gcc/ada/g-enblsp.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY 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) 2002 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 is maintained by Ada Core Technologies Inc (http://www.gnat.com).   --
  30 --                                                                          --
  31 ------------------------------------------------------------------------------
  32
  33 --  This is the default version. Used everywhere except VMS.
  34
  35 separate (GNAT.Expect)
  36 procedure Non_Blocking_Spawn
  37   (Descriptor  : out Process_Descriptor'Class;
  38    Command     : String;
  39    Args        : GNAT.OS_Lib.Argument_List;
  40    Buffer_Size : Natural := 4096;
  41    Err_To_Out  : Boolean := False)
  42 is
  43    function Fork return Process_Id;
  44    pragma Import (C, Fork, "__gnat_expect_fork");
  45    --  Starts a new process if possible.
  46    --  See the Unix command fork for more information. On systems that
  47    --  don't support this capability (Windows...), this command does
  48    --  nothing, and Fork will return Null_Pid.
  49
  50    Pipe1, Pipe2, Pipe3 : aliased Pipe_Type;
  51
  52    Arg      : String_Access;
  53    Arg_List : aliased array (1 .. Args'Length + 2) of System.Address;
  54
  55    Command_With_Path : String_Access;
  56
  57 begin
  58    --  Create the rest of the pipes
  59
  60    Set_Up_Communications
  61      (Descriptor, Err_To_Out, Pipe1'Access, Pipe2'Access, Pipe3'Access);
  62
  63    --  Fork a new process
  64
  65    Descriptor.Pid := Fork;
  66
  67    --  Are we now in the child (or, for Windows, still in the common
  68    --  process).
  69
  70    if Descriptor.Pid = Null_Pid then
  71
  72       Command_With_Path := Locate_Exec_On_Path (Command);
  73
  74       --  Prepare an array of arguments to pass to C
  75       Arg   := new String (1 .. Command_With_Path'Length + 1);
  76       Arg (1 .. Command_With_Path'Length) := Command_With_Path.all;
  77       Arg (Arg'Last)        := ASCII.Nul;
  78       Arg_List (1)          := Arg.all'Address;
  79
  80       for J in Args'Range loop
  81          Arg                     := new String (1 .. Args (J)'Length + 1);
  82          Arg (1 .. Args (J)'Length)  := Args (J).all;
  83          Arg (Arg'Last)              := ASCII.Nul;
  84          Arg_List (J + 2 - Args'First) := Arg.all'Address;
  85       end loop;
  86
  87       Arg_List (Arg_List'Last) := System.Null_Address;
  88
  89       --  This does not return on Unix systems
  90
  91       Set_Up_Child_Communications
  92         (Descriptor, Pipe1, Pipe2, Pipe3, Command_With_Path.all,
  93          Arg_List'Address);
  94
  95       Free (Command_With_Path);
  96    end if;
  97
  98    --  Did we have an error when spawning the child ?
  99
 100    if Descriptor.Pid < Null_Pid then
 101       null;
 102    else
 103       --  We are now in the parent process
 104
 105       Set_Up_Parent_Communications (Descriptor, Pipe1, Pipe2, Pipe3);
 106    end if;
 107
 108    --  Create the buffer
 109
 110    Descriptor.Buffer_Size := Buffer_Size;
 111
 112    if Buffer_Size /= 0 then
 113       Descriptor.Buffer := new String (1 .. Positive (Buffer_Size));
 114    end if;
 115 end Non_Blocking_Spawn;