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      1 /*
      2  * Copyright (C) 2010 Google Inc. All Rights Reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #include "config.h"
     27 #include "core/html/parser/HTMLMetaCharsetParser.h"
     28 
     29 #include "core/HTMLNames.h"
     30 #include "core/html/parser/HTMLParserIdioms.h"
     31 #include "core/html/parser/HTMLParserOptions.h"
     32 #include "core/html/parser/HTMLTokenizer.h"
     33 #include "wtf/text/TextEncodingRegistry.h"
     34 #include "wtf/text/WTFString.h"
     35 
     36 using namespace WTF;
     37 
     38 namespace WebCore {
     39 
     40 using namespace HTMLNames;
     41 
     42 HTMLMetaCharsetParser::HTMLMetaCharsetParser()
     43     : m_tokenizer(HTMLTokenizer::create(HTMLParserOptions(0)))
     44     , m_assumedCodec(newTextCodec(Latin1Encoding()))
     45     , m_inHeadSection(true)
     46     , m_doneChecking(false)
     47 {
     48 }
     49 
     50 HTMLMetaCharsetParser::~HTMLMetaCharsetParser()
     51 {
     52 }
     53 
     54 bool HTMLMetaCharsetParser::processMeta()
     55 {
     56     const HTMLToken::AttributeList& tokenAttributes = m_token.attributes();
     57     HTMLAttributeList attributes;
     58     for (HTMLToken::AttributeList::const_iterator iter = tokenAttributes.begin(); iter != tokenAttributes.end(); ++iter) {
     59         String attributeName = attemptStaticStringCreation(iter->name, Likely8Bit);
     60         String attributeValue = StringImpl::create8BitIfPossible(iter->value);
     61         attributes.append(std::make_pair(attributeName, attributeValue));
     62     }
     63 
     64     m_encoding = encodingFromMetaAttributes(attributes);
     65     return m_encoding.isValid();
     66 }
     67 
     68 static const int bytesToCheckUnconditionally = 1024; // That many input bytes will be checked for meta charset even if <head> section is over.
     69 
     70 bool HTMLMetaCharsetParser::checkForMetaCharset(const char* data, size_t length)
     71 {
     72     if (m_doneChecking)
     73         return true;
     74 
     75     ASSERT(!m_encoding.isValid());
     76 
     77     // We still don't have an encoding, and are in the head.
     78     // The following tags are allowed in <head>:
     79     // SCRIPT|STYLE|META|LINK|OBJECT|TITLE|BASE
     80 
     81     // We stop scanning when a tag that is not permitted in <head>
     82     // is seen, rather when </head> is seen, because that more closely
     83     // matches behavior in other browsers; more details in
     84     // <http://bugs.webkit.org/show_bug.cgi?id=3590>.
     85 
     86     // Additionally, we ignore things that looks like tags in <title>, <script>
     87     // and <noscript>; see <http://bugs.webkit.org/show_bug.cgi?id=4560>,
     88     // <http://bugs.webkit.org/show_bug.cgi?id=12165> and
     89     // <http://bugs.webkit.org/show_bug.cgi?id=12389>.
     90 
     91     // Since many sites have charset declarations after <body> or other tags
     92     // that are disallowed in <head>, we don't bail out until we've checked at
     93     // least bytesToCheckUnconditionally bytes of input.
     94 
     95     m_input.append(SegmentedString(m_assumedCodec->decode(data, length)));
     96 
     97     while (m_tokenizer->nextToken(m_input, m_token)) {
     98         bool end = m_token.type() == HTMLToken::EndTag;
     99         if (end || m_token.type() == HTMLToken::StartTag) {
    100             String tagName = attemptStaticStringCreation(m_token.name(), Likely8Bit);
    101             if (!end) {
    102                 m_tokenizer->updateStateFor(tagName);
    103                 if (threadSafeMatch(tagName, metaTag) && processMeta()) {
    104                     m_doneChecking = true;
    105                     return true;
    106                 }
    107             }
    108 
    109             if (!threadSafeMatch(tagName, scriptTag) && !threadSafeMatch(tagName, noscriptTag)
    110                 && !threadSafeMatch(tagName, styleTag) && !threadSafeMatch(tagName, linkTag)
    111                 && !threadSafeMatch(tagName, metaTag) && !threadSafeMatch(tagName, objectTag)
    112                 && !threadSafeMatch(tagName, titleTag) && !threadSafeMatch(tagName, baseTag)
    113                 && (end || !threadSafeMatch(tagName, htmlTag)) && (end || !threadSafeMatch(tagName, headTag))) {
    114                 m_inHeadSection = false;
    115             }
    116         }
    117 
    118         if (!m_inHeadSection && m_input.numberOfCharactersConsumed() >= bytesToCheckUnconditionally) {
    119             m_doneChecking = true;
    120             return true;
    121         }
    122 
    123         m_token.clear();
    124     }
    125 
    126     return false;
    127 }
    128 
    129 }
    130