/****************************************************************************
**
** Copyright (C) 2014 Ivan Komissarov <ABBAPOH@gmail.com>
** Copyright (C) 2016 Intel Corporation.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
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** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
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** $QT_END_LICENSE$
**
****************************************************************************/

#include "qstorageinfo_p.h"

#include <QtCore/qdiriterator.h>
#include <QtCore/qfileinfo.h>
#include <QtCore/qtextstream.h>

#include <QtCore/private/qcore_unix_p.h>

#include <errno.h>
#include <sys/stat.h>

#if defined(Q_OS_BSD4)
#  include <sys/mount.h>
#  include <sys/statvfs.h>
#elif defined(Q_OS_ANDROID)
#  include <sys/mount.h>
#  include <sys/vfs.h>
#  include <mntent.h>
#elif defined(Q_OS_LINUX) || defined(Q_OS_HURD)
#  include <mntent.h>
#  include <sys/statvfs.h>
#elif defined(Q_OS_SOLARIS)
#  include <sys/mnttab.h>
#  include <sys/statvfs.h>
#elif defined(Q_OS_HAIKU)
#  include <Directory.h>
#  include <Path.h>
#  include <Volume.h>
#  include <VolumeRoster.h>
#  include <fs_info.h>
#  include <sys/statvfs.h>
#else
#  include <sys/statvfs.h>
#endif

#if defined(Q_OS_BSD4)
#  if defined(Q_OS_NETBSD)
#    define QT_STATFSBUF struct statvfs
#    define QT_STATFS    ::statvfs
#  else
#    define QT_STATFSBUF struct statfs
#    define QT_STATFS    ::statfs
#  endif

#  if !defined(ST_RDONLY)
#    define ST_RDONLY MNT_RDONLY
#  endif
#  if !defined(_STATFS_F_FLAGS) && !defined(Q_OS_NETBSD)
#    define _STATFS_F_FLAGS 1
#  endif
#elif defined(Q_OS_ANDROID)
#  define QT_STATFS    ::statfs
#  define QT_STATFSBUF struct statfs
#  if !defined(ST_RDONLY)
#    define ST_RDONLY 1 // hack for missing define on Android
#  endif
#elif defined(Q_OS_HAIKU)
#  define QT_STATFSBUF struct statvfs
#  define QT_STATFS    ::statvfs
#else
#  if defined(QT_LARGEFILE_SUPPORT)
#    define QT_STATFSBUF struct statvfs64
#    define QT_STATFS    ::statvfs64
#  else
#    define QT_STATFSBUF struct statvfs
#    define QT_STATFS    ::statvfs
#  endif // QT_LARGEFILE_SUPPORT
#endif // Q_OS_BSD4

QT_BEGIN_NAMESPACE

class QStorageIterator
{
public:
    QStorageIterator();
    ~QStorageIterator();

    inline bool isValid() const;
    inline bool next();
    inline QString rootPath() const;
    inline QByteArray fileSystemType() const;
    inline QByteArray device() const;
    inline QByteArray options() const;
private:
#if defined(Q_OS_BSD4)
    QT_STATFSBUF *stat_buf;
    int entryCount;
    int currentIndex;
#elif defined(Q_OS_SOLARIS)
    FILE *fp;
    mnttab mnt;
#elif defined(Q_OS_ANDROID)
    QFile file;
    QByteArray m_rootPath;
    QByteArray m_fileSystemType;
    QByteArray m_device;
    QByteArray m_options;
#elif defined(Q_OS_LINUX) || defined(Q_OS_HURD)
    FILE *fp;
    mntent mnt;
    QByteArray buffer;
#elif defined(Q_OS_HAIKU)
    BVolumeRoster m_volumeRoster;

    QByteArray m_rootPath;
    QByteArray m_fileSystemType;
    QByteArray m_device;
#endif
};

template <typename String>
static bool isParentOf(const String &parent, const QString &dirName)
{
    return dirName.startsWith(parent) &&
            (dirName.size() == parent.size() || dirName.at(parent.size()) == QLatin1Char('/') ||
             parent.size() == 1);
}

static bool shouldIncludeFs(const QStorageIterator &it)
{
    /*
     * This function implements a heuristic algorithm to determine whether a
     * given mount should be reported to the user. Our objective is to list
     * only entries that the end-user would find useful.
     *
     * We therefore ignore:
     *  - mounted in /dev, /proc, /sys: special mounts
     *    (this will catch /sys/fs/cgroup, /proc/sys/fs/binfmt_misc, /dev/pts,
     *    some of which are tmpfs on Linux)
     *  - mounted in /var/run or /var/lock: most likely pseudofs
     *    (on earlier systemd versions, /var/run was a bind-mount of /run, so
     *    everything would be unnecessarily duplicated)
     *  - filesystem type is "rootfs": artifact of the root-pivot on some Linux
     *    initrd
     *  - if the filesystem total size is zero, it's a pseudo-fs (not checked here).
     */

