wp-blog-header.php

<?php
//检测变量$wp_did_heeader是否设置
if (! isset($wp_did_header)):
//给出一个包含有指向一个文件的全路径的字符串，本函数返回去掉文件名后的目录名
if ( !file_exists( dirname(__FILE__) . '/wp-config.php') ) {
	if ( strstr( $_SERVER['PHP_SELF'], 'wp-admin') ) $path = '';
	else $path = 'wp-admin/';
    die("There doesn't seem to be a <code>wp-config.php</code> file. I need this before we can get started. Need more help? <a href='http://wordpress.org/docs/faq/#wp-config'>We got it</a>. You can <a href='{$path}setup-config.php'>create a <code>wp-config.php</code> file through a web interface</a>, but this doesn't work for all server setups. The safest way is to manually create the file.");
}

$wp_did_header = true;

require_once( dirname(__FILE__) . '/wp-config.php');

$query_vars = array();

    //$homesss = get_settings('home');
    // echo $homesss.'sss'; //输出空

// Process PATH_INFO and 404.
if ((isset($_GET['error']) && $_GET['error'] == '404') ||
		((! empty($_SERVER['PATH_INFO'])) && //包含由客户端提供的、跟在真实脚本名称之后并且在查询语句（query string）之前的路径信息，如果存在的话
		('/' != $_SERVER['PATH_INFO']) &&
		 (false === strpos($_SERVER['PATH_INFO'], '.php')) ///返回 needle 存在于 haystack 字符串起始的位置(独立于 offset)。同时注意字符串位置是从0开始，而不是从1开始的
		)) {

	// If we match a rewrite rule, this will be cleared.
	$error = '404';

	// Fetch the rewrite rules.
    //在classes.php中
	$rewrite = $wp_rewrite->wp_rewrite_rules();
    //var_dump($rewrite);
	if (! empty($rewrite)) {
		$pathinfo = $_SERVER['PATH_INFO'];
		$req_uri = $_SERVER['REQUEST_URI'];
        //echo $req_uri;
		$home_path = parse_url(get_settings('home'));
		$home_path = $home_path['path'];

		// Trim path info from the end and the leading home path from the
		// front.  For path info requests, this leaves us with the requesting
		// filename, if any.  For 404 requests, this leaves us with the
		// requested permalink.	
		$req_uri = str_replace($pathinfo, '', $req_uri);
		$req_uri = str_replace($home_path, '', $req_uri);
		$req_uri = trim($req_uri, '/');
		$pathinfo = trim($pathinfo, '/');

		// The requested permalink is in $pathinfo for path info requests and
		//  $req_uri for other requests.
		if (! empty($pathinfo)) {
			$request = $pathinfo;
		} else {
			$request = $req_uri;
		}

		// Look for matches.
		$request_match = $request;
		foreach ($rewrite as $match => $query) {
			// If the requesting file is the anchor of the match, prepend it
			// to the path info.
	    if ((! empty($req_uri)) && (strpos($match, $req_uri) === 0)) {
	      $request_match = $req_uri . '/' . $request;
	    }

			if (preg_match("!^$match!", $request_match, $matches)) {
				// Got a match.
				// Trim the query of everything up to the '?'.
				$query = preg_replace("!^.+\?!", '', $query);

				// Substitute the substring matches into the query.
				eval("\$query = \"$query\";");

				// Parse the query.
				parse_str($query, $query_vars);

				// If we're processing a 404 request, clear the error var
				// since we found something.
				if (isset($_GET['error'])) {
					unset($_GET['error']);
				}

				if (isset($error)) {
					unset($error);
				}

				break;
			}
		}
	}
 }

$wpvarstoreset = array('m','p','posts','w', 'cat','withcomments','s','search','exact', 'sentence', 'debug', 'calendar','page','paged','more','tb', 'pb','author','order','orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'feed', 'author_name', 'static', 'pagename', 'page_id', 'error', 'comments_popup');


$wpvarstoreset = apply_filters('query_vars', $wpvarstoreset);
//var_dump($wpvarstoreset);//默认返回定义的array
for ($i=0; $i<count($wpvarstoreset); $i += 1) {
	$wpvar = $wpvarstoreset[$i];
	if (!isset($$wpvar)) {
        //echo $wpvar;
		if (empty($_POST[$wpvar])) {
			if (empty($_GET[$wpvar]) && empty($query_vars[$wpvar])) {
				$$wpvar = '';
                //echo $wpvar;
			} elseif (!empty($_GET[$wpvar])) {
				$$wpvar = $_GET[$wpvar];
			} else {
				$$wpvar = $query_vars[$wpvar];
			}
		} else {
			$$wpvar = $_POST[$wpvar];
		}
	}
}

// Sending HTTP headers

if ( !empty($error) && '404' == $error ) {
	if ( preg_match('/cgi/', php_sapi_name()) )
		@header('Status: 404 Not Found');
	else
		@header('HTTP/1.x 404 Not Found');
 } else if ( empty($feed) ) {//$feed 在$wpvarstoreset中
	@header('X-Pingback: '. get_bloginfo('pingback_url'));
	@header('Content-type: ' . get_option('html_type') . '; charset=' . get_option('blog_charset'));
} else {
    //echo $withcomments;
	// We're showing a feed, so WP is indeed the only thing that last changed
	if ( $withcomments )//在$wpvarstoreset中
		$wp_last_modified = mysql2date('D, d M Y H:i:s', get_lastcommentmodified('GMT'), 0).' GMT';
	else 
		$wp_last_modified = mysql2date('D, d M Y H:i:s', get_lastpostmodified('GMT'), 0).' GMT';
	$wp_etag = '"' . md5($wp_last_modified) . '"';
	@header("Last-Modified: $wp_last_modified");
	@header("ETag: $wp_etag");
	@header('X-Pingback: ' . get_bloginfo('pingback_url'));

