qmimedatabase.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// Copyright (C) 2015 Klaralvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author David Faure <david.faure@kdab.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include <qplatformdefs.h> // always first
 
#include "qmimedatabase.h"
#include "qmimedatabase_p.h"
 
#include "qmimeprovider_p.h"
#include "qmimetype_p.h"
 
#include <private/qfilesystementry_p.h>
 
#include <QtCore/QMap>
#include <QtCore/QFile>
#include <QtCore/QFileInfo>
#include <QtCore/QStandardPaths>
#include <QtCore/QBuffer>
#include <QtCore/QUrl>
#include <QtCore/QDebug>
 
#include <algorithm>
#include <functional>
#include <stack>
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
 
static QString directoryMimeType()
{
    return QStringLiteral("inode/directory");
}
static QString plainTextMimeType()
{
    return QStringLiteral("text/plain");
}
 
Q_GLOBAL_STATIC(QMimeDatabasePrivate, staticQMimeDatabase)
 
QMimeDatabasePrivate *QMimeDatabasePrivate::instance()
{
    return staticQMimeDatabase();
}
 
QMimeDatabasePrivate::QMimeDatabasePrivate()
    : m_defaultMimeType(QStringLiteral("application/octet-stream"))
{
}
 
QMimeDatabasePrivate::~QMimeDatabasePrivate()
{
}
 
Q_CONSTINIT
#ifdef QT_BUILD_INTERNAL
Q_CORE_EXPORT
#else
static const
#endif
int qmime_secondsBetweenChecks = 5;
 
bool QMimeDatabasePrivate::shouldCheck()
{
    if (m_lastCheck.isValid() && m_lastCheck.elapsed() < qmime_secondsBetweenChecks * 1000)
        return false;
    m_lastCheck.start();
    return true;
}
 
static QStringList locateMimeDirectories()
{
    return QStandardPaths::locateAll(QStandardPaths::GenericDataLocation, QStringLiteral("mime"), QStandardPaths::LocateDirectory);
}
 
#if defined(Q_OS_UNIX) && !defined(Q_OS_NACL) && !defined(Q_OS_INTEGRITY)
#  define QT_USE_MMAP
#endif
 
void QMimeDatabasePrivate::loadProviders()
{
    // We use QStandardPaths every time to check if new files appeared
    const QStringList mimeDirs = locateMimeDirectories();
    const auto fdoIterator = std::find_if(mimeDirs.constBegin(), mimeDirs.constEnd(), [](const QString &mimeDir) -> bool {
        return QFileInfo::exists(mimeDir + "/packages/freedesktop.org.xml"_L1); }
    );
    const bool needInternalDB = QMimeXMLProvider::InternalDatabaseAvailable && fdoIterator == mimeDirs.constEnd();
    //qDebug() << "mime dirs:" << mimeDirs;
 
    Providers currentProviders;
    std::swap(m_providers, currentProviders);
 
    m_providers.reserve(mimeDirs.size() + (needInternalDB ? 1 : 0));
 
    for (const QString &mimeDir : mimeDirs) {
        const QString cacheFile = mimeDir + "/mime.cache"_L1;
        // Check if we already have a provider for this dir
        const auto predicate = [mimeDir](const std::unique_ptr<QMimeProviderBase> &prov)
        {
            return prov && prov->directory() == mimeDir;
        };
        const auto it = std::find_if(currentProviders.begin(), currentProviders.end(), predicate);
        if (it == currentProviders.end()) {
            std::unique_ptr<QMimeProviderBase> provider;
#if defined(QT_USE_MMAP)
            if (qEnvironmentVariableIsEmpty("QT_NO_MIME_CACHE") && QFileInfo::exists(cacheFile)) {
                provider.reset(new QMimeBinaryProvider(this, mimeDir));
                //qDebug() << "Created binary provider for" << mimeDir;
                if (!provider->isValid()) {
                    provider.reset();
                }
            }
#endif
            if (!provider) {
                provider.reset(new QMimeXMLProvider(this, mimeDir));
                //qDebug() << "Created XML provider for" << mimeDir;
            }
            m_providers.push_back(std::move(provider));
        } else {
            auto provider = std::move(*it); // take provider out of the vector
            provider->ensureLoaded();
            if (!provider->isValid()) {
                provider.reset(new QMimeXMLProvider(this, mimeDir));
                //qDebug() << "Created XML provider to replace binary provider for" << mimeDir;
            }
            m_providers.push_back(std::move(provider));
        }
    }
    // mimeDirs is sorted "most local first, most global last"
    // so the internal XML DB goes at the end
    if (needInternalDB) {
        // Check if we already have a provider for the InternalDatabase
        const auto isInternal = [](const std::unique_ptr<QMimeProviderBase> &prov)
        {
            return prov && prov->isInternalDatabase();
        };
        const auto it = std::find_if(currentProviders.begin(), currentProviders.end(), isInternal);
        if (it == currentProviders.end()) {
            m_providers.push_back(Providers::value_type(new QMimeXMLProvider(this, QMimeXMLProvider::InternalDatabase)));
        } else {
            m_providers.push_back(std::move(*it));
        }
    }
 
