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 --             Copyright (C) 1991-2002 Florida State University             --
  10 --                                                                          --
  11 -- GNARL 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. GNARL 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 GNARL; 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 -- GNARL was developed by the GNARL team at Florida State University. It is --
  30 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  31 -- State University (http://www.gnat.com).                                  --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is a Sun OS (FSU THREADS) version of this package
  36
  37 --  PLEASE DO NOT add any dependences on other packages. ??? why not ???
  38 --  This package is designed to work with or without tasking support.
  39
  40 --  Make a careful study of all signals available under the OS, to see which
  41 --  need to be reserved, kept always unmasked, or kept always unmasked. Be on
  42 --  the lookout for special signals that may be used by the thread library.
  43
  44 with Interfaces.C;
  45 --  used for int
  46
  47 with System.Error_Reporting;
  48 --  used for Shutdown
  49
  50 with System.OS_Interface;
  51 --  used for various Constants, Signal and types
  52
  53 package body System.Interrupt_Management is
  54
  55    use Interfaces.C;
  56    use System.Error_Reporting;
  57    use System.OS_Interface;
  58
  59    type Interrupt_List is array (Interrupt_ID range <>) of Interrupt_ID;
  60    Exception_Interrupts : constant Interrupt_List :=
  61      (SIGFPE, SIGILL, SIGSEGV);
  62
  63    Unreserve_All_Interrupts : Interfaces.C.int;
  64    pragma Import
  65      (C, Unreserve_All_Interrupts, "__gl_unreserve_all_interrupts");
  66
  67    -----------------------
  68    -- Local Subprograms --
  69    -----------------------
  70
  71    procedure Notify_Exception
  72      (signo   : Signal;
  73       info    : access siginfo_t;
  74       context : access struct_sigcontext);
  75    --  This function identifies the Ada exception to be raised using
  76    --  the information when the system received a synchronous signal.
  77    --  Since this function is machine and OS dependent, different code
  78    --  has to be provided for different target.
  79
  80    ----------------------
  81    -- Notify_Exception --
  82    ----------------------
  83
  84    --  The following code is intended for SunOS on Sparcstation.
  85
  86    procedure Notify_Exception
  87      (signo   : Signal;
  88       info    : access siginfo_t;
  89       context : access struct_sigcontext)
  90    is
  91    begin
  92       --  As long as we are using a longjmp to return control to the
  93       --  exception handler on the runtime stack, we are safe. The original
  94       --  signal mask (the one we had before coming into this signal catching
  95       --  function) will be restored by the longjmp. Therefore, raising
  96       --  an exception in this handler should be a safe operation.
  97
  98       --  Check that treatment of exception propagation here
  99       --  is consistent with treatment of the abort signal in
 100       --  System.Task_Primitives.Operations.
 101
 102       case signo is
 103          when SIGFPE =>
 104             case info.si_code is
 105                when FPE_INTOVF_TRAP   |
 106                     FPE_STARTSIG_TRAP |
 107                     FPE_INTDIV_TRAP   |
 108                     FPE_FLTDIV_TRAP   |
 109                     FPE_FLTUND_TRAP   |
 110                     FPE_FLTOPERR_TRAP |
 111                     FPE_FLTOVF_TRAP =>
 112                   raise Constraint_Error;
 113
 114                when others =>
 115                   pragma Assert (Shutdown ("Unexpected SIGFPE signal"));
 116                   null;
 117             end case;
 118
 119          when SIGILL =>
 120             case info.si_code is
 121                when ILL_STACK           |
 122                     ILL_ILLINSTR_FAULT  |
 123                     ILL_PRIVINSTR_FAULT =>
 124                   raise Constraint_Error;
 125
 126                when others =>
 127                   pragma Assert (Shutdown ("Unexpected SIGILL signal"));
 128                   null;
 129             end case;
 130
 131          when SIGSEGV =>
 132
 133             --  was caused by accessing a null pointer.
 134
 135 --  ???? Origin of this code is unclear, may be broken ???
