xml.c

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/*
 * Copyright 2004-2024 the Pacemaker project contributors
 *
 * The version control history for this file may have further details.
 *
 * This source code is licensed under the GNU Lesser General Public License
 * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
 */

#include <crm_internal.h>

#include <stdarg.h>
#include <stdint.h>                     // uint32_t
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>                   // stat(), S_ISREG, etc.
#include <sys/types.h>

#include <glib.h>                       // gboolean, GString
#include <libxml/parser.h>              // xmlCleanupParser()
#include <libxml/tree.h>                // xmlNode, etc.
#include <libxml/xmlstring.h>           // xmlGetUTF8Char()

#include <crm/crm.h>
#include <crm/common/xml.h>
#include <crm/common/xml_internal.h>    // PCMK__XML_LOG_BASE, etc.
#include "crmcommon_private.h"

#define XML_VERSION ((pcmkXmlStr) "1.0")

bool
pcmk__xml_tree_foreach(xmlNode *xml, bool (*fn)(xmlNode *, void *),
                       void *user_data)
{
    if (xml == NULL) {
        return true;
    }

    if (!fn(xml, user_data)) {
        return false;
    }

    for (xml = pcmk__xml_first_child(xml); xml != NULL;
         xml = pcmk__xml_next(xml)) {

        if (!pcmk__xml_tree_foreach(xml, fn, user_data)) {
            return false;
        }
    }
    return true;
}

bool
pcmk__tracking_xml_changes(xmlNode *xml, bool lazy)
{
    if(xml == NULL || xml->doc == NULL || xml->doc->_private == NULL) {
        return FALSE;
    } else if (!pcmk_is_set(((xml_doc_private_t *)xml->doc->_private)->flags,
                            pcmk__xf_tracking)) {
        return FALSE;
    } else if (lazy && !pcmk_is_set(((xml_doc_private_t *)xml->doc->_private)->flags,
                                    pcmk__xf_lazy)) {
        return FALSE;
    }
    return TRUE;
}

void
pcmk__xml_set_parent_flags(xmlNode *xml, uint64_t flags)
{
    for (; xml != NULL; xml = xml->parent) {
        xml_node_private_t *nodepriv = xml->_private;

        if (nodepriv != NULL) {
            pcmk__set_xml_flags(nodepriv, flags);
        }
    }
}

void
pcmk__set_xml_doc_flag(xmlNode *xml, enum xml_private_flags flag)
{
    if (xml != NULL) {
        xml_doc_private_t *docpriv = xml->doc->_private;

        pcmk__set_xml_flags(docpriv, flag);
    }
}

// Mark document, element, and all element's parents as changed
void
pcmk__mark_xml_node_dirty(xmlNode *xml)
{
    pcmk__set_xml_doc_flag(xml, pcmk__xf_dirty);
    pcmk__xml_set_parent_flags(xml, pcmk__xf_dirty);
}

bool
pcmk__xml_reset_node_flags(xmlNode *xml, void *user_data)
{
    xml_node_private_t *nodepriv = xml->_private;

    if (nodepriv != NULL) {
        nodepriv->flags = pcmk__xf_none;
    }
    return true;
}

static bool
mark_xml_dirty_created(xmlNode *xml, void *user_data)
{
    xml_node_private_t *nodepriv = xml->_private;

    if (nodepriv != NULL) {
        pcmk__set_xml_flags(nodepriv, pcmk__xf_dirty|pcmk__xf_created);
    }
    return true;
}

static void
mark_xml_tree_dirty_created(xmlNode *xml)
{
    pcmk__assert(xml != NULL);

    if (!pcmk__tracking_xml_changes(xml, false)) {
        // Tracking is disabled for entire document
        return;
    }

    // Mark all parents and document dirty
    pcmk__mark_xml_node_dirty(xml);

    pcmk__xml_tree_foreach(xml, mark_xml_dirty_created, NULL);
}

// Free an XML object previously marked as deleted
static void
free_deleted_object(void *data)
{
    if(data) {
        pcmk__deleted_xml_t *deleted_obj = data;

        g_free(deleted_obj->path);
        free(deleted_obj);
    }
}

// Free and NULL user, ACLs, and deleted objects in an XML node's private data
static void
reset_xml_private_data(xml_doc_private_t *docpriv)
{
    if (docpriv != NULL) {
        pcmk__assert(docpriv->check == PCMK__XML_DOC_PRIVATE_MAGIC);

        free(docpriv->user);
        docpriv->user = NULL;

        if (docpriv->acls != NULL) {
            pcmk__free_acls(docpriv->acls);
            docpriv->acls = NULL;
        }

        if(docpriv->deleted_objs) {
            g_list_free_full(docpriv->deleted_objs, free_deleted_object);
            docpriv->deleted_objs = NULL;
        }
    }
}

static bool
new_private_data(xmlNode *node, void *user_data)
{
    CRM_CHECK(node != NULL, return true);

