namespaces.c

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/*
 * namespaces.c: Implementation of the XSLT namespaces handling
 *
 * Reference:
 *   http://www.w3.org/TR/1999/REC-xslt-19991116
 *
 * See Copyright for the status of this software.
 *
 * daniel@veillard.com
 */

#define IN_LIBXSLT
#include "libxslt.h"

#include <string.h>

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_MATH_H
#include <math.h>
#endif
#ifdef HAVE_FLOAT_H
#include <float.h>
#endif
#ifdef HAVE_IEEEFP_H
#include <ieeefp.h>
#endif
#ifdef HAVE_NAN_H
#include <nan.h>
#endif
#ifdef HAVE_CTYPE_H
#include <ctype.h>
#endif
#ifndef XSLT_NEED_TRIO
#include <stdio.h>
#else
#include <trio.h>
#endif

#include <libxml/xmlmemory.h>
#include <libxml/tree.h>
#include <libxml/hash.h>
#include <libxml/xmlerror.h>
#include <libxml/uri.h>
#include "xslt.h"
#include "xsltInternals.h"
#include "xsltutils.h"
#include "namespaces.h"
#include "imports.h"

/************************************************************************
 *                                  *
 *          Module interfaces               *
 *                                  *
 ************************************************************************/

#ifdef XSLT_REFACTORED  
static xsltNsAliasPtr
xsltNewNsAlias(xsltCompilerCtxtPtr cctxt)
{
    xsltNsAliasPtr ret;

    if (cctxt == NULL)
    return(NULL);

    ret = (xsltNsAliasPtr) xmlMalloc(sizeof(xsltNsAlias));
    if (ret == NULL) {
    xsltTransformError(NULL, cctxt->style, NULL,
        "Internal error in xsltNewNsAlias(): Memory allocation failed.\n");
    cctxt->style->errors++;
    return(NULL);
    }
    memset(ret, 0, sizeof(xsltNsAlias));    
    /*
    * TODO: Store the item at current stylesheet-level.
    */
    ret->next = cctxt->nsAliases;
    cctxt->nsAliases = ret;       

    return(ret);
}
#endif /* XSLT_REFACTORED */

void
xsltNamespaceAlias(xsltStylesheetPtr style, xmlNodePtr node)
{
    xmlChar *resultPrefix = NULL;
    xmlChar *stylePrefix = NULL;
    xmlNsPtr literalNs = NULL;
    xmlNsPtr targetNs = NULL;
 
#ifdef XSLT_REFACTORED 
    xsltNsAliasPtr alias;

    if ((style == NULL) || (node == NULL))
    return;

    /*
    * SPEC XSLT 1.0:
    *  "If a namespace URI is declared to be an alias for multiple
    *  different namespace URIs, then the declaration with the highest
    *  import precedence is used. It is an error if there is more than
    *  one such declaration. An XSLT processor may signal the error;
    *  if it does not signal the error, it must recover by choosing,
    *  from amongst the declarations with the highest import precedence,
    *  the one that occurs last in the stylesheet."
    *
    * SPEC TODO: Check for the errors mentioned above.
    */
    /*
    * NOTE that the XSLT 2.0 also *does* use the NULL namespace if
    *  "#default" is used and there's no default namespace is scope.
    *  I.e., this is *not* an error. 
    *  Most XSLT 1.0 implementations work this way.
    *  The XSLT 1.0 spec has nothing to say on the subject. 
    */
    /*
    * Attribute "stylesheet-prefix".
    */
    stylePrefix = xmlGetNsProp(node, (const xmlChar *)"stylesheet-prefix", NULL);
    if (stylePrefix == NULL) {
    xsltTransformError(NULL, style, node,
        "The attribute 'stylesheet-prefix' is missing.\n");
    return;
    }
    if (xmlStrEqual(stylePrefix, (const xmlChar *)"#default"))
    literalNs = xmlSearchNs(node->doc, node, NULL); 
    else {
    literalNs = xmlSearchNs(node->doc, node, stylePrefix);
    if (literalNs == NULL) {
        xsltTransformError(NULL, style, node,
            "Attribute 'stylesheet-prefix': There's no namespace "
        "declaration in scope for the prefix '%s'.\n",
            stylePrefix);
        goto error;
    }
    }
    /*
    * Attribute "result-prefix".
    */
    resultPrefix = xmlGetNsProp(node, (const xmlChar *)"result-prefix", NULL);
    if (resultPrefix == NULL) {
    xsltTransformError(NULL, style, node,
        "The attribute 'result-prefix' is missing.\n");
    goto error;
    }        
    if (xmlStrEqual(resultPrefix, (const xmlChar *)"#default"))
    targetNs = xmlSearchNs(node->doc, node, NULL);
    else {
    targetNs = xmlSearchNs(node->doc, node, resultPrefix);

