Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

32 files changed, 1941 insertions, 0 deletions

diff --git a/extensions/pref/autoconfig/moz.build b/extensions/pref/autoconfig/moz.build
new file mode 100644
index 0000000000..a8292ea733
--- /dev/null
+++ b/extensions/pref/autoconfig/moz.build
@@ -0,0 +1,11 @@
+# -*- 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/.
+
+DIRS += ["src"]
+
+XPCSHELL_TESTS_MANIFESTS += ["test/unit/xpcshell.ini", "test/unit/xpcshell_snap.ini"]
+
+MARIONETTE_UNIT_MANIFESTS += ["test/marionette/manifest.ini"]
diff --git a/extensions/pref/autoconfig/src/components.conf b/extensions/pref/autoconfig/src/components.conf
new file mode 100644
index 0000000000..41de352694
--- /dev/null
+++ b/extensions/pref/autoconfig/src/components.conf
@@ -0,0 +1,21 @@
+# -*- 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 = [
+    {
+        'cid': '{ba5bc4c6-1dd1-11b2-bb89-b844c6ec0339}',
+        'contract_ids': ['@mozilla.org/readconfig;1'],
+        'type': 'nsReadConfig',
+        'headers': ['/extensions/pref/autoconfig/src/nsReadConfig.h'],
+        'init_method': 'Init',
+        'categories': {
+            'pref-config-startup': {
+                'name': 'ReadConfig Module',
+                'backgroundtasks': BackgroundTasksSelector.ALL_TASKS,
+            },
+        },
+    },
+]
diff --git a/extensions/pref/autoconfig/src/moz.build b/extensions/pref/autoconfig/src/moz.build
new file mode 100644
index 0000000000..12722cf6d7
--- /dev/null
+++ b/extensions/pref/autoconfig/src/moz.build
@@ -0,0 +1,21 @@
+# -*- 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/.
+
+UNIFIED_SOURCES += [
+    "nsAutoConfig.cpp",
+    "nsJSConfigTriggers.cpp",
+    "nsReadConfig.cpp",
+]
+
+XPCOM_MANIFESTS += [
+    "components.conf",
+]
+
+FINAL_LIBRARY = "xul"
+
+FINAL_TARGET_FILES.defaults.autoconfig += [
+    "prefcalls.js",
+]
diff --git a/extensions/pref/autoconfig/src/nsAutoConfig.cpp b/extensions/pref/autoconfig/src/nsAutoConfig.cpp
new file mode 100644
index 0000000000..907d4b7646
--- /dev/null
+++ b/extensions/pref/autoconfig/src/nsAutoConfig.cpp
@@ -0,0 +1,464 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "mozilla/ResultExtensions.h"
+#include "nsAutoConfig.h"
+#include "nsJSConfigTriggers.h"
+
+#include "nsIURI.h"
+#include "nsIHttpChannel.h"
+#include "nsThreadUtils.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsIObserverService.h"
+#include "nsLiteralString.h"
+#include "nsIPromptService.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsIPrefBranch.h"
+#include "nsIPrefService.h"
+#include "nsIStringBundle.h"
+#include "nsContentUtils.h"
+#include "nsCRT.h"
+#include "nsNetCID.h"
+#include "nsNetUtil.h"
+#include "nspr.h"
+#include <algorithm>
+
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/Logging.h"
+#include "mozilla/SpinEventLoopUntil.h"
+
+using mozilla::LogLevel;
+
+mozilla::LazyLogModule MCD("MCD");
+
+// nsISupports Implementation
+
+NS_IMPL_ISUPPORTS(nsAutoConfig, nsITimerCallback, nsIStreamListener,
+                  nsIObserver, nsIRequestObserver, nsISupportsWeakReference,
+                  nsINamed)
+
+nsAutoConfig::nsAutoConfig() {}
+
+nsresult nsAutoConfig::Init() {
+  // member initializers and constructor code
+
+  nsresult rv;
+  mLoaded = false;
+
+  // Registering the object as an observer to the profile-after-change topic
+  nsCOMPtr<nsIObserverService> observerService =
+      do_GetService("@mozilla.org/observer-service;1", &rv);
+  if (NS_FAILED(rv)) return rv;
+
+  rv = observerService->AddObserver(this, "profile-after-change", true);
+
+  return rv;
+}
+
+nsAutoConfig::~nsAutoConfig() {}
+
+void nsAutoConfig::SetConfigURL(const char* aConfigURL) {
+  mConfigURL.Assign(aConfigURL);
+}
+
+NS_IMETHODIMP
+nsAutoConfig::OnStartRequest(nsIRequest* request) { return NS_OK; }
+
+NS_IMETHODIMP
+nsAutoConfig::OnDataAvailable(nsIRequest* request, nsIInputStream* aIStream,
+                              uint64_t aSourceOffset, uint32_t aLength) {
+  uint32_t amt, size;
+  nsresult rv;
+  char buf[1024];
+
+  while (aLength) {
+    size = std::min<size_t>(aLength, sizeof(buf));
+    rv = aIStream->Read(buf, size, &amt);
+    if (NS_FAILED(rv)) return rv;
+    mBuf.Append(buf, amt);
+    aLength -= amt;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsAutoConfig::OnStopRequest(nsIRequest* request, nsresult aStatus) {
+  nsresult rv;
+
+  // If the request is failed, go read the failover.jsc file
+  if (NS_FAILED(aStatus)) {
+    MOZ_LOG(MCD, LogLevel::Debug,
+            ("mcd request failed with status %" PRIx32 "\n",
+             static_cast<uint32_t>(aStatus)));
+    return readOfflineFile();
+  }
+
+  // Checking for the http response, if failure go read the failover file.
+  nsCOMPtr<nsIHttpChannel> pHTTPCon(do_QueryInterface(request));
+  if (pHTTPCon) {
+    uint32_t httpStatus;
+    rv = pHTTPCon->GetResponseStatus(&httpStatus);
+    if (NS_FAILED(rv) || httpStatus != 200) {
+      MOZ_LOG(MCD, LogLevel::Debug,
+              ("mcd http request failed with status %x\n", httpStatus));
+      return readOfflineFile();
+    }
+  }
+
+  // Send the autoconfig.jsc to javascript engine.
+
+  rv = EvaluateAdminConfigScript(mBuf.get(), mBuf.Length(), nullptr, false,
+                                 true, false);
+  if (NS_SUCCEEDED(rv)) {
+    // Write the autoconfig.jsc to failover.jsc (cached copy)
+    rv = writeFailoverFile();
+
+    if (NS_FAILED(rv)) NS_WARNING("Error writing failover.jsc file");
+
+    // Releasing the lock to allow the main thread to start execution
+    mLoaded = true;
+
+    return NS_OK;
+  }
+  // there is an error in parsing of the autoconfig file.
+  NS_WARNING(
+      "Error reading autoconfig.jsc from the network, reading the offline "
+      "version");
+  return readOfflineFile();
+}
+
+// Notify method as a TimerCallBack function
+NS_IMETHODIMP nsAutoConfig::Notify(nsITimer* timer) {
+  downloadAutoConfig();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsAutoConfig::GetName(nsACString& aName) {
+  aName.AssignLiteral("nsAutoConfig");
+  return NS_OK;
+}
+
+/* Observe() is called twice: once at the instantiation time and other
+   after the profile is set. It doesn't do anything but return NS_OK during the
+   creation time. Second time it calls  downloadAutoConfig().
+*/
+
+NS_IMETHODIMP nsAutoConfig::Observe(nsISupports* aSubject, const char* aTopic,
+                                    const char16_t* someData) {
+  nsresult rv = NS_OK;
+  if (!nsCRT::strcmp(aTopic, "profile-after-change")) {
+    // We will be calling downloadAutoConfig even if there is no profile
+    // name. Nothing will be passed as a parameter to the URL and the
+    // default case will be picked up by the script.
+
+    rv = downloadAutoConfig();
+  }
+
+  return rv;
+}
+
+nsresult nsAutoConfig::downloadAutoConfig() {
+  nsresult rv;
+  nsAutoCString emailAddr;
+  static bool firstTime = true;
+
+  if (mConfigURL.IsEmpty()) {
+    MOZ_LOG(MCD, LogLevel::Debug,
+            ("global config url is empty - did you set "
+             "autoadmin.global_config_url?\n"));
+    NS_WARNING("AutoConfig called without global_config_url");
+    return NS_OK;
+  }
+
+  // If there is an email address appended as an argument to the ConfigURL
+  // in the previous read, we need to remove it when timer kicks in and
+  // downloads the autoconfig file again.
+  // If necessary, the email address will be added again as an argument.
+  int32_t index = mConfigURL.RFindChar((char16_t)'?');
+  if (index != -1) mConfigURL.Truncate(index);
+
+  // Clean up the previous read, the new read is going to use the same buffer
+  if (!mBuf.IsEmpty()) mBuf.Truncate(0);
+
+  // Get the preferences branch and save it to the member variable
+  if (!mPrefBranch) {
+    nsCOMPtr<nsIPrefService> prefs =
+        do_GetService(NS_PREFSERVICE_CONTRACTID, &rv);
+    if (NS_FAILED(rv)) return rv;
+
+    rv = prefs->GetBranch(nullptr, getter_AddRefs(mPrefBranch));
+    if (NS_FAILED(rv)) return rv;
+  }
+
+  // Check to see if the network is online/offline
+  nsCOMPtr<nsIIOService> ios = do_GetService(NS_IOSERVICE_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) return rv;
+
+  bool offline;
+  rv = ios->GetOffline(&offline);
+  if (NS_FAILED(rv)) return rv;
+
+  if (offline) {
+    bool offlineFailover;
+    rv = mPrefBranch->GetBoolPref("autoadmin.offline_failover",
+                                  &offlineFailover);
+    // Read the failover.jsc if the network is offline and the pref says so
+    if (NS_SUCCEEDED(rv) && offlineFailover) return readOfflineFile();
+  }
+
+  /* Append user's identity at the end of the URL if the pref says so.
