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added in API level 26

SecureDirectoryStream

public interface SecureDirectoryStream
implements DirectoryStream<T>

java.nio.file.SecureDirectoryStream<T>


A DirectoryStream that defines operations on files that are located relative to an open directory. A SecureDirectoryStream is intended for use by sophisticated or security sensitive applications requiring to traverse file trees or otherwise operate on directories in a race-free manner. Race conditions can arise when a sequence of file operations cannot be carried out in isolation. Each of the file operations defined by this interface specify a relative path. All access to the file is relative to the open directory irrespective of if the directory is moved or replaced by an attacker while the directory is open. A SecureDirectoryStream may also be used as a virtual working directory.

A SecureDirectoryStream requires corresponding support from the underlying operating system. Where an implementation supports this features then the DirectoryStream returned by the newDirectoryStream method will be a SecureDirectoryStream and must be cast to that type in order to invoke the methods defined by this interface.

In the case of the default provider, and a security manager is set, then the permission checks are performed using the path obtained by resolving the given relative path against the original path of the directory (irrespective of if the directory is moved since it was opened).

Summary

Public methods

abstract void deleteDirectory(T path)

Deletes a directory.

abstract void deleteFile(T path)

Deletes a file.

abstract <V extends FileAttributeView> V getFileAttributeView(Class<V> type)

Returns a new file attribute view to access the file attributes of this directory.

abstract <V extends FileAttributeView> V getFileAttributeView(T path, Class<V> type, LinkOption... options)

Returns a new file attribute view to access the file attributes of a file in this directory.

abstract void move(T srcpath, SecureDirectoryStream<T> targetdir, T targetpath)

Move a file from this directory to another directory.

abstract SeekableByteChannel newByteChannel(T path, Set<? extends OpenOption> options, FileAttribute...<?> attrs)

Opens or creates a file in this directory, returning a seekable byte channel to access the file.

abstract SecureDirectoryStream<T> newDirectoryStream(T path, LinkOption... options)

Opens the directory identified by the given path, returning a SecureDirectoryStream to iterate over the entries in the directory.

Inherited methods

Public methods

deleteDirectory

added in API level 26
public abstract void deleteDirectory (T path)

Deletes a directory.

Unlike the delete() method, this method does not first examine the file to determine if the file is a directory. Whether non-directories are deleted by this method is system dependent and therefore not specified. When the parameter is a relative path then the directory to delete is relative to this open directory.

Parameters
path T: the path of the directory to delete

Throws
ClosedDirectoryStreamException if the directory stream is closed
NoSuchFileException if the directory does not exist (optional specific exception)
DirectoryNotEmptyException if the directory could not otherwise be deleted because it is not empty (optional specific exception)
IOException if an I/O error occurs
SecurityException In the case of the default provider, and a security manager is installed, the checkDelete method is invoked to check delete access to the directory

deleteFile

added in API level 26
public abstract void deleteFile (T path)

Deletes a file.

Unlike the delete() method, this method does not first examine the file to determine if the file is a directory. Whether a directory is deleted by this method is system dependent and therefore not specified. If the file is a symbolic link, then the link itself, not the final target of the link, is deleted. When the parameter is a relative path then the file to delete is relative to this open directory.

Parameters
path T: the path of the file to delete

Throws
ClosedDirectoryStreamException if the directory stream is closed
NoSuchFileException if the file does not exist (optional specific exception)
IOException if an I/O error occurs
SecurityException In the case of the default provider, and a security manager is installed, the checkDelete method is invoked to check delete access to the file

getFileAttributeView

added in API level 26
public abstract V getFileAttributeView (Class<V> type)

Returns a new file attribute view to access the file attributes of this directory.

The resulting file attribute view can be used to read or update the attributes of this (open) directory. The type parameter specifies the type of the attribute view and the method returns an instance of that type if supported. Invoking this method to obtain a BasicFileAttributeView always returns an instance of that class that is bound to this open directory.

The state of resulting file attribute view is intimately connected to this directory stream. Once the directory stream is closed, then all methods to read or update attributes will throw ClosedDirectoryStreamException.

Parameters
type Class: the Class object corresponding to the file attribute view

Returns
V a new file attribute view of the specified type bound to this directory stream, or null if the attribute view type is not available

getFileAttributeView

added in API level 26
public abstract V getFileAttributeView (T path, 
                Class<V> type, 
                LinkOption... options)

Returns a new file attribute view to access the file attributes of a file in this directory.

