11 files changed, 908 insertions, 0 deletions
diff --git a/toolkit/components/xulstore/XULStore.cpp b/toolkit/components/xulstore/XULStore.cpp
new file mode 100644
index 0000000000..a544746c6e
--- /dev/null
+++ b/toolkit/components/xulstore/XULStore.cpp
@@ -0,0 +1,108 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/XULStore.h"
+#include "nsCOMPtr.h"
+
+namespace mozilla {
+
+// The XULStore API is implemented in Rust and exposed to C++ via a set of
+// C functions with the "xulstore_" prefix.  We declare them in this anonymous
+// namespace to prevent C++ code outside this file from accessing them,
+// as they are an internal implementation detail, and C++ code should use
+// the mozilla::XULStore::* functions and mozilla::XULStoreIterator class
+// declared in XULStore.h.
+namespace {
+extern "C" {
+void xulstore_new_service(nsIXULStore** result);
+nsresult xulstore_set_value(const nsAString* doc, const nsAString* id,
+                            const nsAString* attr, const nsAString* value);
+nsresult xulstore_has_value(const nsAString* doc, const nsAString* id,
+                            const nsAString* attr, bool* has_value);
+nsresult xulstore_get_value(const nsAString* doc, const nsAString* id,
+                            const nsAString* attr, nsAString* value);
+nsresult xulstore_remove_value(const nsAString* doc, const nsAString* id,
+                               const nsAString* attr);
+XULStoreIterator* xulstore_get_ids(const nsAString* doc, nsresult* result);
+XULStoreIterator* xulstore_get_attrs(const nsAString* doc, const nsAString* id,
+                                     nsresult* result);
+bool xulstore_iter_has_more(const XULStoreIterator*);
+nsresult xulstore_iter_get_next(XULStoreIterator*, nsAString* value);
+void xulstore_iter_free(XULStoreIterator* iterator);
+nsresult xulstore_shutdown();
+}
+
+// A static reference to the nsIXULStore singleton that JS uses to access
+// the store.  Retrieved via mozilla::XULStore::GetService().
+static StaticRefPtr<nsIXULStore> sXULStore;
+}  // namespace
+
+bool XULStoreIterator::HasMore() const { return xulstore_iter_has_more(this); }
+
+nsresult XULStoreIterator::GetNext(nsAString* item) {
+  return xulstore_iter_get_next(this, item);
+}
+
+void DefaultDelete<XULStoreIterator>::operator()(XULStoreIterator* ptr) const {
+  xulstore_iter_free(ptr);
+}
+
+namespace XULStore {
+already_AddRefed<nsIXULStore> GetService() {
+  nsCOMPtr<nsIXULStore> xulStore;
+
+  if (sXULStore) {
+    xulStore = sXULStore;
+  } else {
+    xulstore_new_service(getter_AddRefs(xulStore));
+    sXULStore = xulStore;
+    mozilla::ClearOnShutdown(&sXULStore);
+  }
+
+  return xulStore.forget();
+}
+
+nsresult SetValue(const nsAString& doc, const nsAString& id,
+                  const nsAString& attr, const nsAString& value) {
+  return xulstore_set_value(&doc, &id, &attr, &value);
+}
+nsresult HasValue(const nsAString& doc, const nsAString& id,
+                  const nsAString& attr, bool& has_value) {
+  return xulstore_has_value(&doc, &id, &attr, &has_value);
+}
+nsresult GetValue(const nsAString& doc, const nsAString& id,
+                  const nsAString& attr, nsAString& value) {
+  return xulstore_get_value(&doc, &id, &attr, &value);
+}
+nsresult RemoveValue(const nsAString& doc, const nsAString& id,
+                     const nsAString& attr) {
+  return xulstore_remove_value(&doc, &id, &attr);
+}
+nsresult GetIDs(const nsAString& doc, UniquePtr<XULStoreIterator>& iter) {
+  // We assign the value of the iter here in C++ via a return value
+  // rather than in the Rust function via an out parameter in order
+  // to ensure that any old value is deleted, since the UniquePtr's
+  // assignment operator won't delete the old value if the assignment
+  // happens in Rust.
