From 1e16e5eee8c76a79cc79099fed5c7b4bf663448d Mon Sep 17 00:00:00 2001
From: John Blackbourn <johnbillion@git.wordpress.org>
Date: Mon, 2 Oct 2017 23:20:12 +0000
Subject: [PATCH] I18N: Allow the login screen language to be specified via a
 `wp_lang` query variable, and use this for the interim login modal.

This allows users who are using the admin area in a language other than the site language to read the notice on the login screen
(which explains that they need to log in again) in their chosen language.

Props Nikschavan, swissspidy

Fixes #40205


git-svn-id: https://develop.svn.wordpress.org/trunk@41692 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/functions.php |  6 +++++-
 src/wp-login.php              | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 01d8a88bb4..c00e34da9d 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -5342,8 +5342,12 @@ function wp_auth_check_html() {
 	<?php
 
 	if ( $same_domain ) {
+		$login_src = add_query_arg( array(
+			'interim-login' => '1',
+			'wp_lang'       => get_user_locale(),
+		), $login_url );
 		?>
-		<div id="wp-auth-check-form" class="loading" data-src="<?php echo esc_url( add_query_arg( array( 'interim-login' => 1 ), $login_url ) ); ?>"></div>
+		<div id="wp-auth-check-form" class="loading" data-src="<?php echo esc_url( $login_src ); ?>"></div>
 		<?php
 	}
 
diff --git a/src/wp-login.php b/src/wp-login.php
index 869502414b..4ae5f161a6 100644
--- a/src/wp-login.php
+++ b/src/wp-login.php
@@ -425,12 +425,16 @@ setcookie( TEST_COOKIE, 'WP Cookie check', 0, COOKIEPATH, COOKIE_DOMAIN, $secure
 if ( SITECOOKIEPATH != COOKIEPATH )
 	setcookie( TEST_COOKIE, 'WP Cookie check', 0, SITECOOKIEPATH, COOKIE_DOMAIN, $secure );
 
+$lang            = ! empty( $_GET['wp_lang'] ) ? sanitize_text_field( $_GET['wp_lang'] ) : '';
+$switched_locale = switch_to_locale( $lang );
+
 /**
  * Fires when the login form is initialized.
  *
  * @since 3.2.0
  */
 do_action( 'login_init' );
+
 /**
  * Fires before a specified login form action.
  *
@@ -484,6 +488,10 @@ case 'postpass' :
 	}
 	setcookie( 'wp-postpass_' . COOKIEHASH, $hasher->HashPassword( wp_unslash( $_POST['post_password'] ) ), $expire, COOKIEPATH, COOKIE_DOMAIN, $secure );
 
+	if ( $switched_locale ) {
+	    restore_previous_locale();
+	}
+
 	wp_safe_redirect( wp_get_referer() );
 	exit();
 
@@ -501,6 +509,10 @@ case 'logout' :
 		$requested_redirect_to = '';
 	}
 
+	if ( $switched_locale ) {
+	    restore_previous_locale();
+	}
+
 	/**
 	 * Filters the log out redirect URL.
 	 *
@@ -589,6 +601,11 @@ endif;
 
 <?php
 login_footer('user_login');
+
+if ( $switched_locale ) {
+    restore_previous_locale();
+}
+
 break;
 
 case 'resetpass' :
@@ -713,6 +730,11 @@ endif;
 
 <?php
 login_footer('user_pass');
+
+if ( $switched_locale ) {
+    restore_previous_locale();
+}
+
 break;
 
 case 'register' :
@@ -788,6 +810,11 @@ case 'register' :
 
 <?php
 login_footer('user_login');
+
+if ( $switched_locale ) {
+    restore_previous_locale();
+}
+
 break;
 
 case 'login' :
@@ -1031,5 +1058,10 @@ try {
 
 <?php
 login_footer();
+
+if ( $switched_locale ) {
+    restore_previous_locale();
+}
+
 break;
 } // end action switch