ezxml.c

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//==========================================================================
//
//      ezxml.h
//
//      Simple XML parser
//
//==========================================================================
//####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 2005 eCosCentric Ltd
//
// eCos is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 or (at your option) any later version.
//
// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with eCos; if not, write to the Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
//
// As a special exception, if other files instantiate templates or use macros
// or inline functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
// by itself cause the resulting work to be covered by the GNU General Public
// License. However the source code for this file must still be made available
// in accordance with section (3) of the GNU General Public License.
//
// This exception does not invalidate any other reasons why a work based on
// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####ECOSGPLCOPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    Aaron Voisine
// Contributors: Matt Jerdonek
// Date:         2005-01-31
// Purpose:      
// Description:  
//              
// This code is part of eCos (tm).
//
//####DESCRIPTIONEND####
//
//==========================================================================

/* ezxml.c
 *
 * Copyright 2004, 2005 Aaron Voisine <[e-mail]>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS 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.
 */

#define EZXML_NOMMAP // no mmap on eCos

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/types.h>
#ifndef EZXML_NOMMAP
#include <sys/mman.h>
#endif // EZXML_NOMMAP
#include <sys/stat.h>
#include "ezxml.h"

#include <pkgconf/system.h>

#define EZXML_WS   "\t\r\n "  // whitespace
#define EZXML_ERRL 128        // maximum error string length

typedef struct ezxml_root *ezxml_root_t;
struct ezxml_root {       // additional data for the root tag
    struct ezxml xml;     // is a super-struct built on top of ezxml struct
    ezxml_t cur;          // current xml tree insertion point
    char *m;              // original xml string
    size_t len;           // length of allocated memory for mmap, -1 for malloc
    char *u;              // UTF-8 conversion of string if original was UTF-16
    char *s;              // start of work area
    char *e;              // end of work area
    char **ent;           // general entities (ampersand sequences)
    char ***attr;         // default attributes
    char ***pi;           // processing instructions
    short standalone;     // non-zero if <?xml standalone="yes"?>
    char err[EZXML_ERRL]; // error string
};

char *EZXML_NIL[] = { NULL }; // empty, null terminated array of strings

// returns the first child tag with the given name or NULL if not found
ezxml_t ezxml_child(ezxml_t xml, const char *name)
{
    xml = (xml) ? xml->child : NULL;
    while (xml && strcmp(name, xml->name)) xml = xml->sibling;
    return xml;
}

// returns the Nth tag with the same name in the same subsection or NULL if not
// found
ezxml_t ezxml_idx(ezxml_t xml, int idx)
{
    for (; xml && idx; idx--) xml = xml->next;
    return xml;
}

// returns the value of the requested tag attribute or NULL if not found
const char *ezxml_attr(ezxml_t xml, const char *attr)
{
    int i = 0, j = 1;
    ezxml_root_t root = (ezxml_root_t)xml;

    if (! xml || ! xml->attr) return NULL;
    while (xml->attr[i] && strcmp(attr, xml->attr[i])) i += 2;
    if (xml->attr[i]) return xml->attr[i + 1]; // found attribute

    while (root->xml.parent) root = (ezxml_root_t)root->xml.parent; // root tag
    for (i = 0; root->attr[i] && strcmp(xml->name, root->attr[i][0]); i++);
    if (! root->attr[i]) return NULL; // no matching default attributes
    while (root->attr[i][j] && strcmp(attr, root->attr[i][j])) j += 3;
    return (root->attr[i][j]) ? root->attr[i][j + 1] : NULL; // found default
}

// same as ezxml_get but takes an already initialized va_list
ezxml_t ezxml_vget(ezxml_t xml, va_list ap)
{
    char *name = va_arg(ap, char *);
    int idx = -1;

    if (name && *name) {
        idx = va_arg(ap, int);    
        xml = ezxml_child(xml, name);
    }
    return (idx < 0) ? xml : ezxml_vget(ezxml_idx(xml, idx), ap);
}