+  nsresult result;
+  iter.reset(xulstore_get_ids(&doc, &result));
+  return result;
+}
+nsresult GetAttrs(const nsAString& doc, const nsAString& id,
+                  UniquePtr<XULStoreIterator>& iter) {
+  // We assign the value of the iter here in C++ via a return value
+  // rather than in the Rust function via an out parameter in order
+  // to ensure that any old value is deleted, since the UniquePtr's
+  // assignment operator won't delete the old value if the assignment
+  // happens in Rust.
+  nsresult result;
+  iter.reset(xulstore_get_attrs(&doc, &id, &result));
+  return result;
+}
+nsresult Shutdown() { return xulstore_shutdown(); }
+
+};  // namespace XULStore
+};  // namespace mozilla
diff --git a/toolkit/components/xulstore/XULStore.h b/toolkit/components/xulstore/XULStore.h
new file mode 100644
index 0000000000..25b69ed12e
--- /dev/null
+++ b/toolkit/components/xulstore/XULStore.h
@@ -0,0 +1,56 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+/*
+ * This file declares the XULStore API for C++ via the mozilla::XULStore
+ * namespace and the mozilla::XULStoreIterator class.  It also declares
+ * the mozilla::XULStore::GetService() function that the component manager
+ * uses to instantiate and retrieve the nsIXULStore singleton.
+ */
+
+#ifndef mozilla_XULStore_h
+#define mozilla_XULStore_h
+
+#include "nsIXULStore.h"
+
+namespace mozilla {
+class XULStoreIterator final {
+ public:
+  bool HasMore() const;
+  nsresult GetNext(nsAString* item);
+
+ private:
+  XULStoreIterator() = delete;
+  XULStoreIterator(const XULStoreIterator&) = delete;
+  XULStoreIterator& operator=(const XULStoreIterator&) = delete;
+  ~XULStoreIterator() = delete;
+};
+
+template <>
+class DefaultDelete<XULStoreIterator> {
+ public:
+  void operator()(XULStoreIterator* ptr) const;
+};
+
+namespace XULStore {
+// Instantiates and retrieves the nsIXULStore singleton that JS uses to access
+// the store.  C++ code should use the mozilla::XULStore::* functions instead.
+already_AddRefed<nsIXULStore> GetService();
+
+nsresult SetValue(const nsAString& doc, const nsAString& id,
+                  const nsAString& attr, const nsAString& value);
+nsresult HasValue(const nsAString& doc, const nsAString& id,
+                  const nsAString& attr, bool& has_value);
+nsresult GetValue(const nsAString& doc, const nsAString& id,
+                  const nsAString& attr, nsAString& value);
+nsresult RemoveValue(const nsAString& doc, const nsAString& id,
+                     const nsAString& attr);
+nsresult GetIDs(const nsAString& doc, UniquePtr<XULStoreIterator>& iter);
+nsresult GetAttrs(const nsAString& doc, const nsAString& id,
+                  UniquePtr<XULStoreIterator>& iter);
+nsresult Shutdown();
+};  // namespace XULStore
+};  // namespace mozilla
+
+#endif  // mozilla_XULStore_h
diff --git a/toolkit/components/xulstore/XULStore.sys.mjs b/toolkit/components/xulstore/XULStore.sys.mjs
new file mode 100644
index 0000000000..eb1965ec6d
--- /dev/null
+++ b/toolkit/components/xulstore/XULStore.sys.mjs
@@ -0,0 +1,353 @@
+/* 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/. */
+
+// Enables logging and shorter save intervals.
+const debugMode = false;
+
+// Delay when a change is made to when the file is saved.
+// 30 seconds normally, or 3 seconds for testing
+const WRITE_DELAY_MS = (debugMode ? 3 : 30) * 1000;
+
+const XULSTORE_CID = Components.ID("{6f46b6f4-c8b1-4bd4-a4fa-9ebbed0753ea}");
+const STOREDB_FILENAME = "xulstore.json";
+
+/**
+ * The XULStore retains XULElement attributes such as the sizing and styling. These are
+ * stored in the user's profile directory inside of "xulstore.json". The JSON is
+ * stored based on the chrome URL of the resource.