    // Handle mimetypes with glob-deleteall tags (from XML providers)
    auto it = m_providers.begin();
    const auto end = m_providers.end();
    for (;it != end; ++it) {
        const QStringList &list = (*it)->m_mimeTypesWithDeletedGlobs;
        if (list.isEmpty())
            continue;
        // Each Provider affects Providers with lower precedence
        auto nextIt = it + 1;
        for (; nextIt != end; ++nextIt)
            (*nextIt)->excludeMimeTypeGlobs(list);
    }
}
 
const QMimeDatabasePrivate::Providers &QMimeDatabasePrivate::providers()
{
#ifndef Q_OS_WASM // stub implementation always returns true
    Q_ASSERT(!mutex.tryLock()); // caller should have locked mutex
#endif
    if (m_providers.empty()) {
        loadProviders();
        m_lastCheck.start();
    } else {
        if (shouldCheck())
            loadProviders();
    }
    return m_providers;
}
 
QString QMimeDatabasePrivate::resolveAlias(const QString &nameOrAlias)
{
    for (const auto &provider : providers()) {
        const QString ret = provider->resolveAlias(nameOrAlias);
        if (!ret.isEmpty())
            return ret;
    }
    return nameOrAlias;
}
 
QMimeType QMimeDatabasePrivate::mimeTypeForName(const QString &nameOrAlias)
{
    const QString mimeName = resolveAlias(nameOrAlias);
    for (const auto &provider : providers()) {
        QMimeType mime = provider->mimeTypeForName(mimeName);
        if (mime.isValid())
            return mime;
    }
    return {};
}
 
QStringList QMimeDatabasePrivate::mimeTypeForFileName(const QString &fileName)
{
    if (fileName.endsWith(u'/'))
        return { directoryMimeType() };
 
    const QMimeGlobMatchResult result = findByFileName(fileName);
    QStringList matchingMimeTypes = result.m_matchingMimeTypes;
    matchingMimeTypes.sort(); // make it deterministic
    return matchingMimeTypes;
}
 
QMimeGlobMatchResult QMimeDatabasePrivate::findByFileName(const QString &fileName)
{
    QMimeGlobMatchResult result;
    const QString fileNameExcludingPath = QFileSystemEntry(fileName).fileName();
    for (const auto &provider : providers())
        provider->addFileNameMatches(fileNameExcludingPath, result);
    return result;
}
 
void QMimeDatabasePrivate::loadMimeTypePrivate(QMimeTypePrivate &mimePrivate)
{
    QMutexLocker locker(&mutex);
    if (mimePrivate.name.isEmpty())
        return; // invalid mimetype
    if (!mimePrivate.loaded) { // XML provider sets loaded=true, binary provider does this on demand
        Q_ASSERT(mimePrivate.fromCache);
        bool found = false;
        for (const auto &provider : providers()) {
            if (provider->loadMimeTypePrivate(mimePrivate)) {
                found = true;
                break;
            }
        }
        if (!found) {
            const QString file = mimePrivate.name + ".xml"_L1;
            qWarning() << "No file found for" << file << ", even though update-mime-info said it would exist.\n"
                          "Either it was just removed, or the directory doesn't have executable permission..."
                       << locateMimeDirectories();
        }
        mimePrivate.loaded = true;
    }
}
 
