netsurf/render/html.c

/*
 * Copyright 2007 James Bursa <bursa@users.sourceforge.net>
 *
 * 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/>.
 */

/** \file
 * Content for text/html (implementation).
 */

#define _GNU_SOURCE /* for strndup() */

#include <assert.h>
#include <ctype.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>
#include "utils/config.h"
#include "content/content_protected.h"
#include "content/fetch.h"
#include "content/hlcache.h"
#include "desktop/browser.h"
#include "desktop/gui.h"
#include "desktop/options.h"
#include "image/bitmap.h"
#include "render/box.h"
#include "render/favicon.h"
#include "render/font.h"
#include "render/form.h"
#include "render/html.h"
#include "render/imagemap.h"
#include "render/layout.h"
#include "utils/http.h"
#include "utils/log.h"
#include "utils/messages.h"
#include "utils/talloc.h"
#include "utils/url.h"
#include "utils/utils.h"

#define CHUNK 4096

/* Change these to 1 to cause a dump to stderr of the frameset or box
 * when the trees have been built.
 */
#define ALWAYS_DUMP_FRAMESET 0
#define ALWAYS_DUMP_BOX 0

static void html_finish_conversion(struct content *c);
static nserror html_convert_css_callback(hlcache_handle *css,
		const hlcache_event *event, void *pw);
static bool html_meta_refresh(struct content *c, xmlNode *head);
static bool html_head(struct content *c, xmlNode *head);
static bool html_find_stylesheets(struct content *c, xmlNode *html);
static bool html_process_style_element(struct content *c, unsigned int *index,
		xmlNode *style);
static void html_inline_style_done(struct content_css_data *css, void *pw);
static bool html_replace_object(struct content *c, unsigned int i, 
		const char *url);
static nserror html_object_callback(hlcache_handle *object,
		const hlcache_event *event, void *pw);
static void html_object_done(struct box *box, hlcache_handle *object,
			     bool background);
static void html_object_failed(struct box *box, struct content *content,
		bool background);
static bool html_object_type_permitted(const content_type type,
		const content_type *permitted_types);
static void html_object_refresh(void *p);
static void html_destroy_frameset(struct content_html_frames *frameset);
static void html_destroy_iframe(struct content_html_iframe *iframe);
#if ALWAYS_DUMP_FRAMESET
static void html_dump_frameset(struct content_html_frames *frame,
		unsigned int depth);
#endif

static const char empty_document[] =
	"<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\""
	"	\"http://www.w3.org/TR/html4/strict.dtd\">"
	"<html>"
	"<head>"
	"<title>Empty document</title>"
	"</head>"
	"<body>"
	"<h1>Empty document</h1>"
	"<p>The document sent by the server is empty.</p>"
	"</body>"
	"</html>";

/**
 * Allocator
 *
 * \param ptr   Pointer to reallocate, or NULL for new allocation
 * \param size  Number of bytes requires
 * \param pw    Allocation context
 * \return Pointer to allocated block, or NULL on failure
 */
static void *myrealloc(void *ptr, size_t len, void *pw)
{
	return realloc(ptr, len);
}

/**
 * Create a CONTENT_HTML.
 *
 * The content_html_data structure is initialized and the HTML parser is
 * created.
 */

bool html_create(struct content *c, const http_parameter *params)
{
	struct content_html_data *html = &c->data.html;
	const char *charset;
	union content_msg_data msg_data;
	binding_error error;
	nserror nerror;

	html->parser_binding = NULL;
	html->document = NULL;
	html->quirks = BINDING_QUIRKS_MODE_NONE;
	html->encoding = NULL;
	html->base_url = (char *) content__get_url(c);
	html->base_target = NULL;
	html->layout = NULL;
	html->background_colour = NS_TRANSPARENT;
	html->stylesheet_count = 0;
	html->stylesheets = NULL;
	html->select_ctx = NULL;
	html->object_count = 0;
	html->object = NULL;
	html->forms = NULL;
	html->imagemaps = NULL;
	html->bw = NULL;
	html->frameset = NULL;
	html->iframe = NULL;
	html->page = NULL;
	html->index = 0;
	html->box = NULL;
	html->font_func = &nsfont;

	nerror = http_parameter_list_find_item(params, "charset", &charset);
	if (nerror == NSERROR_OK) {
		html->encoding = talloc_strdup(c, charset);
		if (!html->encoding) {
			error = BINDING_NOMEM;
			goto error;
		}
		html->encoding_source = ENCODING_SOURCE_HEADER;
	}

	/* Create the parser binding */
	error = binding_create_tree(c, html->encoding, &html->parser_binding);
	if (error == BINDING_BADENCODING && html->encoding != NULL) {
		/* Ok, we don't support the declared encoding. Bailing out 
		 * isn't exactly user-friendly, so fall back to autodetect */
		talloc_free(html->encoding);
		html->encoding = NULL;

		error = binding_create_tree(c, html->encoding, 
				&html->parser_binding);
	}

	if (error != BINDING_OK)
		goto error;

	return true;

error:
	if (error == BINDING_BADENCODING) {
		LOG(("Bad encoding: %s", html->encoding ? html->encoding : ""));
		msg_data.error = messages_get("ParsingFail");
	} else
		msg_data.error = messages_get("NoMemory");

	content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
	return false;
}


/**
 * Process data for CONTENT_HTML.
 *
 * The data is parsed in chunks of size CHUNK, multitasking in between.
 */

bool html_process_data(struct content *c, const char *data, unsigned int size)
{
	unsigned long x;
	binding_error err;
	const char *encoding;

	for (x = 0; x + CHUNK <= size; x += CHUNK) {
		err = binding_parse_chunk(c->data.html.parser_binding,
				(const uint8_t *) data + x, CHUNK);
		if (err == BINDING_ENCODINGCHANGE) {
			goto encoding_change;
		} else if (err != BINDING_OK) {
			union content_msg_data msg_data;

			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);

			return false;
		}

		gui_multitask();
	}

	err = binding_parse_chunk(c->data.html.parser_binding,
			(const uint8_t *) data + x, (size - x));
	if (err == BINDING_ENCODINGCHANGE) {
		goto encoding_change;
	} else if (err != BINDING_OK) {
		union content_msg_data msg_data;

		msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);

		return false;
	}

	return true;

encoding_change:

	/* Retrieve new encoding */
	encoding = binding_get_encoding(
			c->data.html.parser_binding,
			&c->data.html.encoding_source);

	if (c->data.html.encoding != NULL)
		talloc_free(c->data.html.encoding);

	c->data.html.encoding = talloc_strdup(c, encoding);
	if (c->data.html.encoding == NULL) {
		union content_msg_data msg_data;

		msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
	}

	/* Destroy binding */
	binding_destroy_tree(c->data.html.parser_binding);

	/* Create new binding, using the new encoding */
	err = binding_create_tree(c, c->data.html.encoding,
			&c->data.html.parser_binding);
	if (err == BINDING_BADENCODING) {
		/* Ok, we don't support the declared encoding. Bailing out 
		 * isn't exactly user-friendly, so fall back to Windows-1252 */
		talloc_free(c->data.html.encoding);
		c->data.html.encoding = talloc_strdup(c, "Windows-1252");
		if (c->data.html.encoding == NULL) {
			union content_msg_data msg_data;

