xmlparser.c

/*************************************************************************/
/*                                                                       */
/* Copyright (c) 1997-98 Richard Tobin, Language Technology Group, HCRC, */
/* University of Edinburgh.                                              */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,     */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHOR OR THE UNIVERSITY OF EDINBURGH BE LIABLE */
/* FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF    */
/* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION    */
/* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.       */
/*                                                                       */
/*************************************************************************/
/*  $Id: xmlparser.c,v 1.3 2004/05/04 00:00:17 awb Exp $     */

#ifndef lint
static char vcid[] = "$Id: xmlparser.c,v 1.3 2004/05/04 00:00:17 awb Exp $";
#endif /* lint */

/* 
 * XML (and nSGML) parser.
 * Author: Richard Tobin.
 */

#include <stdarg.h>
#include <stdlib.h>

#ifdef FOR_LT

#include "lt-memory.h"
#include "nsllib.h"

#define Malloc salloc
#define Realloc srealloc
#define Free sfree

#else

#include "system.h"

#endif

#include "charset.h"
#include "string16.h"
#include "ctype16.h"
#include "dtd.h"
#include "input.h"
#include "stdio16.h"
#include "xmlparser.h"

static int transcribe(Parser p, int back, int count);
static void pop_while_at_eoe(Parser p);
static void maybe_uppercase(Parser p, Char *s);
static void maybe_uppercase_name(Parser p);
static int str_maybecase_cmp8(Parser p, const char8 *a, const char8 *b);
static int is_ascii_alpha(int c);
static int is_ascii_digit(int c);
static int parse_external_id(Parser p, int required, 
                 char8 **publicid, char8 **systemid, 
                 int preq, int sreq);
static int parse_conditional(Parser p);
static int parse_notation_decl(Parser p);
static int parse_entity_decl(Parser p, Entity ent, int line, int chpos);
static int parse_attlist_decl(Parser p);
static int parse_element_decl(Parser p);
static ContentParticle parse_cp(Parser p);
static ContentParticle parse_choice_or_seq(Parser p);
static ContentParticle parse_choice_or_seq_1(Parser p, int nchildren,char sep);
static int check_content_decl(Parser p, ContentParticle cp);
static int check_content_decl_1(Parser p, ContentParticle cp);
static Char *stringify_cp(ContentParticle cp);
static void print_cp(ContentParticle cp, FILE16 *f);
static int size_cp(ContentParticle cp);
void FreeContentParticle(ContentParticle cp);
static int parse_reference(Parser p, int pe, int expand, int allow_external);
static int parse_character_reference(Parser p, int expand);
static const char8 *escape(int c);
static int parse_name(Parser p, const char8 *where);
static int parse_nmtoken(Parser p, const char8 *where);
static int looking_at(Parser p, const char8 *string);
static void clear_xbit(XBit xbit);
static int expect(Parser p, int expected, const char8 *where);
static int expect_dtd_whitespace(Parser p, const char8 *where);
static void skip_whitespace(InputSource s);
static int skip_dtd_whitespace(Parser p, int allow_pe);
static int parse_cdata(Parser p);
static int process_nsl_decl(Parser p);
static int process_xml_decl(Parser p);
static int parse_dtd(Parser p);
static int read_markupdecls(Parser p);
static int error(Parser p, const char8 *format, ...);
static void warn(Parser p, const char8 *format, ...);
static void verror(XBit bit, const char8 *format, va_list args);
enum literal_type {LT_cdata_attr, LT_tok_attr, LT_plain, LT_entity};
static int parse_string(Parser p, const char8 *where, enum literal_type type);
static int parse_pi(Parser p);
static int parse_comment(Parser p, int skip);
static int parse_pcdata(Parser p);
static int parse_starttag(Parser p);
static int parse_attribute(Parser p);
static int parse_endtag(Parser p);
static int parse_markup(Parser p);
static int parse(Parser p);
static int parse_markupdecl(Parser p);

#define require(x)  if(x >= 0) {} else return -1
#define require0(x) if(x >= 0) {} else return 0

#define Consume(buf) (buf = 0, buf##size = 0)
#define ExpandBuf(buf, sz) \
    if(buf##size >= (sz)+1) {} else if((buf = Realloc(buf, (buf##size = sz + 1) * sizeof(Char)))) {} else return error(p, "System error")

#define CopyName(n) if((n = Malloc((p->namelen + 1)*sizeof(Char)))) {memcpy(n, p->name, p->namelen * sizeof(Char)); n[p->namelen] = 0;} else return error(p, "System error");

#define CopyName0(n) if((n = Malloc((p->namelen + 1)*sizeof(Char)))) {memcpy(n, p->name, p->namelen * sizeof(Char)); n[p->namelen] = 0;} else {error(p, "System error"); return 0;}

const char8 *XBitTypeName[XBIT_enum_count] = {
    "dtd",
    "start",
    "empty",
    "end",
    "eof",
    "pcdata",
    "pi",
    "comment",
    "cdsect",
    "xml",
    "error",
    "warning",
    "none"
};

static Entity xml_builtin_entity;
static Entity xml_predefined_entities;

int ParserInit(void)
{
    static int initialised = 0;
    Entity e, f;
    int i;
    static const Char lt[] = {'l','t',0}, ltval[] = {'&','#','6','0',';',0};
    static const Char gt[] = {'g','t',0}, gtval[] = {'&','#','6','2',';',0};
    static const Char amp[] = {'a','m','p',0},
              ampval[] = {'&','#','3','8',';',0};
    static const Char apos[] = {'a','p','o','s',0}, aposval[] = {'\'',0};
    static const Char quot[] = {'q','u','o','t',0}, quotval[] = {'"',0};
    static const Char *builtins[5][2] = {
    {lt, ltval}, {gt, gtval}, {amp, ampval},
    {apos, aposval}, {quot, quotval}
    };
    (void)vcid;

    if(initialised)
    return 0;
    initialised = 1;

    init_charset();
    init_ctype16();
    init_stdio16();

    for(i=0, f=0; i<5; i++, f=e)
    {
    e = NewInternalEntity(builtins[i][0], builtins[i][1],
                  xml_builtin_entity, 0, 0, 0);
    if(!e)
        return -1;
    e->next = f;
    }

    xml_predefined_entities = e;

    return 0;
}

static void skip_whitespace(InputSource s)
{
    int c;

    while((c = get(s)) != XEOE && is_xml_whitespace(c))
    ;
    unget(s);
}

/* 
 * Skip whitespace and (optionally) the start and end of PEs.  Return 1 if
 * there actually *was* some whitespace or a PE start/end, -1 if
 * an error occurred, 0 otherwise.
 */

static int skip_dtd_whitespace(Parser p, int allow_pe)
{
    int c;
    int got_some = 0;
    InputSource s = p->source;

    while(1)
    {
    c = get(s);

    if(c == XEOE)
    {
        got_some = 1;
        if(s->parent)
        {
        if(!allow_pe)
            return error(p,
                 "PE end not allowed here in internal subset");
        if(s->entity->type == ET_external)
            p->external_pe_depth--;
        ParserPop(p);
        s = p->source;
        }
        else
        {
        unget(s);   /* leave the final EOE waiting to be read */
        return got_some;
        }
    }
    else if(is_xml_whitespace(c))
    {
        got_some = 1;
    }
    else if(c == '%')
    {
        /* this complication is needed for <!ENTITY % ...
           otherwise we could just assume it was a PE reference. */

        c = get(s); unget(s);
        if(c != XEOE && is_xml_namestart(c))
        {
        if(!allow_pe)
        {
            unget(s);   /* For error position */
            return error(p, 
                 "PE ref not allowed here in internal subset");
        }
        require(parse_reference(p, 1, 1, 1));
        s = p->source;
        if(s->entity->type == ET_external)
            p->external_pe_depth++;
        got_some = 1;
        }
        else
        {
        unget(s);
        return got_some;
        }
    }
    else
    {
        unget(s);
        return got_some;
    }
    }
}

static int expect(Parser p, int expected, const char8 *where)
{
    int c;
    InputSource s = p->source;

    c = get(s);
    if(c != expected)
    {
    unget(s);       /* For error position */
    return error(p, "Expected %s %s, but got %s",
             escape(expected), where, escape(c));
    }

    return 0;
}

/* 
 * Expects whitespace or the start or end of a PE.
 */

static int expect_dtd_whitespace(Parser p, const char8 *where)
{
    int r = skip_dtd_whitespace(p, p->external_pe_depth > 0);

    if(r < 0)
    return -1;

    if(r == 0)
    return error(p, "Expected whitespace %s", where);

    return 0;
}

static void clear_xbit(XBit xbit)
{
    xbit->type = XBIT_none;
    xbit->s1 = xbit->s2 = 0;
    xbit->S1 = xbit->S2 = 0;
    xbit->attributes = 0;
    xbit->element_definition = 0;
}

void FreeXBit(XBit xbit)
{
    Attribute a, b;

    if(xbit->S1) Free(xbit->S1);
    if(xbit->S2) Free(xbit->S2);
    if(xbit->type != XBIT_error && xbit->type != XBIT_warning && xbit->s1)
    Free(xbit->s1);
    if(xbit->s2) Free(xbit->s2);
    for(a = xbit->attributes; a; a = b)
    {
    b = a->next;
    if(a->value) Free(a->value);
    Free(a);
    }
    clear_xbit(xbit);
}

