From 7b78ef336122f28c2d2b4cce253683941a31b797 Mon Sep 17 00:00:00 2001
From: Michael Drake <tlsa@netsurf-browser.org>
Date: Sat, 24 Sep 2016 12:44:28 +0100
Subject: 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.
---
 render/html.c          |  3 +++
 render/html.h          |  1 +
 render/html_css.c      | 38 ++++++++++++++++++++++++++++++++++++++
 render/html_internal.h |  1 +
 4 files changed, 43 insertions(+)

diff --git a/render/html.c b/render/html.c
index 5a2aa4f98..3ddcdc3e1 100644
--- a/render/html.c
+++ b/render/html.c
@@ -670,6 +670,9 @@ dom_default_action_DOMNodeInserted_cb(struct dom_event *evt, void *pw)
 			case DOM_HTML_ELEMENT_TYPE_IMG:
 				html_process_img(htmlc, (dom_node *) node);
 				break;
+			case DOM_HTML_ELEMENT_TYPE_STYLE:
+				html_css_process_style(htmlc, (dom_node *) node);
+				break;
 			default:
 				break;
 			}
diff --git a/render/html.h b/render/html.h
index 1052cb26e..871eb331e 100644
--- a/render/html.h
+++ b/render/html.h
@@ -60,6 +60,7 @@ struct html_stylesheet {
 	struct dom_node *node; /**< dom node associated with sheet */
 	struct hlcache_handle *sheet;
 	bool modified;
+	bool unused;
 };
 
 /**
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) {
diff --git a/render/html_internal.h b/render/html_internal.h
index f0e98158f..fd65707ce 100644
--- a/render/html_internal.h
+++ b/render/html_internal.h
@@ -321,6 +321,7 @@ nserror html_css_quirks_stylesheets(html_content *c);
 nserror html_css_free_stylesheets(html_content *html);
 
 bool html_css_process_link(html_content *htmlc, dom_node *node);
+bool html_css_process_style(html_content *htmlc, dom_node *node);
 bool html_css_update_style(html_content *c, dom_node *style);
 
 nserror html_css_new_selection_context(html_content *c,
-- 
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