			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		}

		err = binding_create_tree(c, c->data.html.encoding,
				&c->data.html.parser_binding);
	}

	if (err != BINDING_OK) {
		union content_msg_data msg_data;

		if (err == BINDING_BADENCODING) {
			LOG(("Bad encoding: %s", c->data.html.encoding 
					? c->data.html.encoding : ""));
			msg_data.error = messages_get("ParsingFail");
		} else
			msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
	}

	{
		const char *source_data;
		unsigned long source_size;

		source_data = content__get_source_data(c, &source_size);

		/* Recurse to reprocess all that data.  This is safe because
		 * the encoding is now specified at parser-start which means
		 * it cannot be changed again. */
		return html_process_data(c, source_data, source_size);
	}
}

/**
 * Convert a CONTENT_HTML for display.
 *
 * The following steps are carried out in order:
 *
 *  - parsing to an XML tree is completed
 *  - stylesheets are fetched
 *  - favicon is retrieved
 *  - the XML tree is converted to a box tree and object fetches are started
 *
 * On exit, the content status will be either CONTENT_STATUS_DONE if the
 * document is completely loaded or CONTENT_STATUS_READY if objects are still
 * being fetched.
 */

bool html_convert(struct content *c)
{
	binding_error err;
	xmlNode *html, *head;
	union content_msg_data msg_data;
	unsigned long size;
	struct form *f;

	/* finish parsing */
	content__get_source_data(c, &size);
	if (size == 0) {
		/* Destroy current binding */
		binding_destroy_tree(c->data.html.parser_binding);

		/* Also, any existing encoding information, 
		 * as it's not guaranteed to match the error page.
		 */
		talloc_free(c->data.html.encoding);
		c->data.html.encoding = NULL;

		/* Create new binding, using default charset */
		err = binding_create_tree(c, NULL, 
				&c->data.html.parser_binding);
		if (err != BINDING_OK) {
			union content_msg_data msg_data;

			if (err == BINDING_BADENCODING) {
				LOG(("Bad encoding: %s", c->data.html.encoding 
						? c->data.html.encoding : ""));
				msg_data.error = messages_get("ParsingFail");
			} else
				msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		}

		/* Process the error page */
		if (html_process_data(c, (char *) empty_document, 
				SLEN(empty_document)) == false)
			return false;
	}

	err = binding_parse_completed(c->data.html.parser_binding);
	if (err != BINDING_OK) {
		union content_msg_data msg_data;

		msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);

		return false;
	}

	c->data.html.document =
			binding_get_document(c->data.html.parser_binding,
					&c->data.html.quirks);
	/*xmlDebugDumpDocument(stderr, c->data.html.document);*/

	if (!c->data.html.document) {
		LOG(("Parsing failed"));
		msg_data.error = messages_get("ParsingFail");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
	}

	if (c->data.html.encoding == NULL) {
		const char *encoding = binding_get_encoding(
				c->data.html.parser_binding, 
				&c->data.html.encoding_source);

		c->data.html.encoding = talloc_strdup(c, encoding);
		if (c->data.html.encoding == NULL) {
			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		}
	}

	/* locate html and head elements */
	html = xmlDocGetRootElement(c->data.html.document);
	if (html == 0 || strcmp((const char *) html->name, "html") != 0) {
		LOG(("html element not found"));
		msg_data.error = messages_get("ParsingFail");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
	}
	for (head = html->children;
			head != 0 && head->type != XML_ELEMENT_NODE;
			head = head->next)
		;
	if (head && strcmp((const char *) head->name, "head") != 0) {
		head = 0;
		LOG(("head element not found"));
	}

	if (head) {
		if (!html_head(c, head)) {
			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		}

		/* handle meta refresh */
		if (!html_meta_refresh(c, head))
			return false;
	}

	/* Retrieve forms from parser */
	c->data.html.forms = binding_get_forms(c->data.html.parser_binding);
	for (f = c->data.html.forms; f != NULL; f = f->prev) {
		char *action;
		url_func_result res;

		/* Make all actions absolute */
		res = url_join(f->action, c->data.html.base_url, &action);
		if (res != URL_FUNC_OK) {
			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		}

		free(f->action);
		f->action = action;

		/* Ensure each form has a document encoding */
		if (f->document_charset == NULL) {
			f->document_charset = strdup(c->data.html.encoding);
			if (f->document_charset == NULL) {
				msg_data.error = messages_get("NoMemory");
				content_broadcast(c, CONTENT_MSG_ERROR, 
						msg_data);
				return false;
			}
		}
	}

	/* get stylesheets */
	if (!html_find_stylesheets(c, html))
		return false;

	return true;
}

/**
 * Complete conversion of an HTML document
 * 
 * \param c  Content to convert
 */
void html_finish_conversion(struct content *c)
{
	union content_msg_data msg_data;
	xmlNode *html;
	uint32_t i;
	css_error error;

	html = xmlDocGetRootElement(c->data.html.document);
	assert(html != NULL);

	/* check that the base stylesheet loaded; layout fails without it */
	if (c->data.html.stylesheets[STYLESHEET_BASE].data.external == NULL) {
		msg_data.error = "Base stylesheet failed to load";
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		c->status = CONTENT_STATUS_ERROR;
		return;
	}

	/* Create selection context */
	error = css_select_ctx_create(myrealloc, c, &c->data.html.select_ctx);
	if (error != CSS_OK) {
		msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		c->status = CONTENT_MSG_ERROR;
		return;
	}

	/* Add sheets to it */
	for (i = STYLESHEET_BASE; i != c->data.html.stylesheet_count; i++) {
		const struct html_stylesheet *hsheet = 
				&c->data.html.stylesheets[i];
		css_stylesheet *sheet;
		css_origin origin = CSS_ORIGIN_AUTHOR;

		if (i < STYLESHEET_START)
			origin = CSS_ORIGIN_UA;

		if (hsheet->type == HTML_STYLESHEET_EXTERNAL &&
				hsheet->data.external != NULL) {
			struct content *s = hlcache_handle_get_content(
					hsheet->data.external);

			sheet = s-> data.css.sheet;
		} else if (hsheet->type == HTML_STYLESHEET_INTERNAL) {
			sheet = hsheet->data.internal->sheet;
		} else {
			sheet = NULL;
		}

		if (sheet != NULL) {
			error = css_select_ctx_append_sheet(
					c->data.html.select_ctx, sheet,
					origin, CSS_MEDIA_SCREEN);
			if (error != CSS_OK) {
				msg_data.error = messages_get("NoMemory");
				content_broadcast(c, CONTENT_MSG_ERROR, 
						msg_data);
				c->status = CONTENT_STATUS_ERROR;
				return;
			}
		}
	}

	/* get icon */
	favicon_get_icon(c, html);	

	/* convert xml tree to box tree */
	LOG(("XML to box"));
	content_set_status(c, messages_get("Processing"));
	content_broadcast(c, CONTENT_MSG_STATUS, msg_data);
	if (!xml_to_box(html, c)) {
		msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		c->status = CONTENT_STATUS_ERROR;
		return;
	}
#if ALWAYS_DUMP_BOX
	box_dump(stderr, c->data.html.layout->children, 0);
#endif
#if ALWAYS_DUMP_FRAMESET
	if (c->data.html.frameset)
                html_dump_frameset(c->data.html.frameset, 0);
#endif