    QString mountDir = it.rootPath();
    if (isParentOf(QLatin1String("/dev"), mountDir)
        || isParentOf(QLatin1String("/proc"), mountDir)
        || isParentOf(QLatin1String("/sys"), mountDir)
        || isParentOf(QLatin1String("/var/run"), mountDir)
        || isParentOf(QLatin1String("/var/lock"), mountDir)) {
        return false;
    }

#ifdef Q_OS_LINUX
    if (it.fileSystemType() == "rootfs")
        return false;
#endif

    // size checking in mountedVolumes()
    return true;
}

#if defined(Q_OS_BSD4)

#ifndef MNT_NOWAIT
#  define MNT_NOWAIT 0
#endif

inline QStorageIterator::QStorageIterator()
    : entryCount(::getmntinfo(&stat_buf, MNT_NOWAIT)),
      currentIndex(-1)
{
}

inline QStorageIterator::~QStorageIterator()
{
}

inline bool QStorageIterator::isValid() const
{
    return entryCount != -1;
}

inline bool QStorageIterator::next()
{
    return ++currentIndex < entryCount;
}

inline QString QStorageIterator::rootPath() const
{
    return QFile::decodeName(stat_buf[currentIndex].f_mntonname);
}

inline QByteArray QStorageIterator::fileSystemType() const
{
    return QByteArray(stat_buf[currentIndex].f_fstypename);
}

inline QByteArray QStorageIterator::device() const
{
    return QByteArray(stat_buf[currentIndex].f_mntfromname);
}

inline QByteArray QStorageIterator::options() const
{
    return QByteArray();
}

#elif defined(Q_OS_SOLARIS)

static const char pathMounted[] = "/etc/mnttab";

inline QStorageIterator::QStorageIterator()
{
    const int fd = qt_safe_open(pathMounted, O_RDONLY);
    fp = ::fdopen(fd, "r");
}

inline QStorageIterator::~QStorageIterator()
{
    if (fp)
        ::fclose(fp);
}

inline bool QStorageIterator::isValid() const
{
    return fp != Q_NULLPTR;
}

inline bool QStorageIterator::next()
{
    return ::getmntent(fp, &mnt) == 0;
}

inline QString QStorageIterator::rootPath() const
{
    return QFile::decodeName(mnt.mnt_mountp);
}

inline QByteArray QStorageIterator::fileSystemType() const
{
    return QByteArray(mnt.mnt_fstype);
}

inline QByteArray QStorageIterator::device() const
{
    return QByteArray(mnt.mnt_mntopts);
}

#elif defined(Q_OS_ANDROID)

static const QLatin1String pathMounted("/proc/mounts");

inline QStorageIterator::QStorageIterator()
{
    file.setFileName(pathMounted);
    file.open(QIODevice::ReadOnly | QIODevice::Text);
}

inline QStorageIterator::~QStorageIterator()
{
}

inline bool QStorageIterator::isValid() const
{
    return file.isOpen();
}

inline bool QStorageIterator::next()
{
    QList<QByteArray> data;
    do {
        const QByteArray line = file.readLine();
        data = line.split(' ');
    } while (data.count() < 3 && !file.atEnd());

    if (file.atEnd())
        return false;
    m_device = data.at(0);
    m_rootPath = data.at(1);
    m_fileSystemType = data.at(2);
    m_options = data.at(3);

    return true;
}

inline QString QStorageIterator::rootPath() const
{
    return QFile::decodeName(m_rootPath);
}

inline QByteArray QStorageIterator::fileSystemType() const
{
    return m_fileSystemType;
}

inline QByteArray QStorageIterator::device() const
{
    return m_device;
}

inline QByteArray QStorageIterator::options() const
{
    return m_options;
}

#elif defined(Q_OS_LINUX) || defined(Q_OS_HURD)

static const char pathMounted[] = "/etc/mtab";
static const int bufferSize = 1024; // 2 paths (mount point+device) and metainfo;
                                    // should be enough