    if (node->_private != NULL) {
        return true;
    }

    switch (node->type) {
        case XML_DOCUMENT_NODE:
            {
                xml_doc_private_t *docpriv =
                    pcmk__assert_alloc(1, sizeof(xml_doc_private_t));

                docpriv->check = PCMK__XML_DOC_PRIVATE_MAGIC;
                node->_private = docpriv;
                pcmk__set_xml_flags(docpriv, pcmk__xf_dirty|pcmk__xf_created);
            }
            break;

        case XML_ELEMENT_NODE:
        case XML_ATTRIBUTE_NODE:
        case XML_COMMENT_NODE:
            {
                xml_node_private_t *nodepriv =
                    pcmk__assert_alloc(1, sizeof(xml_node_private_t));

                nodepriv->check = PCMK__XML_NODE_PRIVATE_MAGIC;
                node->_private = nodepriv;
                pcmk__set_xml_flags(nodepriv, pcmk__xf_dirty|pcmk__xf_created);

                for (xmlAttr *iter = pcmk__xe_first_attr(node); iter != NULL;
                     iter = iter->next) {

                    new_private_data((xmlNode *) iter, user_data);
                }
            }
            break;

        case XML_TEXT_NODE:
        case XML_DTD_NODE:
        case XML_CDATA_SECTION_NODE:
            return true;

        default:
            CRM_LOG_ASSERT(node->type == XML_ELEMENT_NODE);
            return true;
    }

    if (pcmk__tracking_xml_changes(node, false)) {
        pcmk__mark_xml_node_dirty(node);
    }
    return true;
}

static bool
free_private_data(xmlNode *node, void *user_data)
{
    CRM_CHECK(node != NULL, return true);

    if (node->_private == NULL) {
        return true;
    }

    if (node->type == XML_DOCUMENT_NODE) {
        reset_xml_private_data((xml_doc_private_t *) node->_private);

    } else {
        xml_node_private_t *nodepriv = node->_private;

        pcmk__assert(nodepriv->check == PCMK__XML_NODE_PRIVATE_MAGIC);

        for (xmlAttr *iter = pcmk__xe_first_attr(node); iter != NULL;
             iter = iter->next) {

            free_private_data((xmlNode *) iter, user_data);
        }
    }
    free(node->_private);
    node->_private = NULL;
    return true;
}

void
pcmk__xml_new_private_data(xmlNode *xml)
{
    pcmk__xml_tree_foreach(xml, new_private_data, NULL);
}

void
pcmk__xml_free_private_data(xmlNode *xml)
{
    pcmk__xml_tree_foreach(xml, free_private_data, NULL);
}

void
xml_track_changes(xmlNode * xml, const char *user, xmlNode *acl_source, bool enforce_acls) 
{
    xml_accept_changes(xml);
    crm_trace("Tracking changes%s to %p", enforce_acls?" with ACLs":"", xml);
    pcmk__set_xml_doc_flag(xml, pcmk__xf_tracking);
    if(enforce_acls) {
        if(acl_source == NULL) {
            acl_source = xml;
        }
        pcmk__set_xml_doc_flag(xml, pcmk__xf_acl_enabled);
        pcmk__unpack_acl(acl_source, xml, user);
        pcmk__apply_acl(xml);
    }
}

bool xml_tracking_changes(xmlNode * xml)
{
    return (xml != NULL) && (xml->doc != NULL) && (xml->doc->_private != NULL)
           && pcmk_is_set(((xml_doc_private_t *)(xml->doc->_private))->flags,
                          pcmk__xf_tracking);
}

bool xml_document_dirty(xmlNode *xml) 
{
    return (xml != NULL) && (xml->doc != NULL) && (xml->doc->_private != NULL)
           && pcmk_is_set(((xml_doc_private_t *)(xml->doc->_private))->flags,
                          pcmk__xf_dirty);
}

int
pcmk__xml_position(const xmlNode *xml, enum xml_private_flags ignore_if_set)
{
    int position = 0;

    for (const xmlNode *cIter = xml; cIter->prev; cIter = cIter->prev) {
        xml_node_private_t *nodepriv = ((xmlNode*)cIter->prev)->_private;

        if (!pcmk_is_set(nodepriv->flags, ignore_if_set)) {
            position++;
        }
    }

    return position;
}

static bool
accept_attr_deletions(xmlNode *xml, void *user_data)
{
    pcmk__xml_reset_node_flags(xml, NULL);
    pcmk__xe_remove_matching_attrs(xml, pcmk__marked_as_deleted, NULL);
    return true;
}

xmlNode *
pcmk__xml_match(const xmlNode *haystack, const xmlNode *needle, bool exact)
{
    CRM_CHECK(needle != NULL, return NULL);

    if (needle->type == XML_COMMENT_NODE) {
        return pcmk__xc_match(haystack, needle, exact);

