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#include <qplatformdefs.h> // always first

#include "mimedatabase.h"

#include "mimedatabase_p.h"

#include "mimemagicrule_p.h"
#include "mimeprovider_p.h"
#include "mimetype_p.h"

#include <QtCore/QCoreApplication>
#include <QtCore/QFile>
#include <QtCore/QFileInfo>
#include <QtCore/QSet>
#include <QtCore/QBuffer>
#include <QtCore/QUrl>
#include <QtCore/QStack>
#include <QtCore/QDebug>

#include <algorithm>
#include <functional>

static const char ALL_FILES_FILTER[]      = QT_TRANSLATE_NOOP("Core", "All Files (*)");

using namespace Utils;
using namespace Utils::Internal;

Q_GLOBAL_STATIC(MimeDatabasePrivate, staticMimeDatabase)

MimeDatabasePrivate *MimeDatabasePrivate::instance()
{
    return staticMimeDatabase();
}

MimeDatabasePrivate::MimeDatabasePrivate()
    : m_provider(0), m_defaultMimeType(QLatin1String("application/octet-stream"))
{
}

MimeDatabasePrivate::~MimeDatabasePrivate()
{
    delete m_provider;
    m_provider = 0;
}

MimeProviderBase *MimeDatabasePrivate::provider()
{
    if (!m_provider) {
//        MimeProviderBase *binaryProvider = new MimeBinaryProvider(this);
//        if (binaryProvider->isValid()) {
//            m_provider = binaryProvider;
//        } else {
//            delete binaryProvider;
        m_provider = new MimeXMLProvider(this);
//        }
    }
    return m_provider;
}

void MimeDatabasePrivate::setProvider(MimeProviderBase *theProvider)
{
    delete m_provider;
    m_provider = theProvider;
}

/*!
    \internal
    Returns a MIME type or an invalid one if none found
 */
MimeType MimeDatabasePrivate::mimeTypeForName(const QString &nameOrAlias)
{
    return provider()->mimeTypeForName(provider()->resolveAlias(nameOrAlias));
}

QStringList MimeDatabasePrivate::mimeTypeForFileName(const QString &fileName, QString *foundSuffix)
{
    if (fileName.endsWith(QLatin1Char('/')))
        return QStringList() << QLatin1String("inode/directory");

    const QStringList matchingMimeTypes = provider()->findByFileName(QFileInfo(fileName).fileName(), foundSuffix);
    return matchingMimeTypes;
}

static inline bool isTextFile(const QByteArray &data)
{
    // UTF16 byte order marks
    static const char bigEndianBOM[] = "\xFE\xFF";
    static const char littleEndianBOM[] = "\xFF\xFE";
    if (data.startsWith(bigEndianBOM) || data.startsWith(littleEndianBOM))
        return true;

    // Check the first 32 bytes (see shared-mime spec)
    const char *p = data.constData();
    const char *e = p + qMin(32, data.size());
    for ( ; p < e; ++p) {
        if ((unsigned char)(*p) < 32 && *p != 9 && *p !=10 && *p != 13)
            return false;
    }

    return true;
}

MimeType MimeDatabasePrivate::findByData(const QByteArray &data, int *accuracyPtr)
{
//    if (data.isEmpty()) {
//        *accuracyPtr = 100;
//        return mimeTypeForName(QLatin1String("application/x-zerosize"));
//    }

    *accuracyPtr = 0;
    MimeType candidate = provider()->findByMagic(data, accuracyPtr);

    if (candidate.isValid())
        return candidate;

    if (isTextFile(data)) {
        *accuracyPtr = 5;
        return mimeTypeForName(QLatin1String("text/plain"));
    }

    return mimeTypeForName(defaultMimeType());
}

MimeType MimeDatabasePrivate::mimeTypeForFileNameAndData(const QString &fileName, QIODevice *device, int *accuracyPtr)
{
    // First, glob patterns are evaluated. If there is a match with max weight,
    // this one is selected and we are done. Otherwise, the file contents are
    // evaluated and the match with the highest value (either a magic priority or
    // a glob pattern weight) is selected. Matching starts from max level (most
    // specific) in both cases, even when there is already a suffix matching candidate.
    *accuracyPtr = 0;

    // Pass 1) Try to match on the file name
    QStringList candidatesByName = mimeTypeForFileName(fileName);
    if (candidatesByName.count() == 1) {
        *accuracyPtr = 100;
        const MimeType mime = mimeTypeForName(candidatesByName.at(0));
        if (mime.isValid())
            return mime;
        candidatesByName.clear();
    }

