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) 2005-2010, AdaCore                      --
  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 3,  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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package provides a target dependent non-blocking spawn function
  33 --  for use by the VMS GNAT.Expect package (g-expect-vms.adb). This package
  34 --  should not be directly with'ed by an application program.
  35
  36 --  This version is for Alpha/VMS
  37
  38 separate (GNAT.Expect)
  39 procedure Non_Blocking_Spawn
  40   (Descriptor  : out Process_Descriptor'Class;
  41    Command     : String;
  42    Args        : GNAT.OS_Lib.Argument_List;
  43    Buffer_Size : Natural := 4096;
  44    Err_To_Out  : Boolean := False)
  45 is
  46    function Alloc_Vfork_Blocks return Integer;
  47    pragma Import (C, Alloc_Vfork_Blocks, "decc$$alloc_vfork_blocks");
  48
  49    function Get_Vfork_Jmpbuf return System.Address;
  50    pragma Import (C, Get_Vfork_Jmpbuf, "decc$$get_vfork_jmpbuf");
  51
  52    function Get_Current_Invo_Context
  53      (Addr : System.Address) return Process_Id;
  54    pragma Import (C, Get_Current_Invo_Context,
  55      "LIB$GET_CURRENT_INVO_CONTEXT");
  56
  57    Pipe1, Pipe2, Pipe3 : aliased Pipe_Type;
  58
  59    Arg      : String_Access;
  60    Arg_List : aliased array (1 .. Args'Length + 2) of System.Address;
  61
  62    Command_With_Path : String_Access;
  63
  64 begin
  65    --  Create the rest of the pipes
  66
  67    Set_Up_Communications
  68      (Descriptor, Err_To_Out, Pipe1'Access, Pipe2'Access, Pipe3'Access);
  69
  70    Command_With_Path := Locate_Exec_On_Path (Command);
  71
  72    if Command_With_Path = null then
  73       raise Invalid_Process;
  74    end if;
  75
  76    --  Fork a new process (it is not possible to do this in a subprogram)
  77
  78    Descriptor.Pid :=
  79      (if Alloc_Vfork_Blocks >= 0
  80       then Get_Current_Invo_Context (Get_Vfork_Jmpbuf) else -1);
  81
  82    --  Are we now in the child
  83
  84    if Descriptor.Pid = Null_Pid then
  85
  86       --  Prepare an array of arguments to pass to C
  87
  88       Arg   := new String (1 .. Command_With_Path'Length + 1);
  89       Arg (1 .. Command_With_Path'Length) := Command_With_Path.all;
  90       Arg (Arg'Last)        := ASCII.NUL;
  91       Arg_List (1)          := Arg.all'Address;
  92
  93       for J in Args'Range loop
  94          Arg                     := new String (1 .. Args (J)'Length + 1);
  95          Arg (1 .. Args (J)'Length)  := Args (J).all;
  96          Arg (Arg'Last)              := ASCII.NUL;
  97          Arg_List (J + 2 - Args'First) := Arg.all'Address;
  98       end loop;
  99
 100       Arg_List (Arg_List'Last) := System.Null_Address;
 101
 102       --  This does not return on Unix systems
 103
 104       Set_Up_Child_Communications
 105         (Descriptor, Pipe1, Pipe2, Pipe3, Command_With_Path.all,
 106          Arg_List'Address);
 107    end if;
 108
 109    Free (Command_With_Path);
 110
 111    --  Did we have an error when spawning the child ?
 112
 113    if Descriptor.Pid < Null_Pid then
 114       raise Invalid_Process;
 115    else
 116       --  We are now in the parent process
 117
 118       Set_Up_Parent_Communications (Descriptor, Pipe1, Pipe2, Pipe3);
 119    end if;
 120
 121    --  Create the buffer
 122
 123    Descriptor.Buffer_Size := Buffer_Size;
 124
 125    if Buffer_Size /= 0 then
 126       Descriptor.Buffer := new String (1 .. Positive (Buffer_Size));
 127    end if;
 128 end Non_Blocking_Spawn;