+ *
+ * For instance the "chrome://browser/content/browser.xhtml" main window sizing could be
+ * stored like so:
+ *
+ * {
+ *   "chrome://browser/content/browser.xhtml": {
+ *     "main-window": {
+ *       "screenX": "1104",
+ *       "screenY": "25",
+ *       "width": "1904",
+ *       "height": "1612",
+ *       "sizemode": "normal"
+ *     },
+ *     ...
+ *   }
+ * }
+ *
+ * The XULStore can only be loaded in the parent process. See the XULStore
+ * and XULPersist C++ classes for how this is integrated from the C++ side.
+ */
+export function XULStore() {
+  if (!Services.appinfo.inSafeMode) {
+    this.load();
+  }
+}
+
+XULStore.prototype = {
+  classID: XULSTORE_CID,
+  name: "XULStore",
+  QueryInterface: ChromeUtils.generateQI([
+    "nsINamed",
+    "nsIObserver",
+    "nsIXULStore",
+    "nsISupportsWeakReference",
+  ]),
+
+  /* ---------- private members ---------- */
+
+  /*
+   * The format of _data is _data[docuri][elementid][attribute]. For example:
+   *  {
+   *      "chrome://blah/foo.xul" : {
+   *                                    "main-window" : { aaa : 1, bbb : "c" },
+   *                                    "barColumn"   : { ddd : 9, eee : "f" },
+   *                                },
+   *
+   *      "chrome://foopy/b.xul" :  { ... },
+   *      ...
+   *  }
+   */
+  _data: {},
+  _storeFile: null,
+  _needsSaving: false,
+  _saveAllowed: true,
+  _writeTimer: Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer),
+
+  load() {
+    Services.obs.addObserver(this, "profile-before-change", true);
+
+    try {
+      this._storeFile = Services.dirsvc.get("ProfD", Ci.nsIFile);
+    } catch (ex) {
+      try {
+        this._storeFile = Services.dirsvc.get("ProfDS", Ci.nsIFile);
+      } catch (ex) {
+        throw new Error("Can't find profile directory.");
+      }
+    }
+    this._storeFile.append(STOREDB_FILENAME);
+
+    this.readFile();
+  },
+
+  observe(subject, topic, data) {
+    this.writeFile();
+    if (topic == "profile-before-change") {
+      this._saveAllowed = false;
+    }
+  },
+
+  /*
+   * Internal function for logging debug messages to the Error Console window
+   */
+  log(message) {
+    if (!debugMode) {
+      return;
+    }
+    console.log("XULStore: " + message);
+  },
+
+  readFile() {
+    try {
+      this._data = JSON.parse(Cu.readUTF8File(this._storeFile));
+    } catch (e) {
+      this.log("Error reading JSON: " + e);
+      // This exception could mean that the file didn't exist.
+      // We'll just ignore the error and start with a blank slate.
+    }
+  },
+
+  async writeFile() {
+    if (!this._needsSaving) {
+      return;
+    }
+
+    this._needsSaving = false;
+
+    this.log("Writing to xulstore.json");
+
+    try {
+      await IOUtils.writeJSON(this._storeFile.path, this._data, {
+        tmpPath: this._storeFile.path + ".tmp",
+      });
+    } catch (e) {
+      this.log("Failed to write xulstore.json: " + e);
+      throw e;
+    }
+  },
+
+  markAsChanged() {
+    if (this._needsSaving || !this._storeFile) {
+      return;
+    }
+
+    // Don't write the file more than once every 30 seconds.
+    this._needsSaving = true;
+    this._writeTimer.init(this, WRITE_DELAY_MS, Ci.nsITimer.TYPE_ONE_SHOT);
+  },
+
+  /* ---------- interface implementation ---------- */
+
+  persist(node, attr) {
+    if (!node.id) {
+      throw new Error("Node without ID passed into persist()");
+    }
+
+    const uri = node.ownerDocument.documentURI;
+    const value = node.getAttribute(attr);
+
+    if (node.localName == "window") {
+      this.log("Persisting attributes to windows is handled by AppWindow.");
+      return;
+    }
+
+    // See Bug 1476680 - we could drop the `hasValue` check so that
+    // any time there's an empty attribute it gets removed from the
+    // store. Since this is copying behavior from document.persist,
+    // callers would need to be updated with that change.
