\inmodule QtCore More...

#include <qfiledevice.h>

Inheritance diagram for QFileDevice:

Collaboration diagram for QFileDevice:

Public Types
enum	FileError { NoError = 0 , ReadError = 1 , WriteError = 2 , FatalError = 3 , ResourceError = 4 , OpenError = 5 , AbortError = 6 , TimeOutError = 7 , UnspecifiedError = 8 , RemoveError = 9 , RenameError = 10 , PositionError = 11 , ResizeError = 12 , PermissionsError = 13 , CopyError = 14 }
	This enum describes the errors that may be returned by the error() function. More...

enum	FileTime { FileAccessTime , FileBirthTime , FileMetadataChangeTime , FileModificationTime }

enum	Permission { ReadOwner = 0x4000 , WriteOwner = 0x2000 , ExeOwner = 0x1000 , ReadUser = 0x0400 , WriteUser = 0x0200 , ExeUser = 0x0100 , ReadGroup = 0x0040 , WriteGroup = 0x0020 , ExeGroup = 0x0010 , ReadOther = 0x0004 , WriteOther = 0x0002 , ExeOther = 0x0001 }
	This enum is used by the permission() function to report the permissions and ownership of a file. More...

enum	FileHandleFlag { AutoCloseHandle = 0x0001 , DontCloseHandle = 0 }
	This enum is used when opening a file to specify additional options which only apply to files and not to a generic QIODevice. More...

enum	MemoryMapFlag { NoOptions = 0 , MapPrivateOption = 0x0001 }

Public Types inherited from QIODeviceBase
enum	OpenModeFlag { NotOpen = 0x0000 , ReadOnly = 0x0001 , WriteOnly = 0x0002 , ReadWrite = ReadOnly \| WriteOnly , Append = 0x0004 , Truncate = 0x0008 , Text = 0x0010 , Unbuffered = 0x0020 , NewOnly = 0x0040 , ExistingOnly = 0x0080 }
	This enum is used with QIODevice::open() to describe the mode in which a device is opened. More...

Public Member Functions
	~QFileDevice ()
	Destroys the file device, closing it if necessary.

FileError	error () const
	Returns the file error status.

void	unsetError ()
	Sets the file's error to QFileDevice::NoError.

void	close () override
	Calls QFileDevice::flush() and closes the file.

bool	isSequential () const override
	Returns `true` if the file can only be manipulated sequentially; otherwise returns `false`.

int	handle () const
	Returns the file handle of the file.

virtual QString	fileName () const
	Returns the name of the file.

qint64	pos () const override
	\reimp

bool	seek (qint64 offset) override
	For random-access devices, this function sets the current position to pos, returning true on success, or false if an error occurred.

bool	atEnd () const override
	Returns `true` if the end of the file has been reached; otherwise returns false.

bool	flush ()
	Flushes any buffered data to the file.

qint64	size () const override
	Returns the size of the file.

virtual bool	resize (qint64 sz)
	Sets the file size (in bytes) sz.

virtual Permissions	permissions () const
	Returns the complete OR-ed together combination of QFile::Permission for the file.

virtual bool	setPermissions (Permissions permissionSpec)
	Sets the permissions for the file to the permissions specified.

uchar *	map (qint64 offset, qint64 size, MemoryMapFlags flags=NoOptions)
	Maps size bytes of the file into memory starting at offset.

bool	unmap (uchar *address)
	Unmaps the memory address.

QDateTime	fileTime (QFileDevice::FileTime time) const

bool	setFileTime (const QDateTime &newDate, QFileDevice::FileTime fileTime)

Public Member Functions inherited from QIODevice
	QIODevice ()
	Constructs a QIODevice object.

	QIODevice (QObject *parent)
	Constructs a QIODevice object with the given parent.

virtual	~QIODevice ()
	The destructor is virtual, and QIODevice is an abstract base class.