void QMimeDatabasePrivate::loadGenericIcon(QMimeTypePrivate &mimePrivate)
{
    QMutexLocker locker(&mutex);
    if (mimePrivate.fromCache) {
        mimePrivate.genericIconName.clear();
        for (const auto &provider : providers()) {
            provider->loadGenericIcon(mimePrivate);
            if (!mimePrivate.genericIconName.isEmpty())
                break;
        }
    }
}
 
void QMimeDatabasePrivate::loadIcon(QMimeTypePrivate &mimePrivate)
{
    QMutexLocker locker(&mutex);
    if (mimePrivate.fromCache) {
        mimePrivate.iconName.clear();
        for (const auto &provider : providers()) {
            provider->loadIcon(mimePrivate);
            if (!mimePrivate.iconName.isEmpty())
                break;
        }
    }
}
 
QString QMimeDatabasePrivate::fallbackParent(const QString &mimeTypeName) const
{
    const QStringView myGroup = QStringView{mimeTypeName}.left(mimeTypeName.indexOf(u'/'));
    // All text/* types are subclasses of text/plain.
    if (myGroup == "text"_L1 && mimeTypeName != plainTextMimeType())
        return plainTextMimeType();
    // All real-file mimetypes implicitly derive from application/octet-stream
    if (myGroup != "inode"_L1 &&
        // ignore non-file extensions
        myGroup != "all"_L1 && myGroup != "fonts"_L1 && myGroup != "print"_L1 && myGroup != "uri"_L1
        && mimeTypeName != defaultMimeType()) {
        return defaultMimeType();
    }
    return QString();
}
 
QStringList QMimeDatabasePrivate::mimeParents(const QString &mimeName)
{
    QMutexLocker locker(&mutex);
    return parents(mimeName);
}
 
QStringList QMimeDatabasePrivate::parents(const QString &mimeName)
{
    Q_ASSERT(!mutex.tryLock());
    QStringList result;
    for (const auto &provider : providers())
        provider->addParents(mimeName, result);
    if (result.isEmpty()) {
        const QString parent = fallbackParent(mimeName);
        if (!parent.isEmpty())
            result.append(parent);
    }
    return result;
}
 
QStringList QMimeDatabasePrivate::listAliases(const QString &mimeName)
{
    QMutexLocker locker(&mutex);
    QStringList result;
    for (const auto &provider : providers())
        provider->addAliases(mimeName, result);
    return result;
}
 
bool QMimeDatabasePrivate::mimeInherits(const QString &mime, const QString &parent)
{
    QMutexLocker locker(&mutex);
    return inherits(mime, parent);
}
 
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 128 bytes (see shared-mime spec)
    const char *p = data.constData();
    const char *e = p + qMin(128, data.size());
    for ( ; p < e; ++p) {
        if (static_cast<unsigned char>(*p) < 32 && *p != 9 && *p !=10 && *p != 13)
            return false;
    }
 
    return true;
}
 
QMimeType QMimeDatabasePrivate::findByData(const QByteArray &data, int *accuracyPtr)
{
    if (data.isEmpty()) {
        *accuracyPtr = 100;
        return mimeTypeForName(QStringLiteral("application/x-zerosize"));
    }
 
    *accuracyPtr = 0;
    QMimeType candidate;
    for (const auto &provider : providers())
        provider->findByMagic(data, accuracyPtr, candidate);
 
    if (candidate.isValid())
        return candidate;
 
    if (isTextFile(data)) {
        *accuracyPtr = 5;
        return mimeTypeForName(plainTextMimeType());
    }
 
    return mimeTypeForName(defaultMimeType());
}
 
QMimeType QMimeDatabasePrivate::mimeTypeForFileNameAndData(const QString &fileName, QIODevice *device)
{
    // 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.
 
