netsurf/render/html_css.c

/*
 * Copyright 2013 Vincent Sanders <vince@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/>.
 */

/** \file
 * Processing for html content css operations.
 */

#include <assert.h>
#include <ctype.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>

#include "content/hlcache.h"
#include "desktop/options.h"
#include "render/html_internal.h"
#include "utils/corestrings.h"
#include "utils/config.h"
#include "utils/log.h"

static nsurl *html_default_stylesheet_url;
static nsurl *html_adblock_stylesheet_url;
static nsurl *html_quirks_stylesheet_url;
static nsurl *html_user_stylesheet_url;

static nserror css_error_to_nserror(css_error error)
{
	switch (error) {
	case CSS_OK:
		return NSERROR_OK;

	case CSS_NOMEM:
		return NSERROR_NOMEM;

	case CSS_BADPARM:
		return NSERROR_BAD_PARAMETER;

	case CSS_INVALID:
		return NSERROR_INVALID;

	case CSS_FILENOTFOUND:
		return NSERROR_NOT_FOUND;

	case CSS_NEEDDATA:
		return NSERROR_NEED_DATA;

	case CSS_BADCHARSET:
		return NSERROR_BAD_ENCODING;

	case CSS_EOF:
	case CSS_IMPORTS_PENDING:
	case CSS_PROPERTY_NOT_SET:
	default:
		break;
	}
	return NSERROR_CSS;
}

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

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

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

	assert(i != parent->stylesheet_count);

	switch (event->type) {
	case CONTENT_MSG_LOADING:
		break;

	case CONTENT_MSG_READY:
		break;

	case CONTENT_MSG_DONE:
		LOG(("done stylesheet slot %d '%s'", i,
				nsurl_access(hlcache_handle_get_url(css))));
		parent->base.active--;
		LOG(("%d fetches active", parent->base.active));
		break;

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

	case CONTENT_MSG_STATUS:
		if (event->data.explicit_status_text == NULL) {
			/* Object content's status text updated */
			html_set_status(parent,
					content_get_status_message(css));
			content_broadcast(&parent->base, CONTENT_MSG_STATUS,
					event->data);
		} else {
			/* Object content wants to set explicit message */
			content_broadcast(&parent->base, CONTENT_MSG_STATUS,
					event->data);
		}
		break;

	case CONTENT_MSG_POINTER:
		/* Really don't want this to continue after the switch */
		return NSERROR_OK;

	default:
		assert(0);
	}

	if (parent->base.active == 0) {
		html_begin_conversion(parent);
	}

	return NSERROR_OK;
}

/* exported interface documented in render/html.h */
struct html_stylesheet *html_get_stylesheets(hlcache_handle *h, unsigned int *n)
{
	html_content *c = (html_content *) hlcache_handle_get_content(h);

	assert(c != NULL);
	assert(n != NULL);

	*n = c->stylesheet_count;

	return c->stylesheets;
}


/* exported interface documented in render/html_internal.h */
nserror html_css_free_stylesheets(html_content *html)
{
	unsigned int i;

	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.data != NULL)) {
			nscss_destroy_css_data(html->stylesheets[i].data.internal.data);
			free(html->stylesheets[i].data.internal.data);
		}
	}
	free(html->stylesheets);

	return NSERROR_OK;
}

/* exported interface documented in render/html_internal.h */
nserror html_css_quirks_stylesheets(html_content *c)
{
	nserror ns_error = NSERROR_OK;
	hlcache_child_context child;

	assert(c->stylesheets != NULL);

	if (c->quirks == DOM_DOCUMENT_QUIRKS_MODE_FULL) {
		child.charset = c->encoding;
		child.quirks = c->base.quirks;

		ns_error = hlcache_handle_retrieve(html_quirks_stylesheet_url,
				0, content_get_url(&c->base), NULL,
				html_convert_css_callback, c, &child,
				CONTENT_CSS,
				&c->stylesheets[STYLESHEET_QUIRKS].data.external);
		if (ns_error != NSERROR_OK) {
			return ns_error;
		}

