entities.c

/*
 * entities.c : implementation for the XML entities handling
 *
 * See Copyright for the status of this software.
 *
 * daniel@veillard.com
 */

#define IN_LIBXML
#include "libxml.h"

#include <string.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <libxml/xmlmemory.h>
#include <libxml/hash.h>
#include <libxml/entities.h>
#include <libxml/parser.h>
#include <libxml/xmlerror.h>
#include <libxml/globals.h>

/*
 * The XML predefined entities.
 */

struct xmlPredefinedEntityValue {
    const char *name;
    const char *value;
};
static struct xmlPredefinedEntityValue xmlPredefinedEntityValues[] = {
    { "lt", "<" },
    { "gt", ">" },
    { "apos", "'" },
    { "quot", "\"" },
    { "amp", "&" }
};

/*
 * TODO: This is GROSS, allocation of a 256 entry hash for
 *       a fixed number of 4 elements !
 */
static xmlHashTablePtr xmlPredefinedEntities = NULL;

/*
 * xmlFreeEntity : clean-up an entity record.
 */
static void xmlFreeEntity(xmlEntityPtr entity) {
    if (entity == NULL) return;

    if ((entity->children) && (entity->owner == 1) &&
	(entity == (xmlEntityPtr) entity->children->parent))
	xmlFreeNodeList(entity->children);
    if (entity->name != NULL)
	xmlFree((char *) entity->name);
    if (entity->ExternalID != NULL)
        xmlFree((char *) entity->ExternalID);
    if (entity->SystemID != NULL)
        xmlFree((char *) entity->SystemID);
    if (entity->URI != NULL)
        xmlFree((char *) entity->URI);
    if (entity->content != NULL)
        xmlFree((char *) entity->content);
    if (entity->orig != NULL)
        xmlFree((char *) entity->orig);
    xmlFree(entity);
}

/*
 * xmlAddEntity : register a new entity for an entities table.
 */
static xmlEntityPtr
xmlAddEntity(xmlDtdPtr dtd, const xmlChar *name, int type,
	  const xmlChar *ExternalID, const xmlChar *SystemID,
	  const xmlChar *content) {
    xmlEntitiesTablePtr table = NULL;
    xmlEntityPtr ret;

    if (name == NULL)
	return(NULL);
    switch (type) {
        case XML_INTERNAL_GENERAL_ENTITY:
        case XML_EXTERNAL_GENERAL_PARSED_ENTITY:
        case XML_EXTERNAL_GENERAL_UNPARSED_ENTITY:
	    if (dtd->entities == NULL)
		dtd->entities = xmlHashCreate(0);
	    table = dtd->entities;
	    break;
        case XML_INTERNAL_PARAMETER_ENTITY:
        case XML_EXTERNAL_PARAMETER_ENTITY:
	    if (dtd->pentities == NULL)
		dtd->pentities = xmlHashCreate(0);
	    table = dtd->pentities;
	    break;
        case XML_INTERNAL_PREDEFINED_ENTITY:
	    if (xmlPredefinedEntities == NULL)
		xmlPredefinedEntities = xmlHashCreate(8);
	    table = xmlPredefinedEntities;
    }
    if (table == NULL)
	return(NULL);
    ret = (xmlEntityPtr) xmlMalloc(sizeof(xmlEntity));
    if (ret == NULL) {
	xmlGenericError(xmlGenericErrorContext,
		"xmlAddEntity: out of memory\n");
	return(NULL);
    }
    memset(ret, 0, sizeof(xmlEntity));
    ret->type = XML_ENTITY_DECL;

    /*
     * fill the structure.
     */
    ret->name = xmlStrdup(name);
    ret->etype = (xmlEntityType) type;
    if (ExternalID != NULL)
	ret->ExternalID = xmlStrdup(ExternalID);
    if (SystemID != NULL)
	ret->SystemID = xmlStrdup(SystemID);
    if (content != NULL) {
        ret->length = xmlStrlen(content);
	ret->content = xmlStrndup(content, ret->length);
     } else {
        ret->length = 0;
        ret->content = NULL;
    }
    ret->URI = NULL; /* to be computed by the layer knowing
			the defining entity */
    ret->orig = NULL;
    ret->owner = 0;

    if (xmlHashAddEntry(table, name, ret)) {
	/*
	 * entity was already defined at another level.
	 */
        xmlFreeEntity(ret);
	return(NULL);
    }
    return(ret);
}

