class FileStat
  S_IFMTMSK = 0170000     # bit mask for the file type bit fields
  S_IFSOCK  = 0140000     # socket
  S_IFLNK   = 0120000     # symbolic link
  S_IFREG   = 0100000     # regular file
  S_IFBLK   = 0060000     # block device
  S_IFDIR   = 0040000     # directory
  S_IFCHR   = 0020000     # character device
  S_IFIFO   = 0010000     # FIFO
  S_ISUID   = 0004000     # set UID bit
  S_ISGID   = 0002000     # set-group-ID bit
  S_ISVTX   = 0001000     # sticky bit
  S_IRWXU   = 00700       # mask for file owner permissions
  S_IRUSR   = 00400       # owner has read permission
  S_IWUSR   = 00200       # owner has write permission
  S_IXUSR   = 00100       # owner has execute permission
  S_IRWXG   = 00070       # mask for group permissions
  S_IRGRP   = 00040       # group has read permission
  S_IWGRP   = 00020       # group has write permission
  S_IXGRP   = 00010       # group has execute permission
  S_IRWXO   = 00007       # mask for permissions for others (not in group)
  S_IROTH   = 00004       # others have read permission
  S_IWOTH   = 00002       # others have write permission
  S_IXOTH   = 00001       # others have execute permission
 
  FILE_TYPES =  {
                 S_IFBLK  => 'b',
                 S_IFCHR  => 'c',
                 S_IFDIR  => 'd',
                 S_IFREG  => '-',
                 S_IFIFO  => 'p',
                 S_IFLNK  => 'l',
                 S_IFSOCK => 's',
                }

  SET_ID_STICKY = [
                   [S_ISUID,'s'],
                   [S_ISGID,'s'],
                   [S_ISVTX,'t'],
                  ]
                    
  def initialize(mode)
    @mode = mode
  end
  
  def modeStr
    self.class.modeStr(@mode)
  end

  def S_IFMT
    self.class.S_IFMT(@mode)
  end
    
  def S_IMODE
    self.class.S_IMODE(@mode)
  end
    
  def S_ISBLK
    self.class.S_ISBLK(@mode)
  end
    
  def S_ISCHR
    self.class.S_ISCHR(@mode)
  end
    
  def S_ISDIR
    self.class.S_ISDIR(@mode)
  end
    
  def S_ISFIFO
    self.class.S_ISFIFO(@mode)
  end
    
  def S_ISLNK
    self.class.S_ISLNK(@mode)
  end
    
  def S_ISREG
    self.class.S_ISREG(@mode)
  end
    
  def S_ISSOCK
    self.class.S_ISSOCK(@mode)
  end
  
  def self.modeStr(mode)
    ret = '----------'
    ret[0] = FILE_TYPES[mode & S_IFMTMSK]
    bit = 0
    ['USR','GRP','OTH'].each do |who|
      ['r','w','x'].each do |access|
        bit += 1
        if mode & eval("S_I#{access.upcase}#{who}") == eval("S_I#{access.upcase}#{who}")
          ret[bit] = access
        end
      end
    end
    bit = 0
    SET_ID_STICKY.each do |setid,sticky|
      bit += 3
      if mode & eval("#{setid}") == eval("#{setid}")
        if ret[bit,1] == 'x'
          ret[bit] = sticky.upcase
        else
          ret[bit] = sticky
        end
      end
    end
    return ret
  end
  
  def self.S_IFMT(mode)
    return (mode & S_IFMTMSK)
  end
  
  def self.S_IMODE(mode)
    return (mode & (S_IRWXU + S_IRWXG + S_IRWXO))
  end
  
  def self.S_ISBLK(mode)
    return (mode & S_IFMTMSK) == S_IFBLK
  end
    
  def self.S_ISCHR(mode)
    return (mode & S_IFMTMSK) == S_IFCHR
  end

  def self.S_ISDIR(mode)
    return (mode & S_IFMTMSK) == S_IFDIR
  end
    
  def self.S_ISFIFO(mode)
    return (mode & S_IFMTMSK) == S_IFIFO
  end
    
  def self.S_ISLNK(mode)
    return (mode & S_IFMTMSK) == S_IFLNK
  end
    
  def self.S_ISREG(mode)
    return (mode & S_IFMTMSK) == S_IFREG
  end
    
  def self.S_ISSOCK(mode)
    return (mode & S_IFMTMSK) == S_IFSOCK
  end

end