netsurf/render/libxml_binding.c
John Mark Bell 163ad56fce Rework html parser bindings to have a common API and reside in separate files for ease of reading.
Add error handling to hubbub binding.

svn path=/trunk/netsurf/; revision=5404
2008-09-23 02:19:50 +00:00

309 lines
8.3 KiB
C

/*
* Copyright 2007 James Bursa <bursa@users.sourceforge.net>
* Copyright 2008 John-Mark Bell <jmb@netsurf-browser.org>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf 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; version 2 of the License.
*
* NetSurf 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef WITH_HUBBUB
#include <stdbool.h>
#include <string.h>
#include <libxml/HTMLparser.h>
#include <libxml/HTMLtree.h>
#include <libxml/parser.h>
#include <libxml/parserInternals.h>
#include "render/parser_binding.h"
#include "utils/log.h"
#include "utils/talloc.h"
typedef struct libxml_ctx {
htmlParserCtxt *parser;
/** HTML parser encoding handler. */
xmlCharEncodingHandler *encoding_handler;
const char *encoding;
binding_encoding_source encoding_source;
bool getenc;
} libxml_ctx;
static bool set_parser_encoding(libxml_ctx *c, const char *encoding);
static const char *detect_encoding(const char **data, size_t *size);
void *binding_create_tree(void *arena, const char *charset)
{
libxml_ctx *ctx;
ctx = malloc(sizeof(libxml_ctx));
if (ctx == NULL)
return NULL;
ctx->parser = NULL;
ctx->encoding_handler = NULL;
ctx->encoding = charset;
ctx->encoding_source = ENCODING_SOURCE_HEADER;
ctx->getenc = true;
ctx->parser = htmlCreatePushParserCtxt(0, 0, "", 0, 0,
XML_CHAR_ENCODING_NONE);
if (ctx->parser == NULL) {
free(ctx);
return NULL;
}
if (ctx->encoding != NULL && !set_parser_encoding(ctx, charset)) {
if (ctx->parser->myDoc != NULL)
xmlFreeDoc(ctx->parser->myDoc);
htmlFreeParserCtxt(ctx->parser);
free(ctx);
return NULL;
}
return (void *) ctx;
}
void binding_destroy_tree(void *ctx)
{
libxml_ctx *c = (libxml_ctx *) ctx;
if (ctx == NULL)
return;
if (c->parser->myDoc != NULL)
xmlFreeDoc(c->parser->myDoc);
if (c->parser != NULL)
htmlFreeParserCtxt(c->parser);
c->parser = NULL;
c->encoding = NULL;
free(c);
}
binding_error binding_parse_chunk(void *ctx, const uint8_t *data, size_t len)
{
libxml_ctx *c = (libxml_ctx *) ctx;
if (c->getenc) {
/* No encoding was specified in the Content-Type header.
* Attempt to detect if the encoding is not 8-bit. If the
* encoding is 8-bit, leave the parser unchanged, so that it
* searches for a <meta http-equiv="content-type"
* content="text/html; charset=...">. */
const char *encoding;
encoding = detect_encoding((const char **) (void *) &data,
&len);
if (encoding) {
if (!set_parser_encoding(c, encoding))
return BINDING_NOMEM;
c->encoding = encoding;
c->encoding_source = ENCODING_SOURCE_DETECTED;
}
c->getenc = false;
/* The data we received may have solely consisted of a BOM.
* If so, it will have been stripped by html_detect_encoding.
* Therefore, we'll have nothing to do in that case. */
if (len == 0)
return BINDING_OK;
}
htmlParseChunk(c->parser, (const char *) data, len, 0);
/** \todo error handling */
if (!c->encoding && c->parser->input->encoding) {
/* The encoding was not in headers or detected,
* and the parser found a <meta http-equiv="content-type"
* content="text/html; charset=...">. */
/* However, if that encoding is non-ASCII-compatible,
* ignore it, as it can't possibly be correct */
if (strncasecmp((const char *) c->parser->input->encoding,
"UTF-16", 6) == 0 || /* UTF-16(LE|BE)? */
strncasecmp((const char *) c->parser->input->encoding,
"UTF-32", 6) == 0) { /* UTF-32(LE|BE)? */
c->encoding = "ISO-8859-1";
c->encoding_source = ENCODING_SOURCE_DETECTED;
} else {
c->encoding = (const char *) c->parser->input->encoding;
c->encoding_source = ENCODING_SOURCE_META;
}
if (!c->encoding)
return BINDING_NOMEM;
/* have the encoding; don't attempt to detect it */
c->getenc = false;
return BINDING_ENCODINGCHANGE;
}
return BINDING_OK;
}
