The QAbstractFileEngine class provides an abstraction for accessing the file system. More...

Inheritance diagram for QAbstractFileEngine:

Classes
class	ExtensionOption
	Provides an extended input argument to QAbstractFileEngine's extension support More...

class	ExtensionReturn
	Provides an extended output argument to QAbstractFileEngine's extension support More...

class	MapExtensionOption
	Indicates a file engine supports the map() method More...

class	MapExtensionReturn
	Indicates a file engine which supports returning an address from the map() method More...

class	UnMapExtensionOption
	Indicates a file engine supports the unmap() method More...

Public Typedefs
using	FileFlags = QFlags< FileFlag >

Public Types
enum	Extension

enum	FileFlag

enum	FileName

enum	FileOwner

enum	FileTime

Public Methods
virtual	~QAbstractFileEngine ()

bool	atEnd () const

virtual QAbstractFileEngineIterator *	beginEntryList (QDir::Filters filters, const QStringList &filterNames)

virtual bool	caseSensitive () const

virtual bool	close ()

virtual bool	copy (const QString &newName)

virtual QStringList	entryList (QDir::Filters filters, const QStringList &filterNames) const

QFile::FileError	error () const

QString	errorString () const

virtual bool	extension (Extension extension, const ExtensionOption option=nullptr, ExtensionReturn output=nullptr)

virtual FileFlags	fileFlags (FileFlags type=FileInfoAll) const

virtual QString	fileName (FileName file=DefaultName) const

virtual QDateTime	fileTime (FileTime time) const

virtual bool	flush ()

virtual int	handle () const

virtual bool	isRelativePath () const

virtual bool	isSequential () const

virtual bool	link (const QString &newName)

uchar *	map (qint64 offset, qint64 size, QFile::MemoryMapFlags flags)

virtual bool	mkdir (const QString &dirName, bool createParentDirectories) const

virtual bool	open (QIODevice::OpenMode mode)

virtual QString	owner (FileOwner owner) const

virtual uint	ownerId (FileOwner owner) const

virtual qint64	pos () const

virtual qint64	read (char *data, qint64 maxlen)

virtual qint64	readLine (char *data, qint64 maxlen)

virtual bool	remove ()

virtual bool	rename (const QString &newName)

virtual bool	renameOverwrite (const QString &newName)

virtual bool	rmdir (const QString &dirName, bool recurseParentDirectories) const

virtual bool	seek (qint64 offset)

virtual void	setFileName (const QString &file)

virtual bool	setPermissions (uint perms)

virtual bool	setSize (qint64 size)

virtual qint64	size () const

virtual bool	supportsExtension (Extension extension) const

virtual bool	syncToDisk ()

bool	unmap (uchar *address)

virtual qint64	write (const char *data, qint64 len)

Static Public Methods
static QAbstractFileEngine *	create (const QString &fileName)

Protected Methods
	QAbstractFileEngine ()

void	setError (QFile::FileError error, const QString &errorString)

Detailed Description

The QAbstractFileEngine class provides an abstraction for accessing the file system.

The QDir, QFile, and QFileInfo classes all make use of a QAbstractFileEngine internally. If you create your own QAbstractFileEngine subclass (and register it with CopperSpice by creating a QAbstractFileEngineHandler subclass), your file engine will be used when the path is one that your file engine handles.

A QAbstractFileEngine refers to one file or one directory. If it a file, the setFileName(), rename(), and remove() methods are applicable. If it is a directory the mkdir(), rmdir(), and entryList() methods are applicable. In all cases the caseSensitive(), isRelativePath(), fileFlags(), ownerId(), owner(), and fileTime() methods are applicable.

A QAbstractFileEngine subclass can be created to do synchronous network I/O based file system operations, local file system operations, or to operate as a resource system to access file based resources.

See also: QAbstractFileEngineHandler

Member Typedef Documentation

QAbstractFileEngine::FileFlags

Typedef for QFlags<FileFlag> which contains an OR combination of FileFlag values.

Refer to QAbstractFileEngine::FileFlag for the enum documentation.

Member Enumeration Documentation

enum QAbstractFileEngine::Extension

This enum describes the types of extensions that the file engine can support. Before using these extensions, you must verify that the extension is supported (i.e., call supportsExtension()).