QIODeviceBase::OpenMode	openMode () const
	Returns the mode in which the device has been opened; i.e.

void	setTextModeEnabled (bool enabled)
	If enabled is true, this function sets the \l Text flag on the device; otherwise the \l Text flag is removed.

bool	isTextModeEnabled () const
	Returns `true` if the \l Text flag is enabled; otherwise returns `false`.

bool	isOpen () const
	Returns `true` if the device is open; otherwise returns `false`.

bool	isReadable () const
	Returns `true` if data can be read from the device; otherwise returns false.

bool	isWritable () const
	Returns `true` if data can be written to the device; otherwise returns false.

int	readChannelCount () const

int	writeChannelCount () const

int	currentReadChannel () const

void	setCurrentReadChannel (int channel)

int	currentWriteChannel () const

void	setCurrentWriteChannel (int channel)

virtual bool	open (QIODeviceBase::OpenMode mode)
	Opens the device and sets its OpenMode to mode.

virtual bool	reset ()
	Seeks to the start of input for random-access devices.

virtual qint64	bytesAvailable () const
	Returns the number of bytes that are available for reading.

virtual qint64	bytesToWrite () const
	For buffered devices, this function returns the number of bytes waiting to be written.

qint64	read (char *data, qint64 maxlen)
	Reads at most maxSize bytes from the device into data, and returns the number of bytes read.

QByteArray	read (qint64 maxlen)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Reads at most maxSize bytes from the device, and returns the data read as a QByteArray.

QByteArray	readAll ()
	Reads all remaining data from the device, and returns it as a byte array.

qint64	readLine (char *data, qint64 maxlen)
	This function reads a line of ASCII characters from the device, up to a maximum of maxSize - 1 bytes, stores the characters in data, and returns the number of bytes read.

QByteArray	readLine (qint64 maxlen=0)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Reads a line from the device, but no more than maxSize characters, and returns the result as a byte array.

virtual bool	canReadLine () const
	Returns `true` if a complete line of data can be read from the device; otherwise returns `false`.

void	startTransaction ()

void	commitTransaction ()

void	rollbackTransaction ()

bool	isTransactionStarted () const

qint64	write (const char *data, qint64 len)
	Writes at most maxSize bytes of data from data to the device.

qint64	write (const char *data)

qint64	write (const QByteArray &data)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Writes the content of data to the device.

qint64	peek (char *data, qint64 maxlen)

QByteArray	peek (qint64 maxlen)

qint64	skip (qint64 maxSize)

virtual bool	waitForReadyRead (int msecs)
	Blocks until new data is available for reading and the readyRead() signal has been emitted, or until msecs milliseconds have passed.

virtual bool	waitForBytesWritten (int msecs)
	For buffered devices, this function waits until a payload of buffered written data has been written to the device and the bytesWritten() signal has been emitted, or until msecs milliseconds have passed.

void	ungetChar (char c)
	Puts the character c back into the device, and decrements the current position unless the position is 0.

bool	putChar (char c)
	Writes the character c to the device.

bool	getChar (char *c)
	Reads one character from the device and stores it in c.

QString	errorString () const
	Returns a human-readable description of the last device error that occurred.

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

virtual	~QObject ()
	Destroys the object, deleting all its child objects.

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.

bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).

QThread *	thread () const
	Returns the thread in which the object lives.

bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)
	Kills the timer with timer identifier, id.

void	killTimer (Qt::TimerId id)

template<typename T >
T	findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.

template<typename T >
T	findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const QObjectList &	children () const
	Returns a list of child objects.

void	setParent (QObject *parent)
	Makes the object a child of parent.

void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.

void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const

bool	disconnect (const QObject receiver, const char member=nullptr) const

void	dumpObjectTree () const
	Dumps a tree of children to the debug output.

void	dumpObjectInfo () const
	Dumps information about signal connections, etc.

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.

bool	setProperty (const char *name, QVariant &&value)

QVariant	property (const char *name) const
	Returns the value of the object's name property.