// Traverses the xml tree to retrieve a specific subtag. Takes a variable
// length list of tag names and indexes. The argument list must be terminated
// by either an index of -1 or an empty string tag name. Example: 
// title = ezxml_get(library, "shelf", 0, "book", 2, "title", -1);
// This retrieves the title of the 3rd book on the 1st shelf of library.
// Returns NULL if not found.
ezxml_t ezxml_get(ezxml_t xml, ...)
{
    va_list ap;
    ezxml_t r;

    va_start(ap, xml);
    r = ezxml_vget(xml, ap);
    va_end(ap);
    return r;
}

// returns a null terminated array of processing instructions for the given
// target
const char **ezxml_pi(ezxml_t xml, const char *target)
{
    ezxml_root_t root = (ezxml_root_t)xml;
    int i = 0;

    if (! root) return (const char **)EZXML_NIL;
    while (root->xml.parent) root = (ezxml_root_t)root->xml.parent; // root tag
    while (root->pi[i] && strcmp(target, root->pi[i][0])) i++; // find target
    return (const char **)((root->pi[i]) ? root->pi[i] + 1 : EZXML_NIL);
}

// set an error string and return root
ezxml_t ezxml_err(ezxml_root_t root, char *s, const char *err, ...)
{
    va_list ap;
    int line = 1;
    char *t, fmt[EZXML_ERRL];
    
    for (t = root->s; t < s; t++) if (*t == '\n') line++;
    snprintf(fmt, EZXML_ERRL, "[error near line %d]: %s", line, err);

    va_start(ap, err);
    vsnprintf(root->err, EZXML_ERRL, fmt, ap);
    va_end(ap);

    return &root->xml;
}

// Recursively decodes entity and character references and normalizes new lines
// ent is a null terminated array of alternating entity names and values. set t
// to '&' for general entity decoding, '%' for parameter entity decoding, 'c'
// for cdata sections, ' ' for attribute normalization, or '*' for non-cdata
// attribute normalization. Returns s, or if the decoded string is longer than
// s, returns a malloced string that must be freed.
char *ezxml_decode(char *s, char **ent, char t)
{
    char *e, *r = s, *m = s;
    long b, c, d, l;

    for (; *s; s++) { // normalize line endings
        while (*s == '\r') {
            *(s++) = '\n';
            if (*s == '\n') memmove(s, (s + 1), strlen(s));
        }
    }
    
    for (s = r; ; ) {
        while (*s && *s != '&' && (*s != '%' || t != '%') && !isspace(*s)) s++;

        if (! *s) break;
        else if (t != 'c' && ! strncmp(s, "&#", 2)) { // character reference
            if (s[2] == 'x') c = strtol(s + 3, &e, 16); // base 16
            else c = strtol(s + 2, &e, 10); // base 10
            if (! c || *e != ';') { s++; continue; } // not a character ref

            if (c < 0x80) *(s++) = c; // US-ASCII subset
            else { // multi-byte UTF-8 sequence
                for (b = 0, d = c; d; d /= 2) b++; // number of bits in c
                b = (b - 2) / 5; // number of bytes in payload
                *(s++) = (0xFF << (7 - b)) | (c >> (6 * b)); // head
                while (b) *(s++) = 0x80 | ((c >> (6 * --b)) & 0x3F); // payload
            }

            memmove(s, strchr(s, ';') + 1, strlen(strchr(s, ';')));
        }
        else if ((*s == '&' && (t == '&' || t == ' ' || t == '*')) ||
                 (*s == '%' && t == '%')) { // entity reference
            for (b = 0; ent[b] && strncmp(s + 1, ent[b], strlen(ent[b]));
                 b += 2); // find entity in entity list