    } else {
        const char *id = pcmk__xe_id(needle);
        const char *attr = (id == NULL)? NULL : PCMK_XA_ID;

        return pcmk__xe_first_child(haystack, (const char *) needle->name, attr,
                                    id);
    }
}

void
xml_accept_changes(xmlNode * xml)
{
    xmlNode *top = NULL;
    xml_doc_private_t *docpriv = NULL;

    if(xml == NULL) {
        return;
    }

    crm_trace("Accepting changes to %p", xml);
    docpriv = xml->doc->_private;
    top = xmlDocGetRootElement(xml->doc);

    reset_xml_private_data(xml->doc->_private);

    if (!pcmk_is_set(docpriv->flags, pcmk__xf_dirty)) {
        docpriv->flags = pcmk__xf_none;
        return;
    }

    docpriv->flags = pcmk__xf_none;
    pcmk__xml_tree_foreach(top, accept_attr_deletions, NULL);
}

xmlDoc *
pcmk__xml_new_doc(void)
{
    xmlDoc *doc = xmlNewDoc(XML_VERSION);

    pcmk__mem_assert(doc);
    pcmk__xml_new_private_data((xmlNode *) doc);
    return doc;
}

void
pcmk__xml_free_doc(xmlDoc *doc)
{
    if (doc != NULL) {
        pcmk__xml_free_private_data((xmlNode *) doc);
        xmlFreeDoc(doc);
    }
}

bool
pcmk__xml_is_name_start_char(const char *utf8, int *len)
{
    int c = 0;
    int local_len = 0;

    if (len == NULL) {
        len = &local_len;
    }

    /* xmlGetUTF8Char() abuses the len argument. At call time, it must be set to
     * "the minimum number of bytes present in the sequence... to assure the
     * next character is completely contained within the sequence." It's similar
     * to the "n" in the strn*() functions. However, this doesn't make any sense
     * for null-terminated strings, and there's no value that indicates "keep
     * going until '\0'." So we set it to 4, the max number of bytes in a UTF-8
     * character.
     *
     * At return, it's set to the actual number of bytes in the char, or 0 on
     * error.
     */
    *len = 4;

    // Note: xmlGetUTF8Char() assumes a 32-bit int
    c = xmlGetUTF8Char((pcmkXmlStr) utf8, len);
    if (c < 0) {
        GString *buf = g_string_sized_new(32);

        for (int i = 0; (i < 4) && (utf8[i] != '\0'); i++) {
            g_string_append_printf(buf, " 0x%.2X", utf8[i]);
        }
        crm_info("Invalid UTF-8 character (bytes:%s)",
                 (pcmk__str_empty(buf->str)? " <none>" : buf->str));
        g_string_free(buf, TRUE);
        return false;
    }

    return (c == '_')
           || (c == ':')
           || ((c >= 'a') && (c <= 'z'))
           || ((c >= 'A') && (c <= 'Z'))
           || ((c >= 0xC0) && (c <= 0xD6))
           || ((c >= 0xD8) && (c <= 0xF6))
           || ((c >= 0xF8) && (c <= 0x2FF))
           || ((c >= 0x370) && (c <= 0x37D))
           || ((c >= 0x37F) && (c <= 0x1FFF))
           || ((c >= 0x200C) && (c <= 0x200D))
           || ((c >= 0x2070) && (c <= 0x218F))
           || ((c >= 0x2C00) && (c <= 0x2FEF))
           || ((c >= 0x3001) && (c <= 0xD7FF))
           || ((c >= 0xF900) && (c <= 0xFDCF))
           || ((c >= 0xFDF0) && (c <= 0xFFFD))
           || ((c >= 0x10000) && (c <= 0xEFFFF));
}

bool
pcmk__xml_is_name_char(const char *utf8, int *len)
{
    int c = 0;
    int local_len = 0;

    if (len == NULL) {
        len = &local_len;
    }

    // See comment regarding len in pcmk__xml_is_name_start_char()
    *len = 4;

    // Note: xmlGetUTF8Char() assumes a 32-bit int
    c = xmlGetUTF8Char((pcmkXmlStr) utf8, len);
    if (c < 0) {
        GString *buf = g_string_sized_new(32);

        for (int i = 0; (i < 4) && (utf8[i] != '\0'); i++) {
            g_string_append_printf(buf, " 0x%.2X", utf8[i]);
        }
        crm_info("Invalid UTF-8 character (bytes:%s)",
                 (pcmk__str_empty(buf->str)? " <none>" : buf->str));
        g_string_free(buf, TRUE);
        return false;
    }