	// Support for Conditional GET
	if (isset($_SERVER['HTTP_IF_NONE_MATCH'])) $client_etag = stripslashes($_SERVER['HTTP_IF_NONE_MATCH']);
	else $client_etag = false;

	$client_last_modified = trim( $_SERVER['HTTP_IF_MODIFIED_SINCE']);
	// If string is empty, return 0. If not, attempt to parse into a timestamp
	$client_modified_timestamp = $client_last_modified ? strtotime($client_last_modified) : 0;

	// Make a timestamp for our most recent modification...	
	$wp_modified_timestamp = strtotime($wp_last_modified);

	if ( ($client_last_modified && $client_etag) ?
		(($client_modified_timestamp >= $wp_modified_timestamp) && ($client_etag == $wp_etag)) :
		(($client_modified_timestamp >= $wp_modified_timestamp) || ($client_etag == $wp_etag)) ) {
		if ( preg_match('/cgi/',php_sapi_name()) ) {
			header('Status: 304 Not Modified');
			echo "\r\n\r\n";
			exit;
		} else {
			if ( version_compare(phpversion(), '4.3.0', '>=') )
				header('Not Modified', TRUE, 304);
			else
				header('HTTP/1.x 304 Not Modified');
			exit;
		}
	}
}

$use_gzipcompression = get_settings('gzipcompression');
//var_dump($use_gzipcompression);//false

$more_wpvars = array('posts_per_page', 'posts_per_archive_page', 'what_to_show', 'showposts', 'nopaging');

// Construct the query string.
$query_string = '';
    //这里获得p=1参数
foreach (array_merge($wpvarstoreset, $more_wpvars) as $wpvar) {
	if ($$wpvar != '') {
		$query_string .= (strlen($query_string) < 1) ? '' : '&';
		$query_string .= $wpvar . '=' . rawurlencode($$wpvar);
	}
}
    //echo $query_string;
$query_string = apply_filters('query_string', $query_string);

update_category_cache();
get_currentuserinfo();

// Call query posts to do the work.
//echo $query_string;
//哦 在这里
$posts = & query_posts($query_string);

// Extract updated query vars back into global namespace.
//导入到全局变量中去
//var_dump($wp_query->query_vars);
extract($wp_query->query_vars);

//echo $withcomments.' show'; extract的结果 如果url中包含withcomments=true的querystring
if ( is_single() || is_page() ) {
	$more = 1;
    $single = 1;
}

// Issue a 404 if a permalink request doesn't match any posts.  Don't issue a
// 404 if one was already issued, if the request was a search, or if the
// request was a regular query string request rather than a permalink request.
if ( (0 == count($posts)) && !is_404() && !is_search()
		&& ( isset($rewrite) || (!empty($_SERVER['QUERY_STRING']) &&
		(false === strpos($_SERVER['REQUEST_URI'], '?'))) ) ) {
	$wp_query->is_404 = true;
	if ( preg_match('/cgi/', php_sapi_name()) )
		@header('Status: 404 Not Found');
	else
		@header('HTTP/1.x 404 Not Found');
}

if ($pagenow != 'post.php' && $pagenow != 'edit.php') {
	if ( get_settings('gzipcompression') ) 
		gzip_compression();
}
    //echo $_SERVER["REQUEST_URI"];
// Template redirection
//index.php中默认定义了WP_USE_THEMES
//constant($name) 返回一个常量的值 
if ( defined('WP_USE_THEMES') && constant('WP_USE_THEMES') ) {
	do_action('template_redirect');
	if ( is_feed() && empty($doing_rss) ) {
		include(ABSPATH . '/wp-feed.php');
		exit;
	} else if ( is_trackback() && empty($doing_trackback) ) {
		include(ABSPATH . '/wp-trackback.php');
		exit;
	} else if ( is_404() && get_404_template() ) {
		include(get_404_template());
		exit;
	} else if ( is_search() && get_search_template() ) {
		include(get_search_template());
		exit;
	} else if ( is_home() && get_home_template() ) {
		include(get_home_template());
		exit;
	} else if ( is_single() && get_single_template() ) {
        //跳转到具体某篇文章
		include(get_single_template());
		exit;
	} else if ( is_page() && get_page_template() ) {
		include(get_page_template());
		exit;
	} else if ( is_category() && get_category_template()) {
		include(get_category_template());
		exit;		
	} else if ( is_author() && get_author_template() ) {
		include(get_author_template());
		exit;
	} else if ( is_date() && get_date_template() ) {
		include(get_date_template());
		exit;
	} else if ( is_archive() && get_archive_template() ) {
		include(get_archive_template());
		exit;
	} else if ( is_comments_popup() && get_comments_popup_template() ) {
		include(get_comments_popup_template());
		exit;
	} else if ( is_paged() && get_paged_template() ) {
		include(get_paged_template());
		exit;
	} else if ( file_exists(TEMPLATEPATH . "/index.php") ) {
        //首页
		include(TEMPLATEPATH . "/index.php");
		exit;
	}
} else {
	// Process feeds and trackbacks even if not using themes.
	if ( is_feed() && empty($doing_rss) ) {
		include(ABSPATH . '/wp-feed.php');
		exit;
	} else if ( is_trackback() && empty($doing_trackback) ) {
		include(ABSPATH . '/wp-trackback.php');
		exit;
	}
}

endif;
?>