org.apache.hadoop.hdfs.XAttrHelper.java Source code

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Here is the source code for org.apache.hadoop.hdfs.XAttrHelper.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.hdfs;

import java.util.List;
import java.util.Map;

import org.apache.hadoop.HadoopIllegalArgumentException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.XAttr;
import org.apache.hadoop.fs.XAttr.NameSpace;
import org.apache.hadoop.util.StringUtils;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

@InterfaceAudience.Private
public class XAttrHelper {

    /**
     * Build <code>XAttr</code> from xattr name with prefix.
     */
    public static XAttr buildXAttr(String name) {
        return buildXAttr(name, null);
    }

    /**
     * Build <code>XAttr</code> from name with prefix and value.
     * Name can not be null. Value can be null. The name and prefix
     * are validated.
     * Both name and namespace are case sensitive.
     */
    public static XAttr buildXAttr(String name, byte[] value) {
        Preconditions.checkNotNull(name, "XAttr name cannot be null.");

        final int prefixIndex = name.indexOf(".");
        if (prefixIndex < 3) {// Prefix length is at least 3.
            throw new HadoopIllegalArgumentException(
                    "An XAttr name must be " + "prefixed with user/trusted/security/system/raw, followed by a '.'");
        } else if (prefixIndex == name.length() - 1) {
            throw new HadoopIllegalArgumentException("XAttr name cannot be empty.");
        }

        NameSpace ns;
        final String prefix = name.substring(0, prefixIndex);
        if (StringUtils.equalsIgnoreCase(prefix, NameSpace.USER.toString())) {
            ns = NameSpace.USER;
        } else if (StringUtils.equalsIgnoreCase(prefix, NameSpace.TRUSTED.toString())) {
            ns = NameSpace.TRUSTED;
        } else if (StringUtils.equalsIgnoreCase(prefix, NameSpace.SYSTEM.toString())) {
            ns = NameSpace.SYSTEM;
        } else if (StringUtils.equalsIgnoreCase(prefix, NameSpace.SECURITY.toString())) {
            ns = NameSpace.SECURITY;
        } else if (StringUtils.equalsIgnoreCase(prefix, NameSpace.RAW.toString())) {
            ns = NameSpace.RAW;
        } else {
            throw new HadoopIllegalArgumentException(
                    "An XAttr name must be " + "prefixed with user/trusted/security/system/raw, followed by a '.'");
        }

        return (new XAttr.Builder()).setNameSpace(ns).setName(name.substring(prefixIndex + 1)).setValue(value)
                .build();
    }

    /**
     * Build xattr name with prefix as <code>XAttr</code> list.
     */
    public static List<XAttr> buildXAttrAsList(String name) {
        XAttr xAttr = buildXAttr(name);
        List<XAttr> xAttrs = Lists.newArrayListWithCapacity(1);
        xAttrs.add(xAttr);

        return xAttrs;
    }

    /**
     * Get value of first xattr from <code>XAttr</code> list
     */
    public static byte[] getFirstXAttrValue(List<XAttr> xAttrs) {
        byte[] value = null;
        XAttr xAttr = getFirstXAttr(xAttrs);
        if (xAttr != null) {
            value = xAttr.getValue();
            if (value == null) {
                value = new byte[0]; // xattr exists, but no value.
            }
        }
        return value;
    }

    /**
     * Get first xattr from <code>XAttr</code> list
     */
    public static XAttr getFirstXAttr(List<XAttr> xAttrs) {
        if (xAttrs != null && !xAttrs.isEmpty()) {
            return xAttrs.get(0);
        }

        return null;
    }

    /**
     * Build xattr map from <code>XAttr</code> list, the key is
     * xattr name with prefix, and value is xattr value.
     */
    public static Map<String, byte[]> buildXAttrMap(List<XAttr> xAttrs) {
        if (xAttrs == null) {
            return null;
        }
        Map<String, byte[]> xAttrMap = Maps.newHashMap();
        for (XAttr xAttr : xAttrs) {
            String name = getPrefixedName(xAttr);
            byte[] value = xAttr.getValue();
            if (value == null) {
                value = new byte[0];
            }
            xAttrMap.put(name, value);
        }

        return xAttrMap;
    }

    /**
     * Get name with prefix from <code>XAttr</code>
     */
    public static String getPrefixedName(XAttr xAttr) {
        if (xAttr == null) {
            return null;
        }

        return getPrefixedName(xAttr.getNameSpace(), xAttr.getName());
    }

    public static String getPrefixedName(XAttr.NameSpace ns, String name) {
        return StringUtils.toLowerCase(ns.toString()) + "." + name;
    }

    /**
     * Build <code>XAttr</code> list from xattr name list.
     */
    public static List<XAttr> buildXAttrs(List<String> names) {
        if (names == null || names.isEmpty()) {
            throw new HadoopIllegalArgumentException("XAttr names can not be " + "null or empty.");
        }

        List<XAttr> xAttrs = Lists.newArrayListWithCapacity(names.size());
        for (String name : names) {
            xAttrs.add(buildXAttr(name, null));
        }
        return xAttrs;
    }
}