/* 
 * Returns 1 if the input matches string (and consume the input).
 * Otherwise returns 0 and leaves the input stream where it was.
 * Case-sensitivity depends on the CaseInsensitive flag.
 * A space character at end of string matches any (non-zero) amount of
 * whitespace; space are treated literally elsewhere.
 * Never reads beyond an end-of-line, except to consume
 * extra whitespace when the last character of string is a space.
 * Never reads beyond end-of-entity.
 */

static int looking_at(Parser p, const char8 *string)
{
    InputSource s = p->source;
    int c, d;
    int save = s->next;

    for(c = *string++; c; c = *string++)
    {
    if(at_eol(s))
        goto fail;      /* We would go over a line end */

    d = get(s);

    if(c == ' ' && *string == 0)
    {
        if(d == XEOE || !is_xml_whitespace(d))
        goto fail;
        skip_whitespace(s);
    }
    else
        if((ParserGetFlag(p, CaseInsensitive) &&
        Toupper(d) != Toupper(c)) ||
           (!ParserGetFlag(p, CaseInsensitive) && d != c))
        goto fail;
    }

    return 1;

fail:
    s->next = save;
    return 0;
}

static int parse_name(Parser p, const char8 *where)
{
    InputSource s = p->source;
    int c, i;

    c = get(s);
    if(c == XEOE || !is_xml_namestart(c))
    {
    unget(s);       /* For error position */
    error(p, "Expected name, but got %s %s", escape(c), where);
    return -1;
    }
    i = 1;

    while(c = get(s), (c != XEOE && is_xml_namechar(c)))
    i++;
    unget(s);

    p->name = s->line + s->next - i;
    p->namelen = i;

    return 0;
}

static int parse_nmtoken(Parser p, const char8 *where)
{
    InputSource s = p->source;
    int c, i=0;

    while(c = get(s), (c !=XEOE && is_xml_namechar(c)))
    i++;
    unget(s);

    if(i == 0)
    return error(p, "Expected nmtoken value, but got %s %s", 
             escape(c), where);

    p->name = s->line + s->next - i;
    p->namelen = i;

    return 0;
}

/* Escape a character for printing n an error message.  
   NB returns 5 static storage buffers in rotation. */

static const char8 *escape(int c)
{
    static char8 buf[5][15];
    static int bufnum=-1;

#if CHAR_SIZE == 8
    if(c != XEOE)
    c &= 0xff;
#endif

    bufnum = (bufnum + 1) % 5;

    if(c == XEOE)
    return "<EOE>";
    else if(c >= 33 && c <= 126)
    sprintf(buf[bufnum], "%c", c);
    else if(c == ' ')
    sprintf(buf[bufnum], "<space>");
    else
    sprintf(buf[bufnum], "<0x%x>", c);
    
    return buf[bufnum];
}

Parser NewParser(void)
{
    Parser p;

    if(ParserInit() == -1)
    return 0;

    p = Malloc(sizeof(*p));
    if(!p)
    return 0;
    p->state = PS_prolog1;
    p->document_entity = 0; /* Set at first ParserPush */
    p->have_dtd = 0;
    p->standalone = SDD_unspecified;
    p->flags = 0;
    p->source = 0;
    clear_xbit(&p->xbit);
#ifndef FOR_LT
    p->xbit.nchildren = 0;  /* These three should never be changed */
    p->xbit.children = 0;
    p->xbit.parent = 0;
#endif
    p->pbufsize = p->pbufnext = 0;
    p->pbuf = 0;
    p->peeked = 0;
    p->dtd = NewDtd();
    p->dtd_callback = p->warning_callback = 0;
    p->entity_opener = 0;
    p->callback_arg = 0;
    p->external_pe_depth = 0;

    p->element_stack = 0;
    p->element_stack_alloc = 0;
    p->element_depth = 0;

    ParserSetFlag(p, XMLPiEnd, 1);
    ParserSetFlag(p, XMLEmptyTagEnd, 1);
    ParserSetFlag(p, XMLPredefinedEntities, 1);
    ParserSetFlag(p, XMLExternalIDs, 1);
    ParserSetFlag(p, XMLMiscWFErrors, 1);
    ParserSetFlag(p, ErrorOnUnquotedAttributeValues, 1);
    ParserSetFlag(p, XMLLessThan, 1);
    ParserSetFlag(p, IgnoreEntities, 0);
    ParserSetFlag(p, ExpandGeneralEntities, 1);
    ParserSetFlag(p, ExpandCharacterEntities, 1);
    ParserSetFlag(p, NormaliseAttributeValues, 1);
    ParserSetFlag(p, WarnOnUndefinedElements, 1);
    ParserSetFlag(p, WarnOnUndefinedAttributes, 1);
    ParserSetFlag(p, WarnOnRedefinitions, 1);
    ParserSetFlag(p, TrustSDD, 1);
    ParserSetFlag(p, ReturnComments, 1);
    ParserSetFlag(p, CheckEndTagsMatch, 1);

    return p;
}

void FreeParser(Parser p)
{
    while (p->source)
    ParserPop(p);       /* Will close file */

    Free(p->pbuf);
    Free(p->element_stack);
    Free(p);
}

InputSource ParserRootSource(Parser p)
{
    InputSource s;

    for(s=p->source; s && s->parent; s = s->parent)
    ;

    return s;
}

Entity ParserRootEntity(Parser p)
{
    return ParserRootSource(p)->entity;
}

void ParserSetCallbackArg(Parser p, void *arg)
{
    p->callback_arg = arg;
}

void ParserSetDtdCallback(Parser p, CallbackProc cb)
{
    p->dtd_callback = cb;
}

void ParserSetWarningCallback(Parser p, CallbackProc cb)
{
    p->warning_callback = cb;
}

void ParserSetEntityOpener(Parser p, EntityOpenerProc opener)
{
    p->entity_opener = opener;
}

#ifndef FOR_LT

XBit ReadXTree(Parser p)
{
    XBit bit, tree, child;
    XBit *children;

    bit = ReadXBit(p);

    switch(bit->type)
    {
    case XBIT_error:
    return bit;

    case XBIT_start:
    if(!(tree = Malloc(sizeof(*tree))))
    {
        error(p, "System error");
        return &p->xbit;
    }
    *tree = *bit;
    while(1)
    {
        child = ReadXTree(p);
        switch(child->type)
        {
        case XBIT_error:
        FreeXTree(tree);
        return child;
        
        case XBIT_eof:
        FreeXTree(tree);
        {
            error(p, "EOF in element");
            return &p->xbit;
        }

        case XBIT_end:
        if(child->element_definition != tree->element_definition)
        {
            const Char *name1 = tree->element_definition->name,
                   *name2 = child->element_definition->name;
            FreeXTree(tree);
            FreeXTree(child);
            error(p, "Mismatched end tag: expected </%S>, got </%S>",
              name1, name2);
            return &p->xbit;
        }
        FreeXTree(child);
        return tree;

        default:
        children = Realloc(tree->children, 
                   (tree->nchildren + 1) * sizeof(XBit));
        if(!children)
        {
            FreeXTree(tree);
            FreeXTree(child);
            error(p, "System error");
            return &p->xbit;
        }
        child->parent = tree;
        children[tree->nchildren] = child;
        tree->nchildren++;
        tree->children = children;
        break;
        }
    }
    
    default:
    if(!(tree = Malloc(sizeof(*tree))))
    {
        error(p, "System error");
        return &p->xbit;
    }
    *tree = *bit;
    return tree;
    }
}

void FreeXTree(XBit tree)
{
    int i;

    for(i=0; i<tree->nchildren; i++)
    FreeXTree(tree->children[i]);

    Free(tree->children);

    FreeXBit(tree);

    if(tree->type == XBIT_error)
    /* error "trees" are always in the Parser structure, not malloced */
    return;

    Free(tree);
}

#endif /* (not) FOR_LT */

XBit ReadXBit(Parser p)
{
    if(p->peeked)
    p->peeked = 0;
    else
    parse(p);

    return &p->xbit;
}

XBit PeekXBit(Parser p)
{
    if(p->peeked)
    error(p, "Attempt to peek twice");
    else
    {
    parse(p);
    p->peeked = 1;
    }

    return &p->xbit;
}

int ParserPush(Parser p, InputSource source)
{
    if(!p->source && !p->document_entity)
    p->document_entity = source->entity;

    source->parent = p->source;
    p->source = source;

    if(source->entity->type == ET_internal)
    return 0;

    /* Look at first few bytes of external entities to guess encoding,
       then look for an XMLDecl or TextDecl.  */

    if(source->entity->encoding == CE_unknown) /* we might already know */
    determine_character_encoding(source);

#if CHAR_SIZE == 8
    if(!EncodingIsAsciiSuperset(source->entity->encoding))
    return error(p, "Unsupported character encoding %s",
             CharacterEncodingName[source->entity->encoding]);
#else
    if(source->entity->encoding == CE_unknown)
    return error(p, "Unknown character encoding");
#endif

    get(source); unget(source); /* To get the first line read */

    source->entity->ml_decl = ML_unspecified;
    if(looking_at(p, "<?NSL "))
    return process_nsl_decl(p);
    if(looking_at(p, "<?xml "))
    {
    require(process_xml_decl(p));
    if(source->entity == p->document_entity &&
       !source->entity->version_decl)
        return error(p, "XML declaration in document entity lacked "
                "version number");
    if(source->entity != p->document_entity &&
       source->entity->standalone_decl != SDD_unspecified)
        return error(p, "Standalone attribute not allowed except in "
                "document entity");
    return 0;
    }
    else if(!ParserGetFlag(p, XMLStrictWFErrors) && looking_at(p, "<?XML "))
    {
    warn(p, "Found <?XML instead of <?xml; switching to case-"
         "insensitive mode");
    ParserSetFlag(p, CaseInsensitive, 1);
    return process_xml_decl(p);
    }
    else
    return 0;
}

void ParserPop(Parser p)
{
    InputSource source;

    source = p->source;
    Fclose(source->file16);
    p->source = source->parent;

    if(source->entity->type == ET_external)
    Free(source->line);
    Free(source);
}

/* Returns true if the source is at EOE. If so, the EOE will have been read. */

static int at_eoe(InputSource s)
{
    if(!at_eol(s))
    return 0;
    if(s->seen_eoe || get_with_fill(s) == XEOE)
    return 1;
    unget(s);
    return 0;
}

