root/Source/wtf/text/TextEncodingRegistry.cpp

DEFINITIONS

1. encodingRegistryMutex
2. checkExistingName
3. checkExistingName
4. isUndesiredAlias
5. addToTextEncodingNameMap
6. addToTextCodecMap
7. pruneBlacklistedCodecs
8. buildBaseTextCodecMaps
9. addEncodingName
10. buildQuirksSets
11. isJapaneseEncoding
12. shouldShowBackslashAsCurrencySymbolIn
13. extendTextCodecMaps
14. newTextCodec
15. atomicCanonicalTextEncodingName
16. atomicCanonicalTextEncodingName
17. atomicCanonicalTextEncodingName
18. noExtendedTextEncodingNameUsed
19. dumpTextEncodingNameMap

/*
 * Copyright (C) 2006, 2007, 2011 Apple Inc. All rights reserved.
 * Copyright (C) 2007-2009 Torch Mobile, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "wtf/text/TextEncodingRegistry.h"

#include "wtf/ASCIICType.h"
#include "wtf/CurrentTime.h"
#include "wtf/HashMap.h"
#include "wtf/HashSet.h"
#include "wtf/MainThread.h"
#include "wtf/StdLibExtras.h"
#include "wtf/StringExtras.h"
#include "wtf/ThreadingPrimitives.h"
#include "wtf/text/CString.h"
#include "wtf/text/TextCodecICU.h"
#include "wtf/text/TextCodecLatin1.h"
#include "wtf/text/TextCodecUTF16.h"
#include "wtf/text/TextCodecUTF8.h"
#include "wtf/text/TextCodecUserDefined.h"
#include "wtf/text/TextEncoding.h"

namespace WTF {

const size_t maxEncodingNameLength = 63;

// Hash for all-ASCII strings that does case folding.
struct TextEncodingNameHash {
    static bool equal(const char* s1, const char* s2)
    {
        char c1;
        char c2;
        do {
#if defined(_MSC_FULL_VER) && _MSC_FULL_VER == 170051106
            // Workaround for a bug in the VS2012 Update 1 optimizer, remove once the fix is released.
            // https://connect.microsoft.com/VisualStudio/feedback/details/777533/vs2012-c-optimizing-bug-when-using-inline-and-char-return-type-x86-target-only
            c1 = toASCIILower(*s1++);
            c2 = toASCIILower(*s2++);
            if (c1 != c2)
                return false;
#else
            c1 = *s1++;
            c2 = *s2++;
            if (toASCIILower(c1) != toASCIILower(c2))
                return false;
#endif
        } while (c1 && c2);
        return !c1 && !c2;
    }

    // This algorithm is the one-at-a-time hash from:
    // http://burtleburtle.net/bob/hash/hashfaq.html
    // http://burtleburtle.net/bob/hash/doobs.html
    static unsigned hash(const char* s)
    {
        unsigned h = WTF::stringHashingStartValue;
        for (;;) {
            char c = *s++;
            if (!c) {
                h += (h << 3);
                h ^= (h >> 11);
                h += (h << 15);
                return h;
            }
            h += toASCIILower(c);
            h += (h << 10);
            h ^= (h >> 6);
        }
    }

    static const bool safeToCompareToEmptyOrDeleted = false;
};

struct TextCodecFactory {
    NewTextCodecFunction function;
    const void* additionalData;
    TextCodecFactory(NewTextCodecFunction f = 0, const void* d = 0) : function(f), additionalData(d) { }
};

typedef HashMap<const char*, const char*, TextEncodingNameHash> TextEncodingNameMap;
typedef HashMap<const char*, TextCodecFactory> TextCodecMap;

static Mutex& encodingRegistryMutex()
{
    // We don't have to use AtomicallyInitializedStatic here because
    // this function is called on the main thread for any page before
    // it is used in worker threads.
    DEFINE_STATIC_LOCAL(Mutex, mutex, ());
    return mutex;
}

static TextEncodingNameMap* textEncodingNameMap;
static TextCodecMap* textCodecMap;
static bool didExtendTextCodecMaps;
static HashSet<const char*>* japaneseEncodings;
static HashSet<const char*>* nonBackslashEncodings;

static const char textEncodingNameBlacklist[][6] = { "UTF-7" };