        if (targetNs == NULL) {
       xsltTransformError(NULL, style, node,
            "Attribute 'result-prefix': There's no namespace "
        "declaration in scope for the prefix '%s'.\n",
            stylePrefix);
        goto error;
    }
    }
    /*
     *
     * Same alias for multiple different target namespace URIs:
     *  TODO: The one with the highest import precedence is used.
     *  Example:
     *  <xsl:namespace-alias stylesheet-prefix="foo"
     *                       result-prefix="bar"/>
     *
     *  <xsl:namespace-alias stylesheet-prefix="foo"
     *                       result-prefix="zar"/>
     *
     * Same target namespace URI for multiple different aliases:
     *  All alias-definitions will be used.
     *  Example:
     *  <xsl:namespace-alias stylesheet-prefix="bar"
     *                       result-prefix="foo"/>
     *
     *  <xsl:namespace-alias stylesheet-prefix="zar"
     *                       result-prefix="foo"/>
     * Cases using #default:
     *  <xsl:namespace-alias stylesheet-prefix="#default"
     *                       result-prefix="#default"/>
     *  TODO: Has this an effect at all?
     *
     *  <xsl:namespace-alias stylesheet-prefix="foo"
     *                       result-prefix="#default"/>
     *  From namespace to no namespace.
     *
     *  <xsl:namespace-alias stylesheet-prefix="#default"
     *                       result-prefix="foo"/>
     *  From no namespace to namespace.
     */
    
    
     /*
     * Store the ns-node in the alias-object.
    */
    alias = xsltNewNsAlias(XSLT_CCTXT(style));
    if (alias == NULL)
    return;
    alias->literalNs = literalNs;
    alias->targetNs = targetNs;
    XSLT_CCTXT(style)->hasNsAliases = 1;


#else /* XSLT_REFACTORED */
    const xmlChar *literalNsName;
    const xmlChar *targetNsName;
    

    if ((style == NULL) || (node == NULL))
    return;

    stylePrefix = xmlGetNsProp(node, (const xmlChar *)"stylesheet-prefix", NULL);
    if (stylePrefix == NULL) {
    xsltTransformError(NULL, style, node,
        "namespace-alias: stylesheet-prefix attribute missing\n");
    return;
    }
    resultPrefix = xmlGetNsProp(node, (const xmlChar *)"result-prefix", NULL);
    if (resultPrefix == NULL) {
    xsltTransformError(NULL, style, node,
        "namespace-alias: result-prefix attribute missing\n");
    goto error;
    }
    
    if (xmlStrEqual(stylePrefix, (const xmlChar *)"#default")) {
    literalNs = xmlSearchNs(node->doc, node, NULL);
    if (literalNs == NULL) {
        literalNsName = NULL;
    } else
        literalNsName = literalNs->href; /* Yes - set for nsAlias table */
    } else {
    literalNs = xmlSearchNs(node->doc, node, stylePrefix);
 
    if ((literalNs == NULL) || (literalNs->href == NULL)) {
        xsltTransformError(NULL, style, node,
            "namespace-alias: prefix %s not bound to any namespace\n",
                    stylePrefix);
        goto error;
    } else
        literalNsName = literalNs->href;
    }