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const
	Returns a pointer to the parent object.

bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Protected Member Functions
	QFileDevice ()
	\macro QT_USE_NODISCARD_FILE_OPEN \macro QT_NO_USE_NODISCARD_FILE_OPEN

	QFileDevice (QObject *parent)

	QFileDevice (QFileDevicePrivate &dd, QObject *parent=nullptr)

qint64	readData (char *data, qint64 maxlen) override
	\reimp

qint64	writeData (const char *data, qint64 len) override
	\reimp

qint64	readLineData (char *data, qint64 maxlen) override
	\reimp

Protected Member Functions inherited from QIODevice
	QIODevice (QIODevicePrivate &dd, QObject *parent=nullptr)

virtual qint64	skipData (qint64 maxSize)

void	setOpenMode (QIODeviceBase::OpenMode openMode)
	Sets the OpenMode of the device to openMode.

void	setErrorString (const QString &errorString)
	Sets the human readable description of the last device error that occurred to str.

Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.

int	senderSignalIndex () const

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Protected Member Functions inherited from QIODeviceBase
	~QIODeviceBase ()=default

Related Symbols
(Note that these are not member symbols.)
	QFileDevice ()
	\macro QT_USE_NODISCARD_FILE_OPEN \macro QT_NO_USE_NODISCARD_FILE_OPEN

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Signals inherited from QIODevice
void	readyRead ()
	This signal is emitted once every time new data is available for reading from the device's current read channel.

void	channelReadyRead (int channel)

void	bytesWritten (qint64 bytes)
	This signal is emitted every time a payload of data has been written to the device's current write channel.

void	channelBytesWritten (int channel, qint64 bytes)

void	aboutToClose ()
	This signal is emitted when the device is about to close.

void	readChannelFinished ()

Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe

static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Properties inherited from QObject
QString	objectName
	the name of this object

Detailed Description

\inmodule QtCore

Since: 5.0

The QFileDevice class provides an interface for reading from and writing to open files.

\reentrant

QFileDevice is the base class for I/O devices that can read and write text and binary files and \l{The Qt Resource System}{resources}. QFile offers the main functionality, QFileDevice serves as a base class for sharing functionality with other file devices such as QSaveFile, by providing all the operations that can be done on files that have been opened by QFile or QSaveFile.

See also: QFile, QSaveFile

Definition at line 31 of file qfiledevice.h.

Member Enumeration Documentation

◆ FileError

enum QFileDevice::FileError

This enum describes the errors that may be returned by the error() function.

\value NoError No error occurred. \value ReadError An error occurred when reading from the file. \value WriteError An error occurred when writing to the file. \value FatalError A fatal error occurred. \value ResourceError Out of resources (e.g., too many open files, out of memory, etc.) \value OpenError The file could not be opened. \value AbortError The operation was aborted. \value TimeOutError A timeout occurred. \value UnspecifiedError An unspecified error occurred. \value RemoveError The file could not be removed. \value RenameError The file could not be renamed. \value PositionError The position in the file could not be changed. \value ResizeError The file could not be resized. \value PermissionsError The file could not be accessed. \value CopyError The file could not be copied.

Enumerator
NoError
ReadError
WriteError
FatalError
ResourceError
OpenError
AbortError
TimeOutError
UnspecifiedError
RemoveError
RenameError
PositionError
ResizeError
PermissionsError
CopyError

Definition at line 39 of file qfiledevice.h.

◆ FileHandleFlag

enum QFileDevice::FileHandleFlag

This enum is used when opening a file to specify additional options which only apply to files and not to a generic QIODevice.

\value AutoCloseHandle The file handle passed into open() should be closed by close(), the default behavior is that close just flushes the file and the application is responsible for closing the file handle. When opening a file by name, this flag is ignored as Qt always owns the file handle and must close it. \value DontCloseHandle If not explicitly closed, the underlying file handle is left open when the QFile object is destroyed.

Enumerator
AutoCloseHandle
DontCloseHandle

Definition at line 72 of file qfiledevice.h.

◆ FileTime

enum QFileDevice::FileTime

Since: 5.10

This enum is used by the fileTime() and setFileTime() functions.