#if ERROR_DISABLED

static inline void checkExistingName(const char*, const char*) { }

#else

static void checkExistingName(const char* alias, const char* atomicName)
{
    const char* oldAtomicName = textEncodingNameMap->get(alias);
    if (!oldAtomicName)
        return;
    if (oldAtomicName == atomicName)
        return;
    // Keep the warning silent about one case where we know this will happen.
    if (strcmp(alias, "ISO-8859-8-I") == 0
            && strcmp(oldAtomicName, "ISO-8859-8-I") == 0
            && strcasecmp(atomicName, "iso-8859-8") == 0)
        return;
    WTF_LOG_ERROR("alias %s maps to %s already, but someone is trying to make it map to %s", alias, oldAtomicName, atomicName);
}

#endif

static bool isUndesiredAlias(const char* alias)
{
    // Reject aliases with version numbers that are supported by some back-ends (such as "ISO_2022,locale=ja,version=0" in ICU).
    for (const char* p = alias; *p; ++p) {
        if (*p == ',')
            return true;
    }
    // 8859_1 is known to (at least) ICU, but other browsers don't support this name - and having it caused a compatibility
    // problem, see bug 43554.
    if (0 == strcmp(alias, "8859_1"))
        return true;
    return false;
}

static void addToTextEncodingNameMap(const char* alias, const char* name)
{
    ASSERT(strlen(alias) <= maxEncodingNameLength);
    if (isUndesiredAlias(alias))
        return;
    const char* atomicName = textEncodingNameMap->get(name);
    ASSERT(strcmp(alias, name) == 0 || atomicName);
    if (!atomicName)
        atomicName = name;
    checkExistingName(alias, atomicName);
    textEncodingNameMap->add(alias, atomicName);
}

static void addToTextCodecMap(const char* name, NewTextCodecFunction function, const void* additionalData)
{
    const char* atomicName = textEncodingNameMap->get(name);
    ASSERT(atomicName);
    textCodecMap->add(atomicName, TextCodecFactory(function, additionalData));
}

static void pruneBlacklistedCodecs()
{
    for (size_t i = 0; i < WTF_ARRAY_LENGTH(textEncodingNameBlacklist); ++i) {
        const char* atomicName = textEncodingNameMap->get(textEncodingNameBlacklist[i]);
        if (!atomicName)
            continue;

        Vector<const char*> names;
        TextEncodingNameMap::const_iterator it = textEncodingNameMap->begin();
        TextEncodingNameMap::const_iterator end = textEncodingNameMap->end();
        for (; it != end; ++it) {
            if (it->value == atomicName)
                names.append(it->key);
        }

        size_t length = names.size();
        for (size_t j = 0; j < length; ++j)
            textEncodingNameMap->remove(names[j]);

        textCodecMap->remove(atomicName);
    }
}

static void buildBaseTextCodecMaps()
{
    ASSERT(isMainThread());
    ASSERT(!textCodecMap);
    ASSERT(!textEncodingNameMap);

    textCodecMap = new TextCodecMap;
    textEncodingNameMap = new TextEncodingNameMap;

    TextCodecLatin1::registerEncodingNames(addToTextEncodingNameMap);
    TextCodecLatin1::registerCodecs(addToTextCodecMap);

    TextCodecUTF8::registerEncodingNames(addToTextEncodingNameMap);
    TextCodecUTF8::registerCodecs(addToTextCodecMap);

    TextCodecUTF16::registerEncodingNames(addToTextEncodingNameMap);
    TextCodecUTF16::registerCodecs(addToTextCodecMap);

    TextCodecUserDefined::registerEncodingNames(addToTextEncodingNameMap);
    TextCodecUserDefined::registerCodecs(addToTextCodecMap);
}

static void addEncodingName(HashSet<const char*>* set, const char* name)
{
    // We must not use atomicCanonicalTextEncodingName() because this function is called in it.
    const char* atomicName = textEncodingNameMap->get(name);
    if (atomicName)
        set->add(atomicName);
}

static void buildQuirksSets()
{
    // FIXME: Having isJapaneseEncoding() and shouldShowBackslashAsCurrencySymbolIn()
    // and initializing the sets for them in TextEncodingRegistry.cpp look strange.

