1 files changed, 159 insertions, 0 deletions
diff --git a/toolkit/modules/AsyncPrefs.sys.mjs b/toolkit/modules/AsyncPrefs.sys.mjs
new file mode 100644
index 0000000000..5fa0ea6d6f
--- /dev/null
+++ b/toolkit/modules/AsyncPrefs.sys.mjs
@@ -0,0 +1,159 @@
+/* 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/. */
+
+const kInChildProcess =
+  Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT;
+
+const kAllowedPrefs = new Set([
+  // NB: please leave the testing prefs at the top, and sort the rest alphabetically if you add
+  // anything.
+  "testing.allowed-prefs.some-bool-pref",
+  "testing.allowed-prefs.some-char-pref",
+  "testing.allowed-prefs.some-int-pref",
+
+  "browser.contentblocking.report.hide_vpn_banner",
+  "browser.contentblocking.report.show_mobile_app",
+
+  "browser.shopping.experience2023.optedIn",
+  "browser.shopping.experience2023.active",
+  "browser.shopping.experience2023.ads.userEnabled",
+  "browser.shopping.experience2023.autoOpen.enabled",
+  "browser.shopping.experience2023.autoOpen.userEnabled",
+  "browser.shopping.experience2023.showKeepSidebarClosedMessage",
+  "browser.shopping.experience2023.sidebarClosedCount",
+
+  "narrate.rate",
+  "narrate.voice",
+
+  "reader.font_size",
+  "reader.font_type",
+  "reader.color_scheme",
+  "reader.content_width",
+  "reader.line_height",
+
+  "security.tls.version.enable-deprecated",
+  "security.xfocsp.errorReporting.automatic",
+
+  "network.trr.display_fallback_warning",
+]);
+
+const kPrefTypeMap = new Map([
+  ["boolean", Services.prefs.PREF_BOOL],
+  ["number", Services.prefs.PREF_INT],
+  ["string", Services.prefs.PREF_STRING],
+]);
+
+function maybeReturnErrorForReset(pref) {
+  if (!kAllowedPrefs.has(pref)) {
+    return `Resetting pref ${pref} from content is not allowed.`;
+  }
+  return false;
+}
+
+function maybeReturnErrorForSet(pref, value) {
+  if (!kAllowedPrefs.has(pref)) {
+    return `Setting pref ${pref} from content is not allowed.`;
+  }
+
+  let valueType = typeof value;
+  if (!kPrefTypeMap.has(valueType)) {
+    return `Can't set pref ${pref} to value of type ${valueType}.`;
+  }
+  let prefType = Services.prefs.getPrefType(pref);
+  if (
+    prefType != Services.prefs.PREF_INVALID &&
+    prefType != kPrefTypeMap.get(valueType)
+  ) {
+    return `Can't set pref ${pref} to a value with type ${valueType} that doesn't match the pref's type ${prefType}.`;
+  }
+  return false;
+}
+
+export class AsyncPrefsChild extends JSProcessActorChild {
+  set(pref, value) {
+    let error = maybeReturnErrorForSet(pref, value);
+    if (error) {
+      return Promise.reject(error);
+    }
+
+    return this.sendQuery("AsyncPrefs:SetPref", {
+      pref,
+      value,
+    });
+  }
+
+  reset(pref) {
+    let error = maybeReturnErrorForReset(pref);
+    if (error) {
+      return Promise.reject(error);
+    }
+
+    return this.sendQuery("AsyncPrefs:ResetPref", { pref });
+  }
+}
+
+export var AsyncPrefs = {
+  set(pref, value) {
+    if (kInChildProcess) {
+      return ChromeUtils.domProcessChild
+        .getActor("AsyncPrefs")
+        .set(pref, value);
+    }
+    return AsyncPrefsParent.set(pref, value);
+  },
+
+  reset(pref, value) {
+    if (kInChildProcess) {
+      return ChromeUtils.domProcessChild.getActor("AsyncPrefs").reset(pref);
+    }
+    return AsyncPrefsParent.reset(pref);
+  },
+};
+
+const methodForType = {
+  number: "setIntPref",
+  boolean: "setBoolPref",
+  string: "setCharPref",
+};
+
+export class AsyncPrefsParent extends JSProcessActorParent {
+  static set(pref, value) {
+    let error = maybeReturnErrorForSet(pref, value);
+    if (error) {
+      return Promise.reject(error);
+    }
+    let methodToUse = methodForType[typeof value];
+    try {
+      Services.prefs[methodToUse](pref, value);
+    } catch (ex) {
+      console.error(ex);
+      return Promise.reject(ex.message);
+    }
+
+    return Promise.resolve(value);
+  }
+
+  static reset(pref) {
+    let error = maybeReturnErrorForReset(pref);
+    if (error) {
+      return Promise.reject(error);
+    }
+
+    try {
+      Services.prefs.clearUserPref(pref);
+    } catch (ex) {
+      console.error(ex);
+      return Promise.reject(ex.message);
+    }
+
+    return Promise.resolve();
+  }
+
+  receiveMessage(msg) {
+    if (msg.name == "AsyncPrefs:SetPref") {
+      return AsyncPrefsParent.set(msg.data.pref, msg.data.value);
+    }
+    return AsyncPrefsParent.reset(msg.data.pref);
+  }
+}