/**
 * xmlInitializePredefinedEntities:
 *
 * Set up the predefined entities.
 */
void xmlInitializePredefinedEntities(void) {
    unsigned int i;
    xmlChar name[50];
    xmlChar value[50];
    const char *in;
    xmlChar *out;

    if (xmlPredefinedEntities != NULL) return;

    xmlPredefinedEntities = xmlCreateEntitiesTable();
    for (i = 0;i < sizeof(xmlPredefinedEntityValues) / 
                   sizeof(xmlPredefinedEntityValues[0]);i++) {
        in = xmlPredefinedEntityValues[i].name;
	out = &name[0];
	for (;(*out++ = (xmlChar) *in);)in++;
        in = xmlPredefinedEntityValues[i].value;
	out = &value[0];
	for (;(*out++ = (xmlChar) *in);)in++;

        xmlAddEntity(NULL, (const xmlChar *) &name[0],
	             XML_INTERNAL_PREDEFINED_ENTITY, NULL, NULL,
		     &value[0]);
    }
}

/**
 * xmlCleanupPredefinedEntities:
 *
 * Cleanup up the predefined entities table.
 */
void xmlCleanupPredefinedEntities(void) {
    if (xmlPredefinedEntities == NULL) return;

    xmlFreeEntitiesTable(xmlPredefinedEntities);
    xmlPredefinedEntities = NULL;
}

/**
 * xmlGetPredefinedEntity:
 * @name:  the entity name
 *
 * Check whether this name is an predefined entity.
 *
 * Returns NULL if not, otherwise the entity
 */
xmlEntityPtr
xmlGetPredefinedEntity(const xmlChar *name) {
    if (xmlPredefinedEntities == NULL)
        xmlInitializePredefinedEntities();
    return((xmlEntityPtr) xmlHashLookup(xmlPredefinedEntities, name));
}

/**
 * xmlAddDtdEntity:
 * @doc:  the document
 * @name:  the entity name
 * @type:  the entity type XML_xxx_yyy_ENTITY
 * @ExternalID:  the entity external ID if available
 * @SystemID:  the entity system ID if available
 * @content:  the entity content
 *
 * Register a new entity for this document DTD external subset.
 *
 * Returns a pointer to the entity or NULL in case of error
 */
xmlEntityPtr
xmlAddDtdEntity(xmlDocPtr doc, const xmlChar *name, int type,
	        const xmlChar *ExternalID, const xmlChar *SystemID,
		const xmlChar *content) {
    xmlEntityPtr ret;
    xmlDtdPtr dtd;

    if (doc == NULL) {
        xmlGenericError(xmlGenericErrorContext,
	        "xmlAddDtdEntity: doc == NULL !\n");
	return(NULL);
    }
    if (doc->extSubset == NULL) {
        xmlGenericError(xmlGenericErrorContext,
	        "xmlAddDtdEntity: document without external subset !\n");
	return(NULL);
    }
    dtd = doc->extSubset;
    ret = xmlAddEntity(dtd, name, type, ExternalID, SystemID, content);
    if (ret == NULL) return(NULL);

    /*
     * Link it to the DTD
     */
    ret->parent = dtd;
    ret->doc = dtd->doc;
    if (dtd->last == NULL) {
	dtd->children = dtd->last = (xmlNodePtr) ret;
    } else {
        dtd->last->next = (xmlNodePtr) ret;
	ret->prev = dtd->last;
	dtd->last = (xmlNodePtr) ret;
    }
    return(ret);
}

/**
 * xmlAddDocEntity:
 * @doc:  the document
 * @name:  the entity name
 * @type:  the entity type XML_xxx_yyy_ENTITY
 * @ExternalID:  the entity external ID if available
 * @SystemID:  the entity system ID if available
 * @content:  the entity content
 *
 * Register a new entity for this document.
 *
 * Returns a pointer to the entity or NULL in case of error
 */
xmlEntityPtr
xmlAddDocEntity(xmlDocPtr doc, const xmlChar *name, int type,
	        const xmlChar *ExternalID, const xmlChar *SystemID,
	        const xmlChar *content) {
    xmlEntityPtr ret;
    xmlDtdPtr dtd;

    if (doc == NULL) {
        xmlGenericError(xmlGenericErrorContext,
	        "xmlAddDocEntity: document is NULL !\n");
	return(NULL);
    }
    if (doc->intSubset == NULL) {
        xmlGenericError(xmlGenericErrorContext,
	        "xmlAddDocEntity: document without internal subset !\n");
	return(NULL);
    }
    dtd = doc->intSubset;
    ret = xmlAddEntity(dtd, name, type, ExternalID, SystemID, content);
    if (ret == NULL) return(NULL);

