1 files changed, 348 insertions, 0 deletions
diff --git a/src/corelib/io/qstorageinfo_linux.cpp b/src/corelib/io/qstorageinfo_linux.cpp
new file mode 100644
index 0000000000..b4360f9164
--- /dev/null
+++ b/src/corelib/io/qstorageinfo_linux.cpp
@@ -0,0 +1,348 @@
+// Copyright (C) 2021 The Qt Company Ltd.
+// Copyright (C) 2014 Ivan Komissarov <ABBAPOH@gmail.com>
+// Copyright (C) 2016 Intel Corporation.
+// Copyright (C) 2023 Ahmad Samir <a.samirh78@gmail.com>
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qstorageinfo_linux_p.h"
+
+#include "qdirlisting.h"
+#include <private/qcore_unix_p.h>
+#include <private/qtools_p.h>
+
+#include <q20memory.h>
+
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+
+// so we don't have to #include <linux/fs.h>, which is known to cause conflicts
+#ifndef FSLABEL_MAX
+#  define FSLABEL_MAX           256
+#endif
+#ifndef FS_IOC_GETFSLABEL
+#  define FS_IOC_GETFSLABEL     _IOR(0x94, 49, char[FSLABEL_MAX])
+#endif
+
+// or <linux/statfs.h>
+#ifndef ST_RDONLY
+#  define ST_RDONLY             0x0001  /* mount read-only */
+#endif
+
+#if defined(Q_OS_ANDROID)
+// statx() is disabled on Android because quite a few systems
+// come with sandboxes that kill applications that make system calls outside a
+// whitelist and several Android vendors can't be bothered to update the list.
+#  undef STATX_BASIC_STATS
+#endif
+
+QT_BEGIN_NAMESPACE
+
+using namespace Qt::StringLiterals;
+
+namespace {
+struct AutoFileDescriptor
+{
+    int fd = -1;
+    AutoFileDescriptor(const QString &path, int mode = QT_OPEN_RDONLY)
+        : fd(qt_safe_open(QFile::encodeName(path), mode))
+    {}
+    ~AutoFileDescriptor() { if (fd >= 0) qt_safe_close(fd); }
+    operator int() const noexcept { return fd; }
+};
+}
+
+// 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(QString &&str)
+{
+    using namespace QtMiscUtils;
+    qsizetype start = str.indexOf(u'\\');
+    if (start < 0)
+        return std::move(str);
+
+    // decode in-place
+    QString decoded = std::move(str);
+    auto ptr = reinterpret_cast<char16_t *>(decoded.begin());
+    qsizetype in = start;
+    qsizetype out = start;
+    qsizetype size = decoded.size();
+
+    while (in < size) {
+        Q_ASSERT(ptr[in] == u'\\');
+        if (size - in >= 4 && ptr[in + 1] == u'x') {    // we need four characters: \xAB
+            int c = fromHex(ptr[in + 2]) << 4;
+            c |= fromHex(ptr[in + 3]);
+            if (Q_UNLIKELY(c < 0))
+                c = QChar::ReplacementCharacter;        // bad hex sequence
+            ptr[out++] = c;
+            in += 4;
+        }
+
+        for ( ; in < size; ++in) {
+            char16_t c = ptr[in];
+            if (c == u'\\')
+                break;
+            ptr[out++] = c;
+        }
+    }
+    decoded.resize(out);
+    return decoded;
+}
+
+static inline dev_t deviceIdForPath(const QString &device)
+{
+    QT_STATBUF st;
+    if (QT_STAT(QFile::encodeName(device), &st) < 0)
+        return 0;
+    return st.st_dev;
+}
+
+static inline quint64 mountIdForPath(int fd)
+{
+    if (fd < 0)
+        return 0;
+#if defined(STATX_BASIC_STATS) && defined(STATX_MNT_ID)
+    // STATX_MNT_ID was added in kernel v5.8
+    struct statx st;
+    int r = statx(fd, "", AT_EMPTY_PATH | AT_NO_AUTOMOUNT, STATX_MNT_ID, &st);
+    if (r == 0 && (st.stx_mask & STATX_MNT_ID))
+        return st.stx_mnt_id;
+#endif
+    return 0;
+}
+
+static inline quint64 retrieveDeviceId(const QByteArray &device, quint64 deviceId = 0)
+{
+    // major = 0 implies an anonymous block device, so we need to stat() the
+    // actual device to get its dev_t. This is required for btrfs (and possibly
+    // others), which always uses them for all the subvolumes (including the
+    // root):
+    // https://codebrowser.dev/linux/linux/fs/btrfs/disk-io.c.html#btrfs_init_fs_root
+    // https://codebrowser.dev/linux/linux/fs/super.c.html#get_anon_bdev
+    // For everything else, we trust the parameter.
