org.apache.tools.ant.util

Class SymbolicLinkUtils

java.lang.Object

org.apache.tools.ant.util.SymbolicLinkUtils

public class SymbolicLinkUtils
extends Object

Contains methods related to symbolic links - or what Ant thinks is a symbolic link based on the absent support for them in Java.

Since:

Ant 1.8.0

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SymbolicLinkUtils() Empty constructor.

Method Summary

Modifier and Type	Method and Description
void	deleteSymbolicLink(File link, Task task) Delete a symlink (without deleting the associated resource).
static SymbolicLinkUtils	getSymbolicLinkUtils() Method to retrieve The SymbolicLinkUtils, which is shared by all users of this method.
boolean	isDanglingSymbolicLink(File file) Checks whether a given file is a broken symbolic link.
boolean	isDanglingSymbolicLink(File parent, String name) Checks whether a given file is a broken symbolic link.
boolean	isDanglingSymbolicLink(String name) Checks whether a given file is a broken symbolic link.
boolean	isSymbolicLink(File file) Checks whether a given file is a symbolic link.
boolean	isSymbolicLink(File parent, String name) Checks whether a given file is a symbolic link.
boolean	isSymbolicLink(String name) Checks whether a given file is a symbolic link.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SymbolicLinkUtils

protected SymbolicLinkUtils()

Empty constructor.

Method Detail

deleteSymbolicLink

public void deleteSymbolicLink(File link,
                               Task task)
                        throws IOException

Delete a symlink (without deleting the associated resource).

This is a utility method that removes a unix symlink without removing the resource that the symlink points to. If it is accidentally invoked on a real file, the real file will not be harmed, but silently ignored.

Normally this method works by getting the canonical path of the link, using the canonical path to rename the resource (breaking the link) and then deleting the link. The resource is then returned to its original name inside a finally block to ensure that the resource is unharmed even in the event of an exception.

There may be cases where the algorithm described above doesn't work, in that case the method tries to use the native "rm" command on the symlink instead.

Parameters:

link - A File object of the symlink to delete.

task - An Ant Task required if "rm" needs to be invoked.

Throws:

IOException - If calls to File.rename, File.delete or File.getCanonicalPath fail.

BuildException - if the execution of "rm" failed.

getSymbolicLinkUtils

public static SymbolicLinkUtils getSymbolicLinkUtils()

Method to retrieve The SymbolicLinkUtils, which is shared by all users of this method.

Returns:

an instance of SymbolicLinkUtils.

isDanglingSymbolicLink

public boolean isDanglingSymbolicLink(File file)
                               throws IOException

Checks whether a given file is a broken symbolic link.

It doesn't really test for symbolic links but whether Java reports that the File doesn't exist but its parent's child list contains it--this may lead to false positives on some platforms.

Note that #isSymbolicLink returns false if this method returns true since Java won't produce a canonical name different from the abolute one if the link is broken.

Parameters:

file - the file to test.

Returns:

true if the file is a broken symbolic link.

Throws:

IOException - on error.

isDanglingSymbolicLink

public boolean isDanglingSymbolicLink(File parent,
                                      String name)
                               throws IOException

Checks whether a given file is a broken symbolic link.

It doesn't really test for symbolic links but whether Java reports that the File doesn't exist but its parent's child list contains it--this may lead to false positives on some platforms.

Note that #isSymbolicLink returns false if this method returns true since Java won't produce a canonical name different from the abolute one if the link is broken.

Parameters:

parent - the parent directory of the file to test

name - the name of the file to test.

Returns:

true if the file is a broken symbolic link.

Throws:

IOException - on error.

isDanglingSymbolicLink

public boolean isDanglingSymbolicLink(String name)
                               throws IOException

Checks whether a given file is a broken symbolic link.

It doesn't really test for symbolic links but whether Java reports that the File doesn't exist but its parent's child list contains it--this may lead to false positives on some platforms.

Note that #isSymbolicLink returns false if this method returns true since Java won't produce a canonical name different from the abolute one if the link is broken.

Parameters:

name - the name of the file to test.

Returns:

true if the file is a broken symbolic link.

Throws:

IOException - on error.

isSymbolicLink

public boolean isSymbolicLink(File file)
                       throws IOException

Checks whether a given file is a symbolic link.

It doesn't really test for symbolic links but whether the canonical and absolute paths of the file are identical--this may lead to false positives on some platforms.

Parameters:

file - the file to test. Must not be null.

Returns:

true if the file is a symbolic link.

Throws:

IOException - on error.

isSymbolicLink

public boolean isSymbolicLink(File parent,
                              String name)
                       throws IOException

Checks whether a given file is a symbolic link.

It doesn't really test for symbolic links but whether the canonical and absolute paths of the file are identical--this may lead to false positives on some platforms.

Parameters:

parent - the parent directory of the file to test

name - the name of the file to test.

Returns:

true if the file is a symbolic link.

Throws:

IOException - on error.

isSymbolicLink

public boolean isSymbolicLink(String name)
                       throws IOException

Checks whether a given file is a symbolic link.

It doesn't really test for symbolic links but whether the canonical and absolute paths of the file are identical--this may lead to false positives on some platforms.

Parameters:

name - the name of the file to test.

Returns:

true if the file is a symbolic link.

Throws:

IOException - on error.