+     First we are checking for the user's email address but if it is not
+     available in the case where the client is used without messenger, user's
+     profile name will be used as an unique identifier
+  */
+  bool appendMail;
+  rv = mPrefBranch->GetBoolPref("autoadmin.append_emailaddr", &appendMail);
+  if (NS_SUCCEEDED(rv) && appendMail) {
+    rv = getEmailAddr(emailAddr);
+    if (NS_SUCCEEDED(rv) && emailAddr.get()) {
+      /* Adding the unique identifier at the end of autoconfig URL.
+         In this case the autoconfig URL is a script and
+         emailAddr as passed as an argument
+      */
+      mConfigURL.Append('?');
+      mConfigURL.Append(emailAddr);
+    }
+  }
+
+  // create a new url
+  nsCOMPtr<nsIURI> url;
+  nsCOMPtr<nsIChannel> channel;
+
+  rv = NS_NewURI(getter_AddRefs(url), mConfigURL);
+  if (NS_FAILED(rv)) {
+    MOZ_LOG(
+        MCD, LogLevel::Debug,
+        ("failed to create URL - is autoadmin.global_config_url valid? - %s\n",
+         mConfigURL.get()));
+    return rv;
+  }
+
+  MOZ_LOG(MCD, LogLevel::Debug, ("running MCD url %s\n", mConfigURL.get()));
+  // open a channel for the url
+  rv = NS_NewChannel(
+      getter_AddRefs(channel), url, nsContentUtils::GetSystemPrincipal(),
+      nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+      nsIContentPolicy::TYPE_OTHER,
+      nullptr,  // nsICookieJarSettings
+      nullptr,  // PerformanceStorage
+      nullptr,  // loadGroup
+      nullptr,  // aCallbacks
+      nsIRequest::INHIBIT_PERSISTENT_CACHING | nsIRequest::LOAD_BYPASS_CACHE);
+
+  if (NS_FAILED(rv)) return rv;
+
+  rv = channel->AsyncOpen(this);
+  if (NS_FAILED(rv)) {
+    readOfflineFile();
+    return rv;
+  }
+
+  // Set a repeating timer if the pref is set.
+  // This is to be done only once.
+  // Also We are having the event queue processing only for the startup
+  // It is not needed with the repeating timer.
+  if (firstTime) {
+    firstTime = false;
+
+    /* process events until we're finished. AutoConfig.jsc reading needs
+       to be finished before the browser starts loading up
+       We are waiting for the mLoaded which will be set through
+       onStopRequest or readOfflineFile methods
+       There is a possibility of deadlock so we need to make sure
+       that mLoaded will be set to true in any case (success/failure)
+    */
+
+    if (!mozilla::SpinEventLoopUntil("nsAutoConfig::downloadAutoConfig"_ns,
+                                     [&]() { return mLoaded; })) {
+      return NS_ERROR_FAILURE;
+    }
+
+    int32_t minutes;
+    rv = mPrefBranch->GetIntPref("autoadmin.refresh_interval", &minutes);
+    if (NS_SUCCEEDED(rv) && minutes > 0) {
+      // Create a new timer and pass this nsAutoConfig
+      // object as a timer callback.
+      MOZ_TRY_VAR(mTimer,
+                  NS_NewTimerWithCallback(this, minutes * 60 * 1000,
+                                          nsITimer::TYPE_REPEATING_SLACK));
+    }
+  }  // first_time
+
+  return NS_OK;
+}  // nsPref::downloadAutoConfig()
+
+nsresult nsAutoConfig::readOfflineFile() {
+  nsresult rv;
+
+  /* Releasing the lock to allow main thread to start
+     execution. At this point we do not need to stall
+     the thread since all network activities are done.
+  */
+  mLoaded = true;
+
+  bool failCache;
+  rv = mPrefBranch->GetBoolPref("autoadmin.failover_to_cached", &failCache);
+  if (NS_SUCCEEDED(rv) && !failCache) {
+    // disable network connections and return.
+
+    nsCOMPtr<nsIIOService> ios = do_GetService(NS_IOSERVICE_CONTRACTID, &rv);
+    if (NS_FAILED(rv)) return rv;
+
+    bool offline;
+    rv = ios->GetOffline(&offline);
+    if (NS_FAILED(rv)) return rv;
+
+    if (!offline) {
+      rv = ios->SetOffline(true);
+      if (NS_FAILED(rv)) return rv;
+    }
+
+    // lock the "network.online" prference so user cannot toggle back to
+    // online mode.
+    rv = mPrefBranch->SetBoolPref("network.online", false);
+    if (NS_FAILED(rv)) return rv;
+
+    mPrefBranch->LockPref("network.online");
+    return NS_OK;
+  }
+
+  /* faiover_to_cached is set to true so
+     Open the file and read the content.
+     execute the javascript file
+  */
+
+  nsCOMPtr<nsIFile> failoverFile;
+  rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR,
+                              getter_AddRefs(failoverFile));
+  if (NS_FAILED(rv)) return rv;
+
+  failoverFile->AppendNative("failover.jsc"_ns);
+  rv = evaluateLocalFile(failoverFile);
+  if (NS_FAILED(rv))
+    NS_WARNING("Couldn't open failover.jsc, going back to default prefs");
+  return NS_OK;
+}
+
+nsresult nsAutoConfig::evaluateLocalFile(nsIFile* file) {
+  nsresult rv;
+  nsCOMPtr<nsIInputStream> inStr;
+
+  rv = NS_NewLocalFileInputStream(getter_AddRefs(inStr), file);
+  if (NS_FAILED(rv)) return rv;
+
+  int64_t fileSize;
+  file->GetFileSize(&fileSize);
+  uint32_t fs = fileSize;  // Converting 64 bit structure to unsigned int
+  char* buf = (char*)malloc(fs * sizeof(char));
+  if (!buf) return NS_ERROR_OUT_OF_MEMORY;
+
+  uint32_t amt = 0;
+  rv = inStr->Read(buf, fs, &amt);
+  if (NS_SUCCEEDED(rv)) {
+    EvaluateAdminConfigScript(buf, fs, nullptr, false, true, false);
+  }
+  inStr->Close();
+  free(buf);
+  return rv;
+}
+
+nsresult nsAutoConfig::writeFailoverFile() {
+  nsresult rv;
+  nsCOMPtr<nsIFile> failoverFile;
+  nsCOMPtr<nsIOutputStream> outStr;
+  uint32_t amt;
+
+  rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR,
+                              getter_AddRefs(failoverFile));
+  if (NS_FAILED(rv)) return rv;
+
+  failoverFile->AppendNative("failover.jsc"_ns);
+
+  rv = NS_NewLocalFileOutputStream(getter_AddRefs(outStr), failoverFile);
+  if (NS_FAILED(rv)) return rv;
+  rv = outStr->Write(mBuf.get(), mBuf.Length(), &amt);
+  outStr->Close();
+  return rv;
+}
+
+nsresult nsAutoConfig::getEmailAddr(nsACString& emailAddr) {
+  nsresult rv;
+  nsAutoCString prefValue;
+
+  /* Getting an email address through set of three preferences:
+     First getting a default account with
+     "mail.accountmanager.defaultaccount"
+     second getting an associated id with the default account
+     Third getting an email address with id
+  */
+
+  rv =
+      mPrefBranch->GetCharPref("mail.accountmanager.defaultaccount", prefValue);
+  if (NS_SUCCEEDED(rv) && !prefValue.IsEmpty()) {
+    emailAddr = "mail.account."_ns + prefValue + ".identities"_ns;
+    rv = mPrefBranch->GetCharPref(PromiseFlatCString(emailAddr).get(),
+                                  prefValue);
+    if (NS_FAILED(rv) || prefValue.IsEmpty())
+      return PromptForEMailAddress(emailAddr);
+    int32_t commandIndex = prefValue.FindChar(',');
+    if (commandIndex != kNotFound) prefValue.Truncate(commandIndex);
+    emailAddr = "mail.identity."_ns + prefValue + ".useremail"_ns;
+    rv = mPrefBranch->GetCharPref(PromiseFlatCString(emailAddr).get(),
+                                  prefValue);
+    if (NS_FAILED(rv) || prefValue.IsEmpty())
+      return PromptForEMailAddress(emailAddr);
+    emailAddr = prefValue;
+  } else {
+    // look for 4.x pref in case we just migrated.