    return ((c >= 'a') && (c <= 'z'))
           || ((c >= 'A') && (c <= 'Z'))
           || ((c >= '0') && (c <= '9'))
           || (c == '_')
           || (c == ':')
           || (c == '-')
           || (c == '.')
           || (c == 0xB7)
           || ((c >= 0xC0) && (c <= 0xD6))
           || ((c >= 0xD8) && (c <= 0xF6))
           || ((c >= 0xF8) && (c <= 0x2FF))
           || ((c >= 0x300) && (c <= 0x36F))
           || ((c >= 0x370) && (c <= 0x37D))
           || ((c >= 0x37F) && (c <= 0x1FFF))
           || ((c >= 0x200C) && (c <= 0x200D))
           || ((c >= 0x203F) && (c <= 0x2040))
           || ((c >= 0x2070) && (c <= 0x218F))
           || ((c >= 0x2C00) && (c <= 0x2FEF))
           || ((c >= 0x3001) && (c <= 0xD7FF))
           || ((c >= 0xF900) && (c <= 0xFDCF))
           || ((c >= 0xFDF0) && (c <= 0xFFFD))
           || ((c >= 0x10000) && (c <= 0xEFFFF));
}

void
pcmk__xml_sanitize_id(char *id)
{
    bool valid = true;
    int len = 0;

    // If id is empty or NULL, there's no way to make it a valid XML ID
    pcmk__assert(!pcmk__str_empty(id));

    /* @TODO Suppose there are two strings and each has an invalid ID character
     * in the same position. The strings are otherwise identical. Both strings
     * will be sanitized to the same valid ID, which is incorrect.
     *
     * The caller is responsible for ensuring the sanitized ID does not already
     * exist in a given XML document before using it, if uniqueness is desired.
     */
    valid = pcmk__xml_is_name_start_char(id, &len);
    CRM_CHECK(len > 0, return); // UTF-8 encoding error
    if (!valid) {
        *id = '_';
        for (int i = 1; i < len; i++) {
            id[i] = '.';
        }
    }

    for (id += len; *id != '\0'; id += len) {
        valid = pcmk__xml_is_name_char(id, &len);
        CRM_CHECK(len > 0, return); // UTF-8 encoding error
        if (!valid) {
            for (int i = 0; i < len; i++) {
                id[i] = '.';
            }
        }
    }
}

void
pcmk__xml_free_node(xmlNode *xml)
{
    pcmk__xml_free_private_data(xml);
    xmlUnlinkNode(xml);
    xmlFreeNode(xml);
}

static void
free_xml_with_position(xmlNode *node, int position)
{
    xmlDoc *doc = NULL;
    xml_node_private_t *nodepriv = NULL;

    if (node == NULL) {
        return;
    }
    doc = node->doc;
    nodepriv = node->_private;

    if ((doc != NULL) && (xmlDocGetRootElement(doc) == node)) {
        /* @TODO Should we check ACLs first? Otherwise it seems like we could
         * free the root element without write permission.
         */
        pcmk__xml_free_doc(doc);
        return;
    }

    if (!pcmk__check_acl(node, NULL, pcmk__xf_acl_write)) {
        GString *xpath = NULL;

        pcmk__if_tracing({}, return);
        xpath = pcmk__element_xpath(node);
        qb_log_from_external_source(__func__, __FILE__,
                                    "Cannot remove %s %x", LOG_TRACE,
                                    __LINE__, 0, xpath->str, nodepriv->flags);
        g_string_free(xpath, TRUE);
        return;
    }

    if ((doc != NULL) && pcmk__tracking_xml_changes(node, false)
        && !pcmk_is_set(nodepriv->flags, pcmk__xf_created)) {

        xml_doc_private_t *docpriv = doc->_private;
        GString *xpath = pcmk__element_xpath(node);

        if (xpath != NULL) {
            pcmk__deleted_xml_t *deleted_obj = NULL;

            crm_trace("Deleting %s %p from %p", xpath->str, node, doc);

            deleted_obj = pcmk__assert_alloc(1, sizeof(pcmk__deleted_xml_t));
            deleted_obj->path = g_string_free(xpath, FALSE);
            deleted_obj->position = -1;

            // Record the position only for XML comments for now
            if (node->type == XML_COMMENT_NODE) {
                if (position >= 0) {
                    deleted_obj->position = position;

                } else {
                    deleted_obj->position = pcmk__xml_position(node,
                                                               pcmk__xf_skip);
                }
            }

            docpriv->deleted_objs = g_list_append(docpriv->deleted_objs,
                                                  deleted_obj);
            pcmk__set_xml_doc_flag(node, pcmk__xf_dirty);
        }
    }
    pcmk__xml_free_node(node);
}

void
pcmk__xml_free(xmlNode *xml)
{
    free_xml_with_position(xml, -1);
}

xmlNode *
pcmk__xml_copy(xmlNode *parent, xmlNode *src)
{
    xmlNode *copy = NULL;

    if (src == NULL) {
        return NULL;
    }

    if (parent == NULL) {
        xmlDoc *doc = NULL;