    /*
     * When "#default" is used for result, if a default namespace has not
     * been explicitly declared the special value UNDEFINED_DEFAULT_NS is
     * put into the nsAliases table
     */
    if (xmlStrEqual(resultPrefix, (const xmlChar *)"#default")) {
    targetNs = xmlSearchNs(node->doc, node, NULL);
    if (targetNs == NULL) {
        targetNsName = UNDEFINED_DEFAULT_NS;
    } else
        targetNsName = targetNs->href;
    } else {
    targetNs = xmlSearchNs(node->doc, node, resultPrefix);

        if ((targetNs == NULL) || (targetNs->href == NULL)) {
        xsltTransformError(NULL, style, node,
            "namespace-alias: prefix %s not bound to any namespace\n",
                    resultPrefix);
        goto error;
    } else
        targetNsName = targetNs->href;
    }
    /*
     * Special case: if #default is used for
     *  the stylesheet-prefix (literal namespace) and there's no default
     *  namespace in scope, we'll use style->defaultAlias for this.
     */   
    if (literalNsName == NULL) {
        if (targetNs != NULL) {
        /*
        * BUG TODO: Is it not sufficient to have only 1 field for
        *  this, since subsequently alias declarations will
        *  overwrite this.      
        *  Example:
        *   <xsl:namespace-alias result-prefix="foo"
        *                        stylesheet-prefix="#default"/>
        *   <xsl:namespace-alias result-prefix="bar"
        *                        stylesheet-prefix="#default"/>
        *  The mapping for "foo" won't be visible anymore.
        */
            style->defaultAlias = targetNs->href;
    }
    } else {
        if (style->nsAliases == NULL)
        style->nsAliases = xmlHashCreate(10);
        if (style->nsAliases == NULL) {
        xsltTransformError(NULL, style, node,
            "namespace-alias: cannot create hash table\n");
        goto error;
        }
    xmlHashAddEntry((xmlHashTablePtr) style->nsAliases,
        literalNsName, (void *) targetNsName);
    }
#endif /* else of XSLT_REFACTORED */

error:
    if (stylePrefix != NULL)
    xmlFree(stylePrefix);
    if (resultPrefix != NULL)
    xmlFree(resultPrefix);
}

xmlNsPtr
xsltGetSpecialNamespace(xsltTransformContextPtr ctxt, xmlNodePtr invocNode,
        const xmlChar *nsName, const xmlChar *nsPrefix,
        xmlNodePtr target)
{
    xmlNsPtr ns;
    int prefixOccupied = 0;

    if ((ctxt == NULL) || (target == NULL) ||
    (target->type != XML_ELEMENT_NODE))
    return(NULL);

    /*
    * NOTE: Namespace exclusion and ns-aliasing is performed at
    *  compilation-time in the refactored code; so this need not be done
    *  here (it was in the old code).
    * NOTE: @invocNode was named @cur in the old code and was documented to
    *  be an input node; since it was only used to anchor an error report
    *  somewhere, we can safely change this to @invocNode, which now
    *  will be the XSLT instruction (also a literal result element/attribute),
    *  which was responsible for this call.
    */
    /*
    * OPTIMIZE TODO: This all could be optimized by keeping track of
    *  the ns-decls currently in-scope via a specialized context.
    */    
    if ((nsPrefix == NULL) && ((nsName == NULL) || (nsName[0] == 0))) {
    /*
    * NOTE: the "undeclaration" of the default namespace was
    * part of the logic of the old xsltGetSpecialNamespace() code,
    * so we'll keep that mechanism.
    * Related to the old code: bug #302020:
    */
    /*
    * OPTIMIZE TODO: This all could be optimized by keeping track of
    *  the ns-decls currently in-scope via a specialized context.
    */
    /*
    * Search on the result element itself.
    */
    if (target->nsDef != NULL) {
        ns = target->nsDef;
        do {
        if (ns->prefix == NULL) {
            if ((ns->href != NULL) && (ns->href[0] != 0)) {
            /*
            * Raise a namespace normalization error.
            */
            xsltTransformError(ctxt, NULL, invocNode,
                "Namespace normalization error: Cannot undeclare "
                "the default namespace, since the default namespace "
                "'%s' is already declared on the result element "
                "'%s'.\n", ns->href, target->name);
            return(NULL);
            } else {
            /*
            * The default namespace was undeclared on the
            * result element.
            */
            return(NULL);
            }
            break;
        }
        ns = ns->next;
        } while (ns != NULL);
    }   
    if ((target->parent != NULL) &&
        (target->parent->type == XML_ELEMENT_NODE))
    {
        /*
        * The parent element is in no namespace, so assume
        * that there is no default namespace in scope.
        */
        if (target->parent->ns == NULL)
        return(NULL);
        
