsVisible(ctx, ns1, cur->nodeTab[i]));
        } else {
            return(0);
        }
        }
        }
    }
    return(has_empty_ns);
}
 
 
 
 
/* todo: make it a define? */
static int
xmlC14NIsXmlNs(xmlNsPtr ns)
{
    return ((ns != NULL) &&
            (xmlStrEqual(ns->prefix, BAD_CAST "xml")) &&
            (xmlStrEqual(ns->href, XML_XML_NAMESPACE)));
}
 
 
static int
xmlC14NNsCompare(const void *data1, const void *data2)
{
    const xmlNsPtr ns1 = (const xmlNsPtr) data1;
    const xmlNsPtr ns2 = (const xmlNsPtr) data2;
    if (ns1 == ns2)
        return (0);
    if (ns1 == NULL)
        return (-1);
    if (ns2 == NULL)
        return (1);
 
    return (xmlStrcmp(ns1->prefix, ns2->prefix));
}
 
 
static int
xmlC14NPrintNamespaces(const xmlNsPtr ns, xmlC14NCtxPtr ctx)
{
 
    if ((ns == NULL) || (ctx == NULL)) {
        xmlC14NErrParam("writing namespaces");
        return 0;
    }
 
    if (ns->prefix != NULL) {
        xmlOutputBufferWriteString(ctx->buf, " xmlns:");
        xmlOutputBufferWriteString(ctx->buf, (const char *) ns->prefix);
        xmlOutputBufferWriteString(ctx->buf, "=");
    } else {
        xmlOutputBufferWriteString(ctx->buf, " xmlns=");
    }
    if(ns->href != NULL) {
    xmlBufWriteQuotedString(ctx->buf->buffer, ns->href);
    } else {
        xmlOutputBufferWriteString(ctx->buf, "\"\"");
    }
    return (1);
}
 
static int
xmlC14NPrintNamespacesWalker(const void *ns, void *ctx) {
    return xmlC14NPrintNamespaces((const xmlNsPtr) ns, (xmlC14NCtxPtr) ctx);
}
 
static int
xmlC14NProcessNamespacesAxis(xmlC14NCtxPtr ctx, xmlNodePtr cur, int visible)
{
    xmlNodePtr n;
    xmlNsPtr ns, tmp;
    xmlListPtr list;
    int already_rendered;
    int has_empty_ns = 0;
 
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("processing namespaces axis (c14n)");
        return (-1);
    }
 
    /*
     * Create a sorted list to store element namespaces
     */
    list = xmlListCreate(NULL, xmlC14NNsCompare);
    if (list == NULL) {
        xmlC14NErrInternal("creating namespaces list (c14n)");
        return (-1);
    }
 
    /* check all namespaces */
    for(n = cur; n != NULL; n = n->parent) {
    for(ns = n->nsDef; ns != NULL; ns = ns->next) {
        tmp = xmlSearchNs(cur->doc, cur, ns->prefix);
 
        if((tmp == ns) && !xmlC14NIsXmlNs(ns) && xmlC14NIsVisible(ctx, ns, cur)) {
        already_rendered = xmlC14NVisibleNsStackFind(ctx->ns_rendered, ns);
        if(visible) {
        xmlC14NVisibleNsStackAdd(ctx->ns_rendered, ns, cur);
        }
        if(!already_rendered) {
            xmlListInsert(list, ns);
        }
        if(xmlStrlen(ns->prefix) == 0) {
            has_empty_ns = 1;
        }
        }
    }
    }
 
    if(visible && !has_empty_ns) {
        static xmlNs ns_default;
 
        memset(&ns_default, 0, sizeof(ns_default));
        if(!xmlC14NVisibleNsStackFind(ctx->ns_rendered, &ns_default)) {
        xmlC14NPrintNamespaces(&ns_default, ctx);
    }
    }
 
 
    /*
     * print out all elements from list
     */
    xmlListWalk(list, xmlC14NPrintNamespacesWalker, (void *) ctx);
 
    /*
     * Cleanup
     */
    xmlListDelete(list);
    return (0);
}
 
 
static int
xmlExcC14NProcessNamespacesAxis(xmlC14NCtxPtr ctx, xmlNodePtr cur, int visible)
{
    xmlNsPtr ns;
    xmlListPtr list;
    xmlAttrPtr attr;
    int already_rendered;
    int has_empty_ns = 0;
    int has_visibly_utilized_empty_ns = 0;
    int has_empty_ns_in_inclusive_list = 0;
 
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("processing namespaces axis (exc c14n)");
        return (-1);
    }
 
    if(!xmlC14NIsExclusive(ctx)) {
        xmlC14NErrParam("processing namespaces axis (exc c14n)");
        return (-1);
 
    }
 
    /*
     * Create a sorted list to store element namespaces
     */
    list = xmlListCreate(NULL, xmlC14NNsCompare);
    if (list == NULL) {
        xmlC14NErrInternal("creating namespaces list (exc c14n)");
        return (-1);
    }
 
    /*
     * process inclusive namespaces:
     * All namespace nodes appearing on inclusive ns list are
     * handled as provided in Canonical XML
     */
    if(ctx->inclusive_ns_prefixes != NULL) {
    xmlChar *prefix;
    int i;
 
    for (i = 0; ctx->inclusive_ns_prefixes[i] != NULL; ++i) {
        prefix = ctx->inclusive_ns_prefixes[i];
        /*
         * Special values for namespace with empty prefix
         */
            if (xmlStrEqual(prefix, BAD_CAST "#default")
                || xmlStrEqual(prefix, BAD_CAST "")) {
                prefix = NULL;
        has_empty_ns_in_inclusive_list = 1;
            }
 
        ns = xmlSearchNs(cur->doc, cur, prefix);
        if((ns != NULL) && !xmlC14NIsXmlNs(ns) && xmlC14NIsVisible(ctx, ns, cur)) {
        already_rendered = xmlC14NVisibleNsStackFind(ctx->ns_rendered, ns);
        if(visible) {
            xmlC14NVisibleNsStackAdd(ctx->ns_rendered, ns, cur);
        }
        if(!already_rendered) {
            xmlListInsert(list, ns);
        }
        if(xmlStrlen(ns->prefix) == 0) {
            has_empty_ns = 1;
        }
        }
    }
    }
 
