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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--              A D A . E N V I R O N M E N T _ V A R I A B L E S           --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--            Copyright (C) 2009, Free Software Foundation, Inc.            --

--                                                                          --

-- 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 System;

with Interfaces.C.Strings;

with Ada.Unchecked_Deallocation;

package body Ada.Environment_Variables is

   -----------

   -- Clear --

   -----------

   procedure Clear (Name : String) is

      procedure Clear_Env_Var (Name : System.Address);

      pragma Import (C, Clear_Env_Var, "__gnat_unsetenv");

      F_Name  : String (1 .. Name'Length + 1);

   begin

      F_Name (1 .. Name'Length) := Name;

      F_Name (F_Name'Last)      := ASCII.NUL;

      Clear_Env_Var (F_Name'Address);

   end Clear;

   -----------

   -- Clear --

   -----------

   procedure Clear is

      procedure Clear_Env;

      pragma Import (C, Clear_Env, "__gnat_clearenv");

   begin

      Clear_Env;

   end Clear;

   ------------

   -- Exists --

   ------------

   function Exists (Name : String) return Boolean is

      use System;

      procedure Get_Env_Value_Ptr (Name, Length, Ptr : Address);

      pragma Import (C, Get_Env_Value_Ptr, "__gnat_getenv");

      Env_Value_Ptr    : aliased Address;

      Env_Value_Length : aliased Integer;

      F_Name           : aliased String (1 .. Name'Length + 1);

   begin

      F_Name (1 .. Name'Length) := Name;

      F_Name (F_Name'Last)      := ASCII.NUL;

      Get_Env_Value_Ptr

        (F_Name'Address, Env_Value_Length'Address, Env_Value_Ptr'Address);

      if Env_Value_Ptr = System.Null_Address then

         return False;

      end if;

      return True;

   end Exists;

   -------------

   -- Iterate --

   -------------

   procedure Iterate

     (Process : not null access procedure (Name, Value : String))

   is

      use Interfaces.C.Strings;

      type C_String_Array is array (Natural) of aliased chars_ptr;

      type C_String_Array_Access is access C_String_Array;

      function Get_Env return C_String_Array_Access;

      pragma Import (C, Get_Env, "__gnat_environ");

      type String_Access is access all String;

      procedure Free is new Ada.Unchecked_Deallocation (String, String_Access);

      Env_Length : Natural := 0;

      Env        : constant C_String_Array_Access := Get_Env;

   begin

      --  If the environment is null return directly

      if Env = null then

         return;

      end if;

      --  First get the number of environment variables

      loop

         exit when Env (Env_Length) = Null_Ptr;

         Env_Length := Env_Length + 1;

      end loop;

      declare

         Env_Copy : array (1 .. Env_Length) of String_Access;

      begin

         --  Copy the environment

         for Iterator in 1 ..  Env_Length loop

            Env_Copy (Iterator) := new String'(Value (Env (Iterator - 1)));

         end loop;

         --  Iterate on the environment copy

         for Iterator in 1 .. Env_Length loop

            declare

               Current_Var : constant String := Env_Copy (Iterator).all;

               Value_Index : Natural := Env_Copy (Iterator)'First;

            begin

               loop

                  exit when Current_Var (Value_Index) = '=';

                  Value_Index := Value_Index + 1;

               end loop;

               Process

                 (Current_Var (Current_Var'First .. Value_Index - 1),

                  Current_Var (Value_Index + 1 .. Current_Var'Last));

            end;

         end loop;

         --  Free the copy of the environment

         for Iterator in 1 .. Env_Length loop

            Free (Env_Copy (Iterator));

         end loop;

      end;

   end Iterate;

   ---------

   -- Set --

   ---------

   procedure Set (Name : String; Value : String) is

      F_Name  : String (1 .. Name'Length + 1);

      F_Value : String (1 .. Value'Length + 1);

      procedure Set_Env_Value (Name, Value : System.Address);

      pragma Import (C, Set_Env_Value, "__gnat_setenv");

   begin

      F_Name (1 .. Name'Length) := Name;

      F_Name (F_Name'Last)      := ASCII.NUL;

      F_Value (1 .. Value'Length) := Value;

      F_Value (F_Value'Last)      := ASCII.NUL;

      Set_Env_Value (F_Name'Address, F_Value'Address);

   end Set;

   -----------

   -- Value --

   -----------

   function Value (Name : String) return String is

      use System;

      procedure Get_Env_Value_Ptr (Name, Length, Ptr : Address);

      pragma Import (C, Get_Env_Value_Ptr, "__gnat_getenv");

      procedure Strncpy (Astring_Addr, Cstring : Address; N : Integer);

      pragma Import (C, Strncpy, "strncpy");

      Env_Value_Ptr    : aliased Address;

      Env_Value_Length : aliased Integer;

      F_Name           : aliased String (1 .. Name'Length + 1);

   begin

      F_Name (1 .. Name'Length) := Name;

      F_Name (F_Name'Last)      := ASCII.NUL;

      Get_Env_Value_Ptr

        (F_Name'Address, Env_Value_Length'Address, Env_Value_Ptr'Address);

      if Env_Value_Ptr = System.Null_Address then

         raise Constraint_Error;

      end if;

      if Env_Value_Length > 0 then

         declare

            Result : aliased String (1 .. Env_Value_Length);

         begin

            Strncpy (Result'Address, Env_Value_Ptr, Env_Value_Length);

            return Result;

         end;

      else

         return "";

      end if;

   end Value;

end Ada.Environment_Variables;