	/* extract image maps - can't do this sensibly in xml_to_box */
	if (!imagemap_extract(html, c)) {
		LOG(("imagemap extraction failed"));
		msg_data.error = messages_get("NoMemory");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		c->status = CONTENT_STATUS_ERROR;
		return;
	}
	/*imagemap_dump(c);*/

	/* Destroy the parser binding */
	binding_destroy_tree(c->data.html.parser_binding);
	c->data.html.parser_binding = NULL;

	content_set_ready(c);

	if (c->active == 0)
		content_set_done(c);

	html_set_status(c, "");
}


/**
 * Process elements in <head>.
 *
 * \param  c     content structure
 * \param  head  xml node of head element
 * \return  true on success, false on memory exhaustion
 *
 * The title and base href are extracted if present.
 */

bool html_head(struct content *c, xmlNode *head)
{
	xmlNode *node;
	xmlChar *s;

	for (node = head->children; node != 0; node = node->next) {
		if (node->type != XML_ELEMENT_NODE)
			continue;

		LOG(("Node: %s", node->name));
		if (c->title == NULL && strcmp((const char *) node->name,
				"title") == 0) {
			xmlChar *title = xmlNodeGetContent(node);
			char *title2;
			if (!title)
				return false;
			title2 = squash_whitespace((const char *) title);
			xmlFree(title);
			if (!title2)
				return false;
			if (content__set_title(c, title2) == false) {
				free(title2);
				return false;
			}

			free(title2);

		} else if (strcmp((const char *) node->name, "base") == 0) {
			char *href = (char *) xmlGetProp(node,
					(const xmlChar *) "href");
			if (href) {
				char *url;
				url_func_result res;
				res = url_normalize(href, &url);
				if (res == URL_FUNC_OK) {
					c->data.html.base_url =
							talloc_strdup(c, url);
					free(url);
				}
				xmlFree(href);
			}
			/* don't use the central values to ease freeing later on */
			if ((s = xmlGetProp(node, (const xmlChar *) "target"))) {
				if ((!strcasecmp((const char *) s, "_blank")) ||
						(!strcasecmp((const char *) s,
								"_top")) ||
						(!strcasecmp((const char *) s,
								"_parent")) ||
						(!strcasecmp((const char *) s,
								"_self")) ||
						('a' <= s[0] && s[0] <= 'z') ||
						('A' <= s[0] && s[0] <= 'Z')) {  /* [6.16] */
					c->data.html.base_target =
						talloc_strdup(c,
							(const char *) s);
					if (!c->data.html.base_target) {
						xmlFree(s);
						return false;
					}
				}
				xmlFree(s);
			}
		}
	}
	return true;
}


/**
 * Search for meta refresh
 *
 * http://wp.netscape.com/assist/net_sites/pushpull.html
 *
 * \param c content structure
 * \param head xml node of head element
 * \return true on success, false otherwise (error reported)
 */

bool html_meta_refresh(struct content *c, xmlNode *head)
{
	xmlNode *n;
	xmlChar *equiv, *content;
	union content_msg_data msg_data;
	char *url, *end, *refresh = NULL, quote = 0;
	url_func_result res;

	for (n = head == 0 ? 0 : head->children; n; n = n->next) {
		if (n->type != XML_ELEMENT_NODE)
			continue;

		/* Recurse into noscript elements */
		if (strcmp((const char *) n->name, "noscript") == 0) {
			if (!html_meta_refresh(c, n)) {
				/* Some error occurred */
				return false;
			} else if (c->refresh) {
				/* Meta refresh found - stop */
				return true;
			}
		}

		if (strcmp((const char *) n->name, "meta")) {
			continue;
		}

		equiv = xmlGetProp(n, (const xmlChar *) "http-equiv");
		if (!equiv)
			continue;

		if (strcasecmp((const char *) equiv, "refresh")) {
			xmlFree(equiv);
			continue;
		}

		xmlFree(equiv);

		content = xmlGetProp(n, (const xmlChar *) "content");
		if (!content)
			continue;

		end = (char *) content + strlen((const char *) content);

		/* content  := *LWS intpart fracpart? *LWS [';' *LWS *1url *LWS]
		 * intpart  := 1*DIGIT
		 * fracpart := 1*('.' | DIGIT)
		 * url      := "url" *LWS '=' *LWS (url-nq | url-sq | url-dq)
		 * url-nq   := *urlchar
		 * url-sq   := "'" *(urlchar | '"') "'"
		 * url-dq   := '"' *(urlchar | "'") '"'
		 * urlchar  := [#x9#x21#x23-#x26#x28-#x7E] | nonascii
		 * nonascii := [#x80-#xD7FF#xE000-#xFFFD#x10000-#x10FFFF]
		 */

		/* *LWS intpart */
		msg_data.delay = (int)strtol((char *) content, &url, 10);
		/* a very small delay and self-referencing URL can cause a loop
		 * that grinds machines to a halt. To prevent this we set a
		 * minimum refresh delay of 1s. */
		if (msg_data.delay < 1)
			msg_data.delay = 1;

		/* fracpart? (ignored, as delay is integer only) */
		while (url < end && (('0' <= *url && *url <= '9') || 
				*url == '.')) {
			url++;
		}

		/* *LWS */
		while (url < end && isspace(*url)) {
			url++;
		}

		/* ';' */
		if (url < end && *url == ';')
			url++;

		/* *LWS */
		while (url < end && isspace(*url)) {
			url++;
		}

		if (url == end) {
			/* Just delay specified, so refresh current page */
			xmlFree(content);

			c->refresh = talloc_strdup(c, content__get_url(c));
			if (!c->refresh) {
				msg_data.error = messages_get("NoMemory");
				content_broadcast(c,
					CONTENT_MSG_ERROR, msg_data);
				return false;
			}

			content_broadcast(c, CONTENT_MSG_REFRESH, msg_data);
			break;
		}

		/* "url" */
		if (url <= end - 3) {
			if (strncasecmp(url, "url", 3) == 0) {
				url += 3;
			} else {
				/* Unexpected input, ignore this header */
				continue;
			}
		} else {
			/* Insufficient input, ignore this header */
			continue;
		}

		/* *LWS */
		while (url < end && isspace(*url)) {
			url++;
		}

		/* '=' */
		if (url < end) {
			if (*url == '=') {
				url++;
			} else {
				/* Unexpected input, ignore this header */
				continue;
			}
		} else {
			/* Insufficient input, ignore this header */
			continue;
		}

		/* *LWS */
		while (url < end && isspace(*url)) {
			url++;
		}

		/* '"' or "'" */
		if (url < end && (*url == '"' || *url == '\'')) {
			quote = *url;
			url++;
		}

		/* Start of URL */
		refresh = url;

		if (quote != 0) {
			/* url-sq | url-dq */
			while (url < end && *url != quote)
				url++;
		} else {
			/* url-nq */
			while (url < end && !isspace(*url))
				url++;
		}

