elinks/src/document/css/css.c

/** CSS module management
 * @file */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>

#include "elinks.h"

#include "cache/cache.h"
#include "config/home.h"
#include "config/options.h"
#include "document/css/css.h"
#include "document/css/parser.h"
#include "document/css/stylesheet.h"
#include "encoding/encoding.h"
#include "intl/gettext/libintl.h"
#include "main/module.h"
#include "network/connection.h"
#include "protocol/uri.h"
#include "session/session.h"
#include "util/error.h"
#include "util/memory.h"
#include "viewer/text/draw.h"


struct option_info css_options_info[] = {
	INIT_OPT_TREE("document", N_("Cascading Style Sheets"),
		"css", OPT_SORT,
		N_("Options concerning how to use CSS for styling documents.")),

	INIT_OPT_BOOL("document.css", N_("Enable CSS"),
		"enable", 0, 1,
		N_("Enable adding of CSS style info to documents.")),

	INIT_OPT_BOOL("document.css", N_("Ignore \"display: none\""),
		"ignore_display_none", 0, 1,
		N_("When enabled, elements are rendered, even when their display\n"
		"property has the value \"none\". Because ELinks's CSS support is\n"
		"still very incomplete, this setting can improve the way that some\n"
		"documents are rendered.")),

	INIT_OPT_BOOL("document.css", N_("Import external style sheets"),
		"import", 0, 1,
		N_("When enabled any external style sheets that are imported from\n"
		"either CSS itself using the @import keyword or from the HTML using\n"
		"<link> tags in the document header will also be downloaded.")),

	INIT_OPT_STRING("document.css", N_("Default style sheet"),
		"stylesheet", 0, "",
		N_("The path to the file containing the default user defined\n"
		"Cascading Style Sheet. It can be used to control the basic\n"
		"layout of HTML documents. The path is assumed to be relative\n"
		"to ELinks' home directory.\n"
		"Leave as \"\" to use built-in document styling.")),

	INIT_OPT_STRING("document.css", N_("Media types"),
		"media", 0, "tty",
		N_("CSS media types that ELinks claims to support, separated with\n"
		"commas.  The \"all\" type is implied.  Currently, only ASCII\n"
		"characters work reliably here.  See CSS2 section 7:\n"
		"http://www.w3.org/TR/1998/REC-CSS2-19980512/media.html")),

	NULL_OPTION_INFO,
};


/** Check whether ELinks claims to support a specific CSS media type.
 *
 * @param optstr
 *   Null-terminated value of the document.css.media option.
 * @param token
 *   A name parsed from a CSS file or from an HTML media attribute.
 *   Need not be null-terminated.
 * @param token_length
 *   Length of @a token, in bytes.
 *
 * Both strings should be in the ASCII charset.
 *
 * @return nonzero if the media type is supported, 0 if not.  */
int
supports_css_media_type(const unsigned char *optstr,
			const unsigned char *token, size_t token_length)
{
	/* Split @optstr into comma-delimited strings, strip leading
	 * and trailing spaces from each, and compare them to the
	 * token.  */
	while (*optstr != '\0') {
		const unsigned char *beg, *end;

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

		beg = optstr;
		optstr += strcspn(optstr, ",");
		end = optstr;
		while (end > beg && end[-1] == ' ')
			--end;

		/* W3C REC-html401-19991224 section 6.13:
		 *   "3. A case-sensitive match is then made with
		 *    the set of media types defined above."
		 * W3C REC-html401-19991224 section 14.2.3:
		 *   "media = media-descriptors [CI]"
		 *   where CI stands for case-insensitive.
		 * This mismatch has been reported to the
		 * www-html-editor@w3.org mailing list on 2000-11-16.
		 *
		 * W3C REC-CSS2-19980512 section 7.3:
		 *  "Media type names are case-insensitive."  */
		if (!strlcasecmp(token, token_length, beg, end - beg))
			return 1;

		while (*optstr == ',')
			++optstr;
	}

	/* An explicit "all" is probably rarer than e.g. "tty".  */
	if (!strlcasecmp(token, token_length, "all", 3))
		return 1;

	return 0;
}

void
import_css(struct css_stylesheet *css, struct uri *uri)
{
	/* Do we have it in the cache? (TODO: CSS cache) */
	struct cache_entry *cached;
	struct fragment *fragment;

	if (!uri || css->import_level >= MAX_REDIRECTS)
		return;

	cached = get_redirected_cache_entry(uri);
	if (!cached) return;

	fragment = get_cache_fragment(cached);
	if (fragment) {
		unsigned char *end = fragment->data + fragment->length;

		css->import_level++;
		css_parse_stylesheet(css, uri, fragment->data, end);
		css->import_level--;
	}
}


static void
import_css_file(struct css_stylesheet *css, struct uri *base_uri,
		const unsigned char *url, int urllen)
{
	struct string string, filename;

	if (!*url
	    || css->import_level >= MAX_REDIRECTS
	    || !init_string(&filename))
		return;

	if (*url != '/' && elinks_home) {
		add_to_string(&filename, elinks_home);
	}

	add_bytes_to_string(&filename, url, urllen);

	if (is_in_state(read_encoded_file(&filename, &string), S_OK)) {
		unsigned char *end = string.source + string.length;

		css->import_level++;
		css_parse_stylesheet(css, base_uri, string.source, end);
		done_string(&string);
		css->import_level--;
	}

	done_string(&filename);
}

struct css_stylesheet default_stylesheet = INIT_CSS_STYLESHEET(default_stylesheet, import_css_file);

static void
import_default_css(void)
{
	unsigned char *url = get_opt_str("document.css.stylesheet", NULL);

	if (!css_selector_set_empty(&default_stylesheet.selectors))
		done_css_stylesheet(&default_stylesheet);

	if (!*url) return;

	import_css_file(&default_stylesheet, NULL, url, strlen(url));
}

static int
change_hook_css(struct session *ses, struct option *current, struct option *changed)
{
	int reload_css = 0;

	if (!strcmp(changed->name, "stylesheet")) {
		/** @todo TODO: We need to update all entries in
		 * format cache. --jonas */
		import_default_css();
	}

	if (!strcmp(changed->name, "media"))
		reload_css = 1;

	/* Instead of using the value of the @ses parameter, iterate
	 * through the @sessions list.  The parameter may be NULL and
	 * anyway we don't support session-specific options yet.  */
	foreach (ses, sessions) draw_formatted(ses, 1 + reload_css);

	return 0;
}

static void
init_css(struct module *module)
{
	static const struct change_hook_info css_change_hooks[] = {
		{ "document.css",		change_hook_css },
		{ NULL,				NULL },
	};

	register_change_hooks(css_change_hooks);
	import_default_css();
}

void
done_css(struct module *module)
{
	done_css_stylesheet(&default_stylesheet);
}


struct module css_module = struct_module(
	/* name: */		N_("Cascading Style Sheets"),
	/* options: */		css_options_info,
	/* hooks: */		NULL,
	/* submodules: */	NULL,
	/* data: */		NULL,
	/* init: */		init_css,
	/* done: */		done_css
);