/* Pops any sources that are at EOE.  Leaves source buffer with at least
   one character in it (except at EOF, where it leaves the EOE unread). */

static void pop_while_at_eoe(Parser p)
{
    while(1)
    {
    InputSource s = p->source;

    if(!at_eoe(s))
        return;
    if(!s->parent)
    {
        unget(s);
        return;
    }
    ParserPop(p);
    }
}

void ParserSetFlag(Parser p, ParserFlag flag, int value)
{
    if(value)
    p->flags |= (1 << flag);
    else
    p->flags &= ~(1 << flag);

    if(flag == XMLPredefinedEntities)
    {
    if(value)
        p->dtd->predefined_entities = xml_predefined_entities;
    else
        p->dtd->predefined_entities = 0;
    }
}

void ParserPerror(Parser p, XBit bit)
{
    int linenum, charnum;
    InputSource s;

    Fprintf(Stderr, "%s: %s\n", 
        bit->type == XBIT_error ? "Error" : "Warning", 
        bit->error_message);


    for(s=p->source; s; s=s->parent)
    {
    if(s->entity->name)
        Fprintf(Stderr, " in entity \"%S\"", s->entity->name);
    else
        Fprintf(Stderr, " in unnamed entity");

    switch(SourceLineAndChar(s, &linenum, &charnum))
    {
    case 1:
        Fprintf(Stderr, " at line %d char %d of", linenum+1, charnum+1);
        break;
    case 0:
        Fprintf(Stderr, " defined at line %d char %d of",
            linenum+1, charnum+1);
        break;
    case -1:
        Fprintf(Stderr, " defined in");
        break;
    }

    Fprintf(Stderr, " %s\n", EntityDescription(s->entity));
    }
}


static int parse(Parser p)
{
    int c;
    InputSource s;

    if(p->state == PS_end || p->state == PS_error)
    {
    /* After an error or EOF, just keep returning EOF */
    p->xbit.type = XBIT_eof;
    return 0;
    }

    clear_xbit(&p->xbit);
    
    if(p->state <= PS_prolog2 || p->state == PS_epilog)
    skip_whitespace(p->source);

restart:
    pop_while_at_eoe(p);
    s = p->source;
    SourcePosition(s, &p->xbit.entity, &p->xbit.byte_offset);

    switch(c = get(s))
    {
    case XEOE:
    if(p->state != PS_epilog)
        return error(p, "Document ends too soon");
    p->state = PS_end;
    p->xbit.type = XBIT_eof;
    return 0;
    case '<':
    return parse_markup(p);
    case '&':
    if(ParserGetFlag(p, IgnoreEntities))
        goto pcdata;
    if(p->state <= PS_prolog2)
        return error(p, "Entity reference not allowed in prolog");
    if(looking_at(p, "#"))
    {
        /* a character reference - go back and parse as pcdata */
        unget(s);
        goto pcdata;
    }
    if(ParserGetFlag(p, ExpandGeneralEntities))
    {
        /* an entity reference - push it and start again */
        require(parse_reference(p, 0, 1, 1));
        goto restart;
    }
    /* not expanding general entities, so treat as pcdata */
    goto pcdata;
    default:
    pcdata:
    unget(s);
    return parse_pcdata(p);
    }
}

/* Called after reading '<' */

static int parse_markup(Parser p)
{
    InputSource s = p->source;
    int c = get(s);

    switch(c)
    {
    case '!':
    if(looking_at(p, "--"))
    {
        if(ParserGetFlag(p, ReturnComments))
        return parse_comment(p, 0);
        else
        {
        require(parse_comment(p, 1));
        return parse(p);
        }
    }
    else if(looking_at(p, "DOCTYPE "))
        return parse_dtd(p);
    else if(looking_at(p, "[CDATA["))
        return parse_cdata(p);
    else
        return error(p, "Syntax error after <!");
    
    case '/':
    return parse_endtag(p);

    case '?':
    return parse_pi(p);

    default:
    unget(s);
    if(!ParserGetFlag(p, XMLLessThan) && 
       (c == XEOE || !is_xml_namestart(c)))
    {
        /* In nSGML, recognise < as stago only if followed by namestart */

        unget(s);   /* put back the < */
        return parse_pcdata(p);
    }
    return parse_starttag(p);
    }
}

static int parse_endtag(Parser p)
{
    ElementDefinition def;
    Entity ent;

    p->xbit.type = XBIT_end;
    require(parse_name(p, "after </"));
    maybe_uppercase_name(p);

    if(ParserGetFlag(p, CheckEndTagsMatch))
    {
    if(p->element_depth <= 0)
        return error(p, "End tag </%.*S> outside of any element",
             p->namelen, p->name);

    ent = p->element_stack[--p->element_depth].entity;
    def = p->element_stack[p->element_depth].definition;

    if(p->namelen == def->namelen &&
       memcmp(p->name, def->name, p->namelen * sizeof(Char)) == 0)
        p->xbit.element_definition = def;
    else
        return error(p, "Mismatched end tag: expected </%S>, got </%.*S>",
             def->name, p->namelen, p->name);

    if(ent != p->source->entity)
        return error(p, "Element ends in different entity from that "
                "in which it starts");

    if(p->element_depth == 0)
        p->state = PS_epilog;
    }
    else
    {
    p->xbit.element_definition = FindElementN(p->dtd, p->name, p->namelen);
    if(!p->xbit.element_definition)
        return error(p, "End tag for unknown element %.*S", 
             p->namelen, p->name);
    }

    skip_whitespace(p->source);
    return expect(p, '>', "after name in end tag");
}

static int parse_starttag(Parser p)
{
    int c;

    if(p->state == PS_epilog && !ParserGetFlag(p, AllowMultipleElements))
    return error(p, "Document contains multiple elements");

    p->state = PS_body;

    require(parse_name(p, "after <"));
    maybe_uppercase_name(p);

    p->xbit.element_definition = FindElementN(p->dtd, p->name, p->namelen);
    if(!p->xbit.element_definition || p->xbit.element_definition->tentative)
    {
    if(p->have_dtd && ParserGetFlag(p, ErrorOnUndefinedElements))
        return error(p, "Start tag for undeclared element %.*S",
             p->namelen, p->name);
    if(p->have_dtd && ParserGetFlag(p, WarnOnUndefinedElements))
        warn(p, "Start tag for undeclared element %.*S; "
            "declaring it to have content ANY",
         p->namelen, p->name);
    if(p->xbit.element_definition)
        RedefineElement(p->xbit.element_definition, CT_any, 0);
    else
    {
        if(!(p->xbit.element_definition = 
         DefineElementN(p->dtd, p->name, p->namelen, CT_any, 0)))
        return error(p, "System error");
    }
    }

    while(1)
    {
    InputSource s = p->source;

    /* We could just do skip_whitespace here, but we will get a
       better error message if we look a bit closer. */

    c = get(s);
    if(c !=XEOE && is_xml_whitespace(c))
    {
        skip_whitespace(s);
        c = get(s);
    }
    else if(c != '>' &&
        !(ParserGetFlag(p, XMLEmptyTagEnd) && c == '/'))
    {
        unget(s);       /* For error position */
        return error(p, "Expected whitespace or tag end in start tag");
    }

    if(c == '>')
    {
        p->xbit.type = XBIT_start;
        break;
    }

    if((ParserGetFlag(p, XMLEmptyTagEnd)) && c == '/')
    {
        require(expect(p, '>', "after / in start tag"));
        p->xbit.type = XBIT_empty;
        break;
    }

    unget(s);

    require(parse_attribute(p));
    }

    if(ParserGetFlag(p, CheckEndTagsMatch))
    {
    if(p->xbit.type == XBIT_start)
    {
        if(p->element_depth == p->element_stack_alloc)
        {
        p->element_stack_alloc = 
            p->element_stack_alloc == 0 ? 20 :
                                          p->element_stack_alloc * 2;
        if(!(p->element_stack = 
             Realloc(p->element_stack,
            (p->element_stack_alloc * sizeof(*p->element_stack)))))
            return error(p, "System error");
        }
        p->element_stack[p->element_depth].definition =
        p->xbit.element_definition;
        p->element_stack[p->element_depth++].entity = p->source->entity;
    }
    else
        if(p->element_depth == 0)
        p->state = PS_epilog;
    }

    if(ParserGetFlag(p, ReturnDefaultedAttributes))
    {
    AttributeDefinition d;
    Attribute a;

    for(d=NextAttributeDefinition(p->xbit.element_definition, 0);
        d;
        d=NextAttributeDefinition(p->xbit.element_definition, d))
    {
        if(!d->default_value)
        continue;
        for(a=p->xbit.attributes; a; a=a->next)
        if(a->definition == d)
            break;
        if(!a)
        {
        if(!(a = Malloc(sizeof(*a))))
            return error(p, "System error");
        a->definition = d;
        if(!(a->value = Strdup(d->default_value)))
            return error(p, "System error");
        a->quoted = 1;
        a->next = p->xbit.attributes;
        p->xbit.attributes = a;
        }
    }   
    }

    return 0;
}

static int parse_attribute(Parser p)
{
    InputSource s = p->source;
    AttributeDefinition def;
    struct attribute *a;
    int c;

    require(parse_name(p, "for attribute"));
    maybe_uppercase_name(p);

    def = FindAttributeN(p->xbit.element_definition, p->name, p->namelen);
    if(!def)
    {
    if(p->have_dtd && ParserGetFlag(p, ErrorOnUndefinedAttributes))
        return error(p, "Undeclared attribute %.*S for element %S",
            p->namelen, p->name, p->xbit.element_definition->name);
    if(p->have_dtd && ParserGetFlag(p, WarnOnUndefinedAttributes))
        warn(p, "Undeclared attribute %.*S for element %S; "
            "declaring it as CDATA #IMPLIED",
         p->namelen, p->name, p->xbit.element_definition->name);
    if(!(def = DefineAttributeN(p->xbit.element_definition, 
                    p->name, p->namelen,
                    AT_cdata, 0, DT_implied, 0)))
        return error(p, "System error");
    }

    for(a = p->xbit.attributes; a; a = a->next)
    if(a->definition == def)
        return error(p, "Repeated attribute %.*S", p->namelen, p->name);

    if(!(a = Malloc(sizeof(*a))))
    return error(p, "System error");

    a->value = 0;       /* in case of error */
    a->next = p->xbit.attributes;
    p->xbit.attributes = a;
    a->definition = def;

    skip_whitespace(s);
    require(expect(p, '=', "after attribute name"));

    skip_whitespace(s);
    c = get(s);
    unget(s);
    switch(c)
    {
    case '"':
    case '\'':
    a->quoted = 1;
    require(parse_string(p, "in attribute value",
                 a->definition->type == AT_cdata ? LT_cdata_attr :
                                                   LT_tok_attr));
    a->value = p->pbuf;
    Consume(p->pbuf);
    break;
    default:
    if(ParserGetFlag(p, ErrorOnUnquotedAttributeValues))
        return error(p, "Value of attribute is unquoted");
    a->quoted = 0;
    require(parse_nmtoken(p, "in unquoted attribute value"));
    CopyName(a->value);
    break;
    }

    return 0;
}

static int transcribe(Parser p, int back, int count)
{
    ExpandBuf(p->pbuf, p->pbufnext + count);
    memcpy(p->pbuf + p->pbufnext,
       p->source->line + p->source->next - back,
       count * sizeof(Char));
    p->pbufnext += count;
    return 0;
}