        // The copy will be the root element of a new document
        pcmk__assert(src->type == XML_ELEMENT_NODE);

        doc = pcmk__xml_new_doc();
        copy = xmlDocCopyNode(src, doc, 1);
        pcmk__mem_assert(copy);

        xmlDocSetRootElement(doc, copy);

    } else {
        copy = xmlDocCopyNode(src, parent->doc, 1);
        pcmk__mem_assert(copy);

        xmlAddChild(parent, copy);
    }

    pcmk__xml_new_private_data(copy);
    return copy;
}

void
pcmk__strip_xml_text(xmlNode *xml)
{
    xmlNode *iter = xml->children;

    while (iter) {
        xmlNode *next = iter->next;

        switch (iter->type) {
            case XML_TEXT_NODE:
                pcmk__xml_free_node(iter);
                break;

            case XML_ELEMENT_NODE:
                /* Search it */
                pcmk__strip_xml_text(iter);
                break;

            default:
                /* Leave it */
                break;
        }

        iter = next;
    }
}

bool
pcmk__xml_needs_escape(const char *text, enum pcmk__xml_escape_type type)
{
    if (text == NULL) {
        return false;
    }

    while (*text != '\0') {
        switch (type) {
            case pcmk__xml_escape_text:
                switch (*text) {
                    case '<':
                    case '>':
                    case '&':
                        return true;
                    case '\n':
                    case '\t':
                        break;
                    default:
                        if (g_ascii_iscntrl(*text)) {
                            return true;
                        }
                        break;
                }
                break;

            case pcmk__xml_escape_attr:
                switch (*text) {
                    case '<':
                    case '>':
                    case '&':
                    case '"':
                        return true;
                    default:
                        if (g_ascii_iscntrl(*text)) {
                            return true;
                        }
                        break;
                }
                break;

            case pcmk__xml_escape_attr_pretty:
                switch (*text) {
                    case '\n':
                    case '\r':
                    case '\t':
                    case '"':
                        return true;
                    default:
                        break;
                }
                break;

            default:    // Invalid enum value
                pcmk__assert(false);
                break;
        }

        text = g_utf8_next_char(text);
    }
    return false;
}

gchar *
pcmk__xml_escape(const char *text, enum pcmk__xml_escape_type type)
{
    GString *copy = NULL;

    if (text == NULL) {
        return NULL;
    }
    copy = g_string_sized_new(strlen(text));

    while (*text != '\0') {
        // Don't escape any non-ASCII characters
        if ((*text & 0x80) != 0) {
            size_t bytes = g_utf8_next_char(text) - text;

            g_string_append_len(copy, text, bytes);
            text += bytes;
            continue;
        }

        switch (type) {
            case pcmk__xml_escape_text:
                switch (*text) {
                    case '<':
                        g_string_append(copy, PCMK__XML_ENTITY_LT);
                        break;
                    case '>':
                        g_string_append(copy, PCMK__XML_ENTITY_GT);
                        break;
                    case '&':
                        g_string_append(copy, PCMK__XML_ENTITY_AMP);
                        break;
                    case '\n':
                    case '\t':
                        g_string_append_c(copy, *text);
                        break;
                    default:
                        if (g_ascii_iscntrl(*text)) {
                            g_string_append_printf(copy, "&#x%.2X;", *text);
                        } else {
                            g_string_append_c(copy, *text);
                        }
                        break;
                }
                break;

            case pcmk__xml_escape_attr:
                switch (*text) {
                    case '<':
                        g_string_append(copy, PCMK__XML_ENTITY_LT);
                        break;
                    case '>':
                        g_string_append(copy, PCMK__XML_ENTITY_GT);
                        break;
                    case '&':
                        g_string_append(copy, PCMK__XML_ENTITY_AMP);
                        break;
                    case '"':
                        g_string_append(copy, PCMK__XML_ENTITY_QUOT);
                        break;
                    default:
                        if (g_ascii_iscntrl(*text)) {
                            g_string_append_printf(copy, "&#x%.2X;", *text);
                        } else {
                            g_string_append_c(copy, *text);
                        }
                        break;
                }
                break;

            case pcmk__xml_escape_attr_pretty:
                switch (*text) {
                    case '"':
                        g_string_append(copy, "\\\"");
                        break;
                    case '\n':
                        g_string_append(copy, "\\n");
                        break;
                    case '\r':
                        g_string_append(copy, "\\r");
                        break;
                    case '\t':
                        g_string_append(copy, "\\t");
                        break;
                    default:
                        g_string_append_c(copy, *text);
                        break;
                }
                break;

            default:    // Invalid enum value
                pcmk__assert(false);
                break;
        }

        text = g_utf8_next_char(text);
    }
    return g_string_free(copy, FALSE);
}

static void
set_attrs_flag(xmlNode *xml, enum xml_private_flags flag)
{
    for (xmlAttr *attr = pcmk__xe_first_attr(xml); attr; attr = attr->next) {
        pcmk__set_xml_flags((xml_node_private_t *) (attr->_private), flag);
    }
}

static void
mark_attr_deleted(xmlNode *new_xml, const char *element, const char *attr_name,
                  const char *old_value)
{
    xml_doc_private_t *docpriv = new_xml->doc->_private;
    xmlAttr *attr = NULL;
    xml_node_private_t *nodepriv;