    // Extension is unknown, or matches multiple mimetypes.
    // Pass 2) Match on content, if we can read the data
    const bool openedByUs = !device->isOpen() && device->open(QIODevice::ReadOnly);
    if (device->isOpen()) {

        // Read 16K in one go (QIODEVICE_BUFFERSIZE in qiodevice_p.h).
        // This is much faster than seeking back and forth into QIODevice.
        const QByteArray data = device->peek(16384);

        if (openedByUs)
            device->close();

        int magicAccuracy = 0;
        MimeType candidateByData(findByData(data, &magicAccuracy));

        // Disambiguate conflicting extensions (if magic matching found something)
        if (candidateByData.isValid() && magicAccuracy > 0) {
            const QString sniffedMime = candidateByData.name();
            // If the sniffedMime matches a glob match, use it
            if (candidatesByName.contains(sniffedMime)) {
                *accuracyPtr = 100;
                return candidateByData;
            }
            // If there is a glob match that is a sub class of sniffedMime, use it
            foreach (const QString &m, candidatesByName) {
                if (inherits(m, sniffedMime)) {
                    // We have magic + pattern pointing to this, so it's a pretty good match
                    *accuracyPtr = 100;
                    return mimeTypeForName(m);
                }
            }
            *accuracyPtr = magicAccuracy;
            return candidateByData;
        }
    }

    if (candidatesByName.count() > 1) {
        *accuracyPtr = 20;
        candidatesByName.sort(); // to make it deterministic
        const MimeType mime = mimeTypeForName(candidatesByName.at(0));
        if (mime.isValid())
            return mime;
    }

    return mimeTypeForName(defaultMimeType());
}

QList<MimeType> MimeDatabasePrivate::allMimeTypes()
{
    return provider()->allMimeTypes();
}

bool MimeDatabasePrivate::inherits(const QString &mime, const QString &parent)
{
    const QString resolvedParent = provider()->resolveAlias(parent);
    //Q_ASSERT(provider()->resolveAlias(mime) == mime);
    QStack<QString> toCheck;
    QSet<QString> seen; // avoid endless loop on bogus mime data
    toCheck.push(mime);
    seen.insert(mime);
    while (!toCheck.isEmpty()) {
        const QString current = toCheck.pop();
        if (current == resolvedParent)
            return true;
        foreach (const QString &par, provider()->parents(current)) {
            int seenSize = seen.size();
            seen.insert(par);
            if (seen.size() != seenSize) // haven't seen before, so add
                toCheck.push(par);
        }
    }
    return false;
}

/*!
    \class MimeDatabase
    \inmodule QtCore
    \brief The MimeDatabase class maintains a database of MIME types.

    \since 5.0

    The MIME type database is provided by the freedesktop.org shared-mime-info
    project. If the MIME type database cannot be found on the system, as is the case
    on most Windows and Mac OS X systems, Qt will use its own copy of it.

    Applications which want to define custom MIME types need to install an
    XML file into the locations searched for MIME definitions.
    These locations can be queried with
    \code
    QStandardPaths::locateAll(QStandardPaths::GenericDataLocation, QLatin1String("mime/packages"),
                              QStandardPaths::LocateDirectory);
    \endcode
    On a typical Unix system, this will be /usr/share/mime/packages/, but it is also
    possible to extend the list of directories by setting the environment variable
    \c XDG_DATA_DIRS. For instance adding /opt/myapp/share to \c XDG_DATA_DIRS will result
    in /opt/myapp/share/mime/packages/ being searched for MIME definitions.

    Here is an example of MIME XML:
    \code
    <?xml version="1.0" encoding="UTF-8"?>
    <mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
      <mime-type type="application/vnd.nokia.qt.qmakeprofile">
        <comment xml:lang="en">Qt qmake Profile</comment>
        <glob pattern="*.pro" weight="50"/>
      </mime-type>
    </mime-info>
    \endcode

    For more details about the syntax of XML MIME definitions, including defining
    "magic" in order to detect MIME types based on data as well, read the
    Shared Mime Info specification at
    http://standards.freedesktop.org/shared-mime-info-spec/shared-mime-info-spec-latest.html

    On Unix systems, a binary cache is used for more performance. This cache is generated
    by the command "update-mime-database path", where path would be /opt/myapp/share/mime
    in the above example. Make sure to run this command when installing the MIME type
    definition file.

