mirror of
https://github.com/ezyang/htmlpurifier.git
synced 2024-12-22 16:31:53 +00:00
660 lines
27 KiB
PHP
660 lines
27 KiB
PHP
<?php
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/**
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* Takes tokens makes them well-formed (balance end tags, etc.)
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*
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* Specification of the armor attributes this strategy uses:
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*
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* - MakeWellFormed_TagClosedError: This armor field is used to
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* suppress tag closed errors for certain tokens [TagClosedSuppress],
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* in particular, if a tag was generated automatically by HTML
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* Purifier, we may rely on our infrastructure to close it for us
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* and shouldn't report an error to the user [TagClosedAuto].
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*/
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class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
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{
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/**
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* Array stream of tokens being processed.
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* @type HTMLPurifier_Token[]
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*/
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protected $tokens;
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/**
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* Current token.
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* @type HTMLPurifier_Token
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*/
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protected $token;
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/**
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* Zipper managing the true state.
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* @type HTMLPurifier_Zipper
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*/
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protected $zipper;
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/**
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* Current nesting of elements.
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* @type array
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*/
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protected $stack;
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/**
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* Injectors active in this stream processing.
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* @type HTMLPurifier_Injector[]
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*/
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protected $injectors;
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/**
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* Current instance of HTMLPurifier_Config.
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* @type HTMLPurifier_Config
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*/
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protected $config;
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/**
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* Current instance of HTMLPurifier_Context.
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* @type HTMLPurifier_Context
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*/
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protected $context;
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/**
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* @param HTMLPurifier_Token[] $tokens
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* @param HTMLPurifier_Config $config
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* @param HTMLPurifier_Context $context
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* @return HTMLPurifier_Token[]
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* @throws HTMLPurifier_Exception
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*/
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public function execute($tokens, $config, $context)
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{
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$definition = $config->getHTMLDefinition();
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// local variables
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$generator = new HTMLPurifier_Generator($config, $context);
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$escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
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// used for autoclose early abortion
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$global_parent_allowed_elements = $definition->info_parent_def->child->getAllowedElements($config);
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$e = $context->get('ErrorCollector', true);
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$i = false; // injector index
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list($zipper, $token) = HTMLPurifier_Zipper::fromArray($tokens);
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if ($token === NULL) {
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return array();
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}
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$reprocess = false; // whether or not to reprocess the same token
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$stack = array();
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// member variables
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$this->stack =& $stack;
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$this->tokens =& $tokens;
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$this->token =& $token;
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$this->zipper =& $zipper;
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$this->config = $config;
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$this->context = $context;
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// context variables
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$context->register('CurrentNesting', $stack);
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$context->register('InputZipper', $zipper);
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$context->register('CurrentToken', $token);
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// -- begin INJECTOR --
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$this->injectors = array();
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$injectors = $config->getBatch('AutoFormat');
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$def_injectors = $definition->info_injector;
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$custom_injectors = $injectors['Custom'];
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unset($injectors['Custom']); // special case
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foreach ($injectors as $injector => $b) {
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// XXX: Fix with a legitimate lookup table of enabled filters
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if (strpos($injector, '.') !== false) {
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continue;
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}
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$injector = "HTMLPurifier_Injector_$injector";
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if (!$b) {
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continue;
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}
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$this->injectors[] = new $injector;
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}
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foreach ($def_injectors as $injector) {
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// assumed to be objects
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$this->injectors[] = $injector;
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}
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foreach ($custom_injectors as $injector) {
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if (!$injector) {
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continue;
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}
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if (is_string($injector)) {
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$injector = "HTMLPurifier_Injector_$injector";
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$injector = new $injector;
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}
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$this->injectors[] = $injector;
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}
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// give the injectors references to the definition and context
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// variables for performance reasons
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foreach ($this->injectors as $ix => $injector) {
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$error = $injector->prepare($config, $context);
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if (!$error) {
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continue;
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}
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array_splice($this->injectors, $ix, 1); // rm the injector
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trigger_error("Cannot enable {$injector->name} injector because $error is not allowed", E_USER_WARNING);
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}
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// -- end INJECTOR --
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// a note on reprocessing:
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// In order to reduce code duplication, whenever some code needs
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// to make HTML changes in order to make things "correct", the
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// new HTML gets sent through the purifier, regardless of its
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// status. This means that if we add a start token, because it
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// was totally necessary, we don't have to update nesting; we just
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// punt ($reprocess = true; continue;) and it does that for us.