The resulting file attribute view can be used to read or update the attributes of file in this directory. The type parameter specifies the type of the attribute view and the method returns an instance of that type if supported. Invoking this method to obtain a BasicFileAttributeView always returns an instance of that class that is bound to the file in the directory.

The state of resulting file attribute view is intimately connected to this directory stream. Once the directory stream closed, then all methods to read or update attributes will throw ClosedDirectoryStreamException. The file is not required to exist at the time that the file attribute view is created but methods to read or update attributes of the file will fail when invoked and the file does not exist.

Parameters
path T: the path of the file

type Class: the Class object corresponding to the file attribute view

options LinkOption: options indicating how symbolic links are handled

Returns
V a new file attribute view of the specified type bound to a this directory stream, or null if the attribute view type is not available

move

added in API level 26
public abstract void move (T srcpath, 
                SecureDirectoryStream<T> targetdir, 
                T targetpath)

Move a file from this directory to another directory.

This method works in a similar manner to move method when the ATOMIC_MOVE option is specified. That is, this method moves a file as an atomic file system operation. If the srcpath parameter is an absolute path then it locates the source file. If the parameter is a relative path then it is located relative to this open directory. If the targetpath parameter is absolute then it locates the target file (the targetdir parameter is ignored). If the parameter is a relative path it is located relative to the open directory identified by the targetdir parameter. In all cases, if the target file exists then it is implementation specific if it is replaced or this method fails.

Parameters
srcpath T: the name of the file to move

targetdir SecureDirectoryStream: the destination directory

targetpath T: the name to give the file in the destination directory

Throws
ClosedDirectoryStreamException if this or the target directory stream is closed
FileAlreadyExistsException if the file already exists in the target directory and cannot be replaced (optional specific exception)
AtomicMoveNotSupportedException if the file cannot be moved as an atomic file system operation
IOException if an I/O error occurs
SecurityException In the case of the default provider, and a security manager is installed, the checkWrite method is invoked to check write access to both the source and target file.

newByteChannel

added in API level 26
public abstract SeekableByteChannel newByteChannel (T path, 
                Set<? extends OpenOption> options, 
                FileAttribute...<?> attrs)

Opens or creates a file in this directory, returning a seekable byte channel to access the file.

This method works in exactly the manner specified by the Files.newByteChannel method for the case that the path parameter is an absolute path. When the parameter is a relative path then the file to open or create is relative to this open directory. In addition to the options defined by the Files.newByteChannel method, the NOFOLLOW_LINKS option may be used to ensure that this method fails if the file is a symbolic link.

The channel, once created, is not dependent upon the directory stream used to create it. Closing this directory stream has no effect upon the channel.

Parameters
path T: the path of the file to open open or create

options Set: options specifying how the file is opened

attrs FileAttribute: an optional list of attributes to set atomically when creating the file

Returns
SeekableByteChannel the seekable byte channel

Throws
ClosedDirectoryStreamException if the directory stream is closed
IllegalArgumentException if the set contains an invalid combination of options
UnsupportedOperationException if an unsupported open option is specified or the array contains attributes that cannot be set atomically when creating the file
FileAlreadyExistsException if a file of that name already exists and the CREATE_NEW option is specified (optional specific exception)
IOException if an I/O error occurs
SecurityException In the case of the default provider, and a security manager is installed, the checkRead method is invoked to check read access to the path if the file is opened for reading. The checkWrite method is invoked to check write access to the path if the file is opened for writing.

newDirectoryStream

added in API level 26
public abstract SecureDirectoryStream<T> newDirectoryStream (T path, 
                LinkOption... options)

Opens the directory identified by the given path, returning a SecureDirectoryStream to iterate over the entries in the directory.

This method works in exactly the manner specified by the newDirectoryStream method for the case that the path parameter is an absolute path. When the parameter is a relative path then the directory to open is relative to this open directory. The NOFOLLOW_LINKS option may be used to ensure that this method fails if the file is a symbolic link.

The new directory stream, once created, is not dependent upon the directory stream used to create it. Closing this directory stream has no effect upon newly created directory stream.

Parameters
path T: the path to the directory to open

options LinkOption: options indicating how symbolic links are handled

Returns
SecureDirectoryStream<T> a new and open SecureDirectoryStream object

Throws
ClosedDirectoryStreamException if the directory stream is closed
NotDirectoryException if the file could not otherwise be opened because it is not a directory (optional specific exception)
IOException if an I/O error occurs
SecurityException In the case of the default provider, and a security manager is installed, the checkRead method is invoked to check read access to the directory.