CopperSpice API  1.7.2
QAbstractFileEngine Class Reference

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

Inheritance diagram for QAbstractFileEngine:
QFSFileEngine

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...
 

Public Typedefs

using FileFlags = QFlags< FileFlag >
 
typedef QAbstractFileEngineIterator Iterator
 

Public Types

enum  Extension
 
enum  FileFlag
 
enum  FileName
 
enum  FileOwner
 
enum  FileTime
 

Public Methods

virtual ~QAbstractFileEngine ()
 
bool atEnd () const
 
virtual IteratorbeginEntryList (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)
 
ucharmap (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 the referent is a file, the setFileName(), rename(), and remove() functions are applicable. If the referent is a directory the mkdir(), rmdir(), and entryList() functions are applicable. In all cases the caseSensitive(), isRelativePath(), fileFlags(), ownerId(), owner(), and fileTime() functions 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

Member Enumeration Documentation

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()).

ConstantValueDescription
QAbstractFileEngine::AtEndExtension0 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::FastReadLineExtension1 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::MapExtension2 Whether the file engine provides the ability to map a file to memory.
QAbstractFileEngine::UnMapExtension3 Whether the file engine provides the ability to unmap memory that was previously mapped.

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

ConstantValueDescription
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 functions.
QAbstractFileEngine::Refresh 0x1000000 Passing this flag will force the file engine to refresh all flags.
See also
fileFlags(), setFileName()

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

ConstantValueDescription
QAbstractFileEngine::DefaultName0Same filename that was passed to the QAbstractFileEngine.
QAbstractFileEngine::BaseName1Name of the file excluding the path.
QAbstractFileEngine::PathName2Path to the file excluding the base name.
QAbstractFileEngine::AbsoluteName3Absolute path to the file (including the base name).
QAbstractFileEngine::AbsolutePathName4Absolute path to the file (excluding the base name).
QAbstractFileEngine::LinkName5 Full file name of the file this file is a link to, will be empty if this file is not a link
QAbstractFileEngine::CanonicalName6 Often very similar to LinkName. Will return the true path to the file.
QAbstractFileEngine::CanonicalPathName7Same as CanonicalName, excluding the base name.
QAbstractFileEngine::BundleName8Returns the name of the bundle implies BundleType is set.
See also
fileName(), setFileName()
ConstantValueDescription
QAbstractFileEngine::OwnerUser0User who owns the file.
QAbstractFileEngine::OwnerGroup1Group who owns the file.
See also
owner(), ownerId(), setFileName()

These are used by the fileTime() function.

ConstantValueDescription
QAbstractFileEngine::CreationTime0 When the file was created.
QAbstractFileEngine::ModificationTime1 When the file was most recently modified.
QAbstractFileEngine::AccessTime2 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()
Iterator * QAbstractFileEngine::beginEntryList ( QDir::Filters  filters,
const QStringList filterNames 
)
virtual

Returns an instance of a QAbstractFileEngineIterator using filters for entry filtering and filterNames for name filtering. This method is called by QDirIterator to initiate directory iteration.

QDirIterator takes ownership of the returned instance, and deletes it when it is done.

See also
QDirIterator

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::caseSensitive ( ) const
virtual

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

This virtual method must be reimplemented by all subclasses.

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::close ( )
virtual

Closes the file, returning true if successful, otherwise returns false.

The default implementation always returns false.

Reimplemented in QFSFileEngine.

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.

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

Creates and returns a QAbstractFileEngine suitable for processing fileName. You should not need to call this function; use QFile, QFileInfo or QDir directly instead.

If you reimplement this function, 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.

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.

This virtual function must be reimplemented by all subclasses.

See also
setFileName()

Reimplemented in QFSFileEngine.

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

The behavior of this function is determined by extension; see the Extension documentation for details.

You can call supportsExtension() to check if an extension is supported by the file engine.

By default, no extensions are supported, and this function returns false.

See also
supportsExtension(), Extension
FileFlags QAbstractFileEngine::fileFlags ( FileFlags  type = FileInfoAll) const
virtual

This function should return the set of OR'd flags that are true for the file engine's file, and that are in the type's OR'd members.

In your reimplementation you can use the type argument as an optimization hint and only return the OR'd set of members that are true and that match those in type; in other words you can ignore any members not mentioned in type, thus avoiding some potentially expensive lookups or system calls.

This virtual function must be reimplemented by all subclasses.

See also
setFileName()

Reimplemented in QFSFileEngine.

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.

This virtual function must be reimplemented by all subclasses.

See also
setFileName(), FileName

Reimplemented in QFSFileEngine.

QDateTime QAbstractFileEngine::fileTime ( FileTime  time) const
virtual

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

This virtual function must be reimplemented by all subclasses.

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

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::flush ( )
virtual

Flushes the open file, returning true if successful, otherwise returns false.

The default implementation always returns false.

Reimplemented in QFSFileEngine.

int QAbstractFileEngine::handle ( ) const
virtual

Returns the native file handle for this file engine. This handle must be used with care; its value and type are platform specific, and using it will most likely lead to non-portable code.

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::isRelativePath ( ) const
virtual

Return true if the file referred to by this file engine has a relative path, otherwise return false. This virtual function must be reimplemented by all subclasses.

See also
setFileName()

Reimplemented in QFSFileEngine.

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.

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.

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 if successful, otherwise returns false if, for example, an error occurs.

This function bases its behavior on calling extension() with MapExtensionOption. If the engine does not support this extension, 0 is returned.

flags is currently not used, but could be used in the future.

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 function to succeed. If the operation succeeds return true, otherwise return false.

This virtual function must be reimplemented by all subclasses.

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

Reimplemented in QFSFileEngine.

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.

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().

This virtual function must be reimplemented by all subclasses.

See also
ownerId(), setFileName(), FileOwner

Reimplemented in QFSFileEngine.

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.

This virtual function must be reimplemented by all subclasses.

See also
owner(), setFileName(), FileOwner

Reimplemented in QFSFileEngine.

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.

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.

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

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

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::remove ( )
virtual

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

This virtual function must be reimplemented by all subclasses.

See also
setFileName(), rmdir()

Reimplemented in QFSFileEngine.

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.

This virtual function must be reimplemented by all subclasses.

See also
setFileName()

Reimplemented in QFSFileEngine.

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.

This virtual function must be reimplemented by all subclasses.

See also
setFileName()

Reimplemented in QFSFileEngine.

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 function if it is non-empty. If the operation succeeds return true, otherwise return false.

This virtual function must be reimplemented by all subclasses.

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

Reimplemented in QFSFileEngine.

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.

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

Sets the error type to error, and the error string to errorString. Call this function 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 virtual functions will operate on.

This virtual function must be reimplemented by all subclasses.

See also
fileName(), rename()

Reimplemented in QFSFileEngine.

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;

This virtual function must be reimplemented by all subclasses.

See also
size()

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::setSize ( qint64  size)
virtual

Requests that the file be set to size size. If size is larger than the current file then it is filled with 0's, if smaller it is simply truncated. If the operations succeeds return true, otherwise return false;

This virtual function must be reimplemented by all subclasses.

See also
size()

Reimplemented in QFSFileEngine.

qint64 QAbstractFileEngine::size ( ) const
virtual

Returns the size of the file.

See also
setSize()

Reimplemented in QFSFileEngine.

bool QAbstractFileEngine::supportsExtension ( Extension  extension) const
virtual

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

See also
extension()

Reimplemented in QFSFileEngine.

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.

bool QAbstractFileEngine::unmap ( uchar address)

Unmaps the memory address. Returns true if the unmap succeeds, otherwise returns false.

This function 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.