- Qt 6.8
- Qt Core
- C++ Classes
- QStorageInfo
- Qt 6.8.3 Reference Documentation

# QStorageInfo Class

Provides information about currently mounted storage and drives. More...

Header: | `#include <QStorageInfo>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Core)` `target_link_libraries(mytarget PRIVATE Qt6::Core)`
qmake: | `QT += core`

- List of all members, including inherited members
- QStorageInfo is part of Input/Output and Networking and Implicitly Shared Classes.

This class is equality-comparable.

## Public Functions

| QStorageInfo()
| QStorageInfo(const QDir &dir)
| QStorageInfo(const QString &path)
| QStorageInfo(const QStorageInfo &other)
| ~QStorageInfo()
int | blockSize() const
qint64 | bytesAvailable() const
qint64 | bytesFree() const
qint64 | bytesTotal() const
QByteArray | device() const
QString | displayName() const
QByteArray | fileSystemType() const
bool | isReadOnly() const
bool | isReady() const
bool | isRoot() const
bool | isValid() const
QString | name() const
void | refresh()
QString | rootPath() const
void | setPath(const QString &path)
QByteArray | subvolume() const
void | swap(QStorageInfo &other)
QStorageInfo & | operator=(QStorageInfo &&other)
QStorageInfo & | operator=(const QStorageInfo &other)

## Static Public Members

QList<QStorageInfo> | mountedVolumes()
QStorageInfo | root()

## Related Non-Members

bool | operator!=(const QStorageInfo &lhs, const QStorageInfo &rhs)
bool | operator==(const QStorageInfo &lhs, const QStorageInfo &rhs)

## Detailed Description

Allows retrieving information about the volume's space, its mount point, label, and filesystem name.

You can create an instance of QStorageInfo by passing the path to the volume's mount point as a constructor parameter, or you can set it using the setPath() method. The static mountedVolumes() method can be used to get the list of all mounted filesystems.

QStorageInfo always caches the retrieved information, but you can call refresh() to invalidate the cache.

The following example retrieves the most common information about the root volume of the system, and prints information about it.

         QStorageInfo storage = QStorageInfo::root();

         qDebug() << storage.rootPath();
         if (storage.isReadOnly())
             qDebug() << "isReadOnly:" << storage.isReadOnly();

         qDebug() << "name:" << storage.name();
         qDebug() << "fileSystemType:" << storage.fileSystemType();
         qDebug() << "size:" << storage.bytesTotal()/1000/1000 << "MB";
         qDebug() << "availableSize:" << storage.bytesAvailable()/1000/1000 << "MB";

## Member Function Documentation

### QStorageInfo::QStorageInfo()

Constructs an empty QStorageInfo object.

Objects created with the default constructor will be invalid and therefore not ready for use.

See also setPath(), isReady(), and isValid().

### `[explicit]` QStorageInfo::QStorageInfo(const QDir &dir)

Constructs a new QStorageInfo object that gives information about the volume containing the dir folder.

### `[explicit]` QStorageInfo::QStorageInfo(const QString &path)

Constructs a new QStorageInfo object that gives information about the volume mounted at path.

If you pass a directory or file, the QStorageInfo object will refer to the volume where this directory or file is located. You can check if the created object is correct using the isValid() method.

The following example shows how to get the volume on which the application is located. It is recommended to always check that the volume is ready and valid.

         QStorageInfo storage(qApp->applicationDirPath());
         if (storage.isValid() && storage.isReady()) {
             // ...
         }

See also setPath().

### QStorageInfo::QStorageInfo(const QStorageInfo &other)

Constructs a new QStorageInfo object that is a copy of the other QStorageInfo object.

### `[noexcept]` QStorageInfo::~QStorageInfo()

Destroys the QStorageInfo object and frees its resources.

### int QStorageInfo::blockSize() const

Returns the optimal transfer block size for this filesystem.

Returns -1 if QStorageInfo could not determine the size or if the QStorageInfo object is not valid.

### qint64 QStorageInfo::bytesAvailable() const

Returns the size (in bytes) available for the current user. It returns the total size available if the user is the root user or a system administrator.

This size can be less than or equal to the free size returned by bytesFree() function.

Returns -1 if QStorageInfo object is not valid.

See also bytesTotal() and bytesFree().

### qint64 QStorageInfo::bytesFree() const

Returns the number of free bytes in a volume. Note that if there are quotas on the filesystem, this value can be larger than the value returned by bytesAvailable().

Returns -1 if QStorageInfo object is not valid.

See also bytesTotal() and bytesAvailable().

### qint64 QStorageInfo::bytesTotal() const

Returns the total volume size in bytes.

Returns -1 if QStorageInfo object is not valid.

See also bytesFree() and bytesAvailable().

### QByteArray QStorageInfo::device() const

Returns the device for this volume.

For example, on Unix filesystems (including macOS), this returns the devpath like `/dev/sda0` for local storages. On Windows, it returns the UNC path starting with `\\\\?\\` for local storages (in other words, the volume GUID).

