content: /*
   * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package com.termux.shared.file.filesystem;
  
  import static com.termux.shared.file.filesystem.FilePermission.*;
  
  import java.util.*;
  
  /**
   * This class consists exclusively of static methods that operate on sets of
   * {@link FilePermission} objects.
   *
   * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r3:libcore/ojluni/src/main/java/java/nio/file/attribute/PosixFilePermissions.java
   *
   * @since 1.7
   */
  
  public final class FilePermissions {
      private FilePermissions() { }
  
      // Write string representation of permission bits to {@code sb}.
      private static void writeBits(StringBuilder sb, boolean r, boolean w, boolean x) {
          if (r) {
              sb.append('r');
          } else {
              sb.append('-');
          }
          if (w) {
              sb.append('w');
          } else {
              sb.append('-');
          }
          if (x) {
              sb.append('x');
          } else {
              sb.append('-');
          }
      }
  
      /**
       * Returns the {@code String} representation of a set of permissions. It
       * is guaranteed that the returned {@code String} can be parsed by the
       * {@link #fromString} method.
       *
       * <p> If the set contains {@code null} or elements that are not of type
       * {@code FilePermission} then these elements are ignored.
       *
       * @param   perms
       *          the set of permissions
       *
       * @return  the string representation of the permission set
       */
      public static String toString(Set<FilePermission> perms) {
          StringBuilder sb = new StringBuilder(9);
          writeBits(sb, perms.contains(OWNER_READ), perms.contains(OWNER_WRITE),
              perms.contains(OWNER_EXECUTE));
          writeBits(sb, perms.contains(GROUP_READ), perms.contains(GROUP_WRITE),
              perms.contains(GROUP_EXECUTE));
          writeBits(sb, perms.contains(OTHERS_READ), perms.contains(OTHERS_WRITE),
              perms.contains(OTHERS_EXECUTE));
          return sb.toString();
      }
  
      private static boolean isSet(char c, char setValue) {
          if (c == setValue)
              return true;
          if (c == '-')
              return false;
          throw new IllegalArgumentException("Invalid mode");
      }
      private static boolean isR(char c) { return isSet(c, 'r'); }
      private static boolean isW(char c) { return isSet(c, 'w'); }
      private static boolean isX(char c) { return isSet(c, 'x'); }
  
      /**
       * Returns the set of permissions corresponding to a given {@code String}
       * representation.
       *
       * <p> The {@code perms} parameter is a {@code String} representing the
       * permissions. It has 9 characters that are interpreted as three sets of
       * three. The first set refers to the owner's permissions; the next to the
       * group permissions and the last to others. Within each set, the first
       * character is {@code 'r'} to indicate permission to read, the second
       * character is {@code 'w'} to indicate permission to write, and the third
       * character is {@code 'x'} for execute permission. Where a permission is
       * not set then the corresponding character is set to {@code '-'}.
       *
       * <p> <b>Usage Example:</b>
       * Suppose we require the set of permissions that indicate the owner has read,
       * write, and execute permissions, the group has read and execute permissions
       * and others have none.
       * <pre>
       *   Set&lt;FilePermission&gt; perms = FilePermissions.fromString("rwxr-x---");
       * </pre>
       *
       * @param   perms
       *          string representing a set of permissions
       *
       * @return  the resulting set of permissions
       *
       * @throws  IllegalArgumentException
       *          if the string cannot be converted to a set of permissions
       *
       * @see #toString(Set)
       */
      public static Set<FilePermission> fromString(String perms) {
          if (perms.length() != 9)
              throw new IllegalArgumentException("Invalid mode");
          Set<FilePermission> result = EnumSet.noneOf(FilePermission.class);
          if (isR(perms.charAt(0))) result.add(OWNER_READ);
          if (isW(perms.charAt(1))) result.add(OWNER_WRITE);
          if (isX(perms.charAt(2))) result.add(OWNER_EXECUTE);
          if (isR(perms.charAt(3))) result.add(GROUP_READ);
          if (isW(perms.charAt(4))) result.add(GROUP_WRITE);
          if (isX(perms.charAt(5))) result.add(GROUP_EXECUTE);
          if (isR(perms.charAt(6))) result.add(OTHERS_READ);
          if (isW(perms.charAt(7))) result.add(OTHERS_WRITE);
          if (isX(perms.charAt(8))) result.add(OTHERS_EXECUTE);
          return result;
      }
  
  }
  