Serializable
, Guard
public final class FilePermission extends Permission implements Serializable
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. Such a pathname is called a wildcard pathname. Otherwise, it's a simple pathname.
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", "delete", and "readlink". Their meaning is defined as follows:
Runtime.exec
to be called. Corresponds to SecurityManager.checkExec
. File.delete
to be called. Corresponds to SecurityManager.checkDelete
. readSymbolicLink
method. 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.
Constructor | Description |
---|---|
FilePermission |
Creates a new FilePermission object with the specified actions. |
Modifier and Type | Method | Description |
---|---|---|
boolean |
equals |
Checks two FilePermission objects for equality. |
String |
getActions() |
Returns the "canonical string representation" of the actions. |
int |
hashCode() |
Returns the hash code value for this object. |
boolean |
implies |
Checks if this FilePermission object "implies" the specified permission. |
PermissionCollection |
newPermissionCollection() |
Returns a new PermissionCollection object for storing FilePermission objects. |
checkGuard, getName, toString
public FilePermission(String path, String 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. The special pathname "<<ALL FILES>>" matches any file.
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.
A pathname containing an empty string represents an empty path.
jdk.io.permissionsUseCanonicalPath
system property dictates how the path
argument is processed and stored. If the value of the system property is set to true
, path
is canonicalized and stored as a String object named cpath
. This means a relative path is converted to an absolute path, a Windows DOS-style 8.3 path is expanded to a long path, and a symbolic link is resolved to its target, etc.
If the value of the system property is set to false
, path
is converted to a Path
object named npath
after normalization
. No canonicalization is performed which means the underlying file system is not accessed. If an InvalidPathException
is thrown during the conversion, this FilePermission
will be labeled as invalid.
In either case, the "*" or "-" character at the end of a wildcard path
is removed before canonicalization or normalization. It is stored in a separate wildcard flag field.
The default value of the jdk.io.permissionsUseCanonicalPath
system property is false
in this implementation.
The value can also be set with a security property using the same name, but setting a system property will override the security property value.
path
- the pathname of the file/directory.actions
- the action string.IllegalArgumentException
- if actions is null
, empty, malformed or contains an action other than the specified possible actionspublic boolean implies(Permission p)
More specifically, this method returns true if:
Precisely, a simple pathname implies another simple pathname if and only if they are equal. A simple pathname never implies a wildcard pathname. A wildcard pathname implies another wildcard pathname if and only if all simple pathnames implied by the latter are implied by the former. A wildcard pathname implies a simple pathname if and only if
"<<ALL FILES>>" implies every other pathname. No pathname, except for "<<ALL FILES>>" itself, implies "<<ALL FILES>>".
implies
in class Permission
jdk.io.permissionsUseCanonicalPath
is true
, a simple cpath
is inside a wildcard cpath
if and only if after removing the base name (the last name in the pathname's name sequence) from the former the remaining part is equal to the latter, a simple cpath
is recursively inside a wildcard cpath
if and only if the former starts with the latter. If jdk.io.permissionsUseCanonicalPath
is false
, a simple npath
is inside a wildcard npath
if and only if simple_npath.relativize(wildcard_npath)
is exactly "..", a simple npath
is recursively inside a wildcard npath
if and only if simple_npath.relativize(wildcard_npath)
is a series of one or more "..". This means "/-" implies "/foo" but not "foo".
An invalid FilePermission
does not imply any object except for itself. An invalid FilePermission
is not implied by any object except for itself or a FilePermission
on "<<ALL FILES>>" whose actions is a superset of this invalid FilePermission
. Even if two FilePermission
are created with the same invalid path, one does not imply the other.
p
- the permission to check against.true
if the specified permission is not null
and is implied by this object, false
otherwise.public boolean equals(Object obj)
equals
in class Permission
cpath
(if jdk.io.permissionsUseCanonicalPath
is true
) or npath
(if jdk.io.permissionsUseCanonicalPath
is false
) are equal. Or they are both "<<ALL FILES>>". When jdk.io.permissionsUseCanonicalPath
is false
, an invalid FilePermission
does not equal to any object except for itself, even if they are created using the same invalid path.
obj
- the object we are testing for equality with this object.true
if obj is a FilePermission, and has the same pathname and actions as this FilePermission object, false
otherwise.public int hashCode()
hashCode
in class Permission
public String getActions()
getActions
will return the string "read,write".getActions
in class Permission
public PermissionCollection newPermissionCollection()
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.newPermissionCollection
in class Permission
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/FilePermission.html