        ns = xmlSearchNs(target->doc, target->parent,
        NULL);
        /*
        * Fine if there's no default ns is scope, or if the
        * default ns was undeclared.
        */
        if ((ns == NULL) || (ns->href == NULL) || (ns->href[0] == 0))
        return(NULL);
        
        /*
        * Undeclare the default namespace.
        */
        xmlNewNs(target, BAD_CAST "", NULL);
        /* TODO: Check result */    
        return(NULL);
    }
    return(NULL);
    }
    /*
    * Handle the XML namespace.
    * QUESTION: Is this faster than using xmlStrEqual() anyway?
    */
    if ((nsPrefix != NULL) &&
    (nsPrefix[0] == 'x') && (nsPrefix[1] == 'm') &&
    (nsPrefix[2] == 'l') && (nsPrefix[3] == 0))
    {
    return(xmlSearchNs(target->doc, target, nsPrefix));
    }
    /*
    * First: search on the result element itself.
    */
    if (target->nsDef != NULL) {
    ns = target->nsDef;
    do {
        if ((ns->prefix == NULL) == (nsPrefix == NULL)) {
        if (ns->prefix == nsPrefix) {
            if (xmlStrEqual(ns->href, nsName))
            return(ns);
            prefixOccupied = 1;
            break;
        } else if (xmlStrEqual(ns->prefix, nsPrefix)) {
            if (xmlStrEqual(ns->href, nsName))
            return(ns);
            prefixOccupied = 1;
            break;
        }
        }
        ns = ns->next;
    } while (ns != NULL);
    }
    if (prefixOccupied) {
    /*
    * If the ns-prefix is occupied by an other ns-decl on the
    * result element, then this means:
    * 1) The desired prefix is shadowed
    * 2) There's no way around changing the prefix  
    *
    * Try a desperate search for an in-scope ns-decl
    * with a matching ns-name before we use the last option,
    * which is to recreate the ns-decl with a modified prefix.
    */
    ns = xmlSearchNsByHref(target->doc, target, nsName);
    if (ns != NULL)
        return(ns);

    /*
    * Fallback to changing the prefix.
    */    
    } else if ((target->parent != NULL) &&
    (target->parent->type == XML_ELEMENT_NODE))
    {
    /*
    * Try to find a matching ns-decl in the ancestor-axis.
    *
    * Check the common case: The parent element of the current
    * result element is in the same namespace (with an equal ns-prefix).
    */     
    if ((target->parent->ns != NULL) &&
        ((target->parent->ns->prefix != NULL) == (nsPrefix != NULL)))
    {
        ns = target->parent->ns;
        