    ASSERT(!japaneseEncodings);
    ASSERT(!nonBackslashEncodings);

    japaneseEncodings = new HashSet<const char*>;
    addEncodingName(japaneseEncodings, "EUC-JP");
    addEncodingName(japaneseEncodings, "ISO-2022-JP");
    addEncodingName(japaneseEncodings, "ISO-2022-JP-1");
    addEncodingName(japaneseEncodings, "ISO-2022-JP-2");
    addEncodingName(japaneseEncodings, "ISO-2022-JP-3");
    addEncodingName(japaneseEncodings, "JIS_C6226-1978");
    addEncodingName(japaneseEncodings, "JIS_X0201");
    addEncodingName(japaneseEncodings, "JIS_X0208-1983");
    addEncodingName(japaneseEncodings, "JIS_X0208-1990");
    addEncodingName(japaneseEncodings, "JIS_X0212-1990");
    addEncodingName(japaneseEncodings, "Shift_JIS");
    addEncodingName(japaneseEncodings, "Shift_JIS_X0213-2000");
    addEncodingName(japaneseEncodings, "cp932");
    addEncodingName(japaneseEncodings, "x-mac-japanese");

    nonBackslashEncodings = new HashSet<const char*>;
    // The text encodings below treat backslash as a currency symbol for IE compatibility.
    // See http://blogs.msdn.com/michkap/archive/2005/09/17/469941.aspx for more information.
    addEncodingName(nonBackslashEncodings, "x-mac-japanese");
    addEncodingName(nonBackslashEncodings, "ISO-2022-JP");
    addEncodingName(nonBackslashEncodings, "EUC-JP");
    // Shift_JIS_X0213-2000 is not the same encoding as Shift_JIS on Mac. We need to register both of them.
    addEncodingName(nonBackslashEncodings, "Shift_JIS");
    addEncodingName(nonBackslashEncodings, "Shift_JIS_X0213-2000");
}

bool isJapaneseEncoding(const char* canonicalEncodingName)
{
    return canonicalEncodingName && japaneseEncodings && japaneseEncodings->contains(canonicalEncodingName);
}

bool shouldShowBackslashAsCurrencySymbolIn(const char* canonicalEncodingName)
{
    return canonicalEncodingName && nonBackslashEncodings && nonBackslashEncodings->contains(canonicalEncodingName);
}

static void extendTextCodecMaps()
{
    TextCodecICU::registerEncodingNames(addToTextEncodingNameMap);
    TextCodecICU::registerCodecs(addToTextCodecMap);

    pruneBlacklistedCodecs();
    buildQuirksSets();
}

PassOwnPtr<TextCodec> newTextCodec(const TextEncoding& encoding)
{
    MutexLocker lock(encodingRegistryMutex());

    ASSERT(textCodecMap);
    TextCodecFactory factory = textCodecMap->get(encoding.name());
    ASSERT(factory.function);
    return factory.function(encoding, factory.additionalData);
}

const char* atomicCanonicalTextEncodingName(const char* name)
{
    if (!name || !name[0])
        return 0;
    if (!textEncodingNameMap)
        buildBaseTextCodecMaps();

    MutexLocker lock(encodingRegistryMutex());

    if (const char* atomicName = textEncodingNameMap->get(name))
        return atomicName;
    if (didExtendTextCodecMaps)
        return 0;
    extendTextCodecMaps();
    didExtendTextCodecMaps = true;
    return textEncodingNameMap->get(name);
}

template <typename CharacterType>
const char* atomicCanonicalTextEncodingName(const CharacterType* characters, size_t length)
{
    char buffer[maxEncodingNameLength + 1];
    size_t j = 0;
    for (size_t i = 0; i < length; ++i) {
        CharacterType c = characters[i];
        if (j == maxEncodingNameLength)
            return 0;
        buffer[j++] = c;
    }
    buffer[j] = 0;
    return atomicCanonicalTextEncodingName(buffer);
}

const char* atomicCanonicalTextEncodingName(const String& alias)
{
    if (!alias.length())
        return 0;

    if (alias.is8Bit())
        return atomicCanonicalTextEncodingName<LChar>(alias.characters8(), alias.length());

    return atomicCanonicalTextEncodingName<UChar>(alias.characters16(), alias.length());
}

bool noExtendedTextEncodingNameUsed()
{
    // If the calling thread did not use extended encoding names, it is fine for it to use a stale false value.
    return !didExtendTextCodecMaps;
}

#ifndef NDEBUG
void dumpTextEncodingNameMap()
{
    unsigned size = textEncodingNameMap->size();
    fprintf(stderr, "Dumping %u entries in WTF::TextEncodingNameMap...\n", size);

    MutexLocker lock(encodingRegistryMutex());

    TextEncodingNameMap::const_iterator it = textEncodingNameMap->begin();
    TextEncodingNameMap::const_iterator end = textEncodingNameMap->end();
    for (; it != end; ++it)
        fprintf(stderr, "'%s' => '%s'\n", it->key, it->value);
}
#endif

} // namespace WTF