		/* '"' or "'" or *LWS (we don't care) */
		if (url < end)
			*url = '\0';

		res = url_join(refresh, c->data.html.base_url, &refresh);

		xmlFree(content);

		if (res == URL_FUNC_NOMEM) {
			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		} else if (res == URL_FUNC_FAILED) {
			/* This isn't fatal so carry on looking */
			continue;
		}

		c->refresh = talloc_strdup(c, refresh);

		free(refresh);

		if (!c->refresh) {
			msg_data.error = messages_get("NoMemory");
			content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
			return false;
		}

		content_broadcast(c, CONTENT_MSG_REFRESH, msg_data);
	}

	return true;
}


/**
 * Process inline stylesheets and fetch linked stylesheets.
 *
 * Uses STYLE and LINK elements inside and outside HEAD
 *
 * \param  c     content structure
 * \param  html  xml node of html element
 * \return  true on success, false if an error occurred
 */

bool html_find_stylesheets(struct content *c, xmlNode *html)
{
	static const content_type accept[] = { CONTENT_CSS, CONTENT_UNKNOWN };
	xmlNode *node;
	char *rel, *type, *media, *href, *url, *url2;
	unsigned int i = STYLESHEET_START;
	union content_msg_data msg_data;
	url_func_result res;
	struct html_stylesheet *stylesheets;
	hlcache_child_context child;
	nserror ns_error;

	child.charset = c->data.html.encoding;
	child.quirks = c->quirks;

	/* stylesheet 0 is the base style sheet,
	 * stylesheet 1 is the quirks mode style sheet,
	 * stylesheet 2 is the adblocking stylesheet */
	c->data.html.stylesheets = talloc_array(c, struct html_stylesheet,
			STYLESHEET_START);
	if (c->data.html.stylesheets == NULL)
		goto no_memory;
	c->data.html.stylesheets[STYLESHEET_BASE].type = 
			HTML_STYLESHEET_EXTERNAL;
	c->data.html.stylesheets[STYLESHEET_BASE].data.external = NULL;
	c->data.html.stylesheets[STYLESHEET_QUIRKS].type = 
			HTML_STYLESHEET_EXTERNAL;
	c->data.html.stylesheets[STYLESHEET_QUIRKS].data.external = NULL;
	c->data.html.stylesheets[STYLESHEET_ADBLOCK].type = 
			HTML_STYLESHEET_EXTERNAL;
	c->data.html.stylesheets[STYLESHEET_ADBLOCK].data.external = NULL;
	c->data.html.stylesheet_count = STYLESHEET_START;

	c->active = 0;

	ns_error = hlcache_handle_retrieve(default_stylesheet_url, 0,
			content__get_url(c), NULL,
			html_convert_css_callback, c, &child, accept,
			&c->data.html.stylesheets[
					STYLESHEET_BASE].data.external);
	if (ns_error != NSERROR_OK)
		goto no_memory;

	c->active++;

	if (c->data.html.quirks == BINDING_QUIRKS_MODE_FULL) {
		ns_error = hlcache_handle_retrieve(quirks_stylesheet_url, 0,
				content__get_url(c), NULL,
				html_convert_css_callback, c, &child, accept,
				&c->data.html.stylesheets[
					STYLESHEET_QUIRKS].data.external);
		if (ns_error != NSERROR_OK)
			goto no_memory;

		c->active++;
	}

	if (option_block_ads) {
		ns_error = hlcache_handle_retrieve(adblock_stylesheet_url, 0,
				content__get_url(c), NULL,
				html_convert_css_callback, c, &child, accept,
				&c->data.html.stylesheets[
					STYLESHEET_ADBLOCK].data.external);
		if (ns_error != NSERROR_OK)
			goto no_memory;

		c->active++;
	}

	node = html;

	/* depth-first search the tree for link elements */
	while (node) {
		if (node->children) {  /* 1. children */
			node = node->children;
		} else if (node->next) {  /* 2. siblings */
			node = node->next;
		} else {  /* 3. ancestor siblings */
			while (node && !node->next)
				node = node->parent;
			if (!node)
				break;
			node = node->next;
		}

		assert(node);

		if (node->type != XML_ELEMENT_NODE)
			continue;

		if (strcmp((const char *) node->name, "link") == 0) {
			/* rel=<space separated list, including 'stylesheet'> */
			if ((rel = (char *) xmlGetProp(node,
					(const xmlChar *) "rel")) == NULL)
				continue;
			if (strcasestr(rel, "stylesheet") == 0) {
				xmlFree(rel);
				continue;
			} else if (strcasestr(rel, "alternate")) {
				/* Ignore alternate stylesheets */
				xmlFree(rel);
				continue;
			}
			xmlFree(rel);

			/* type='text/css' or not present */
			if ((type = (char *) xmlGetProp(node,
					(const xmlChar *) "type")) != NULL) {
				if (strcmp(type, "text/css") != 0) {
					xmlFree(type);
					continue;
				}
				xmlFree(type);
			}

			/* media contains 'screen' or 'all' or not present */
			if ((media = (char *) xmlGetProp(node,
					(const xmlChar *) "media")) != NULL) {
				if (strcasestr(media, "screen") == NULL &&
						strcasestr(media, "all") == 
						NULL) {
					xmlFree(media);
					continue;
				}
				xmlFree(media);
			}

			/* href='...' */
			if ((href = (char *) xmlGetProp(node,
					(const xmlChar *) "href")) == NULL)
				continue;

			/* TODO: only the first preferred stylesheets (ie.
			 * those with a title attribute) should be loaded
			 * (see HTML4 14.3) */

			res = url_join(href, c->data.html.base_url, &url);
			xmlFree(href);
			if (res != URL_FUNC_OK)
				continue;

			LOG(("linked stylesheet %i '%s'", i, url));

			res = url_normalize(url, &url2);

			free(url);

			if (res != URL_FUNC_OK) {
				if (res == URL_FUNC_NOMEM)
					goto no_memory;
				continue;
			}

			/* start fetch */
			stylesheets = talloc_realloc(c,
					c->data.html.stylesheets,
					struct html_stylesheet, i + 1);
			if (stylesheets == NULL) {
				free(url2);
				goto no_memory;
			}

			c->data.html.stylesheets = stylesheets;
			c->data.html.stylesheet_count++;
			c->data.html.stylesheets[i].type =
					HTML_STYLESHEET_EXTERNAL;
			ns_error = hlcache_handle_retrieve(url2, 0,
					content__get_url(c), NULL,
					html_convert_css_callback, c, &child,
					accept,
					&c->data.html.stylesheets[i].
							data.external);

			free(url2);

			if (ns_error != NSERROR_OK)
				goto no_memory;

			c->active++;

			i++;
		} else if (strcmp((const char *) node->name, "style") == 0) {
			if (!html_process_style_element(c, &i, node))
				return false;
		}
	}

	assert(c->data.html.stylesheet_count == i);

	return true;

no_memory:
	msg_data.error = messages_get("NoMemory");
	content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
	return false;
}


/**
 * Process an inline stylesheet in the document.
 *
 * \param  c      content structure
 * \param  index  Index of stylesheet in stylesheet_content array, 
 *                updated if successful
 * \param  style  xml node of style element
 * \return  true on success, false if an error occurred
 */

bool html_process_style_element(struct content *c, unsigned int *index,
		xmlNode *style)
{
	xmlNode *child;
	char *type, *media, *data;
	union content_msg_data msg_data;
	struct html_stylesheet *stylesheets;
	struct content_css_data *sheet;
	nserror error;