Constant	Value	Description
`QAbstractFileEngine::AtEndExtension`	`0`	Whether the current file position is at the end of the file or not. This extension allows file engines that implement local buffering to report end-of-file status without having to check the size of the file. It is also useful for sequential files, where the size of the file can not be used to determine whether or not you have reached the end. This extension returns true if the file is at the end, otherwise it returns false. The input and output arguments to extension() are ignored.
`QAbstractFileEngine::FastReadLineExtension`	`1`	Whether the file engine provides a fast implementation for readLine() or not. If readLine() remains unimplemented in the file engine, QAbstractFileEngine will provide an implementation based on calling read() repeatedly. If supportsExtension() returns false for this extension, however, QIODevice can provide a faster implementation by making use of its internal buffer. For engines that already provide a fast readLine() implementation, returning false for this extension can avoid unnecessary double-buffering in QIODevice.
`QAbstractFileEngine::MapExtension`	`2`	Whether the file engine provides the ability to map a file to memory.
`QAbstractFileEngine::UnMapExtension`	`3`	Whether the file engine provides the ability to unmap memory that was previously mapped.

enum QAbstractFileEngine::FileFlag

The permissions and types of a file which can be ORed together.

Constant	Value	Description
QAbstractFileEngine::ReadOwnerPerm	0x4000	Owner of the file has permission to read it.
QAbstractFileEngine::WriteOwnerPerm	0x2000	Owner of the file has permission to write to it.
QAbstractFileEngine::ExeOwnerPerm	0x1000	Owner of the file has permission to execute it.
QAbstractFileEngine::ReadUserPerm	0x0400	Current user has permission to read the file.
QAbstractFileEngine::WriteUserPerm	0x0200	Current user has permission to write to the file.
QAbstractFileEngine::ExeUserPerm	0x0100	Current user has permission to execute the file.
QAbstractFileEngine::ReadGroupPerm	0x0040	Members of the current user's group have permission to read the file.
QAbstractFileEngine::WriteGroupPerm	0x0020	Members of the current user's group have permission to write to the file.
QAbstractFileEngine::ExeGroupPerm	0x0010	Members of the current user's group have permission to execute the file.
QAbstractFileEngine::ReadOtherPerm	0x0004	All users have permission to read the file.
QAbstractFileEngine::WriteOtherPerm	0x0002	All users have permission to write to the file.
QAbstractFileEngine::ExeOtherPerm	0x0001	All users have permission to execute the file.
QAbstractFileEngine::LinkType	0x10000	File is a link to another file (or link) in the file system (i.e. not a file or directory).
QAbstractFileEngine::FileType	0x20000	File is a regular file to the file system (i.e. not a link or directory)
QAbstractFileEngine::BundleType	0x80000	File is a Mac OS X bundle implies DirectoryType
QAbstractFileEngine::DirectoryType	0x40000	File is a directory in the file system (i.e. not a link or file).
QAbstractFileEngine::HiddenFlag	0x0100000	File is hidden.
QAbstractFileEngine::ExistsFlag	0x0400000	File actually exists in the file system.
QAbstractFileEngine::RootFlag	0x0800000	File or the file pointed to is the root of the filesystem.
QAbstractFileEngine::LocalDiskFlag	0x0200000	File resides on the local disk and can be passed to standard file methods.
QAbstractFileEngine::Refresh	0x1000000	Passing this flag will force the file engine to refresh all flags.

See also: fileFlags(), setFileName()

enum QAbstractFileEngine::FileName

These values are used to request a file name in a particular format.

Constant	Value	Description
`QAbstractFileEngine::DefaultName`	`0`	Same filename that was passed to the QAbstractFileEngine.
`QAbstractFileEngine::BaseName`	`1`	Name of the file excluding the path.
`QAbstractFileEngine::PathName`	`2`	Path to the file excluding the base name.
`QAbstractFileEngine::AbsoluteName`	`3`	Absolute path to the file (including the base name).
`QAbstractFileEngine::AbsolutePathName`	`4`	Absolute path to the file (excluding the base name).
`QAbstractFileEngine::LinkName`	`5`	Full file name of the file this file is a link to, will be empty if this file is not a link
`QAbstractFileEngine::CanonicalName`	`6`	Often very similar to LinkName. Will return the true path to the file.
`QAbstractFileEngine::CanonicalPathName`	`7`	Same as CanonicalName, excluding the base name.
`QAbstractFileEngine::BundleName`	`8`	Returns the name of the bundle implies BundleType is set.