        if (nsPrefix == NULL) {
        if (xmlStrEqual(ns->href, nsName))
            return(ns);
        } else if (xmlStrEqual(ns->prefix, nsPrefix) &&
        xmlStrEqual(ns->href, nsName))
        {
        return(ns);
        }
    }
    /*
    * Lookup the remaining in-scope namespaces.
    */    
    ns = xmlSearchNs(target->doc, target->parent, nsPrefix);
    if (ns != NULL) {
        if (xmlStrEqual(ns->href, nsName))
        return(ns);     
        /*
        * Now check for a nasty case: We need to ensure that the new
        * ns-decl won't shadow a prefix in-use by an existing attribute.
        * <foo xmlns:a="urn:test:a">
        *   <bar a:a="val-a">
        *     <xsl:attribute xmlns:a="urn:test:b" name="a:b">
        *        val-b</xsl:attribute>
        *   </bar>
        * </foo>
        */
        if (target->properties) {
        xmlAttrPtr attr = target->properties;
        do {
            if ((attr->ns) &&
            xmlStrEqual(attr->ns->prefix, nsPrefix))
            {
            /*
            * Bad, this prefix is already in use.
            * Since we'll change the prefix anyway, try
            * a search for a matching ns-decl based on the
            * namespace name.
            */
            ns = xmlSearchNsByHref(target->doc, target, nsName);
            if (ns != NULL)
                return(ns);
            goto declare_new_prefix;
            }
            attr = attr->next;
        } while (attr != NULL);
        }
    } else {
        /*
        * Either no matching ns-prefix was found or the namespace is
        * shadowed.
        * Create a new ns-decl on the current result element.
        *
        * Hmm, we could also try to reuse an in-scope
        * namespace with a matching ns-name but a different
        * ns-prefix.
        * What has higher priority?
        *  1) If keeping the prefix: create a new ns-decl.
        *  2) If reusal: first lookup ns-names; then fallback
        *     to creation of a new ns-decl.
        * REVISIT: this currently uses case 1) although
        *  the old way was use xmlSearchNsByHref() and to let change
        *  the prefix.
        */
#if 0
        ns = xmlSearchNsByHref(target->doc, target, nsName);
        if (ns != NULL)
        return(ns);
#endif
    }
    /*
    * Create the ns-decl on the current result element.
    */
    ns = xmlNewNs(target, nsName, nsPrefix);
    /* TODO: check errors */
    return(ns);
    } else {
    /*
    * This is either the root of the tree or something weird is going on.
    */
    ns = xmlNewNs(target, nsName, nsPrefix);
    /* TODO: Check result */
    return(ns);
    }

declare_new_prefix:
    /*
    * Fallback: we need to generate a new prefix and declare the namespace
    * on the result element.
    */
    {
    xmlChar pref[30];
    int counter = 1;

    if (nsPrefix == NULL) {
        nsPrefix = "ns";
    }

    do {
        snprintf((char *) pref, 30, "%s_%d", nsPrefix, counter++);
        ns = xmlSearchNs(target->doc, target, BAD_CAST pref);
        if (counter > 1000) {
        xsltTransformError(ctxt, NULL, invocNode,
            "Internal error in xsltAcquireResultInScopeNs(): "
            "Failed to compute a unique ns-prefix for the "
            "generated element");
        return(NULL);
        }
    } while (ns != NULL);
    ns = xmlNewNs(target, nsName, BAD_CAST pref);
    /* TODO: Check result */
    return(ns);
    }
    return(NULL);
}

xmlNsPtr
xsltGetNamespace(xsltTransformContextPtr ctxt, xmlNodePtr cur, xmlNsPtr ns,
             xmlNodePtr out)
{    
    
    if (ns == NULL)
    return(NULL);

#ifdef XSLT_REFACTORED
    /*
    * Namespace exclusion and ns-aliasing is performed at
    * compilation-time in the refactored code.
    * Additionally, aliasing is not intended for non Literal
    * Result Elements.
    */
    return(xsltGetSpecialNamespace(ctxt, cur, ns->href, ns->prefix, out));
#else
    {
    xsltStylesheetPtr style;
    const xmlChar *URI = NULL; /* the replacement URI */

    if ((ctxt == NULL) || (cur == NULL) || (out == NULL))
        return(NULL);

    style = ctxt->style;
    while (style != NULL) {
        if (style->nsAliases != NULL)
        URI = (const xmlChar *) 
        xmlHashLookup(style->nsAliases, ns->href);
        if (URI != NULL)
        break;
        
