mirror of https://github.com/friendica/friendica
214 lines
8.1 KiB
PHP
214 lines
8.1 KiB
PHP
<?php
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/**
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* Parser that uses PHP 5's DOM extension (part of the core).
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*
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* In PHP 5, the DOM XML extension was revamped into DOM and added to the core.
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* It gives us a forgiving HTML parser, which we use to transform the HTML
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* into a DOM, and then into the tokens. It is blazingly fast (for large
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* documents, it performs twenty times faster than
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* HTMLPurifier_Lexer_DirectLex,and is the default choice for PHP 5.
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*
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* @note Any empty elements will have empty tokens associated with them, even if
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* this is prohibited by the spec. This is cannot be fixed until the spec
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* comes into play.
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*
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* @note PHP's DOM extension does not actually parse any entities, we use
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* our own function to do that.
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*
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* @warning DOM tends to drop whitespace, which may wreak havoc on indenting.
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* If this is a huge problem, due to the fact that HTML is hand
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* edited and you are unable to get a parser cache that caches the
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* the output of HTML Purifier while keeping the original HTML lying
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* around, you may want to run Tidy on the resulting output or use
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* HTMLPurifier_DirectLex
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*/
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class HTMLPurifier_Lexer_DOMLex extends HTMLPurifier_Lexer
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{
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private $factory;
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public function __construct() {
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// setup the factory
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parent::__construct();
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$this->factory = new HTMLPurifier_TokenFactory();
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}
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public function tokenizeHTML($html, $config, $context) {
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$html = $this->normalize($html, $config, $context);
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// attempt to armor stray angled brackets that cannot possibly
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// form tags and thus are probably being used as emoticons
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if ($config->get('Core.AggressivelyFixLt')) {
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$char = '[^a-z!\/]';
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$comment = "/<!--(.*?)(-->|\z)/is";
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$html = preg_replace_callback($comment, array($this, 'callbackArmorCommentEntities'), $html);
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do {
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$old = $html;
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$html = preg_replace("/<($char)/i", '<\\1', $html);
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} while ($html !== $old);
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$html = preg_replace_callback($comment, array($this, 'callbackUndoCommentSubst'), $html); // fix comments
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}
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// preprocess html, essential for UTF-8
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$html = $this->wrapHTML($html, $config, $context);
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$doc = new DOMDocument();
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$doc->encoding = 'UTF-8'; // theoretically, the above has this covered
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set_error_handler(array($this, 'muteErrorHandler'));
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$doc->loadHTML($html);
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restore_error_handler();
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$tokens = array();
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$this->tokenizeDOM(
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$doc->getElementsByTagName('html')->item(0)-> // <html>
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getElementsByTagName('body')->item(0)-> // <body>
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getElementsByTagName('div')->item(0) // <div>
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, $tokens);
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return $tokens;
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}
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/**
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* Recursive function that tokenizes a node, putting it into an accumulator.
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*
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* @param $node DOMNode to be tokenized.
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* @param $tokens Array-list of already tokenized tokens.
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* @param $collect Says whether or start and close are collected, set to
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* false at first recursion because it's the implicit DIV
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* tag you're dealing with.
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* @returns Tokens of node appended to previously passed tokens.
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*/
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protected function tokenizeDOM($node, &$tokens, $collect = false) {
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// intercept non element nodes. WE MUST catch all of them,
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// but we're not getting the character reference nodes because
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// those should have been preprocessed
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if ($node->nodeType === XML_TEXT_NODE) {
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$tokens[] = $this->factory->createText($node->data);
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return;
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} elseif ($node->nodeType === XML_CDATA_SECTION_NODE) {
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// undo libxml's special treatment of <script> and <style> tags
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$last = end($tokens);
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$data = $node->data;
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// (note $node->tagname is already normalized)
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if ($last instanceof HTMLPurifier_Token_Start && ($last->name == 'script' || $last->name == 'style')) {
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$new_data = trim($data);
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if (substr($new_data, 0, 4) === '<!--') {
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$data = substr($new_data, 4);
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if (substr($data, -3) === '-->') {
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$data = substr($data, 0, -3);
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} else {
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// Highly suspicious! Not sure what to do...
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}
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}
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}
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$tokens[] = $this->factory->createText($this->parseData($data));
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return;
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} elseif ($node->nodeType === XML_COMMENT_NODE) {
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// this is code is only invoked for comments in script/style in versions
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// of libxml pre-2.6.28 (regular comments, of course, are still
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// handled regularly)
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$tokens[] = $this->factory->createComment($node->data);
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return;
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} elseif (
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// not-well tested: there may be other nodes we have to grab
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$node->nodeType !== XML_ELEMENT_NODE
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) {
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return;
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}
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$attr = $node->hasAttributes() ?
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$this->transformAttrToAssoc($node->attributes) :
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array();
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// We still have to make sure that the element actually IS empty
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if (!$node->childNodes->length) {
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if ($collect) {
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$tokens[] = $this->factory->createEmpty($node->tagName, $attr);
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}
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} else {
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if ($collect) { // don't wrap on first iteration
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$tokens[] = $this->factory->createStart(
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$tag_name = $node->tagName, // somehow, it get's dropped
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$attr
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);
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}
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foreach ($node->childNodes as $node) {
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// remember, it's an accumulator. Otherwise, we'd have
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// to use array_merge
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$this->tokenizeDOM($node, $tokens, true);
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}
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if ($collect) {
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$tokens[] = $this->factory->createEnd($tag_name);
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}
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}
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}
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/**
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* Converts a DOMNamedNodeMap of DOMAttr objects into an assoc array.
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*
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* @param $attribute_list DOMNamedNodeMap of DOMAttr objects.
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* @returns Associative array of attributes.
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*/
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protected function transformAttrToAssoc($node_map) {
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// NamedNodeMap is documented very well, so we're using undocumented
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// features, namely, the fact that it implements Iterator and
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// has a ->length attribute
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if ($node_map->length === 0) return array();
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$array = array();
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foreach ($node_map as $attr) {
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$array[$attr->name] = $attr->value;
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}
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return $array;
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}
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/**
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* An error handler that mutes all errors
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*/
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public function muteErrorHandler($errno, $errstr) {}
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/**
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* Callback function for undoing escaping of stray angled brackets
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* in comments
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*/
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public function callbackUndoCommentSubst($matches) {
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return '<!--' . strtr($matches[1], array('&'=>'&','<'=>'<')) . $matches[2];
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}
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/**
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* Callback function that entity-izes ampersands in comments so that
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* callbackUndoCommentSubst doesn't clobber them
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*/
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public function callbackArmorCommentEntities($matches) {
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return '<!--' . str_replace('&', '&', $matches[1]) . $matches[2];
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}
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/**
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* Wraps an HTML fragment in the necessary HTML
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*/
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protected function wrapHTML($html, $config, $context) {
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$def = $config->getDefinition('HTML');
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$ret = '';
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if (!empty($def->doctype->dtdPublic) || !empty($def->doctype->dtdSystem)) {
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$ret .= '<!DOCTYPE html ';
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if (!empty($def->doctype->dtdPublic)) $ret .= 'PUBLIC "' . $def->doctype->dtdPublic . '" ';
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if (!empty($def->doctype->dtdSystem)) $ret .= '"' . $def->doctype->dtdSystem . '" ';
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$ret .= '>';
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}
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$ret .= '<html><head>';
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$ret .= '<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />';
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// No protection if $html contains a stray </div>!
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$ret .= '</head><body><div>'.$html.'</div></body></html>';
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return $ret;
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}
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}
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// vim: et sw=4 sts=4
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