+    if (!value && this.hasValue(uri, node.id, attr)) {
+      this.removeValue(uri, node.id, attr);
+    } else {
+      this.setValue(uri, node.id, attr, value);
+    }
+  },
+
+  setValue(docURI, id, attr, value) {
+    this.log(
+      "Saving " + attr + "=" + value + " for id=" + id + ", doc=" + docURI
+    );
+
+    if (!this._saveAllowed) {
+      Services.console.logStringMessage(
+        "XULStore: Changes after profile-before-change are ignored!"
+      );
+      return;
+    }
+
+    // bug 319846 -- don't save really long attributes or values.
+    if (id.length > 512 || attr.length > 512) {
+      throw Components.Exception(
+        "id or attribute name too long",
+        Cr.NS_ERROR_ILLEGAL_VALUE
+      );
+    }
+
+    if (value.length > 4096) {
+      Services.console.logStringMessage(
+        "XULStore: Warning, truncating long attribute value"
+      );
+      value = value.substr(0, 4096);
+    }
+
+    let obj = this._data;
+    if (!(docURI in obj)) {
+      obj[docURI] = {};
+    }
+    obj = obj[docURI];
+    if (!(id in obj)) {
+      obj[id] = {};
+    }
+    obj = obj[id];
+
+    // Don't set the value if it is already set to avoid saving the file.
+    if (attr in obj && obj[attr] == value) {
+      return;
+    }
+
+    obj[attr] = value; // IE, this._data[docURI][id][attr] = value;
+
+    this.markAsChanged();
+  },
+
+  hasValue(docURI, id, attr) {
+    this.log(
+      "has store value for id=" + id + ", attr=" + attr + ", doc=" + docURI
+    );
+
+    let ids = this._data[docURI];
+    if (ids) {
+      let attrs = ids[id];
+      if (attrs) {
+        return attr in attrs;
+      }
+    }
+
+    return false;
+  },
+
+  getValue(docURI, id, attr) {
+    this.log(
+      "get store value for id=" + id + ", attr=" + attr + ", doc=" + docURI
+    );
+
+    let ids = this._data[docURI];
+    if (ids) {
+      let attrs = ids[id];
+      if (attrs) {
+        return attrs[attr] || "";
+      }
+    }
+
+    return "";
+  },
+
+  removeValue(docURI, id, attr) {
+    this.log(
+      "remove store value for id=" + id + ", attr=" + attr + ", doc=" + docURI
+    );
+
+    if (!this._saveAllowed) {
+      Services.console.logStringMessage(
+        "XULStore: Changes after profile-before-change are ignored!"
+      );
+      return;
+    }
+
+    let ids = this._data[docURI];
+    if (ids) {
+      let attrs = ids[id];
+      if (attrs && attr in attrs) {
+        delete attrs[attr];
+
+        if (!Object.getOwnPropertyNames(attrs).length) {
+          delete ids[id];
+
+          if (!Object.getOwnPropertyNames(ids).length) {
+            delete this._data[docURI];
+          }
+        }
+
+        this.markAsChanged();
+      }
+    }
+  },
+
+  removeDocument(docURI) {
+    this.log("remove store values for doc=" + docURI);
+
+    if (!this._saveAllowed) {
+      Services.console.logStringMessage(
+        "XULStore: Changes after profile-before-change are ignored!"