inline QStorageIterator::QStorageIterator() :
    buffer(QByteArray(bufferSize, 0))
{
    fp = ::setmntent(pathMounted, "r");
}

inline QStorageIterator::~QStorageIterator()
{
    if (fp)
        ::endmntent(fp);
}

inline bool QStorageIterator::isValid() const
{
    return fp != Q_NULLPTR;
}

inline bool QStorageIterator::next()
{
    return ::getmntent_r(fp, &mnt, buffer.data(), buffer.size()) != Q_NULLPTR;
}

inline QString QStorageIterator::rootPath() const
{
    return QFile::decodeName(mnt.mnt_dir);
}

inline QByteArray QStorageIterator::fileSystemType() const
{
    return QByteArray(mnt.mnt_type);
}

inline QByteArray QStorageIterator::device() const
{
    return QByteArray(mnt.mnt_fsname);
}

inline QByteArray QStorageIterator::options() const
{
    return QByteArray(mnt.mnt_opts);
}

#elif defined(Q_OS_HAIKU)
inline QStorageIterator::QStorageIterator()
{
}

inline QStorageIterator::~QStorageIterator()
{
}

inline bool QStorageIterator::isValid() const
{
    return true;
}

inline bool QStorageIterator::next()
{
    BVolume volume;

    if (m_volumeRoster.GetNextVolume(&volume) != B_OK)
        return false;

    BDirectory directory;
    if (volume.GetRootDirectory(&directory) != B_OK)
        return false;

    const BPath path(&directory);

    fs_info fsInfo;
    memset(&fsInfo, 0, sizeof(fsInfo));

    if (fs_stat_dev(volume.Device(), &fsInfo) != 0)
        return false;

    m_rootPath = path.Path();
    m_fileSystemType = QByteArray(fsInfo.fsh_name);

    const QByteArray deviceName(fsInfo.device_name);
    m_device = (deviceName.isEmpty() ? QByteArray::number(qint32(volume.Device())) : deviceName);

    return true;
}

inline QString QStorageIterator::rootPath() const
{
    return QFile::decodeName(m_rootPath);
}

inline QByteArray QStorageIterator::fileSystemType() const
{
    return m_fileSystemType;
}

inline QByteArray QStorageIterator::device() const
{
    return m_device;
}

inline QByteArray QStorageIterator::options() const
{
    return QByteArray();
}

#else

inline QStorageIterator::QStorageIterator()
{
}

inline QStorageIterator::~QStorageIterator()
{
}

inline bool QStorageIterator::isValid() const
{
    return false;
}

inline bool QStorageIterator::next()
{
    return false;
}

inline QString QStorageIterator::rootPath() const
{
    return QString();
}

inline QByteArray QStorageIterator::fileSystemType() const
{
    return QByteArray();
}

inline QByteArray QStorageIterator::device() const
{
    return QByteArray();
}

inline QByteArray QStorageIterator::options() const
{
    return QByteArray();
}

#endif

static QByteArray extractSubvolume(const QStorageIterator &it)
{
#ifdef Q_OS_LINUX
    if (it.fileSystemType() == "btrfs") {
        const QByteArrayList opts = it.options().split(',');
        QByteArray id;
        for (const QByteArray &opt : opts) {
            static const char subvol[] = "subvol=";
            static const char subvolid[] = "subvolid=";
            if (opt.startsWith(subvol))
                return std::move(opt).mid(strlen(subvol));
            if (opt.startsWith(subvolid))
                id = std::move(opt).mid(strlen(subvolid));
        }

        // if we didn't find the subvolume name, return the subvolume ID
        return id;
    }
#else
    Q_UNUSED(it);
#endif
    return QByteArray();
}

void QStorageInfoPrivate::initRootPath()
{
    rootPath = QFileInfo(rootPath).canonicalFilePath();

    if (rootPath.isEmpty())
        return;

    QStorageIterator it;
    if (!it.isValid()) {
        rootPath = QStringLiteral("/");
        return;
    }

    int maxLength = 0;
    const QString oldRootPath = rootPath;
    rootPath.clear();

    while (it.next()) {
        const QString mountDir = it.rootPath();
        const QByteArray fsName = it.fileSystemType();
        // we try to find most suitable entry
        if (isParentOf(mountDir, oldRootPath) && maxLength < mountDir.length()) {
            maxLength = mountDir.length();
            rootPath = mountDir;
            device = it.device();
            fileSystemType = fsName;
            subvolume = extractSubvolume(it);
        }
    }
}

