FilePermission JDK 1.6)

Description

publicfinal class FilePermission

This class represents access to a file or directory.

This class represents access to a file or directory. A FilePermission consists of a pathname and a set of actions valid for that pathname.

Pathname is the pathname of the file or directory granted the specified actions. A pathname that ends in "/*" (where "/" is the file separator character, File.separatorChar) indicates all the files and directories contained in that directory. A pathname that ends with "/-" indicates (recursively) all files and subdirectories contained in that directory. A pathname consisting of the special token "<<ALL FILES>>" matches any file.

Note: A pathname consisting of a single "*" indicates all the files in the current directory, while a pathname consisting of a single "-" indicates all the files in the current directory and (recursively) all files and subdirectories contained in the current directory.

The actions to be granted are passed to the constructor in a string containing a list of one or more comma-separated keywords. The possible keywords are "read", "write", "execute", and "delete". Their meaning is defined as follows:

read: read permission
write: write permission
execute: execute permission. Allows Runtime.exec to be called. Corresponds to SecurityManager.checkExec.
delete: delete permission. Allows File.delete to be called. Corresponds to SecurityManager.checkDelete.

The actions string is converted to lowercase before processing.

Be careful when granting FilePermissions. Think about the implications of granting read and especially write access to various files and directories. The "<<ALL FILES>>" permission with write action is especially dangerous. This grants permission to write to the entire file system. One thing this effectively allows is replacement of the system binary, including the JVM runtime environment.

Please note: Code can always read a file from the same directory it's in (or a subdirectory of that directory); it does not need explicit permission to do so.

See also: Permission Permissions PermissionCollection

Constructors

pack-private FilePermission (String path, int mask)

Creates a new FilePermission object using an action mask.

Creates a new FilePermission object using an action mask.
More efficient than the FilePermission(String, String) constructor.
Can be used from within
code that needs to create a FilePermission object to pass into the
implies method.
Parameters:
- path - the pathname of the file/directory.
- mask - the action mask to use.

public FilePermission (String path, String actions)

Creates a new FilePermission object with the specified actions.

Methods

Hide/Show inherited methods

public void checkGuard (Object object) throws SecurityException [Inherited From Permission]

Implements the guard interface for a permission.

Implements the guard interface for a permission. The
SecurityManager.checkPermission method is called,
passing this permission object as the permission to check.
Returns silently if access is granted. Otherwise, throws
a SecurityException.
Parameters:
- object - the object being guarded (currently ignored).
Throws:
- SecurityException - if a security manager exists and its checkPermission method doesn't allow access.
See Also: Guard, GuardedObject, SecurityManager.checkPermission(java.security.Permission),

public boolean equals (Object obj) [Specified in Permission]

Checks two FilePermission objects for equality.

public String getActions () [Specified in Permission]

Returns the "canonical string representation" of the actions.

Returns the "canonical string representation" of the actions.
That is, this method always returns present actions in the following order:
read, write, execute, delete. For example, if this FilePermission object
allows both write and read actions, a call to getActions
will return the string "read,write".
Returns: the canonical string representation of the actions.

pack-private int getMask ()

Return the current action mask.

publicfinal String getName () [Inherited From Permission]

Returns the name of this Permission.

Returns the name of this Permission.
For example, in the case of a java.io.FilePermission,
the name will be a pathname.
Returns: the name of this Permission.

public int hashCode () [Specified in Permission]

Returns the hash code value for this object.

public boolean implies (Permission p) [Specified in Permission]

Checks if this FilePermission object "implies" the specified permission.

More specifically, this method returns true if:

p is an instanceof FilePermission,
p's actions are a proper subset of this object's actions, and
p's pathname is implied by this object's pathname. For example, "/tmp/*" implies "/tmp/foo", since "/tmp/*" encompasses all files in the "/tmp" directory, including the one named "foo".

Returns: true if the specified permission is not null and is implied by this object, false otherwise.
Parameters:
- p - the permission to check against.

pack-private boolean impliesIgnoreMask (FilePermission that)

Checks if the Permission's actions are a proper subset of the this object's actions.

public PermissionCollection newPermissionCollection () [Overrides Permission]

Returns a new PermissionCollection object for storing FilePermission objects.

FilePermission objects must be stored in a manner that allows them to be inserted into the collection in any order, but that also enables the PermissionCollection implies method to be implemented in an efficient (and consistent) manner.

For example, if you have two FilePermissions:

"/tmp/-", "read"
"/tmp/scratch/foo", "write"

and you are calling the implies method with the FilePermission:

   "/tmp/scratch/foo", "read,write",

then the implies function must take into account both the "/tmp/-" and "/tmp/scratch/foo" permissions, so the effective permission is "read,write", and implies returns true. The "implies" semantics for FilePermissions are handled properly by the PermissionCollection object returned by this newPermissionCollection method.
Returns: a new PermissionCollection object suitable for storing FilePermissions.

public String toString () [Inherited From Permission]

Returns a string describing this Permission.