+      );
+      return;
+    }
+
+    if (this._data[docURI]) {
+      delete this._data[docURI];
+      this.markAsChanged();
+    }
+  },
+
+  getIDsEnumerator(docURI) {
+    this.log("Getting ID enumerator for doc=" + docURI);
+
+    if (!(docURI in this._data)) {
+      return new nsStringEnumerator([]);
+    }
+
+    let result = [];
+    let ids = this._data[docURI];
+    if (ids) {
+      for (let id in this._data[docURI]) {
+        result.push(id);
+      }
+    }
+
+    return new nsStringEnumerator(result);
+  },
+
+  getAttributeEnumerator(docURI, id) {
+    this.log("Getting attribute enumerator for id=" + id + ", doc=" + docURI);
+
+    if (!(docURI in this._data) || !(id in this._data[docURI])) {
+      return new nsStringEnumerator([]);
+    }
+
+    let attrs = [];
+    for (let attr in this._data[docURI][id]) {
+      attrs.push(attr);
+    }
+
+    return new nsStringEnumerator(attrs);
+  },
+};
+
+function nsStringEnumerator(items) {
+  this._items = items;
+}
+
+nsStringEnumerator.prototype = {
+  QueryInterface: ChromeUtils.generateQI(["nsIStringEnumerator"]),
+  _nextIndex: 0,
+  [Symbol.iterator]() {
+    return this._items.values();
+  },
+  hasMore() {
+    return this._nextIndex < this._items.length;
+  },
+  getNext() {
+    if (!this.hasMore()) {
+      throw Components.Exception("", Cr.NS_ERROR_NOT_AVAILABLE);
+    }
+    return this._items[this._nextIndex++];
+  },
+};
diff --git a/toolkit/components/xulstore/components.conf b/toolkit/components/xulstore/components.conf
new file mode 100644
index 0000000000..14299ece49
--- /dev/null
+++ b/toolkit/components/xulstore/components.conf
@@ -0,0 +1,17 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+Classes = [
+    {
+        'js_name': 'xulStore',
+        'cid': '{6f46b6f4-c8b1-4bd4-a4fa-9ebbed0753ea}',
+        'contract_ids': ['@mozilla.org/xul/xulstore;1'],
+        'interfaces': ['nsIXULStore'],
+        'esModule': 'resource://gre/modules/XULStore.sys.mjs',
+        'constructor': 'XULStore',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+]
diff --git a/toolkit/components/xulstore/moz.build b/toolkit/components/xulstore/moz.build
new file mode 100644
index 0000000000..3493638a33
--- /dev/null
+++ b/toolkit/components/xulstore/moz.build
@@ -0,0 +1,25 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+with Files("**"):
+    BUG_COMPONENT = ("Toolkit", "Startup and Profile System")
+
+MOCHITEST_CHROME_MANIFESTS += ["tests/chrome/chrome.toml"]
+XPCSHELL_TESTS_MANIFESTS += ["tests/xpcshell/xpcshell.toml"]
+
+XPIDL_MODULE = "toolkit_xulstore"
+
+XPIDL_SOURCES += [
+    "nsIXULStore.idl",
+]
+
+XPCOM_MANIFESTS += [
+    "components.conf",
+]
+
+EXTRA_JS_MODULES += [
+    "XULStore.sys.mjs",
+]
diff --git a/toolkit/components/xulstore/nsIXULStore.idl b/toolkit/components/xulstore/nsIXULStore.idl
new file mode 100644
index 0000000000..832c07dc90
--- /dev/null
+++ b/toolkit/components/xulstore/nsIXULStore.idl
@@ -0,0 +1,94 @@
+/* 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/. */
+
+#include "nsISupports.idl"
+
+interface nsIStringEnumerator;
+webidl Node;
+
+/**
+ * The XUL store is used to store information related to a XUL document/application.
+ * Typically it is used to store the persisted state for the document, such as
+ * window location, toolbars that are open and nodes that are open and closed in a tree.
+ *
+ * The data is serialized to [profile directory]/xulstore.json
+ */
+[scriptable, uuid(987c4b35-c426-4dd7-ad49-3c9fa4c65d20)]
+interface nsIXULStore: nsISupports
+{
+  /**
+   * Sets a value for a specified node's attribute, except in
+   * the case below:
+   * If the value is empty and if calling `hasValue` with the node's
+   * document and ID and `attr` would return true, then the
+   * value instead gets removed from the store (see Bug 1476680).
+   *
+   * @param node - DOM node
+   * @param attr - attribute to store
+   */
+  void persist(in Node aNode, in AString attr);
+
+  /**
+   * Sets a value in the store.