    /*
     * Link it to the DTD
     */
    ret->parent = dtd;
    ret->doc = dtd->doc;
    if (dtd->last == NULL) {
	dtd->children = dtd->last = (xmlNodePtr) ret;
    } else {
	dtd->last->next = (xmlNodePtr) ret;
	ret->prev = dtd->last;
	dtd->last = (xmlNodePtr) ret;
    }
    return(ret);
}

/**
 * xmlGetEntityFromTable:
 * @table:  an entity table
 * @name:  the entity name
 * @parameter:  look for parameter entities
 *
 * Do an entity lookup in the table.
 * returns the corresponding parameter entity, if found.
 * 
 * Returns A pointer to the entity structure or NULL if not found.
 */
static xmlEntityPtr
xmlGetEntityFromTable(xmlEntitiesTablePtr table, const xmlChar *name) {
    return((xmlEntityPtr) xmlHashLookup(table, name));
}

/**
 * xmlGetParameterEntity:
 * @doc:  the document referencing the entity
 * @name:  the entity name
 *
 * Do an entity lookup in the internal and external subsets and
 * returns the corresponding parameter entity, if found.
 * 
 * Returns A pointer to the entity structure or NULL if not found.
 */
xmlEntityPtr
xmlGetParameterEntity(xmlDocPtr doc, const xmlChar *name) {
    xmlEntitiesTablePtr table;
    xmlEntityPtr ret;

    if (doc == NULL)
	return(NULL);
    if ((doc->intSubset != NULL) && (doc->intSubset->pentities != NULL)) {
	table = (xmlEntitiesTablePtr) doc->intSubset->pentities;
	ret = xmlGetEntityFromTable(table, name);
	if (ret != NULL)
	    return(ret);
    }
    if ((doc->extSubset != NULL) && (doc->extSubset->pentities != NULL)) {
	table = (xmlEntitiesTablePtr) doc->extSubset->pentities;
	return(xmlGetEntityFromTable(table, name));
    }
    return(NULL);
}

/**
 * xmlGetDtdEntity:
 * @doc:  the document referencing the entity
 * @name:  the entity name
 *
 * Do an entity lookup in the DTD entity hash table and
 * returns the corresponding entity, if found.
 * Note: the first argument is the document node, not the DTD node.
 * 
 * Returns A pointer to the entity structure or NULL if not found.
 */
xmlEntityPtr
xmlGetDtdEntity(xmlDocPtr doc, const xmlChar *name) {
    xmlEntitiesTablePtr table;

    if (doc == NULL)
	return(NULL);
    if ((doc->extSubset != NULL) && (doc->extSubset->entities != NULL)) {
	table = (xmlEntitiesTablePtr) doc->extSubset->entities;
	return(xmlGetEntityFromTable(table, name));
    }
    return(NULL);
}

/**
 * xmlGetDocEntity:
 * @doc:  the document referencing the entity
 * @name:  the entity name
 *
 * Do an entity lookup in the document entity hash table and
 * returns the corresponding entity, otherwise a lookup is done
 * in the predefined entities too.
 * 
 * Returns A pointer to the entity structure or NULL if not found.
 */
xmlEntityPtr
xmlGetDocEntity(xmlDocPtr doc, const xmlChar *name) {
    xmlEntityPtr cur;
    xmlEntitiesTablePtr table;

    if (doc != NULL) {
	if ((doc->intSubset != NULL) && (doc->intSubset->entities != NULL)) {
	    table = (xmlEntitiesTablePtr) doc->intSubset->entities;
	    cur = xmlGetEntityFromTable(table, name);
	    if (cur != NULL)
		return(cur);
	}
	if (doc->standalone != 1) {
	    if ((doc->extSubset != NULL) &&
		(doc->extSubset->entities != NULL)) {
		table = (xmlEntitiesTablePtr) doc->extSubset->entities;
		cur = xmlGetEntityFromTable(table, name);
		if (cur != NULL)
		    return(cur);
	    }
	}
    }
    if (xmlPredefinedEntities == NULL)
        xmlInitializePredefinedEntities();
    table = xmlPredefinedEntities;
    return(xmlGetEntityFromTable(table, name));
}