    // Pass 1) Try to match on the file name
    QMimeGlobMatchResult candidatesByName = findByFileName(fileName);
    if (candidatesByName.m_allMatchingMimeTypes.size() == 1) {
        const QMimeType mime = mimeTypeForName(candidatesByName.m_matchingMimeTypes.at(0));
        if (mime.isValid())
            return mime;
        candidatesByName = {};
    }
 
    // Extension is unknown, or matches multiple mimetypes.
    // Pass 2) Match on content, if we can read the data
    const auto matchOnContent = [this, &candidatesByName](QIODevice *device) {
        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;
            QMimeType 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 highest-weight glob match, use it
                if (candidatesByName.m_matchingMimeTypes.contains(sniffedMime)) {
                    return candidateByData;
                }
                for (const QString &m : std::as_const(candidatesByName.m_allMatchingMimeTypes)) {
                    if (inherits(m, sniffedMime)) {
                        // We have magic + pattern pointing to this, so it's a pretty good match
                        return mimeTypeForName(m);
                    }
                }
                if (candidatesByName.m_allMatchingMimeTypes.isEmpty()) {
                    // No glob, use magic
                    return candidateByData;
                }
            }
        }
 
        if (candidatesByName.m_allMatchingMimeTypes.size() > 1) {
            candidatesByName.m_matchingMimeTypes.sort(); // make it deterministic
            const QMimeType mime = mimeTypeForName(candidatesByName.m_matchingMimeTypes.at(0));
            if (mime.isValid())
                return mime;
        }
 
        return mimeTypeForName(defaultMimeType());
    };
 
    if (device)
        return matchOnContent(device);
 
    QFile fallbackFile(fileName);
    return matchOnContent(&fallbackFile);
}
 
QMimeType QMimeDatabasePrivate::mimeTypeForFileExtension(const QString &fileName)
{
    const QStringList matches = mimeTypeForFileName(fileName);
    if (matches.isEmpty()) {
        return mimeTypeForName(defaultMimeType());
    } else {
        // We have to pick one in case of multiple matches.
        return mimeTypeForName(matches.first());
    }
}
 
QMimeType QMimeDatabasePrivate::mimeTypeForData(QIODevice *device)
{
    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);
        QMimeType result = findByData(data, &accuracy);
        if (openedByUs)
            device->close();
        return result;
    }
    return mimeTypeForName(defaultMimeType());
}
 
QMimeType QMimeDatabasePrivate::mimeTypeForFile(const QString &fileName,
                                                const QFileInfo &fileInfo,
                                                QMimeDatabase::MatchMode mode)
{
    if (false) {
#ifdef Q_OS_UNIX
    } else if (fileInfo.isNativePath()) {
        // If this is a local file, we'll want to do a stat() ourselves so we can
        // detect additional inode types. In addition we want to follow symlinks.
        const QByteArray nativeFilePath = QFile::encodeName(fileName);
        QT_STATBUF statBuffer;
        if (QT_STAT(nativeFilePath.constData(), &statBuffer) == 0) {
            if (S_ISDIR(statBuffer.st_mode))
                return mimeTypeForName(directoryMimeType());
            if (S_ISCHR(statBuffer.st_mode))
                return mimeTypeForName(QStringLiteral("inode/chardevice"));
            if (S_ISBLK(statBuffer.st_mode))
                return mimeTypeForName(QStringLiteral("inode/blockdevice"));
            if (S_ISFIFO(statBuffer.st_mode))
                return mimeTypeForName(QStringLiteral("inode/fifo"));
            if (S_ISSOCK(statBuffer.st_mode))
                return mimeTypeForName(QStringLiteral("inode/socket"));
        }
#endif
    } else if (fileInfo.isDir()) {
        return mimeTypeForName(directoryMimeType());
    }
 
    switch (mode) {
    case QMimeDatabase::MatchDefault:
        break;
    case QMimeDatabase::MatchExtension:
        return mimeTypeForFileExtension(fileName);
    case QMimeDatabase::MatchContent: {
        QFile file(fileName);
        return mimeTypeForData(&file);
    }
    }
    // MatchDefault:
    return mimeTypeForFileNameAndData(fileName, nullptr);
}
 
