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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const { fetch } = require("resource://devtools/shared/DevToolsUtils.js");
+
+/**
+ * For imported stylesheets, `ownerNode` is null.
+ *
+ * To resolve the ownerNode for an imported stylesheet, loop on `parentStylesheet`
+ * until we reach the topmost stylesheet, which should have a valid ownerNode.
+ *
+ * Constructable stylesheets do not have an owner node and this method will
+ * return null.
+ *
+ * @param {StyleSheet}
+ * The stylesheet for which we want to retrieve the ownerNode.
+ * @return {DOMNode|null} The ownerNode or null for constructable stylesheets.
+ */
+function getStyleSheetOwnerNode(sheet) {
+ // If this is not an imported stylesheet and we have an ownerNode available
+ // bail out immediately.
+ if (sheet.ownerNode) {
+ return sheet.ownerNode;
+ }
+
+ let parentStyleSheet = sheet;
+ while (
+ parentStyleSheet.parentStyleSheet &&
+ parentStyleSheet !== parentStyleSheet.parentStyleSheet
+ ) {
+ parentStyleSheet = parentStyleSheet.parentStyleSheet;
+ }
+
+ return parentStyleSheet.ownerNode;
+}
+
+exports.getStyleSheetOwnerNode = getStyleSheetOwnerNode;
+
+/**
+ * Get the text of a stylesheet.
+ *
+ * TODO: A call site in window-global.js expects this method to return a promise
+ * so it is mandatory to keep it as an async function even if we are not using
+ * await explicitly. Bug 1810572.
+ *
+ * @param {StyleSheet}
+ * The stylesheet for which we want to retrieve the text.
+ * @returns {Promise}
+ */
+async function getStyleSheetText(styleSheet) {
+ if (!styleSheet.href) {
+ if (styleSheet.ownerNode) {
+ // this is an inline <style> sheet
+ return styleSheet.ownerNode.textContent;
+ }
+ // Constructed stylesheet.
+ // TODO(bug 1769933, bug 1809108): Maybe preserve authored text?
+ return "";
+ }
+
+ return fetchStyleSheetText(styleSheet);
+}
+
+exports.getStyleSheetText = getStyleSheetText;
+
+/**
+ * Retrieve the content of a given stylesheet
+ *
+ * @param {StyleSheet} styleSheet
+ * @returns {String}
+ */
+async function fetchStyleSheetText(styleSheet) {
+ const href = styleSheet.href;
+
+ const options = {
+ loadFromCache: true,
+ policy: Ci.nsIContentPolicy.TYPE_INTERNAL_STYLESHEET,
+ charset: getCSSCharset(styleSheet),
+ };
+
+ // Bug 1282660 - We use the system principal to load the default internal
+ // stylesheets instead of the content principal since such stylesheets
+ // require system principal to load. At meanwhile, we strip the loadGroup
+ // for preventing the assertion of the userContextId mismatching.
+
+ // chrome|file|resource|moz-extension protocols rely on the system principal.
+ const excludedProtocolsRe = /^(chrome|file|resource|moz-extension):\/\//;
+ if (!excludedProtocolsRe.test(href)) {
+ // Stylesheets using other protocols should use the content principal.
+ const ownerNode = getStyleSheetOwnerNode(styleSheet);
+ if (ownerNode) {
+ // eslint-disable-next-line mozilla/use-ownerGlobal
+ options.window = ownerNode.ownerDocument.defaultView;
+ options.principal = ownerNode.ownerDocument.nodePrincipal;
+ }
+ }
+
+ let result;
+
+ try {
+ result = await fetch(href, options);
+ } catch (e) {
+ // The list of excluded protocols can be missing some protocols, try to use the
+ // system principal if the first fetch failed.
+ console.error(
+ `stylesheets: fetch failed for ${href},` +
+ ` using system principal instead.`
+ );
+ options.window = undefined;
+ options.principal = undefined;
+ result = await fetch(href, options);
+ }
+
+ return result.content;
+}
+
+/**
+ * Get charset of a given stylesheet
+ *
+ * @param {StyleSheet} styleSheet
+ * @returns {String}
+ */
+function getCSSCharset(styleSheet) {
+ if (styleSheet) {
+ // charset attribute of <link> or <style> element, if it exists
+ if (styleSheet.ownerNode?.getAttribute) {
+ const linkCharset = styleSheet.ownerNode.getAttribute("charset");
+ if (linkCharset != null) {
+ return linkCharset;
+ }
+ }
+
+ // charset of referring document.
+ if (styleSheet.ownerNode?.ownerDocument.characterSet) {
+ return styleSheet.ownerNode.ownerDocument.characterSet;
+ }
+ }
+
+ return "UTF-8";
+}