/*
 * [2] Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD]
 *                  | [#x10000-#x10FFFF]
 * any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.
 */
#define IS_CHAR(c)							\
    (((c) == 0x09) || ((c) == 0x0a) || ((c) == 0x0d) ||			\
     (((c) >= 0x20) && ((c) != 0xFFFE) && ((c) != 0xFFFF)))

/*
 * A buffer used for converting entities to their equivalent and back.
 */
static int static_buffer_size = 0;
static xmlChar *static_buffer = NULL;

static int growBuffer(void) {
    static_buffer_size *= 2;
    static_buffer = (xmlChar *) xmlRealloc(static_buffer,
	                                static_buffer_size * sizeof(xmlChar));
    if (static_buffer == NULL) {
        xmlGenericError(xmlGenericErrorContext, "malloc failed\n");
	return(-1);
    }
    return(0);
}


/**
 * xmlEncodeEntities:
 * @doc:  the document containing the string
 * @input:  A string to convert to XML.
 *
 * Do a global encoding of a string, replacing the predefined entities
 * and non ASCII values with their entities and CharRef counterparts.
 *
 * TODO: remove xmlEncodeEntities, once we are not afraid of breaking binary
 *       compatibility
 *
 * People must migrate their code to xmlEncodeEntitiesReentrant !
 * This routine will issue a warning when encountered.
 * 
 * Returns A newly allocated string with the substitution done.
 */
const xmlChar *
xmlEncodeEntities(xmlDocPtr doc, const xmlChar *input) {
    const xmlChar *cur = input;
    xmlChar *out = static_buffer;
    static int warning = 1;
    int html = 0;


    if (warning) {
    xmlGenericError(xmlGenericErrorContext,
	    "Deprecated API xmlEncodeEntities() used\n");
    xmlGenericError(xmlGenericErrorContext,
	    "   change code to use xmlEncodeEntitiesReentrant()\n");
    warning = 0;
    }

    if (input == NULL) return(NULL);
    if (doc != NULL)
        html = (doc->type == XML_HTML_DOCUMENT_NODE);

    if (static_buffer == NULL) {
        static_buffer_size = 1000;
        static_buffer = (xmlChar *)
	    xmlMalloc(static_buffer_size * sizeof(xmlChar));
	if (static_buffer == NULL) {
	    xmlGenericError(xmlGenericErrorContext, "malloc failed\n");
            return(NULL);
	}
	out = static_buffer;
    }
    while (*cur != '\0') {
        if (out - static_buffer > static_buffer_size - 100) {
	    int indx = out - static_buffer;

	    growBuffer();
	    out = &static_buffer[indx];
	}

	/*
	 * By default one have to encode at least '<', '>', '"' and '&' !
	 */
	if (*cur == '<') {
	    *out++ = '&';
	    *out++ = 'l';
	    *out++ = 't';
	    *out++ = ';';
	} else if (*cur == '>') {
	    *out++ = '&';
	    *out++ = 'g';
	    *out++ = 't';
	    *out++ = ';';
	} else if (*cur == '&') {
	    *out++ = '&';
	    *out++ = 'a';
	    *out++ = 'm';
	    *out++ = 'p';
	    *out++ = ';';
	} else if (*cur == '"') {
	    *out++ = '&';
	    *out++ = 'q';
	    *out++ = 'u';
	    *out++ = 'o';
	    *out++ = 't';
	    *out++ = ';';
	} else if ((*cur == '\'') && (!html)) {
	    *out++ = '&';
	    *out++ = 'a';
	    *out++ = 'p';
	    *out++ = 'o';
	    *out++ = 's';
	    *out++ = ';';
	} else if (((*cur >= 0x20) && (*cur < 0x80)) ||
	    (*cur == '\n') || (*cur == '\r') || (*cur == '\t')) {
	    /*
	     * default case, just copy !
	     */
	    *out++ = *cur;
#ifndef USE_UTF_8
	} else if ((sizeof(xmlChar) == 1) && (*cur >= 0x80)) {
	    char buf[10], *ptr;

