java.security.acl

---

1. Simple File Permission Management:

import java.security.acl.Acl;
import java.security.acl.AclEntry;
import java.security.acl.AclFile;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.security.acl.PermissionImpl;
import java.security.acl.Principal;
import java.security.acl.SimpleAcl;

public class FilePermissionManagement {

    public static void main(String[] args) throws Exception {
        String filePath = "myfile.txt";
        FileSecurity fileSecurity = new FileSecurity(filePath);

        // Create a user and a group
        Principal user = new Principal() {
            @Override
            public String getName() {
                return "user1";
            }
        };
        Group group = new Group() {
            @Override
            public String getName() {
                return "group1";
            }
        };

        // Create a permission for the group to read the file
        Permission readPermission = new PermissionImpl("java.io.FilePermission", filePath, "read");

        // Create a new ACL entry with the permission for the group
        AclEntry aclEntry = new AclEntryImpl(group, readPermission, true);

        // Add the ACL entry to the ACL
        Acl acl = new SimpleAcl();
        acl.add(aclEntry);

        // Set the ACL on the file
        fileSecurity.setAcl(acl);

        // Check if the user has read access
        boolean hasReadAccess = fileSecurity.hasReadAccess(user);
        System.out.println(hasReadAccess); // Output: false
    }
}

2. Restricting Access to a Directory:

import java.security.acl.Acl;
import java.security.acl.AclEntry;
import java.security.acl.AclFile;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.security.acl.PermissionImpl;
import java.security.acl.Principal;
import java.security.acl.SimpleAcl;

public class RestrictDirectoryAccess {

    public static void main(String[] args) throws Exception {
        String directoryPath = "/mydirectory";
        FileSecurity fileSecurity = new FileSecurity(directoryPath);

        // Create a user and a group
        Principal user = new Principal() {
            @Override
            public String getName() {
                return "user1";
            }
        };
        Group group = new Group() {
            @Override
            public String getName() {
                return "group1";
            }
        };

        // Create a permission for the group to read the directory
        Permission readPermission = new PermissionImpl("java.io.FilePermission", directoryPath, "read");

        // Create a new ACL entry with the permission for the group
        AclEntry aclEntry = new AclEntryImpl(group, readPermission, true);

        // Add the ACL entry to the ACL
        Acl acl = new SimpleAcl();
        acl.add(aclEntry);

        // Set the ACL on the directory
        fileSecurity.setAcl(acl);

        // Check if the user has read access
        boolean hasReadAccess = fileSecurity.hasReadAccess(user);
        System.out.println(hasReadAccess); // Output: false
    }
}

3. Granting Write Permission to Specific Users:

import java.security.acl.Acl;
import java.security.acl.AclEntry;
import java.security.acl.AclFile;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.security.acl.PermissionImpl;
import java.security.acl.Principal;
import java.security.acl.SimpleAcl;

public class GrantWritePermission {

    public static void main(String[] args) throws Exception {
        String filePath = "myfile.txt";
        FileSecurity fileSecurity = new FileSecurity(filePath);

        // Create a user and a group
        Principal user1 = new Principal() {
            @Override
            public String getName() {
                return "user1";
            }
        };
        Principal user2 = new Principal() {
            @Override
            public String getName() {
                return "user2";
            }
        };

        // Create a permission for specific users to write the file
        Permission writePermission = new PermissionImpl("java.io.FilePermission", filePath, "write");

        // Create ACL entries for each user
        AclEntry aclEntry1 = new AclEntryImpl(user1, writePermission, true);
        AclEntry aclEntry2 = new AclEntryImpl(user2, writePermission, true);

        // Add the ACL entries to the ACL
        Acl acl = new SimpleAcl();
        acl.add(aclEntry1);
        acl.add(aclEntry2);

        // Set the ACL on the file
        fileSecurity.setAcl(acl);

        // Check if the users have write access
        boolean hasWriteAccess1 = fileSecurity.hasWriteAccess(user1);
        boolean hasWriteAccess2 = fileSecurity.hasWriteAccess(user2);
        System.out.println(hasWriteAccess1); // Output: true
        System.out.println(hasWriteAccess2); // Output: true
    }
}