See also: fileName(), setFileName()

enum QAbstractFileEngine::FileOwner

Constant	Value	Description
`QAbstractFileEngine::OwnerUser`	`0`	User who owns the file.
`QAbstractFileEngine::OwnerGroup`	`1`	Group who owns the file.

See also: owner(), ownerId(), setFileName()

enum QAbstractFileEngine::FileTime

These are used by the fileTime() method.

Constant	Value	Description
`QAbstractFileEngine::CreationTime`	`0`	When the file was created.
`QAbstractFileEngine::ModificationTime`	`1`	When the file was most recently modified.
`QAbstractFileEngine::AccessTime`	`2`	When the file was most recently accessed (e.g. read or written to).

See also: setFileName()

Constructor & Destructor Documentation

QAbstractFileEngine::~QAbstractFileEngine ( )

virtual

Destroys the QAbstractFileEngine.

QAbstractFileEngine::QAbstractFileEngine ( )

protected

Constructs a new QAbstractFileEngine that does not refer to any file or directory.

See also: setFileName()

Method Documentation

bool QAbstractFileEngine::atEnd ( ) const

Returns true if the current position is at the end of the file, otherwise returns false. This method calls extension() with AtEndExtension. If the engine does not support this extension, false is returned.

See also: extension(), supportsExtension(), QFile::atEnd()

QAbstractFileEngineIterator * QAbstractFileEngine::beginEntryList	(	QDir::Filters	filters,
		const QStringList &	filterNames
	)

virtual

Returns an instance of QAbstractFileEngineIterator using filters for entry filtering and filterNames for name filtering. This method is called by QDirIterator to initiate directory iteration. The caller takes ownership of the returned instance and must delete it.

See also: QDirIterator

Reimplemented in QFSFileEngine::beginEntryList()

bool QAbstractFileEngine::caseSensitive ( ) const

virtual

Should return true if the underlying file system is case-sensitive, otherwise return false.

Reimplemented in QFSFileEngine::caseSensitive()

bool QAbstractFileEngine::close ( )

virtual

Closes the file, returning true if successful, otherwise returns false. The default implementation always returns false.

Reimplemented in QFSFileEngine::close()

bool QAbstractFileEngine::copy ( const QString & newName )

virtual

Copies the contents of this file to a file with the name newName. Returns true on success, otherwise false is returned.

Reimplemented in QFSFileEngine::copy()

QAbstractFileEngine * QAbstractFileEngine::create ( const QString & fileName )

static

Creates and returns a QAbstractFileEngine suitable for processing fileName. You should not need to call this method, use QFile, QFileInfo or QDir directly instead. If you reimplement this method it should only return file engines that knows how to handle fileName, otherwise it should return nullptr.

See also: QAbstractFileEngineHandler

QStringList QAbstractFileEngine::entryList	(	QDir::Filters	filters,
		const QStringList &	filterNames
	)		const

virtual

Requests that a list of all the files matching the filters list based on the filterNames in the file engine's directory are returned. This method should return an empty list if the file engine refers to a file rather than a directory, or if the directory is unreadable or does not exist or if nothing matches the specifications.

See also: setFileName()

Reimplemented in QFSFileEngine::entryList()

QFile::FileError QAbstractFileEngine::error ( ) const

Returns the QFile::FileError that resulted from the last failed operation. If QFile::UnspecifiedError is returned, QFile will use its own idea of the error status.

See also: setError(), QFile::FileError, errorString()

QString QAbstractFileEngine::errorString ( ) const

Returns the human readable message appropriate to the current error reported by error(). If no suitable string is available, an empty string is returned.

See also: error()

bool QAbstractFileEngine::extension	(	Extension	extension,
		const ExtensionOption *	option = `nullptr`,
		ExtensionReturn *	output = `nullptr`
	)

virtual

This method can be reimplemented in a QAbstractFileEngine subclass to provide support for extensions. The option argument is provided as input to the extension and this methods can store output results in output.

The behavior of this method is determined by extension. You can call supportsExtension() to check if an extension is supported by the file engine. By default, no extensions are supported and this method returns false.

See also: supportsExtension(), Extension

FileFlags QAbstractFileEngine::fileFlags ( FileFlags type = FileInfoAll ) const

virtual

This method should return the set of flags which are true for the current file and also are set in the given type. In your reimplementation use the type argument as an optimization hint.