/* Called after pushing back the first character of the pcdata */

static int parse_pcdata(Parser p)
{
    int count = 0;
    InputSource s;
    Char *buf;
    int next, buflen;

    if(p->state <= PS_prolog2)
    return error(p, "Character data not allowed in prolog");
    if(p->state == PS_epilog)
    return error(p, "Character data not allowed after body");

    s = p->source;
    buf = s->line;
    next = s->next;
    buflen = s->line_length;

    p->pbufnext = 0;
    
    while(1)
    {
    if(next == buflen)
    {
        s->next = next;
        if(count > 0)
        {
        require(transcribe(p, count, count));
        }
        count = 0;
        if(at_eoe(s))
        {
        if(!ParserGetFlag(p, MergePCData))
            goto done;
        else
            pop_while_at_eoe(p);
        }
        s = p->source;
        buf = s->line;
        next = s->next;
        buflen = s->line_length;
        if(next == buflen)
        goto done;  /* must be EOF */
    }

    switch(buf[next++])
    {
    case '<':
        if(!ParserGetFlag(p, XMLLessThan))
        {
        /* In nSGML, don't recognise < as markup unless it looks ok */
        if(next == buflen)
            goto deflt;
        if(buf[next] != '!' && buf[next] != '/' && buf[next] != '?' &&
           !is_xml_namestart(buf[next]))
            goto deflt;
        }
        s->next = next;
        if(count > 0)
        {
        require(transcribe(p, count+1, count));
        }
        count = 0;
        if(!ParserGetFlag(p, ReturnComments) && 
           buflen >= next + 3 &&
           buf[next] == '!' && buf[next+1] == '-' && buf[next+2] == '-')
        {
        s->next = next + 3;
        require(parse_comment(p, 1));
        buflen = s->line_length;
        next = s->next;
        }
        else
        {
        s->next = next-1;
        goto done;
        }
        break;
    case '&':
        if(ParserGetFlag(p, IgnoreEntities))
        goto deflt;
        if(!ParserGetFlag(p, MergePCData) &&
           (p->pbufnext > 0  || count > 0))
        {
        /* We're returning references as separate bits, and we've
         come to one, and we've already got some data to return,
         so return what we've got and get the reference next time. */

        s->next = next-1;
        if(count > 0)
            {
            require(transcribe(p, count, count));
            }
        goto done;
        }
        if(buflen >= next+1 && buf[next] == '#')
        {
        /* It's a character reference */

        s->next = next+1;
        if(count > 0)
            {
            require(transcribe(p, count+2, count));
            }
        count = 0;
        require(parse_character_reference(p,
                   ParserGetFlag(p, ExpandCharacterEntities)));
        next = s->next;

        if(!ParserGetFlag(p, MergePCData))
            goto done;
        }
        else
        {
        /* It's a general entity reference */

        s->next = next;
        if(count > 0)
            {
            require(transcribe(p, count+1, count));
            }
        count = 0;
        require(parse_reference(p, 0, 
                       ParserGetFlag(p, ExpandGeneralEntities),
                    1));
        s = p->source;
        buf = s->line;
        buflen = s->line_length;
        next = s->next;

        if(!ParserGetFlag(p, MergePCData))
            goto done;
        }
        break;
    case ']':
        if(ParserGetFlag(p, XMLMiscWFErrors) &&
           buflen >= next + 2 &&
           buf[next] == ']' && buf[next+1] == '>')
        return error(p, "Illegal character sequence ']]>' in pcdata");
        /* fall through */
    default:
    deflt:
        count++;
        break;
    }
    }
    
  done:
    p->pbuf[p->pbufnext++] = 0;
    p->xbit.type = XBIT_pcdata;
    p->xbit.pcdata_chars = p->pbuf;
    Consume(p->pbuf);

    return 0;
}

/* Called after reading '<!--'.  Won't go over an entity end. */

static int parse_comment(Parser p, int skip)
{
    InputSource s = p->source;
    int c, c1=0, c2=0;
    int count = 0;
    
    if(!skip)
    p->pbufnext = 0;

    while((c = get(s)) != XEOE)
    {
    count++;
    if(c1 == '-' && c2 == '-')
    {
        if(c == '>')
        break;
        unget(s);       /* For error position */
        return error(p, "-- in comment");
    }
        
    if(at_eol(s))
    {
        if(!skip)
        {
        require(transcribe(p, count, count));
        }
        count = 0;
    }
    c2 = c1; c1 = c;
    }

    if(c == XEOE)
    return error(p, "EOE in comment");

    if(skip)
    return 0;

    require(transcribe(p, count, count-3));
    p->pbuf[p->pbufnext++] = 0;
    p->xbit.type = XBIT_comment;
    p->xbit.comment_chars = p->pbuf;
    Consume(p->pbuf);

    return 0;
}

static int parse_pi(Parser p)
{
    InputSource s = p->source;
    int c, c1=0;
    int count = 0;
    Char xml[] = {'x', 'm', 'l', 0};

    require(parse_name(p, "after <?"));
    CopyName(p->xbit.pi_name);

    p->pbufnext = 0;

    if(Strcasecmp(p->xbit.pi_name, xml) == 0)
    {
    if(ParserGetFlag(p, XMLStrictWFErrors))
        return error(p, "Misplaced or wrong-case xml declaration");
    else
        warn(p, "Misplaced or wrong-case xml declaration; treating as PI");
    }

    /* Empty PI? */

    if(looking_at(p, ParserGetFlag(p, XMLPiEnd) ? "?>" : ">"))
    {
    ExpandBuf(p->pbuf, 0);
    goto done;
    }

    /* If non-empty, must be white space after name */

    c = get(s);
    if(c == XEOE || !is_xml_whitespace(c))
    return error(p, "Expected whitespace after PI name");
    skip_whitespace(s);

    while((c = get(s)) != XEOE)
    {
    count++;
    if(c == '>' &&
       (!ParserGetFlag(p, XMLPiEnd) || c1 == '?'))
        break;
    if(at_eol(s))
    {
        require(transcribe(p, count, count));
        count = 0;
    }
    c1 = c;
    }

    if(c == XEOE)
    return error(p, "EOE in PI");

    require(transcribe(p, count, count-(ParserGetFlag(p, XMLPiEnd) ? 2 : 1)));
done:
    p->pbuf[p->pbufnext++] = 0;
    p->xbit.type = XBIT_pi;
    p->xbit.pi_chars = p->pbuf;
    Consume(p->pbuf);

    return 0;
}

static int parse_string(Parser p, const char8 *where, enum literal_type type)
{
    int c, quote;
    int count = 0;
    InputSource start_source, s;

    s = start_source = p->source;
    
    quote = get(s);
    if(quote != '\'' && quote != '"')
    {
    unget(s);       /* For error position */
    return error(p, "Expected quoted string %s, but got %s",
             where, escape(quote));
    }

    p->pbufnext = 0;

    while(1)
    {
    switch(c = get(s))
    {
    case '\r':
    case '\n':
    case '\t':
        if(type == LT_plain || type == LT_entity ||
           !ParserGetFlag(p, NormaliseAttributeValues))
        {
        count++;
        break;
        }
        if(count > 0)
        {
        require(transcribe(p, count+1, count));
        }
        count = 0;
        ExpandBuf(p->pbuf, p->pbufnext+1);
        p->pbuf[p->pbufnext++] = ' ';
        break;

    case '<':
        if((type == LT_tok_attr || type == LT_cdata_attr) &&
           ParserGetFlag(p, XMLMiscWFErrors))
        return error(p, "Illegal character '<' %s", where);
        count++;
        break;

    case XEOE:
        if(s == start_source)
        {
        return error(p, "Quoted string goes past entity end");
        }
        if(count > 0)
        {
        require(transcribe(p, count, count));
        }
        count = 0;
        ParserPop(p);
        s = p->source;
        break;

    case '%':
        if(type != LT_entity)
        {
        count++;
        break;
        }
        if(count > 0)
        {
        require(transcribe(p, count+1, count));
        }
        count = 0;
        if(p->external_pe_depth == 0)
        {
        unget(s);   /* For error position */
        return error(p, "PE ref not allowed here in internal subset");
        }
        require(parse_reference(p, 1, 1, 1));
        s = p->source;
        break;

    case '&':
        if(ParserGetFlag(p, IgnoreEntities))
        goto deflt;
        if(type == LT_plain)
        {
        count++;
        break;
        }

        if(count > 0)
        {
        require(transcribe(p, count+1, count));
        }
        count = 0;
        if(looking_at(p, "#"))
        require(parse_character_reference(p, 
                ParserGetFlag(p, ExpandCharacterEntities)));
        else
        {
        require(parse_reference(p, 0,
                       type != LT_entity &&
                       ParserGetFlag(p, ExpandGeneralEntities),
                       !ParserGetFlag(p, XMLMiscWFErrors)));
        s = p->source;
        }
        break;

    default:
    deflt:
        if(c == quote && p->source == start_source)
        goto done;
        count++;
    }

    if(at_eol(s) && count > 0)
    {
        require(transcribe(p, count, count));
        count = 0;
    }
    }

done:
    if(count > 0)
    require(transcribe(p, count+1, count));
    else
    ExpandBuf(p->pbuf, p->pbufnext+1);
    p->pbuf[p->pbufnext++] = 0;

    if(ParserGetFlag(p, NormaliseAttributeValues) && type == LT_tok_attr)
    {
    Char *old, *new;

    new = old = p->pbuf;