	/* type='text/css', or not present (invalid but common) */
	if ((type = (char *) xmlGetProp(style, (const xmlChar *) "type"))) {
		if (strcmp(type, "text/css") != 0) {
			xmlFree(type);
			return true;
		}
		xmlFree(type);
	}

	/* media contains 'screen' or 'all' or not present */
	if ((media = (char *) xmlGetProp(style, (const xmlChar *) "media"))) {
		if (strcasestr(media, "screen") == NULL &&
				strcasestr(media, "all") == NULL) {
			xmlFree(media);
			return true;
		}
		xmlFree(media);
	}

	/* Extend array */
	stylesheets = talloc_realloc(c, c->data.html.stylesheets,
			struct html_stylesheet, *index + 1);
	if (stylesheets == NULL)
		goto no_memory;

	c->data.html.stylesheets = stylesheets;
	c->data.html.stylesheet_count++;

	c->data.html.stylesheets[(*index)].type = HTML_STYLESHEET_INTERNAL;
	c->data.html.stylesheets[(*index)].data.internal = NULL;

	/* create stylesheet */
	sheet = talloc(c, struct content_css_data);
	if (sheet == NULL) {
		c->data.html.stylesheet_count--;
		goto no_memory;
	}

	error = nscss_create_css_data(sheet,
		c->data.html.base_url, NULL, c->data.html.quirks);
	if (error != NSERROR_OK) {
		c->data.html.stylesheet_count--;
		goto no_memory;
	}

	/* can't just use xmlNodeGetContent(style), because that won't
	 * give the content of comments which may be used to 'hide'
	 * the content */
	for (child = style->children; child != 0; child = child->next) {
		data = (char *) xmlNodeGetContent(child);
		if (nscss_process_css_data(sheet, data, strlen(data)) == 
				false) {
			xmlFree(data);
			nscss_destroy_css_data(sheet);
			talloc_free(sheet);
			c->data.html.stylesheet_count--;
			/** \todo  not necessarily caused by
			 *  memory exhaustion */
			goto no_memory;
		}
		xmlFree(data);
	}

	c->active++;

	/* Convert the content -- manually, as we want the result */
	if (nscss_convert_css_data(sheet, 
			html_inline_style_done, c) != CSS_OK) {
		/* conversion failed */
		c->active--;
		nscss_destroy_css_data(sheet);
		talloc_free(sheet);
		sheet = NULL;
	}

	/* Update index */
	c->data.html.stylesheets[(*index)].data.internal = sheet;
	(*index)++;

	return true;

no_memory:
	msg_data.error = messages_get("NoMemory");
	content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
	return false;
}

/**
 * Handle notification of inline style completion
 *
 * \param css  Inline style object
 * \param pw   Private data
 */
void html_inline_style_done(struct content_css_data *css, void *pw)
{
	struct content *html = pw;

	if (--html->active == 0)
		html_finish_conversion(html);
}

/**
 * Callback for fetchcache() for linked stylesheets.
 */

nserror html_convert_css_callback(hlcache_handle *css,
		const hlcache_event *event, void *pw)
{
	struct content *parent = pw;
	unsigned int i;
	struct html_stylesheet *s;

	/* Find sheet */
	for (i = 0, s = parent->data.html.stylesheets; 
			i != parent->data.html.stylesheet_count; i++, s++) {
		if (s->type == HTML_STYLESHEET_EXTERNAL && 
				s->data.external == css)
			break;
	}

	assert(i != parent->data.html.stylesheet_count);

	switch (event->type) {
	case CONTENT_MSG_LOADING:
		/* check that the stylesheet is really CSS */
		if (content_get_type(css) != CONTENT_CSS) {
			assert(0 && "Non-CSS type unexpected");
		}
		break;

	case CONTENT_MSG_READY:
		break;

	case CONTENT_MSG_DONE:
		LOG(("got stylesheet '%s'", content_get_url(css)));
		parent->active--;
		break;

	case CONTENT_MSG_ERROR:
		LOG(("stylesheet %s failed: %s", 
				content_get_url(css), event->data.error));
		hlcache_handle_release(css);
		s->data.external = NULL;
		parent->active--;
		content_add_error(parent, "?", 0);
		break;

	case CONTENT_MSG_STATUS:
		html_set_status(parent, content_get_status_message(css));
		content_broadcast(parent, CONTENT_MSG_STATUS, event->data);
		break;

	default:
		assert(0);
	}

	if (parent->active == 0)
		html_finish_conversion(parent);

	return NSERROR_OK;
}


/**
 * Start a fetch for an object required by a page.
 *
 * \param  c                 content of type CONTENT_HTML
 * \param  url               URL of object to fetch (copied)
 * \param  box               box that will contain the object
 * \param  permitted_types   array of types, terminated by CONTENT_UNKNOWN,
 *	      or 0 if all types except OTHER and UNKNOWN acceptable
 * \param  available_width   estimate of width of object
 * \param  available_height  estimate of height of object
 * \param  background        this is a background image
 * \return  true on success, false on memory exhaustion
 */

bool html_fetch_object(struct content *c, const char *url, struct box *box,
		const content_type *permitted_types,
		int available_width, int available_height,
		bool background)
{
	unsigned int i = c->data.html.object_count;
	struct content_html_object *object;
	hlcache_handle *c_fetch;
	hlcache_child_context child;
	char *url2;
	url_func_result res;
	nserror error;

	child.charset = c->data.html.encoding;
	child.quirks = c->quirks;

	/* Normalize the URL */
	res = url_normalize(url, &url2);
	if (res != URL_FUNC_OK) {
		LOG(("failed to normalize url '%s'", url));
		return res != URL_FUNC_NOMEM;
	}

	error = hlcache_handle_retrieve(url2, 0, content__get_url(c), NULL,
			html_object_callback, c, &child, permitted_types,
			&c_fetch);

	/* No longer need normalized url */
	free(url2);

        if (error == NSERROR_OK) {
                /* add to object list */
                object = talloc_realloc(c, c->data.html.object,
                                        struct content_html_object, i + 1);
                if (object == NULL) {
                        hlcache_handle_release(c_fetch);
                        return false;
                }
                c->data.html.object = object;
                c->data.html.object[i].box = box;
                c->data.html.object[i].permitted_types = permitted_types;
                c->data.html.object[i].background = background;
                c->data.html.object[i].content = c_fetch;
                c->data.html.object_count++;
                c->active++;
        }
        
	return error != NSERROR_NOMEM;
}


/**
 * Start a fetch for an object required by a page, replacing an existing object.
 *
 * \param  c               content of type CONTENT_HTML
 * \param  i               index of object to replace in c->data.html.object
 * \param  url             URL of object to fetch (copied)
 * \return  true on success, false on memory exhaustion
 */

bool html_replace_object(struct content *c, unsigned int i, const char *url)
{
	hlcache_handle *c_fetch;
	hlcache_child_context child;
	struct content *page;
	char *url2;
	url_func_result res;
	nserror error;

	assert(c->type == CONTENT_HTML);

	child.charset = c->data.html.encoding;
	child.quirks = c->quirks;

	if (c->data.html.object[i].content) {
		/* remove existing object */
		if (content_get_status(c->data.html.object[i].content) !=
				CONTENT_STATUS_DONE)
			c->active--;
		hlcache_handle_release(c->data.html.object[i].content);
		c->data.html.object[i].content = NULL;
		c->data.html.object[i].box->object = NULL;
	}

	res = url_normalize(url, &url2);
	if (res != URL_FUNC_OK)
		return res != URL_FUNC_NOMEM;