\value FileAccessTime When the file was most recently accessed (e.g. read or written to). \value FileBirthTime When the file was created (may not be not supported on UNIX). \value FileMetadataChangeTime When the file's metadata was last changed. \value FileModificationTime When the file was most recently modified.

See also: setFileTime(), fileTime(), QFileInfo::fileTime()

Enumerator
FileAccessTime
FileBirthTime
FileMetadataChangeTime
FileModificationTime

Definition at line 57 of file qfiledevice.h.

◆ MemoryMapFlag

enum QFileDevice::MemoryMapFlag

Since: 4.4

This enum describes special options that may be used by the map() function.

\value NoOptions No options. \value MapPrivateOption The mapped memory will be private, so any modifications will not be visible to other processes and will not be written to disk. Any such modifications will be lost when the memory is unmapped. It is unspecified whether modifications made to the file made after the mapping is created will be visible through the mapped memory. This enum value was introduced in Qt 5.4.

Enumerator
NoOptions
MapPrivateOption

Definition at line 101 of file qfiledevice.h.

◆ Permission

enum QFileDevice::Permission

This enum is used by the permission() function to report the permissions and ownership of a file.

The values may be OR-ed together to test multiple permissions and ownership values.

\value ReadOwner The file is readable by the owner of the file. \value WriteOwner The file is writable by the owner of the file. \value ExeOwner The file is executable by the owner of the file. \value ReadUser The file is readable by the user. \value WriteUser The file is writable by the user. \value ExeUser The file is executable by the user. \value ReadGroup The file is readable by the group. \value WriteGroup The file is writable by the group. \value ExeGroup The file is executable by the group. \value ReadOther The file is readable by others. \value WriteOther The file is writable by others. \value ExeOther The file is executable by others.

Warning: Because of differences in the platforms supported by Qt, the semantics of ReadUser, WriteUser and ExeUser are platform-dependent: On Unix, the rights of the owner of the file are returned and on Windows the rights of the current user are returned. This behavior might change in a future Qt version.

Note: On NTFS file systems, ownership and permissions checking is disabled by default for performance reasons. To enable it, include the following line:

Permission checking is then turned on and off by incrementing and decrementing qt_ntfs_permission_lookup by 1.

qt_ntfs_permission_lookup++; // turn checking on

qt_ntfs_permission_lookup--; // turn it off again

Note: Since this is a non-atomic global variable, it is only safe to increment or decrement qt_ntfs_permission_lookup before any threads other than the main thread have started or after every thread other than the main thread has ended.; From Qt 6.6 the variable qt_ntfs_permission_lookup is deprecated. Please use the following alternatives.

The safe and easy way to manage permission checks is to use the RAII class QNtfsPermissionCheckGuard.

void complexFunction()
{
    QNtfsPermissionCheckGuard permissionGuard;  // check is enabled
 
    // do complex things here that need permission check enabled
 
}   // as the guard goes out of scope the check is disabled

If you need more fine-grained control, it is possible to manage the permission with the following functions instead:

qAreNtfsPermissionChecksEnabled();   // check status
qEnableNtfsPermissionChecks();       // turn checking on
qDisableNtfsPermissionChecks();      // turn it off again

Enumerator
ReadOwner
WriteOwner
ExeOwner
ReadUser
WriteUser
ExeUser
ReadGroup
WriteGroup
ExeGroup
ReadOther
WriteOther
ExeOther

Definition at line 64 of file qfiledevice.h.

Constructor & Destructor Documentation

◆ ~QFileDevice()

QFileDevice::~QFileDevice ( )

Destroys the file device, closing it if necessary.

Definition at line 236 of file qfiledevice.cpp.

References close().

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◆ QFileDevice() [1/3]

QFileDevice ( )

protected

\macro QT_USE_NODISCARD_FILE_OPEN \macro QT_NO_USE_NODISCARD_FILE_OPEN

Since: 6.8

File-related I/O classes (such as QFile, QSaveFile, QTemporaryFile) have an {open()} method to open the file they act upon. It is important to check the return value of the call to {open()} before proceeding with reading or writing data into the file.