    /* Maybe skip leading whitespace */

    while(*old == ' ')
        old++;

    /* Translate whitespace to spaces, maybe compressing */

    for( ; *old; old++)
    {
        if(*old == ' ')
        {
        /* NB can't be at start because we skipped whitespace */
        if(type == LT_tok_attr && new[-1] == ' ')
            ;
        else
            *new++ = ' ';
        }
        else
        *new++ = *old;
    }

    /* Maybe trim trailing space (only one possible) */

    if(new > p->pbuf && new[-1] == ' ')
        new--;

    *new = 0;
    }

    return 0;
}

static int parse_dtd(Parser p)
{
    InputSource s = p->source;
    Entity parent = s->entity;
    Entity internal_part = 0, external_part = 0;
    Char *name;
    char8 *publicid = 0, *systemid = 0;
    struct xbit xbit;

    xbit = p->xbit;     /* copy start position */
    xbit.type = XBIT_dtd;

    require(parse_name(p, "for name in dtd"));
    CopyName(name);
    maybe_uppercase(p, name);

    skip_whitespace(s);

    require(parse_external_id(p, 0, &publicid, &systemid, 
                  ParserGetFlag(p, XMLExternalIDs),
                  ParserGetFlag(p, XMLExternalIDs)));

    if(systemid || publicid)
    {
    external_part = NewExternalEntity(0, publicid, systemid, 0, parent);
    if(!external_part)
    {
        Free(name);
        return error(p, "System error");
    }
    skip_whitespace(s);
    }

    if(looking_at(p, "["))
    {
    int line = s->line_number, cpos = s->next;

    require(read_markupdecls(p));
    skip_whitespace(s);
    internal_part = NewInternalEntity(0, p->pbuf, parent, line, cpos, 1);
    Consume(p->pbuf);
    if(!internal_part)
    {
        Free(name);
        FreeEntity(external_part);
        return error(p, "System error");
    }
    }

    require(expect(p, '>', "at end of dtd"));

    if(p->state == PS_prolog1)
    p->state = PS_prolog2;
    else
    {
    Free(name);
    FreeEntity(external_part);
    FreeEntity(internal_part);

    if(ParserGetFlag(p, XMLStrictWFErrors))
        return error(p, "Misplaced or repeated DOCTYPE declaration");

    warn(p, "Misplaced or repeated DOCTYPE declaration");
    /* Ignore it and return the next bit */
    return parse(p);
    }

    if(p->dtd->name)
    {
    Free(name);
    FreeEntity(external_part);
    FreeEntity(internal_part);

    /* This happens if we manually set the dtd */
    return parse(p);
    }

    p->dtd->name = name;
    p->dtd->internal_part = internal_part;
    p->dtd->external_part = external_part;

    if(ParserGetFlag(p, TrustSDD))
    {
    if(internal_part)
    {
        ParseDtd(p, internal_part);
        if(p->xbit.type == XBIT_error)
        return -1;
    }
    if(external_part && p->standalone != SDD_yes)
    {
        ParseDtd(p, external_part);
        if(p->xbit.type == XBIT_error)
        return -1;
    }
    }

    p->xbit = xbit;
    return 0;
}

static int read_markupdecls(Parser p)
{
    InputSource s = p->source;
    int depth=1;
    int c, d, hyphens=0;
    int count = 0;

    p->pbufnext = 0;

    while(1)
    {
    c = get(s);
    if(c == XEOE)
        return error(p, "EOE in DTD");
    if(c == '-')
        hyphens++;
    else
        hyphens = 0;

    count++;

    switch(c)
    {
    case ']':
        if(--depth == 0)
        {
        count--;    /* We don't want the final ']' */
        require(transcribe(p, count+1, count));
        p->pbuf[p->pbufnext++] = 0;
        return 0;
        }
        break;

    case '[':
        depth++;
        break;

    case '"':
    case '\'':
        while((d = get(s)) != XEOE)
        {
        count++;
        if(at_eol(s))
        {
            require(transcribe(p, count, count));
            count = 0;
        }
        if(d == c)
            break;
        }
        if(d == XEOE)
        return error(p, "EOE in DTD");
        break;

    case '-':
        if(hyphens < 2)
        break;
        hyphens = 0;
        while((d = get(s)) != XEOE)
        {
        count++;
        if(at_eol(s))
        {
            require(transcribe(p, count, count));
            count = 0;
        }
        if(d == '-')
            hyphens++;
        else
            hyphens = 0;
        if(hyphens == 2)
            break;
        }
        if(d == XEOE)
        return error(p, "EOE in DTD");
        hyphens = 0;
        break;

    default:
        break;
    }

    if(at_eol(s) && count > 0)
    {
        require(transcribe(p, count, count));
        count = 0;
    }
    }
}

static int process_nsl_decl(Parser p)
{
    InputSource s = p->source;
    int c, count = 0;

    s->entity->ml_decl = ML_nsl;

    /* The default character encoding for nSGML files is ascii-ash */
    if(s->entity->encoding == CE_UTF_8)
    s->entity->encoding = CE_unspecified_ascii_superset;

    /* Syntax is <?NSL DDB unquoted-filename 0> */

    if(!looking_at(p, "DDB "))
    return error(p, "Expected \"DDB\" in NSL declaration");

    while(c = get(s), !is_xml_whitespace(c))
    switch(c)
    {
    case XEOE:
        return error(p, "EOE in NSL declaration");

    case '>':
        return error(p, "Syntax error in NSL declaration");
        
    default:
        count++;
    }

    p->pbufnext = 0;
    require(transcribe(p, count+1, count));
    p->pbuf[p->pbufnext++] = 0;

    skip_whitespace(s);
    if(!looking_at(p, "0>"))
    return error(p, "Expected \"0>\" at end of NSL declaration");

    if(!(s->entity->ddb_filename = strdup8(Chartochar8(p->pbuf))))
    return error(p, "System error");

    return 0;
}

static int process_xml_decl(Parser p)
{
    InputSource s = p->source;
    enum {None, V, E, S} which, last = None;
    Char *Value, *cp;
    char8 *value;
    CharacterEncoding enc = CE_unknown;
    Char c;

    s->entity->ml_decl = ML_xml;

    /* XXX Should save the string buffer because it may already be in use */

    while(!looking_at(p, "?>"))
    {
    if(looking_at(p, "version"))
        which = V;
    else if(looking_at(p, "encoding"))
        which = E;
    else if(looking_at(p, "standalone"))
        which = S;
    else
        return error(p, "Expected \"version\", \"encoding\" or "
             "\"standalone\" in XML declaration");

    if(which <= last)
    {
        if(ParserGetFlag(p, XMLStrictWFErrors))
        return error(p, "Repeated or misordered attributes "
                    "in XML declaration");
        warn(p, "Repeated or misordered attributes in XML declaration");
    }
    last = which;
    
    skip_whitespace(s);
    require(expect(p, '=', "after attribute name in XML declaration"));
    skip_whitespace(s);

    require(parse_string(p, "for attribute value in XML declaration",
                 LT_plain));

    maybe_uppercase(p, p->pbuf);
    Value = p->pbuf;

    if(which == E)
    {
        if(!is_ascii_alpha(Value[0]))
        return error(p, "Encoding name does not begin with letter");
        for(cp=Value+1; *cp; cp++)
        if(!is_ascii_alpha(*cp) && !is_ascii_digit(*cp) &&
           *cp != '.' && *cp != '_' && *cp != '-')
            return error(p, "Illegal character %s in encoding name",
                 escape(*cp));

        value = Chartochar8(Value);

        enc = FindEncoding(value);
        if(enc == CE_unknown)
        return error(p, "Unknown declared encoding %s", value);

        if(EncodingsCompatible(p->source->entity->encoding, enc, &enc))
        {
#if CHAR_SIZE == 8
        /* We ignore the declared encoding in 8-bit mode,
           and treat it as a random ascii superset. */
#else
        p->source->entity->encoding = enc;
#endif
        }
        else
        return error(p, "Declared encoding %s is incompatible with %s "
                    "which was used to read it",
             CharacterEncodingName[enc],
             CharacterEncodingName[p->source->entity->encoding]);

        s->entity->encoding_decl = enc;
    }

    if(which == S)
    {
        value = Chartochar8(Value);

        if(str_maybecase_cmp8(p, value, "no") == 0)
        p->standalone = SDD_no;
        else if(str_maybecase_cmp8(p, value, "yes") == 0)
        p->standalone = SDD_yes;
        else
        return error(p, "Expected \"yes\" or \"no\" "
                    "for standalone in XML declaration");

        s->entity->standalone_decl = p->standalone;
    }

    if(which == V)
    {
        for(cp=Value; *cp; cp++)
        if(!is_ascii_alpha(*cp) && !is_ascii_digit(*cp) &&
           *cp != '.' && *cp != '_' && *cp != '-' && *cp != ':')
            return error(p, "Illegal character %s in version number",
                 escape(*cp));

        if(!s->entity->version_decl)
        if(!(s->entity->version_decl = strdup8(Chartochar8(Value))))
            return error(p, "System error");
    }

    c = get(s);
    if(c == '?')
        unget(s);
    else if(!is_xml_whitespace(c))
        return error(p, "Expected whitespace or \"?>\" after attribute "
                "in XML declaration");
    skip_whitespace(s);
    }
    return 0;
}

static int parse_cdata(Parser p)
{
    InputSource s = p->source;
    int c, c1=0, c2=0;
    int count = 0;

    if(p->state <= PS_prolog2)
    return error(p, "Cdata section not allowed in prolog");
    if(p->state == PS_epilog)
    return error(p, "Cdata section not allowed after body");

    p->pbufnext = 0;

    while((c = get(s)) != XEOE)
    {
    count++;
    if(c == '>' && c1 == ']' && c2 == ']')
        break;
    if(at_eol(s))
    {
        require(transcribe(p, count, count));
        count = 0;
    }
    c2 = c1; c1 = c;
    }

    if(c == XEOE)
    return error(p, "EOE in CData section");

    require(transcribe(p, count, count-3));
    p->pbuf[p->pbufnext++] = 0;
    p->xbit.type = XBIT_cdsect;
    p->xbit.cdsect_chars = p->pbuf;
    Consume(p->pbuf);

    return 0;
}

XBit ParseDtd(Parser p, Entity e)
{
    InputSource source, save;

    if(e->type == ET_external && p->entity_opener)
    source = p->entity_opener(e, p->callback_arg);
    else
    source = EntityOpen(e);
    if(!source)
    {
    error(p, "Couldn't open dtd entity %s", EntityDescription(e));
    return &p->xbit;
    }

    save = p->source;
    p->source = 0;
    if(ParserPush(p, source) == -1)
    return &p->xbit;

    p->have_dtd = 1;

    p->external_pe_depth = (source->entity->type == ET_external);

    while(parse_markupdecl(p) == 0)
    ;

    p->external_pe_depth = 0;