	/* initialise fetch */
	error = hlcache_handle_retrieve(url2, 0, content__get_url(c), NULL,
			html_object_callback, c, &child,
			c->data.html.object[i].permitted_types,
			&c_fetch);

	free(url2);

	if (error != NSERROR_OK)
		return false;

	c->data.html.object[i].content = c_fetch;

	for (page = c; page; page = page->data.html.page) {
		assert(page->type == CONTENT_HTML);
		page->active++;
		page->status = CONTENT_STATUS_READY;
	}

	return true;
}


/**
 * Callback for fetchcache() for objects.
 */

nserror html_object_callback(hlcache_handle *object,
		const hlcache_event *event, void *pw)
{
	struct content *c = pw;
	unsigned int i;
	struct content_html_object *o;
	int x, y;
	struct box *box;

	/* Find object record in parent */
	for (i = 0, o = c->data.html.object; i != c->data.html.object_count;
			i++, o++) {
		if (o->content == object)
			break;
	}

	assert(i != c->data.html.object_count);

	box = o->box;

	switch (event->type) {
	case CONTENT_MSG_LOADING:
		/* check if the type is acceptable for this object */
		if (html_object_type_permitted(content_get_type(object),
				o->permitted_types)) {
			if (c->data.html.bw != NULL)
				content_open(object,
						c->data.html.bw, c,
						i, box,
						box->object_params);
			break;
		}

		/* not acceptable */
		hlcache_handle_release(object);

		o->content = NULL;

		c->active--;

		content_add_error(c, "?", 0);
		html_set_status(c, messages_get("BadObject"));
		content_broadcast(c, CONTENT_MSG_STATUS, event->data);

		html_object_failed(box, c,
				c->data.html.object[i].background);
		break;

	case CONTENT_MSG_READY:
		if (content_get_type(object) == CONTENT_HTML) {
			html_object_done(box, object, o->background);
			if (c->status == CONTENT_STATUS_READY ||
					c->status == CONTENT_STATUS_DONE)
				content__reformat(c,
						c->available_width,
						c->height);
		}
		break;

	case CONTENT_MSG_DONE:
		html_object_done(box, object, o->background);
		c->active--;
		break;

	case CONTENT_MSG_ERROR:
		hlcache_handle_release(object);

		o->content = NULL;

		c->active--;

		content_add_error(c, "?", 0);
		html_set_status(c, event->data.error);
		content_broadcast(c, CONTENT_MSG_STATUS, event->data);
		html_object_failed(box, c, o->background);
		break;

	case CONTENT_MSG_STATUS:
		html_set_status(c, content_get_status_message(object));
		/* content_broadcast(c, CONTENT_MSG_STATUS, 0); */
		break;

	case CONTENT_MSG_REFORMAT:
		break;

	case CONTENT_MSG_REDRAW:
	{
		union content_msg_data data = event->data;

		if (!box_visible(box))
			break;

		box_coords(box, &x, &y);

		if (hlcache_handle_get_content(object) == 
				event->data.redraw.object) {
			data.redraw.x = data.redraw.x *
					box->width / content_get_width(object);
			data.redraw.y = data.redraw.y *
					box->height / 
					content_get_height(object);
			data.redraw.width = data.redraw.width *
					box->width / content_get_width(object);
			data.redraw.height = data.redraw.height *
					box->height / 
					content_get_height(object);
			data.redraw.object_width = box->width;
			data.redraw.object_height = box->height;
		}

		data.redraw.x += x + box->padding[LEFT];
		data.redraw.y += y + box->padding[TOP];
		data.redraw.object_x += x + box->padding[LEFT];
		data.redraw.object_y += y + box->padding[TOP];

		content_broadcast(c, CONTENT_MSG_REDRAW, data);
	}
		break;

	case CONTENT_MSG_REFRESH:
		if (content_get_type(object) == CONTENT_HTML)
			/* only for HTML objects */
			schedule(event->data.delay * 100,
					html_object_refresh, object);
		break;

	default:
		assert(0);
	}

	if (c->status == CONTENT_STATUS_READY && c->active == 0 &&
			(event->type == CONTENT_MSG_LOADING ||
			event->type == CONTENT_MSG_DONE ||
			event->type == CONTENT_MSG_ERROR)) {
		/* all objects have arrived */
		content__reformat(c, c->available_width, c->height);
		html_set_status(c, "");
		content_set_done(c);
	}

	/* If  1) the configuration option to reflow pages while objects are
	 *        fetched is set
	 *     2) an object is newly fetched & converted,
	 *     3) the object's parent HTML is ready for reformat,
	 *     4) the time since the previous reformat is more than the
	 *        configured minimum time between reformats
	 * then reformat the page to display newly fetched objects */
	else if (option_incremental_reflow &&
			event->type == CONTENT_MSG_DONE &&
			(c->status == CONTENT_STATUS_READY ||
			 c->status == CONTENT_STATUS_DONE) &&
			(wallclock() > c->reformat_time)) {
		content__reformat(c, c->available_width, c->height);
	}

	return NSERROR_OK;
}


/**
 * Update a box whose content has completed rendering.
 */

void html_object_done(struct box *box, hlcache_handle *object,
		      bool background)
{
	struct box *b;

	if (background) {
		box->background = object;
		return;
	}

	box->object = object;

	/* invalidate parent min, max widths */
	for (b = box; b; b = b->parent)
		b->max_width = UNKNOWN_MAX_WIDTH;

	/* delete any clones of this box */
	while (box->next && box->next->clone) {
		/* box_free_box(box->next); */
		box->next = box->next->next;
	}
}


/**
 * Handle object fetching or loading failure.
 *
 * \param  box         box containing object which failed to load
 * \param  content     document of type CONTENT_HTML
 * \param  background  the object was the background image for the box
 *
 * Any fallback content for the object is made visible.
 */

void html_object_failed(struct box *box, struct content *content,
		bool background)
{
	struct box *b, *ic;

	if (background)
		return;
	if (!box->fallback)
		return;