+    if (major(deviceId) != 0)
+        return deviceId;
+
+    // don't even try to stat() a relative path or "/"
+    if (device.size() < 2 || !device.startsWith('/'))
+        return 0;
+
+    QT_STATBUF st;
+    if (QT_STAT(device, &st) < 0)
+        return 0;
+    if (!S_ISBLK(st.st_mode))
+        return 0;
+    return st.st_rdev;
+}
+
+static QDirListing devicesByLabel()
+{
+    static const char pathDiskByLabel[] = "/dev/disk/by-label";
+    static constexpr auto LabelFileFilter =
+            QDir::AllEntries | QDir::System | QDir::Hidden | QDir::NoDotAndDotDot;
+
+    return QDirListing(QLatin1StringView(pathDiskByLabel), LabelFileFilter);
+}
+
+static inline auto retrieveLabels()
+{
+    struct Entry {
+        QString label;
+        quint64 deviceId;
+    };
+    QList<Entry> result;
+
+    for (const auto &dirEntry : devicesByLabel()) {
+        quint64 deviceId = retrieveDeviceId(QFile::encodeName(dirEntry.filePath()));
+        if (!deviceId)
+            continue;
+        result.emplaceBack(Entry{ decodeFsEncString(dirEntry.fileName()), deviceId });
+    }
+    return result;
+}
+
+static std::optional<QString> retrieveLabelViaIoctl(int fd)
+{
+    // FS_IOC_GETFSLABEL was introduced in v4.18; previously it was btrfs-specific.
+    if (fd < 0)
+        return std::nullopt;
+
+    // Note: it doesn't append the null terminator (despite what the man page
+    // says) and the return code on success (0) does not indicate the length.
+    char label[FSLABEL_MAX] = {};
+    int r = ioctl(fd, FS_IOC_GETFSLABEL, &label);
+    if (r < 0)
+        return std::nullopt;
+    return QString::fromUtf8(label);
+}
+
+static inline QString retrieveLabel(const QStorageInfoPrivate &d, int fd, quint64 deviceId)
+{
+    if (auto label = retrieveLabelViaIoctl(fd))
+        return *label;
+
+    deviceId = retrieveDeviceId(d.device, deviceId);
+    if (!deviceId)
+        return QString();
+
+    for (const auto &dirEntry : devicesByLabel()) {
+        if (retrieveDeviceId(QFile::encodeName(dirEntry.filePath())) == deviceId)
+            return decodeFsEncString(dirEntry.fileName());
+    }
+    return QString();
+}
+
+void QStorageInfoPrivate::retrieveVolumeInfo()
+{
+    struct statfs64 statfs_buf;
+    int result;
+    QT_EINTR_LOOP(result, statfs64(QFile::encodeName(rootPath).constData(), &statfs_buf));
+    if (result == 0) {
+        valid = true;
+        ready = true;
+
+        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;
+        blockSize = int(statfs_buf.f_bsize);
+        readOnly = (statfs_buf.f_flags & ST_RDONLY) != 0;
+    }
+}
+
+static std::vector<MountInfo> parseMountInfo(FilterMountInfo filter = FilterMountInfo::All)
+{
+    QFile file(u"/proc/self/mountinfo"_s);
+    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
+        return {};
+
+    QByteArray mountinfo = file.readAll();
+    file.close();
+
+    return doParseMountInfo(mountinfo, filter);
+}
+
+void QStorageInfoPrivate::doStat()
+{
+    retrieveVolumeInfo();
+    if (!ready)
+        return;
+
+    rootPath = QFileInfo(rootPath).canonicalFilePath();
+    if (rootPath.isEmpty())
+        return;
+
+    std::vector<MountInfo> infos = parseMountInfo();
+    if (infos.empty()) {
+        rootPath = u'/';
+        return;
+    }
+
+    MountInfo *best = nullptr;
+    AutoFileDescriptor fd(rootPath);
+    if (quint64 mntid = mountIdForPath(fd)) {
+        // We have the mount ID for this path, so find the matching line.