For this reason, starting with Qt 6.8, some overloads of {open()} have been marked with the {[[nodiscard]]} attribute. Since this change may raise warnings in existing codebases, user code can opt-in or opt-out from having the attribute applied by defining certain macros:

\list

If the {QT_USE_NODISCARD_FILE_OPEN} macro is defined, overloads of {open()} are marked as {[[nodiscard]]}.
If the {QT_NO_USE_NODISCARD_FILE_OPEN} is defined, the overloads of {open()} are {not} marked as {[[nodiscard]]}.
If neither macro is defined, then the default up to and including Qt 6.9 is not to have the attribute. Starting from Qt 6.10, the attribute is automatically applied.
If both macros are defined, the program is ill-formed. \endlist

Definition at line 213 of file qfiledevice.cpp.

◆ QFileDevice() [2/3]

QFileDevice::QFileDevice ( QObject * parent )

explicitprotected

Definition at line 220 of file qfiledevice.cpp.

◆ QFileDevice() [3/3]

QFileDevice::QFileDevice	(	QFileDevicePrivate &	dd,
		QObject *	parent = nullptr )

protected

Definition at line 227 of file qfiledevice.cpp.

Member Function Documentation

◆ atEnd()

bool QFileDevice::atEnd ( ) const

overridevirtual

Returns true if the end of the file has been reached; otherwise returns false.

For regular empty files on Unix (e.g. those in /proc), this function returns true, since the file system reports that the size of such a file is 0. Therefore, you should not depend on atEnd() when reading data from such a file, but rather call read() until no more data can be read.

Reimplemented from QIODevice.

Definition at line 365 of file qfiledevice.cpp.

References QAbstractFileEngine::AtEndExtension, QIODevice::bytesAvailable(), d, QIODevice::isOpen(), and pos().

Referenced by QFile::copy(), QIBusPlatformInputContextPrivate::createConnection(), QBenchmarkValgrindUtils::extractResult(), getLibraryProjectsInOutputFolder(), QGeoFileTileCache::loadTiles(), lookupVendorIdInSystemDatabase(), noStream_snippet(), quick_test_main_with_setup(), QNetworkAccessFileBackend::read(), and QQmlJS::Dom::FileWriter::write().

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◆ close()

void QFileDevice::close ( )

overridevirtual

Calls QFileDevice::flush() and closes the file.

Errors from flush are ignored.

See also: QIODevice::close()

Reimplemented from QIODevice.

Definition at line 326 of file qfiledevice.cpp.

References QIODevice::close(), d, flush(), QIODevice::isOpen(), and unsetError().

Referenced by ~QFileDevice(), QGeoFileTileCache::~QGeoFileTileCache(), QGeoFileTileCache::addToDiskCache(), QNetworkAccessFileBackend::close(), QNetworkFile::close(), QTlsPrivate::TlsCryptographOpenSSL::continueHandshake(), QFile::copy(), QNetworkDiskCache::data(), QTranslatorPrivate::do_load(), FileContent(), QNetworkDiskCache::fileMetaData(), QGeoFileTileCache::getFromDisk(), QGeoFileTileCacheOsm::getFromOfflineStorage(), QQmlJSLinter::lintFile(), QGeoFileTileCache::loadTiles(), mergeGradleProperties(), QFile::moveToTrash(), MainWindow::openFile(), QQmlJSTypeReader::operator()(), QSSGQmlUtilities::outputTextureAsset(), parseMountInfo(), patchQtCore(), printError(), quick_test_main_with_setup(), QCacheUtils::readCookedMesh(), readGradleProperties(), QMimeBinaryProvider::CacheFile::reload(), QFile::remove(), QFile::rename(), QGtk3Json::save(), QFile::setFileName(), AudioOutputExample::stopAudioOutput(), AudioInputExample::stopRecording(), dom::DataTransfer::toMimeDataWithFile(), updateFile(), QNetworkAccessFileBackend::uploadReadyReadSlot(), QQmlJS::Dom::FileWriter::write(), QSSGQmlUtilities::writeQmlForAnimation(), and QQuickTextDocumentPrivate::writeTo().