	    snprintf(buf, sizeof(buf), "&#%d;", *cur);
            buf[sizeof(buf) - 1] = 0;
            ptr = buf;
	    while (*ptr != 0) *out++ = *ptr++;
#endif
	} else if (IS_CHAR(*cur)) {
	    char buf[10], *ptr;

	    snprintf(buf, sizeof(buf), "&#%d;", *cur);
            buf[sizeof(buf) - 1] = 0;
            ptr = buf;
	    while (*ptr != 0) *out++ = *ptr++;
	}
#if 0
	else {
	    /*
	     * default case, this is not a valid char !
	     * Skip it...
	     */
	    xmlGenericError(xmlGenericErrorContext,
		    "xmlEncodeEntities: invalid char %d\n", (int) *cur);
	}
#endif
	cur++;
    }
    *out++ = 0;
    return(static_buffer);
}

/*
 * Macro used to grow the current buffer.
 */
#define growBufferReentrant() {						\
    buffer_size *= 2;							\
    buffer = (xmlChar *)						\
    		xmlRealloc(buffer, buffer_size * sizeof(xmlChar));	\
    if (buffer == NULL) {						\
	xmlGenericError(xmlGenericErrorContext, "realloc failed\n");	\
	return(NULL);							\
    }									\
}


/**
 * xmlEncodeEntitiesReentrant:
 * @doc:  the document containing the string
 * @input:  A string to convert to XML.
 *
 * Do a global encoding of a string, replacing the predefined entities
 * and non ASCII values with their entities and CharRef counterparts.
 * Contrary to xmlEncodeEntities, this routine is reentrant, and result
 * must be deallocated.
 *
 * Returns A newly allocated string with the substitution done.
 */
xmlChar *
xmlEncodeEntitiesReentrant(xmlDocPtr doc, const xmlChar *input) {
    const xmlChar *cur = input;
    xmlChar *buffer = NULL;
    xmlChar *out = NULL;
    int buffer_size = 0;
    int html = 0;

    if (input == NULL) return(NULL);
    if (doc != NULL)
        html = (doc->type == XML_HTML_DOCUMENT_NODE);

    /*
     * allocate an translation buffer.
     */
    buffer_size = 1000;
    buffer = (xmlChar *) xmlMalloc(buffer_size * sizeof(xmlChar));
    if (buffer == NULL) {
	xmlGenericError(xmlGenericErrorContext, "malloc failed\n");
	return(NULL);
    }
    out = buffer;

    while (*cur != '\0') {
        if (out - buffer > buffer_size - 100) {
	    int indx = out - buffer;

	    growBufferReentrant();
	    out = &buffer[indx];
	}

	/*
	 * By default one have to encode at least '<', '>', '"' and '&' !
	 */
	if (*cur == '<') {
	    *out++ = '&';
	    *out++ = 'l';
	    *out++ = 't';
	    *out++ = ';';
	} else if (*cur == '>') {
	    *out++ = '&';
	    *out++ = 'g';
	    *out++ = 't';
	    *out++ = ';';
	} else if (*cur == '&') {
	    *out++ = '&';
	    *out++ = 'a';
	    *out++ = 'm';
	    *out++ = 'p';
	    *out++ = ';';
	} else if (*cur == '"') {
	    *out++ = '&';
	    *out++ = 'q';
	    *out++ = 'u';
	    *out++ = 'o';
	    *out++ = 't';
	    *out++ = ';';
#if 0
	} else if ((*cur == '\'') && (!html)) {
	    *out++ = '&';
	    *out++ = 'a';
	    *out++ = 'p';
	    *out++ = 'o';
	    *out++ = 's';
	    *out++ = ';';
#endif
	} else if (((*cur >= 0x20) && (*cur < 0x80)) ||
	    (*cur == '\n') || (*cur == '\r') || (*cur == '\t')) {
	    /*
	     * default case, just copy !
	     */
	    *out++ = *cur;
	} else if (*cur >= 0x80) {
	    if (((doc != NULL) && (doc->encoding != NULL)) || (html)) {
		/*
		 * Bjørn Reese <br@sseusa.com> provided the patch
	        xmlChar xc;
	        xc = (*cur & 0x3F) << 6;
	        if (cur[1] != 0) {
		    xc += *(++cur) & 0x3F;
		    *out++ = xc;
	        } else
		 */
		    *out++ = *cur;
	    } else {
		/*
		 * We assume we have UTF-8 input.
		 */
		char buf[10], *ptr;
		int val = 0, l = 1;