		c->base.active++;
		LOG(("%d fetches active", c->base.active));
	}

	return ns_error;
}

/* exported interface documented in render/html_internal.h */
nserror html_css_new_stylesheets(html_content *c)
{
	nserror ns_error;
	hlcache_child_context child;

	if (c->stylesheets != NULL) {
		return NSERROR_OK; /* already initialised */
	}

	/* stylesheet 0 is the base style sheet,
	 * stylesheet 1 is the quirks mode style sheet,
	 * stylesheet 2 is the adblocking stylesheet,
	 * stylesheet 3 is the user stylesheet */
	c->stylesheets = calloc(STYLESHEET_START, sizeof(struct html_stylesheet));
	if (c->stylesheets == NULL) {
		return NSERROR_NOMEM;
	}

	c->stylesheets[STYLESHEET_BASE].type = HTML_STYLESHEET_EXTERNAL;
	c->stylesheets[STYLESHEET_BASE].data.external = NULL;
	c->stylesheets[STYLESHEET_QUIRKS].type = HTML_STYLESHEET_EXTERNAL;
	c->stylesheets[STYLESHEET_QUIRKS].data.external = NULL;
	c->stylesheets[STYLESHEET_ADBLOCK].type = HTML_STYLESHEET_EXTERNAL;
	c->stylesheets[STYLESHEET_ADBLOCK].data.external = NULL;
	c->stylesheets[STYLESHEET_USER].type = HTML_STYLESHEET_EXTERNAL;
	c->stylesheets[STYLESHEET_USER].data.external = NULL;
	c->stylesheet_count = STYLESHEET_START;

	child.charset = c->encoding;
	child.quirks = c->base.quirks;

	ns_error = hlcache_handle_retrieve(html_default_stylesheet_url, 0,
			content_get_url(&c->base), NULL,
			html_convert_css_callback, c, &child, CONTENT_CSS,
			&c->stylesheets[STYLESHEET_BASE].data.external);
	if (ns_error != NSERROR_OK) {
		return ns_error;
	}

	c->base.active++;
	LOG(("%d fetches active", c->base.active));


	if (nsoption_bool(block_ads)) {
		ns_error = hlcache_handle_retrieve(html_adblock_stylesheet_url,
				0, content_get_url(&c->base), NULL,
				html_convert_css_callback, c, &child, CONTENT_CSS,
				&c->stylesheets[STYLESHEET_ADBLOCK].
						data.external);
		if (ns_error != NSERROR_OK) {
			return ns_error;
		}

		c->base.active++;
		LOG(("%d fetches active", c->base.active));

	}

	ns_error = hlcache_handle_retrieve(html_user_stylesheet_url, 0,
			content_get_url(&c->base), NULL,
			html_convert_css_callback, c, &child, CONTENT_CSS,
			&c->stylesheets[STYLESHEET_USER].data.external);
	if (ns_error != NSERROR_OK) {
		return ns_error;
	}

	c->base.active++;
	LOG(("%d fetches active", c->base.active));

	return ns_error;
}

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

	LOG(("Inline style %p done", css));

	/* Search HTML content for sheet */
	for (i = 0; i < html->stylesheet_count; i++) {
		if (html->stylesheets[i].type == HTML_STYLESHEET_INTERNAL &&
				html->stylesheets[i].data.internal.data == css)
			break;
	}

	/* Not found: must have been replaced, so destroy it */
	if (i == html->stylesheet_count) {
		LOG(("Not found: destroying"));
		nscss_destroy_css_data(css);
		free(css);
	} else {
		html->stylesheets[i].data.internal.done = true;
	}

	html->base.active--;
	LOG(("%d fetches active", html->base.active));
	if (html->base.active == 0) {
		html_begin_conversion(html);
	}
}

static nserror
html_stylesheet_from_domnode(html_content *c,
			     struct html_stylesheet *s,
			     dom_node *node)
{
	dom_node *child, *next;
	dom_exception exc;
	struct content_css_data *sheet, *old_sheet;
	bool old_sheet_done;
	nserror error;
	css_error csserror;