    /* add node namespace */
    if(cur->ns != NULL) {
    ns = cur->ns;
    } else {
        ns = xmlSearchNs(cur->doc, cur, NULL);
    has_visibly_utilized_empty_ns = 1;
    }
    if((ns != NULL) && !xmlC14NIsXmlNs(ns)) {
    if(visible && xmlC14NIsVisible(ctx, ns, cur)) {
        if(!xmlExcC14NVisibleNsStackFind(ctx->ns_rendered, ns, ctx)) {
        xmlListInsert(list, ns);
        }
    }
    if(visible) {
        xmlC14NVisibleNsStackAdd(ctx->ns_rendered, ns, cur);
    }
    if(xmlStrlen(ns->prefix) == 0) {
        has_empty_ns = 1;
    }
    }
 
 
    /* add attributes */
    for(attr = cur->properties; attr != NULL; attr = attr->next) {
        /*
         * we need to check that attribute is visible and has non
         * default namespace (XML Namespaces: "default namespaces
     * do not apply directly to attributes")
         */
    if((attr->ns != NULL) && !xmlC14NIsXmlNs(attr->ns) && xmlC14NIsVisible(ctx, attr, cur)) {
        already_rendered = xmlExcC14NVisibleNsStackFind(ctx->ns_rendered, attr->ns, ctx);
        xmlC14NVisibleNsStackAdd(ctx->ns_rendered, attr->ns, cur);
        if(!already_rendered && visible) {
        xmlListInsert(list, attr->ns);
        }
        if(xmlStrlen(attr->ns->prefix) == 0) {
        has_empty_ns = 1;
        }
    } else if((attr->ns != NULL) && (xmlStrlen(attr->ns->prefix) == 0) && (xmlStrlen(attr->ns->href) == 0)) {
        has_visibly_utilized_empty_ns = 1;
    }
    }
 
    /*
     * Process xmlns=""
     */
    if(visible && has_visibly_utilized_empty_ns &&
        !has_empty_ns && !has_empty_ns_in_inclusive_list) {
        static xmlNs ns_default;
 
        memset(&ns_default, 0, sizeof(ns_default));
 
        already_rendered = xmlExcC14NVisibleNsStackFind(ctx->ns_rendered, &ns_default, ctx);
    if(!already_rendered) {
        xmlC14NPrintNamespaces(&ns_default, ctx);
    }
    } else if(visible && !has_empty_ns && has_empty_ns_in_inclusive_list) {
        static xmlNs ns_default;
 
        memset(&ns_default, 0, sizeof(ns_default));
        if(!xmlC14NVisibleNsStackFind(ctx->ns_rendered, &ns_default)) {
        xmlC14NPrintNamespaces(&ns_default, ctx);
    }
    }
 
 
 
    /*
     * print out all elements from list
     */
    xmlListWalk(list, xmlC14NPrintNamespacesWalker, (void *) ctx);
 
    /*
     * Cleanup
     */
    xmlListDelete(list);
    return (0);
}
 
 
/* todo: make it a define? */
static int
xmlC14NIsXmlAttr(xmlAttrPtr attr)
{
    return ((attr->ns != NULL) &&
           (xmlC14NIsXmlNs(attr->ns) != 0));
}
 
 
static int
xmlC14NAttrsCompare(const void *data1, const void *data2)
{
    const xmlAttrPtr attr1 = (const xmlAttrPtr) data1;
    const xmlAttrPtr attr2 = (const xmlAttrPtr) data2;
    int ret = 0;
 
    /*
     * Simple cases
     */
    if (attr1 == attr2)
        return (0);
    if (attr1 == NULL)
        return (-1);
    if (attr2 == NULL)
        return (1);
    if (attr1->ns == attr2->ns) {
        return (xmlStrcmp(attr1->name, attr2->name));
    }
 
    /*
     * Attributes in the default namespace are first
     * because the default namespace is not applied to
     * unqualified attributes
     */
    if (attr1->ns == NULL)
        return (-1);
    if (attr2->ns == NULL)
        return (1);
    if (attr1->ns->prefix == NULL)
        return (-1);
    if (attr2->ns->prefix == NULL)
        return (1);
 
    ret = xmlStrcmp(attr1->ns->href, attr2->ns->href);
    if (ret == 0) {
        ret = xmlStrcmp(attr1->name, attr2->name);
    }
    return (ret);
}
 
 
static int
xmlC14NPrintAttrs(const void *data, void *user)
{
    const xmlAttrPtr attr = (const xmlAttrPtr) data;
    xmlC14NCtxPtr ctx = (xmlC14NCtxPtr) user;
    xmlChar *value;
    xmlChar *buffer;
 
    if ((attr == NULL) || (ctx == NULL)) {
        xmlC14NErrParam("writing attributes");
        return (0);
    }
 
    xmlOutputBufferWriteString(ctx->buf, " ");
    if (attr->ns != NULL && xmlStrlen(attr->ns->prefix) > 0) {
        xmlOutputBufferWriteString(ctx->buf,
                                   (const char *) attr->ns->prefix);
        xmlOutputBufferWriteString(ctx->buf, ":");
    }
    xmlOutputBufferWriteString(ctx->buf, (const char *) attr->name);
    xmlOutputBufferWriteString(ctx->buf, "=\"");
 