		if (*cur < 0xC0) {
		    xmlGenericError(xmlGenericErrorContext,
			    "xmlEncodeEntitiesReentrant : input not UTF-8\n");
		    if (doc != NULL)
			doc->encoding = xmlStrdup(BAD_CAST "ISO-8859-1");
		    snprintf(buf, sizeof(buf), "&#%d;", *cur);
		    buf[sizeof(buf) - 1] = 0;
		    ptr = buf;
		    while (*ptr != 0) *out++ = *ptr++;
		    cur++;
		    continue;
		} else if (*cur < 0xE0) {
                    val = (cur[0]) & 0x1F;
		    val <<= 6;
		    val |= (cur[1]) & 0x3F;
		    l = 2;
		} else if (*cur < 0xF0) {
                    val = (cur[0]) & 0x0F;
		    val <<= 6;
		    val |= (cur[1]) & 0x3F;
		    val <<= 6;
		    val |= (cur[2]) & 0x3F;
		    l = 3;
		} else if (*cur < 0xF8) {
                    val = (cur[0]) & 0x07;
		    val <<= 6;
		    val |= (cur[1]) & 0x3F;
		    val <<= 6;
		    val |= (cur[2]) & 0x3F;
		    val <<= 6;
		    val |= (cur[3]) & 0x3F;
		    l = 4;
		}
		if ((l == 1) || (!IS_CHAR(val))) {
		    xmlGenericError(xmlGenericErrorContext,
			"xmlEncodeEntitiesReentrant : char out of range\n");
		    if (doc != NULL)
			doc->encoding = xmlStrdup(BAD_CAST "ISO-8859-1");
		    snprintf(buf, sizeof(buf), "&#%d;", *cur);
		    buf[sizeof(buf) - 1] = 0;
		    ptr = buf;
		    while (*ptr != 0) *out++ = *ptr++;
		    cur++;
		    continue;
		}
		/*
		 * We could do multiple things here. Just save as a char ref
		 */
		if (html)
		    snprintf(buf, sizeof(buf), "&#%d;", val);
		else
		    snprintf(buf, sizeof(buf), "&#x%X;", val);
		buf[sizeof(buf) - 1] = 0;
		ptr = buf;
		while (*ptr != 0) *out++ = *ptr++;
		cur += l;
		continue;
	    }
	} else if (IS_CHAR(*cur)) {
	    char buf[10], *ptr;

	    snprintf(buf, sizeof(buf), "&#%d;", *cur);
	    buf[sizeof(buf) - 1] = 0;
            ptr = buf;
	    while (*ptr != 0) *out++ = *ptr++;
	}
#if 0
	else {
	    /*
	     * default case, this is not a valid char !
	     * Skip it...
	     */
	    xmlGenericError(xmlGenericErrorContext,
		    "xmlEncodeEntities: invalid char %d\n", (int) *cur);
	}
#endif
	cur++;
    }
    *out++ = 0;
    return(buffer);
}

/**
 * xmlEncodeSpecialChars:
 * @doc:  the document containing the string
 * @input:  A string to convert to XML.
 *
 * Do a global encoding of a string, replacing the predefined entities
 * this routine is reentrant, and result must be deallocated.
 *
 * Returns A newly allocated string with the substitution done.
 */
xmlChar *
xmlEncodeSpecialChars(xmlDocPtr doc, const xmlChar *input) {
    const xmlChar *cur = input;
    xmlChar *buffer = NULL;
    xmlChar *out = NULL;
    int buffer_size = 0;
    int html = 0;

    if (input == NULL) return(NULL);
    if (doc != NULL)
        html = (doc->type == XML_HTML_DOCUMENT_NODE);