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// isset is in loop because $tokens size changes during loop exec
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for (;;
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// only increment if we don't need to reprocess
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$reprocess ? $reprocess = false : $token = $zipper->next($token)) {
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// check for a rewind
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if (is_int($i)) {
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// possibility: disable rewinding if the current token has a
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// rewind set on it already. This would offer protection from
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// infinite loop, but might hinder some advanced rewinding.
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$rewind_offset = $this->injectors[$i]->getRewindOffset();
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if (is_int($rewind_offset)) {
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for ($j = 0; $j < $rewind_offset; $j++) {
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if (empty($zipper->front)) break;
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$token = $zipper->prev($token);
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// indicate that other injectors should not process this token,
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// but we need to reprocess it. See Note [Injector skips]
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unset($token->skip[$i]);
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$token->rewind = $i;
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if ($token instanceof HTMLPurifier_Token_Start) {
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array_pop($this->stack);
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} elseif ($token instanceof HTMLPurifier_Token_End) {
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$this->stack[] = $token->start;
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}
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}
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}
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$i = false;
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}
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// handle case of document end
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if ($token === NULL) {
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// kill processing if stack is empty
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if (empty($this->stack)) {
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break;
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}
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// peek
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$top_nesting = array_pop($this->stack);
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$this->stack[] = $top_nesting;
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// send error [TagClosedSuppress]
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if ($e && !isset($top_nesting->armor['MakeWellFormed_TagClosedError'])) {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by document end', $top_nesting);
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}
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// append, don't splice, since this is the end
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$token = new HTMLPurifier_Token_End($top_nesting->name);
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// punt!
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$reprocess = true;
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continue;
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}
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//echo '<br>'; printZipper($zipper, $token);//printTokens($this->stack);
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//flush();
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// quick-check: if it's not a tag, no need to process
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if (empty($token->is_tag)) {
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if ($token instanceof HTMLPurifier_Token_Text) {
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foreach ($this->injectors as $i => $injector) {
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if (isset($token->skip[$i])) {
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// See Note [Injector skips]
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continue;
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}
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if ($token->rewind !== null && $token->rewind !== $i) {
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continue;
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}
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// XXX fuckup
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$r = $token;
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$injector->handleText($r);
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$token = $this->processToken($r, $i);
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$reprocess = true;
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break;
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}
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}
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// another possibility is a comment
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continue;
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}
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if (isset($definition->info[$token->name])) {
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$type = $definition->info[$token->name]->child->type;
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} else {
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$type = false; // Type is unknown, treat accordingly
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}
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// quick tag checks: anything that's *not* an end tag
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$ok = false;
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if ($type === 'empty' && $token instanceof HTMLPurifier_Token_Start) {
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// claims to be a start tag but is empty
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$token = new HTMLPurifier_Token_Empty(
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$token->name,
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$token->attr,
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$token->line,
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$token->col,
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$token->armor
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);
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$ok = true;
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} elseif ($type && $type !== 'empty' && $token instanceof HTMLPurifier_Token_Empty) {
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// claims to be empty but really is a start tag
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// NB: this assignment is required
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$old_token = $token;
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$token = new HTMLPurifier_Token_End($token->name);
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$token = $this->insertBefore(
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new HTMLPurifier_Token_Start($old_token->name, $old_token->attr, $old_token->line, $old_token->col, $old_token->armor)
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);
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// punt (since we had to modify the input stream in a non-trivial way)
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$reprocess = true;
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continue;
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} elseif ($token instanceof HTMLPurifier_Token_Empty) {
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// real empty token
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$ok = true;
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} elseif ($token instanceof HTMLPurifier_Token_Start) {
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// start tag
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// ...unless they also have to close their parent
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if (!empty($this->stack)) {
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// Performance note: you might think that it's rather
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// inefficient, recalculating the autoclose information
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// for every tag that a token closes (since when we
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// do an autoclose, we push a new token into the
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// stream and then /process/ that, before
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// re-processing this token.) But this is
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// necessary, because an injector can make an
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// arbitrary transformations to the autoclosing
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// tokens we introduce, so things may have changed
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// in the meantime. Also, doing the inefficient thing is
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// "easy" to reason about (for certain perverse definitions
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// of "easy")
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$parent = array_pop($this->stack);
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$this->stack[] = $parent;
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$parent_def = null;
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$parent_elements = null;
