Icon associated with a file type in Linux

Finally I found a solution to my problem, independent of the operating system, using the QFileIconProvider class that provides Qt as of version 5.2. The following link was also useful.

My final code is as follows:

#include <QIcon>
#include <QString>

#if ((QT_VERSION_MAJOR > 5) || (QT_VERSION_MAJOR == 5 && QT_VERSION_MINOR >= 2))

#include <QFileIconProvider>

QIcon IconFromFile(const QString& fileName)
{
    return QFileIconProvider().icon(QFileInfo(fileName));
}

#else

#include <QPixmap>
#if defined(Q_OS_WIN)
#include <windows.h>

#include <QFileInfo>
#include <QtWinExtras/QtWin>

QIcon IconFromFile(const QString& fileName)
{
    QIcon qIcon;
    HICON hIcon;

    hIcon = ExtractIconW(NULL, (const WCHAR*)fileName.constData(), 0);
    if(hIcon == NULL)
    {
        SHFILEINFO shfi;
        DWORD dwFileAttributes;

        memset(&shfi, 0, sizeof(shfi));
        if(QFileInfo(fileName).isDir())
            dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
        else
            dwFileAttributes = FILE_ATTRIBUTE_ARCHIVE;

        SHGetFileInfoW((const WCHAR*)fileName.constData(),
                       dwFileAttributes,
                       &shfi,
                       sizeof(SHFILEINFO),
                       SHGFI_USEFILEATTRIBUTES | SHGFI_ICON | SHGFI_SMALLICON);

        hIcon = shfi.hIcon;
    }
    if(hIcon != NULL)
    {
#if (QT_VERSION_MAJOR == 4)
        qIcon = QIcon(QPixmap::fromWinHICON(hIcon));
#else
        qIcon = QtWin::fromHICON(hIcon);
#endif
        DestroyIcon(hIcon);
    }
    return qIcon;
}
#elif defined(Q_OS_LINUX)
#include <QMimeData>
#include <QMimeDatabase>
#include <QApplication>
#include <QStyle>
#include <QFileInfo>

QIcon IconFromFile(const QString& fileName)
{
    QMimeDatabase db;
    QIcon icon;
    QList<QMimeType> types = db.mimeTypesForFileName(fileName);
    for(int i = 0; i < types.count(); i++)
    {
        icon = QIcon::fromTheme(types[i].iconName());
        if(!icon.isNull())
            return icon;
    }
    if(QFileInfo(fileName).isDir())
        return QApplication::style()->standardIcon(QStyle::SP_DirIcon);
    return QApplication::style()->standardIcon(QStyle::SP_FileIcon);
}

#endif

#endif

Greetings! I hope others will find my solution.