	/* make fallback boxes into children or siblings, as appropriate */
	if (box->type != BOX_INLINE) {
		/* easy case: fallbacks become children */
		assert(box->type == BOX_BLOCK ||
				box->type == BOX_TABLE_CELL ||
				box->type == BOX_INLINE_BLOCK);
		box->children = box->fallback;
		box->last = box->children;
		while (box->last->next)
			box->last = box->last->next;
		box->fallback = 0;
		box_normalise_block(box, content);
	} else {
		assert(box->parent->type == BOX_INLINE_CONTAINER);
		if (box->fallback->type == BOX_INLINE_CONTAINER &&
				!box->fallback->next) {
			/* the fallback is a single inline container: splice
			 * it into this inline container */
			for (b = box->fallback->children; b; b = b->next)
				b->parent = box->parent;
			box->fallback->last->next = box->next;
			if (!box->next)
				box->parent->last = box->fallback->last;
			box->next = box->fallback->children;
			box->next->prev = box;
			box->fallback = 0;
		} else {
			if (box->next) {
				/* split this inline container into two inline
				 * containers */
				ic = box_create(0, 0, 0, 0, 0, content);
				if (!ic) {
					union content_msg_data msg_data;

					msg_data.error =
						messages_get("NoMemory");
					content_broadcast(content,
							CONTENT_MSG_ERROR,
							msg_data);
					return;
				}
				ic->type = BOX_INLINE_CONTAINER;
				box_insert_sibling(box->parent, ic);
				ic->children = box->next;
				ic->last = box->parent->last;
				ic->children->prev = 0;
				box->next = 0;
				box->parent->last = box;
				for (b = ic->children; b; b = b->next)
					b->parent = ic;
			}
			/* insert the fallback after the parent */
			for (b = box->fallback; b->next; b = b->next)
				b->parent = box->parent->parent;
			b->parent = box->parent->parent;
			/* [b is the last fallback box] */
			b->next = box->parent->next;
			if (b->next)
				b->next->prev = b;
			box->parent->next = box->fallback;
			box->fallback->prev = box->parent;
			box->fallback = 0;
			box_normalise_block(box->parent->parent, content);
		}
	}

	/* invalidate parent min, max widths */
	for (b = box->parent; b; b = b->parent)
		b->max_width = UNKNOWN_MAX_WIDTH;
	box->width = UNKNOWN_WIDTH;
}


/**
 * Check if a type is in a list.
 *
 * \param type the content_type to search for
 * \param permitted_types array of types, terminated by CONTENT_UNKNOWN,
 *	      or 0 if all types except OTHER and UNKNOWN acceptable
 * \return the type is in the list or acceptable
 */

bool html_object_type_permitted(const content_type type,
		const content_type *permitted_types)
{
	if (permitted_types) {
		for (; *permitted_types != CONTENT_UNKNOWN; permitted_types++)
			if (*permitted_types == type)
				return true;
	} else if (type < CONTENT_OTHER) {
		return true;
	}
	return false;
}


/**
 * schedule() callback for object refresh
 */

void html_object_refresh(void *p)
{
	struct content *c = (struct content *)p;

	assert(c->type == CONTENT_HTML);

	/* Ignore if refresh URL has gone
	 * (may happen if fetch errored) */
	if (!c->refresh)
		return;

	c->fresh = false;

	if (!html_replace_object(c->data.html.page, c->data.html.index,
			c->refresh)) {
		/** \todo handle memory exhaustion */
	}
}

/**
 * Stop loading a CONTENT_HTML in state READY.
 */

void html_stop(struct content *c)
{
	unsigned int i;
	hlcache_handle *object;

	assert(c->status == CONTENT_STATUS_READY);

	for (i = 0; i != c->data.html.object_count; i++) {
		object = c->data.html.object[i].content;
		if (object == NULL)
			continue;

		if (content_get_status(object) == CONTENT_STATUS_DONE)
			; /* already loaded: do nothing */
		else if (content_get_status(object) == CONTENT_STATUS_READY)
			hlcache_handle_abort(object);
		else {
			hlcache_handle_release(object);
			c->data.html.object[i].content = NULL;
		}
	}
	c->status = CONTENT_STATUS_DONE;
}


/**
 * Reformat a CONTENT_HTML to a new width.
 */

void html_reformat(struct content *c, int width, int height)
{
	struct box *layout;
	unsigned int time_before, time_taken;

	time_before = wallclock();

	layout_document(c, width, height);
	layout = c->data.html.layout;

	/* width and height are at least margin box of document */
	c->width = layout->x + layout->padding[LEFT] + layout->width +
			layout->padding[RIGHT] + layout->border[RIGHT].width +
			layout->margin[RIGHT];
	c->height = layout->y + layout->padding[TOP] + layout->height +
			layout->padding[BOTTOM] + layout->border[BOTTOM].width +
			layout->margin[BOTTOM];

	/* if boxes overflow right or bottom edge, expand to contain it */
	if (c->width < layout->x + layout->descendant_x1)
		c->width = layout->x + layout->descendant_x1;
	if (c->height < layout->y + layout->descendant_y1)
		c->height = layout->y + layout->descendant_y1;

	time_taken = wallclock() - time_before;
	c->reformat_time = wallclock() +
			((time_taken < option_min_reflow_period ?
			option_min_reflow_period : time_taken * 1.25));
}


/**
 * Destroy a CONTENT_HTML and free all resources it owns.
 */

void html_destroy(struct content *c)
{
	unsigned int i;
	struct form *f, *g;
	struct content_html_data *html;

	LOG(("content %p", c));

	html = &c->data.html;

	/* Destroy forms */
	for (f = html->forms; f != NULL; f = g) {
		g = f->prev;

		form_free(f);
	}

	if (html->favicon != NULL) {
		hlcache_handle_release(html->favicon);
		html->favicon = NULL;
	}

	imagemap_destroy(c);

	if (html->parser_binding != NULL)
		binding_destroy_tree(html->parser_binding);

	if (html->document != NULL)
		xmlFreeDoc(html->document);

	/* Free base target */
	if (html->base_target != NULL) {
	 	talloc_free(html->base_target);
	 	html->base_target = NULL;
	}

	/* Free frameset */
	if (html->frameset != NULL) {
		html_destroy_frameset(html->frameset);
		talloc_free(html->frameset);
		html->frameset = NULL;
	}

	/* Free iframes */
	if (html->iframe != NULL) {
		html_destroy_iframe(html->iframe);
		html->iframe = NULL;
	}

	/* Destroy selection context */
	if (html->select_ctx != NULL) {
		css_select_ctx_destroy(html->select_ctx);
		html->select_ctx = NULL;
	}

	/* Free stylesheets */
	for (i = 0; i != html->stylesheet_count; i++) {
		if (html->stylesheets[i].type == HTML_STYLESHEET_EXTERNAL &&
				html->stylesheets[i].data.external != NULL) {
			hlcache_handle_release(
					html->stylesheets[i].data.external);
		} else if (html->stylesheets[i].type == 
				HTML_STYLESHEET_INTERNAL &&
				html->stylesheets[i].data.internal != NULL) {
			nscss_destroy_css_data(
					html->stylesheets[i].data.internal);
		}
	}

	/* Free objects */
	for (i = 0; i != html->object_count; i++) {
		LOG(("object %i %p", i, html->object[i].content));
		if (html->object[i].content != NULL) {
			if (content_get_type(html->object[i].content) ==
					CONTENT_HTML)
				schedule_remove(html_object_refresh,
						html->object[i].content);

			hlcache_handle_release(html->object[i].content);
		}
	}
}

void html_destroy_frameset(struct content_html_frames *frameset) {
	int i;

	if (frameset->name) {
		talloc_free(frameset->name);
		frameset->name = NULL;
	}
	if (frameset->url) {
		talloc_free(frameset->url);
		frameset->url = NULL;
	}
	if (frameset->children) {
		for (i = 0; i < (frameset->rows * frameset->cols); i++) {
			if (frameset->children[i].name) {
				talloc_free(frameset->children[i].name);
				frameset->children[i].name = NULL;
			}
			if (frameset->children[i].url) {
				talloc_free(frameset->children[i].url);
				frameset->children[i].url = NULL;
			}
		  	if (frameset->children[i].children)
		  		html_destroy_frameset(&frameset->children[i]);
		}
		talloc_free(frameset->children);
		frameset->children = NULL;
	}
}

void html_destroy_iframe(struct content_html_iframe *iframe) {
	struct content_html_iframe *next;
	next = iframe;
	while ((iframe = next) != NULL) {
		next = iframe->next;
		if (iframe->name)
			talloc_free(iframe->name);
		if (iframe->url)
			talloc_free(iframe->url);
		talloc_free(iframe);
	}
}

bool html_clone(const struct content *old, struct content *new_content)
{
	/** \todo Clone HTML specifics */