+    rv = mPrefBranch->GetCharPref("mail.identity.useremail", prefValue);
+    if (NS_SUCCEEDED(rv) && !prefValue.IsEmpty())
+      emailAddr = prefValue;
+    else
+      PromptForEMailAddress(emailAddr);
+  }
+
+  return NS_OK;
+}
+
+nsresult nsAutoConfig::PromptForEMailAddress(nsACString& emailAddress) {
+  nsresult rv;
+  nsCOMPtr<nsIPromptService> promptService =
+      do_GetService("@mozilla.org/prompter;1", &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIStringBundleService> bundleService =
+      do_GetService(NS_STRINGBUNDLE_CONTRACTID, &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIStringBundle> bundle;
+  rv = bundleService->CreateBundle(
+      "chrome://autoconfig/locale/autoconfig.properties",
+      getter_AddRefs(bundle));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoString title;
+  rv = bundle->GetStringFromName("emailPromptTitle", title);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoString err;
+  rv = bundle->GetStringFromName("emailPromptMsg", err);
+  NS_ENSURE_SUCCESS(rv, rv);
+  bool check = false;
+  nsString emailResult;
+  bool success;
+  rv = promptService->Prompt(nullptr, title.get(), err.get(),
+                             getter_Copies(emailResult), nullptr, &check,
+                             &success);
+  if (!success) return NS_ERROR_FAILURE;
+  NS_ENSURE_SUCCESS(rv, rv);
+  LossyCopyUTF16toASCII(emailResult, emailAddress);
+  return NS_OK;
+}
diff --git a/extensions/pref/autoconfig/src/nsAutoConfig.h b/extensions/pref/autoconfig/src/nsAutoConfig.h
new file mode 100644
index 0000000000..3a78239286
--- /dev/null
+++ b/extensions/pref/autoconfig/src/nsAutoConfig.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef nsAutoConfig_h
+#define nsAutoConfig_h
+
+#include "nsITimer.h"
+#include "nsIFile.h"
+#include "nsINamed.h"
+#include "nsIObserver.h"
+#include "nsIStreamListener.h"
+#include "nsWeakReference.h"
+#include "nsString.h"
+
+class nsIPrefBranch;
+
+class nsAutoConfig final : public nsITimerCallback,
+                           public nsIStreamListener,
+                           public nsIObserver,
+                           public nsSupportsWeakReference,
+                           public nsINamed
+
+{
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIREQUESTOBSERVER
+  NS_DECL_NSISTREAMLISTENER
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSINAMED
+
+  nsAutoConfig();
+  nsresult Init();
+
+  void SetConfigURL(const char* aConfigURL);
+
+ protected:
+  virtual ~nsAutoConfig();
+  nsresult downloadAutoConfig();
+  nsresult readOfflineFile();
+  nsresult evaluateLocalFile(nsIFile* file);
+  nsresult writeFailoverFile();
+  nsresult getEmailAddr(nsACString& emailAddr);
+  nsresult PromptForEMailAddress(nsACString& emailAddress);
+  nsCString mBuf;
+  nsCOMPtr<nsIPrefBranch> mPrefBranch;
+  bool mLoaded;
+  nsCOMPtr<nsITimer> mTimer;
+  nsCString mConfigURL;
+};
+
+#endif
diff --git a/extensions/pref/autoconfig/src/nsJSConfigTriggers.cpp b/extensions/pref/autoconfig/src/nsJSConfigTriggers.cpp
new file mode 100644
index 0000000000..e0b4324f40
--- /dev/null
+++ b/extensions/pref/autoconfig/src/nsJSConfigTriggers.cpp
@@ -0,0 +1,170 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "nsJSConfigTriggers.h"
+
+#include "jsapi.h"
+#include "nsIXPConnect.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nspr.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/NullPrincipal.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/ChromeUtilsBinding.h"
+#include "nsContentUtils.h"
+#include "nsJSPrincipals.h"
+#include "nsIScriptError.h"
+#include "js/PropertyAndElement.h"  // JS_DefineProperty
+#include "js/Wrapper.h"
+#include "mozilla/Utf8.h"
+
+extern mozilla::LazyLogModule MCD;
+using mozilla::AutoSafeJSContext;
+using mozilla::IsUtf8;
+using mozilla::NullPrincipal;
+using mozilla::dom::AutoJSAPI;
+
+//*****************************************************************************
+
+static JS::PersistentRooted<JSObject*> autoconfigSystemSb;
+static JS::PersistentRooted<JSObject*> autoconfigSb;
+bool sandboxEnabled;
+
+nsresult CentralizedAdminPrefManagerInit(bool aSandboxEnabled) {
+  // If the sandbox is already created, no need to create it again.
+  if (autoconfigSb.initialized()) return NS_OK;
+
+  sandboxEnabled = aSandboxEnabled;
+
+  // Grab XPConnect.
+  nsCOMPtr<nsIXPConnect> xpc = nsIXPConnect::XPConnect();
+
+  // Grab the system principal.
+  nsCOMPtr<nsIPrincipal> principal;
+  nsContentUtils::GetSecurityManager()->GetSystemPrincipal(
+      getter_AddRefs(principal));
+
+  // Create a sandbox.
+  AutoSafeJSContext cx;
+  JS::Rooted<JSObject*> sandbox(cx);
+  nsresult rv = xpc->CreateSandbox(cx, principal, sandbox.address());
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Unwrap, store and root the sandbox.
+  NS_ENSURE_STATE(sandbox);
+  autoconfigSystemSb.init(cx, js::UncheckedUnwrap(sandbox));
+
+  // Create an unprivileged sandbox.
+  principal = NullPrincipal::CreateWithoutOriginAttributes();
+  rv = xpc->CreateSandbox(cx, principal, sandbox.address());
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  autoconfigSb.init(cx, js::UncheckedUnwrap(sandbox));
+
+  // Define gSandbox on system sandbox.
+  JSAutoRealm ar(cx, autoconfigSystemSb);
+
+  JS::Rooted<JS::Value> value(cx, JS::ObjectValue(*sandbox));
+
+  if (!JS_WrapValue(cx, &value) ||
+      !JS_DefineProperty(cx, autoconfigSystemSb, "gSandbox", value,
+                         JSPROP_ENUMERATE)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Define ChromeUtils for ChromeUtils.import.
+  if (!mozilla::dom::ChromeUtils_Binding::GetConstructorObject(cx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+nsresult CentralizedAdminPrefManagerFinish() {
+  if (autoconfigSb.initialized()) {
+    AutoSafeJSContext cx;
+    autoconfigSb.reset();
+    autoconfigSystemSb.reset();
+    JS_MaybeGC(cx);
+  }
+  return NS_OK;
+}
+
+nsresult EvaluateAdminConfigScript(const char* js_buffer, size_t length,
+                                   const char* filename, bool globalContext,
+                                   bool callbacks, bool skipFirstLine,
+                                   bool isPrivileged) {
+  if (!sandboxEnabled) {
+    isPrivileged = true;
+  }
+  return EvaluateAdminConfigScript(
+      isPrivileged ? autoconfigSystemSb : autoconfigSb, js_buffer, length,
+      filename, globalContext, callbacks, skipFirstLine);
+}
+
+nsresult EvaluateAdminConfigScript(JS::Handle<JSObject*> sandbox,
+                                   const char* js_buffer, size_t length,
+                                   const char* filename, bool globalContext,
+                                   bool callbacks, bool skipFirstLine) {
+  if (skipFirstLine) {
+    /* In order to protect the privacy of the JavaScript preferences file
+     * from loading by the browser, we make the first line unparseable
+     * by JavaScript. We must skip that line here before executing
+     * the JavaScript code.
+     */
+    unsigned int i = 0;
+    while (i < length) {
+      char c = js_buffer[i++];
+      if (c == '\r') {
+        if (js_buffer[i] == '\n') i++;
+        break;
+      }
+      if (c == '\n') break;
+    }
+
+    length -= i;
+    js_buffer += i;
+  }
+
+  // Grab XPConnect.
