gcc/ada/7sintman.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --           S Y S T E M . I N T E R R U P T _ M A N A G E M E N T          --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --                                                                          --
  10 --             Copyright (C) 1991-2002, Florida State University            --
  11 --                                                                          --
  12 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University. It is --
  31 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  32 -- State University (http://www.gnat.com).                                  --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This is the default version of this package
  37
  38 --  This is a Sun OS (FSU THREADS) version of this package
  39
  40 --  PLEASE DO NOT add any dependences on other packages. ??? why not ???
  41 --  This package is designed to work with or without tasking support.
  42
  43 --  See the other warnings in the package specification before making
  44 --  any modifications to this file.
  45
  46 --  Make a careful study of all signals available under the OS, to see which
  47 --  need to be reserved, kept always unmasked, or kept always unmasked. Be on
  48 --  the lookout for special signals that may be used by the thread library.
  49
  50 --  Since this is a multi target file, the signal <-> exception mapping
  51 --  is simple minded. If you need a more precise and target specific
  52 --  signal handling, create a new s-intman.adb that will fit your needs.
  53
  54 --  This file assumes that:
  55 --
  56 --    SIGFPE, SIGILL, SIGSEGV and SIGBUS exist. They are mapped as follows:
  57 --      SIGPFE  => Constraint_Error
  58 --      SIGILL  => Program_Error
  59 --      SIGSEGV => Storage_Error
  60 --      SIGBUS  => Storage_Error
  61 --
  62 --    SIGINT exists and will be kept unmasked unless the pragma
  63 --     Unreserve_All_Interrupts is specified anywhere in the application.
  64 --
  65 --    System.OS_Interface contains the following:
  66 --      SIGADAABORT: the signal that will be used to abort tasks.
  67 --      Unmasked: the OS specific set of signals that should be unmasked in
  68 --                all the threads. SIGADAABORT is unmasked by
  69 --                default
  70 --      Reserved: the OS specific set of signals that are reserved.
  71
  72 with Interfaces.C;
  73 --  used for int and other types
  74
  75 with System.OS_Interface;
  76 --  used for various Constants, Signal and types
  77
  78 package body System.Interrupt_Management is
  79
  80    use Interfaces.C;
  81    use System.OS_Interface;
  82
  83    type Interrupt_List is array (Interrupt_ID range <>) of Interrupt_ID;
  84    Exception_Interrupts : constant Interrupt_List :=
  85      (SIGFPE, SIGILL, SIGSEGV, SIGBUS);
  86
  87    Unreserve_All_Interrupts : Interfaces.C.int;
  88    pragma Import
  89      (C, Unreserve_All_Interrupts, "__gl_unreserve_all_interrupts");
  90
  91    -----------------------
  92    -- Local Subprograms --
  93    -----------------------
  94
  95    procedure Notify_Exception (signo : Signal);
  96    --  This function identifies the Ada exception to be raised using
  97    --  the information when the system received a synchronous signal.
  98    --  Since this function is machine and OS dependent, different code
  99    --  has to be provided for different target.
 100
 101    ----------------------
 102    -- Notify_Exception --
 103    ----------------------
 104
 105    Signal_Mask : aliased sigset_t;
 106    --  The set of signals handled by Notify_Exception
 107
 108    procedure Notify_Exception (signo : Signal) is
 109       Result  : Interfaces.C.int;
 110
 111    begin
 112       --  With the __builtin_longjmp, the signal mask is not restored, so we
 113       --  need to restore it explicitly.
 114
 115       Result := pthread_sigmask (SIG_UNBLOCK, Signal_Mask'Access, null);
 116       pragma Assert (Result = 0);
 117
 118       --  Check that treatment of exception propagation here
 119       --  is consistent with treatment of the abort signal in
 120       --  System.Task_Primitives.Operations.
 121
 122       case signo is
 123          when SIGFPE =>
 124             raise Constraint_Error;
 125          when SIGILL =>
 126             raise Program_Error;
 127          when SIGSEGV =>
 128             raise Storage_Error;
 129          when SIGBUS =>
 130             raise Storage_Error;
 131          when others =>
 132             null;
 133       end case;
 134    end Notify_Exception;
 135
 136    ---------------------------
 137    -- Initialize_Interrupts --
 138    ---------------------------
 139
 140    --  Nothing needs to be done on this platform.
 141
 142    procedure Initialize_Interrupts is
 143    begin
 144       null;
 145    end Initialize_Interrupts;
 146
 147 -------------------------
 148 -- Package Elaboration --
 149 -------------------------
 150
 151 begin
 152    declare
 153       act     : aliased struct_sigaction;
 154       old_act : aliased struct_sigaction;
 155       Result  : Interfaces.C.int;
 156
 157    begin
 158       --  Need to call pthread_init very early because it is doing signal
 159       --  initializations.
 160
 161       pthread_init;
 162
 163       Abort_Task_Interrupt := SIGADAABORT;
 164
 165       act.sa_handler := Notify_Exception'Address;
 166
 167       act.sa_flags := 0;
 168
 169       --  On some targets, we set sa_flags to SA_NODEFER so that during the
 170       --  handler execution we do not change the Signal_Mask to be masked for
 171       --  the Signal.
 172
 173       --  This is a temporary fix to the problem that the Signal_Mask is
 174       --  not restored after the exception (longjmp) from the handler.
 175       --  The right fix should be made in sigsetjmp so that we save
 176       --  the Signal_Set and restore it after a longjmp.
 177
 178       --  Since SA_NODEFER is obsolete, instead we reset explicitly
 179       --  the mask in the exception handler.
 180
 181       Result := sigemptyset (Signal_Mask'Access);
 182       pragma Assert (Result = 0);
 183
 184       --  ??? For the same reason explained above, we can't mask these
 185       --  signals because otherwise we won't be able to catch more than
 186       --  one signal.
 187
 188       act.sa_mask := Signal_Mask;
 189
 190       Keep_Unmasked (Abort_Task_Interrupt) := True;
 191
 192       --  By keeping SIGINT unmasked, allow the user to do a Ctrl-C, but at
 193       --  the same time, disable the ability of handling this signal via
 194       --  package Ada.Interrupts.
 195
 196       --  The pragma Unreserve_All_Interrupts let the user the ability to
 197       --  change this behavior.
 198
 199       if Unreserve_All_Interrupts = 0 then
 200          Keep_Unmasked (SIGINT) := True;
 201       end if;
 202
 203       for J in Exception_Interrupts'Range loop
 204          Keep_Unmasked (Exception_Interrupts (J)) := True;
 205
 206          Result :=
 207            sigaction
 208            (Signal (Exception_Interrupts (J)), act'Unchecked_Access,
 209             old_act'Unchecked_Access);
 210          pragma Assert (Result = 0);
 211       end loop;
 212
 213       for J in Unmasked'Range loop
 214          Keep_Unmasked (Interrupt_ID (Unmasked (J))) := True;
 215       end loop;
 216
 217       Reserve := Keep_Unmasked or Keep_Masked;
 218
 219       for J in Reserved'Range loop
 220          Reserve (Interrupt_ID (Reserved (J))) := True;
 221       end loop;
 222
 223       --  We do not have Signal 0 in reality. We just use this value
 224       --  to identify non-existent signals (see s-intnam.ads). Therefore,
 225       --  Signal 0 should not be used in all signal related operations hence
 226       --  mark it as reserved.
 227
 228       Reserve (0) := True;
 229    end;
 230 end System.Interrupt_Management;