+   *
+   * @param doc - document URI
+   * @param id - identifier of the node
+   * @param attr - attribute to store
+   * @param value - value of the attribute
+   */
+  void setValue(in AString doc, in AString id, in AString attr, in AString value);
+
+  /**
+   * Returns true if the store contains a value for attr.
+   *
+   * @param doc - URI of the document
+   * @param id - identifier of the node
+   * @param attr - attribute
+   */
+  bool hasValue(in AString doc, in AString id, in AString attr);
+
+  /**
+   * Retrieves a value in the store, or an empty string if it does not exist.
+   *
+   * @param doc - document URI
+   * @param id - identifier of the node
+   * @param attr - attribute to retrieve
+   *
+   * @returns the value of the attribute
+   */
+  AString getValue(in AString doc, in AString id, in AString attr);
+
+  /**
+   * Removes a value in the store.
+   *
+   * @param doc - document URI
+   * @param id - identifier of the node
+   * @param attr - attribute to remove
+   */
+  void removeValue(in AString doc, in AString id, in AString attr);
+
+  /**
+   * Removes all values related to the given document.
+   *
+   * @param doc - document URI
+   */
+  void removeDocument(in AString doc);
+
+  /**
+   * Iterates over all of the ids associated with a given document uri that
+   * have stored data.
+   *
+   * @param doc - document URI
+   */
+  nsIStringEnumerator getIDsEnumerator(in AString doc);
+
+  /**
+   * Iterates over all of the attributes associated with a given document uri
+   * and id that have stored data.
+   *
+   * @param doc - document URI
+   * @param id - identifier of the node
+   */
+  nsIStringEnumerator getAttributeEnumerator(in AString doc, in AString id);
+};
diff --git a/toolkit/components/xulstore/tests/chrome/chrome.toml b/toolkit/components/xulstore/tests/chrome/chrome.toml
new file mode 100644
index 0000000000..9675799781
--- /dev/null
+++ b/toolkit/components/xulstore/tests/chrome/chrome.toml
@@ -0,0 +1,4 @@
+[DEFAULT]
+support-files = ["window_persistence.xhtml"]
+
+["test_persistence.xhtml"]
diff --git a/toolkit/components/xulstore/tests/chrome/test_persistence.xhtml b/toolkit/components/xulstore/tests/chrome/test_persistence.xhtml
new file mode 100644
index 0000000000..b3e65fb050
--- /dev/null
+++ b/toolkit/components/xulstore/tests/chrome/test_persistence.xhtml
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+
+<window title="Persistence Tests"
+        onload="runTest()"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <script>
+    SimpleTest.waitForExplicitFinish();
+    function runTest() {
+      window.openDialog("window_persistence.xhtml", "_blank", "chrome,noopener", true, window);
+    }
+
+    function windowOpened() {
+      window.openDialog("window_persistence.xhtml", "_blank", "chrome,noopener", false, window);
+    }
+
+    function testDone() {
+      SimpleTest.finish();
+    }
+  </script>
+
+<body xmlns="http://www.w3.org/1999/xhtml">
+  <p id="display"/>
+</body>
+
+</window>
diff --git a/toolkit/components/xulstore/tests/chrome/window_persistence.xhtml b/toolkit/components/xulstore/tests/chrome/window_persistence.xhtml
new file mode 100644
index 0000000000..d474891cfc
--- /dev/null
+++ b/toolkit/components/xulstore/tests/chrome/window_persistence.xhtml
@@ -0,0 +1,67 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+
+<window title="Persistence Tests"
+        onload="opened()"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        persist="screenX screenY width height">
+
+<button id="button1" label="Button1" persist="value"/>
+<button id="button2" label="Button2" value="Normal" persist="value"/>
+<button id="button3" label="Button3" value="Normal" persist="hidden" hidden="true"/>