QList<QMimeType> QMimeDatabasePrivate::allMimeTypes()
{
    QList<QMimeType> result;
    for (const auto &provider : providers())
        provider->addAllMimeTypes(result);
    return result;
}
 
bool QMimeDatabasePrivate::inherits(const QString &mime, const QString &parent)
{
    const QString resolvedParent = resolveAlias(parent);
    std::stack<QString, QStringList> toCheck;
    toCheck.push(mime);
    while (!toCheck.empty()) {
        if (toCheck.top() == resolvedParent)
            return true;
        const QString mimeName = toCheck.top();
        toCheck.pop();
        const auto parentList = parents(mimeName);
        for (const QString &par : parentList)
            toCheck.push(resolveAlias(par));
    }
    return false;
}
 
QMimeDatabase::QMimeDatabase() :
        d(staticQMimeDatabase())
{
}
 
QMimeDatabase::~QMimeDatabase()
{
    d = nullptr;
}
 
QMimeType QMimeDatabase::mimeTypeForName(const QString &nameOrAlias) const
{
    QMutexLocker locker(&d->mutex);
 
    return d->mimeTypeForName(nameOrAlias);
}
 
QMimeType QMimeDatabase::mimeTypeForFile(const QFileInfo &fileInfo, MatchMode mode) const
{
    QMutexLocker locker(&d->mutex);
 
    return d->mimeTypeForFile(fileInfo.filePath(), fileInfo, mode);
}
 
QMimeType QMimeDatabase::mimeTypeForFile(const QString &fileName, MatchMode mode) const
{
    QMutexLocker locker(&d->mutex);
 
    if (mode == MatchExtension) {
        return d->mimeTypeForFileExtension(fileName);
    } else {
        QFileInfo fileInfo(fileName);
        return d->mimeTypeForFile(fileName, fileInfo, mode);
    }
}
 
QList<QMimeType> QMimeDatabase::mimeTypesForFileName(const QString &fileName) const
{
    QMutexLocker locker(&d->mutex);
 
    const QStringList matches = d->mimeTypeForFileName(fileName);
    QList<QMimeType> mimes;
    mimes.reserve(matches.size());
    for (const QString &mime : matches)
        mimes.append(d->mimeTypeForName(mime));
    return mimes;
}
QString QMimeDatabase::suffixForFileName(const QString &fileName) const
{
    QMutexLocker locker(&d->mutex);
    const qsizetype suffixLength = d->findByFileName(fileName).m_knownSuffixLength;
    return fileName.right(suffixLength);
}
 
QMimeType QMimeDatabase::mimeTypeForData(const QByteArray &data) const
{
    QMutexLocker locker(&d->mutex);
 
    int accuracy = 0;
    return d->findByData(data, &accuracy);
}
 
QMimeType QMimeDatabase::mimeTypeForData(QIODevice *device) const
{
    QMutexLocker locker(&d->mutex);
 
    return d->mimeTypeForData(device);
}
 
QMimeType QMimeDatabase::mimeTypeForUrl(const QUrl &url) const
{
    if (url.isLocalFile())
        return mimeTypeForFile(url.toLocalFile());
 
    const QString scheme = url.scheme();
    if (scheme.startsWith("http"_L1) || scheme == "mailto"_L1)
        return mimeTypeForName(d->defaultMimeType());
 
    return mimeTypeForFile(url.path(), MatchExtension);
}
 
QMimeType QMimeDatabase::mimeTypeForFileNameAndData(const QString &fileName, QIODevice *device) const
{
    QMutexLocker locker(&d->mutex);
 
    if (fileName.endsWith(u'/'))
        return d->mimeTypeForName(directoryMimeType());
 
    const QMimeType result = d->mimeTypeForFileNameAndData(fileName, device);
    return result;
}
 
QMimeType QMimeDatabase::mimeTypeForFileNameAndData(const QString &fileName, const QByteArray &data) const
{
    QMutexLocker locker(&d->mutex);
 
    if (fileName.endsWith(u'/'))
        return d->mimeTypeForName(directoryMimeType());
 
    QBuffer buffer(const_cast<QByteArray *>(&data));
    buffer.open(QIODevice::ReadOnly);
    return d->mimeTypeForFileNameAndData(fileName, &buffer);
}
 
QList<QMimeType> QMimeDatabase::allMimeTypes() const
{
    QMutexLocker locker(&d->mutex);
 
    return d->allMimeTypes();
}
 
QT_END_NAMESPACE