【WordPress】wp-load.php

<?php
/**
 * Bootstrap file for setting the ABSPATH constant
 * and loading the wp-config.php file. The wp-config.php
 * file will then load the wp-settings.php file, which
 * will then set up the WordPress environment.
 *
 * If the wp-config.php file is not found then an error
 * will be displayed asking the visitor to set up the
 * wp-config.php file.
 *
 * Will also search for wp-config.php in WordPress' parent
 * directory to allow the WordPress directory to remain
 * untouched.
 *
 * @package WordPress
 */

/** Define ABSPATH as this file's directory */
if ( ! defined( 'ABSPATH' ) ) {
	define( 'ABSPATH', __DIR__ . '/' );
}

/*
 * The error_reporting() function can be disabled in php.ini. On systems where that is the case,
 * it's best to add a dummy function to the wp-config.php file, but as this call to the function
 * is run prior to wp-config.php loading, it is wrapped in a function_exists() check.
 */
if ( function_exists( 'error_reporting' ) ) {
	/*
	 * Initialize error reporting to a known set of levels.
	 *
	 * This will be adapted in wp_debug_mode() located in wp-includes/load.php based on WP_DEBUG.
	 * @see https://www.php.net/manual/en/errorfunc.constants.php List of known error levels.
	 */
	error_reporting( E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_ERROR | E_WARNING | E_PARSE | E_USER_ERROR | E_USER_WARNING | E_RECOVERABLE_ERROR );
}

/*
 * If wp-config.php exists in the WordPress root, or if it exists in the root and wp-settings.php
 * doesn't, load wp-config.php. The secondary check for wp-settings.php has the added benefit
 * of avoiding cases where the current directory is a nested installation, e.g. / is WordPress(a)
 * and /blog/ is WordPress(b).
 *
 * If neither set of conditions is true, initiate loading the setup process.
 */
if ( file_exists( ABSPATH . 'wp-config.php' ) ) {

	/** The config file resides in ABSPATH */
	require_once ABSPATH . 'wp-config.php';

} elseif ( @file_exists( dirname( ABSPATH ) . '/wp-config.php' ) && ! @file_exists( dirname( ABSPATH ) . '/wp-settings.php' ) ) {

	/** The config file resides one level above ABSPATH but is not part of another installation */
	require_once dirname( ABSPATH ) . '/wp-config.php';

} else {

	// A config file doesn't exist.

	define( 'WPINC', 'wp-includes' );
	require_once ABSPATH . WPINC . '/version.php';
	require_once ABSPATH . WPINC . '/compat.php';
	require_once ABSPATH . WPINC . '/load.php';

	// Check for the required PHP version and for the MySQL extension or a database drop-in.
	wp_check_php_mysql_versions();

	// Standardize $_SERVER variables across setups.
	wp_fix_server_vars();

	define( 'WP_CONTENT_DIR', ABSPATH . 'wp-content' );
	require_once ABSPATH . WPINC . '/functions.php';

	$path = wp_guess_url() . '/wp-admin/setup-config.php';

	// Redirect to setup-config.php.
	if ( ! str_contains( $_SERVER['REQUEST_URI'], 'setup-config' ) ) {
		header( 'Location: ' . $path );
		exit;
	}

	wp_load_translations_early();

	// Die with an error message.
	$die = '<p>' . sprintf(
		/* translators: %s: wp-config.php */
		__( "There doesn't seem to be a %s file. It is needed before the installation can continue." ),
		'<code>wp-config.php</code>'
	) . '</p>';
	$die .= '<p>' . sprintf(
		/* translators: 1: Documentation URL, 2: wp-config.php */
		__( 'Need more help? <a href="%1$s">Read the support article on %2$s</a>.' ),
		__( 'https://wordpress.org/documentation/article/editing-wp-config-php/' ),
		'<code>wp-config.php</code>'
	) . '</p>';
	$die .= '<p>' . sprintf(
		/* translators: %s: wp-config.php */
		__( "You can create a %s file through a web interface, but this doesn't work for all server setups. The safest way is to manually create the file." ),
		'<code>wp-config.php</code>'
	) . '</p>';
	$die .= '<p><a href="' . $path . '" class="button button-large">' . __( 'Create a Configuration File' ) . '</a></p>';

	wp_die( $die, __( 'WordPress &rsaquo; Error' ) );
}

这段PHP脚本是WordPress应用的一部分，它的主要目的是加载一些必要的文件，并进行一些基本的环境检查。

首先，它加载了一些核心的WordPress文件，包括版本信息(version.php)、兼容性函数(compat.php)和加载函数(load.php)。

然后，它调用wp_check_php_mysql_versions()函数来检查当前环境的PHP版本以及是否安装了MySQL扩展或者数据库插件。

接着，它调用wp_fix_server_vars()函数来标准化$_SERVER变量，以确保在不同的环境下这些变量的行为是一致的。

然后，它定义了WP_CONTENT_DIR常量，这个常量指向WordPress的内容目录，然后加载了一些基本的WordPress函数(functions.php)。

接下来，它构造了一个指向setup-config.php的URL，并检查当前的请求URL是否包含setup-config，如果不包含，那么就会重定向到setup-config.php。

然后，它调用wp_load_translations_early()函数来加载早期的翻译。

最后，如果wp-config.php文件不存在，它会显示一个错误信息，告诉用户需要wp-config.php文件才能继续安装，并提供了一个链接到编辑wp-config.php文件的支持文章，以及一个创建配置文件的按钮。如果用户点击这个按钮，就会被重定向到setup-config.php。

如果所有的检查都通过，那么WordPress的安装过程就可以开始了。