    value = xmlNodeListGetString(ctx->doc, attr->children, 1);
    /* todo: should we log an error if value==NULL ? */
    if (value != NULL) {
        buffer = xmlC11NNormalizeAttr(value);
        xmlFree(value);
        if (buffer != NULL) {
            xmlOutputBufferWriteString(ctx->buf, (const char *) buffer);
            xmlFree(buffer);
        } else {
            xmlC14NErrInternal("normalizing attributes axis");
            return (0);
        }
    }
    xmlOutputBufferWriteString(ctx->buf, "\"");
    return (1);
}
 
static xmlAttrPtr
xmlC14NFindHiddenParentAttr(xmlC14NCtxPtr ctx, xmlNodePtr cur, const xmlChar * name, const xmlChar * ns)
{
    xmlAttrPtr res;
    while((cur != NULL) && (!xmlC14NIsVisible(ctx, cur, cur->parent))) {
        res = xmlHasNsProp(cur, name, ns);
        if(res != NULL) {
            return res;
        }
 
        cur = cur->parent;
    }
 
    return NULL;
}
 
static xmlAttrPtr
xmlC14NFixupBaseAttr(xmlC14NCtxPtr ctx, xmlAttrPtr xml_base_attr)
{
    xmlChar * res = NULL;
    xmlNodePtr cur;
    xmlAttrPtr attr;
    xmlChar * tmp_str;
    xmlChar * tmp_str2;
    int tmp_str_len;
 
    if ((ctx == NULL) || (xml_base_attr == NULL) || (xml_base_attr->parent == NULL)) {
        xmlC14NErrParam("processing xml:base attribute");
        return (NULL);
    }
 
    /* start from current value */
    res = xmlNodeListGetString(ctx->doc, xml_base_attr->children, 1);
    if(res == NULL) {
        xmlC14NErrInternal("processing xml:base attribute - can't get attr value");
        return (NULL);
    }
 
    /* go up the stack until we find a node that we rendered already */
    cur = xml_base_attr->parent->parent;
    while((cur != NULL) && (!xmlC14NIsVisible(ctx, cur, cur->parent))) {
        attr = xmlHasNsProp(cur, BAD_CAST "base", XML_XML_NAMESPACE);
        if(attr != NULL) {
            /* get attr value */
            tmp_str = xmlNodeListGetString(ctx->doc, attr->children, 1);
            if(tmp_str == NULL) {
                xmlFree(res);
 
                xmlC14NErrInternal("processing xml:base attribute - can't get attr value");
                return (NULL);
            }
 
            /* we need to add '/' if our current base uri ends with '..' or '.'
            to ensure that we are forced to go "up" all the time */
            tmp_str_len = xmlStrlen(tmp_str);
            if(tmp_str_len > 1 && tmp_str[tmp_str_len - 2] == '.') {
                tmp_str2 = xmlStrcat(tmp_str, BAD_CAST "/");
                if(tmp_str2 == NULL) {
                    xmlFree(tmp_str);
                    xmlFree(res);
 
                    xmlC14NErrInternal("processing xml:base attribute - can't modify uri");
                    return (NULL);
                }
 
                tmp_str = tmp_str2;
            }
 
            /* build uri */
            tmp_str2 = xmlBuildURI(res, tmp_str);
            if(tmp_str2 == NULL) {
                xmlFree(tmp_str);
                xmlFree(res);
 
                xmlC14NErrInternal("processing xml:base attribute - can't construct uri");
                return (NULL);
            }
 
            /* cleanup and set the new res */
            xmlFree(tmp_str);
            xmlFree(res);
            res = tmp_str2;
        }
 
        /* next */
        cur = cur->parent;
    }
 
    /* check if result uri is empty or not */
    if((res == NULL) || xmlStrEqual(res, BAD_CAST "")) {
        xmlFree(res);
        return (NULL);
    }
 
    /* create and return the new attribute node */
    attr = xmlNewNsProp(NULL, xml_base_attr->ns, BAD_CAST "base", res);
    if(attr == NULL) {
        xmlFree(res);
 
        xmlC14NErrInternal("processing xml:base attribute - can't construct attribute");
        return (NULL);
    }
 
    /* done */
    xmlFree(res);
    return (attr);
}
 
static int
xmlC14NProcessAttrsAxis(xmlC14NCtxPtr ctx, xmlNodePtr cur, int parent_visible)
{
    xmlAttrPtr attr;
    xmlListPtr list;
    xmlAttrPtr attrs_to_delete = NULL;
 
    /* special processing for 1.1 spec */
    xmlAttrPtr xml_base_attr = NULL;
    xmlAttrPtr xml_lang_attr = NULL;
    xmlAttrPtr xml_space_attr = NULL;
 
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("processing attributes axis");
        return (-1);
    }
 
    /*
     * Create a sorted list to store element attributes
     */
    list = xmlListCreate(NULL, xmlC14NAttrsCompare);
    if (list == NULL) {
        xmlC14NErrInternal("creating attributes list");
        return (-1);
    }
 
    switch(ctx->mode) {
    case XML_C14N_1_0:
        /* The processing of an element node E MUST be modified slightly when an XPath node-set is
         * given as input and the element's parent is omitted from the node-set. The method for processing
         * the attribute axis of an element E in the node-set is enhanced. All element nodes along E's
         * ancestor axis are examined for nearest occurrences of attributes in the xml namespace, such
         * as xml:lang and xml:space (whether or not they are in the node-set). From this list of attributes,
         * remove any that are in E's attribute axis (whether or not they are in the node-set). Then,
         * lexicographically merge this attribute list with the nodes of E's attribute axis that are in
         * the node-set. The result of visiting the attribute axis is computed by processing the attribute
         * nodes in this merged attribute list.
         */
 
        /*
         * Add all visible attributes from current node.
         */
        attr = cur->properties;
        while (attr != NULL) {
            /* check that attribute is visible */
            if (xmlC14NIsVisible(ctx, attr, cur)) {
                xmlListInsert(list, attr);
            }
            attr = attr->next;
        }
 