+  nsCOMPtr<nsIXPConnect> xpc = nsIXPConnect::XPConnect();
+
+  AutoJSAPI jsapi;
+  if (!jsapi.Init(sandbox)) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  JSContext* cx = jsapi.cx();
+
+  nsAutoCString script(js_buffer, length);
+  JS::Rooted<JS::Value> v(cx);
+
+  nsString convertedScript;
+  bool isUTF8 = IsUtf8(script);
+  if (isUTF8) {
+    CopyUTF8toUTF16(script, convertedScript);
+  } else {
+    nsContentUtils::ReportToConsoleNonLocalized(
+        nsLiteralString(
+            u"Your AutoConfig file is ASCII. Please convert it to UTF-8."),
+        nsIScriptError::warningFlag, "autoconfig"_ns, nullptr);
+    /* If the length is 0, the conversion failed. Fallback to ASCII */
+    convertedScript = NS_ConvertASCIItoUTF16(script);
+  }
+  {
+    JSAutoRealm ar(cx, autoconfigSystemSb);
+    JS::Rooted<JS::Value> value(cx, JS::BooleanValue(isUTF8));
+    if (!JS_DefineProperty(cx, autoconfigSystemSb, "gIsUTF8", value,
+                           JSPROP_ENUMERATE)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+  }
+  nsresult rv =
+      xpc->EvalInSandboxObject(convertedScript, filename, cx, sandbox, &v);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return NS_OK;
+}
diff --git a/extensions/pref/autoconfig/src/nsJSConfigTriggers.h b/extensions/pref/autoconfig/src/nsJSConfigTriggers.h
new file mode 100644
index 0000000000..1f7c3804b9
--- /dev/null
+++ b/extensions/pref/autoconfig/src/nsJSConfigTriggers.h
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsConfigTriggers_h
+#define nsConfigTriggers_h
+
+#include "nscore.h"
+#include "js/TypeDecls.h"
+
+nsresult EvaluateAdminConfigScript(const char* js_buffer, size_t length,
+                                   const char* filename, bool bGlobalContext,
+                                   bool bCallbacks, bool skipFirstLine,
+                                   bool isPrivileged = false);
+
+nsresult EvaluateAdminConfigScript(JS::Handle<JSObject*> sandbox,
+                                   const char* js_buffer, size_t length,
+                                   const char* filename, bool bGlobalContext,
+                                   bool bCallbacks, bool skipFirstLine);
+
+#endif  // nsConfigTriggers_h
diff --git a/extensions/pref/autoconfig/src/nsReadConfig.cpp b/extensions/pref/autoconfig/src/nsReadConfig.cpp
new file mode 100644
index 0000000000..3da68faac6
--- /dev/null
+++ b/extensions/pref/autoconfig/src/nsReadConfig.cpp
@@ -0,0 +1,312 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "nsReadConfig.h"
+#include "nsJSConfigTriggers.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/Components.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsIAppStartup.h"
+#include "nsIChannel.h"
+#include "nsContentUtils.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsIFile.h"
+#include "nsIInputStream.h"
+#include "nsIObserverService.h"
+#include "nsIPrefBranch.h"
+#include "nsIPrefService.h"
+#include "nsIPromptService.h"
+#include "nsIStringBundle.h"
+#include "nsNetUtil.h"
+#include "nsString.h"
+#include "nsCRT.h"
+#include "nspr.h"
+#include "nsXULAppAPI.h"
+
+#if defined(MOZ_WIDGET_GTK)
+#  include "mozilla/WidgetUtilsGtk.h"
+#endif  // defined(MOZ_WIDGET_GTK)
+
+using namespace mozilla;
+
+extern bool sandboxEnabled;
+
+extern mozilla::LazyLogModule MCD;
+
+extern nsresult CentralizedAdminPrefManagerInit(bool aSandboxEnabled);
+extern nsresult CentralizedAdminPrefManagerFinish();
+
+static nsresult DisplayError(void) {
+  nsresult rv;
+
+  nsCOMPtr<nsIPromptService> promptService =
+      do_GetService("@mozilla.org/prompter;1");
+  if (!promptService) return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsIStringBundleService> bundleService =
+      do_GetService(NS_STRINGBUNDLE_CONTRACTID);
+  if (!bundleService) return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsIStringBundle> bundle;
+  bundleService->CreateBundle(
+      "chrome://autoconfig/locale/autoconfig.properties",
+      getter_AddRefs(bundle));
+  if (!bundle) return NS_ERROR_FAILURE;
+
+  nsAutoString title;
+  rv = bundle->GetStringFromName("readConfigTitle", title);
+  if (NS_FAILED(rv)) return rv;
+
+  nsAutoString err;
+  rv = bundle->GetStringFromName("readConfigMsg", err);
+  if (NS_FAILED(rv)) return rv;
+
+  return promptService->Alert(nullptr, title.get(), err.get());
+}
+
+// nsISupports Implementation
+
+NS_IMPL_ISUPPORTS(nsReadConfig, nsIObserver)
+
+nsReadConfig::nsReadConfig() : mRead(false) {}
+
+nsresult nsReadConfig::Init() {
+  nsresult rv;
+
+  nsCOMPtr<nsIObserverService> observerService =
+      do_GetService("@mozilla.org/observer-service;1", &rv);
+
+  if (observerService) {
+    rv =
+        observerService->AddObserver(this, NS_PREFSERVICE_READ_TOPIC_ID, false);
+  }
+  return (rv);
+}
+
+nsReadConfig::~nsReadConfig() { CentralizedAdminPrefManagerFinish(); }
+
+NS_IMETHODIMP nsReadConfig::Observe(nsISupports* aSubject, const char* aTopic,
+                                    const char16_t* someData) {
+  nsresult rv = NS_OK;
+
+  if (!nsCRT::strcmp(aTopic, NS_PREFSERVICE_READ_TOPIC_ID)) {
+    rv = readConfigFile();
+    // Don't show error alerts if the sandbox is enabled, just show
+    // sandbox warning.
+    if (NS_FAILED(rv)) {
+      if (sandboxEnabled) {
+        nsContentUtils::ReportToConsoleNonLocalized(
+            u"Autoconfig is sandboxed by default. See "
+            "https://support.mozilla.org/products/"
+            "firefox-enterprise for more information."_ns,
+            nsIScriptError::warningFlag, "autoconfig"_ns, nullptr);
+      } else {
+        rv = DisplayError();
+        if (NS_FAILED(rv)) {
+          nsCOMPtr<nsIAppStartup> appStartup =
+              components::AppStartup::Service();
+          if (appStartup) {
+            bool userAllowedQuit = true;
+            appStartup->Quit(nsIAppStartup::eAttemptQuit, 0, &userAllowedQuit);
+          }
+        }
+      }
+    }
+  }
+  return rv;
+}
+
+/**
+ * This is the blocklist for known bad autoconfig files.
+ */
+static const char* gBlockedConfigs[] = {"dsengine.cfg"};
+
+nsresult nsReadConfig::readConfigFile() {
+  nsresult rv = NS_OK;
+  nsAutoCString lockFileName;
+  nsAutoCString lockVendor;
+  uint32_t fileNameLen = 0;
+
+  nsCOMPtr<nsIPrefBranch> defaultPrefBranch;
+  nsCOMPtr<nsIPrefService> prefService =
+      do_GetService(NS_PREFSERVICE_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) return rv;
+
+  rv =
+      prefService->GetDefaultBranch(nullptr, getter_AddRefs(defaultPrefBranch));
+  if (NS_FAILED(rv)) return rv;
+
+  constexpr auto channel = nsLiteralCString{MOZ_STRINGIFY(MOZ_UPDATE_CHANNEL)};
+
+  bool sandboxEnabled =
+      channel.EqualsLiteral("beta") || channel.EqualsLiteral("release");
+
+  mozilla::Unused << defaultPrefBranch->GetBoolPref(
+      "general.config.sandbox_enabled", &sandboxEnabled);
+
+  rv = defaultPrefBranch->GetCharPref("general.config.filename", lockFileName);
+
+  if (NS_FAILED(rv)) return rv;
+
+  MOZ_LOG(MCD, LogLevel::Debug,
+          ("general.config.filename = %s\n", lockFileName.get()));
+
+  for (size_t index = 0, len = mozilla::ArrayLength(gBlockedConfigs);
+       index < len; ++index) {
+    if (lockFileName == gBlockedConfigs[index]) {
+      // This is NS_OK because we don't want to show an error to the user
+      return rv;
+    }
+  }
+
+  // This needs to be read only once.
+  //
+  if (!mRead) {
+    // Initiate the new JS Context for Preference management
+
+    rv = CentralizedAdminPrefManagerInit(sandboxEnabled);
+    if (NS_FAILED(rv)) return rv;
+
+    // Open and evaluate function calls to set/lock/unlock prefs
+    rv = openAndEvaluateJSFile("prefcalls.js", 0, false, false);
+    if (NS_FAILED(rv)) return rv;
+
+    mRead = true;
+  }
+  // If the lockFileName is nullptr return ok, because no lockFile will be used
+
+  // Once the config file is read, we should check that the vendor name
+  // is consistent By checking for the vendor name after reading the config
+  // file we allow for the preference to be set (and locked) by the creator
+  // of the cfg file meaning the file can not be renamed (successfully).
+
+  nsCOMPtr<nsIPrefBranch> prefBranch;
+  rv = prefService->GetBranch(nullptr, getter_AddRefs(prefBranch));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  int32_t obscureValue = 0;
+  (void)defaultPrefBranch->GetIntPref("general.config.obscure_value",
+                                      &obscureValue);
+  MOZ_LOG(MCD, LogLevel::Debug,
+          ("evaluating .cfg file %s with obscureValue %d\n", lockFileName.get(),
+           obscureValue));
+  rv = openAndEvaluateJSFile(lockFileName.get(), obscureValue, true, true);
+  if (NS_FAILED(rv)) {
+    MOZ_LOG(MCD, LogLevel::Debug,
+            ("error evaluating .cfg file %s %" PRIx32 "\n", lockFileName.get(),
+             static_cast<uint32_t>(rv)));
+    return rv;
+  }
+
+  rv = prefBranch->GetCharPref("general.config.filename", lockFileName);
+  if (NS_FAILED(rv))
+    // There is NO REASON we should ever get here. This is POST reading
+    // of the config file.
+    return NS_ERROR_FAILURE;
+
+  rv = prefBranch->GetCharPref("general.config.vendor", lockVendor);
+  // If vendor is not nullptr, do this check
+  if (NS_SUCCEEDED(rv)) {
+    fileNameLen = strlen(lockFileName.get());
+
+    // lockVendor and lockFileName should be the same with the addtion of
+    // .cfg to the filename by checking this post reading of the cfg file
+    // this value can be set within the cfg file adding a level of security.