    /* don't restore after error, so user can call ParserPerror */
    if(p->xbit.type != XBIT_error)
    {
    ParserPop(p);       /* to free the input source */
    p->source = save;
    }

    return &p->xbit;
}

/* 
 * Returns 0 normally, -1 if error, 1 at EOF.
 */
static int parse_markupdecl(Parser p)
{
    InputSource s;
    int c;
    int cur_line, cur_char;
    Entity cur_ent;

    if(p->state == PS_error)
    return error(p, "Attempt to continue reading DTD after error");

    clear_xbit(&p->xbit);

    require(skip_dtd_whitespace(p, 1)); /* allow PE even in internal subset */
    s = p->source;
    SourcePosition(s, &p->xbit.entity, &p->xbit.byte_offset);

    cur_ent = s->entity;
    cur_line = s->line_number;
    cur_char = s->next;

    c = get(s);
    switch(c)
    {
    case XEOE:
    p->xbit.type = XBIT_none;
    return 1;
    case '<':
    if(looking_at(p, "!ELEMENT"))
    {
        require(expect_dtd_whitespace(p, "after ELEMENT"));
        return parse_element_decl(p);
    }
    else if(looking_at(p, "!ATTLIST"))
    {
        require(expect_dtd_whitespace(p, "after ATTLIST"));
        return parse_attlist_decl(p);
    }
    else if(looking_at(p, "!ENTITY"))
    {
        require(expect_dtd_whitespace(p, "after ENTITY"));
        return parse_entity_decl(p, cur_ent, cur_line, cur_char);
    }
    else if(looking_at(p, "!NOTATION"))
    {
        require(expect_dtd_whitespace(p, "after NOTATION"));
        return parse_notation_decl(p);
    }
    else if(looking_at(p, "!["))
        return parse_conditional(p);
    else if(looking_at(p, "?"))
    {
        require(parse_pi(p));
        if(p->dtd_callback)
        p->dtd_callback(&p->xbit, p->callback_arg);
        else
        FreeXBit(&p->xbit);
        return 0;
    }
    else if(looking_at(p, "!--"))
    {
        if(ParserGetFlag(p, ReturnComments))
        {
        require(parse_comment(p, 0));
        if(p->dtd_callback)
            p->dtd_callback(&p->xbit, p->callback_arg);
        else
            FreeXBit(&p->xbit);
        return 0;
        }
        else
        return parse_comment(p, 1);
    }
    else
        return error(p, "Syntax error after < in dtd");
    default:
    unget(s);       /* For error position */
    return error(p, "Expected \"<\" in dtd, but got %s", escape(c));
    }
}

static int parse_reference(Parser p, int pe, int expand, int allow_external)
{
    Entity e;
    InputSource s;

    require(parse_name(p, pe ? "for parameter entity" : "for entity"));
    require(expect(p, ';', "after entity name"));

    if(!expand)
    return transcribe(p, 1 + p->namelen + 1, 1 + p->namelen + 1);

    e = FindEntityN(p->dtd, p->name, p->namelen, pe);
    if(!e)
    {
    Char *buf;
    Char *q;
    int i;

    if(pe || ParserGetFlag(p, ErrorOnUndefinedEntities))
        return error(p, "Undefined%s entity %.*S",
             pe ? " parameter" : "" ,
             p->namelen > 50 ? 50 : p->namelen, p->name);

    warn(p, "Undefined%s entity %.*S",
         pe ? " parameter" : "",
         p->namelen > 50 ? 50 : p->namelen, p->name);

    /* Fake a definition for it */

    buf = Malloc((5 + p->namelen + 1 + 1) * sizeof(Char));
    if(!buf)
        return error(p, "System error");
    q = buf;
    *q++ = '&'; *q++ = '#'; *q++ = '3'; *q++ = '8'; *q++ = ';';
    for(i=0; i<p->namelen; i++)
        *q++ = p->name[i];
    *q++ = ';';
    *q++ = 0;

    if(!(e = NewInternalEntityN(p->name, p->namelen, buf, 0, 0, 0, 0)))
        return error(p, "System error");
    if(!DefineEntity(p->dtd, e, 0))
        return error(p, "System error");
    }

    if(!allow_external && e->type == ET_external)
    return error(p, "Illegal reference to external entity");

    for(s = p->source; s; s = s->parent)
    if(s->entity == e)
        return error(p, "Recursive reference to entity \"%S\"", e->name);

    if(e->type == ET_external && p->entity_opener)
    s = p->entity_opener(e, p->callback_arg);
    else
    s = EntityOpen(e);
    if(!s)
    return error(p, "Couldn't open entity %S, %s",
             e->name, EntityDescription(e));
    
    require(ParserPush(p, s));

    return 0;
}

static int parse_character_reference(Parser p, int expand)
{
    InputSource s = p->source;
    int c, base = 10;
    int count = 0;
    unsigned int code = 0;
    Char *ch = s->line + s->next;

    if(looking_at(p, "x"))
    {
    ch++;
    base = 16;
    }

    while((c = get(s)) != ';')
    {
    if((c >= '0' && c <= '9') ||
       (base == 16 && ((c >= 'A' && c <= 'F') ||
               (c >= 'a' && c <= 'f'))))
        count++;
    else
    {
        unget(s);       /* For error position */
        return error(p, 
             "Illegal character %s in base-%d character reference",
             escape(c), base);
    }
    }

    if(!expand)
    return transcribe(p, 2 + (base == 16) + count + 1,
                 2 + (base == 16) + count + 1);

    while(count-- > 0)
    {
    c = *ch++;
    if(c >= '0' && c <= '9')
        code = code * base + (c - '0');
    else if(c >= 'A' && c <= 'F')
        code = code * base + 10 + (c - 'A');
    else
        code = code * base + 10 + (c - 'a');
    }

#if CHAR_SIZE == 8
    if(code > 255 || !is_xml_legal(code))
    {
    if(ParserGetFlag(p, ErrorOnBadCharacterEntities))
        return error(p, "0x%x is not a valid 8-bit XML character", code);
    else
        warn(p, "0x%x is not a valid 8-bit XML character; ignored", code);
    return 0;
    }
#else
    if(!is_xml_legal(code))
    {
    if(ParserGetFlag(p, ErrorOnBadCharacterEntities))
        return error(p, "0x%x is not a valid UTF-16 XML character", code);
    else
        warn(p, "0x%x is not a valid UTF-16 XML character; ignored", code);
    return 0;
    }

    if(code >= 0x10000)
    {
    /* Use surrogates */

    ExpandBuf(p->pbuf, p->pbufnext+2);
    code -= 0x10000;

    p->pbuf[p->pbufnext++] = (code >> 10) + 0xd800;
    p->pbuf[p->pbufnext++] = (code & 0x3ff) + 0xdc00;

    return 0;
    }
#endif

    ExpandBuf(p->pbuf, p->pbufnext+1);
    p->pbuf[p->pbufnext++] = code;

    return 0;
}

/* Called after reading '<!ELEMENT ' */

static int parse_element_decl(Parser p)
{
    Char *name;
    ContentType type;
    ElementDefinition def;
#if 1
    ContentParticle cp;
#else
    int c;
    Char pcdata[] = {'#','P','C','D','A','T','A',0};
#endif
    Char *content = 0;

    require(parse_name(p, "for name in element declaration"));
    CopyName(name);
    maybe_uppercase(p, name);

    require(expect_dtd_whitespace(p, "after name in element declaration"));

    if(looking_at(p, "EMPTY"))
    {
    type = CT_empty;
    content = 0;
    }
    else if(looking_at(p, "ANY"))
    {
    type = CT_any;
    content = 0;
    }
    else
#if 1
    if(looking_at(p, "("))
    {
    unget(p->source);
    if(!(cp = parse_cp(p)) ||
       check_content_decl(p, cp) < 0 ||
       !(content = stringify_cp(cp)))
    {
        FreeContentParticle(cp);
        Free(content);
        Free(name);
        return -1;
    }

    if(cp->type == CP_choice && cp->children[0]->type == CP_pcdata)
        type = CT_mixed;
    else
        type = CT_element;
    {
    }
    FreeContentParticle(cp); /* XXX */
    }
    else
    {
    Free(name);
    return error(p, "Expected \"EMPTY\", \"ANY\", or \"(\" after name in "
                "element declaration");
    }
#else
    {
    /* Don't really parse here... maybe improve sometime */

    int count = 0;

    p->pbufnext = 0;

    while((c = get(p->source)) != '>')
    {
        switch(c)
        {
        case XEOE:
        if(count > 0)
            require(transcribe(p, count, count));
        if(!p->source->parent)
            return error(p, "EOE in element declaration");
        ParserPop(p);
        count = 0;
        break;
        case '%':
        if(count > 0)
            require(transcribe(p, count+1, count));
        if(p->external_pe_depth == 0)
        {
            unget(p->source); /* For error position */
            return error(p,
                 "PE ref not allowed here in internal subset");
        }
        require(parse_reference(p, 1, 1, 1));
        count = 0;
        break;
        default:
        count++;
        if(at_eol(p->source))
        {
            require(transcribe(p, count, count));
            count = 0;
        }
        }
    }

    unget(p->source);
    require(transcribe(p, count, count));
    p->pbuf[p->pbufnext++] = 0;

    if(Strstr(p->pbuf, pcdata))
        type = CT_mixed;
    else
        type = CT_element;
    
    content = p->pbuf;
    Consume(p->pbuf);
    }
#endif
    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(expect(p, '>', "at end of element declaration"));

    if((def = FindElement(p->dtd, name)))
    {
    if(def->tentative)
        RedefineElement(def, type, content);
    else
    {
        Free(content);
        if(ParserGetFlag(p, WarnOnRedefinitions))
        warn(p, "Ignoring redeclaration of element %S", name);
    }
    }
    else
    if (!DefineElement(p->dtd, name, type, content)) {
        return error(p, "System error");
    };