binding_error binding_parse_completed(void *ctx)
{
libxml_ctx *c = (libxml_ctx *) ctx;
htmlParseChunk(c->parser, "", 0, 1);
/** \todo error handling */
return BINDING_OK;
}
const char *binding_get_encoding(void *ctx, binding_encoding_source *source)
{
libxml_ctx *c = (libxml_ctx *) ctx;
*source = c->encoding_source;
return c->encoding;
}
xmlDocPtr binding_get_document(void *ctx)
{
libxml_ctx *c = (libxml_ctx *) ctx;
xmlDocPtr doc = c->parser->myDoc;
c->parser->myDoc = NULL;
return doc;
}
/******************************************************************************/
/**
* Set the HTML parser character encoding.
*
* \param c context
* \param encoding name of encoding
* \return true on success, false on error and error reported
*/
bool set_parser_encoding(libxml_ctx *c, const char *encoding)
{
xmlError *error;
c->encoding_handler = xmlFindCharEncodingHandler(encoding);
if (!c->encoding_handler) {
/* either out of memory, or no handler available */
/* assume no handler available, which is not a fatal error */
LOG(("no encoding handler for \"%s\"", encoding));
/* \todo warn user and ask them to install iconv? */
return true;
}
xmlCtxtResetLastError(c->parser);
if (xmlSwitchToEncoding(c->parser, c->encoding_handler)) {
error = xmlCtxtGetLastError(c->parser);
LOG(("xmlSwitchToEncoding(): %s",
error ? error->message : "failed"));
return false;
}
/* Dirty hack to get around libxml oddness:
* 1) When creating a push parser context, the input flow's encoding
* string is not set (whether an encoding is specified or not)
* 2) When switching encoding (as above), the input flow's encoding
* string is never changed
* 3) When handling a meta charset, the input flow's encoding string
* is checked to determine if an encoding has already been set.
* If it has been set, then the meta charset is ignored.
*
* The upshot of this is that, if we don't explicitly set the input
* flow's encoding string here, any meta charset in the document
* will override our setting, which is incorrect behaviour.
*
* Ideally, this would be fixed in libxml, but that requires rather
* more knowledge than I currently have of what libxml is doing.
*/
if (!c->parser->input->encoding)
c->parser->input->encoding =
xmlStrdup((const xmlChar *) encoding);
/* Ensure noone else attempts to reset the encoding */
c->getenc = false;
return true;
}
/**
* Attempt to detect the encoding of some HTML data.
*
* \param data Pointer to HTML source data
* \param size Pointer to length of data
* \return a constant string giving the encoding, or 0 if the encoding
* appears to be some 8-bit encoding
*
* If a BOM is encountered, *data and *size will be modified to skip over it
*/
const char *detect_encoding(const char **data, size_t *size)
{
const unsigned char *d = (const unsigned char *) *data;
/* this detection assumes that the first two characters are <= 0xff */
if (*size < 4)
return 0;
if (d[0] == 0x00 && d[1] == 0x00 &&
d[2] == 0xfe && d[3] == 0xff) { /* BOM 00 00 fe ff */
*data += 4;
*size -= 4;
return "UTF-32BE";
} else if (d[0] == 0xff && d[1] == 0xfe &&
d[2] == 0x00 && d[3] == 0x00) { /* BOM ff fe 00 00 */
*data += 4;
*size -= 4;
return "UTF-32LE";
}
else if (d[0] == 0x00 && d[1] != 0x00 &&
d[2] == 0x00 && d[3] != 0x00) /* 00 xx 00 xx */
return "UTF-16BE";
else if (d[0] != 0x00 && d[1] == 0x00 &&
d[2] != 0x00 && d[3] == 0x00) /* xx 00 xx 00 */
return "UTF-16LE";
else if (d[0] == 0x00 && d[1] == 0x00 &&
d[2] == 0x00 && d[3] != 0x00) /* 00 00 00 xx */
return "ISO-10646-UCS-4";
else if (d[0] != 0x00 && d[1] == 0x00 &&
d[2] == 0x00 && d[3] == 0x00) /* xx 00 00 00 */
return "ISO-10646-UCS-4";
else if (d[0] == 0xfe && d[1] == 0xff) { /* BOM fe ff */
*data += 2;
*size -= 2;
return "UTF-16BE";
} else if (d[0] == 0xff && d[1] == 0xfe) { /* BOM ff fe */
*data += 2;
*size -= 2;
return "UTF-16LE";
} else if (d[0] == 0xef && d[1] == 0xbb &&
d[2] == 0xbf) { /* BOM ef bb bf */
*data += 3;
*size -= 3;
return "UTF-8";
}
return 0;
}
#endif