+
+    if (strncmp(lockFileName.get(), lockVendor.get(), fileNameLen - 4) != 0) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  // get the value of the autoconfig url
+  nsAutoCString urlName;
+  rv = prefBranch->GetCharPref("autoadmin.global_config_url", urlName);
+  if (NS_SUCCEEDED(rv) && !urlName.IsEmpty()) {
+    // Instantiating nsAutoConfig object if the pref is present
+    mAutoConfig = new nsAutoConfig();
+
+    rv = mAutoConfig->Init();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    mAutoConfig->SetConfigURL(urlName.get());
+  }
+
+  return NS_OK;
+}  // ReadConfigFile
+
+nsresult nsReadConfig::openAndEvaluateJSFile(const char* aFileName,
+                                             int32_t obscureValue,
+                                             bool isEncoded, bool isBinDir) {
+  nsresult rv;
+
+  nsCOMPtr<nsIInputStream> inStr;
+  if (isBinDir) {
+    nsCOMPtr<nsIFile> jsFile;
+#if defined(MOZ_WIDGET_GTK)
+    if (!mozilla::widget::IsRunningUnderFlatpakOrSnap()) {
+#endif  // defined(MOZ_WIDGET_GTK)
+      rv = NS_GetSpecialDirectory(NS_GRE_DIR, getter_AddRefs(jsFile));
+#if defined(MOZ_WIDGET_GTK)
+    } else {
+      rv = NS_GetSpecialDirectory(NS_OS_SYSTEM_CONFIG_DIR,
+                                  getter_AddRefs(jsFile));
+    }
+#endif  // defined(MOZ_WIDGET_GTK)
+    if (NS_FAILED(rv)) return rv;
+
+    rv = jsFile->AppendNative(nsDependentCString(aFileName));
+    if (NS_FAILED(rv)) return rv;
+
+    rv = NS_NewLocalFileInputStream(getter_AddRefs(inStr), jsFile);
+    if (NS_FAILED(rv)) return rv;
+
+  } else {
+    nsAutoCString location("resource://gre/defaults/autoconfig/");
+    location += aFileName;
+
+    nsCOMPtr<nsIURI> uri;
+    rv = NS_NewURI(getter_AddRefs(uri), location);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    nsCOMPtr<nsIChannel> channel;
+    rv = NS_NewChannel(getter_AddRefs(channel), uri,
+                       nsContentUtils::GetSystemPrincipal(),
+                       nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+                       nsIContentPolicy::TYPE_OTHER);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = channel->Open(getter_AddRefs(inStr));
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  uint64_t fs64;
+  uint32_t amt = 0;
+  rv = inStr->Available(&fs64);
+  if (NS_FAILED(rv)) return rv;
+  // This used to use PR_Malloc(), which doesn't support over 4GB.
+  if (fs64 > UINT32_MAX) return NS_ERROR_FILE_TOO_BIG;
+  uint32_t fs = (uint32_t)fs64;
+
+  char* buf = (char*)malloc(fs * sizeof(char));
+  if (!buf) return NS_ERROR_OUT_OF_MEMORY;
+
+  rv = inStr->Read(buf, (uint32_t)fs, &amt);
+  NS_ASSERTION((amt == fs), "failed to read the entire configuration file!!");
+  if (NS_SUCCEEDED(rv)) {
+    if (obscureValue > 0) {
+      // Unobscure file by subtracting some value from every char.
+      for (uint32_t i = 0; i < amt; i++) buf[i] -= obscureValue;
+    }
+    rv = EvaluateAdminConfigScript(buf, amt, aFileName, false, true, isEncoded,
+                                   !isBinDir);
+  }
+  inStr->Close();
+  free(buf);
+
+  return rv;
+}
diff --git a/extensions/pref/autoconfig/src/nsReadConfig.h b/extensions/pref/autoconfig/src/nsReadConfig.h
new file mode 100644
index 0000000000..465a517186
--- /dev/null
+++ b/extensions/pref/autoconfig/src/nsReadConfig.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef nsReadConfig_h
+#define nsReadConfig_h
+
+#include "mozilla/RefPtr.h"
+#include "nsAutoConfig.h"
+#include "nsIObserver.h"
+
+class nsReadConfig final : public nsIObserver {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  nsReadConfig();
+
+  nsresult Init();
+
+ protected:
+  virtual ~nsReadConfig();
+
+  nsresult readConfigFile();
+  nsresult openAndEvaluateJSFile(const char* aFileName, int32_t obscureValue,
+                                 bool isEncoded, bool isBinDir);
+  bool mRead;
+
+ private:
+  RefPtr<nsAutoConfig> mAutoConfig;
+};
+
+#endif
diff --git a/extensions/pref/autoconfig/src/prefcalls.js b/extensions/pref/autoconfig/src/prefcalls.js
new file mode 100644
index 0000000000..b66e5df898
--- /dev/null
+++ b/extensions/pref/autoconfig/src/prefcalls.js
@@ -0,0 +1,225 @@
+/* global processLDAPValues */
+/* -*- tab-width: 4; indent-tabs-mode: nil; js-indent-level: 4 -*-
+ * 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/. */
+
+/* globals gSandbox */
+
+const LDAPSyncQueryContractID = "@mozilla.org/ldapsyncquery;1";
+
+var gVersion;
+var gIsUTF8;
+
+function getPrefBranch() {
+  return Services.prefs.getBranch(null);
+}
+
+function pref(prefName, value) {
+  try {
+    var prefBranch = getPrefBranch();
+
+    if (typeof value == "string") {
+      if (gIsUTF8) {
+        prefBranch.setStringPref(prefName, value);
+        return;
+      }
+      prefBranch.setCharPref(prefName, value);
+    } else if (typeof value == "number") {
+      prefBranch.setIntPref(prefName, value);
+    } else if (typeof value == "boolean") {
+      prefBranch.setBoolPref(prefName, value);
+    }
+  } catch (e) {
+    displayError("pref", e);
+  }
+}
+
+function defaultPref(prefName, value) {
+  try {
+    var prefBranch = Services.prefs.getDefaultBranch(null);
+    if (typeof value == "string") {
+      if (gIsUTF8) {
+        prefBranch.setStringPref(prefName, value);
+        return;
+      }
+      prefBranch.setCharPref(prefName, value);
+    } else if (typeof value == "number") {
+      prefBranch.setIntPref(prefName, value);
+    } else if (typeof value == "boolean") {
+      prefBranch.setBoolPref(prefName, value);
+    }
+  } catch (e) {
+    displayError("defaultPref", e);
+  }
+}
+
+function lockPref(prefName, value) {
+  try {
+    var prefBranch = getPrefBranch();
+
+    if (prefBranch.prefIsLocked(prefName)) {
+      prefBranch.unlockPref(prefName);
+    }
+
+    defaultPref(prefName, value);
+
+    prefBranch.lockPref(prefName);
+  } catch (e) {
+    displayError("lockPref", e);
+  }
+}
+
+function unlockPref(prefName) {
+  try {
+    var prefBranch = getPrefBranch();
+    prefBranch.unlockPref(prefName);
+  } catch (e) {
+    displayError("unlockPref", e);
+  }
+}
+
+function getPref(prefName) {
+  try {
+    var prefBranch = getPrefBranch();
+
+    switch (prefBranch.getPrefType(prefName)) {
+      case prefBranch.PREF_STRING:
+        if (gIsUTF8) {
+          return prefBranch.getStringPref(prefName);
+        }
+        return prefBranch.getCharPref(prefName);
+
+      case prefBranch.PREF_INT:
+        return prefBranch.getIntPref(prefName);
+
+      case prefBranch.PREF_BOOL:
+        return prefBranch.getBoolPref(prefName);
+      default:
+        return null;
+    }
+  } catch (e) {
+    displayError("getPref", e);
+  }
+  return undefined;
+}
+
+function clearPref(prefName) {
+  try {
+    var prefBranch = getPrefBranch();
+    prefBranch.clearUserPref(prefName);
+  } catch (e) {}
+}
+
+function setLDAPVersion(version) {
+  gVersion = version;
+}
+
+function getLDAPAttributes(host, base, filter, attribs, isSecure) {
+  try {
+    var urlSpec =
+      "ldap" +
+      (isSecure ? "s" : "") +
+      "://" +
+      host +
+      (isSecure ? ":636" : "") +
+      "/" +
+      base +
+      "?" +
+      attribs +
+      "?sub?" +
+      filter;
+
+    // nsILDAP* are only defined in comm-central.