See also: setFileName()

Reimplemented in QFSFileEngine::fileFlags()

QString QAbstractFileEngine::fileName ( FileName file = DefaultName ) const

virtual

Return the file engine's current file name in the format specified by file. If you do not handle some FileName possibilities, return the file name set in setFileName() when an unhandled format is requested.

See also: setFileName(), FileName

Reimplemented in QFSFileEngine::fileName()

QDateTime QAbstractFileEngine::fileTime ( FileTime time ) const

virtual

If time is CreationTime, returns when the file was created. If time is ModificationTime, returns when the file was most recently modified. If time is AccessTime, returns when the file was most recently accessed (e.g. read or written). If the time can not be determined returns an invalid QDateTime().

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

Reimplemented in QFSFileEngine::fileTime()

bool QAbstractFileEngine::flush ( )

virtual

Flushes the open file, returning true if successful, otherwise returns false. The default implementation always returns false.

Reimplemented in QFSFileEngine::flush()

int QAbstractFileEngine::handle ( ) const

virtual

Returns the native file handle for this file engine. This handle must be used with care since its value and type are platform specific. Using this method can lead to non-portable code.

Reimplemented in QFSFileEngine::handle()

bool QAbstractFileEngine::isRelativePath ( ) const

virtual

Return true if the file referred to by this file engine has a relative path, otherwise return false.

See also: setFileName()

Reimplemented in QFSFileEngine::isRelativePath()

bool QAbstractFileEngine::isSequential ( ) const

virtual

Returns true if the file is a sequential access device; returns false if the file is a direct access device. Operations involving size() and seek(int) are not valid on sequential devices.

Reimplemented in QFSFileEngine::isSequential()

bool QAbstractFileEngine::link ( const QString & newName )

virtual

Creates a link from the file currently specified by fileName() to newName. What a link is depends on the underlying file system (be it a shortcut on Windows or a symbolic link on Unix). Returns true if successful, otherwise returns false.

Reimplemented in QFSFileEngine::link()

uchar * QAbstractFileEngine::map	(	qint64	offset,
		qint64	size,
		QFile::MemoryMapFlags	flags
	)

Maps size bytes of the file into memory starting at offset. Returns a pointer to the memory when successful, otherwise returns false if for example, an error occurs. This method bases its behavior on calling extension() with MapExtensionOption. If the engine does not support this extension a nullptr is returned.

The parameter flags is currently not used.

See also: unmap(), supportsExtension()

bool QAbstractFileEngine::mkdir	(	const QString &	dirName,
		bool	createParentDirectories
	)		const

virtual

Requests that the directory dirName be created. If createParentDirectories is true, then any sub-directories in dirName that do not exist must be created. If createParentDirectories is false then any sub-directories in dirName must already exist for the method to succeed. If the operation succeeds return true, otherwise return false.

See also: setFileName(), rmdir(), isRelativePath()

Reimplemented in QFSFileEngine::mkdir()

bool QAbstractFileEngine::open ( QIODevice::OpenMode mode )

virtual

Opens the file in the specified mode. Returns true if the file was successfully opened, otherwise returns false. The mode is an OR combination of QIODevice::OpenMode and QIODevice::HandlingMode values.

Reimplemented in QFSFileEngine::open()

QString QAbstractFileEngine::owner ( FileOwner owner ) const

virtual

If owner is OwnerUser return the name of the user who owns the file. If owner is OwnerGroup return the name of the group that own the file. If you can not determine the owner return QString().

See also: ownerId(), setFileName(), FileOwner

Reimplemented in QFSFileEngine::owner()

uint QAbstractFileEngine::ownerId ( FileOwner owner ) const

virtual

If owner is OwnerUser return the ID of the user who owns the file. If owner is OwnerGroup return the ID of the group that own the file. If you can not determine the owner return -2.

See also: owner(), setFileName(), FileOwner

Reimplemented in QFSFileEngine::ownerId()

qint64 QAbstractFileEngine::pos ( ) const

virtual

Returns the current file position. This is the position of the data read/write head of the file.

Reimplemented in QFSFileEngine::pos()

qint64 QAbstractFileEngine::read	(	char *	data,
		qint64	maxlen
	)

virtual

Reads a number of characters from the file into data. At most maxlen characters will be read. Returns -1 if a fatal error occurs or 0 if there are no bytes to read.