See also rootPath() and subvolume().

### QString QStorageInfo::displayName() const

Returns the volume's name, if available, or the root path if not.

### QByteArray QStorageInfo::fileSystemType() const

Returns the type name of the filesystem.

This is a platform-dependent function, and filesystem names can vary between different operating systems. For example, on Windows filesystems they can be named `NTFS`, and on Linux they can be named `ntfs-3g` or `fuseblk`.

See also name().

### bool QStorageInfo::isReadOnly() const

Returns true if the current filesystem is protected from writing; false otherwise.

### bool QStorageInfo::isReady() const

Returns true if the current filesystem is ready to work; false otherwise. For example, false is returned if the CD volume is not inserted.

Note that fileSystemType(), name(), bytesTotal(), bytesFree(), and bytesAvailable() will return invalid data until the volume is ready.

See also isValid().

### bool QStorageInfo::isRoot() const

Returns true if this QStorageInfo represents the system root volume; false otherwise.

On Unix filesystems, the root volume is a volume mounted on `/`. On Windows, the root volume is the volume where the OS is installed.

See also root().

### bool QStorageInfo::isValid() const

Returns true if the QStorageInfo specified by rootPath exists and is mounted correctly.

See also isReady().

### `[static]` QList<QStorageInfo> QStorageInfo::mountedVolumes()

Returns the list of QStorageInfo objects that corresponds to the list of currently mounted filesystems.

On Windows, this returns the drives visible in the My Computer folder. On Unix operating systems, it returns the list of all mounted filesystems (except for pseudo filesystems).

Returns all currently mounted filesystems by default.

The example shows how to retrieve all available filesystems, skipping read-only ones.

         foreach (const QStorageInfo &storage, QStorageInfo::mountedVolumes()) {
             if (storage.isValid() && storage.isReady()) {
                 if (!storage.isReadOnly()) {
                     // ...
                 }
             }
         }

See also root().

### QString QStorageInfo::name() const

Returns the human-readable name of a filesystem, usually called `label`.

Not all filesystems support this feature. In this case, the value returned by this method could be empty. An empty string is returned if the file system does not support labels, or if no label is set.

On Linux, retrieving the volume's label requires `udev` to be present in the system.

See also fileSystemType().

### void QStorageInfo::refresh()

Resets QStorageInfo's internal cache.

QStorageInfo caches information about storage to speed up performance. QStorageInfo retrieves information during object construction and/or when calling the setPath() method. You have to manually reset the cache by calling this function to update storage information.

### `[static]` QStorageInfo QStorageInfo::root()

Returns a QStorageInfo object that represents the system root volume.

On Unix systems this call returns the root ('/') volume; in Windows the volume where the operating system is installed.

See also isRoot().

### QString QStorageInfo::rootPath() const

Returns the mount point of the filesystem this QStorageInfo object represents.

On Windows, it returns the volume letter in case the volume is not mounted to a directory.

Note that the value returned by rootPath() is the real mount point of a volume, and may not be equal to the value passed to the constructor or setPath() method. For example, if you have only the root volume in the system, and pass '/directory' to setPath(), then this method will return '/'.

See also setPath() and device().

### void QStorageInfo::setPath(const QString &path)

Sets this QStorageInfo object to the filesystem mounted where path is located.

path can either be a root path of the filesystem, a directory, or a file within that filesystem.

See also rootPath().

### QByteArray QStorageInfo::subvolume() const

Returns the subvolume name for this volume.

Some filesystem types allow multiple subvolumes inside one device, which may be mounted in different paths (e.g. 'bind' mounts on Unix, or Btrfs filesystem subvolumes). If the subvolume could be detected, its name is returned by this function. The format of the subvolume name is specific to each filesystem type.

If this volume was not mounted from a subvolume of a larger filesystem or if the subvolume could not be detected, this function returns an empty byte array.

See also device().

### `[noexcept]` void QStorageInfo::swap(QStorageInfo &other)

Swaps this volume info with other. This operation is very fast and never fails.

### `[noexcept]` QStorageInfo &QStorageInfo::operator=(QStorageInfo &&other)

Assigns other to this QStorageInfo instance.

### QStorageInfo &QStorageInfo::operator=(const QStorageInfo &other)

Makes a copy of the QStorageInfo object other and assigns it to this QStorageInfo object.

## Related Non-Members

### `[noexcept]` bool operator!=(const QStorageInfo &lhs, const QStorageInfo &rhs)

Returns `true` if the QStorageInfo object lhs refers to a different drive or volume than the QStorageInfo object rhs; otherwise returns `false`.

### `[noexcept]` bool operator==(const QStorageInfo &lhs, const QStorageInfo &rhs)

Returns `true` if the QStorageInfo object lhs refers to the same drive or volume as the QStorageInfo object rhs; otherwise it returns `false`.

Note that the result of comparing two invalid QStorageInfo objects is always positive.