gcc/ada/5uintman.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 a Sun OS (FSU THREADS) version of this package
  37
  38 --  PLEASE DO NOT add any dependences on other packages. ??? why not ???
  39 --  This package is designed to work with or without tasking support.
  40
  41 --  Make a careful study of all signals available under the OS, to see which
  42 --  need to be reserved, kept always unmasked, or kept always unmasked. Be on
  43 --  the lookout for special signals that may be used by the thread library.
  44
  45 with Interfaces.C;
  46 --  used for int
  47
  48 with System.Error_Reporting;
  49 --  used for Shutdown
  50
  51 with System.OS_Interface;
  52 --  used for various Constants, Signal and types
  53
  54 package body System.Interrupt_Management is
  55
  56    use Interfaces.C;
  57    use System.Error_Reporting;
  58    use System.OS_Interface;
  59
  60    type Interrupt_List is array (Interrupt_ID range <>) of Interrupt_ID;
  61    Exception_Interrupts : constant Interrupt_List :=
  62      (SIGFPE, SIGILL, SIGSEGV);
  63
  64    Unreserve_All_Interrupts : Interfaces.C.int;
  65    pragma Import
  66      (C, Unreserve_All_Interrupts, "__gl_unreserve_all_interrupts");
  67
  68    -----------------------
  69    -- Local Subprograms --
  70    -----------------------
  71
  72    procedure Notify_Exception
  73      (signo   : Signal;
  74       info    : access siginfo_t;
  75       context : access struct_sigcontext);
  76    --  This function identifies the Ada exception to be raised using
  77    --  the information when the system received a synchronous signal.
  78    --  Since this function is machine and OS dependent, different code
  79    --  has to be provided for different target.
  80
  81    ----------------------
  82    -- Notify_Exception --
  83    ----------------------
  84
  85    --  The following code is intended for SunOS on Sparcstation.
  86
  87    procedure Notify_Exception
  88      (signo   : Signal;
  89       info    : access siginfo_t;
  90       context : access struct_sigcontext)
  91    is
  92    begin
  93       --  As long as we are using a longjmp to return control to the
  94       --  exception handler on the runtime stack, we are safe. The original
  95       --  signal mask (the one we had before coming into this signal catching
  96       --  function) will be restored by the longjmp. Therefore, raising
  97       --  an exception in this handler should be a safe operation.
  98
  99       --  Check that treatment of exception propagation here
 100       --  is consistent with treatment of the abort signal in
 101       --  System.Task_Primitives.Operations.
 102
 103       case signo is
 104          when SIGFPE =>
 105             case info.si_code is
 106                when FPE_INTOVF_TRAP   |
 107                     FPE_STARTSIG_TRAP |
 108                     FPE_INTDIV_TRAP   |
 109                     FPE_FLTDIV_TRAP   |
 110                     FPE_FLTUND_TRAP   |
 111                     FPE_FLTOPERR_TRAP |
 112                     FPE_FLTOVF_TRAP =>
 113                   raise Constraint_Error;
 114
 115                when others =>
 116                   pragma Assert (Shutdown ("Unexpected SIGFPE signal"));
 117                   null;
 118             end case;
 119
 120          when SIGILL =>
 121             case info.si_code is
 122                when ILL_STACK           |
 123                     ILL_ILLINSTR_FAULT  |
 124                     ILL_PRIVINSTR_FAULT =>
 125                   raise Constraint_Error;
 126
 127                when others =>
 128                   pragma Assert (Shutdown ("Unexpected SIGILL signal"));
 129                   null;
 130             end case;
 131
 132          when SIGSEGV =>
 133
 134             --  was caused by accessing a null pointer.
 135
 136 --  ???? Origin of this code is unclear, may be broken ???