    \threadsafe

    \snippet code/src_corelib_mimetype_qmimedatabase.cpp 0

    \sa MimeType
 */

/*!
    \fn MimeDatabase::MimeDatabase();
    Constructs a MimeDatabase object.

    It is perfectly OK to create an instance of MimeDatabase every time you need to
    perform a lookup.
    The parsing of mimetypes is done on demand (when shared-mime-info is installed)
    or when the very first instance is constructed (when parsing XML files directly).
 */
MimeDatabase::MimeDatabase() :
        d(staticMimeDatabase())
{
}

/*!
    \fn MimeDatabase::~MimeDatabase();
    Destroys the MimeDatabase object.
 */
MimeDatabase::~MimeDatabase()
{
    d = 0;
}

void MimeDatabase::addMimeTypes(const QString &fileName)
{
    auto d = MimeDatabasePrivate::instance();
    QMutexLocker locker(&d->mutex);
    auto xmlProvider = static_cast<MimeXMLProvider *>(d->provider());
    xmlProvider->addFile(fileName);
}

QString MimeDatabase::allFiltersString(QString *allFilesFilter)
{
    MimeDatabase mdb;
    QSet<QString> uniqueFilters;
    foreach (const MimeType &mt, mdb.allMimeTypes()) {
        const QString &filterString = mt.filterString();
        if (!filterString.isEmpty())
            uniqueFilters.insert(mt.filterString());
    }
    QStringList filters;
    foreach (const QString &filter, uniqueFilters)
        filters.append(filter);
    filters.sort();
    static const QString allFiles =
        QCoreApplication::translate("Core", ALL_FILES_FILTER);
    if (allFilesFilter)
        *allFilesFilter = allFiles;

    // Prepend all files filter
    filters.prepend(allFiles);

    return filters.join(QLatin1String(";;"));
}

QStringList MimeDatabase::allGlobPatterns()
{
    MimeDatabase mdb;
    QStringList patterns;
    foreach (const MimeType &mt, mdb.allMimeTypes())
        patterns.append(mt.globPatterns());
    return patterns;
}

/*!
    \fn MimeType MimeDatabase::mimeTypeForName(const QString &nameOrAlias) const;
    Returns a MIME type for \a nameOrAlias or an invalid one if none found.
 */
MimeType MimeDatabase::mimeTypeForName(const QString &nameOrAlias) const
{
    QMutexLocker locker(&d->mutex);

    return d->mimeTypeForName(nameOrAlias);
}

/*!
    Returns a MIME type for \a fileInfo.

    A valid MIME type is always returned.

    The default matching algorithm looks at both the file name and the file
    contents, if necessary. The file extension has priority over the contents,
    but the contents will be used if the file extension is unknown, or
    matches multiple MIME types.
    If \a fileInfo is a Unix symbolic link, the file that it refers to
    will be used instead.
    If the file doesn't match any known pattern or data, the default MIME type
    (application/octet-stream) is returned.

    When \a mode is set to MatchExtension, only the file name is used, not
    the file contents. The file doesn't even have to exist. If the file name
    doesn't match any known pattern, the default MIME type (application/octet-stream)
    is returned.
    If multiple MIME types match this file, the first one (alphabetically) is returned.

    When \a mode is set to MatchContent, and the file is readable, only the
    file contents are used to determine the MIME type. This is equivalent to
    calling mimeTypeForData with a QFile as input device.

    \a fileInfo may refer to an absolute or relative path.

    \sa MimeType::isDefault(), mimeTypeForData()
*/
MimeType MimeDatabase::mimeTypeForFile(const QFileInfo &fileInfo, MatchMode mode) const
{
    QMutexLocker locker(&d->mutex);

    if (fileInfo.isDir())
        return d->mimeTypeForName(QLatin1String("inode/directory"));

    QFile file(fileInfo.absoluteFilePath());