+        auto it = std::find_if(infos.begin(), infos.end(),
+                               [mntid](const MountInfo &info) { return info.mntid == mntid; });
+        if (it != infos.end())
+            best = q20::to_address(it);
+    } else {
+        // We have failed to get the mount ID for this path, usually because
+        // the path cannot be open()ed by this user (e.g., /root), so we fall
+        // back to a string search.
+        // We iterate over the /proc/self/mountinfo list backwards because then any
+        // matching isParentOf must be the actual mount point because it's the most
+        // recent mount on that path. Linux does allow mounting over non-empty
+        // directories, such as in:
+        //   # mount | tail -2
+        //   tmpfs on /tmp/foo/bar type tmpfs (rw,relatime,inode64)
+        //   tmpfs on /tmp/foo type tmpfs (rw,relatime,inode64)
+        //
+        // We try to match the device ID in case there's a mount --move.
+        // We can't *rely* on it because some filesystems like btrfs will assign
+        // device IDs to subvolumes that aren't listed in /proc/self/mountinfo.
+
+        const QString oldRootPath = std::exchange(rootPath, QString());
+        const dev_t rootPathDevId = deviceIdForPath(oldRootPath);
+        for (auto it = infos.rbegin(); it != infos.rend(); ++it) {
+            if (!isParentOf(it->mountPoint, oldRootPath))
+                continue;
+            if (rootPathDevId == it->stDev) {
+                // device ID matches; this is definitely the best option
+                best = q20::to_address(it);
+                break;
+            }
+            if (!best) {
+                // if we can't find a device ID match, this parent path is probably
+                // the correct one
+                best = q20::to_address(it);
+            }
+        }
+    }
+    if (best) {
+        auto stDev = best->stDev;
+        setFromMountInfo(std::move(*best));
+        name = retrieveLabel(*this, fd, stDev);
+    }
+}
+
+QList<QStorageInfo> QStorageInfoPrivate::mountedVolumes()
+{
+    std::vector<MountInfo> infos = parseMountInfo(FilterMountInfo::Filtered);
+    if (infos.empty())
+        return QList{root()};
+
+    std::optional<decltype(retrieveLabels())> labelMap;
+    auto labelForDevice = [&labelMap](const QStorageInfoPrivate &d, int fd, quint64 devid) {
+        if (d.fileSystemType == "tmpfs")
+            return QString();
+
+        if (auto label = retrieveLabelViaIoctl(fd))
+            return *label;
+
+        devid = retrieveDeviceId(d.device, devid);
+        if (!devid)
+            return QString();
+
+        if (!labelMap)
+            labelMap = retrieveLabels();
+        for (auto &[deviceLabel, deviceId] : std::as_const(*labelMap)) {
+            if (devid == deviceId)
+                return deviceLabel;
+        }
+        return QString();
+    };
+
+    QList<QStorageInfo> volumes;
+    volumes.reserve(infos.size());
+    for (auto it = infos.begin(); it != infos.end(); ++it) {
+        MountInfo &info = *it;
+        AutoFileDescriptor fd(info.mountPoint);
+
+        // find out if the path as we see it matches this line from mountinfo
+        quint64 mntid = mountIdForPath(fd);
+        if (mntid == 0) {
+            // statx failed, so scan the later lines to see if any is a parent
+            // to this
+            auto isParent = [&info](const MountInfo &maybeParent) {
+                return isParentOf(maybeParent.mountPoint, info.mountPoint);
+            };
+            if (std::find_if(it + 1, infos.end(), isParent) != infos.end())
+                continue;
+        } else if (mntid != info.mntid) {
+            continue;
+        }
+
+        const auto infoStDev = info.stDev;
+        QStorageInfoPrivate d(std::move(info));
+        d.retrieveVolumeInfo();
+        if (d.bytesTotal <= 0 && d.rootPath != u'/')
+            continue;
+        d.name = labelForDevice(d, fd, infoStDev);
+        volumes.emplace_back(QStorageInfo(*new QStorageInfoPrivate(std::move(d))));
+    }
+    return volumes;
+}
+
+QT_END_NAMESPACE