WordPress/wp-admin/includes/export.php

<?php

// version number for the export format.  bump this when something changes that might affect compatibility.
define('WXR_VERSION', '1.0');

function export_wp($author='') {
global $wpdb, $post_ids, $post;

do_action('export_wp');

$filename = 'wordpress.' . date('Y-m-d') . '.xml';

header('Content-Description: File Transfer');
header("Content-Disposition: attachment; filename=$filename");
header('Content-Type: text/xml; charset=' . get_option('blog_charset'), true);

$where = '';
if ( $author and $author != 'all' ) {
	$author_id = (int) $author;
	$where = " WHERE post_author = '$author_id' ";
}

// grab a snapshot of post IDs, just in case it changes during the export
$post_ids = $wpdb->get_col("SELECT ID FROM $wpdb->posts $where ORDER BY post_date_gmt ASC");

$categories = (array) get_categories('get=all');
$tags = (array) get_tags('get=all');

function wxr_missing_parents($categories) {
	if ( !is_array($categories) || empty($categories) )
		return array();

	foreach ( $categories as $category )
		$parents[$category->term_id] = $category->parent;

	$parents = array_unique(array_diff($parents, array_keys($parents)));

	if ( $zero = array_search('0', $parents) )
		unset($parents[$zero]);

	return $parents;
}

while ( $parents = wxr_missing_parents($categories) ) {
	$found_parents = get_categories("include=" . join(', ', $parents));
	if ( is_array($found_parents) && count($found_parents) )
		$categories = array_merge($categories, $found_parents);
	else
		break;
}

// Put them in order to be inserted with no child going before its parent
$pass = 0;
$passes = 1000 + count($categories);
while ( ( $cat = array_shift($categories) ) && ++$pass < $passes ) {
	if ( $cat->parent == 0 || isset($cats[$cat->parent]) ) {
		$cats[$cat->term_id] = $cat;
	} else {
		$categories[] = $cat;
	}
}
unset($categories);

function wxr_cdata($str) {
	if ( seems_utf8($str) == false )
		$str = utf8_encode($str);

	// $str = ent2ncr(wp_specialchars($str));

	$str = "<![CDATA[$str" . ( ( substr($str, -1) == ']' ) ? ' ' : '') . "]]>";

	return $str;
}

function wxr_site_url() {
	global $current_site;
	
	// mu: the base url
	if ( isset($current_site->domain) ) {
		return 'http://'.$current_site->domain.$current_site->path;
	}
	// wp: the blog url
	else {
		return get_bloginfo_rss('url');
	}
}

function wxr_cat_name($c) {
	if ( empty($c->name) )
		return;

	echo '<wp:cat_name>' . wxr_cdata($c->name) . '</wp:cat_name>';
}

function wxr_category_description($c) {
	if ( empty($c->description) )
		return;

	echo '<wp:category_description>' . wxr_cdata($c->description) . '</wp:category_description>';
}

function wxr_tag_name($t) {
	if ( empty($t->name) )
		return;

	echo '<wp:tag_name>' . wxr_cdata($t->name) . '</wp:tag_name>';
}

function wxr_tag_description($t) {
	if ( empty($t->description) )
		return;

	echo '<wp:tag_description>' . wxr_cdata($t->description) . '</wp:tag_description>';
}

function wxr_post_taxonomy() {
	$categories = get_the_category();
	$tags = get_the_tags();
	$the_list = '';
	$filter = 'rss';

	if ( !empty($categories) ) foreach ( (array) $categories as $category ) {
		$cat_name = sanitize_term_field('name', $category->name, $category->term_id, 'category', $filter);
		// for backwards compatibility
		$the_list .= "\n\t\t<category><![CDATA[$cat_name]]></category>\n";
		// forwards compatibility: use a unique identifier for each cat to avoid clashes
		// http://trac.wordpress.org/ticket/5447
		$the_list .= "\n\t\t<category domain=\"category\" nicename=\"{$category->slug}\"><![CDATA[$cat_name]]></category>\n";
	}

	if ( !empty($tags) ) foreach ( (array) $tags as $tag ) {
		$tag_name = sanitize_term_field('name', $tag->name, $tag->term_id, 'post_tag', $filter);
		$the_list .= "\n\t\t<category domain=\"tag\"><![CDATA[$tag_name]]></category>\n";
		// forwards compatibility as above
		$the_list .= "\n\t\t<category domain=\"tag\" nicename=\"{$tag->slug}\"><![CDATA[$tag_name]]></category>\n";
	}

	echo $the_list;
}

echo '<?xml version="1.0" encoding="' . get_bloginfo('charset') . '"?' . ">\n";

?>
<!-- This is a WordPress eXtended RSS file generated by WordPress as an export of your blog. -->
<!-- It contains information about your blog's posts, comments, and categories. -->
<!-- You may use this file to transfer that content from one site to another. -->
<!-- This file is not intended to serve as a complete backup of your blog. -->

<!-- To import this information into a WordPress blog follow these steps. -->
<!-- 1. Log into that blog as an administrator. -->
<!-- 2. Go to Manage: Import in the blog's admin panels. -->
<!-- 3. Choose "WordPress" from the list. -->
<!-- 4. Upload this file using the form provided on that page. -->
<!-- 5. You will first be asked to map the authors in this export file to users -->
<!--    on the blog.  For each author, you may choose to map to an -->
<!--    existing user on the blog or to create a new user -->
<!-- 6. WordPress will then import each of the posts, comments, and categories -->
<!--    contained in this file into your blog -->