    /* Restore the old value (without setting dirty flag recursively upwards or
     * checking ACLs)
     */
    pcmk__clear_xml_flags(docpriv, pcmk__xf_tracking);
    crm_xml_add(new_xml, attr_name, old_value);
    pcmk__set_xml_flags(docpriv, pcmk__xf_tracking);

    // Reset flags (so the attribute doesn't appear as newly created)
    attr = xmlHasProp(new_xml, (pcmkXmlStr) attr_name);
    nodepriv = attr->_private;
    nodepriv->flags = 0;

    // Check ACLs and mark restored value for later removal
    pcmk__xa_remove(attr, false);

    crm_trace("XML attribute %s=%s was removed from %s",
              attr_name, old_value, element);
}

/*
 * \internal
 * \brief Check ACLs for a changed XML attribute
 */
static void
mark_attr_changed(xmlNode *new_xml, const char *element, const char *attr_name,
                  const char *old_value)
{
    xml_doc_private_t *docpriv = new_xml->doc->_private;
    char *vcopy = crm_element_value_copy(new_xml, attr_name);

    crm_trace("XML attribute %s was changed from '%s' to '%s' in %s",
              attr_name, old_value, vcopy, element);

    // Restore the original value (without checking ACLs)
    pcmk__clear_xml_flags(docpriv, pcmk__xf_tracking);
    crm_xml_add(new_xml, attr_name, old_value);
    pcmk__set_xml_flags(docpriv, pcmk__xf_tracking);

    // Change it back to the new value, to check ACLs
    crm_xml_add(new_xml, attr_name, vcopy);
    free(vcopy);
}

static void
mark_attr_moved(xmlNode *new_xml, const char *element, xmlAttr *old_attr,
                xmlAttr *new_attr, int p_old, int p_new)
{
    xml_node_private_t *nodepriv = new_attr->_private;

    crm_trace("XML attribute %s moved from position %d to %d in %s",
              old_attr->name, p_old, p_new, element);

    // Mark document, element, and all element's parents as changed
    pcmk__mark_xml_node_dirty(new_xml);

    // Mark attribute as changed
    pcmk__set_xml_flags(nodepriv, pcmk__xf_dirty|pcmk__xf_moved);

    nodepriv = (p_old > p_new)? old_attr->_private : new_attr->_private;
    pcmk__set_xml_flags(nodepriv, pcmk__xf_skip);
}

static void
xml_diff_old_attrs(xmlNode *old_xml, xmlNode *new_xml)
{
    xmlAttr *attr_iter = pcmk__xe_first_attr(old_xml);

    while (attr_iter != NULL) {
        const char *name = (const char *) attr_iter->name;
        xmlAttr *old_attr = attr_iter;
        xmlAttr *new_attr = xmlHasProp(new_xml, attr_iter->name);
        const char *old_value = pcmk__xml_attr_value(attr_iter);

        attr_iter = attr_iter->next;
        if (new_attr == NULL) {
            mark_attr_deleted(new_xml, (const char *) old_xml->name, name,
                              old_value);

        } else {
            xml_node_private_t *nodepriv = new_attr->_private;
            int new_pos = pcmk__xml_position((xmlNode*) new_attr,
                                             pcmk__xf_skip);
            int old_pos = pcmk__xml_position((xmlNode*) old_attr,
                                             pcmk__xf_skip);
            const char *new_value = crm_element_value(new_xml, name);

            // This attribute isn't new
            pcmk__clear_xml_flags(nodepriv, pcmk__xf_created);

            if (strcmp(new_value, old_value) != 0) {
                mark_attr_changed(new_xml, (const char *) old_xml->name, name,
                                  old_value);

            } else if ((old_pos != new_pos)
                       && !pcmk__tracking_xml_changes(new_xml, TRUE)) {
                mark_attr_moved(new_xml, (const char *) old_xml->name,
                                old_attr, new_attr, old_pos, new_pos);
            }
        }
    }
}

static void
mark_created_attrs(xmlNode *new_xml)
{
    xmlAttr *attr_iter = pcmk__xe_first_attr(new_xml);

    while (attr_iter != NULL) {
        xmlAttr *new_attr = attr_iter;
        xml_node_private_t *nodepriv = attr_iter->_private;

        attr_iter = attr_iter->next;
        if (pcmk_is_set(nodepriv->flags, pcmk__xf_created)) {
            const char *attr_name = (const char *) new_attr->name;

            crm_trace("Created new attribute %s=%s in %s",
                      attr_name, pcmk__xml_attr_value(new_attr),
                      new_xml->name);