 137
 138             if context.sc_o0 in 0 .. 16#2000# then
 139                raise Constraint_Error;
 140             else
 141                raise Storage_Error;
 142             end if;
 143
 144          when others =>
 145             pragma Assert (Shutdown ("Unexpected signal"));
 146             null;
 147       end case;
 148    end Notify_Exception;
 149
 150    ---------------------------
 151    -- Initialize_Interrupts --
 152    ---------------------------
 153
 154    --  Nothing needs to be done on this platform
 155
 156    procedure Initialize_Interrupts is
 157    begin
 158       null;
 159    end Initialize_Interrupts;
 160
 161 -------------------------
 162 -- Package Elaboration --
 163 -------------------------
 164
 165 begin
 166    declare
 167       act     : aliased struct_sigaction;
 168       old_act : aliased struct_sigaction;
 169       mask    : aliased sigset_t;
 170       Result  : Interfaces.C.int;
 171
 172    begin
 173       --  Need to call pthread_init very early because it is doing signal
 174       --  initializations.
 175
 176       pthread_init;
 177
 178       --  Change the following assignment to use another signal for task abort.
 179       --  For example, SIGTERM might be a good one if SIGABRT is required for
 180       --  use elsewhere.
 181
 182       Abort_Task_Interrupt := SIGABRT;
 183
 184       act.sa_handler := Notify_Exception'Address;
 185
 186       --  Set sa_flags to SA_NODEFER so that during the handler execution
 187       --  we do not change the Signal_Mask to be masked for the Signal.
 188       --  This is a temporary fix to the problem that the Signal_Mask is
 189       --  not restored after the exception (longjmp) from the handler.
 190       --  The right fix should be made in sigsetjmp so that we save
 191       --  the Signal_Set and restore it after a longjmp.
 192
 193       --  In that case, this field should be changed back to 0. ???
 194
 195       act.sa_flags := 16;
 196
 197       Result := sigemptyset (mask'Access);
 198       pragma Assert (Result = 0);
 199
 200       for J in Exception_Interrupts'Range loop
 201          Result := sigaddset (mask'Access, Signal (Exception_Interrupts (J)));
 202          pragma Assert (Result = 0);
 203       end loop;
 204
 205       act.sa_mask := mask;
 206
 207       for J in Exception_Interrupts'Range loop
 208          Keep_Unmasked (Exception_Interrupts (J)) := True;
 209
 210          Result :=
 211            sigaction
 212            (Signal (Exception_Interrupts (J)),
 213             act'Unchecked_Access,
 214             old_act'Unchecked_Access);
 215          pragma Assert (Result = 0);
 216       end loop;
 217
 218       Keep_Unmasked (Abort_Task_Interrupt) := True;
 219       Keep_Unmasked (SIGALRM) := True;
 220       Keep_Unmasked (SIGSTOP) := True;
 221       Keep_Unmasked (SIGKILL) := True;
 222
 223       --  By keeping SIGINT unmasked, allow the user to do a Ctrl-C, but at
 224       --  the same time, disable the ability of handling this signal using
 225       --  package Ada.Interrupts.
 226
 227       --  The pragma Unreserve_All_Interrupts allows the user the ability to
 228       --  change this behavior.
 229
 230       if Unreserve_All_Interrupts = 0 then
 231          Keep_Unmasked (SIGINT) := True;
 232       end if;
 233
 234       --  Reserve this not to interfere with thread scheduling
 235
 236       --  ??? consider adding this to interrupt exceptions
 237       --  Keep_Unmasked (SIGALRM) := True;
 238
 239       --  An earlier version had a comment about SIGALRM needing to be unmasked
 240       --  in at least one thread for cond_timedwait to work.
 241
 242       --  It is unclear whether this is True for Solaris threads, FSU threads,
 243       --  both, or maybe just an old version of FSU threads. ????
 244
 245       --  Following signals should not be disturbed. Found by experiment
 246
 247       Keep_Unmasked (SIGEMT) := True;
 248       Keep_Unmasked (SIGCHLD) := True;
 249
 250       --  We do not have Signal 0 in reality. We just use this value
 251       --  to identify not existing signals (see s-intnam.ads). Therefore,
 252       --  Signal 0 should not be used in all signal related operations hence
 253       --  mark it as reserved.
 254
 255       Reserve := Reserve or Keep_Unmasked or Keep_Masked;
 256       Reserve (0) := True;
 257    end;
 258 end System.Interrupt_Management;