+    // eslint-disable-next-line mozilla/valid-ci-uses
+    var url = Services.io.newURI(urlSpec).QueryInterface(Ci.nsILDAPURL);
+
+    var ldapquery = Cc[LDAPSyncQueryContractID].createInstance(
+      // eslint-disable-next-line mozilla/valid-ci-uses
+      Ci.nsILDAPSyncQuery
+    );
+    // default to LDAP v3
+    if (!gVersion) {
+      // eslint-disable-next-line mozilla/valid-ci-uses
+      gVersion = Ci.nsILDAPConnection.VERSION3;
+    }
+    // user supplied method
+    if ("processLDAPValues" in gSandbox) {
+      gSandbox.processLDAPValues(ldapquery.getQueryResults(url, gVersion));
+    } else {
+      processLDAPValues(ldapquery.getQueryResults(url, gVersion));
+    }
+  } catch (e) {
+    displayError("getLDAPAttributes", e);
+  }
+}
+
+function getLDAPValue(str, key) {
+  try {
+    if (str == null || key == null) {
+      return null;
+    }
+
+    var search_key = "\n" + key + "=";
+
+    var start_pos = str.indexOf(search_key);
+    if (start_pos == -1) {
+      return null;
+    }
+
+    start_pos += search_key.length;
+
+    var end_pos = str.indexOf("\n", start_pos);
+    if (end_pos == -1) {
+      end_pos = str.length;
+    }
+
+    return str.substring(start_pos, end_pos);
+  } catch (e) {
+    displayError("getLDAPValue", e);
+  }
+  return undefined;
+}
+
+function displayError(funcname, message) {
+  try {
+    var bundle = Services.strings.createBundle(
+      "chrome://autoconfig/locale/autoconfig.properties"
+    );
+
+    var title = bundle.GetStringFromName("autoConfigTitle");
+    var msg = bundle.formatStringFromName("autoConfigMsg", [funcname]);
+    Services.prompt.alert(null, title, msg + " " + message);
+  } catch (e) {}
+}
+
+function getenv(name) {
+  try {
+    return Services.env.get(name);
+  } catch (e) {
+    displayError("getEnvironment", e);
+  }
+  return undefined;
+}
+
+var APIs = {
+  pref,
+  defaultPref,
+  lockPref,
+  unlockPref,
+  getPref,
+  clearPref,
+  setLDAPVersion,
+  getLDAPAttributes,
+  getLDAPValue,
+  displayError,
+  getenv,
+};
+
+for (let [defineAs, func] of Object.entries(APIs)) {
+  Cu.exportFunction(func, gSandbox, { defineAs });
+}
+
+Object.defineProperty(Cu.waiveXrays(gSandbox), "gIsUTF8", {
+  get: Cu.exportFunction(() => gIsUTF8, gSandbox),
+});
diff --git a/extensions/pref/autoconfig/test/marionette/autoconfig.cfg b/extensions/pref/autoconfig/test/marionette/autoconfig.cfg
new file mode 100644
index 0000000000..1e6fde18bf
--- /dev/null
+++ b/extensions/pref/autoconfig/test/marionette/autoconfig.cfg
@@ -0,0 +1,18 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+
+// Verify this one has a user value
+pref("_autoconfig_.test.userpref", "userpref");
+
+// Verify this one has a default pref
+defaultPref("_autoconfig_.test.defaultpref", "defaultpref");
+
+// Verify this one is locked
+lockPref("_autoconfig_.test.lockpref", "lockpref");
+
+lockPref("_autoconfig_.test.unlockpref", "unlockpref");
+// Verify this one is unlocked
+unlockPref("_autoconfig_.test.unlockpref");
+
+pref("_autoconfig_.test.clearpref", "clearpref");
+// Verify this one has no value
+clearPref("_autoconfig_.test.clearpref");
diff --git a/extensions/pref/autoconfig/test/marionette/autoconfig.js b/extensions/pref/autoconfig/test/marionette/autoconfig.js
new file mode 100644
index 0000000000..c891c5d108
--- /dev/null
+++ b/extensions/pref/autoconfig/test/marionette/autoconfig.js
@@ -0,0 +1,5 @@
+/* global pref */
+pref("general.config.sandbox_enabled", true);
+pref("general.config.filename", "autoconfig.cfg");
+pref("general.config.vendor", "autoconfig");
+pref("general.config.obscure_value", 0);
diff --git a/extensions/pref/autoconfig/test/marionette/manifest.ini b/extensions/pref/autoconfig/test/marionette/manifest.ini
new file mode 100644
index 0000000000..c10c20c2ae
--- /dev/null
+++ b/extensions/pref/autoconfig/test/marionette/manifest.ini
@@ -0,0 +1 @@
+[test_autoconfig.py]

diff --git a/extensions/pref/autoconfig/test/marionette/test_autoconfig.py b/extensions/pref/autoconfig/test/marionette/test_autoconfig.py
new file mode 100644
index 0000000000..0cdc0feede
--- /dev/null
+++ b/extensions/pref/autoconfig/test/marionette/test_autoconfig.py
@@ -0,0 +1,101 @@
+# 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/.
+
+import os
+import shutil
+
+from marionette_harness import MarionetteTestCase
+
+
+class TestAutoConfig(MarionetteTestCase):
+    def tearDown(self):
+        self.marionette.quit(in_app=False, clean=True)
+
+        if hasattr(self, "pref_file"):
+            os.remove(self.pref_file)
+        if hasattr(self, "autoconfig_file"):
+            os.remove(self.autoconfig_file)
+
+        super(TestAutoConfig, self).tearDown()
+
+    def pref_has_user_value(self, pref):
+        with self.marionette.using_context("chrome"):
+            return self.marionette.execute_script(
+                """
+                return Services.prefs.prefHasUserValue(arguments[0]);
+                """,
+                script_args=(pref,),
+            )
+
+    def pref_is_locked(self, pref):
+        with self.marionette.using_context("chrome"):
+            return self.marionette.execute_script(
+                """
+                return Services.prefs.prefIsLocked(arguments[0]);
+                """,
+                script_args=(pref,),
+            )
+
+    def test_autoconfig(self):
+        with self.marionette.using_context("chrome"):
+            self.exe_dir = self.marionette.execute_script(
+                """
+              return Services.dirsvc.get("GreD", Ci.nsIFile).path;
+            """
+            )
+
+        self.marionette.quit()
+
+        test_dir = os.path.dirname(__file__)
+        self.pref_file = os.path.join(self.exe_dir, "defaults", "pref", "autoconfig.js")
+        shutil.copyfile(os.path.join(test_dir, "autoconfig.js"), self.pref_file)
+        self.autoconfig_file = os.path.join(self.exe_dir, "autoconfig.cfg")
+        shutil.copyfile(os.path.join(test_dir, "autoconfig.cfg"), self.autoconfig_file)
+
+        self.marionette.start_session()
+
+        with self.marionette.using_context("chrome"):
+            self.assertTrue(
+                self.pref_has_user_value("_autoconfig_.test.userpref"),
+                "Pref should have user value",
+            )
+
+            self.assertEqual(
+                self.marionette.get_pref("_autoconfig_.test.userpref"),
+                "userpref",
+                "User pref should be set",
+            )
+
+            self.assertEqual(
+                self.marionette.get_pref("_autoconfig_.test.defaultpref", True),
+                "defaultpref",
+                "Default pref should be set",
+            )
+
+            self.assertTrue(
+                self.pref_is_locked("_autoconfig_.test.lockpref"),
+                "Pref should be locked",
+            )
+
+            self.assertEqual(
+                self.marionette.get_pref("_autoconfig_.test.lockpref"),
+                "lockpref",
+                "Locked pref should be set",
+            )
+
+            self.assertFalse(
+                self.pref_is_locked("_autoconfig_.test.unlockpref"),
+                "Pref should be unlocked",
+            )
+
+            self.assertEqual(
+                self.marionette.get_pref("_autoconfig_.test.unlockpref"),
+                "unlockpref",
+                "Unlocked pref should be set",
+            )
+
+            self.assertFalse(
+                self.pref_has_user_value("_autoconfig_.test.clearpref"),
+                "Pref should be cleared",
+            )
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-all.cfg b/extensions/pref/autoconfig/test/unit/autoconfig-all.cfg
new file mode 100644
index 0000000000..f636c3ec22
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-all.cfg
@@ -0,0 +1,31 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+
+// Verify this one has a user value
+pref("_autoconfig_.test.userpref", "userpref");
+
+// Verify this one has a default pref
+defaultPref("_autoconfig_.test.defaultpref", "defaultpref");
+
+// Verify this one is locked
+lockPref("_autoconfig_.test.lockpref", "lockpref");
+
+lockPref("_autoconfig_.test.unlockpref", "unlockpref");
+// Verify this one is unlocked
+unlockPref("_autoconfig_.test.unlockpref");
+
+pref("_autoconfig_.test.clearpref", "clearpref");
+// Verify this one has no value
+clearPref("_autoconfig_.test.clearpref");
+
+// Verify this one is set to the correct value
+pref("_autoconfig_.test.getpref.query", "getpref");
+pref("_autoconfig_.test.getpref", getPref("_autoconfig_.test.getpref.query"));
+
+// Verify this one is set to the correct value
+pref("_autoconfig_.test.getenv", getenv("AUTOCONFIG_TEST_GETENV"));
+
+// Since we can't test displayError directly, verify that it
+// exists and is a function
+pref("_autoconfig_.test.displayerror", typeof(displayError));
+
+// We are not getPrefBranch because it is being removed
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-chromecheck.cfg b/extensions/pref/autoconfig/test/unit/autoconfig-chromecheck.cfg
new file mode 100644
index 0000000000..2af6cfc109