+
+<script>
+<![CDATA[
+
+const XULStore = Services.xulStore;
+let URI = "chrome://mochitests/content/chrome/toolkit/components/xulstore/tests/chrome/window_persistence.xhtml";
+
+function opened()
+{
+  runTest();
+}
+
+function runTest()
+{
+  var firstRun = window.arguments[0];
+  var button1 = document.getElementById("button1");
+  var button2 = document.getElementById("button2");
+  var button3 = document.getElementById("button3");
+  if (firstRun) {
+    button1.setAttribute("value", "Pressed");
+    button2.removeAttribute("value");
+
+    button2.setAttribute("foo", "bar");
+    XULStore.persist(button2, "foo");
+    is(XULStore.getValue(URI, "button2", "foo"), "bar", "attribute persisted");
+    button2.removeAttribute("foo");
+    XULStore.persist(button2, "foo");
+    is(XULStore.hasValue(URI, "button2", "foo"), false, "attribute removed");
+
+    button3.removeAttribute("hidden");
+
+    window.close();
+    window.arguments[1].windowOpened();
+  }
+  else {
+    is(button1.getAttribute("value"), "Pressed",
+       "Attribute set");
+    is(button2.hasAttribute("value"), false,
+       "Attribute cleared");
+    is(button2.hasAttribute("foo"), false,
+       "Attribute cleared");
+
+    is(button3.hasAttribute("hidden"), false,
+       "Attribute cleared");
+
+    window.close();
+    window.arguments[1].testDone();
+  }
+}
+
+function is(l, r, n) { window.arguments[1].SimpleTest.is(l,r,n); }
+
+]]></script>
+
+</window>
diff --git a/toolkit/components/xulstore/tests/xpcshell/test_XULStore.js b/toolkit/components/xulstore/tests/xpcshell/test_XULStore.js
new file mode 100644
index 0000000000..d100592e81
--- /dev/null
+++ b/toolkit/components/xulstore/tests/xpcshell/test_XULStore.js
@@ -0,0 +1,150 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/◦
+*/
+
+"use strict";
+
+var XULStore = null;
+var browserURI = "chrome://browser/content/browser.xhtml";
+var aboutURI = "about:config";
+
+function run_test() {
+  do_get_profile();
+  run_next_test();
+}
+
+function checkValue(uri, id, attr, reference) {
+  let value = XULStore.getValue(uri, id, attr);
+  Assert.equal(value, reference);
+}
+
+function checkValueExists(uri, id, attr, exists) {
+  Assert.equal(XULStore.hasValue(uri, id, attr), exists);
+}
+
+function getIDs(uri) {
+  return Array.from(XULStore.getIDsEnumerator(uri)).sort();
+}
+
+function getAttributes(uri, id) {
+  return Array.from(XULStore.getAttributeEnumerator(uri, id)).sort();
+}
+
+function checkArrays(a, b) {
+  a.sort();
+  b.sort();
+  Assert.equal(a.toString(), b.toString());
+}
+
+add_task(async function setup() {
+  // Set a value that a future test depends on manually
+  XULStore = Services.xulStore;
+  XULStore.setValue(browserURI, "main-window", "width", "994");
+});
+
+add_task(async function testTruncation() {
+  let dos = Array(8192).join("~");
+  // Long id names should trigger an exception
+  Assert.throws(
+    () => XULStore.setValue(browserURI, dos, "foo", "foo"),
+    /NS_ERROR_ILLEGAL_VALUE/
+  );
+
+  // Long attr names should trigger an exception
+  Assert.throws(
+    () => XULStore.setValue(browserURI, "foo", dos, "foo"),
+    /NS_ERROR_ILLEGAL_VALUE/
+  );
+
+  // Long values should be truncated
+  XULStore.setValue(browserURI, "dos", "dos", dos);
+  dos = XULStore.getValue(browserURI, "dos", "dos");
+  Assert.ok(dos.length == 4096);
+  XULStore.removeValue(browserURI, "dos", "dos");
+});
+
+add_task(async function testGetValue() {
+  // Get non-existing property
+  checkValue(browserURI, "side-window", "height", "");
+
+  // Get existing property
+  checkValue(browserURI, "main-window", "width", "994");
+});
+
+add_task(async function testHasValue() {
+  // Check non-existing property