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$autoclose = false;
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if (isset($definition->info[$parent->name])) {
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$parent_def = $definition->info[$parent->name];
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$parent_elements = $parent_def->child->getAllowedElements($config);
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$autoclose = !isset($parent_elements[$token->name]);
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}
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if ($autoclose && $definition->info[$token->name]->wrap) {
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// Check if an element can be wrapped by another
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// element to make it valid in a context (for
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// example, <ul><ul> needs a <li> in between)
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$wrapname = $definition->info[$token->name]->wrap;
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$wrapdef = $definition->info[$wrapname];
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$elements = $wrapdef->child->getAllowedElements($config);
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if (isset($elements[$token->name]) && isset($parent_elements[$wrapname])) {
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$newtoken = new HTMLPurifier_Token_Start($wrapname);
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$token = $this->insertBefore($newtoken);
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$reprocess = true;
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continue;
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}
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}
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$carryover = false;
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if ($autoclose && $parent_def->formatting) {
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$carryover = true;
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}
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if ($autoclose) {
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// check if this autoclose is doomed to fail
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// (this rechecks $parent, which his harmless)
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$autoclose_ok = isset($global_parent_allowed_elements[$token->name]);
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if (!$autoclose_ok) {
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foreach ($this->stack as $ancestor) {
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$elements = $definition->info[$ancestor->name]->child->getAllowedElements($config);
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if (isset($elements[$token->name])) {
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$autoclose_ok = true;
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break;
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}
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if ($definition->info[$token->name]->wrap) {
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$wrapname = $definition->info[$token->name]->wrap;
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$wrapdef = $definition->info[$wrapname];
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$wrap_elements = $wrapdef->child->getAllowedElements($config);
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if (isset($wrap_elements[$token->name]) && isset($elements[$wrapname])) {
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$autoclose_ok = true;
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break;
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}
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}
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}
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}
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if ($autoclose_ok) {
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// errors need to be updated
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$new_token = new HTMLPurifier_Token_End($parent->name);
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$new_token->start = $parent;
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// [TagClosedSuppress]
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if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
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if (!$carryover) {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
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} else {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
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}
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}
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if ($carryover) {
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$element = clone $parent;
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// [TagClosedAuto]
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$element->armor['MakeWellFormed_TagClosedError'] = true;
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$element->carryover = true;
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$token = $this->processToken(array($new_token, $token, $element));
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} else {
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$token = $this->insertBefore($new_token);
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}
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} else {
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$token = $this->remove();
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}
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$reprocess = true;
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continue;
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}
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}
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$ok = true;
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}
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if ($ok) {
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foreach ($this->injectors as $i => $injector) {
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if (isset($token->skip[$i])) {
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// See Note [Injector skips]
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continue;
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}
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if ($token->rewind !== null && $token->rewind !== $i) {
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continue;
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}
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$r = $token;
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$injector->handleElement($r);
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$token = $this->processToken($r, $i);
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$reprocess = true;
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break;
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}
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if (!$reprocess) {
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// ah, nothing interesting happened; do normal processing
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if ($token instanceof HTMLPurifier_Token_Start) {
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$this->stack[] = $token;
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} elseif ($token instanceof HTMLPurifier_Token_End) {
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throw new HTMLPurifier_Exception(
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'Improper handling of end tag in start code; possible error in MakeWellFormed'
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);
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}
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}
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continue;
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}
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// sanity check: we should be dealing with a closing tag
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if (!$token instanceof HTMLPurifier_Token_End) {
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throw new HTMLPurifier_Exception('Unaccounted for tag token in input stream, bug in HTML Purifier');
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}
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// make sure that we have something open
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if (empty($this->stack)) {
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if ($escape_invalid_tags) {
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if ($e) {
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$e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
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}
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$token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
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} else {
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if ($e) {
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$e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
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}
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$token = $this->remove();
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}
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$reprocess = true;
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continue;
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}
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// first, check for the simplest case: everything closes neatly.
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// Eventually, everything passes through here; if there are problems
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// we modify the input stream accordingly and then punt, so that
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// the tokens get processed again.