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-chromecheck.cfg
@@ -0,0 +1,5 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+
+lockPref("_test.string.typeofComponents", typeof Components);
+lockPref("_test.string.typeofChromeUtils", typeof ChromeUtils);
+lockPref("_test.string.typeofServices", typeof Services);
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-latin1.cfg b/extensions/pref/autoconfig/test/unit/autoconfig-latin1.cfg
new file mode 100644
index 0000000000..6b96c65fd0
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-latin1.cfg
@@ -0,0 +1,6 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+// ©
+lockPref("_test.string.ASCII", "ASCII");
+lockPref("_test.string.non-ASCII", "日本語");
+lockPref("_test.string.getPref", getPref("_test.string.non-ASCII"));
+lockPref("_test.string.gIsUTF8", String(this.gIsUTF8));
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-no-sandbox-check.cfg b/extensions/pref/autoconfig/test/unit/autoconfig-no-sandbox-check.cfg
new file mode 100644
index 0000000000..a39080562f
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-no-sandbox-check.cfg
@@ -0,0 +1,5 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+
+lockPref("_test.typeof_Components", typeof Components);
+lockPref("_test.typeof_ChromeUtils", typeof ChromeUtils);
+lockPref("_test.typeof_Services", typeof Services);
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-no-sandbox.js b/extensions/pref/autoconfig/test/unit/autoconfig-no-sandbox.js
new file mode 100644
index 0000000000..a53b53dfb6
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-no-sandbox.js
@@ -0,0 +1,5 @@
+/* global pref */
+pref("general.config.sandbox_enabled", false);
+pref("general.config.filename", "autoconfig.cfg");
+pref("general.config.vendor", "autoconfig");
+pref("general.config.obscure_value", 0);
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-snap.cfg b/extensions/pref/autoconfig/test/unit/autoconfig-snap.cfg
new file mode 100644
index 0000000000..c5c67bfbb7
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-snap.cfg
@@ -0,0 +1,4 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+
+// Verify this one has a user value
+pref("_autoconfig_.test.userpref-snap", "userpref-snap");
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig-utf8.cfg b/extensions/pref/autoconfig/test/unit/autoconfig-utf8.cfg
new file mode 100644
index 0000000000..eec7899420
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig-utf8.cfg
@@ -0,0 +1,6 @@
+// # don't remove this comment! (the first line is ignored by Mozilla)
+
+lockPref("_test.string.ASCII", "UTF-8");
+lockPref("_test.string.non-ASCII", "日本語");
+lockPref("_test.string.getPref", getPref("_test.string.non-ASCII"));
+lockPref("_test.string.gIsUTF8", String(this.gIsUTF8));
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig.js b/extensions/pref/autoconfig/test/unit/autoconfig.js
new file mode 100644
index 0000000000..c891c5d108
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig.js
@@ -0,0 +1,5 @@
+/* global pref */
+pref("general.config.sandbox_enabled", true);
+pref("general.config.filename", "autoconfig.cfg");
+pref("general.config.vendor", "autoconfig");
+pref("general.config.obscure_value", 0);
diff --git a/extensions/pref/autoconfig/test/unit/autoconfig_snap.js b/extensions/pref/autoconfig/test/unit/autoconfig_snap.js
new file mode 100644
index 0000000000..bfa1df4859
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/autoconfig_snap.js
@@ -0,0 +1,5 @@
+/* global pref */
+pref("general.config.sandbox_enabled", true);
+pref("general.config.filename", "autoconfig-snap.cfg");
+pref("general.config.vendor", "autoconfig-snap");
+pref("general.config.obscure_value", 0);
diff --git a/extensions/pref/autoconfig/test/unit/test_autoconfig.js b/extensions/pref/autoconfig/test/unit/test_autoconfig.js
new file mode 100644
index 0000000000..60284c4544
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/test_autoconfig.js
@@ -0,0 +1,83 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint no-unsafe-finally: "off"*/
+/* Turning off this rule to allow control flow operations in finally block
+ * http://eslint.org/docs/rules/no-unsafe-finally  */
+
+function run_test() {
+  let prefs = Services.prefs.getBranch(null);
+  let defPrefs = Services.prefs.getDefaultBranch(null);
+
+  let greD = Services.dirsvc.get("GreD", Ci.nsIFile);
+  let defaultPrefD = Services.dirsvc.get("PrfDef", Ci.nsIFile);
+  let testDir = do_get_cwd();
+
+  try {
+    let autoConfigJS = testDir.clone();
+    autoConfigJS.append("autoconfig.js");
+    autoConfigJS.copyTo(defaultPrefD, "autoconfig.js");
+
+    // Make sure nsReadConfig is initialized.
+    Cc["@mozilla.org/readconfig;1"].getService(Ci.nsISupports);
+    Services.prefs.resetPrefs();
+
+    let autoConfigCfg = testDir.clone();
+    autoConfigCfg.append("autoconfig-all.cfg");
+    autoConfigCfg.copyTo(greD, "autoconfig.cfg");
+
+    Services.env.set("AUTOCONFIG_TEST_GETENV", "getenv");
+
+    Services.obs.notifyObservers(
+      Services.prefs,
+      "prefservice:before-read-userprefs"
+    );
+
+    ok(prefs.prefHasUserValue("_autoconfig_.test.userpref"));
+    equal("userpref", prefs.getStringPref("_autoconfig_.test.userpref"));
+
+    equal(
+      "defaultpref",
+      defPrefs.getStringPref("_autoconfig_.test.defaultpref")
+    );
+    equal("defaultpref", prefs.getStringPref("_autoconfig_.test.defaultpref"));
+
+    ok(prefs.prefIsLocked("_autoconfig_.test.lockpref"));
+    equal("lockpref", prefs.getStringPref("_autoconfig_.test.lockpref"));
+
+    ok(!prefs.prefIsLocked("_autoconfig_.test.unlockpref"));
+    equal("unlockpref", prefs.getStringPref("_autoconfig_.test.unlockpref"));
+
+    ok(!prefs.prefHasUserValue("_autoconfig_.test.clearpref"));
+
+    equal("getpref", prefs.getStringPref("_autoconfig_.test.getpref"));
+
+    equal("getenv", prefs.getStringPref("_autoconfig_.test.getenv"));
+
+    equal("function", prefs.getStringPref("_autoconfig_.test.displayerror"));
+
+    Services.prefs.resetPrefs();
+  } finally {
+    try {
+      let autoConfigJS = defaultPrefD.clone();
+      autoConfigJS.append("autoconfig.js");
+      autoConfigJS.remove(false);
+    } catch (e) {
+      if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+        throw e;
+      }
+    }
+
+    try {
+      let autoConfigCfg = greD.clone();
+      autoConfigCfg.append("autoconfig.cfg");
+      autoConfigCfg.remove(false);
+    } catch (e) {
+      if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+        throw e;
+      }
+    }
+
+    Services.prefs.resetPrefs();
+  }
+}
diff --git a/extensions/pref/autoconfig/test/unit/test_autoconfig_custom_path.js b/extensions/pref/autoconfig/test/unit/test_autoconfig_custom_path.js
new file mode 100644
index 0000000000..abfa8881b9
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/test_autoconfig_custom_path.js
@@ -0,0 +1,22 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const { updateAppInfo } = ChromeUtils.importESModule(
+  "resource://testing-common/AppInfo.sys.mjs"
+);
+
+function run_test() {
+  let testDirName = do_get_cwd().clone();
+  Services.env.set("MOZ_SYSTEM_CONFIG_DIR", testDirName.path);
+
+  updateAppInfo();
+
+  try {
+    Services.dirsvc.undefine("SysConfD");
+  } catch (e) {}
+  let customSysConfD = Services.dirsvc.get("SysConfD", Ci.nsIFile);
+  let parent = customSysConfD.parent;
+  let child = customSysConfD.leafName;
+  notEqual("/etc", parent.path, "SysConfD is not in /etc");
+  equal("xpcshell", child, "SysConfD is xpcshell");
+}
diff --git a/extensions/pref/autoconfig/test/unit/test_autoconfig_default_path.js b/extensions/pref/autoconfig/test/unit/test_autoconfig_default_path.js
new file mode 100644
index 0000000000..20d3801ab1
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/test_autoconfig_default_path.js
@@ -0,0 +1,16 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const { updateAppInfo } = ChromeUtils.importESModule(
+  "resource://testing-common/AppInfo.sys.mjs"
+);
+
+function run_test() {
+  updateAppInfo();
+
+  try {
+    Services.dirsvc.undefine("SysConfD");
+  } catch (e) {}
+  let defaultSysConfD = Services.dirsvc.get("SysConfD", Ci.nsIFile);
+  equal("/etc/xpcshell", defaultSysConfD.path, "SysConfD is in /etc");
+}
diff --git a/extensions/pref/autoconfig/test/unit/test_autoconfig_no_sandbox.js b/extensions/pref/autoconfig/test/unit/test_autoconfig_no_sandbox.js
new file mode 100644
index 0000000000..7553432bc0
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/test_autoconfig_no_sandbox.js
@@ -0,0 +1,59 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint no-unsafe-finally: "off"*/
+
+function run_test() {
+  let prefs = Services.prefs.getBranch(null);
+
+  let greD = Services.dirsvc.get("GreD", Ci.nsIFile);
+  let defaultPrefD = Services.dirsvc.get("PrfDef", Ci.nsIFile);
+  let testDir = do_get_cwd();
+
+  try {
+    let autoConfigJS = testDir.clone();
+    autoConfigJS.append("autoconfig-no-sandbox.js");
+    autoConfigJS.copyTo(defaultPrefD, "autoconfig.js");
+
+    // Make sure nsReadConfig is initialized.