	/* create stylesheet */
	sheet = calloc(1, sizeof(struct content_css_data));
	if (sheet == NULL) {
		return NSERROR_NOMEM;
	}

	error = nscss_create_css_data(sheet,
		nsurl_access(c->base_url), NULL, c->quirks,
		html_inline_style_done, c);
	if (error != NSERROR_OK) {
		free(sheet);
		return error;
	}

	exc = dom_node_get_first_child(node, &child);
	if (exc != DOM_NO_ERR) {
		nscss_destroy_css_data(sheet);
		free(sheet);
		return NSERROR_DOM;
	}

	while (child != NULL) {
		dom_string *data;

		exc = dom_node_get_text_content(child, &data);
		if (exc != DOM_NO_ERR) {
			dom_node_unref(child);
			nscss_destroy_css_data(sheet);
			free(sheet);
			return NSERROR_DOM;
		}

		if (nscss_process_css_data(sheet,
				dom_string_data(data),
				dom_string_byte_length(data)) == false) {
			dom_string_unref(data);
			dom_node_unref(child);
			nscss_destroy_css_data(sheet);
			free(sheet);
			return NSERROR_CSS;
		}

		dom_string_unref(data);

		exc = dom_node_get_next_sibling(child, &next);
		if (exc != DOM_NO_ERR) {
			dom_node_unref(child);
			nscss_destroy_css_data(sheet);
			free(sheet);
			return NSERROR_DOM;
		}

		dom_node_unref(child);
		child = next;
	}

	c->base.active++;
	LOG(("%d fetches active", c->base.active));

	LOG(("Updating sheet %p with %p", s->data.internal, sheet));

	/* Update index */
	old_sheet = s->data.internal.data;
	old_sheet_done = s->data.internal.done;
	s->data.internal.data = sheet;
	s->data.internal.done = false;

	/* Convert the content -- manually, as we want the result */
	csserror = nscss_convert_css_data(sheet);
	if (csserror != CSS_OK) {
		/* conversion failed */
		c->base.active--;
		LOG(("%d fetches active", c->base.active));
		nscss_destroy_css_data(sheet);
		free(sheet);
		s->data.internal.data = old_sheet;
		s->data.internal.done = old_sheet_done;
		return css_error_to_nserror(csserror);
	}

	/* Clean up old sheet if it was already complete */
	if (old_sheet != NULL && old_sheet_done) {
		LOG(("Destroying old sheet %p", old_sheet));
		nscss_destroy_css_data(old_sheet);
		free(old_sheet);
	}

	return NSERROR_OK;
}

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

static struct html_stylesheet *
html_create_style_element(html_content *c, dom_node *style)
{
	dom_string *val;
	dom_exception exc;
	struct html_stylesheet *stylesheets;

	/* type='text/css', or not present (invalid but common) */
	exc = dom_element_get_attribute(style, corestring_dom_type, &val);
	if (exc == DOM_NO_ERR && val != NULL) {
		if (!dom_string_caseless_lwc_isequal(val,
				corestring_lwc_text_css)) {
			dom_string_unref(val);
			return NULL;
		}
		dom_string_unref(val);
	}

	/* media contains 'screen' or 'all' or not present */
	exc = dom_element_get_attribute(style, corestring_dom_media, &val);
	if (exc == DOM_NO_ERR && val != NULL) {
		if (strcasestr(dom_string_data(val), "screen") == NULL &&
				strcasestr(dom_string_data(val),
						"all") == NULL) {
			dom_string_unref(val);
			return NULL;
		}
		dom_string_unref(val);
	}