            /* Check ACLs (we can't use the remove-then-create trick because it
             * would modify the attribute position).
             */
            if (pcmk__check_acl(new_xml, attr_name, pcmk__xf_acl_write)) {
                pcmk__mark_xml_attr_dirty(new_attr);
            } else {
                // Creation was not allowed, so remove the attribute
                pcmk__xa_remove(new_attr, true);
            }
        }
    }
}

static void
xml_diff_attrs(xmlNode *old_xml, xmlNode *new_xml)
{
    set_attrs_flag(new_xml, pcmk__xf_created); // cleared later if not really new
    xml_diff_old_attrs(old_xml, new_xml);
    mark_created_attrs(new_xml);
}

static void
mark_child_deleted(xmlNode *old_child, xmlNode *new_parent)
{
    // Re-create the child element so we can check ACLs
    xmlNode *candidate = pcmk__xml_copy(new_parent, old_child);

    // Clear flags on new child and its children
    pcmk__xml_tree_foreach(candidate, pcmk__xml_reset_node_flags, NULL);

    // Check whether ACLs allow the deletion
    pcmk__apply_acl(xmlDocGetRootElement(candidate->doc));

    // Remove the child again (which will track it in document's deleted_objs)
    free_xml_with_position(candidate,
                           pcmk__xml_position(old_child, pcmk__xf_skip));

    if (pcmk__xml_match(new_parent, old_child, true) == NULL) {
        pcmk__set_xml_flags((xml_node_private_t *) (old_child->_private),
                            pcmk__xf_skip);
    }
}

static void
mark_child_moved(xmlNode *old_child, xmlNode *new_parent, xmlNode *new_child,
                 int p_old, int p_new)
{
    xml_node_private_t *nodepriv = new_child->_private;

    crm_trace("Child element %s with "
              PCMK_XA_ID "='%s' moved from position %d to %d under %s",
              new_child->name, pcmk__s(pcmk__xe_id(new_child), "<no id>"),
              p_old, p_new, new_parent->name);
    pcmk__mark_xml_node_dirty(new_parent);
    pcmk__set_xml_flags(nodepriv, pcmk__xf_moved);

    if (p_old > p_new) {
        nodepriv = old_child->_private;
    } else {
        nodepriv = new_child->_private;
    }
    pcmk__set_xml_flags(nodepriv, pcmk__xf_skip);
}

// Given original and new XML, mark new XML portions that have changed
static void
mark_xml_changes(xmlNode *old_xml, xmlNode *new_xml, bool check_top)
{
    xmlNode *old_child = NULL;
    xmlNode *new_child = NULL;
    xml_node_private_t *nodepriv = NULL;

    CRM_CHECK(new_xml != NULL, return);
    if (old_xml == NULL) {
        mark_xml_tree_dirty_created(new_xml);
        pcmk__apply_creation_acl(new_xml, check_top);
        return;
    }

    nodepriv = new_xml->_private;
    CRM_CHECK(nodepriv != NULL, return);

    if(nodepriv->flags & pcmk__xf_processed) {
        /* Avoid re-comparing nodes */
        return;
    }
    pcmk__set_xml_flags(nodepriv, pcmk__xf_processed);

    xml_diff_attrs(old_xml, new_xml);

    // Check for differences in the original children
    for (old_child = pcmk__xml_first_child(old_xml); old_child != NULL;
         old_child = pcmk__xml_next(old_child)) {

        new_child = pcmk__xml_match(new_xml, old_child, true);

        if (new_child != NULL) {
            mark_xml_changes(old_child, new_child, true);

        } else {
            mark_child_deleted(old_child, new_xml);
        }
    }

    // Check for moved or created children
    new_child = pcmk__xml_first_child(new_xml);
    while (new_child != NULL) {
        xmlNode *next = pcmk__xml_next(new_child);

        old_child = pcmk__xml_match(old_xml, new_child, true);

        if (old_child == NULL) {
            // This is a newly created child
            nodepriv = new_child->_private;
            pcmk__set_xml_flags(nodepriv, pcmk__xf_skip);

            // May free new_child
            mark_xml_changes(old_child, new_child, true);

        } else {
            /* Check for movement, we already checked for differences */
            int p_new = pcmk__xml_position(new_child, pcmk__xf_skip);
            int p_old = pcmk__xml_position(old_child, pcmk__xf_skip);

            if(p_old != p_new) {
                mark_child_moved(old_child, new_xml, new_child, p_old, p_new);
            }
        }

        new_child = next;
    }
}

void
xml_calculate_significant_changes(xmlNode *old_xml, xmlNode *new_xml)
{
    pcmk__set_xml_doc_flag(new_xml, pcmk__xf_lazy);
    xml_calculate_changes(old_xml, new_xml);
}