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◆ error()

QFileDevice::FileError QFileDevice::error ( ) const

Returns the file error status.

The I/O device status returns an error code. For example, if open() returns false, or a read/write operation returns -1, this function can be called to find out the reason why the operation failed.

See also: unsetError()

Definition at line 586 of file qfiledevice.cpp.

References d.

Referenced by QNetworkReplyFileImpl::QNetworkReplyFileImpl(), QFile::copy(), QImageReaderPrivate::initHandler(), QQmlJSLinter::lintFile(), QFile::moveToTrash(), QNetworkFile::open(), QNetworkAccessFileBackend::read(), QFile::remove(), and QFile::rename().

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◆ fileName()

QString QFileDevice::fileName ( ) const

virtual

Returns the name of the file.

The default implementation in QFileDevice returns a null string.

Reimplemented in QFile.

Definition at line 280 of file qfiledevice.cpp.

◆ fileTime()

QDateTime QFileDevice::fileTime ( QFileDevice::FileTime time ) const

Since: 5.10 Returns the file time specified by time. If the time cannot be determined return QDateTime() (an invalid date time).

See also: setFileTime(), FileTime, QDateTime::isValid()

Definition at line 774 of file qfiledevice.cpp.

References d, and time.

Referenced by setFileTime().

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◆ flush()

bool QFileDevice::flush ( )

Flushes any buffered data to the file.

Returns true if successful; otherwise returns false.

Definition at line 289 of file qfiledevice.cpp.

References d, qWarning, UnspecifiedError, and WriteError.

Referenced by close(), QFileDevicePrivate::ensureFlushed(), QTextStreamPrivate::flushWriteBuffer(), QQmlDocumentFormatting::process(), QNetworkAccessFileBackend::uploadReadyReadSlot(), QImageWriter::write(), QQmlJS::Dom::FileWriter::write(), and writeData().

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◆ handle()

int QFileDevice::handle ( ) const

Returns the file handle of the file.

This is a small positive integer, suitable for use with C library functions such as fdopen() and fcntl(). On systems that use file descriptors for sockets (i.e. Unix systems, but not Windows) the handle can be used with QSocketNotifier as well.

If the file is not open, or there is an error, handle() returns -1.

See also: QSocketNotifier

Definition at line 267 of file qfiledevice.cpp.

References d, and QIODevice::isOpen().

Referenced by QTranslatorPrivate::do_load(), QTextStreamPrivate::fillReadBuffer(), and Decoder::setSource().

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◆ isSequential()

bool QFileDevice::isSequential ( ) const

overridevirtual

Returns true if the file can only be manipulated sequentially; otherwise returns false.

Most files support random-access, but some special files may not.

See also: QIODevice::isSequential()

Reimplemented from QIODevice.

Definition at line 249 of file qfiledevice.cpp.

References d.

Referenced by QNetworkAccessFileBackend::open(), QFile::open(), QFile::open(), QNetworkAccessFileBackend::read(), and QFile::rename().

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◆ map()

uchar * QFileDevice::map	(	qint64	offset,
		qint64	size,
		MemoryMapFlags	flags = NoOptions )

Maps size bytes of the file into memory starting at offset.

A file should be open for a map to succeed but the file does not need to stay open after the memory has been mapped. When the QFile is destroyed or a new file is opened with this object, any maps that have not been unmapped will automatically be unmapped.

The mapping will have the same open mode as the file (read and/or write), except when using MapPrivateOption, in which case it is always possible to write to the mapped memory.

Any mapping options can be passed through flags.

Returns a pointer to the memory or \nullptr if there is an error.

See also: unmap()

Definition at line 714 of file qfiledevice.cpp.