    Free(name);

    return 0;
}

/* Content model parsing */

static ContentParticle parse_cp(Parser p)
{
    ContentParticle cp;

    if(looking_at(p, "("))
    {
    if(!(cp = parse_choice_or_seq(p)))
        return 0;
    }
    else if(looking_at(p, "#PCDATA"))
    {
    if(!(cp = Malloc(sizeof(*cp))))
    {
        error(p, "System error");
        return 0;
    }
    
    cp->type = CP_pcdata;
    }
    else
    {
    if(parse_name(p, "in content declaration") < 0)
        return 0;

    if(!(cp = Malloc(sizeof(*cp))))
    {
        error(p, "System error");
        return 0;
    }
    
    cp->type = CP_name;
    CopyName0(cp->name);
    }

    if(looking_at(p, "*"))
    cp->repetition = '*';
    else if(looking_at(p, "+"))
    cp->repetition = '+';
    else if(looking_at(p, "?"))
    cp->repetition = '?';
    else 
    cp->repetition = 0;

    return cp;
}

/* Called after '(' */

static ContentParticle parse_choice_or_seq(Parser p)
{
    ContentParticle cp, cp1;


    require0(skip_dtd_whitespace(p, p->external_pe_depth > 0));

    if(!(cp1 = parse_cp(p)))
    return 0;

    require0(skip_dtd_whitespace(p, p->external_pe_depth > 0));

    if(!(cp = parse_choice_or_seq_1(p, 1, 0)))
    FreeContentParticle(cp1);
    else
    cp->children[0] = cp1;

    return cp;
}

/* Called before '|', ',', or ')' */

static ContentParticle parse_choice_or_seq_1(Parser p, int nchildren, char sep)
{
    ContentParticle cp = 0, cp1;
    int nsep = get(p->source);

    if(nsep == ')')
    {
    /* We've reached the end */

    if(!(cp = Malloc(sizeof(*cp))) ||
       !(cp->children = Malloc(nchildren * sizeof(cp))))
    {
        Free(cp);
        error(p, "System error");
        return 0;
    }

    /* The standard does not specify whether '(foo)' is a choice or a
       sequence.  We make it a choice so that (#PCDATA) comes out as
       a choice, like other mixed models. */

    cp->type = sep == ',' ? CP_seq : CP_choice;
    cp->nchildren = nchildren;

    return cp;
    }

    if(nsep != '|' && nsep != ',')
    {
    error(p, "Expected | or , or ) in content declaration, got %s",
          escape(nsep));
    return 0;
    }

    if(sep && nsep != sep)
    {
    error(p, "Content particle contains both | and ,");
    return 0;
    }

    require0(skip_dtd_whitespace(p, p->external_pe_depth > 0));

    if(!(cp1 = parse_cp(p)))
    return 0;

    require0(skip_dtd_whitespace(p, p->external_pe_depth > 0));

    if(!(cp = parse_choice_or_seq_1(p, nchildren+1, (char)nsep)))
    FreeContentParticle(cp1);
    else
    cp->children[nchildren] = cp1;

    return cp;
}

/* Check content particle matches Mixed or children */

static int check_content_decl(Parser p, ContentParticle cp)
{
    int i;

    if(cp->type == CP_choice && cp->children[0]->type == CP_pcdata)
    {
    for(i=1; i<cp->nchildren; i++)
        if(cp->children[i]->type != CP_name)
        return error(p, "Invalid mixed content declaration");

    if(cp->repetition != '*' &&
       !(cp->nchildren == 1 && cp->repetition == 0))
        return error(p, "Invalid mixed content declaration");

    return 0;
    }
    else
    return check_content_decl_1(p, cp);
}

static int check_content_decl_1(Parser p, ContentParticle cp)
{
    int i;

    switch(cp->type)
    {
    case CP_pcdata:
    return error(p, "Misplaced #PCDATA in content declaration");
    case CP_seq:
    case CP_choice:
    for(i=0; i<cp->nchildren; i++)
        if(check_content_decl_1(p, cp->children[i]) < 0)
        return -1;
    return 0;
    default:
    return 0;
    }
}

/* Reconstruct the content model as a string */

static Char *stringify_cp(ContentParticle cp)
{
    int size = size_cp(cp);
    Char *s;
    FILE16 *f;

    if(!(s = Malloc((size+1) * sizeof(Char))) || 
       !(f = MakeFILE16FromString(s, (size + 1) * sizeof(Char), "w")))
    {
    Free(s);
    return 0;
    }

    print_cp(cp, f);
    s[size] = 0;

    Fclose(f);

    return s;
}

static void print_cp(ContentParticle cp, FILE16 *f)
{
    int i;

    switch(cp->type)
    {
    case CP_pcdata:
    Fprintf(f, "#PCDATA");
    break;
    case CP_name:
    Fprintf(f, "%S", cp->name);
    break;
    case CP_seq:
    case CP_choice:
    Fprintf(f, "(");
    for(i=0; i<cp->nchildren; i++)
    {
        if(i != 0)
        Fprintf(f, cp->type == CP_seq ? "," : "|");
        print_cp(cp->children[i], f);
    }
    Fprintf(f, ")");
    break;
    }

    if(cp->repetition)
    Fprintf(f, "%c", cp->repetition);
}

static int size_cp(ContentParticle cp)
{
    int i, s;

    switch(cp->type)
    {
    case CP_pcdata:
    s = 7;
    break;
    case CP_name:
    s = Strlen(cp->name);
    break;
    default:
    s = 2;
    for(i=0; i<cp->nchildren; i++)
    {
        if(i != 0)
        s++;
        s += size_cp(cp->children[i]);
    }
    break;
    }

    if(cp->repetition)
    s++;

    return s;
}

void FreeContentParticle(ContentParticle cp)
{
    int i;

    if(!cp)
    return;

    switch(cp->type)
    {
    case CP_pcdata:
    break;
    case CP_name:
    Free(cp->name);
    break;
    case CP_seq:
    case CP_choice:
    for(i=0; i<cp->nchildren; i++)
        FreeContentParticle(cp->children[i]);
    Free(cp->children);
    break;
    }

    Free(cp);
}

/* Called after reading '<!ATTLIST ' */

static int parse_attlist_decl(Parser p)
{
    Char *name;
    ElementDefinition element;
    AttributeType type;
    DefaultType default_type;
    Char **allowed_values, *t;
    Char *default_value;
    int nvalues, i;

    require(parse_name(p, "for name in attlist declaration"));
    CopyName(name);
    maybe_uppercase(p, name);

    if(!(element = FindElement(p->dtd, name)))
    {
    if(!(element = TentativelyDefineElement(p->dtd, name)))
        return error(p, "System error");
    }
    Free(name);

    require(expect_dtd_whitespace(p,
                    "after element name in attlist declaration"));

    while(!looking_at(p, ">"))
    {
    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(parse_name(p, "for attribute in attlist declaration"));
    CopyName(name);
    maybe_uppercase(p, name);
    
    require(expect_dtd_whitespace(p, "after name in attlist declaration"));

    if(looking_at(p, "CDATA"))
        type = AT_cdata;
    else if(looking_at(p, "IDREFS"))
        type = AT_idrefs;
    else if(looking_at(p, "IDREF"))
        type = AT_idref;
    else if(looking_at(p, "ID"))
        type = AT_id;
    else if(looking_at(p, "ENTITIES"))
        type = AT_entities;
    else if(looking_at(p, "ENTITY"))
        type = AT_entity;
    else if(looking_at(p, "NMTOKENS"))
        type = AT_nmtokens;
    else if(looking_at(p, "NMTOKEN"))
        type = AT_nmtoken;
    else if(looking_at(p, "NOTATION"))
        type = AT_notation;
    else
        type = AT_enumeration;

    if(type != AT_enumeration)
    {
        require(expect_dtd_whitespace(p, "after attribute type"));
        }

    if(type == AT_notation || type == AT_enumeration)
    {
        require(expect(p, '(', 
               "or keyword for type in attlist declaration"));

        nvalues = 0;
        p->pbufnext = 0;
        do
        {
        require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
        if(type == AT_notation)
            require(parse_name(p,
                   "for notation value in attlist declaration"));
        else
            require(parse_nmtoken(p,
                   "for enumerated value in attlist declaration"));
        maybe_uppercase_name(p);
        ExpandBuf(p->pbuf, p->pbufnext + p->namelen + 1);
        memcpy(p->pbuf+p->pbufnext, 
               p->name,
               p->namelen * sizeof(Char));
        p->pbuf[p->pbufnext + p->namelen] = 0;
        p->pbufnext += (p->namelen + 1);
        nvalues++;
        require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
        }
        while(looking_at(p, "|"));

        require(expect(p, ')',
          "at end of enumerated value list in attlist declaration"));
        require(expect_dtd_whitespace(p, "after enumerated value list "
                         "in attlist declaration"));

        allowed_values = Malloc((nvalues+1)*sizeof(Char *));
        if(!allowed_values)
        return error(p, "System error");
        for(i=0, t=p->pbuf; i<nvalues; i++)
        {
        allowed_values[i] = t;
        while(*t++)
            ;
        }
        allowed_values[nvalues] = 0;

