org.apache.hadoop.fs.XAttr.java Source code

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Here is the source code for org.apache.hadoop.fs.XAttr.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;

import java.util.Arrays;

import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;
import org.apache.hadoop.classification.InterfaceAudience;

/**
 * XAttr is the POSIX Extended Attribute model similar to that found in
 * traditional Operating Systems.  Extended Attributes consist of one
 * or more name/value pairs associated with a file or directory. Five
 * namespaces are defined: user, trusted, security, system and raw.
 *   1) USER namespace attributes may be used by any user to store
 *   arbitrary information. Access permissions in this namespace are
 *   defined by a file directory's permission bits. For sticky directories,
 *   only the owner and privileged user can write attributes.
 * <br>
 *   2) TRUSTED namespace attributes are only visible and accessible to
 *   privileged users. This namespace is available from both user space
 *   (filesystem API) and fs kernel.
 * <br>
 *   3) SYSTEM namespace attributes are used by the fs kernel to store
 *   system objects.  This namespace is only available in the fs
 *   kernel. It is not visible to users.
 * <br>
 *   4) SECURITY namespace attributes are used by the fs kernel for
 *   security features. It is not visible to users.
 * <br>
 *   5) RAW namespace attributes are used for internal system attributes that
 *   sometimes need to be exposed. Like SYSTEM namespace attributes they are
 *   not visible to the user except when getXAttr/getXAttrs is called on a file
 *   or directory in the /.reserved/raw HDFS directory hierarchy.  These
 *   attributes can only be accessed by the superuser.
 * <p>
 * @see <a href="http://en.wikipedia.org/wiki/Extended_file_attributes">
 * http://en.wikipedia.org/wiki/Extended_file_attributes</a>
 *
 */
@InterfaceAudience.Private
public class XAttr {

    public enum NameSpace {
        USER, TRUSTED, SECURITY, SYSTEM, RAW
    }

    private final NameSpace ns;
    private final String name;
    private final byte[] value;

    public static class Builder {
        private NameSpace ns = NameSpace.USER;
        private String name;
        private byte[] value;

        public Builder setNameSpace(NameSpace ns) {
            this.ns = ns;
            return this;
        }

        public Builder setName(String name) {
            this.name = name;
            return this;
        }

        public Builder setValue(byte[] value) {
            this.value = value;
            return this;
        }

        public XAttr build() {
            return new XAttr(ns, name, value);
        }
    }

    private XAttr(NameSpace ns, String name, byte[] value) {
        this.ns = ns;
        this.name = name;
        this.value = value;
    }

    public NameSpace getNameSpace() {
        return ns;
    }

    public String getName() {
        return name;
    }

    public byte[] getValue() {
        return value;
    }

    @Override
    public int hashCode() {
        return new HashCodeBuilder(811, 67).append(name).append(ns).append(value).toHashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (obj == this) {
            return true;
        }
        if (obj.getClass() != getClass()) {
            return false;
        }
        XAttr rhs = (XAttr) obj;
        return new EqualsBuilder().append(ns, rhs.ns).append(name, rhs.name).append(value, rhs.value).isEquals();
    }

    /**
     * Similar to {@link #equals(Object)}, except ignores the XAttr value.
     *
     * @param obj to compare equality
     * @return if the XAttrs are equal, ignoring the XAttr value
     */
    public boolean equalsIgnoreValue(Object obj) {
        if (obj == null) {
            return false;
        }
        if (obj == this) {
            return true;
        }
        if (obj.getClass() != getClass()) {
            return false;
        }
        XAttr rhs = (XAttr) obj;
        return new EqualsBuilder().append(ns, rhs.ns).append(name, rhs.name).isEquals();
    }

    @Override
    public String toString() {
        return "XAttr [ns=" + ns + ", name=" + name + ", value=" + Arrays.toString(value) + "]";
    }
}