#ifdef Q_OS_UNIX
    // Cannot access statBuf.st_mode from the filesystem engine, so we have to stat again.
    const QByteArray nativeFilePath = QFile::encodeName(file.fileName());
    QT_STATBUF statBuffer;
    if (QT_LSTAT(nativeFilePath.constData(), &statBuffer) == 0) {
        if (S_ISCHR(statBuffer.st_mode))
            return d->mimeTypeForName(QLatin1String("inode/chardevice"));
        if (S_ISBLK(statBuffer.st_mode))
            return d->mimeTypeForName(QLatin1String("inode/blockdevice"));
        if (S_ISFIFO(statBuffer.st_mode))
            return d->mimeTypeForName(QLatin1String("inode/fifo"));
        if (S_ISSOCK(statBuffer.st_mode))
            return d->mimeTypeForName(QLatin1String("inode/socket"));
    }
#endif

    int priority = 0;
    switch (mode) {
    case MatchDefault:
        return d->mimeTypeForFileNameAndData(fileInfo.absoluteFilePath(), &file, &priority);
    case MatchExtension:
        locker.unlock();
        return mimeTypeForFile(fileInfo.absoluteFilePath(), mode);
    case MatchContent:
        if (file.open(QIODevice::ReadOnly)) {
            locker.unlock();
            return mimeTypeForData(&file);
        } else {
            return d->mimeTypeForName(d->defaultMimeType());
        }
    default:
        Q_ASSERT(false);
    }
    return d->mimeTypeForName(d->defaultMimeType());
}

/*!
    Returns a MIME type for the file named \a fileName using \a mode.

    \overload
*/
MimeType MimeDatabase::mimeTypeForFile(const QString &fileName, MatchMode mode) const
{
    if (mode == MatchExtension) {
        QMutexLocker locker(&d->mutex);
        QStringList matches = d->mimeTypeForFileName(fileName);
        const int matchCount = matches.count();
        if (matchCount == 0) {
            return d->mimeTypeForName(d->defaultMimeType());
        } else if (matchCount == 1) {
            return d->mimeTypeForName(matches.first());
        } else {
            // We have to pick one.
            matches.sort(); // Make it deterministic
            return d->mimeTypeForName(matches.first());
        }
    } else {
        // Implemented as a wrapper around mimeTypeForFile(QFileInfo), so no mutex.
        QFileInfo fileInfo(fileName);
        return mimeTypeForFile(fileInfo, mode);
    }
}

/*!
    Returns the MIME types for the file name \a fileName.

    If the file name doesn't match any known pattern, an empty list is returned.
    If multiple MIME types match this file, they are all returned.

    This function does not try to open the file. To also use the content
    when determining the MIME type, use mimeTypeForFile() or
    mimeTypeForFileNameAndData() instead.

    \sa mimeTypeForFile()
*/
QList<MimeType> MimeDatabase::mimeTypesForFileName(const QString &fileName) const
{
    QMutexLocker locker(&d->mutex);

    QStringList matches = d->mimeTypeForFileName(fileName);
    QList<MimeType> mimes;
    matches.sort(); // Make it deterministic
    foreach (const QString &mime, matches)
        mimes.append(d->mimeTypeForName(mime));
    return mimes;
}
/*!
    Returns the suffix for the file \a fileName, as known by the MIME database.

    This allows to pre-select "tar.bz2" for foo.tar.bz2, but still only
    "txt" for my.file.with.dots.txt.
*/
QString MimeDatabase::suffixForFileName(const QString &fileName) const
{
    QMutexLocker locker(&d->mutex);
    QString foundSuffix;
    d->mimeTypeForFileName(fileName, &foundSuffix);
    return foundSuffix;
}

/*!
    Returns a MIME type for \a data.

    A valid MIME type is always returned. If \a data doesn't match any
    known MIME type data, the default MIME type (application/octet-stream)
    is returned.
*/
MimeType MimeDatabase::mimeTypeForData(const QByteArray &data) const
{
    QMutexLocker locker(&d->mutex);

    int accuracy = 0;
    return d->findByData(data, &accuracy);
}

/*!
    Returns a MIME type for the data in \a device.

    A valid MIME type is always returned. If the data in \a device doesn't match any
    known MIME type data, the default MIME type (application/octet-stream)
    is returned.
*/
MimeType MimeDatabase::mimeTypeForData(QIODevice *device) const
{
    QMutexLocker locker(&d->mutex);

    int accuracy = 0;
    const bool openedByUs = !device->isOpen() && device->open(QIODevice::ReadOnly);
    if (device->isOpen()) {
        // Read 16K in one go (QIODEVICE_BUFFERSIZE in qiodevice_p.h).
        // This is much faster than seeking back and forth into QIODevice.
        const QByteArray data = device->peek(16384);
        const MimeType result = d->findByData(data, &accuracy);
        if (openedByUs)
            device->close();
        return result;
    }
    return d->mimeTypeForName(d->defaultMimeType());
}

/*!
    Returns a MIME type for \a url.

