gcc/ada/g-enblsp-vms-alpha.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --         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      --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --              Copyright (C) 2005 Ada Core Technologies, Inc.              --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This package provides a target dependent non-blocking spawn function
  35 --  for use by the VMS GNAT.Expect package (g-expect-vms.adb). This package
  36 --  should not be directly with'ed by an application program.
  37
  38 --  This version is for Alpha/VMS.
  39
  40 separate (GNAT.Expect)
  41 procedure Non_Blocking_Spawn
  42   (Descriptor  : out Process_Descriptor'Class;
  43    Command     : String;
  44    Args        : GNAT.OS_Lib.Argument_List;
  45    Buffer_Size : Natural := 4096;
  46    Err_To_Out  : Boolean := False)
  47 is
  48    function Alloc_Vfork_Blocks return Integer;
  49    pragma Import (C, Alloc_Vfork_Blocks, "decc$$alloc_vfork_blocks");
  50
  51    function Get_Vfork_Jmpbuf return System.Address;
  52    pragma Import (C, Get_Vfork_Jmpbuf, "decc$$get_vfork_jmpbuf");
  53
  54    function Get_Current_Invo_Context
  55      (Addr : System.Address) return Process_Id;
  56    pragma Import (C, Get_Current_Invo_Context,
  57      "LIB$GET_CURRENT_INVO_CONTEXT");
  58
  59    Pipe1, Pipe2, Pipe3 : aliased Pipe_Type;
  60
  61    Arg      : String_Access;
  62    Arg_List : aliased array (1 .. Args'Length + 2) of System.Address;
  63
  64    Command_With_Path : String_Access;
  65
  66 begin
  67    --  Create the rest of the pipes
  68
  69    Set_Up_Communications
  70      (Descriptor, Err_To_Out, Pipe1'Access, Pipe2'Access, Pipe3'Access);
  71
  72    Command_With_Path := Locate_Exec_On_Path (Command);
  73
  74    if Command_With_Path = null then
  75       raise Invalid_Process;
  76    end if;
  77
  78    --  Fork a new process. It's not possible to do this in a subprogram.
  79
  80    if Alloc_Vfork_Blocks >= 0 then
  81       Descriptor.Pid := Get_Current_Invo_Context (Get_Vfork_Jmpbuf);
  82    else
  83       Descriptor.Pid := -1;
  84    end if;
  85
  86    --  Are we now in the child (or, for Windows, still in the common
  87    --  process).
  88
  89    if Descriptor.Pid = Null_Pid then
  90       --  Prepare an array of arguments to pass to C
  91
  92       Arg   := new String (1 .. Command_With_Path'Length + 1);
  93       Arg (1 .. Command_With_Path'Length) := Command_With_Path.all;
  94       Arg (Arg'Last)        := ASCII.Nul;
  95       Arg_List (1)          := Arg.all'Address;
  96
  97       for J in Args'Range loop
  98          Arg                     := new String (1 .. Args (J)'Length + 1);
  99          Arg (1 .. Args (J)'Length)  := Args (J).all;
 100          Arg (Arg'Last)              := ASCII.Nul;
 101          Arg_List (J + 2 - Args'First) := Arg.all'Address;
 102       end loop;
 103
 104       Arg_List (Arg_List'Last) := System.Null_Address;
 105
 106       --  This does not return on Unix systems
 107
 108       Set_Up_Child_Communications
 109         (Descriptor, Pipe1, Pipe2, Pipe3, Command_With_Path.all,
 110          Arg_List'Address);
 111    end if;
 112
 113    Free (Command_With_Path);
 114
 115    --  Did we have an error when spawning the child ?
 116
 117    if Descriptor.Pid < Null_Pid then
 118       raise Invalid_Process;
 119    else
 120       --  We are now in the parent process
 121
 122       Set_Up_Parent_Communications (Descriptor, Pipe1, Pipe2, Pipe3);
 123    end if;
 124
 125    --  Create the buffer
 126
 127    Descriptor.Buffer_Size := Buffer_Size;
 128
 129    if Buffer_Size /= 0 then
 130       Descriptor.Buffer := new String (1 .. Positive (Buffer_Size));
 131    end if;
 132 end Non_Blocking_Spawn;