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Class ajanta.security.acl.AclImpl

java.lang.Object
   |
   +----ajanta.security.acl.OwnerImpl
           |
           +----ajanta.security.acl.AclImpl

public class AclImpl

extends OwnerImpl

implements Acl, Serializable

See Also:

Acl

AclImpl(Principal, String)

Constructs AclImp object

addEntry(Principal, AclEntry)

Adds an ACL entry to this ACL.

checkPermission(Principal, Permission)

Checks whether or not the specified principal has the specified permission.

entries()

Returns an enumeration of the entries in this ACL.

getName()

Returns the name of this ACL.

getPermissions(Principal)

Returns an enumeration for the set of allowed permissions for the specified principal (representing an entity such as an individual or a group).

removeEntry(Principal, AclEntry)

Removes an ACL entry from this ACL.

setName(Principal, String)

Sets the name of this ACL.

toString()

Returns a string representation of the ACL contents.

 public AclImpl(Principal owner,
                String name)

Constructs AclImp object

 public void setName(Principal caller,
                     String name) throws NotOwnerException

Sets the name of this ACL.

Parameters:

caller - - the principal invoking this method. It must be an owner of this ACL.

name - - the name to be given to this ACL.

 public String getName()

Returns the name of this ACL.

Returns:

the name of this ACL.

 public boolean addEntry(Principal caller,
                         AclEntry entry) throws NotOwnerException

Adds an ACL entry to this ACL. An entry associates a principal (e.g., an individual or a group) with a set of permissions. Each principal can have at most one positive ACL entry (specifying permissions to be granted to the principal) and one negative ACL entry (specifying permissions to be denied). If there is already an ACL entry of the same type (negative or positive) already in the ACL, false is returned.

Parameters:

caller - - the principal invoking this method. It must be an owner of this ACL.

entry - - the ACL entry to be added to this ACL.

Returns:

true on success, false if an entry of the same type (positive or negative) for the same principal is already present in this ACL.

Throws: NotOwnerException

if the caller principal is not an owner of this Acl.

 public boolean removeEntry(Principal caller,
                            AclEntry entry) throws NotOwnerException

Removes an ACL entry from this ACL.

Parameters:

caller - - the principal invoking this method. It must be an owner of this ACL.

entry - - the ACL entry to be removed from this ACL.

Returns:

true on success, false if the entry is not part of this ACL.

Throws: NotOwnerException

if the caller principal is not an owner of this Acl.

 public Enumeration getPermissions(Principal user)

Returns an enumeration for the set of allowed permissions for the specified principal (representing an entity such as an individual or a group). This set of allowed permissions is calculated as follows: -> If there is no entry in this Access Control List for the specified principal, an empty permission set is returned. -> Otherwise, the principal's group permission sets are determined. (A principal can belong to one or more groups, where a group is a group of principals, represented by the Group interface.) The group positive permission set is the union of all the positive permissions of each group that the principal belongs to. The group negative permission set is the union of all the negative permissions of each group that the principal belongs to. If there is a specific permission that occurs in both the positive permission set and the negative permission set, it is removed from both. The individual positive and negative permission sets are also determined. The positive permission set contains the permissions specified in the positive ACL entry (if any) for the principal. Similarly, the negative permission set contains the permissions specified in the negative ACL entry (if any) for the principal. The individual positive (or negative) permission set is considered to be null if there is not a positive (negative) ACL entry for the principal in this ACL. The set of permissions granted to the principal is then calculated using the simple rule that individual permissions always override the group permissions. That is, the principal's individual negative permission set (specific denial of permissions) overrides the group positive permission set, and the principal's individual positive permission set overrides the group negative permission set. Assume that the positive permission set of all the groups that the principal belongs to is g1 and the negative permission set of all the groups that the principal belongs to is g2. Also assume that the individual positive permission set for the principal is p1 and the individual negative permission set for the principal is p2. Then the resulting permissions that the principal is granted are (p1 + (g1 - p2)) - (p2 + (g2 - p1))

Parameters:

user - - the principal whose permission set is to be returned.

Returns:

the permission set specifying the permissions the principal is allowed.

 public Enumeration entries()

Returns an enumeration of the entries in this ACL. Each element in the enumeration is of type AclEntry.

Returns:

an enumeration of the entries in this ACL.

 public boolean checkPermission(Principal principal,
                                Permission permission)

Checks whether or not the specified principal has the specified permission. it does, true is returned, otherwise false is returned. More specifically, thiis method checks whether the passed permission is a member of the allowed permission set of the specified principal. The allowed permission set is determined by the same algorithm as is used by the getPermissions method.

Parameters:

permission - - the permission to be checked for.

Returns:

true if the principal has the specified permission, false otherwise.

 public String toString()

Returns a string representation of the ACL contents.

Returns:

a string representation of the ACL contents.

Overrides:

toString in class Object

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