From c117fbe0cfadfdddd8ca579ad78dc7cb405e2859 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Sat, 25 Apr 2020 20:18:00 +0000
Subject: [PATCH] Upgrade/Install: Introduce `wp_in_maintenance_mode()`, a
 helper function to check if WordPress is currently in maintenance mode.

Props Clorith.
Fixes #49959.

git-svn-id: https://develop.svn.wordpress.org/trunk@47623 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/load.php | 82 ++++++++++++++++++++++++----------------
 1 file changed, 49 insertions(+), 33 deletions(-)

diff --git a/src/wp-includes/load.php b/src/wp-includes/load.php
index 897f5842e1..72d92e58e7 100644
--- a/src/wp-includes/load.php
+++ b/src/wp-includes/load.php
@@ -146,46 +146,15 @@ function wp_favicon_request() {
 /**
  * Die with a maintenance message when conditions are met.
  *
- * Checks for a file in the WordPress root directory named ".maintenance".
- * This file will contain the variable $upgrading, set to the time the file
- * was created. If the file was created less than 10 minutes ago, WordPress
- * enters maintenance mode and displays a message.
- *
  * The default message can be replaced by using a drop-in (maintenance.php in
  * the wp-content directory).
  *
  * @since 3.0.0
  * @access private
- *
- * @global int $upgrading the unix timestamp marking when upgrading WordPress began.
  */
 function wp_maintenance() {
-	if ( ! file_exists( ABSPATH . '.maintenance' ) || wp_installing() ) {
-		return;
-	}
-
-	global $upgrading;
-
-	require ABSPATH . '.maintenance';
-	// If the $upgrading timestamp is older than 10 minutes, don't die.
-	if ( ( time() - $upgrading ) >= 600 ) {
-		return;
-	}
-
-	/**
-	 * Filters whether to enable maintenance mode.
-	 *
-	 * This filter runs before it can be used by plugins. It is designed for
-	 * non-web runtimes. If this filter returns true, maintenance mode will be
-	 * active and the request will end. If false, the request will be allowed to
-	 * continue processing even if maintenance mode should be active.
-	 *
-	 * @since 4.6.0
-	 *
-	 * @param bool $enable_checks Whether to enable maintenance mode. Default true.
-	 * @param int  $upgrading     The timestamp set in the .maintenance file.
-	 */
-	if ( ! apply_filters( 'enable_maintenance_mode', true, $upgrading ) ) {
+	// Return if maintenance mode is disabled.
+	if ( ! wp_in_maintenance_mode() ) {
 		return;
 	}
 
@@ -206,6 +175,53 @@ function wp_maintenance() {
 	);
 }
 
+/**
+ * Check if maintenance mode is enabled.
+ *
+ * Checks for a file in the WordPress root directory named ".maintenance".
+ * This file will contain the variable $upgrading, set to the time the file
+ * was created. If the file was created less than 10 minutes ago, WordPress
+ * is in maintenance mode.
+ *
+ * @since 5.5.0
+ *
+ * @global int $upgrading The Unix timestamp marking when upgrading WordPress began.
+ *
+ * @return bool True if maintenance mode is enabled, false otherwise.
+ */
+function wp_in_maintenance_mode() {
+	global $upgrading;
+
+	if ( ! file_exists( ABSPATH . '.maintenance' ) || wp_installing() ) {
+		return false;
+	}
+
+	require ABSPATH . '.maintenance';
+	// If the $upgrading timestamp is older than 10 minutes, consider maintenance over.
+	if ( ( time() - $upgrading ) >= 600 ) {
+		return false;
+	}
+
+	/**
+	 * Filters whether to enable maintenance mode.
+	 *
+	 * This filter runs before it can be used by plugins. It is designed for
+	 * non-web runtimes. If this filter returns true, maintenance mode will be
+	 * active and the request will end. If false, the request will be allowed to
+	 * continue processing even if maintenance mode should be active.
+	 *
+	 * @since 4.6.0
+	 *
+	 * @param bool $enable_checks Whether to enable maintenance mode. Default true.
+	 * @param int  $upgrading     The timestamp set in the .maintenance file.
+	 */
+	if ( ! apply_filters( 'enable_maintenance_mode', true, $upgrading ) ) {
+		return false;
+	}
+
+	return true;
+}
+
 /**
  * Start the WordPress micro-timer.
  *