/**
* 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 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 < 4) {// Prefix length is at least 4.
throw new HadoopIllegalArgumentException("An XAttr name must be " +
"prefixed with user/trusted/security/system, 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).toLowerCase();
if (prefix.equals(NameSpace.USER.toString().toLowerCase())) {
ns = NameSpace.USER;
} else if (prefix.equals(NameSpace.TRUSTED.toString().toLowerCase())) {
ns = NameSpace.TRUSTED;
} else if (prefix.equals(NameSpace.SYSTEM.toString().toLowerCase())) {
ns = NameSpace.SYSTEM;
} else if (prefix.equals(NameSpace.SECURITY.toString().toLowerCase())) {
ns = NameSpace.SECURITY;
} else {
throw new HadoopIllegalArgumentException("An XAttr name must be " +
"prefixed with user/trusted/security/system, followed by a '.'");
}
XAttr xAttr = (new XAttr.Builder()).setNameSpace(ns).setName(name.
substring(prefixIndex + 1)).setValue(value).build();
return xAttr;
}
/**
* 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 = getPrefixName(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 getPrefixName(XAttr xAttr) {
if (xAttr == null) {
return null;
}
String namespace = xAttr.getNameSpace().toString();
return namespace.toLowerCase() + "." + xAttr.getName();
}
/**
* 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;
}
}