    If the URL is a local file, this calls mimeTypeForFile.

    Otherwise the matching is done based on the file name only,
    except for schemes where file names don't mean much, like HTTP.
    This method always returns the default mimetype for HTTP URLs,
    use QNetworkAccessManager to handle HTTP URLs properly.

    A valid MIME type is always returned. If \a url doesn't match any
    known MIME type data, the default MIME type (application/octet-stream)
    is returned.
*/
MimeType MimeDatabase::mimeTypeForUrl(const QUrl &url) const
{
    if (url.isLocalFile())
        return mimeTypeForFile(url.toLocalFile());

    const QString scheme = url.scheme();
    if (scheme.startsWith(QLatin1String("http")))
        return mimeTypeForName(d->defaultMimeType());

    return mimeTypeForFile(url.path());
}

/*!
    Returns a MIME type for the given \a fileName and \a device data.

    This overload can be useful when the file is remote, and we started to
    download some of its data in a device. This allows to do full MIME type
    matching for remote files as well.

    If the device is not open, it will be opened by this function, and closed
    after the MIME type detection is completed.

    A valid MIME type is always returned. If \a device data doesn't match any
    known MIME type data, the default MIME type (application/octet-stream)
    is returned.

    This method looks at both the file name and the file contents,
    if necessary. The file extension has priority over the contents,
    but the contents will be used if the file extension is unknown, or
    matches multiple MIME types.
*/
MimeType MimeDatabase::mimeTypeForFileNameAndData(const QString &fileName, QIODevice *device) const
{
    int accuracy = 0;
    const MimeType result = d->mimeTypeForFileNameAndData(fileName, device, &accuracy);
    return result;
}

/*!
    Returns a MIME type for the given \a fileName and device \a data.

    This overload can be useful when the file is remote, and we started to
    download some of its data. This allows to do full MIME type matching for
    remote files as well.

    A valid MIME type is always returned. If \a data doesn't match any
    known MIME type data, the default MIME type (application/octet-stream)
    is returned.

    This method looks at both the file name and the file contents,
    if necessary. The file extension has priority over the contents,
    but the contents will be used if the file extension is unknown, or
    matches multiple MIME types.
*/
MimeType MimeDatabase::mimeTypeForFileNameAndData(const QString &fileName, const QByteArray &data) const
{
    QBuffer buffer(const_cast<QByteArray *>(&data));
    buffer.open(QIODevice::ReadOnly);
    int accuracy = 0;
    return d->mimeTypeForFileNameAndData(fileName, &buffer, &accuracy);
}

/*!
    Returns the list of all available MIME types.

    This can be useful for showing all MIME types to the user, for instance
    in a MIME type editor. Do not use unless really necessary in other cases
    though, prefer using the  \l {mimeTypeForData()}{mimeTypeForXxx()} methods for performance reasons.
*/
QList<MimeType> MimeDatabase::allMimeTypes() const
{
    QMutexLocker locker(&d->mutex);

    return d->allMimeTypes();
}

/*!
    \enum MimeDatabase::MatchMode

    This enum specifies how matching a file to a MIME type is performed.

    \value MatchDefault Both the file name and content are used to look for a match

    \value MatchExtension Only the file name is used to look for a match

    \value MatchContent The file content is used to look for a match
*/

QMap<int, QList<MimeMagicRule> > MimeDatabase::magicRulesForMimeType(const MimeType &mimeType)
{
    auto d = MimeDatabasePrivate::instance();
    QMutexLocker locker(&d->mutex);
    return d->provider()->magicRulesForMimeType(mimeType);
}

void MimeDatabase::setGlobPatternsForMimeType(const MimeType &mimeType, const QStringList &patterns)
{
    auto d = MimeDatabasePrivate::instance();
    QMutexLocker locker(&d->mutex);
    return d->provider()->setGlobPatternsForMimeType(mimeType, patterns);
}

void MimeDatabase::setMagicRulesForMimeType(const MimeType &mimeType, const QMap<int, QList<MimeMagicRule> > &rules)
{
    auto d = MimeDatabasePrivate::instance();
    QMutexLocker locker(&d->mutex);
    return d->provider()->setMagicRulesForMimeType(mimeType, rules);
}