        /*
         * Handle xml attributes
         */
        if (parent_visible && (cur->parent != NULL) &&
            (!xmlC14NIsVisible(ctx, cur->parent, cur->parent->parent)))
        {
            xmlNodePtr tmp;
 
            /*
             * If XPath node-set is not specified then the parent is always
             * visible!
             */
            tmp = cur->parent;
            while (tmp != NULL) {
                attr = tmp->properties;
                while (attr != NULL) {
                    if (xmlC14NIsXmlAttr(attr) != 0) {
                        if (xmlListSearch(list, attr) == NULL) {
                            xmlListInsert(list, attr);
                        }
                    }
                    attr = attr->next;
                }
                tmp = tmp->parent;
            }
        }
 
        /* done */
        break;
    case XML_C14N_EXCLUSIVE_1_0:
        /* attributes in the XML namespace, such as xml:lang and xml:space
         * are not imported into orphan nodes of the document subset
         */
 
        /*
         * Add all visible attributes from current node.
         */
        attr = cur->properties;
        while (attr != NULL) {
            /* check that attribute is visible */
            if (xmlC14NIsVisible(ctx, attr, cur)) {
                xmlListInsert(list, attr);
            }
            attr = attr->next;
        }
 
        /* do nothing special for xml attributes */
        break;
    case XML_C14N_1_1:
        /* The processing of an element node E MUST be modified slightly when an XPath node-set is
         * given as input and some of the element's ancestors are omitted from the node-set.
         *
         * Simple inheritable attributes are attributes that have a value that requires at most a simple
         * redeclaration. This redeclaration is done by supplying a new value in the child axis. The
         * redeclaration of a simple inheritable attribute A contained in one of E's ancestors is done
         * by supplying a value to an attribute Ae inside E with the same name. Simple inheritable attributes
         * are xml:lang and xml:space.
         *
         * The method for processing the attribute axis of an element E in the node-set is hence enhanced.
         * All element nodes along E's ancestor axis are examined for the nearest occurrences of simple
         * inheritable attributes in the xml namespace, such as xml:lang and xml:space (whether or not they
         * are in the node-set). From this list of attributes, any simple inheritable attributes that are
         * already in E's attribute axis (whether or not they are in the node-set) are removed. Then,
         * lexicographically merge this attribute list with the nodes of E's attribute axis that are in
         * the node-set. The result of visiting the attribute axis is computed by processing the attribute
         * nodes in this merged attribute list.
         *
         * The xml:id attribute is not a simple inheritable attribute and no processing of these attributes is
         * performed.
         *
         * The xml:base attribute is not a simple inheritable attribute and requires special processing beyond
         * a simple redeclaration.
         *
         * Attributes in the XML namespace other than xml:base, xml:id, xml:lang, and xml:space MUST be processed
         * as ordinary attributes.
         */
 
        /*
         * Add all visible attributes from current node.
         */
        attr = cur->properties;
        while (attr != NULL) {
            /* special processing for XML attribute kiks in only when we have invisible parents */
            if ((!parent_visible) || (xmlC14NIsXmlAttr(attr) == 0)) {
                /* check that attribute is visible */
                if (xmlC14NIsVisible(ctx, attr, cur)) {
                    xmlListInsert(list, attr);
                }
            } else {
                int matched = 0;
 
                /* check for simple inheritance attributes */
                if((!matched) && (xml_lang_attr == NULL) && xmlStrEqual(attr->name, BAD_CAST "lang")) {
                    xml_lang_attr = attr;
                    matched = 1;
                }
                if((!matched) && (xml_space_attr == NULL) && xmlStrEqual(attr->name, BAD_CAST "space")) {
                    xml_space_attr = attr;
                    matched = 1;
                }
 
                /* check for base attr */
                if((!matched) && (xml_base_attr == NULL) && xmlStrEqual(attr->name, BAD_CAST "base")) {
                    xml_base_attr = attr;
                    matched = 1;
                }
 
                /* otherwise, it is a normal attribute, so just check if it is visible */
                if((!matched) && xmlC14NIsVisible(ctx, attr, cur)) {
                    xmlListInsert(list, attr);
                }
            }
 
            /* move to the next one */
            attr = attr->next;
        }
 
        /* special processing for XML attribute kiks in only when we have invisible parents */
        if ((parent_visible)) {
 
            /* simple inheritance attributes - copy */
            if(xml_lang_attr == NULL) {
                xml_lang_attr = xmlC14NFindHiddenParentAttr(ctx, cur->parent, BAD_CAST "lang", XML_XML_NAMESPACE);
            }
            if(xml_lang_attr != NULL) {
                xmlListInsert(list, xml_lang_attr);
            }
            if(xml_space_attr == NULL) {
                xml_space_attr = xmlC14NFindHiddenParentAttr(ctx, cur->parent, BAD_CAST "space", XML_XML_NAMESPACE);
            }
            if(xml_space_attr != NULL) {
                xmlListInsert(list, xml_space_attr);
            }
 
            /* base uri attribute - fix up */
            if(xml_base_attr == NULL) {
                /* if we don't have base uri attribute, check if we have a "hidden" one above */
                xml_base_attr = xmlC14NFindHiddenParentAttr(ctx, cur->parent, BAD_CAST "base", XML_XML_NAMESPACE);
            }
            if(xml_base_attr != NULL) {
                xml_base_attr = xmlC14NFixupBaseAttr(ctx, xml_base_attr);
                if(xml_base_attr != NULL) {
                    xmlListInsert(list, xml_base_attr);
 
                    /* note that we MUST delete returned attr node ourselves! */
                    xml_base_attr->next = attrs_to_delete;
                    attrs_to_delete = xml_base_attr;
                }
            }
        }
 
        /* done */
        break;
    }
 
    /*
     * print out all elements from list
     */
    xmlListWalk(list, xmlC14NPrintAttrs, (void *) ctx);
 
