org.apache.hadoop.fs.permission.AclUtil.java Source code

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Here is the source code for org.apache.hadoop.fs.permission.AclUtil.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.fs.permission;

import java.util.Iterator;
import java.util.List;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

import com.google.common.collect.Lists;

/**
 * AclUtil contains utility methods for manipulating ACLs.
 */
@InterfaceAudience.LimitedPrivate({ "HDFS", "MapReduce" })
@InterfaceStability.Unstable
public final class AclUtil {

    /**
     * Given permissions and extended ACL entries, returns the full logical ACL.
     *
     * @param perm FsPermission containing permissions
     * @param entries List<AclEntry> containing extended ACL entries
     * @return List<AclEntry> containing full logical ACL
     */
    public static List<AclEntry> getAclFromPermAndEntries(FsPermission perm, List<AclEntry> entries) {
        List<AclEntry> acl = Lists.newArrayListWithCapacity(entries.size() + 3);

        // Owner entry implied by owner permission bits.
        acl.add(new AclEntry.Builder().setScope(AclEntryScope.ACCESS).setType(AclEntryType.USER)
                .setPermission(perm.getUserAction()).build());

        // All extended access ACL entries.
        boolean hasAccessAcl = false;
        Iterator<AclEntry> entryIter = entries.iterator();
        AclEntry curEntry = null;
        while (entryIter.hasNext()) {
            curEntry = entryIter.next();
            if (curEntry.getScope() == AclEntryScope.DEFAULT) {
                break;
            }
            hasAccessAcl = true;
            acl.add(curEntry);
        }

        // Mask entry implied by group permission bits, or group entry if there is
        // no access ACL (only default ACL).
        acl.add(new AclEntry.Builder().setScope(AclEntryScope.ACCESS)
                .setType(hasAccessAcl ? AclEntryType.MASK : AclEntryType.GROUP).setPermission(perm.getGroupAction())
                .build());

        // Other entry implied by other bits.
        acl.add(new AclEntry.Builder().setScope(AclEntryScope.ACCESS).setType(AclEntryType.OTHER)
                .setPermission(perm.getOtherAction()).build());

        // Default ACL entries.
        if (curEntry != null && curEntry.getScope() == AclEntryScope.DEFAULT) {
            acl.add(curEntry);
            while (entryIter.hasNext()) {
                acl.add(entryIter.next());
            }
        }

        return acl;
    }

    /**
     * Translates the given permission bits to the equivalent minimal ACL.
     *
     * @param perm FsPermission to translate
     * @return List<AclEntry> containing exactly 3 entries representing the owner,
     *   group and other permissions
     */
    public static List<AclEntry> getMinimalAcl(FsPermission perm) {
        return Lists.newArrayList(
                new AclEntry.Builder().setScope(AclEntryScope.ACCESS).setType(AclEntryType.USER)
                        .setPermission(perm.getUserAction()).build(),
                new AclEntry.Builder().setScope(AclEntryScope.ACCESS).setType(AclEntryType.GROUP)
                        .setPermission(perm.getGroupAction()).build(),
                new AclEntry.Builder().setScope(AclEntryScope.ACCESS).setType(AclEntryType.OTHER)
                        .setPermission(perm.getOtherAction()).build());
    }

    /**
     * Checks if the given entries represent a minimal ACL (contains exactly 3
     * entries).
     *
     * @param entries List<AclEntry> entries to check
     * @return boolean true if the entries represent a minimal ACL
     */
    public static boolean isMinimalAcl(List<AclEntry> entries) {
        return entries.size() == 3;
    }

    /**
     * There is no reason to instantiate this class.
     */
    private AclUtil() {
    }
}