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$current_parent = array_pop($this->stack);
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if ($current_parent->name == $token->name) {
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$token->start = $current_parent;
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foreach ($this->injectors as $i => $injector) {
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if (isset($token->skip[$i])) {
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// See Note [Injector skips]
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continue;
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}
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if ($token->rewind !== null && $token->rewind !== $i) {
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continue;
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}
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$r = $token;
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$injector->handleEnd($r);
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$token = $this->processToken($r, $i);
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$this->stack[] = $current_parent;
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$reprocess = true;
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break;
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}
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continue;
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}
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// okay, so we're trying to close the wrong tag
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// undo the pop previous pop
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$this->stack[] = $current_parent;
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// scroll back the entire nest, trying to find our tag.
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// (feature could be to specify how far you'd like to go)
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$size = count($this->stack);
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// -2 because -1 is the last element, but we already checked that
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$skipped_tags = false;
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for ($j = $size - 2; $j >= 0; $j--) {
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if ($this->stack[$j]->name == $token->name) {
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$skipped_tags = array_slice($this->stack, $j);
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break;
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}
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}
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// we didn't find the tag, so remove
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if ($skipped_tags === false) {
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if ($escape_invalid_tags) {
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if ($e) {
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$e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
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}
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$token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
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} else {
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if ($e) {
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$e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
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}
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$token = $this->remove();
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}
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$reprocess = true;
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continue;
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}
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// do errors, in REVERSE $j order: a,b,c with </a></b></c>
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$c = count($skipped_tags);
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if ($e) {
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for ($j = $c - 1; $j > 0; $j--) {
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// notice we exclude $j == 0, i.e. the current ending tag, from
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// the errors... [TagClosedSuppress]
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if (!isset($skipped_tags[$j]->armor['MakeWellFormed_TagClosedError'])) {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by element end', $skipped_tags[$j]);
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}
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}
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}
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// insert tags, in FORWARD $j order: c,b,a with </a></b></c>
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$replace = array($token);
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for ($j = 1; $j < $c; $j++) {
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// ...as well as from the insertions
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$new_token = new HTMLPurifier_Token_End($skipped_tags[$j]->name);
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$new_token->start = $skipped_tags[$j];
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array_unshift($replace, $new_token);
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if (isset($definition->info[$new_token->name]) && $definition->info[$new_token->name]->formatting) {
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// [TagClosedAuto]
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$element = clone $skipped_tags[$j];
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$element->carryover = true;
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$element->armor['MakeWellFormed_TagClosedError'] = true;
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$replace[] = $element;
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}
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}
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$token = $this->processToken($replace);
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$reprocess = true;
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continue;
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}
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$context->destroy('CurrentToken');
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$context->destroy('CurrentNesting');
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$context->destroy('InputZipper');
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unset($this->injectors, $this->stack, $this->tokens);
|
|
return $zipper->toArray($token);
|
|
}
|
|
|
|
/**
|
|
* Processes arbitrary token values for complicated substitution patterns.
|
|
* In general:
|
|
*
|
|
* If $token is an array, it is a list of tokens to substitute for the
|
|
* current token. These tokens then get individually processed. If there
|
|
* is a leading integer in the list, that integer determines how many
|
|
* tokens from the stream should be removed.
|
|
*
|
|
* If $token is a regular token, it is swapped with the current token.
|
|
*
|
|
* If $token is false, the current token is deleted.
|
|
*
|
|
* If $token is an integer, that number of tokens (with the first token
|
|
* being the current one) will be deleted.
|
|
*
|
|
* @param HTMLPurifier_Token|array|int|bool $token Token substitution value
|
|
* @param HTMLPurifier_Injector|int $injector Injector that performed the substitution; default is if
|
|
* this is not an injector related operation.
|
|
* @throws HTMLPurifier_Exception
|
|
*/
|
|
protected function processToken($token, $injector = -1)
|
|
{
|
|
// Zend OpCache miscompiles $token = array($token), so
|
|
// avoid this pattern. See: https://github.com/ezyang/htmlpurifier/issues/108
|
|
|
|
// normalize forms of token
|
|
if (is_object($token)) {
|
|
$tmp = $token;
|
|
$token = array(1, $tmp);
|
|
}
|
|
if (is_int($token)) {
|
|
$tmp = $token;
|
|
$token = array($tmp);
|
|
}
|
|
if ($token === false) {
|
|
$token = array(1);
|
|
}
|
|
if (!is_array($token)) {
|
|
throw new HTMLPurifier_Exception('Invalid token type from injector');
|
|
}
|
|
if (!is_int($token[0])) {
|
|
array_unshift($token, 1);
|
|
}
|
|
if ($token[0] === 0) {
|
|
throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
|
|
}
|
|
|
|
// $token is now an array with the following form:
|
|
// array(number nodes to delete, new node 1, new node 2, ...)