References d, QAbstractFileEngine::MapExtension, and unsetError().

Referenced by QIconCacheGtkReader::QIconCacheGtkReader(), findPatternUnloaded(), QMimeBinaryProvider::CacheFile::load(), qtiffMapProc(), QCacheUtils::readCookedMesh(), and readOrMapFile().

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◆ permissions()

QFile::Permissions QFileDevice::permissions ( ) const

virtual

Returns the complete OR-ed together combination of QFile::Permission for the file.

See also: setPermissions()

Reimplemented in QFile.

Definition at line 653 of file qfiledevice.cpp.

References d, and QAbstractFileEngine::PermsMask.

Referenced by QFile::permissions(), and setPermissions().

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◆ pos()

qint64 QFileDevice::pos ( ) const

overridevirtual

\reimp

Reimplemented from QIODevice.

Definition at line 351 of file qfiledevice.cpp.

References QIODevice::pos().

Referenced by atEnd(), QFile::open(), QFile::open(), ResourceIOStream::Seek(), and ResourceIOStream::Tell().

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◆ readData()

qint64 QFileDevice::readData	(	char *	data,
		qint64	maxlen )

overrideprotectedvirtual

\reimp

Implements QIODevice.

Definition at line 461 of file qfiledevice.cpp.

References d, QIODevice::read(), ReadError, unsetError(), and UnspecifiedError.

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◆ readLineData()

qint64 QFileDevice::readLineData	(	char *	data,
		qint64	maxlen )

overrideprotectedvirtual

\reimp

Reimplemented from QIODevice.

Definition at line 435 of file qfiledevice.cpp.

References d, QAbstractFileEngine::FastReadLineExtension, QIODevice::read(), and QIODevice::readLineData().

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◆ resize()

bool QFileDevice::resize ( qint64 sz )

virtual

Sets the file size (in bytes) sz.

Returns true if the resize succeeds; false otherwise. If sz is larger than the file currently is, the new bytes will be set to 0; if sz is smaller, the file is simply truncated.

Warning: This function can fail if the file doesn't exist.

See also: size()

Reimplemented in QFile.

Definition at line 629 of file qfiledevice.cpp.

References d, QIODevice::isOpen(), ResizeError, seek(), and unsetError().

Referenced by QFile::resize().

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◆ seek()

bool QFileDevice::seek ( qint64 pos )

overridevirtual

For random-access devices, this function sets the current position to pos, returning true on success, or false if an error occurred.

For sequential devices, the default behavior is to do nothing and return false.

Seeking beyond the end of a file: If the position is beyond the end of a file, then seek() will not immediately extend the file. If a write is performed at this position, then the file will be extended. The content of the file between the previous end of file and the newly written data is UNDEFINED and varies between platforms and file systems.

Reimplemented from QIODevice.

Definition at line 410 of file qfiledevice.cpp.

References d, QIODevice::isOpen(), PositionError, qWarning, QIODevice::seek(), unsetError(), and UnspecifiedError.

Referenced by QTranslatorPrivate::do_load(), QFile::open(), resize(), ResourceIOStream::Seek(), and QTextOdfWriter::writeInlineCharacter().

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◆ setFileTime()

bool QFileDevice::setFileTime	(	const QDateTime &	newDate,
		QFileDevice::FileTime	fileTime )

Since: 5.10 Sets the file time specified by fileTime to newDate, returning true if successful; otherwise returns false.

Note: The file must be open to use this function.

See also: fileTime(), FileTime

Definition at line 793 of file qfiledevice.cpp.

References d, fileTime(), tr, unsetError(), and UnspecifiedError.

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◆ setPermissions()

bool QFileDevice::setPermissions ( Permissions permissions )

virtual

Sets the permissions for the file to the permissions specified.

Returns true if successful, or false if the permissions cannot be modified.

Warning: This function does not manipulate ACLs, which may limit its effectiveness.

See also: permissions()

Reimplemented in QFile.

Definition at line 670 of file qfiledevice.cpp.