    /*
     * Cleanup
     */
    xmlFreePropList(attrs_to_delete);
    xmlListDelete(list);
    return (0);
}
 
static int
xmlC14NCheckForRelativeNamespaces(xmlC14NCtxPtr ctx, xmlNodePtr cur)
{
    xmlNsPtr ns;
 
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("checking for relative namespaces");
        return (-1);
    }
 
    ns = cur->nsDef;
    while (ns != NULL) {
        if (xmlStrlen(ns->href) > 0) {
            xmlURIPtr uri;
 
            uri = xmlParseURI((const char *) ns->href);
            if (uri == NULL) {
                xmlC14NErrInternal("parsing namespace uri");
                return (-1);
            }
            if (xmlStrlen((const xmlChar *) uri->scheme) == 0) {
                xmlC14NErrRelativeNamespace(uri->scheme);
                xmlFreeURI(uri);
                return (-1);
            }
            xmlFreeURI(uri);
        }
        ns = ns->next;
    }
    return (0);
}
 
static int
xmlC14NProcessElementNode(xmlC14NCtxPtr ctx, xmlNodePtr cur, int visible)
{
    int ret;
    xmlC14NVisibleNsStack state;
    int parent_is_doc = 0;
 
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("processing element node");
        return (-1);
    }
 
    /*
     * Check relative relative namespaces:
     * implementations of XML canonicalization MUST report an operation
     * failure on documents containing relative namespace URIs.
     */
    if (xmlC14NCheckForRelativeNamespaces(ctx, cur) < 0) {
        xmlC14NErrInternal("checking for relative namespaces");
        return (-1);
    }
 
 
    /*
     * Save ns_rendered stack position
     */
    memset(&state, 0, sizeof(state));
    xmlC14NVisibleNsStackSave(ctx->ns_rendered, &state);
 
    if (visible) {
        if (ctx->parent_is_doc) {
        /* save this flag into the stack */
        parent_is_doc = ctx->parent_is_doc;
        ctx->parent_is_doc = 0;
            ctx->pos = XMLC14N_INSIDE_DOCUMENT_ELEMENT;
        }
        xmlOutputBufferWriteString(ctx->buf, "<");
 
        if ((cur->ns != NULL) && (xmlStrlen(cur->ns->prefix) > 0)) {
            xmlOutputBufferWriteString(ctx->buf,
                                       (const char *) cur->ns->prefix);
            xmlOutputBufferWriteString(ctx->buf, ":");
        }
        xmlOutputBufferWriteString(ctx->buf, (const char *) cur->name);
    }
 
    if (!xmlC14NIsExclusive(ctx)) {
        ret = xmlC14NProcessNamespacesAxis(ctx, cur, visible);
    } else {
        ret = xmlExcC14NProcessNamespacesAxis(ctx, cur, visible);
    }
    if (ret < 0) {
        xmlC14NErrInternal("processing namespaces axis");
        return (-1);
    }
    /* todo: shouldn't this go to "visible only"? */
    if(visible) {
    xmlC14NVisibleNsStackShift(ctx->ns_rendered);
    }
 
    ret = xmlC14NProcessAttrsAxis(ctx, cur, visible);
    if (ret < 0) {
    xmlC14NErrInternal("processing attributes axis");
    return (-1);
    }
 
    if (visible) {
        xmlOutputBufferWriteString(ctx->buf, ">");
    }
    if (cur->children != NULL) {
        ret = xmlC14NProcessNodeList(ctx, cur->children);
        if (ret < 0) {
            xmlC14NErrInternal("processing childrens list");
            return (-1);
        }
    }
    if (visible) {
        xmlOutputBufferWriteString(ctx->buf, "</");
        if ((cur->ns != NULL) && (xmlStrlen(cur->ns->prefix) > 0)) {
            xmlOutputBufferWriteString(ctx->buf,
                                       (const char *) cur->ns->prefix);
            xmlOutputBufferWriteString(ctx->buf, ":");
        }
        xmlOutputBufferWriteString(ctx->buf, (const char *) cur->name);
        xmlOutputBufferWriteString(ctx->buf, ">");
        if (parent_is_doc) {
        /* restore this flag from the stack for next node */
            ctx->parent_is_doc = parent_is_doc;
        ctx->pos = XMLC14N_AFTER_DOCUMENT_ELEMENT;
        }
    }
 
    /*
     * Restore ns_rendered stack position
     */
    xmlC14NVisibleNsStackRestore(ctx->ns_rendered, &state);
    return (0);
}
 
static int
xmlC14NProcessNode(xmlC14NCtxPtr ctx, xmlNodePtr cur)
{
    int ret = 0;
    int visible;
 
    if ((ctx == NULL) || (cur == NULL)) {
        xmlC14NErrParam("processing node");
        return (-1);
    }
 
    visible = xmlC14NIsVisible(ctx, cur, cur->parent);
    switch (cur->type) {
        case XML_ELEMENT_NODE:
            ret = xmlC14NProcessElementNode(ctx, cur, visible);
            break;
        case XML_CDATA_SECTION_NODE:
        case XML_TEXT_NODE:
            /*
             * Text Nodes
             * the string value, except all ampersands are replaced
             * by &amp;, all open angle brackets (<) are replaced by &lt;, all closing
             * angle brackets (>) are replaced by &gt;, and all #xD characters are
             * replaced by &#xD;.
             */
            /* cdata sections are processed as text nodes */
            /* todo: verify that cdata sections are included in XPath nodes set */
            if ((visible) && (cur->content != NULL)) {
                xmlChar *buffer;
 
