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

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--         G N A T . E X P E C T . N O N _ B L O C K I N G _ S P A W N      --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--                    Copyright (C) 2005-2010, 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.      --

--                                                                          --

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

--  This package provides a target dependent non-blocking spawn function

--  for use by the VMS GNAT.Expect package (g-expect-vms.adb). This package

--  should not be directly with'ed by an application program.

--  This version is for Alpha/VMS

separate (GNAT.Expect)

procedure Non_Blocking_Spawn

  (Descriptor  : out Process_Descriptor'Class;

   Command     : String;

   Args        : GNAT.OS_Lib.Argument_List;

   Buffer_Size : Natural := 4096;

   Err_To_Out  : Boolean := False)

is

   function Alloc_Vfork_Blocks return Integer;

   pragma Import (C, Alloc_Vfork_Blocks, "decc$$alloc_vfork_blocks");

   function Get_Vfork_Jmpbuf return System.Address;

   pragma Import (C, Get_Vfork_Jmpbuf, "decc$$get_vfork_jmpbuf");

   function Get_Current_Invo_Context

     (Addr : System.Address) return Process_Id;

   pragma Import (C, Get_Current_Invo_Context,

     "LIB$GET_CURRENT_INVO_CONTEXT");

   Pipe1, Pipe2, Pipe3 : aliased Pipe_Type;

   Arg      : String_Access;

   Arg_List : aliased array (1 .. Args'Length + 2) of System.Address;

   Command_With_Path : String_Access;

begin

   --  Create the rest of the pipes

   Set_Up_Communications

     (Descriptor, Err_To_Out, Pipe1'Access, Pipe2'Access, Pipe3'Access);

   Command_With_Path := Locate_Exec_On_Path (Command);

   if Command_With_Path = null then

      raise Invalid_Process;

   end if;

   --  Fork a new process (it is not possible to do this in a subprogram)

   Descriptor.Pid :=

     (if Alloc_Vfork_Blocks >= 0

      then Get_Current_Invo_Context (Get_Vfork_Jmpbuf) else -1);

   --  Are we now in the child

   if Descriptor.Pid = Null_Pid then

      --  Prepare an array of arguments to pass to C

      Arg   := new String (1 .. Command_With_Path'Length + 1);

      Arg (1 .. Command_With_Path'Length) := Command_With_Path.all;

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

      Arg_List (1)          := Arg.all'Address;

      for J in Args'Range loop

         Arg                     := new String (1 .. Args (J)'Length + 1);

         Arg (1 .. Args (J)'Length)  := Args (J).all;

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

         Arg_List (J + 2 - Args'First) := Arg.all'Address;

      end loop;

      Arg_List (Arg_List'Last) := System.Null_Address;

      --  This does not return on Unix systems

      Set_Up_Child_Communications

        (Descriptor, Pipe1, Pipe2, Pipe3, Command_With_Path.all,

         Arg_List'Address);

   end if;

   Free (Command_With_Path);

   --  Did we have an error when spawning the child ?

   if Descriptor.Pid < Null_Pid then

      raise Invalid_Process;

   else

      --  We are now in the parent process

      Set_Up_Parent_Communications (Descriptor, Pipe1, Pipe2, Pipe3);

   end if;

   --  Create the buffer

   Descriptor.Buffer_Size := Buffer_Size;

   if Buffer_Size /= 0 then

      Descriptor.Buffer := new String (1 .. Positive (Buffer_Size));

   end if;

end Non_Blocking_Spawn;