        style = xsltNextImport(style);
    }
    
    
    if (URI == UNDEFINED_DEFAULT_NS) {
        return(xsltGetSpecialNamespace(ctxt, cur, NULL, NULL, out));
#if 0
        /*
        * TODO: Removed, since wrong. If there was no default
        * namespace in the stylesheet then this must resolve to
        * the NULL namespace.
        */
        xmlNsPtr dflt;      
        dflt = xmlSearchNs(cur->doc, cur, NULL);
        if (dflt != NULL)
        URI = dflt->href;
        else
        return NULL;
#endif
    } else if (URI == NULL)
        URI = ns->href;

    return(xsltGetSpecialNamespace(ctxt, cur, URI, ns->prefix, out));
    }
#endif
}

xmlNsPtr
xsltGetPlainNamespace(xsltTransformContextPtr ctxt, xmlNodePtr cur,
                      xmlNsPtr ns, xmlNodePtr out)
{    
    return(xsltGetNamespace(ctxt, cur, ns, out));
}

xmlNsPtr
xsltCopyNamespaceList(xsltTransformContextPtr ctxt, xmlNodePtr node,
                  xmlNsPtr cur) {
    xmlNsPtr ret = NULL, tmp;
    xmlNsPtr p = NULL,q;    

    if (cur == NULL)
    return(NULL);
    if (cur->type != XML_NAMESPACE_DECL)
    return(NULL);

    /*
     * One can add namespaces only on element nodes
     */
    if ((node != NULL) && (node->type != XML_ELEMENT_NODE))
    node = NULL;

    while (cur != NULL) {
    if (cur->type != XML_NAMESPACE_DECL)
        break;

    /*
     * Avoid duplicating namespace declarations in the tree if
     * a matching declaration is in scope.
     */
    if (node != NULL) {
        if ((node->ns != NULL) &&
        (xmlStrEqual(node->ns->prefix, cur->prefix)) &&
            (xmlStrEqual(node->ns->href, cur->href))) {
        cur = cur->next;
        continue;
        }
        tmp = xmlSearchNs(node->doc, node, cur->prefix);
        if ((tmp != NULL) && (xmlStrEqual(tmp->href, cur->href))) {
        cur = cur->next;
        continue;
        }
    }
#ifdef XSLT_REFACTORED
    /*
    * Namespace exclusion and ns-aliasing is performed at
    * compilation-time in the refactored code.
    */
    q = xmlNewNs(node, cur->href, cur->prefix);
    if (p == NULL) {
        ret = p = q;
    } else {
        p->next = q;
        p = q;
    }
#else
    /*
    * TODO: Remove this if the refactored code gets enabled.
    */
    if (!xmlStrEqual(cur->href, XSLT_NAMESPACE)) {
        const xmlChar *URI;
        /* TODO apply cascading */
        URI = (const xmlChar *) xmlHashLookup(ctxt->style->nsAliases,
                                          cur->href);
        if (URI == UNDEFINED_DEFAULT_NS)
            continue;
        if (URI != NULL) {
        q = xmlNewNs(node, URI, cur->prefix);
        } else {
        q = xmlNewNs(node, cur->href, cur->prefix);
        }
        if (p == NULL) {
        ret = p = q;
        } else {
        p->next = q;
        p = q;
        }
    }
#endif
    cur = cur->next;
    }
    return(ret);
}

xmlNsPtr
xsltCopyNamespace(xsltTransformContextPtr ctxt ATTRIBUTE_UNUSED,
          xmlNodePtr elem, xmlNsPtr ns)
{    
    if ((ns == NULL) || (ns->type != XML_NAMESPACE_DECL))
    return(NULL);
    /*
     * One can add namespaces only on element nodes
     */
    if ((elem != NULL) && (elem->type != XML_ELEMENT_NODE))
    return(xmlNewNs(NULL, ns->href, ns->prefix));
    else
    return(xmlNewNs(elem, ns->href, ns->prefix));
}


void
xsltFreeNamespaceAliasHashes(xsltStylesheetPtr style) {
    if (style->nsAliases != NULL)
    xmlHashFree((xmlHashTablePtr) style->nsAliases, NULL);
    style->nsAliases = NULL;
}