References d, permissions(), PermissionsError, and unsetError().

Referenced by QFile::setPermissions().

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◆ size()

qint64 QFileDevice::size ( ) const

overridevirtual

Returns the size of the file.

For regular empty files on Unix (e.g. those in /proc), this function returns 0; the contents of such a file are generated on demand in response to you calling read().

Reimplemented from QIODevice.

Definition at line 610 of file qfiledevice.cpp.

References d.

Referenced by QFile::size().

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◆ unmap()

bool QFileDevice::unmap ( uchar * address )

Unmaps the memory address.

Returns true if the unmap succeeds; false otherwise.

See also: map()

Definition at line 735 of file qfiledevice.cpp.

References d, PermissionsError, tr, QAbstractFileEngine::UnMapExtension, and unsetError().

Referenced by qtiffUnmapProc(), and QCacheUtils::readCookedMesh().

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◆ unsetError()

void QFileDevice::unsetError ( )

Sets the file's error to QFileDevice::NoError.

See also: error()

Definition at line 597 of file qfiledevice.cpp.

References d, and NoError.

Referenced by close(), QFile::copy(), QFile::link(), map(), QFile::moveToTrash(), QFile::open(), QFile::open(), QFile::open(), readData(), QFile::remove(), QFile::rename(), resize(), seek(), setFileTime(), setPermissions(), unmap(), and writeData().

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◆ writeData()

qint64 QFileDevice::writeData	(	const char *	data,
		qint64	len )

overrideprotectedvirtual

\reimp

Implements QIODevice.

Definition at line 546 of file qfiledevice.cpp.

References d, flush(), ret, QIODeviceBase::Unbuffered, unsetError(), UnspecifiedError, and WriteError.

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Friends And Related Symbol Documentation

◆ QFileDevice()

QFileDevice ( )

Since: 6.8

File-related I/O classes (such as QFile, QSaveFile, QTemporaryFile) have an {open()} method to open the file they act upon. It is important to check the return value of the call to {open()} before proceeding with reading or writing data into the file.

For this reason, starting with Qt 6.8, some overloads of {open()} have been marked with the {[[nodiscard]]} attribute. Since this change may raise warnings in existing codebases, user code can opt-in or opt-out from having the attribute applied by defining certain macros:

\list

If the {QT_USE_NODISCARD_FILE_OPEN} macro is defined, overloads of {open()} are marked as {[[nodiscard]]}.
If the {QT_NO_USE_NODISCARD_FILE_OPEN} is defined, the overloads of {open()} are {not} marked as {[[nodiscard]]}.
If neither macro is defined, then the default up to and including Qt 6.9 is not to have the attribute. Starting from Qt 6.10, the attribute is automatically applied.
If both macros are defined, the program is ill-formed. \endlist

Definition at line 213 of file qfiledevice.cpp.

The documentation for this class was generated from the following files:

qtbase/src/corelib/io/qfiledevice.h (7466831509fe163f3fd1e3a6bbf38f6f5a32ef00)
qtbase/src/corelib/io/qfiledevice.cpp (7466831509fe163f3fd1e3a6bbf38f6f5a32ef00)

Public Types

Public Member Functions

Protected Member Functions

Related Symbols

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ FileError

◆ FileHandleFlag

◆ FileTime

◆ MemoryMapFlag

◆ Permission

Constructor & Destructor Documentation

◆ ~QFileDevice()

◆ QFileDevice() [1/3]

◆ QFileDevice() [2/3]

◆ QFileDevice() [3/3]

Member Function Documentation

◆ atEnd()

◆ close()

◆ error()

◆ fileName()

◆ fileTime()

◆ flush()

◆ handle()

◆ isSequential()

◆ map()

◆ permissions()

◆ pos()

◆ readData()

◆ readLineData()

◆ resize()

◆ seek()

◆ setFileTime()

◆ setPermissions()

◆ size()

◆ unmap()

◆ unsetError()

◆ writeData()

Friends And Related Symbol Documentation

◆ QFileDevice()