Reimplemented in QFSFileEngine::read()

qint64 QAbstractFileEngine::readLine	(	char *	data,
		qint64	maxlen
	)

virtual

This method reads one line, terminated by a '\n' character, from the file info data. At most maxlen characters will be read. The end-of-line character is included.

Reimplemented in QFSFileEngine::readLine()

bool QAbstractFileEngine::remove ( )

virtual

Requests that the file is deleted from the file system. If the operation succeeds return true, otherwise return false.

See also: setFileName(), rmdir()

Reimplemented in QFSFileEngine::remove()

bool QAbstractFileEngine::rename ( const QString & newName )

virtual

Requests that the file be renamed to newName in the file system. If the operation succeeds the method returns true, otherwise returns false.

See also: setFileName()

Reimplemented in QFSFileEngine::rename()

bool QAbstractFileEngine::renameOverwrite ( const QString & newName )

virtual

Requests that the file be renamed to newName in the file system. If the new name already exists, it must be overwritten. If the operation succeeds the method returns true, otherwise returns false.

See also: setFileName()

Reimplemented in QFSFileEngine::renameOverwrite()

bool QAbstractFileEngine::rmdir	(	const QString &	dirName,
		bool	recurseParentDirectories
	)		const

virtual

Requests that the directory dirName is deleted from the file system. When recurseParentDirectories is true, then any empty parent-directories in dirName must also be deleted. If recurseParentDirectories is false, only the dirName leaf-node should be deleted. In most file systems a directory can not be deleted using this method if it is non-empty. If the operation succeeds return true, otherwise return false.

See also: setFileName(), remove(), mkdir(), isRelativePath()

Reimplemented in QFSFileEngine::rmdir()

bool QAbstractFileEngine::seek ( qint64 offset )

virtual

Sets the file position to the given offset. Returns true if the position was successfully set, otherwise returns false. The offset is from the beginning of the file, unless the file is sequential.

See also: isSequential()

Reimplemented in QFSFileEngine::seek()

void QAbstractFileEngine::setError	(	QFile::FileError	error,
		const QString &	errorString
	)

protected

Sets the error type to error, and the error string to errorString. Call this method to set the error values returned by the higher-level classes.

See also: QFile::error(), QIODevice::errorString(), QIODevice::setErrorString()

void QAbstractFileEngine::setFileName ( const QString & file )

virtual

Sets the file engine's file name to file. This file name is the file that the rest of the methods will operate on.

See also: fileName(), rename()

Reimplemented in QFSFileEngine::setFileName()

bool QAbstractFileEngine::setPermissions ( uint perms )

virtual

Requests that the file's permissions be set to perms. The argument perms will be set to the OR-ed together combination of QAbstractFileEngine::FileInfo, with only the QAbstractFileEngine::PermsMask being honored. If the operations succeeds return true, otherwise return false.

See also: size()

Reimplemented in QFSFileEngine::setPermissions()

bool QAbstractFileEngine::setSize ( qint64 size )

virtual

Requests the file be set to size. If size is larger than the current file then it is filled with zeros, if smaller it is simply truncated. If the operations succeeds return true, otherwise return false.

See also: size()

Reimplemented in QFSFileEngine::setSize()

qint64 QAbstractFileEngine::size ( ) const

virtual

Returns the size of the file.

See also: setSize()

Reimplemented in QFSFileEngine::size()

bool QAbstractFileEngine::supportsExtension ( Extension extension ) const

virtual

This method returns true if the file engine supports extension, otherwise false is returned. By default, no extensions are supported.

See also: extension()

Reimplemented in QFSFileEngine::supportsExtension()

bool QAbstractFileEngine::syncToDisk ( )

virtual

Flushes and syncs the file to disk. Returns true if successful, otherwise returns false. The default implementation always returns false.

Reimplemented in QFSFileEngine::syncToDisk()

bool QAbstractFileEngine::unmap ( uchar * address )

Unmaps the memory address. Returns true if the unmap succeeds, otherwise returns false. This method bases its behavior on calling extension() with UnMapExtensionOption. If the engine does not support this extension, false is returned.

See also: map(), supportsExtension()

qint64 QAbstractFileEngine::write	(	const char *	data,
		qint64	len
	)

virtual

Writes len bytes from data to the file. Returns the number of characters written on success, otherwise returns -1.

Reimplemented in QFSFileEngine::write()

Classes

Public Typedefs

Public Types

Public Methods

Static Public Methods

Protected Methods

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Method Documentation