// Called functions may set the \p pcmk__xf_skip flag on parts of \p old_xml
void
xml_calculate_changes(xmlNode *old_xml, xmlNode *new_xml)
{
    CRM_CHECK((old_xml != NULL) && (new_xml != NULL)
              && pcmk__xe_is(old_xml, (const char *) new_xml->name)
              && pcmk__str_eq(pcmk__xe_id(old_xml), pcmk__xe_id(new_xml),
                              pcmk__str_none),
              return);

    if(xml_tracking_changes(new_xml) == FALSE) {
        xml_track_changes(new_xml, NULL, NULL, FALSE);
    }

    mark_xml_changes(old_xml, new_xml, FALSE);
}

void
pcmk__xml_init(void)
{
    // @TODO Try to find a better caller than crm_log_preinit()
    static bool initialized = false;

    if (!initialized) {
        initialized = true;

        /* Double the buffer size when the buffer needs to grow. The default
         * allocator XML_BUFFER_ALLOC_EXACT was found to cause poor performance
         * due to the number of reallocs.
         */
        xmlSetBufferAllocationScheme(XML_BUFFER_ALLOC_DOUBLEIT);

        // Load schemas into the cache
        pcmk__schema_init();
    }
}

void
pcmk__xml_cleanup(void)
{
    pcmk__schema_cleanup();
    xmlCleanupParser();
}

char *
pcmk__xml_artefact_root(enum pcmk__xml_artefact_ns ns)
{
    static const char *base = NULL;
    char *ret = NULL;

    if (base == NULL) {
        base = pcmk__env_option(PCMK__ENV_SCHEMA_DIRECTORY);
    }
    if (pcmk__str_empty(base)) {
        base = PCMK_SCHEMA_DIR;
    }

    switch (ns) {
        case pcmk__xml_artefact_ns_legacy_rng:
        case pcmk__xml_artefact_ns_legacy_xslt:
            ret = strdup(base);
            break;
        case pcmk__xml_artefact_ns_base_rng:
        case pcmk__xml_artefact_ns_base_xslt:
            ret = crm_strdup_printf("%s/base", base);
            break;
        default:
            crm_err("XML artefact family specified as %u not recognized", ns);
    }
    return ret;
}

static char *
find_artefact(enum pcmk__xml_artefact_ns ns, const char *path, const char *filespec)
{
    char *ret = NULL;

    switch (ns) {
        case pcmk__xml_artefact_ns_legacy_rng:
        case pcmk__xml_artefact_ns_base_rng:
            if (pcmk__ends_with(filespec, ".rng")) {
                ret = crm_strdup_printf("%s/%s", path, filespec);
            } else {
                ret = crm_strdup_printf("%s/%s.rng", path, filespec);
            }
            break;
        case pcmk__xml_artefact_ns_legacy_xslt:
        case pcmk__xml_artefact_ns_base_xslt:
            if (pcmk__ends_with(filespec, ".xsl")) {
                ret = crm_strdup_printf("%s/%s", path, filespec);
            } else {
                ret = crm_strdup_printf("%s/%s.xsl", path, filespec);
            }
            break;
        default:
            crm_err("XML artefact family specified as %u not recognized", ns);
    }

    return ret;
}

char *
pcmk__xml_artefact_path(enum pcmk__xml_artefact_ns ns, const char *filespec)
{
    struct stat sb;
    char *base = pcmk__xml_artefact_root(ns);
    char *ret = NULL;

    ret = find_artefact(ns, base, filespec);
    free(base);

    if (stat(ret, &sb) != 0 || !S_ISREG(sb.st_mode)) {
        const char *remote_schema_dir = pcmk__remote_schema_dir();

        free(ret);
        ret = find_artefact(ns, remote_schema_dir, filespec);
    }

    return ret;
}

// Deprecated functions kept only for backward API compatibility
// LCOV_EXCL_START

#include <crm/common/xml_compat.h>

xmlNode *
copy_xml(xmlNode *src)
{
    xmlDoc *doc = pcmk__xml_new_doc();
    xmlNode *copy = NULL;

    copy = xmlDocCopyNode(src, doc, 1);
    pcmk__mem_assert(copy);

    xmlDocSetRootElement(doc, copy);
    pcmk__xml_new_private_data(copy);
    return copy;
}

void
crm_xml_init(void)
{
    pcmk__xml_init();
}

void
crm_xml_cleanup(void)
{
    pcmk__xml_cleanup();
}

void
pcmk_free_xml_subtree(xmlNode *xml)
{
    pcmk__xml_free_node(xml);
}

void
free_xml(xmlNode *child)
{
    pcmk__xml_free(child);
}

void
crm_xml_sanitize_id(char *id)
{
    char *c;

    for (c = id; *c; ++c) {
        switch (*c) {
            case ':':
            case '#':
                *c = '.';
        }
    }
}

// LCOV_EXCL_STOP
// End deprecated API