Style: Fix ignoring of STYLE elements with non-screen media.

We were handling the STYLE tag getting added in the
dom_default_action_DOMSubtreeModified_cb callback, however,
the media attribute dadn't been added by that point.

We now check it in the dom_default_action_DOMNodeInserted_cb
callback, at which time the media attribute is available for
checking.

Note, we should probably store the media type in the
html_stylesheet structure, but for now we just have an
`unused` boolean.

Also, it may be possible to optimise to avoid parsing non-
screen media STYLE element data if we could detect the media
earlier.

1 files changed, 38 insertions, 0 deletions

diff --git a/render/html_css.c b/render/html_css.c
index ba887167e..4d5469361 100644
--- a/render/html_css.c
+++ b/render/html_css.c
@@ -239,6 +239,7 @@ html_create_style_element(html_content *c, dom_node *style)
 	c->stylesheets[c->stylesheet_count].node = dom_node_ref(style);
 	c->stylesheets[c->stylesheet_count].sheet = NULL;
 	c->stylesheets[c->stylesheet_count].modified = false;
+	c->stylesheets[c->stylesheet_count].unused = false;
 	c->stylesheet_count++;
 
 	return c->stylesheets + (c->stylesheet_count - 1);
@@ -323,6 +324,37 @@ bool html_css_update_style(html_content *c, dom_node *style)
 	return true;
 }
 
+bool html_css_process_style(html_content *c, dom_node *node)
+{
+	unsigned int i;
+	dom_string *val;
+	dom_exception exc;
+	struct html_stylesheet *s;
+
+	/* Find sheet */
+	for (i = 0, s = c->stylesheets;	i != c->stylesheet_count; i++, s++) {
+		if (s->node == node)
+			break;
+	}
+
+		/* Should already exist */
+	if (i == c->stylesheet_count) {
+		return false;
+	}
+
+	exc = dom_element_get_attribute(node, 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) {
+			s->unused = true;
+		}
+		dom_string_unref(val);
+	}
+
+	return true;
+}
+
 bool html_css_process_link(html_content *htmlc, dom_node *node)
 {
 	dom_string *rel, *type_attr, *media, *href;
@@ -400,6 +432,7 @@ bool html_css_process_link(html_content *htmlc, dom_node *node)
 	htmlc->stylesheets = stylesheets;
 	htmlc->stylesheets[htmlc->stylesheet_count].node = NULL;
 	htmlc->stylesheets[htmlc->stylesheet_count].modified = false;
+	htmlc->stylesheets[htmlc->stylesheet_count].unused = false;
 
 	/* start fetch */
 	child.charset = htmlc->encoding;
@@ -584,6 +617,11 @@ html_css_new_selection_context(html_content *c, css_select_ctx **ret_select_ctx)
 		css_stylesheet *sheet = NULL;
 		css_origin origin = CSS_ORIGIN_AUTHOR;
 
+		/* Filter out stylesheets for non-screen media. */
+		if (hsheet->unused) {
+			continue;
+		}
+
 		if (i < STYLESHEET_USER) {
 			origin = CSS_ORIGIN_UA;
 		} else if (i < STYLESHEET_START) {