001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.hadoop.fs.permission;
019    
020    import org.apache.hadoop.classification.InterfaceAudience;
021    import org.apache.hadoop.classification.InterfaceStability;
022    
023    /**
024     * File system actions, e.g. read, write, etc.
025     */
026    @InterfaceAudience.Public
027    @InterfaceStability.Stable
028    public enum FsAction {
029      // POSIX style
030      NONE("---"),
031      EXECUTE("--x"),
032      WRITE("-w-"),
033      WRITE_EXECUTE("-wx"),
034      READ("r--"),
035      READ_EXECUTE("r-x"),
036      READ_WRITE("rw-"),
037      ALL("rwx");
038    
039      /** Retain reference to value array. */
040      private final static FsAction[] vals = values();
041    
042      /** Symbolic representation */
043      public final String SYMBOL;
044    
045      private FsAction(String s) {
046        SYMBOL = s;
047      }
048    
049      /**
050       * Return true if this action implies that action.
051       * @param that
052       */
053      public boolean implies(FsAction that) {
054        if (that != null) {
055          return (ordinal() & that.ordinal()) == that.ordinal();
056        }
057        return false;
058      }
059    
060      /** AND operation. */
061      public FsAction and(FsAction that) {
062        return vals[ordinal() & that.ordinal()];
063      }
064      /** OR operation. */
065      public FsAction or(FsAction that) {
066        return vals[ordinal() | that.ordinal()];
067      }
068      /** NOT operation. */
069      public FsAction not() {
070        return vals[7 - ordinal()];
071      }
072    
073      /**
074       * Get the FsAction enum for String representation of permissions
075       * 
076       * @param permission
077       *          3-character string representation of permission. ex: rwx
078       * @return Returns FsAction enum if the corresponding FsAction exists for permission.
079       *         Otherwise returns null
080       */
081      public static FsAction getFsAction(String permission) {
082        for (FsAction fsAction : vals) {
083          if (fsAction.SYMBOL.equals(permission)) {
084            return fsAction;
085          }
086        }
087        return null;
088      }
089    }