#ifdef Q_OS_LINUX
// udev encodes the labels with ID_LABEL_FS_ENC which is done with
// blkid_encode_string(). Within this function some 1-byte utf-8
// characters not considered safe (e.g. '\' or ' ') are encoded as hex
static QString decodeFsEncString(const QString &str)
{
    QString decoded;
    decoded.reserve(str.size());

    int i = 0;
    while (i < str.size()) {
        if (i <= str.size() - 4) {    // we need at least four characters \xAB
            if (str.at(i) == QLatin1Char('\\') &&
                str.at(i+1) == QLatin1Char('x')) {
                bool bOk;
                const int code = str.midRef(i+2, 2).toInt(&bOk, 16);
                // only decode characters between 0x20 and 0x7f but not
                // the backslash to prevent collisions
                if (bOk && code >= 0x20 && code < 0x80 && code != '\\') {
                    decoded += QChar(code);
                    i += 4;
                    continue;
                }
            }
        }
        decoded += str.at(i);
        ++i;
    }
    return decoded;
}
#endif

static inline QString retrieveLabel(const QByteArray &device)
{
#ifdef Q_OS_LINUX
    static const char pathDiskByLabel[] = "/dev/disk/by-label";

    QFileInfo devinfo(QFile::decodeName(device));
    QString devicePath = devinfo.canonicalFilePath();

    QDirIterator it(QLatin1String(pathDiskByLabel), QDir::NoDotAndDotDot);
    while (it.hasNext()) {
        it.next();
        QFileInfo fileInfo(it.fileInfo());
        if (fileInfo.isSymLink() && fileInfo.symLinkTarget() == devicePath)
            return decodeFsEncString(fileInfo.fileName());
    }
#elif defined Q_OS_HAIKU
    fs_info fsInfo;
    memset(&fsInfo, 0, sizeof(fsInfo));

    int32 pos = 0;
    dev_t dev;
    while ((dev = next_dev(&pos)) >= 0) {
        if (fs_stat_dev(dev, &fsInfo) != 0)
            continue;

        if (qstrcmp(fsInfo.device_name, device.constData()) == 0)
            return QString::fromLocal8Bit(fsInfo.volume_name);
    }
#else
    Q_UNUSED(device);
#endif

    return QString();
}

void QStorageInfoPrivate::doStat()
{
    initRootPath();
    if (rootPath.isEmpty())
        return;

    retrieveVolumeInfo();
    name = retrieveLabel(device);
}

void QStorageInfoPrivate::retrieveVolumeInfo()
{
    QT_STATFSBUF statfs_buf;
    int result;
    EINTR_LOOP(result, QT_STATFS(QFile::encodeName(rootPath).constData(), &statfs_buf));
    if (result == 0) {
        valid = true;
        ready = true;

#if defined(Q_OS_INTEGRITY) || (defined(Q_OS_BSD4) && !defined(Q_OS_NETBSD))
        bytesTotal = statfs_buf.f_blocks * statfs_buf.f_bsize;
        bytesFree = statfs_buf.f_bfree * statfs_buf.f_bsize;
        bytesAvailable = statfs_buf.f_bavail * statfs_buf.f_bsize;
#else
        bytesTotal = statfs_buf.f_blocks * statfs_buf.f_frsize;
        bytesFree = statfs_buf.f_bfree * statfs_buf.f_frsize;
        bytesAvailable = statfs_buf.f_bavail * statfs_buf.f_frsize;
#endif
        blockSize = statfs_buf.f_bsize;
#if defined(Q_OS_ANDROID) || defined(Q_OS_BSD4) || defined(Q_OS_INTEGRITY)
#if defined(_STATFS_F_FLAGS)
        readOnly = (statfs_buf.f_flags & ST_RDONLY) != 0;
#endif
#else
        readOnly = (statfs_buf.f_flag & ST_RDONLY) != 0;
#endif
    }
}

QList<QStorageInfo> QStorageInfoPrivate::mountedVolumes()
{
    QStorageIterator it;
    if (!it.isValid())
        return QList<QStorageInfo>() << root();

    QList<QStorageInfo> volumes;

    while (it.next()) {
        if (!shouldIncludeFs(it))
            continue;

        const QString mountDir = it.rootPath();
        QStorageInfo info(mountDir);
        if (info.bytesTotal() == 0)
            continue;
        volumes.append(info);
    }

    return volumes;
}

QStorageInfo QStorageInfoPrivate::root()
{
    return QStorageInfo(QStringLiteral("/"));
}

QT_END_NAMESPACE