/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.driver.unix.aix;
   
   import java.util.HashMap;
   import java.util.Map;
   
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.util.ExecutingCommand;
  import oshi.util.ParseUtil;
  import oshi.util.tuples.Pair;
  
  /**
   * Utility to query ls
   */
  @ThreadSafe
  public final class Ls {
  
      private Ls() {
      }
  
      /**
       * Query {@code ls} to get parition info
       *
       * @return A map of device name to a major-minor pair
       */
      public static Map<String, Pair<Integer, Integer>> queryDeviceMajorMinor() {
          // Map major and minor from ls
          /*-
           $ ls -l /dev
          brw-rw----  1 root system 10,  5 Sep 12  2017 hd2
          brw-------  1 root system 20,  0 Jun 28  1970 hdisk0
           */
          Map<String, Pair<Integer, Integer>> majMinMap = new HashMap<>();
          for (String s : ExecutingCommand.runNative("ls -l /dev")) {
              // Filter to block devices
              if (!s.isEmpty() && s.charAt(0) == 'b') {
                  // Device name is last space-delim string
                  int idx = s.lastIndexOf(' ');
                  if (idx > 0 && idx < s.length()) {
                      String device = s.substring(idx + 1);
                      int major = ParseUtil.getNthIntValue(s, 2);
                      int minor = ParseUtil.getNthIntValue(s, 3);
                      majMinMap.put(device, new Pair<>(major, minor));
                  }
              }
          }
          return majMinMap;
      }
  }