The QAbstractFileEngine is a base class 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

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 (QFileDevice::FileTimeType type) 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	setFileTime (const QDateTime &newTime, QFileDevice::FileTimeType type)

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

This is a base class abstraction for accessing the file system.

The QDir, QFile, and QFileInfo classes will call methods in QAbstractFileEngine. To change the behavior of these classes create a new class which inherits from QAbstractFileEngine. To use your custom file engine, you will need to register your new class with CopperSpice by inheriting from QAbstractFileEngineHandler.

The design of QAbstractFileEngine is to refer to a single file or directory. The main file methods include setFileName(), rename(), and remove(). The methods for a directory are mkdir(), rmdir(), and entryList(). The methods caseSensitive(), isRelativePath(), fileFlags(), ownerId(), owner(), and fileTime() apply to both files and directories.

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 the file engine can support. Before using an extension verify it is supported by calling supportsExtension().

Constant	Value	Description
`QAbstractFileEngine::AtEndExtension`	`0`	Test if the current file position is at the end of the file. This extension allows file engines with local buffering to report end-of-file status without checking the file size. It is useful for sequential files where the size of the file can not be used to determine whether or not you have reached the end. Calling extension() with this value returns true if the current position is at the end of the file, otherwise it returns false.
`QAbstractFileEngine::FastReadLineExtension`	`1`	Test if the file engine provides a fast implementation for readLine(). If readLine() is not implemented in the file engine, QAbstractFileEngine will provide a default implementation based on calling read() repeatedly. If supportsExtension() returns false for this value QIODevice can provide a faster implementation by making use of its internal buffer. For engines which provide a fast readLine() implementation, returning false for this extension can avoid unnecessary double-buffering in QIODevice.
`QAbstractFileEngine::MapExtension`	`2`	File engine has the ability to map a file into memory.
`QAbstractFileEngine::UnMapExtension`	`3`	File engine provides the ability to unmap memory which 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
QAbstractFileEngine::WriteOwnerPerm	0x2000	Owner of the file has permission to write
QAbstractFileEngine::ExeOwnerPerm	0x1000	Owner of the file has permission to execute
QAbstractFileEngine::ReadUserPerm	0x0400	Current user has permission to read
QAbstractFileEngine::WriteUserPerm	0x0200	Current user has permission to write
QAbstractFileEngine::ExeUserPerm	0x0100	Current user has permission to execute
QAbstractFileEngine::ReadGroupPerm	0x0040	Members of the current user's group have permission to read
QAbstractFileEngine::WriteGroupPerm	0x0020	Members of the current user's group have permission to write
QAbstractFileEngine::ExeGroupPerm	0x0010	Members of the current user's group have permission to execute
QAbstractFileEngine::ReadOtherPerm	0x0004	All users have permission to read
QAbstractFileEngine::WriteOtherPerm	0x0002	All users have permission to write
QAbstractFileEngine::ExeOtherPerm	0x0001	All users have permission to execute
QAbstractFileEngine::LinkType	0x10000	File is a link to another file or link
QAbstractFileEngine::FileType	0x20000	File is a regular file, not a link or a directory
QAbstractFileEngine::BundleType	0x80000	File is a Mac OS X bundle
QAbstractFileEngine::DirectoryType	0x40000	File is a directory in the file system, not a file or a link
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 which 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 target of this link, empty if this file is not a link
`QAbstractFileEngine::CanonicalName`	`6`	Often very similar to LinkName, will return the canonical path to the file
`QAbstractFileEngine::CanonicalPathName`	`7`	Same as CanonicalName, excluding the base name
`QAbstractFileEngine::BundleName`	`8`	Returns the name of the bundle

See also: fileName(), setFileName()

enum QAbstractFileEngine::FileOwner

An enum which indicates information about the owner of a file.

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

See also: owner(), ownerId()

Constructor & Destructor Documentation

QAbstractFileEngine::~QAbstractFileEngine ( )

virtual

Destroys the current QAbstractFileEngine.

QAbstractFileEngine::QAbstractFileEngine ( )

protected

Constructs a new QAbstractFileEngine which does not refer to any specific 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 the enum AtEndExtension. If the current QAbstractFileEngine does not support this extension, false will be returned.

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

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

virtual

Returns a pointer to a QAbstractFileEngineIterator. Only files matching filters and filterNames will be part of the list. The caller is the owner of the iterator and is responsible for deleting it.

See also: QDirIterator

Reimplemented in QFSFileEngine::beginEntryList()

bool QAbstractFileEngine::caseSensitive ( ) const

virtual

This method returns 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 the current 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 for processing fileName. Normally, this method should not be called. Prefer using methods in QFile, QFileInfo or QDir.

When overriding this method only return a file engine which can handle the given fileName, otherwise it should return a nullptr.

See also: QAbstractFileEngineHandler

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

virtual

Returns a list of all files matching filters based on the filterNames in the current QAbstractFileEngine.

This method should return an empty list if the QAbstractFileEngine refers to a file rather than a directory. It should also return an empty list if the directory is unreadable, the directory does not exist, or if there are no filter matches.

See also: setFileName()

Reimplemented in QFSFileEngine::entryList()

QFile::FileError QAbstractFileEngine::error ( ) const

Returns a value from the enum QFile::FileError which resulted from the last failed operation.

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

QString QAbstractFileEngine::errorString ( ) const

Returns the human readable message correspoding to the current error reported by calling 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 custom QAbstractFileEngine class to provide support for extensions. The value for option is the input to the extension and this method needs to store the output result in output.