                buffer = xmlC11NNormalizeText(cur->content);
                if (buffer != NULL) {
                    xmlOutputBufferWriteString(ctx->buf,
                                               (const char *) buffer);
                    xmlFree(buffer);
                } else {
                    xmlC14NErrInternal("normalizing text node");
                    return (-1);
                }
            }
            break;
        case XML_PI_NODE:
            /*
             * Processing Instruction (PI) Nodes-
             * The opening PI symbol (<?), the PI target name of the node,
             * a leading space and the string value if it is not empty, and
             * the closing PI symbol (?>). If the string value is empty,
             * then the leading space is not added. Also, a trailing #xA is
             * rendered after the closing PI symbol for PI children of the
             * root node with a lesser document order than the document
             * element, and a leading #xA is rendered before the opening PI
             * symbol of PI children of the root node with a greater document
             * order than the document element.
             */
            if (visible) {
                if (ctx->pos == XMLC14N_AFTER_DOCUMENT_ELEMENT) {
                    xmlOutputBufferWriteString(ctx->buf, "\x0A<?");
                } else {
                    xmlOutputBufferWriteString(ctx->buf, "<?");
                }
 
                xmlOutputBufferWriteString(ctx->buf,
                                           (const char *) cur->name);
                if ((cur->content != NULL) && (*(cur->content) != '\0')) {
                    xmlChar *buffer;
 
                    xmlOutputBufferWriteString(ctx->buf, " ");
 
                    /* todo: do we need to normalize pi? */
                    buffer = xmlC11NNormalizePI(cur->content);
                    if (buffer != NULL) {
                        xmlOutputBufferWriteString(ctx->buf,
                                                   (const char *) buffer);
                        xmlFree(buffer);
                    } else {
                        xmlC14NErrInternal("normalizing pi node");
                        return (-1);
                    }
                }
 
                if (ctx->pos == XMLC14N_BEFORE_DOCUMENT_ELEMENT) {
                    xmlOutputBufferWriteString(ctx->buf, "?>\x0A");
                } else {
                    xmlOutputBufferWriteString(ctx->buf, "?>");
                }
            }
            break;
        case XML_COMMENT_NODE:
            /*
             * Comment Nodes
             * Nothing if generating canonical XML without  comments. For
             * canonical XML with comments, generate the opening comment
             * symbol (<!--), the string value of the node, and the
             * closing comment symbol (-->). Also, a trailing #xA is rendered
             * after the closing comment symbol for comment children of the
             * root node with a lesser document order than the document
             * element, and a leading #xA is rendered before the opening
             * comment symbol of comment children of the root node with a
             * greater document order than the document element. (Comment
             * children of the root node represent comments outside of the
             * top-level document element and outside of the document type
             * declaration).
             */
            if (visible && ctx->with_comments) {
                if (ctx->pos == XMLC14N_AFTER_DOCUMENT_ELEMENT) {
                    xmlOutputBufferWriteString(ctx->buf, "\x0A<!--");
                } else {
                    xmlOutputBufferWriteString(ctx->buf, "<!--");
                }
 
                if (cur->content != NULL) {
                    xmlChar *buffer;
 
                    /* todo: do we need to normalize comment? */
                    buffer = xmlC11NNormalizeComment(cur->content);
                    if (buffer != NULL) {
                        xmlOutputBufferWriteString(ctx->buf,
                                                   (const char *) buffer);
                        xmlFree(buffer);
                    } else {
                        xmlC14NErrInternal("normalizing comment node");
                        return (-1);
                    }
                }
 
                if (ctx->pos == XMLC14N_BEFORE_DOCUMENT_ELEMENT) {
                    xmlOutputBufferWriteString(ctx->buf, "-->\x0A");
                } else {
                    xmlOutputBufferWriteString(ctx->buf, "-->");
                }
            }
            break;
        case XML_DOCUMENT_NODE:
        case XML_DOCUMENT_FRAG_NODE:   /* should be processed as document? */
#ifdef LIBXML_HTML_ENABLED
        case XML_HTML_DOCUMENT_NODE:   /* should be processed as document? */
#endif
            if (cur->children != NULL) {
                ctx->pos = XMLC14N_BEFORE_DOCUMENT_ELEMENT;
                ctx->parent_is_doc = 1;
                ret = xmlC14NProcessNodeList(ctx, cur->children);
            }
            break;
 
        case XML_ATTRIBUTE_NODE:
            xmlC14NErrInvalidNode("XML_ATTRIBUTE_NODE", "processing node");
            return (-1);
        case XML_NAMESPACE_DECL:
            xmlC14NErrInvalidNode("XML_NAMESPACE_DECL", "processing node");
            return (-1);
        case XML_ENTITY_REF_NODE:
            xmlC14NErrInvalidNode("XML_ENTITY_REF_NODE", "processing node");
            return (-1);
        case XML_ENTITY_NODE:
            xmlC14NErrInvalidNode("XML_ENTITY_NODE", "processing node");
            return (-1);
 
        case XML_DOCUMENT_TYPE_NODE:
        case XML_NOTATION_NODE:
        case XML_DTD_NODE:
        case XML_ELEMENT_DECL:
        case XML_ATTRIBUTE_DECL:
        case XML_ENTITY_DECL:
#ifdef LIBXML_XINCLUDE_ENABLED
        case XML_XINCLUDE_START:
        case XML_XINCLUDE_END:
#endif
            /*
             * should be ignored according to "W3C Canonical XML"
             */
            break;
        default:
            xmlC14NErrUnknownNode(cur->type, "processing node");
            return (-1);
    }
 
    return (ret);
}
 
static int
xmlC14NProcessNodeList(xmlC14NCtxPtr ctx, xmlNodePtr cur)
{
    int ret;
 
    if (ctx == NULL) {
        xmlC14NErrParam("processing node list");
        return (-1);
    }
 
    for (ret = 0; cur != NULL && ret >= 0; cur = cur->next) {
        ret = xmlC14NProcessNode(ctx, cur);
    }
    return (ret);
}
 
 
static void
xmlC14NFreeCtx(xmlC14NCtxPtr ctx)
{
    if (ctx == NULL) {
        xmlC14NErrParam("freeing context");
        return;
    }
 
    if (ctx->ns_rendered != NULL) {
        xmlC14NVisibleNsStackDestroy(ctx->ns_rendered);
    }
    xmlFree(ctx);
}
 
static xmlC14NCtxPtr
xmlC14NNewCtx(xmlDocPtr doc,
          xmlC14NIsVisibleCallback is_visible_callback, void* user_data,
              xmlC14NMode mode, xmlChar ** inclusive_ns_prefixes,
              int with_comments, xmlOutputBufferPtr buf)
{
    xmlC14NCtxPtr ctx = NULL;
 
    if ((doc == NULL) || (buf == NULL)) {
        xmlC14NErrParam("creating new context");
        return (NULL);
    }
 