            if (ent[b++]) { // found a match
                if ((c = strlen(ent[b])) - 1 > (e = strchr(s, ';')) - s) {
                    l = (d = (s - r)) + c + strlen(e); // new length
                    r = (r == m) ? strcpy(malloc(l), r) : realloc(r, l);
                    e = strchr((s = r + d), ';'); // fix up pointers
                }

                memmove(s + c, e + 1, strlen(e)); // shift rest of string
                strncpy(s, ent[b], c); // copy in replacement text
            }
            else s++; // not a known entity
        }
        else if ((t == ' ' || t == '*') && isspace(*s)) *(s++) = ' ';
        else s++; // no decoding needed
    }

    if (t == '*') { // normalize spaces for non-cdata attributes
        for (s = r; *s; s++) {
            if ((l = strspn(s, " "))) memmove(s, s + l, strlen(s + l) + 1);
            while (*s && *s != ' ') s++;
        }
        if (--s >= r && *s == ' ') *s = '\0'; // trim any trailing space
    }
    return r;
}

// called when parser finds start of new tag
void ezxml_open_tag(ezxml_root_t root, char *name, char **attr)
{
    ezxml_t xml = root->cur;
    
    if (xml->name) xml = ezxml_add_child(xml, name, strlen(xml->txt));
    else xml->name = name; // first open tag

    xml->attr = attr;
    root->cur = xml; // update tag insertion point
}

// called when parser finds character content between open and closing tag
void ezxml_char_content(ezxml_root_t root, char *s, size_t len, char t)
{
    ezxml_t xml = root->cur;
    char *m = s;
    size_t l;

    if (! xml || ! xml->name || ! len) return; // sanity check

    s[len] = '\0'; // null terminate text (calling functions anticipate this)
    len = strlen(s = ezxml_decode(s, root->ent, t)) + 1;

    if (! *(xml->txt)) xml->txt = s; // initial character content
    else { // allocate our own memory and make a copy
        xml->txt = (xml->flags & EZXML_TXTM) // allocate some space
                   ? realloc(xml->txt, (l = strlen(xml->txt)) + len)
                   : strcpy(malloc((l = strlen(xml->txt)) + len), xml->txt);
        strcpy(xml->txt + l, s); // add new char content
        if (s != m) free(s); // free s if it was malloced by ezxml_decode()
    }

    if (xml->txt != m) ezxml_set_flag(xml, EZXML_TXTM);
}

// called when parser finds closing tag
ezxml_t ezxml_close_tag(ezxml_root_t root, char *name, char *s)
{
    if (! root->cur || ! root->cur->name || strcmp(name, root->cur->name))
        return ezxml_err(root, s, "unexpected closing tag </%s>", name);

    root->cur = root->cur->parent;
    return NULL;
}

// checks for circular entity references, returns non-zero if no circular
// references are found, zero otherwise
int ezxml_ent_ok(char *name, char *s, char **ent)
{
    int i;

    for (; ; s++) {
        while (*s && *s != '&') s++; // find next entity reference
        if (! *s) return 1;
        if (! strncmp(s + 1, name, strlen(name))) return 0; // circular ref.
        for (i = 0; ent[i] && strncmp(ent[i], s + 1, strlen(ent[i])); i += 2);
        if (ent[i] && ! ezxml_ent_ok(name, ent[i + 1], ent)) return 0;
    }
}

// called when the parser finds a processing instruction
void ezxml_proc_inst(ezxml_root_t root, char *s, size_t len)
{
    int i = 0, j = 1;
    char *target = s;

    s[len] = '\0'; // null terminate instruction
    if (*(s += strcspn(s, EZXML_WS))) {
        *s = '\0'; // null terminate target
        s += strspn(s + 1, EZXML_WS) + 1; // skip whitespace after target
    }

    if (! strcmp(target, "xml")) { // <?xml ... ?>
        if ((s = strstr(s, "standalone")) && ! strncmp(s + strspn(s + 10,
            EZXML_WS "='\"") + 10, "yes", 3)) root->standalone = 1;
        return;
    }