Add a way for packagers to override some installation details

...after a discussion with Debian packagers. They can now override installer
classes and change LocalSettings.php the installer generates. The file
intended for such overrides, mw-config/overrides.php, has intentionally been
placed outside of includes to underline the "don't change includes" paradigm.

Change-Id: Id82b90f6740307609bc6c6f4fb8765bc3484dbe7

docs/distributors.txt

@@ -87,9 +87,9 @@ which the user can edit by hand thereafter.  It's just a plain old PHP file,
 and can contain any PHP statements.  It usually sets global variables that are
 used for configuration, and includes files used by any extensions.
 
-Distributors cannot easily add extra statements to the autogenerated
-LocalSettings.php at the present time -- although hacking mw-config/index.php
-would work.  It would be nice if this situation could be improved.
+Distributors can easily add extra statements to the autogenerated
+LocalSettings.php by changing mw-config/overrides.php (see that file for details
+and examples).
 
 There's a new maintenance/install.php script which could be used for performing
 an install through the command line.

includes/AutoLoader.php

@@ -992,6 +992,9 @@ $wgAutoloadLocalClasses = array(
 	'AnsiTermColorer'  => 'maintenance/term/MWTerm.php',
 	'DummyTermColorer' => 'maintenance/term/MWTerm.php',
 
+	# mw-config
+	'InstallerOverrides' => 'mw-config/overrides.php',
+
 	# tests
 	'DbTestPreviewer' => 'tests/testHelpers.inc',
 	'DbTestRecorder' => 'tests/testHelpers.inc',

includes/installer/CliInstaller.php

@@ -132,7 +132,7 @@ class CliInstaller extends Installer {
 	 * @param $path String Full path to write LocalSettings.php to
 	 */
 	public function writeConfigurationFile( $path ) {
-		$ls = new LocalSettingsGenerator( $this );
+		$ls = InstallerOverrides::getLocalSettingsGenerator( $this );
 		$ls->writeFile( "$path/LocalSettings.php" );
 	}
 

includes/installer/LocalSettingsGenerator.php

@@ -29,16 +29,16 @@
  */
 class LocalSettingsGenerator {
 
-	private $extensions = array();
-	private $values = array();
-	private $groupPermissions = array();
-	private $dbSettings = '';
-	private $safeMode = false;
+	protected $extensions = array();
+	protected $values = array();
+	protected $groupPermissions = array();
+	protected $dbSettings = '';
+	protected $safeMode = false;
 
 	/**
 	 * @var Installer
 	 */
-	private $installer;
+	protected $installer;
 
 	/**
 	 * Constructor.
@@ -166,7 +166,7 @@ class LocalSettingsGenerator {
 	/**
 	 * @return String
 	 */
-	private function buildMemcachedServerList() {
+	protected function buildMemcachedServerList() {
 		$servers = $this->values['_MemCachedServers'];
 
 		if( !$servers ) {
@@ -187,7 +187,7 @@ class LocalSettingsGenerator {
 	/**
 	 * @return String
 	 */
-	private function getDefaultText() {
+	protected function getDefaultText() {
 		if( !$this->values['wgImageMagickConvertCommand'] ) {
 			$this->values['wgImageMagickConvertCommand'] = '/usr/bin/convert';
 			$magic = '#';

includes/installer/WebInstaller.php

@@ -161,7 +161,7 @@ class WebInstaller extends Installer {
 				'Content-Disposition: attachment; filename="LocalSettings.php"'
 			);
 
-			$ls = new LocalSettingsGenerator( $this );
+			$ls = InstallerOverrides::getLocalSettingsGenerator( $this );
 			$rightsProfile = $this->rightsProfiles[$this->getVar( '_RightsProfile' )];
 			foreach( $rightsProfile as $group => $rightsArr ) {
 				$ls->setGroupRights( $group, $rightsArr );

maintenance/install.php

@@ -81,7 +81,7 @@ class CommandLineInstaller extends Maintenance {
 		}
 
 		$installer =
-			new CliInstaller( $siteName, $adminName, $this->mOptions );
+			InstallerOverrides::getCliInstaller( $siteName, $adminName, $this->mOptions );
 
 		$status = $installer->doEnvironmentChecks();
 		if( $status->isGood() ) {

mw-config/index.php

@@ -20,7 +20,7 @@ wfInstallerMain();
 function wfInstallerMain() {
 	global $wgRequest, $wgLang, $wgMetaNamespace, $wgCanonicalNamespaceNames;
 
-	$installer = new WebInstaller( $wgRequest );
+	$installer = InstallerOverrides::getWebInstaller( $wgRequest );
 
 	if ( !$installer->startSession() ) {
 		$installer->finish();

mw-config/overrides.php

@@ -0,0 +1,63 @@
+<?php
+/**
+ * MediaWiki installer overrides.
+ * Modify this file if you are a packager who needs to modify the behavior of the MediaWiki installer.
+ * Altering it is preferred over changing anything in /includes.
+ *
+ * Note: this file doesn't gets included from a global scope, don't use globals directly.
+ */
+
+/*
+
+Example of modifications:
+
+	public static function getLocalSettingsGenerator( Installer $installer ) {
+		return new MyLocalSettingsGenerator( $installer );
+	}
+
+Then add the following to the bottom of this file:
+
+class MyLocalSettingsGenerator extends LocalSettingsGenerator {
+	function getText() {
+		// Modify an existing setting
+		$this->values['wgResourceLoaderMaxQueryLength'] = 512;
+		// add a new setting
+		$ls = parent::getText();
+		return $ls . "\n\$wgUseTex = true;\n";
+	}
+}
+*/
+
+/**
+ * @since 1.20
+ */
+class InstallerOverrides {
+	/**
+	 * Instantiates and returns an instance of LocalSettingsGenerator or its descendant classes
+	 * @param Installer $installer
+	 * @return LocalSettingsGenerator
+	 */
+	public static function getLocalSettingsGenerator( Installer $installer ) {
+		return new LocalSettingsGenerator( $installer );
+	}
+
+	/**
+	 * Instantiates and returns an instance of WebInstaller or its descendant classes
+	 * @param WebRequest $request
+	 * @return WebInstaller
+	 */
+	public static function getWebInstaller( WebRequest $request ) {
+		return new WebInstaller( $request );
+	}
+
+	/**
+	 * Instantiates and returns an instance of CliInstaller or its descendant classes
+	 * @param string $siteName
+	 * @param string|null $admin
+	 * @param array $options
+	 * @return CliInstaller
+	 */
+	public static function getCliInstaller( $siteName, $admin = null, array $options = array() ) {
+		return new CliInstaller( $siteName, $admin, $options );
+	}
+}