        Consume(p->pbuf);
    }
    else
        allowed_values = 0;

    if(looking_at(p, "#REQUIRED"))
        default_type = DT_required;
    else if(looking_at(p, "#IMPLIED"))
        default_type = DT_implied;
    else if(looking_at(p, "#FIXED"))
    {
        default_type = DT_fixed;
        require(expect_dtd_whitespace(p, "after #FIXED"));
    }
    else
        default_type = DT_none;

    if(default_type == DT_fixed || default_type == DT_none)
    {
        require(parse_string(p,
                 "for default value in attlist declaration",
                 type == AT_cdata ? LT_cdata_attr :
                                    LT_tok_attr));
        default_value = p->pbuf;
        Consume(p->pbuf);
        if(type != AT_cdata && type != AT_entity && type != AT_entities)
        maybe_uppercase(p, default_value);
    }
    else
        default_value = 0;

    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));

    if(FindAttribute(element, name))
    {
        if(ParserGetFlag(p, WarnOnRedefinitions))
        warn(p, "Ignoring redeclaration of attribute %S", name);
        if(allowed_values)
        {
        Free(allowed_values[0]);
        Free(allowed_values);
        }
        if(default_value)
        Free(default_value);
    }
    else
        if(!DefineAttribute(element, name, type, allowed_values,
                default_type, default_value))
        return error(p, "System error");

    Free(name);
    }
    
    return 0;
}

/* Used for external dtd part, entity definitions and notation definitions. */
/* NB PE references are not allowed here (why not?) */

static int parse_external_id(Parser p, int required,
                 char8 **publicid, char8 **systemid,
                 int preq, int sreq)
{
    InputSource s = p->source;
    int c;
    Char *cp;

    *publicid = 0;
    *systemid = 0;

    if(looking_at(p, "SYSTEM"))
    {
    if(!sreq)
    {
        skip_whitespace(s);
        c = get(s); unget(s);
        if(c != '"' && c != '\'')
        return 0;
    }
    else
        require(expect_dtd_whitespace(p, "after SYSTEM"));

    require(parse_string(p, "for system ID", LT_plain));
    if(!(*systemid = strdup8(Chartochar8(p->pbuf))))
        return error(p, "System error");
    }
    else if(looking_at(p, "PUBLIC"))
    {
    if(!preq && !sreq)
    {
        skip_whitespace(s);
        c = get(s); unget(s);
        if(c != '"' && c != '\'')
        return 0;
    }
    else
        require(expect_dtd_whitespace(p, "after PUBLIC"));

    require(parse_string(p, "for public ID", LT_plain));

    for(cp=p->pbuf; *cp; cp++)
        if(!is_ascii_alpha(*cp) && !is_ascii_digit(*cp) &&
           strchr8("-'()+,./:=?;!*#@$_% \r\n", *cp) == 0)
        return error(p, "Illegal character %s in public id",
                 escape(*cp));

    if(!(*publicid = strdup8(Chartochar8(p->pbuf))))
        return error(p, "System error");

    if(!sreq)
    {
        skip_whitespace(s);
        c = get(s); unget(s);
        if(c != '"' && c != '\'')
        return 0;
    }
    else
        require(expect_dtd_whitespace(p, "after public id"));

    require(parse_string(p, "for system ID", LT_plain));
    if(!(*systemid = strdup8(Chartochar8(p->pbuf))))
        return error(p, "System error");
    }
    else if(required)
    return error(p, "Missing or invalid external ID");

    return 0;
}

/* Called after reading '<!ENTITY ' */

static int parse_entity_decl(Parser p, Entity ent, int line, int chpos)
{
    Entity e, old;
    int pe, t;
    Char *name;

    pe = looking_at(p, "%");    /* If it were a PE ref, we would
                   already have pushed it */

    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(parse_name(p, "for name in entity declaration"));
    CopyName(name);

    require(expect_dtd_whitespace(p, "after name in entity declaration"));

    if(looking_at(p, "'") || looking_at(p, "\""))
    {
    Char *value;

    unget(p->source);
    require(parse_string(p, "for value in entity declaration", LT_entity));
    value = p->pbuf;
    Consume(p->pbuf);

    if(!(e = NewInternalEntity(name, value, ent, line, chpos, 0)))
        return error(p, "System error");
    }
    else
    {
    char8 *publicid, *systemid;
    NotationDefinition notation = 0;

    require(parse_external_id(p, 1, &publicid, &systemid, 1, 1));

    require((t = skip_dtd_whitespace(p, p->external_pe_depth > 0)));
    if(looking_at(p, "NDATA"))
    {
        if(t == 0)
        return error(p, "Whitespace missing before NDATA");
        if(pe)
        return error(p, "NDATA not allowed for parameter entity");
        require(expect_dtd_whitespace(p, "after NDATA"));
        require(parse_name(p, "for notation name in entity declaration"));
        maybe_uppercase_name(p);
        notation = FindNotationN(p->dtd, p->name, p->namelen);
        if(!notation)
        {
        notation =
            TentativelyDefineNotationN(p->dtd, p->name, p->namelen);
        if(!notation)
            return error(p, "System error");
        }
    }

    if(!(e = NewExternalEntity(name, publicid, systemid, notation, ent)))
        return error(p, "System error");
    }

    Free(name);

    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(expect(p, '>', "at end of entity declaration"));

    if((old = FindEntity(p->dtd, e->name, pe)) &&
       old->parent != xml_builtin_entity)
    {
    if(ParserGetFlag(p, WarnOnRedefinitions))
        warn(p, "Ignoring redefinition of%s entity %S",
         pe ? " parameter" : "", e->name);
    }
    else
    if(!DefineEntity(p->dtd, e, pe))
        return error(p, "System error");

    return 0;
}

/* Called after reading '<!NOTATION ' */

static int parse_notation_decl(Parser p)
{
    Char *name;
    char8 *publicid, *systemid;
    NotationDefinition def;

    require(parse_name(p, "for name in notation declaration"));
    CopyName(name);
    maybe_uppercase(p, name);

    require(expect_dtd_whitespace(p, "after name in notation declaration"));
    
    require(parse_external_id(p, 1, &publicid, &systemid, 1, 0));

    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(expect(p, '>', "at end of notation declaration"));

    if((def = FindNotation(p->dtd, name)))
    {
    if(def->tentative)
        RedefineNotation(def, publicid, systemid);
    else
        if(ParserGetFlag(p, WarnOnRedefinitions))
        {
        warn(p, "Ignoring redefinition of notation %S", name);
        if(publicid) Free(publicid);
        if(systemid) Free(systemid);
        }
    }
    else
    {
    if(!DefineNotation(p->dtd, name, publicid, systemid))
        return error(p, "System error");
    }

    Free(name);

    return 0;
}

static int parse_conditional(Parser p)
{
    int depth=1;

    if(p->external_pe_depth == 0)
    return error(p, "Conditional section not allowed in internal subset");

    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    if(looking_at(p, "INCLUDE"))
    {
    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(expect(p, '[', "at start of conditional section"));
    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    while(!looking_at(p, "]"))
    {
        switch(parse_markupdecl(p))
        {
        case 1:
        return error(p, "EOF in conditional section");
        case -1:
        return -1;
        }
        require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    }

    if(!looking_at(p, "]>"))
        return error(p, "]> required after ] in conditional section");
    }
    else if(looking_at(p, "IGNORE"))
    {
    /* Easy, because ]]> not even allowed in strings! */

    require(skip_dtd_whitespace(p, p->external_pe_depth > 0));
    require(expect(p, '[', "at start of conditional section"));

    while(depth > 0)
    {
        switch(get(p->source))
        {
        case XEOE:
        if(p->source->parent)
            ParserPop(p);
        else
            return error(p, "EOE in ignored conditional section");
        break;
        case '<':
        if(looking_at(p, "!["))
            depth++;
        break;
        case ']':
        if(looking_at(p, "]>"))
            depth--;
        }
    }
    }
    else
    return error(p, "INCLUDE or IGNORE required in conditional section");

    return 0;
}

static void maybe_uppercase(Parser p, Char *s)
{
    if(ParserGetFlag(p, CaseInsensitive))
    while(*s)
    {
        *s = Toupper(*s);
        s++;
    }
}

static void maybe_uppercase_name(Parser p)
{
    int i;

    if(ParserGetFlag(p, CaseInsensitive))
    for(i=0; i<p->namelen; i++)
        p->name[i] = Toupper(p->name[i]);
}

static int str_maybecase_cmp8(Parser p, const char8 *a, const char8 *b)
{
    return
    ParserGetFlag(p, CaseInsensitive) ? strcasecmp8(a, b) : strcmp8(a, b);
}

static int is_ascii_alpha(int c)
{
    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}

static int is_ascii_digit(int c)
{
    return c >= '0' && c <= '9';
}

/* Error handling */

static void verror(XBit bit, const char8 *format, va_list args)
{
    /* yuk, but we don't want to fail if we can't allocate */
    static char8 message[400];

    /* Print message before freeing xbit, so we can print data from it */
    Vsprintf(message, CE_ISO_8859_1, format, args);

    FreeXBit(bit);
    bit->type = XBIT_error;
    bit->error_message = message;
}

static int error(Parser p, const char8 *format, ...)
{
    va_list args;

    va_start(args, format);
    verror(&p->xbit, format, args);

    p->state = PS_error;

    return -1;
}

static void warn(Parser p, const char8 *format, ...)
{
    va_list args;
    static struct xbit bit;

    va_start(args, format);
    verror(&bit, format, args);

    bit.type = XBIT_warning;

    if(p->warning_callback)
    p->warning_callback(&bit, p->callback_arg);
    else
    ParserPerror(p, &bit);
}