------------------------------------------------------------------------------
--                                                                          --
--                         GNAT LIBRARY COMPONENTS                          --
--                                                                          --
--                             G N A T . T T Y                              --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--                     Copyright (C) 2002-2020, AdaCore                     --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

with Interfaces.C.Strings; use Interfaces.C.Strings;

package body GNAT.TTY is

   use System;

   procedure Check_TTY (Handle : TTY_Handle);
   --  Check the validity of Handle. Raise Program_Error if ttys are not
   --  supported. Raise Constraint_Error if Handle is an invalid handle.

   ------------------
   -- Allocate_TTY --
   ------------------

   procedure Allocate_TTY (Handle : out TTY_Handle) is
      function Internal return System.Address;
      pragma Import (C, Internal, "__gnat_new_tty");

   begin
      if not TTY_Supported then
         raise Program_Error;
      end if;

      Handle.Handle := Internal;
   end Allocate_TTY;

   ---------------
   -- Check_TTY --
   ---------------

   procedure Check_TTY (Handle : TTY_Handle) is
   begin
      if not TTY_Supported then
         raise Program_Error;
      elsif Handle.Handle = System.Null_Address then
         raise Constraint_Error;
      end if;
   end Check_TTY;

   ---------------
   -- Close_TTY --
   ---------------

   procedure Close_TTY (Handle : in out TTY_Handle) is
      procedure Internal (Handle : System.Address);
      pragma Import (C, Internal, "__gnat_close_tty");
   begin
      Check_TTY (Handle);
      Internal (Handle.Handle);
      Handle.Handle := System.Null_Address;
   end Close_TTY;

   ---------------
   -- Reset_TTY --
   ---------------

   procedure Reset_TTY (Handle : TTY_Handle) is
      procedure Internal (Handle : System.Address);
      pragma Import (C, Internal, "__gnat_reset_tty");
   begin
      Check_TTY (Handle);
      Internal (Handle.Handle);
   end Reset_TTY;

   --------------------
   -- TTY_Descriptor --
   --------------------

   function TTY_Descriptor
     (Handle : TTY_Handle) return GNAT.OS_Lib.File_Descriptor
   is
      function Internal
        (Handle : System.Address) return GNAT.OS_Lib.File_Descriptor;
      pragma Import (C, Internal, "__gnat_tty_fd");
   begin
      Check_TTY (Handle);
      return Internal (Handle.Handle);
   end TTY_Descriptor;

   --------------
   -- TTY_Name --
   --------------

   function TTY_Name (Handle : TTY_Handle) return String is
      function Internal (Handle : System.Address) return chars_ptr;
      pragma Import (C, Internal, "__gnat_tty_name");
   begin
      Check_TTY (Handle);
      return Value (Internal (Handle.Handle));
   end TTY_Name;

   -------------------
   -- TTY_Supported --
   -------------------

   function TTY_Supported return Boolean is
      function Internal return Integer;
      pragma Import (C, Internal, "__gnat_tty_supported");
   begin
      return Internal /= 0;
   end TTY_Supported;

end GNAT.TTY;