 136
 137             if context.sc_o0 in 0 .. 16#2000# then
 138                raise Constraint_Error;
 139             else
 140                raise Storage_Error;
 141             end if;
 142
 143          when others =>
 144             pragma Assert (Shutdown ("Unexpected signal"));
 145             null;
 146       end case;
 147    end Notify_Exception;
 148
 149    ---------------------------
 150    -- Initialize_Interrupts --
 151    ---------------------------
 152
 153    --  Nothing needs to be done on this platform
 154
 155    procedure Initialize_Interrupts is
 156    begin
 157       null;
 158    end Initialize_Interrupts;
 159
 160 -------------------------
 161 -- Package Elaboration --
 162 -------------------------
 163
 164 begin
 165    declare
 166       act     : aliased struct_sigaction;
 167       old_act : aliased struct_sigaction;
 168       mask    : aliased sigset_t;
 169       Result  : Interfaces.C.int;
 170
 171    begin
 172       --  Need to call pthread_init very early because it is doing signal
 173       --  initializations.
 174
 175       pthread_init;
 176
 177       --  Change the following assignment to use another signal for task abort.
 178       --  For example, SIGTERM might be a good one if SIGABRT is required for
 179       --  use elsewhere.
 180
 181       Abort_Task_Interrupt := SIGABRT;
 182
 183       act.sa_handler := Notify_Exception'Address;
 184
 185       --  Set sa_flags to SA_NODEFER so that during the handler execution
 186       --  we do not change the Signal_Mask to be masked for the Signal.
 187       --  This is a temporary fix to the problem that the Signal_Mask is
 188       --  not restored after the exception (longjmp) from the handler.
 189       --  The right fix should be made in sigsetjmp so that we save
 190       --  the Signal_Set and restore it after a longjmp.
 191
 192       --  In that case, this field should be changed back to 0. ???
 193
 194       act.sa_flags := 16;
 195
 196       Result := sigemptyset (mask'Access);
 197       pragma Assert (Result = 0);
 198
 199       for J in Exception_Interrupts'Range loop
 200          Result := sigaddset (mask'Access, Signal (Exception_Interrupts (J)));
 201          pragma Assert (Result = 0);
 202       end loop;
 203
 204       act.sa_mask := mask;
 205
 206       for J in Exception_Interrupts'Range loop
 207          Keep_Unmasked (Exception_Interrupts (J)) := True;
 208
 209          Result :=
 210            sigaction
 211            (Signal (Exception_Interrupts (J)),
 212             act'Unchecked_Access,
 213             old_act'Unchecked_Access);
 214          pragma Assert (Result = 0);
 215       end loop;
 216
 217       Keep_Unmasked (Abort_Task_Interrupt) := True;
 218       Keep_Unmasked (SIGALRM) := True;
 219       Keep_Unmasked (SIGSTOP) := True;
 220       Keep_Unmasked (SIGKILL) := True;
 221
 222       --  By keeping SIGINT unmasked, allow the user to do a Ctrl-C, but at
 223       --  the same time, disable the ability of handling this signal using
 224       --  package Ada.Interrupts.
 225
 226       --  The pragma Unreserve_All_Interrupts allows the user the ability to
 227       --  change this behavior.
 228
 229       if Unreserve_All_Interrupts = 0 then
 230          Keep_Unmasked (SIGINT) := True;
 231       end if;
 232
 233       --  Reserve this not to interfere with thread scheduling
 234
 235       --  ??? consider adding this to interrupt exceptions
 236       --  Keep_Unmasked (SIGALRM) := True;
 237
 238       --  An earlier version had a comment about SIGALRM needing to be unmasked
 239       --  in at least one thread for cond_timedwait to work.
 240
 241       --  It is unclear whether this is True for Solaris threads, FSU threads,
 242       --  both, or maybe just an old version of FSU threads. ????
 243
 244       --  Following signals should not be disturbed. Found by experiment
 245
 246       Keep_Unmasked (SIGEMT) := True;
 247       Keep_Unmasked (SIGCHLD) := True;
 248
 249       --  We do not have Signal 0 in reality. We just use this value
 250       --  to identify not existing signals (see s-intnam.ads). Therefore,
 251       --  Signal 0 should not be used in all signal related operations hence
 252       --  mark it as reserved.
 253
 254       Reserve := Reserve or Keep_Unmasked or Keep_Masked;
 255       Reserve (0) := True;
 256    end;
 257 end System.Interrupt_Management;