	/* Extend array */
	stylesheets = realloc(c->stylesheets,
			      sizeof(struct html_stylesheet) * (c->stylesheet_count + 1));
	if (stylesheets == NULL) {

		content_broadcast_errorcode(&c->base, NSERROR_NOMEM);
		return false;

	}
	c->stylesheets = stylesheets;

	c->stylesheets[c->stylesheet_count].type = HTML_STYLESHEET_INTERNAL;
	c->stylesheets[c->stylesheet_count].node = style;
	c->stylesheets[c->stylesheet_count].data.internal.data = NULL;
	c->stylesheets[c->stylesheet_count].data.internal.done = false;
	c->stylesheet_count++;

	return c->stylesheets + (c->stylesheet_count - 1);
}

bool html_css_update_style(html_content *c, dom_node *style)
{
	nserror error;
	unsigned int i;
	struct html_stylesheet *s;

	/* Find sheet */
	for (i = 0, s = c->stylesheets;	i != c->stylesheet_count; i++, s++) {
		if ((s->type == HTML_STYLESHEET_INTERNAL) &&
		    (s->node == style))
			break;
	}
	if (i == c->stylesheet_count) {
		s = html_create_style_element(c, style);
	}
	if (s == NULL) {
		LOG(("Could not find or create inline stylesheet for %p",
		     style));
		return false;
	}

	LOG(("Found sheet %p slot %d for node %p", s, i, style));

	error = html_stylesheet_from_domnode(c, s, style);
	if (error != NSERROR_OK) {
		LOG(("Failed to update sheet"));
		content_broadcast_errorcode(&c->base, error);
		return false;
	}

	return true;
}

bool html_css_process_link(html_content *htmlc, dom_node *node)
{
	dom_string *rel, *type_attr, *media, *href;
	struct html_stylesheet *stylesheets;
	nsurl *joined;
	dom_exception exc;
	nserror ns_error;
	hlcache_child_context child;

	/* rel=<space separated list, including 'stylesheet'> */
	exc = dom_element_get_attribute(node, corestring_dom_rel, &rel);
	if (exc != DOM_NO_ERR || rel == NULL)
		return true;

	if (strcasestr(dom_string_data(rel), "stylesheet") == 0) {
		dom_string_unref(rel);
		return true;
	} else if (strcasestr(dom_string_data(rel), "alternate") != 0) {
		/* Ignore alternate stylesheets */
		dom_string_unref(rel);
		return true;
	}
	dom_string_unref(rel);

	/* type='text/css' or not present */
	exc = dom_element_get_attribute(node, corestring_dom_type, &type_attr);
	if (exc == DOM_NO_ERR && type_attr != NULL) {
		if (!dom_string_caseless_lwc_isequal(type_attr,
				corestring_lwc_text_css)) {
			dom_string_unref(type_attr);
			return true;
		}
		dom_string_unref(type_attr);
	}

	/* media contains 'screen' or 'all' or not present */
	exc = dom_element_get_attribute(node, corestring_dom_media, &media);
	if (exc == DOM_NO_ERR && media != NULL) {
		if (strcasestr(dom_string_data(media), "screen") == NULL &&
		    strcasestr(dom_string_data(media), "all") == NULL) {
			dom_string_unref(media);
			return true;
		}
		dom_string_unref(media);
	}

	/* href='...' */
	exc = dom_element_get_attribute(node, corestring_dom_href, &href);
	if (exc != DOM_NO_ERR || href == NULL)
		return true;

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

	ns_error = nsurl_join(htmlc->base_url, dom_string_data(href), &joined);
	if (ns_error != NSERROR_OK) {
		dom_string_unref(href);
		goto no_memory;
	}
	dom_string_unref(href);

	LOG(("linked stylesheet %i '%s'", htmlc->stylesheet_count, nsurl_access(joined)));