|
|
|
|
$delete = array_shift($token);
|
|
list($old, $r) = $this->zipper->splice($this->token, $delete, $token);
|
|
|
|
if ($injector > -1) {
|
|
// See Note [Injector skips]
|
|
// Determine appropriate skips. Here's what the code does:
|
|
// *If* we deleted one or more tokens, copy the skips
|
|
// of those tokens into the skips of the new tokens (in $token).
|
|
// Also, mark the newly inserted tokens as having come from
|
|
// $injector.
|
|
$oldskip = isset($old[0]) ? $old[0]->skip : array();
|
|
foreach ($token as $object) {
|
|
$object->skip = $oldskip;
|
|
$object->skip[$injector] = true;
|
|
}
|
|
}
|
|
|
|
return $r;
|
|
|
|
}
|
|
|
|
/**
|
|
* Inserts a token before the current token. Cursor now points to
|
|
* this token. You must reprocess after this.
|
|
* @param HTMLPurifier_Token $token
|
|
*/
|
|
private function insertBefore($token)
|
|
{
|
|
// NB not $this->zipper->insertBefore(), due to positioning
|
|
// differences
|
|
$splice = $this->zipper->splice($this->token, 0, array($token));
|
|
|
|
return $splice[1];
|
|
}
|
|
|
|
/**
|
|
* Removes current token. Cursor now points to new token occupying previously
|
|
* occupied space. You must reprocess after this.
|
|
*/
|
|
private function remove()
|
|
{
|
|
return $this->zipper->delete();
|
|
}
|
|
}
|
|
|
|
// Note [Injector skips]
|
|
// ~~~~~~~~~~~~~~~~~~~~~
|
|
// When I originally designed this class, the idea behind the 'skip'
|
|
// property of HTMLPurifier_Token was to help avoid infinite loops
|
|
// in injector processing. For example, suppose you wrote an injector
|
|
// that bolded swear words. Naively, you might write it so that
|
|
// whenever you saw ****, you replaced it with <strong>****</strong>.
|
|
//
|
|
// When this happens, we will reprocess all of the tokens with the
|
|
// other injectors. Now there is an opportunity for infinite loop:
|
|
// if we rerun the swear-word injector on these tokens, we might
|
|
// see **** and then reprocess again to get
|
|
// <strong><strong>****</strong></strong> ad infinitum.
|
|
//
|
|
// Thus, the idea of a skip is that once we process a token with
|
|
// an injector, we mark all of those tokens as having "come from"
|
|
// the injector, and we never run the injector again on these
|
|
// tokens.
|
|
//
|
|
// There were two more complications, however:
|
|
//
|
|
// - With HTMLPurifier_Injector_RemoveEmpty, we noticed that if
|
|
// you had <b><i></i></b>, after you removed the <i></i>, you
|
|
// really would like this injector to go back and reprocess
|
|
// the <b> tag, discovering that it is now empty and can be
|
|
// removed. So we reintroduced the possibility of infinite looping
|
|
// by adding a "rewind" function, which let you go back to an
|
|
// earlier point in the token stream and reprocess it with injectors.
|
|
// Needless to say, we need to UN-skip the token so it gets
|
|
// reprocessed.
|
|
//
|
|
// - Suppose that you successfuly process a token, replace it with
|
|
// one with your skip mark, but now another injector wants to
|
|
// process the skipped token with another token. Should you continue
|
|
// to skip that new token, or reprocess it? If you reprocess,
|
|
// you can end up with an infinite loop where one injector converts
|
|
// <a> to <b>, and then another injector converts it back. So
|
|
// we inherit the skips, but for some reason, I thought that we
|
|
// should inherit the skip from the first token of the token
|
|
// that we deleted. Why? Well, it seems to work OK.
|
|
//
|
|
// If I were to redesign this functionality, I would absolutely not
|
|
// go about doing it this way: the semantics are just not very well
|
|
// defined, and in any case you probably wanted to operate on trees,
|
|
// not token streams.
|
|
|
|
// vim: et sw=4 sts=4
|