+    Cc["@mozilla.org/readconfig;1"].getService(Ci.nsISupports);
+    Services.prefs.resetPrefs();
+
+    let autoConfigCfg = testDir.clone();
+    autoConfigCfg.append("autoconfig-no-sandbox-check.cfg");
+    autoConfigCfg.copyTo(greD, "autoconfig.cfg");
+
+    Services.obs.notifyObservers(
+      Services.prefs,
+      "prefservice:before-read-userprefs"
+    );
+
+    equal("object", prefs.getStringPref("_test.typeof_Components"));
+    equal("object", prefs.getStringPref("_test.typeof_ChromeUtils"));
+    equal("object", prefs.getStringPref("_test.typeof_Services"));
+
+    Services.prefs.resetPrefs();
+  } finally {
+    try {
+      let autoConfigJS = defaultPrefD.clone();
+      autoConfigJS.append("autoconfig.js");
+      autoConfigJS.remove(false);
+    } catch (e) {
+      if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+        throw e;
+      }
+    }
+
+    try {
+      let autoConfigCfg = greD.clone();
+      autoConfigCfg.append("autoconfig.cfg");
+      autoConfigCfg.remove(false);
+    } catch (e) {
+      if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+        throw e;
+      }
+    }
+
+    Services.prefs.resetPrefs();
+  }
+}
diff --git a/extensions/pref/autoconfig/test/unit/test_autoconfig_nonascii.js b/extensions/pref/autoconfig/test/unit/test_autoconfig_nonascii.js
new file mode 100644
index 0000000000..e535469360
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/test_autoconfig_nonascii.js
@@ -0,0 +1,110 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint no-unsafe-finally: "off"*/
+/* Turning off this rule to allow control flow operations in finally block
+ * http://eslint.org/docs/rules/no-unsafe-finally  */
+
+function run_test() {
+  let greD = Services.dirsvc.get("GreD", Ci.nsIFile);
+  let defaultPrefD = Services.dirsvc.get("PrfDef", Ci.nsIFile);
+  let testDir = do_get_cwd();
+
+  try {
+    let autoConfigJS = testDir.clone();
+    autoConfigJS.append("autoconfig.js");
+    autoConfigJS.copyTo(defaultPrefD, "autoconfig.js");
+
+    // Make sure nsReadConfig is initialized.
+    Cc["@mozilla.org/readconfig;1"].getService(Ci.nsISupports);
+    Services.prefs.resetPrefs();
+
+    var tests = [
+      {
+        filename: "autoconfig-utf8.cfg",
+        prefs: {
+          "_test.string.ASCII": "UTF-8",
+          "_test.string.non-ASCII": "日本語",
+          "_test.string.getPref": "日本語",
+          "_test.string.gIsUTF8": "true",
+        },
+      },
+      {
+        filename: "autoconfig-latin1.cfg",
+        prefs: {
+          "_test.string.ASCII": "ASCII",
+          "_test.string.non-ASCII": "日本語",
+          "_test.string.getPref": "日本語",
+          "_test.string.gIsUTF8": "false",
+        },
+      },
+      {
+        filename: "autoconfig-chromecheck.cfg",
+        prefs: {
+          "_test.string.typeofComponents": "undefined",
+          "_test.string.typeofChromeUtils": "undefined",
+          "_test.string.typeofServices": "undefined",
+        },
+      },
+    ];
+
+    function testAutoConfig(test) {
+      // Make sure pref values are unset.
+      for (let prefName in test.prefs) {
+        Assert.equal(
+          Ci.nsIPrefBranch.PREF_INVALID,
+          Services.prefs.getPrefType(prefName)
+        );
+      }
+
+      let autoConfigCfg = testDir.clone();
+      autoConfigCfg.append(test.filename);
+      autoConfigCfg.copyTo(greD, "autoconfig.cfg");
+
+      Services.obs.notifyObservers(
+        Services.prefs,
+        "prefservice:before-read-userprefs"
+      );
+
+      for (let prefName in test.prefs) {
+        Assert.equal(
+          test.prefs[prefName],
+          Services.prefs.getStringPref(prefName)
+        );
+      }
+
+      Services.prefs.resetPrefs();
+      // Make sure pref values are reset.
+      for (let prefName in test.prefs) {
+        Assert.equal(
+          Ci.nsIPrefBranch.PREF_INVALID,
+          Services.prefs.getPrefType(prefName)
+        );
+      }
+    }
+
+    tests.forEach(testAutoConfig);
+  } finally {
+    try {
+      let autoConfigJS = defaultPrefD.clone();
+      autoConfigJS.append("autoconfig.js");
+      autoConfigJS.remove(false);
+    } catch (e) {
+      if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+        throw e;
+      }
+    }
+
+    try {
+      let autoConfigCfg = greD.clone();
+      autoConfigCfg.append("autoconfig.cfg");
+      autoConfigCfg.remove(false);
+    } catch (e) {
+      if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+        throw e;
+      }
+    }
+
+    Services.prefs.resetPrefs();
+  }
+}
diff --git a/extensions/pref/autoconfig/test/unit/test_autoconfig_snap.js b/extensions/pref/autoconfig/test/unit/test_autoconfig_snap.js
new file mode 100644
index 0000000000..1a58e11cf5
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/test_autoconfig_snap.js
@@ -0,0 +1,77 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/* eslint no-unsafe-finally: "off"*/
+/* Turning off this rule to allow control flow operations in finally block
+ * http://eslint.org/docs/rules/no-unsafe-finally  */
+
+const { updateAppInfo } = ChromeUtils.importESModule(
+  "resource://testing-common/AppInfo.sys.mjs"
+);
+
+function ensureRemove(file) {
+  try {
+    file.remove(false);
+  } catch (e) {
+    if (e.result != Cr.NS_ERROR_FILE_NOT_FOUND) {
+      throw e;
+    }
+  }
+}
+
+async function run_test() {
+  let prefs = Services.prefs.getBranch(null);
+
+  let testDir = do_get_cwd();
+  let confDir = testDir.clone();
+  confDir.append("MozSystemConfigDir");
+  Services.env.set("MOZ_SYSTEM_CONFIG_DIR", confDir.path);
+  Services.env.set("SNAP_INSTANCE_NAME", "xpcshell");
+
+  updateAppInfo();
+
+  let sysConfD = Services.dirsvc.get("SysConfD", Ci.nsIFile);
+
+  let defaultPrefDExtra = sysConfD.clone();
+  defaultPrefDExtra.append("defaults");
+  defaultPrefDExtra.append("pref");
+
+  await IOUtils.makeDirectory(defaultPrefDExtra.path);
+
+  const kAutoConfigFile = defaultPrefDExtra.clone();
+  kAutoConfigFile.append("autoconfig_snap.js");
+  const kAutoConfigCfg = sysConfD.clone();
+  kAutoConfigCfg.append("autoconfig-snap.cfg");
+
+  let autoConfigJS = testDir.clone();
+  autoConfigJS.append(kAutoConfigFile.leafName);
+
+  let autoConfigCfg = testDir.clone();
+  autoConfigCfg.append(kAutoConfigCfg.leafName);
+
+  try {
+    autoConfigJS.copyTo(kAutoConfigFile.parent, kAutoConfigFile.leafName);
+    autoConfigCfg.copyTo(kAutoConfigCfg.parent, kAutoConfigCfg.leafName);
+
+    // Make sure nsReadConfig is initialized.
+    Cc["@mozilla.org/readconfig;1"].getService(Ci.nsISupports);
+    Services.prefs.resetPrefs();
+
+    Services.obs.notifyObservers(
+      Services.prefs,
+      "prefservice:before-read-userprefs"
+    );
+
+    ok(prefs.prefHasUserValue("_autoconfig_.test.userpref-snap"));
+    equal(
+      "userpref-snap",
+      prefs.getStringPref("_autoconfig_.test.userpref-snap")
+    );
+
+    Services.prefs.resetPrefs();
+  } finally {
+    ensureRemove(kAutoConfigFile);
+    ensureRemove(kAutoConfigCfg);
+    Services.prefs.resetPrefs();
+  }
+}
diff --git a/extensions/pref/autoconfig/test/unit/xpcshell.ini b/extensions/pref/autoconfig/test/unit/xpcshell.ini
new file mode 100644
index 0000000000..fd09da01af
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/xpcshell.ini
@@ -0,0 +1,23 @@
+[DEFAULT]
+head =
+skip-if =
+  toolkit == 'android'
+  os == 'win' && msix # Does not work in MSIX builds.
+support-files =
+  autoconfig-all.cfg
+  autoconfig-latin1.cfg
+  autoconfig-utf8.cfg
+  autoconfig-chromecheck.cfg
+  autoconfig-no-sandbox-check.cfg
+  autoconfig.js
+  autoconfig-no-sandbox.js
+
+[test_autoconfig.js]
+[test_autoconfig_nonascii.js]
+run-sequentially = very high failure rate in parallel
+[test_autoconfig_no_sandbox.js]
+run-sequentially = very high failure rate in parallel
+[test_autoconfig_default_path.js]
+run-if = os == 'linux'
+[test_autoconfig_custom_path.js]
+run-if = os == 'linux'
diff --git a/extensions/pref/autoconfig/test/unit/xpcshell_snap.ini b/extensions/pref/autoconfig/test/unit/xpcshell_snap.ini
new file mode 100644
index 0000000000..ff24d46646
--- /dev/null
+++ b/extensions/pref/autoconfig/test/unit/xpcshell_snap.ini
@@ -0,0 +1,8 @@
+[DEFAULT]
+head =
+skip-if = os != 'linux'
+
+[test_autoconfig_snap.js]
+support-files =
+  autoconfig_snap.js
+  autoconfig-snap.cfg
diff --git a/extensions/pref/moz.build b/extensions/pref/moz.build
new file mode 100644
index 0000000000..b0b3670440
--- /dev/null
+++ b/extensions/pref/moz.build
@@ -0,0 +1,11 @@
+# -*- 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/.
+
+
+DIRS += ["autoconfig"]
+
+with Files("**"):
+    BUG_COMPONENT = ("Core", "AutoConfig (Mission Control Desktop)")