	/* In the meantime, we should never be called, as HTML contents 
	 * cannot be shared and we're not intending to fix printing's 
	 * cloning of documents. */
	assert(0 && "html_clone should never be called");

	return true;
}

/**
 * Set the content status.
 */

void html_set_status(struct content *c, const char *extra)
{
	unsigned int stylesheets = 0, objects = 0;
	if (c->data.html.object_count == 0)
		stylesheets = c->data.html.stylesheet_count - c->active;
	else {
		stylesheets = c->data.html.stylesheet_count;
		objects = c->data.html.object_count - c->active;
	}
	content_set_status(c, "%u/%u %s %u/%u %s  %s",
			stylesheets, c->data.html.stylesheet_count,
			messages_get((c->data.html.stylesheet_count == 1) ?
					"styl" : "styls"),
			objects, c->data.html.object_count,
			messages_get((c->data.html.object_count == 1) ?
					"obj" : "objs"),
			extra);
}


/**
 * Handle a window containing a CONTENT_HTML being opened.
 */

void html_open(struct content *c, struct browser_window *bw,
		struct content *page, unsigned int index, struct box *box,
		struct object_params *params)
{
	unsigned int i;
	c->data.html.bw = bw;
	c->data.html.page = page;
	c->data.html.index = index;
	c->data.html.box = box;
	for (i = 0; i != c->data.html.object_count; i++) {
		if (c->data.html.object[i].content == 0)
			continue;
		if (content_get_type(c->data.html.object[i].content) == 
				CONTENT_UNKNOWN)
			continue;
               	content_open(c->data.html.object[i].content,
				bw, c, i,
				c->data.html.object[i].box,
				c->data.html.object[i].box->object_params);
	}
}


/**
 * Handle a window containing a CONTENT_HTML being closed.
 */

void html_close(struct content *c)
{
	unsigned int i;
	c->data.html.bw = 0;
	schedule_remove(html_object_refresh, c);
	for (i = 0; i != c->data.html.object_count; i++) {
		if (c->data.html.object[i].content == 0)
			continue;
		if (content_get_type(c->data.html.object[i].content) == 
				CONTENT_UNKNOWN)
			continue;
               	content_close(c->data.html.object[i].content);
	}
}

#if ALWAYS_DUMP_FRAMESET
/**
 * Print a frameset tree to stderr.
 */

void html_dump_frameset(struct content_html_frames *frame,
		unsigned int depth)
{
	unsigned int i;
	int row, col, index;
	const char *unit[] = {"px", "%", "*"};
	const char *scrolling[] = {"auto", "yes", "no"};

	assert(frame);

	fprintf(stderr, "%p ", frame);

	fprintf(stderr, "(%i %i) ", frame->rows, frame->cols);

	fprintf(stderr, "w%g%s ", frame->width.value, unit[frame->width.unit]);
	fprintf(stderr, "h%g%s ", frame->height.value,unit[frame->height.unit]);
	fprintf(stderr, "(margin w%i h%i) ",
			frame->margin_width, frame->margin_height);

	if (frame->name)
		fprintf(stderr, "'%s' ", frame->name);
	if (frame->url)
		fprintf(stderr, "<%s> ", frame->url);

	if (frame->no_resize)
		fprintf(stderr, "noresize ");
	fprintf(stderr, "(scrolling %s) ", scrolling[frame->scrolling]);
	if (frame->border)
		fprintf(stderr, "border %x ",
				(unsigned int) frame->border_colour);

	fprintf(stderr, "\n");

	if (frame->children) {
		for (row = 0; row != frame->rows; row++) {
			for (col = 0; col != frame->cols; col++) {
				for (i = 0; i != depth; i++)
					fprintf(stderr, "  ");
				fprintf(stderr, "(%i %i): ", row, col);
				index = (row * frame->cols) + col;
				html_dump_frameset(&frame->children[index],
						depth + 1);
			}
		}
	}
}

#endif

/**
 * Retrieve HTML document tree
 *
 * \param h  HTML content to retrieve document tree from
 * \return Pointer to document tree
 */
xmlDoc *html_get_document(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.document;
}

/**
 * Retrieve box tree
 *
 * \param h  HTML content to retrieve tree from
 * \return Pointer to box tree
 *
 * \todo This API must die, as must all use of the box tree outside render/
 */
struct box *html_get_box_tree(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.layout;
}

/**
 * Retrieve the charset of an HTML document
 *
 * \param h  Content to retrieve charset from
 * \return Pointer to charset, or NULL
 */
const char *html_get_encoding(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.encoding;
}

/**
 * Retrieve the charset of an HTML document
 *
 * \param h  Content to retrieve charset from
 * \return Pointer to charset, or NULL
 */
binding_encoding_source html_get_encoding_source(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.encoding_source;
}

/**
 * Retrieve framesets used in an HTML document
 *
 * \param h  Content to inspect
 * \return Pointer to framesets, or NULL if none
 */
struct content_html_frames *html_get_frameset(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.frameset;
}

/**
 * Retrieve iframes used in an HTML document
 *
 * \param h  Content to inspect
 * \return Pointer to iframes, or NULL if none
 */
struct content_html_iframe *html_get_iframe(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.iframe;
}

/**
 * Retrieve an HTML content's base URL
 *
 * \param h  Content to retrieve base target from
 * \return Pointer to URL
 */
const char *html_get_base_url(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.base_url;
}

/**
 * Retrieve an HTML content's base target
 *
 * \param h  Content to retrieve base target from
 * \return Pointer to target, or NULL if none
 */
const char *html_get_base_target(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.base_target;
}

/**
 * Retrieve stylesheets used by HTML document
 *
 * \param h  Content to retrieve stylesheets from
 * \param n  Pointer to location to receive number of sheets
 * \return Pointer to array of stylesheets
 */
struct html_stylesheet *html_get_stylesheets(hlcache_handle *h, unsigned int *n)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);
	assert(n != NULL);

	*n = c->data.html.stylesheet_count;

	return c->data.html.stylesheets;
}

/**
 * Retrieve objects used by HTML document
 *
 * \param h  Content to retrieve objects from
 * \param n  Pointer to location to receive number of objects
 * \return Pointer to array of objects
 */
struct content_html_object *html_get_objects(hlcache_handle *h, unsigned int *n)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);
	assert(n != NULL);

	*n = c->data.html.object_count;

	return c->data.html.object;
}

/**
 * Retrieve favicon associated with an HTML document
 *
 * \param h  HTML document to retrieve favicon from
 * \return Pointer to favicon, or NULL if none
 */
hlcache_handle *html_get_favicon(hlcache_handle *h)
{
	struct content *c = hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(c->type == CONTENT_HTML);

	return c->data.html.favicon;
}