org.digidoc4j.testutils.RestrictedFileWritingRule.java Source code

Introduction

Here is the source code for org.digidoc4j.testutils.RestrictedFileWritingRule.java

Source

/* DigiDoc4J library
*
* This software is released under either the GNU Library General Public
* License (see LICENSE.LGPL).
*
* Note that the only valid version of the LGPL license as far as this
* project is concerned is the original GNU Library General Public License
* Version 2.1, February 1999
*/

/*
 * Thanks to Aleksandr Zhuikov (http://aleksz-programming.blogspot.com.ee/2014/02/restricting-system-resource-access-in.html)
 */
package org.digidoc4j.testutils;

import java.security.Permission;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;

import org.apache.commons.lang.StringUtils;
import org.junit.rules.ExternalResource;

/**
 * JUnit rule for making sure that the code under test would not write anything to the file system.
 */
public class RestrictedFileWritingRule extends ExternalResource {

    private Collection<String> whiteList;

    public RestrictedFileWritingRule(String... whiteList) {
        this.whiteList = Arrays.asList(whiteList);
    }

    @Override
    protected void before() throws Throwable {
        super.before();
        System.setSecurityManager(new SecurityManager() {

            @Override
            public void checkWrite(String file) {
                if (!isAllowedToWrite(file)) {
                    throw new FileWritingRestrictedException();
                }
            }

            @Override
            public void checkPermission(Permission perm) {
                return;
            }
        });
    }

    @Override
    protected void after() {
        System.setSecurityManager(null); // or save and restore original
        super.after();
    }

    private boolean isAllowedToWrite(String file) {
        for (String prefix : whiteList) {
            if (StringUtils.startsWith(file, prefix)) {
                return true;
            }
        }
        return false;
    }

    /**
     * File writing operations happened when not allowed.
     */
    public static class FileWritingRestrictedException extends RuntimeException {
    }
}