    /*
     * allocate an translation buffer.
     */
    buffer_size = 1000;
    buffer = (xmlChar *) xmlMalloc(buffer_size * sizeof(xmlChar));
    if (buffer == NULL) {
	xmlGenericError(xmlGenericErrorContext, "malloc failed\n");
	return(NULL);
    }
    out = buffer;

    while (*cur != '\0') {
        if (out - buffer > buffer_size - 10) {
	    int indx = out - buffer;

	    growBufferReentrant();
	    out = &buffer[indx];
	}

	/*
	 * By default one have to encode at least '<', '>', '"' and '&' !
	 */
	if (*cur == '<') {
	    *out++ = '&';
	    *out++ = 'l';
	    *out++ = 't';
	    *out++ = ';';
	} else if (*cur == '>') {
	    *out++ = '&';
	    *out++ = 'g';
	    *out++ = 't';
	    *out++ = ';';
	} else if (*cur == '&') {
	    *out++ = '&';
	    *out++ = 'a';
	    *out++ = 'm';
	    *out++ = 'p';
	    *out++ = ';';
	} else if (*cur == '"') {
	    *out++ = '&';
	    *out++ = 'q';
	    *out++ = 'u';
	    *out++ = 'o';
	    *out++ = 't';
	    *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);
}

/**
 * xmlCreateEntitiesTable:
 *
 * create and initialize an empty entities hash table.
 *
 * Returns the xmlEntitiesTablePtr just created or NULL in case of error.
 */
xmlEntitiesTablePtr
xmlCreateEntitiesTable(void) {
    return((xmlEntitiesTablePtr) xmlHashCreate(0));
}

/**
 * xmlFreeEntityWrapper:
 * @entity:  An entity
 * @name:  its name
 *
 * Deallocate the memory used by an entities in the hash table.
 */
static void
xmlFreeEntityWrapper(xmlEntityPtr entity,
	               const xmlChar *name ATTRIBUTE_UNUSED) {
    if (entity != NULL)
	xmlFreeEntity(entity);
}

/**
 * xmlFreeEntitiesTable:
 * @table:  An entity table
 *
 * Deallocate the memory used by an entities hash table.
 */
void
xmlFreeEntitiesTable(xmlEntitiesTablePtr table) {
    xmlHashFree(table, (xmlHashDeallocator) xmlFreeEntityWrapper);
}

/**
 * xmlCopyEntity:
 * @ent:  An entity
 *
 * Build a copy of an entity
 * 
 * Returns the new xmlEntitiesPtr or NULL in case of error.
 */
static xmlEntityPtr
xmlCopyEntity(xmlEntityPtr ent) {
    xmlEntityPtr cur;

    cur = (xmlEntityPtr) xmlMalloc(sizeof(xmlEntity));
    if (cur == NULL) {
	xmlGenericError(xmlGenericErrorContext,
		"xmlCopyEntity: out of memory !\n");
	return(NULL);
    }
    memset(cur, 0, sizeof(xmlEntity));
    cur->type = XML_ENTITY_DECL;

    cur->etype = ent->etype;
    if (ent->name != NULL)
	cur->name = xmlStrdup(ent->name);
    if (ent->ExternalID != NULL)
	cur->ExternalID = xmlStrdup(ent->ExternalID);
    if (ent->SystemID != NULL)
	cur->SystemID = xmlStrdup(ent->SystemID);
    if (ent->content != NULL)
	cur->content = xmlStrdup(ent->content);
    if (ent->orig != NULL)
	cur->orig = xmlStrdup(ent->orig);
    if (ent->URI != NULL)
	cur->URI = xmlStrdup(ent->URI);
    return(cur);
}

/**
 * xmlCopyEntitiesTable:
 * @table:  An entity table
 *
 * Build a copy of an entity table.
 * 
 * Returns the new xmlEntitiesTablePtr or NULL in case of error.
 */
xmlEntitiesTablePtr
xmlCopyEntitiesTable(xmlEntitiesTablePtr table) {
    return(xmlHashCopy(table, (xmlHashCopier) xmlCopyEntity));
}