The behavior of this method is determined by extension. You can call supportsExtension() to check if an extension is supported by the current 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 returns the set of flags which are true for the current file, if they match the flags in the given type.

See also: setFileName()

Reimplemented in QFSFileEngine::fileFlags()

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

virtual

Returns the file name for the current QAbstractFileEngine in the format specified by value of the file enum.

See also: setFileName(), FileName

Reimplemented in QFSFileEngine::fileName()

QDateTime QAbstractFileEngine::fileTime ( QFileDevice::FileTimeType type ) const

virtual

If type is CreationTime, returns when the file was created. If type is ModificationTime, returns when the file was most recently modified. If type is AccessTime, returns when the file was most recently accessed.

If the time can not be determined this method returns an invalid QDateTime().

See also: setFileTime(), QDateTime::isValid(), QFileDevice::FileTimeType

Reimplemented in QFSFileEngine::fileTime()

bool QAbstractFileEngine::flush ( )

virtual

Flushes the current open file and returns 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 the current QAbstractFileEngine. This handle must be used carefully since the type and value 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 for the current QAbstractFileEngine 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 random 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 specified by fileName(), to the given newName. Returns true if successful, otherwise returns false.

The definition of a link depends on the underlying file system. On Unix it is a symbolic link. On Windows a link is a shortcut. To create a valid link on Windows the given newName must have a ".lnk" file extension.

Reimplemented in QFSFileEngine::link()

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

Makes an operating system call which mirrors the contents of the current file in memory.

This method maps size bytes of the current file into memory starting at offset. Returns a pointer to the beginning of the mapped memory when successful, otherwise returns a nullptr.

Calls extension() with the enum value MapExtensionOption. If the QAbstractFileEngine does not support this extension a nullptr is returned. The value for flags is not used.

See also: supportsExtension(), unmap()

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

virtual

Creates a new directory with the specified dirName. If the operation succeeds return true, otherwise return false.

If createParentDirectories is true, then any parent directories in dirName which do not exist are also created. If createParentDirectories is false then any parent directories in dirName must already exist for this method to succeed.

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

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 returns the name of the user who owns the file. If owner is OwnerGroup returns the name of the group who owns the file. If the owner can not be determined returns an empty QString().

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

Reimplemented in QFSFileEngine::owner()

uint QAbstractFileEngine::ownerId ( FileOwner owner ) const

virtual

If owner is OwnerUser returns the ID of the user who owns the file. If owner is OwnerGroup returns the ID of the group which owns the file. If the owner can not be determined -2 is returned.

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

Reimplemented in QFSFileEngine::ownerId()

qint64 QAbstractFileEngine::pos ( ) const

virtual

Returns the current file position. This is the position where data will be read/write.

Reimplemented in QFSFileEngine::pos()

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

virtual

Reads 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 which is terminated by a '\n' character into data. At most maxlen characters will be read. The end of line character is included.

Reimplemented in QFSFileEngine::readLine()

bool QAbstractFileEngine::remove ( )

virtual

Requests the file for the current QAbstractFileEngine should be deleted from the file system. If the operation succeeds return true, otherwise return false.

See also: rmdir(), setFileName()

Reimplemented in QFSFileEngine::remove()

bool QAbstractFileEngine::rename ( const QString & newName )

virtual

Requests the file for the current QAbstractFileEngine should be renamed to newName. 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 the file for the current QAbstractFileEngine should be renamed to newName. 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 the directory dirName is deleted from the file system. When recurseParentDirectories is true, any empty parent directories must also be deleted. If recurseParentDirectories is false, only the dirName directory should be deleted. In most file systems a directory can not be deleted using this method if it is not empty. If the operation succeeds return true, otherwise return false.

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

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.

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

void QAbstractFileEngine::setFileName ( const QString & file )

virtual

Sets the filename for the current QAbstractFileEngine to file.

See also: fileName(), rename()

Reimplemented in QFSFileEngine::setFileName()

bool QAbstractFileEngine::setFileTime	(	const QDateTime &	newTime,
		QFileDevice::FileTimeType	type
	)

virtual

Sets the file time to newTime based on the given type. Returns true if successful, otherwise returns false.

The file must be open to use this method.

See also: fileTime(), QFileDevice::FileTimeType

Reimplemented in QFSFileEngine::setFileTime()

bool QAbstractFileEngine::setPermissions ( uint perms )

virtual

Set the file permission to perms. If the operation succeeds true is returned, otherwise false is returned.

See also: size()

Reimplemented in QFSFileEngine::setPermissions()

bool QAbstractFileEngine::setSize ( qint64 size )

virtual

Set the file to the given size. If size is larger than the current file the appended bytes are filled with zeros. If size is smaller, the file is truncated. If the operations succeeds returns true, otherwise returns false.

See also: size()

Reimplemented in QFSFileEngine::setSize()

qint64 QAbstractFileEngine::size ( ) const

virtual

Returns the size of the file for the current QAbstractFileEngine.

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 the contents of the file for the current QAbstractFileEngine to the file on disk. Returns true if successful, otherwise returns false.

Reimplemented in QFSFileEngine::syncToDisk()

bool QAbstractFileEngine::unmap ( uchar * address )

Makes an operating system call which clears a memory mapping. The method map() must have been previously called.

This method undoes the mapping at the given address. Returns true if this succeeds, otherwise returns false.

Calls 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 number of bytes from data to the file for the current QAbstractFileEngine. If the write succeeds, the number of characters written is returned, 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