From 947eef9468a25bbf44deae772bc4d29103578a14 Mon Sep 17 00:00:00 2001
From: Jeremy Felt <jeremy.felt@gmail.com>
Date: Sun, 14 Jun 2015 21:45:25 +0000
Subject: [PATCH] Introduce get_main_network_id()

Expand on the logic previously available as part of `is_main_network()` and provide a way to obtain the ID of the main network. Most useful in multi-network configurations.

Props @johnjamesjacoby for the initial patch.
Fixes #30294.

Built from https://develop.svn.wordpress.org/trunk@32775


git-svn-id: http://core.svn.wordpress.org/trunk@32746 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/functions.php | 57 ++++++++++++++++++++++++++++-----------
 wp-includes/version.php   |  2 +-
 2 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index b09ed844af..99cf913d9a 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -3873,38 +3873,63 @@ function is_main_site( $site_id = null ) {
  *
  * @since 3.7.0
  *
- * @global wpdb $wpdb
- *
  * @param int $network_id Optional. Network ID to test. Defaults to current network.
  * @return bool True if $network_id is the main network, or if not running Multisite.
  */
 function is_main_network( $network_id = null ) {
-	global $wpdb;
-
-	if ( ! is_multisite() )
+	if ( ! is_multisite() ) {
 		return true;
+	}
 
 	$current_network_id = (int) get_current_site()->id;
 
-	if ( ! $network_id )
+	if ( null === $network_id ) {
 		$network_id = $current_network_id;
+	}
+
 	$network_id = (int) $network_id;
 
-	if ( defined( 'PRIMARY_NETWORK_ID' ) )
-		return $network_id === (int) PRIMARY_NETWORK_ID;
+	return ( $network_id === get_main_network_id() );
+}
 
-	if ( 1 === $current_network_id )
-		return $network_id === $current_network_id;
+/**
+ * Get the main network ID.
+ *
+ * @since 4.3.0
+ *
+ * @global wpdb $wpdb
+ *
+ * @return int The ID of the main network.
+ */
+function get_main_network_id() {
+	global $wpdb;
 
-	$primary_network_id = (int) wp_cache_get( 'primary_network_id', 'site-options' );
+	if ( ! is_multisite() ) {
+		return 1;
+	}
 
-	if ( $primary_network_id )
-		return $network_id === $primary_network_id;
+	if ( defined( 'PRIMARY_NETWORK_ID' ) ) {
+		$main_network_id = PRIMARY_NETWORK_ID;
+	} elseif ( 1 === (int) get_current_site()->id ) {
+		// If the current network has an ID of 1, assume it is the main network.
+		$main_network_id = 1;
+	} else {
+		$main_network_id = wp_cache_get( 'primary_network_id', 'site-options' );
 
-	$primary_network_id = (int) $wpdb->get_var( "SELECT id FROM $wpdb->site ORDER BY id LIMIT 1" );
-	wp_cache_add( 'primary_network_id', $primary_network_id, 'site-options' );
+		if ( false === $main_network_id ) {
+			$main_network_id = (int) $wpdb->get_var( "SELECT id FROM {$wpdb->site} ORDER BY id LIMIT 1" );
+			wp_cache_add( 'primary_network_id', $main_network_id, 'site-options' );
+		}
+	}
 
-	return $network_id === $primary_network_id;
+	/**
+	 * Filter the main network ID.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @param int $main_network_id The ID of the main network.
+	 */
+	return (int) apply_filters( 'get_main_network_id', $main_network_id );
 }
 
 /**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 8498a3b6d5..8af736353d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-alpha-32774';
+$wp_version = '4.3-alpha-32775';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.