+  checkValueExists(browserURI, "side-window", "height", false);
+
+  // Check existing property
+  checkValueExists(browserURI, "main-window", "width", true);
+});
+
+add_task(async function testSetValue() {
+  // Set new attribute
+  checkValue(browserURI, "side-bar", "width", "");
+  XULStore.setValue(browserURI, "side-bar", "width", "1000");
+  checkValue(browserURI, "side-bar", "width", "1000");
+  checkArrays(["main-window", "side-bar"], getIDs(browserURI));
+  checkArrays(["width"], getAttributes(browserURI, "side-bar"));
+
+  // Modify existing property
+  checkValue(browserURI, "side-bar", "width", "1000");
+  XULStore.setValue(browserURI, "side-bar", "width", "1024");
+  checkValue(browserURI, "side-bar", "width", "1024");
+  checkArrays(["main-window", "side-bar"], getIDs(browserURI));
+  checkArrays(["width"], getAttributes(browserURI, "side-bar"));
+
+  // Add another attribute
+  checkValue(browserURI, "side-bar", "height", "");
+  XULStore.setValue(browserURI, "side-bar", "height", "1000");
+  checkValue(browserURI, "side-bar", "height", "1000");
+  checkArrays(["main-window", "side-bar"], getIDs(browserURI));
+  checkArrays(["width", "height"], getAttributes(browserURI, "side-bar"));
+});
+
+add_task(async function testRemoveValue() {
+  // Remove first attribute
+  checkValue(browserURI, "side-bar", "width", "1024");
+  XULStore.removeValue(browserURI, "side-bar", "width");
+  checkValue(browserURI, "side-bar", "width", "");
+  checkValueExists(browserURI, "side-bar", "width", false);
+  checkArrays(["main-window", "side-bar"], getIDs(browserURI));
+  checkArrays(["height"], getAttributes(browserURI, "side-bar"));
+
+  // Remove second attribute
+  checkValue(browserURI, "side-bar", "height", "1000");
+  XULStore.removeValue(browserURI, "side-bar", "height");
+  checkValue(browserURI, "side-bar", "height", "");
+  checkArrays(["main-window"], getIDs(browserURI));
+
+  // Removing an attribute that doesn't exists shouldn't fail
+  XULStore.removeValue(browserURI, "main-window", "bar");
+
+  // Removing from an id that doesn't exists shouldn't fail
+  XULStore.removeValue(browserURI, "foo", "bar");
+
+  // Removing from a document that doesn't exists shouldn't fail
+  let nonDocURI = "chrome://example/content/other.xul";
+  XULStore.removeValue(nonDocURI, "foo", "bar");
+
+  // Remove all attributes in browserURI
+  XULStore.removeValue(browserURI, "addon-bar", "collapsed");
+  checkArrays([], getAttributes(browserURI, "addon-bar"));
+  XULStore.removeValue(browserURI, "main-window", "width");
+  XULStore.removeValue(browserURI, "main-window", "height");
+  XULStore.removeValue(browserURI, "main-window", "screenX");
+  XULStore.removeValue(browserURI, "main-window", "screenY");
+  XULStore.removeValue(browserURI, "main-window", "sizemode");
+  checkArrays([], getAttributes(browserURI, "main-window"));
+  XULStore.removeValue(browserURI, "sidebar-title", "value");
+  checkArrays([], getAttributes(browserURI, "sidebar-title"));
+  checkArrays([], getIDs(browserURI));
+
+  // Remove all attributes in aboutURI
+  XULStore.removeValue(aboutURI, "prefCol", "ordinal");
+  XULStore.removeValue(aboutURI, "prefCol", "sortDirection");
+  checkArrays([], getAttributes(aboutURI, "prefCol"));
+  XULStore.removeValue(aboutURI, "lockCol", "ordinal");
+  checkArrays([], getAttributes(aboutURI, "lockCol"));
+  checkArrays([], getIDs(aboutURI));
+});
diff --git a/toolkit/components/xulstore/tests/xpcshell/xpcshell.toml b/toolkit/components/xulstore/tests/xpcshell/xpcshell.toml
new file mode 100644
index 0000000000..7827962579
--- /dev/null
+++ b/toolkit/components/xulstore/tests/xpcshell/xpcshell.toml
@@ -0,0 +1,4 @@
+[DEFAULT]
+skip-if = ["os == 'android'"]
+
+["test_XULStore.js"]