    /*
     *  Validate the encoding output buffer encoding
     */
    if (buf->encoder != NULL) {
        xmlC14NErr(ctx, (xmlNodePtr) doc, XML_C14N_REQUIRES_UTF8,
"xmlC14NNewCtx: output buffer encoder != NULL but C14N requires UTF8 output\n");
        return (NULL);
    }
 
    /*
     * Allocate a new xmlC14NCtxPtr and fill the fields.
     */
    ctx = (xmlC14NCtxPtr) xmlMalloc(sizeof(xmlC14NCtx));
    if (ctx == NULL) {
    xmlC14NErrMemory("creating context");
        return (NULL);
    }
    memset(ctx, 0, sizeof(xmlC14NCtx));
 
    /*
     * initialize C14N context
     */
    ctx->doc = doc;
    ctx->with_comments = with_comments;
    ctx->is_visible_callback = is_visible_callback;
    ctx->user_data = user_data;
    ctx->buf = buf;
    ctx->parent_is_doc = 1;
    ctx->pos = XMLC14N_BEFORE_DOCUMENT_ELEMENT;
    ctx->ns_rendered = xmlC14NVisibleNsStackCreate();
 
    if(ctx->ns_rendered == NULL) {
        xmlC14NErr(ctx, (xmlNodePtr) doc, XML_C14N_CREATE_STACK,
           "xmlC14NNewCtx: xmlC14NVisibleNsStackCreate failed\n");
    xmlC14NFreeCtx(ctx);
        return (NULL);
    }
 
    /*
     * Set "mode" flag and remember list of inclusive prefixes
     * for exclusive c14n
     */
    ctx->mode = mode;
    if(xmlC14NIsExclusive(ctx)) {
        ctx->inclusive_ns_prefixes = inclusive_ns_prefixes;
    }
    return (ctx);
}
 
int
xmlC14NExecute(xmlDocPtr doc, xmlC14NIsVisibleCallback is_visible_callback,
     void* user_data, int mode, xmlChar **inclusive_ns_prefixes,
     int with_comments, xmlOutputBufferPtr buf) {
 
    xmlC14NCtxPtr ctx;
    xmlC14NMode c14n_mode = XML_C14N_1_0;
    int ret;
 
    if ((buf == NULL) || (doc == NULL)) {
        xmlC14NErrParam("executing c14n");
        return (-1);
    }
 
    /* for backward compatibility, we have to have "mode" as "int"
       and here we check that user gives valid value */
    switch(mode) {
    case XML_C14N_1_0:
    case XML_C14N_EXCLUSIVE_1_0:
    case XML_C14N_1_1:
         c14n_mode = (xmlC14NMode)mode;
         break;
    default:
        xmlC14NErrParam("invalid mode for executing c14n");
        return (-1);
    }
 
    /*
     *  Validate the encoding output buffer encoding
     */
    if (buf->encoder != NULL) {
        xmlC14NErr(NULL, (xmlNodePtr) doc, XML_C14N_REQUIRES_UTF8,
"xmlC14NExecute: output buffer encoder != NULL but C14N requires UTF8 output\n");
        return (-1);
    }
 
    ctx = xmlC14NNewCtx(doc, is_visible_callback, user_data,
                c14n_mode, inclusive_ns_prefixes,
                    with_comments, buf);
    if (ctx == NULL) {
        xmlC14NErr(NULL, (xmlNodePtr) doc, XML_C14N_CREATE_CTXT,
           "xmlC14NExecute: unable to create C14N context\n");
        return (-1);
    }
 
 
 
    /*
     * Root Node
     * The root node is the parent of the top-level document element. The
     * result of processing each of its child nodes that is in the node-set
     * in document order. The root node does not generate a byte order mark,
     * XML declaration, nor anything from within the document type
     * declaration.
     */
    if (doc->children != NULL) {
        ret = xmlC14NProcessNodeList(ctx, doc->children);
        if (ret < 0) {
            xmlC14NErrInternal("processing docs children list");
            xmlC14NFreeCtx(ctx);
            return (-1);
        }
    }
 
    /*
     * Flush buffer to get number of bytes written
     */
    ret = xmlOutputBufferFlush(buf);
    if (ret < 0) {
        xmlC14NErrInternal("flushing output buffer");
        xmlC14NFreeCtx(ctx);
        return (-1);
    }
 
    /*
     * Cleanup
     */
    xmlC14NFreeCtx(ctx);
    return (ret);
}
 
int
xmlC14NDocSaveTo(xmlDocPtr doc, xmlNodeSetPtr nodes,
                 int mode, xmlChar ** inclusive_ns_prefixes,
                 int with_comments, xmlOutputBufferPtr buf) {
    return(xmlC14NExecute(doc,
            xmlC14NIsNodeInNodeset,
            nodes,
            mode,
            inclusive_ns_prefixes,
            with_comments,
            buf));
}
 
 
int
xmlC14NDocDumpMemory(xmlDocPtr doc, xmlNodeSetPtr nodes,
                     int mode, xmlChar ** inclusive_ns_prefixes,
                     int with_comments, xmlChar ** doc_txt_ptr)
{
    int ret;
    xmlOutputBufferPtr buf;
 
    if (doc_txt_ptr == NULL) {
        xmlC14NErrParam("dumping doc to memory");
        return (-1);
    }
 
    *doc_txt_ptr = NULL;
 