<?php the_generator('export');?>
<rss version="2.0"
	xmlns:content="http://purl.org/rss/1.0/modules/content/"
	xmlns:wfw="http://wellformedweb.org/CommentAPI/"
	xmlns:dc="http://purl.org/dc/elements/1.1/"
	xmlns:wp="http://wordpress.org/export/<?php echo WXR_VERSION; ?>/"
>

<channel>
	<title><?php bloginfo_rss('name'); ?></title>
	<link><?php bloginfo_rss('url') ?></link>
	<description><?php bloginfo_rss("description") ?></description>
	<pubDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_lastpostmodified('GMT'), false); ?></pubDate>
	<generator>http://wordpress.org/?v=<?php bloginfo_rss('version'); ?></generator>
	<language><?php echo get_option('rss_language'); ?></language>
	<wp:wxr_version><?php echo WXR_VERSION; ?></wp:wxr_version>
	<wp:base_site_url><?php echo wxr_site_url(); ?></wp:base_site_url>
	<wp:base_blog_url><?php bloginfo_rss('url'); ?></wp:base_blog_url>
<?php if ( $cats ) : foreach ( $cats as $c ) : ?>
	<wp:category><wp:category_nicename><?php echo $c->slug; ?></wp:category_nicename><wp:category_parent><?php echo $c->parent ? $cats[$c->parent]->name : ''; ?></wp:category_parent><?php wxr_cat_name($c); ?><?php wxr_category_description($c); ?></wp:category>
<?php endforeach; endif; ?>
<?php if ( $tags ) : foreach ( $tags as $t ) : ?>
	<wp:tag><wp:tag_slug><?php echo $t->slug; ?></wp:tag_slug><?php wxr_tag_name($t); ?><?php wxr_tag_description($t); ?></wp:tag>
<?php endforeach; endif; ?>
	<?php do_action('rss2_head'); ?>
	<?php if ($post_ids) {
		global $wp_query;
		$wp_query->in_the_loop = true;  // Fake being in the loop.
		// fetch 20 posts at a time rather than loading the entire table into memory
		while ( $next_posts = array_splice($post_ids, 0, 20) ) {
			$where = "WHERE ID IN (".join(',', $next_posts).")";
			$posts = $wpdb->get_results("SELECT * FROM $wpdb->posts $where ORDER BY post_date_gmt ASC");
				foreach ($posts as $post) {
			setup_postdata($post); ?>
<item>
<title><?php the_title_rss() ?></title>
<link><?php the_permalink_rss() ?></link>
<pubDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_post_time('Y-m-d H:i:s', true), false); ?></pubDate>
<dc:creator><?php the_author() ?></dc:creator>
<?php wxr_post_taxonomy() ?>

<guid isPermaLink="false"><?php the_guid(); ?></guid>
<description></description>
<content:encoded><![CDATA[<?php echo $post->post_content ?>]]></content:encoded>
<wp:post_id><?php echo $post->ID; ?></wp:post_id>
<wp:post_date><?php echo $post->post_date; ?></wp:post_date>
<wp:post_date_gmt><?php echo $post->post_date_gmt; ?></wp:post_date_gmt>
<wp:comment_status><?php echo $post->comment_status; ?></wp:comment_status>
<wp:ping_status><?php echo $post->ping_status; ?></wp:ping_status>
<wp:post_name><?php echo $post->post_name; ?></wp:post_name>
<wp:status><?php echo $post->post_status; ?></wp:status>
<wp:post_parent><?php echo $post->post_parent; ?></wp:post_parent>
<wp:menu_order><?php echo $post->menu_order; ?></wp:menu_order>
<wp:post_type><?php echo $post->post_type; ?></wp:post_type>
<?php
if ($post->post_type == 'attachment') { ?>
<wp:attachment_url><?php echo wp_get_attachment_url($post->ID); ?></wp:attachment_url>
<?php } ?>
<?php
$postmeta = $wpdb->get_results("SELECT * FROM $wpdb->postmeta WHERE post_id = $post->ID");
if ( $postmeta ) {
?>
<?php foreach( $postmeta as $meta ) { ?>
<wp:postmeta>
<wp:meta_key><?php echo $meta->meta_key; ?></wp:meta_key>
<wp:meta_value><?Php echo $meta->meta_value; ?></wp:meta_value>
</wp:postmeta>
<?php } ?>
<?php } ?>
<?php
$comments = $wpdb->get_results("SELECT * FROM $wpdb->comments WHERE comment_post_ID = $post->ID");
if ( $comments ) { foreach ( $comments as $c ) { ?>
<wp:comment>
<wp:comment_id><?php echo $c->comment_ID; ?></wp:comment_id>
<wp:comment_author><?php echo wxr_cdata($c->comment_author); ?></wp:comment_author>
<wp:comment_author_email><?php echo $c->comment_author_email; ?></wp:comment_author_email>
<wp:comment_author_url><?php echo $c->comment_author_url; ?></wp:comment_author_url>
<wp:comment_author_IP><?php echo $c->comment_author_IP; ?></wp:comment_author_IP>
<wp:comment_date><?php echo $c->comment_date; ?></wp:comment_date>
<wp:comment_date_gmt><?php echo $c->comment_date_gmt; ?></wp:comment_date_gmt>
<wp:comment_content><?php echo $c->comment_content; ?></wp:comment_content>
<wp:comment_approved><?php echo $c->comment_approved; ?></wp:comment_approved>
<wp:comment_type><?php echo $c->comment_type; ?></wp:comment_type>
<wp:comment_parent><?php echo $c->comment_parent; ?></wp:comment_parent>
<wp:comment_user_id><?php echo $c->user_id; ?></wp:comment_user_id>
</wp:comment>
<?php } } ?>
	</item>
<?php } } } ?>
</channel>
</rss>
<?php
}

?>