/**
 * xmlDumpEntityDecl:
 * @buf:  An XML buffer.
 * @ent:  An entity table
 *
 * This will dump the content of the entity table as an XML DTD definition
 */
void
xmlDumpEntityDecl(xmlBufferPtr buf, xmlEntityPtr ent) {
    switch (ent->etype) {
	case XML_INTERNAL_GENERAL_ENTITY:
	    xmlBufferWriteChar(buf, "<!ENTITY ");
	    xmlBufferWriteCHAR(buf, ent->name);
	    xmlBufferWriteChar(buf, " ");
	    if (ent->orig != NULL)
		xmlBufferWriteQuotedString(buf, ent->orig);
	    else
		xmlBufferWriteQuotedString(buf, ent->content);
	    xmlBufferWriteChar(buf, ">\n");
	    break;
	case XML_EXTERNAL_GENERAL_PARSED_ENTITY:
	    xmlBufferWriteChar(buf, "<!ENTITY ");
	    xmlBufferWriteCHAR(buf, ent->name);
	    if (ent->ExternalID != NULL) {
		 xmlBufferWriteChar(buf, " PUBLIC ");
		 xmlBufferWriteQuotedString(buf, ent->ExternalID);
		 xmlBufferWriteChar(buf, " ");
		 xmlBufferWriteQuotedString(buf, ent->SystemID);
	    } else {
		 xmlBufferWriteChar(buf, " SYSTEM ");
		 xmlBufferWriteQuotedString(buf, ent->SystemID);
	    }
	    xmlBufferWriteChar(buf, ">\n");
	    break;
	case XML_EXTERNAL_GENERAL_UNPARSED_ENTITY:
	    xmlBufferWriteChar(buf, "<!ENTITY ");
	    xmlBufferWriteCHAR(buf, ent->name);
	    if (ent->ExternalID != NULL) {
		 xmlBufferWriteChar(buf, " PUBLIC ");
		 xmlBufferWriteQuotedString(buf, ent->ExternalID);
		 xmlBufferWriteChar(buf, " ");
		 xmlBufferWriteQuotedString(buf, ent->SystemID);
	    } else {
		 xmlBufferWriteChar(buf, " SYSTEM ");
		 xmlBufferWriteQuotedString(buf, ent->SystemID);
	    }
	    if (ent->content != NULL) { /* Should be true ! */
		xmlBufferWriteChar(buf, " NDATA ");
		if (ent->orig != NULL)
		    xmlBufferWriteCHAR(buf, ent->orig);
		else
		    xmlBufferWriteCHAR(buf, ent->content);
	    }
	    xmlBufferWriteChar(buf, ">\n");
	    break;
	case XML_INTERNAL_PARAMETER_ENTITY:
	    xmlBufferWriteChar(buf, "<!ENTITY % ");
	    xmlBufferWriteCHAR(buf, ent->name);
	    xmlBufferWriteChar(buf, " ");
	    if (ent->orig == NULL)
		xmlBufferWriteQuotedString(buf, ent->content);
	    else
		xmlBufferWriteQuotedString(buf, ent->orig);
	    xmlBufferWriteChar(buf, ">\n");
	    break;
	case XML_EXTERNAL_PARAMETER_ENTITY:
	    xmlBufferWriteChar(buf, "<!ENTITY % ");
	    xmlBufferWriteCHAR(buf, ent->name);
	    if (ent->ExternalID != NULL) {
		 xmlBufferWriteChar(buf, " PUBLIC ");
		 xmlBufferWriteQuotedString(buf, ent->ExternalID);
		 xmlBufferWriteChar(buf, " ");
		 xmlBufferWriteQuotedString(buf, ent->SystemID);
	    } else {
		 xmlBufferWriteChar(buf, " SYSTEM ");
		 xmlBufferWriteQuotedString(buf, ent->SystemID);
	    }
	    xmlBufferWriteChar(buf, ">\n");
	    break;
	default:
	    xmlGenericError(xmlGenericErrorContext,
		"xmlDumpEntitiesDecl: internal: unknown type %d\n",
		    ent->etype);
    }
}

/**
 * xmlDumpEntitiesTable:
 * @buf:  An XML buffer.
 * @table:  An entity table
 *
 * This will dump the content of the entity table as an XML DTD definition
 */
void
xmlDumpEntitiesTable(xmlBufferPtr buf, xmlEntitiesTablePtr table) {
    xmlHashScan(table, (xmlHashScanner)xmlDumpEntityDecl, buf);
}