    /*
     * create memory buffer with UTF8 (default) encoding
     */
    buf = xmlAllocOutputBuffer(NULL);
    if (buf == NULL) {
        xmlC14NErrMemory("creating output buffer");
        return (-1);
    }
 
    /*
     * canonize document and write to buffer
     */
    ret = xmlC14NDocSaveTo(doc, nodes, mode, inclusive_ns_prefixes,
                           with_comments, buf);
    if (ret < 0) {
        xmlC14NErrInternal("saving doc to output buffer");
        (void) xmlOutputBufferClose(buf);
        return (-1);
    }
 
    ret = xmlBufUse(buf->buffer);
    if (ret >= 0) {
        *doc_txt_ptr = xmlStrndup(xmlBufContent(buf->buffer), ret);
    }
    (void) xmlOutputBufferClose(buf);
 
    if ((*doc_txt_ptr == NULL) && (ret >= 0)) {
        xmlC14NErrMemory("copying canonicalized document");
        return (-1);
    }
    return (ret);
}
 
int
xmlC14NDocSave(xmlDocPtr doc, xmlNodeSetPtr nodes,
               int mode, xmlChar ** inclusive_ns_prefixes,
               int with_comments, const char *filename, int compression)
{
    xmlOutputBufferPtr buf;
    int ret;
 
    if (filename == NULL) {
        xmlC14NErrParam("saving doc");
        return (-1);
    }
#ifdef LIBXML_ZLIB_ENABLED
    if (compression < 0)
        compression = xmlGetCompressMode();
#endif
 
    /*
     * save the content to a temp buffer, use default UTF8 encoding.
     */
    buf = xmlOutputBufferCreateFilename(filename, NULL, compression);
    if (buf == NULL) {
        xmlC14NErrInternal("creating temporary filename");
        return (-1);
    }
 
    /*
     * canonize document and write to buffer
     */
    ret = xmlC14NDocSaveTo(doc, nodes, mode, inclusive_ns_prefixes,
                           with_comments, buf);
    if (ret < 0) {
        xmlC14NErrInternal("canonize document to buffer");
        (void) xmlOutputBufferClose(buf);
        return (-1);
    }
 
    /*
     * get the numbers of bytes written
     */
    ret = xmlOutputBufferClose(buf);
    return (ret);
}
 
 
 
/*
 * Macro used to grow the current buffer.
 */
#define growBufferReentrant() {                     \
    buffer_size *= 2;                           \
    buffer = (xmlChar *)                        \
        xmlRealloc(buffer, buffer_size * sizeof(xmlChar));  \
    if (buffer == NULL) {                       \
    xmlC14NErrMemory("growing buffer");             \
    return(NULL);                           \
    }                                   \
}
 
static xmlChar *
xmlC11NNormalizeString(const xmlChar * input,
                       xmlC14NNormalizationMode mode)
{
    const xmlChar *cur = input;
    xmlChar *buffer = NULL;
    xmlChar *out = NULL;
    int buffer_size = 0;
 
    if (input == NULL)
        return (NULL);
 
    /*
     * allocate an translation buffer.
     */
    buffer_size = 1000;
    buffer = (xmlChar *) xmlMallocAtomic(buffer_size * sizeof(xmlChar));
    if (buffer == NULL) {
    xmlC14NErrMemory("allocating buffer");
        return (NULL);
    }
    out = buffer;
 
    while (*cur != '\0') {
        if ((out - buffer) > (buffer_size - 10)) {
            int indx = out - buffer;
 
            growBufferReentrant();
            out = &buffer[indx];
        }
 
        if ((*cur == '<') && ((mode == XMLC14N_NORMALIZE_ATTR) ||
                              (mode == XMLC14N_NORMALIZE_TEXT))) {
            *out++ = '&';
            *out++ = 'l';
            *out++ = 't';
            *out++ = ';';
        } else if ((*cur == '>') && (mode == XMLC14N_NORMALIZE_TEXT)) {
            *out++ = '&';
            *out++ = 'g';
            *out++ = 't';
            *out++ = ';';
        } else if ((*cur == '&') && ((mode == XMLC14N_NORMALIZE_ATTR) ||
                                     (mode == XMLC14N_NORMALIZE_TEXT))) {
            *out++ = '&';
            *out++ = 'a';
            *out++ = 'm';
            *out++ = 'p';
            *out++ = ';';
        } else if ((*cur == '"') && (mode == XMLC14N_NORMALIZE_ATTR)) {
            *out++ = '&';
            *out++ = 'q';
            *out++ = 'u';
            *out++ = 'o';
            *out++ = 't';
            *out++ = ';';
        } else if ((*cur == '\x09') && (mode == XMLC14N_NORMALIZE_ATTR)) {
            *out++ = '&';
            *out++ = '#';
            *out++ = 'x';
            *out++ = '9';
            *out++ = ';';
        } else if ((*cur == '\x0A') && (mode == XMLC14N_NORMALIZE_ATTR)) {
            *out++ = '&';
            *out++ = '#';
            *out++ = 'x';
            *out++ = 'A';
            *out++ = ';';
        } else if ((*cur == '\x0D') && ((mode == XMLC14N_NORMALIZE_ATTR) ||
                                        (mode == XMLC14N_NORMALIZE_TEXT) ||
                                        (mode == XMLC14N_NORMALIZE_COMMENT) ||
                    (mode == XMLC14N_NORMALIZE_PI))) {
            *out++ = '&';
            *out++ = '#';
            *out++ = 'x';
            *out++ = 'D';
            *out++ = ';';
        } else {
            /*
             * Works because on UTF-8, all extended sequences cannot
             * result in bytes in the ASCII range.
             */
            *out++ = *cur;
        }
        cur++;
    }
    *out = 0;
    return (buffer);
}
#endif /* LIBXML_OUTPUT_ENABLED */
 
#endif /* LIBXML_C14N_ENABLED */