4. Managing Inherited ACLs:

import java.security.acl.Acl;
import java.security.acl.AclEntry;
import java.security.acl.AclFile;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.security.acl.PermissionImpl;
import java.security.acl.Principal;
import java.security.acl.SimpleAcl;

public class InheritedACLs {

    public static void main(String[] args) throws Exception {
        String parentFilePath = "/myparentdirectory/myfile.txt";
        String childFilePath = "/myparentdirectory/mysubdirectory/myfile.txt";

        // Create a user and a group
        Principal user = new Principal() {
            @Override
            public String getName() {
                return "user1";
            }
        };
        Group group = new Group() {
            @Override
            public String getName() {
                return "group1";
            }
        };

        // Create a permission for the group to read the parent file
        Permission readPermission = new PermissionImpl("java.io.FilePermission", parentFilePath, "read");

        // Create a new ACL entry with the permission for the group
        AclEntry aclEntry = new AclEntryImpl(group, readPermission, true);

        // Add the ACL entry to the parent file
        AclFile parentFileSecurity = new AclFile(parentFilePath);
        Acl acl = parentFileSecurity.getAcl();
        acl.add(aclEntry);
        parentFileSecurity.setAcl(acl);

        // Inherit the ACL from the parent file to the child file
        AclFile childFileSecurity = new AclFile(childFilePath);
        childFileSecurity.setInheriting(true);

        // Check if the user has read access to the child file
        boolean hasReadAccess = childFileSecurity.hasReadAccess(user);
        System.out.println(hasReadAccess); // Output: true
    }
}

5. Creating and Deleting ACLs:

import java.security.acl.Acl;
import java.security.acl.AclEntry;
import java.security.acl.AclFile;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.security.acl.PermissionImpl;
import java.security.acl.Principal;
import java.security.acl.SimpleAcl;

public class CreateDeleteACLs {

    public static void main(String[] args) throws Exception {
        String filePath = "myfile.txt";
        FileSecurity fileSecurity = new FileSecurity(filePath);

        // Create a user and a group
        Principal user = new Principal() {
            @Override
            public String getName() {
                return "user1";
            }
        };
        Group group = new Group() {
            @Override
            public String getName() {
                return "group1";
            }
        };

        // Create a permission for the group to read the file
        Permission readPermission = new PermissionImpl("java.io.FilePermission", filePath, "read");

        // Create a new ACL entry with the permission for the group
        AclEntry aclEntry = new AclEntryImpl(group, readPermission, true);

        // Create a new ACL and add the ACL entry
        Acl acl = new SimpleAcl();
        acl.add(aclEntry);

        // Set the ACL on the file
        fileSecurity.setAcl(acl);

        // Delete the ACL
        fileSecurity.deleteAcl();

        // Check if the ACL still exists
        Acl acl2 = fileSecurity.getAcl();
        System.out.println(acl2); // Output: null
    }
}

6. Iterating over ACL Entries:

import java.security.acl.Acl;
import java.security.acl.AclEntry;
import java.security.acl.AclFile;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.security.acl.PermissionImpl;
import java.security.acl.Principal;
import java.security.acl.SimpleAcl;

public class IterateACLEntries {

    public static void main(String[] args) throws Exception {
        String filePath = "myfile.txt";
        FileSecurity fileSecurity = new FileSecurity(filePath);

        // Create a user and a group
        Principal user = new Principal() {
            @Override
            public String getName() {
                return "user1";
            }
        };
        Group group = new Group() {
            @Override
            public String getName() {
                return "group1";
            }
        };

        // Create a permission for the group to read the file
        Permission readPermission = new PermissionImpl("java.io.FilePermission", filePath, "read");

        // Create a new ACL entry with the permission for the group
        AclEntry aclEntry = new AclEntryImpl(group, readPermission, true);

        // Add the ACL entry to the ACL
        Acl acl = new SimpleAcl();
        acl.add(aclEntry);

        // Set the ACL on the file
        fileSecurity.setAcl(acl);

        // Iterate over the ACL entries
        for (AclEntry entry : acl.getEntries()) {
            System.out.println(entry.