	/* extend stylesheets array to allow for new sheet */
	stylesheets = realloc(htmlc->stylesheets,
			      sizeof(struct html_stylesheet) * (htmlc->stylesheet_count + 1));
	if (stylesheets == NULL) {
		nsurl_unref(joined);
		ns_error = NSERROR_NOMEM;
		goto no_memory;
	}

	htmlc->stylesheets = stylesheets;
	htmlc->stylesheets[htmlc->stylesheet_count].type = HTML_STYLESHEET_EXTERNAL;

	/* start fetch */
	child.charset = htmlc->encoding;
	child.quirks = htmlc->base.quirks;

	ns_error = hlcache_handle_retrieve(joined,
					   0,
					   content_get_url(&htmlc->base),
					   NULL,
					   html_convert_css_callback,
					   htmlc,
					   &child,
					   CONTENT_CSS,
					   &htmlc->stylesheets[htmlc->stylesheet_count].data.external);

	nsurl_unref(joined);

	if (ns_error != NSERROR_OK)
		goto no_memory;

	htmlc->stylesheet_count++;

	htmlc->base.active++;
	LOG(("%d fetches active", htmlc->base.active));

	return true;

no_memory:
	content_broadcast_errorcode(&htmlc->base, ns_error);
	return false;
}

nserror
html_css_new_selection_context(html_content *c, css_select_ctx **ret_select_ctx)
{
	uint32_t i;
	css_error css_ret;
	css_select_ctx *select_ctx;

	/* check that the base stylesheet loaded; layout fails without it */
	if (c->stylesheets[STYLESHEET_BASE].data.external == NULL) {
		return NSERROR_CSS_BASE;
	}

	/* Create selection context */
	css_ret = css_select_ctx_create(ns_realloc, c, &select_ctx);
	if (css_ret != CSS_OK) {
		return css_error_to_nserror(css_ret);
	}

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

		if (i < STYLESHEET_USER) {
			origin = CSS_ORIGIN_UA;
		} else if (i < STYLESHEET_START) {
			origin = CSS_ORIGIN_USER;
		}

		if ((hsheet->type == HTML_STYLESHEET_EXTERNAL) &&
		    (hsheet->data.external != NULL)) {
			sheet = nscss_get_stylesheet(hsheet->data.external);
		} else if (hsheet->type == HTML_STYLESHEET_INTERNAL) {
			sheet = hsheet->data.internal.data->sheet;
		}

		if (sheet != NULL) {
			css_ret = css_select_ctx_append_sheet(select_ctx,
							      sheet,
							      origin,
							      CSS_MEDIA_SCREEN);
			if (css_ret != CSS_OK) {
				css_select_ctx_destroy(select_ctx);
				return css_error_to_nserror(css_ret);
			}
		}
	}

	/* return new selection context to caller */
	*ret_select_ctx = select_ctx;
	return NSERROR_OK;
}

nserror html_css_init(void)
{
	nserror error;

	error = nsurl_create("resource:default.css",
			&html_default_stylesheet_url);
	if (error != NSERROR_OK)
		return error;

	error = nsurl_create("resource:adblock.css",
			&html_adblock_stylesheet_url);
	if (error != NSERROR_OK)
		return error;

	error = nsurl_create("resource:quirks.css",
			&html_quirks_stylesheet_url);
	if (error != NSERROR_OK)
		return error;

	error = nsurl_create("resource:user.css",
			&html_user_stylesheet_url);

	return error;
}

void html_css_fini(void)
{
	if (html_user_stylesheet_url != NULL) {
		nsurl_unref(html_user_stylesheet_url);
		html_user_stylesheet_url = NULL;
	}

	if (html_quirks_stylesheet_url != NULL) {
		nsurl_unref(html_quirks_stylesheet_url);
		html_quirks_stylesheet_url = NULL;
	}

	if (html_adblock_stylesheet_url != NULL) {
		nsurl_unref(html_adblock_stylesheet_url);
		html_adblock_stylesheet_url = NULL;
	}

	if (html_default_stylesheet_url != NULL) {
		nsurl_unref(html_default_stylesheet_url);
		html_default_stylesheet_url = NULL;
	}
}