common/signal.c

   1 /* signal.c - signal handling
   2  * Copyright (C) 1998, 1999, 2000, 2001, 2002,
   3  *               2005 Free Software Foundation, Inc.
   4  *
   5  * This file is part of GnuPG.
   6  *
   7  * GnuPG is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 3 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * GnuPG is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <signal.h>
  25 #include <unistd.h>
  26 #include <string.h>
  27 #include <errno.h>
  28 #include <assert.h>
  29
  30 #include "util.h"
  31
  32
  33 #ifndef HAVE_DOSISH_SYSTEM
  34 static volatile int caught_fatal_sig;
  35 static volatile int caught_sigusr1;
  36 #endif
  37 static void (*cleanup_fnc)(void);
  38
  39
  40 #ifndef HAVE_DOSISH_SYSTEM
  41 static void
  42 init_one_signal (int sig, RETSIGTYPE (*handler)(int), int check_ign )
  43 {
  44 # ifdef HAVE_SIGACTION
  45   struct sigaction oact, nact;
  46
  47   if (check_ign)
  48     {
  49       /* we don't want to change an IGN handler */
  50       sigaction (sig, NULL, &oact );
  51       if (oact.sa_handler == SIG_IGN )
  52         return;
  53     }
  54
  55   nact.sa_handler = handler;
  56   sigemptyset (&nact.sa_mask);
  57   nact.sa_flags = 0;
  58   sigaction ( sig, &nact, NULL);
  59 # else
  60   RETSIGTYPE (*ohandler)(int);
  61
  62   ohandler = signal (sig, handler);
  63   if (check_ign && ohandler == SIG_IGN)
  64     {
  65       /* Change it back if it was already set to IGN */
  66       signal (sig, SIG_IGN);
  67     }
  68 # endif
  69 }
  70 #endif /*!HAVE_DOSISH_SYSTEM*/
  71
  72 #ifndef HAVE_DOSISH_SYSTEM
  73 static const char *
  74 get_signal_name( int signum )
  75 {
  76   /* Note that we can't use strsignal(), because it is not
  77      reentrant. */
  78 #if HAVE_DECL_SYS_SIGLIST && defined(NSIG)
  79   return (signum >= 0 && signum < NSIG) ? sys_siglist[signum] : "?";
  80 #else
  81   return NULL;
  82 #endif
  83 }
  84 #endif /*!HAVE_DOSISH_SYSTEM*/
  85
  86 #ifndef HAVE_DOSISH_SYSTEM
  87 static RETSIGTYPE
  88 got_fatal_signal (int sig)
  89 {
  90   const char *s;
  91
  92   if (caught_fatal_sig)
  93     raise (sig);
  94   caught_fatal_sig = 1;
  95
  96   if (cleanup_fnc)
  97     cleanup_fnc ();
  98   /* Better don't translate these messages. */
  99   write (2, "\n", 1 );
 100   s = log_get_prefix (NULL);
 101   if (s)
 102     write(2, s, strlen (s));
 103   write (2, ": signal ", 9 );
 104   s = get_signal_name(sig);
 105   if (s)
 106     write (2, s, strlen(s) );
 107   else
 108     {
 109       /* We are in a signal handler so we can't use any kind of printf
 110          even not sprintf.  So we use a straightforward algorithm.  We
 111          got a report that on one particular system, raising a signal
 112          while in this handler, the parameter SIG get sclobbered and
 113          things are messed up because we modify its value.  Although
 114          this is a bug in that system, we will protect against it.  */
 115       if (sig < 0 || sig >= 100000)
 116         write (2, "?", 1);
 117       else
 118         {
 119           int i, value, any=0;
 120
 121           for (value=sig,i=10000; i; i /= 10)
 122             {
 123               if (value >= i || ((any || i==1) && !(value/i)))
 124                 {
 125                   write (2, "0123456789"+(value/i), 1);
 126                   if ((value/i))
 127                     any = 1;
 128                   value %= i;
 129                 }
 130             }
 131         }
 132     }
 133   write (2, " caught ... exiting\n", 20);
 134
 135   /* Reset action to default action and raise signal again */
 136   init_one_signal (sig, SIG_DFL, 0);
 137   /* Fixme: remove_lockfiles ();*/
 138 #ifdef __riscos__
 139   close_fds ();
 140 #endif /* __riscos__ */
 141   raise( sig );
 142 }
 143 #endif /*!HAVE_DOSISH_SYSTEM*/
 144
 145 #ifndef HAVE_DOSISH_SYSTEM
 146 static RETSIGTYPE
 147 got_usr_signal (int sig)
 148 {
 149   (void)sig;
 150   caught_sigusr1 = 1;
 151 }
 152 #endif /*!HAVE_DOSISH_SYSTEM*/
 153
 154 void
 155 gnupg_init_signals (int mode, void (*fast_cleanup)(void))
 156 {
 157   assert (!mode);
 158
 159   cleanup_fnc = fast_cleanup;
 160 #ifndef HAVE_DOSISH_SYSTEM
 161   init_one_signal (SIGINT, got_fatal_signal, 1 );
 162   init_one_signal (SIGHUP, got_fatal_signal, 1 );
 163   init_one_signal (SIGTERM, got_fatal_signal, 1 );
 164   init_one_signal (SIGQUIT, got_fatal_signal, 1 );
 165   init_one_signal (SIGSEGV, got_fatal_signal, 1 );
 166   init_one_signal (SIGUSR1, got_usr_signal, 0 );
 167   init_one_signal (SIGPIPE, SIG_IGN, 0 );
 168 #endif
 169 }
 170
 171 void
 172 gnupg_pause_on_sigusr (int which)
 173 {
 174 #ifndef HAVE_DOSISH_SYSTEM
 175 # ifdef HAVE_SIGPROCMASK
 176   sigset_t mask, oldmask;
 177
 178   assert (which == 1);
 179   sigemptyset( &mask );
 180   sigaddset( &mask, SIGUSR1 );
 181
 182   sigprocmask( SIG_BLOCK, &mask, &oldmask );
 183   while (!caught_sigusr1)
 184     sigsuspend (&oldmask);
 185   caught_sigusr1 = 0;
 186   sigprocmask (SIG_UNBLOCK, &mask, NULL);
 187 # else
 188   assert (which == 1);
 189   sighold (SIGUSR1);
 190   while (!caught_sigusr1)
 191     sigpause(SIGUSR1);
 192   caught_sigusr1 = 0;
 193   sigrelease(SIGUSR1);
 194 # endif /*!HAVE_SIGPROCMASK*/
 195 #endif
 196 }
 197
 198
 199 static void
 200 do_block( int block )
 201 {
 202 #ifndef HAVE_DOSISH_SYSTEM
 203   static int is_blocked;
 204 #ifdef HAVE_SIGPROCMASK
 205   static sigset_t oldmask;
 206
 207   if (block)
 208     {
 209       sigset_t newmask;
 210
 211       if (is_blocked)
 212         log_bug ("signals are already blocked\n");
 213       sigfillset( &newmask );
 214       sigprocmask( SIG_BLOCK, &newmask, &oldmask );
 215       is_blocked = 1;
 216     }
 217   else
 218     {
 219       if (!is_blocked)
 220         log_bug("signals are not blocked\n");
 221       sigprocmask (SIG_SETMASK, &oldmask, NULL);
 222       is_blocked = 0;
 223     }
 224 #else /*!HAVE_SIGPROCMASK*/
 225   static void (*disposition[MAXSIG])();
 226   int sig;
 227
 228   if (block)
 229     {
 230       if (is_blocked)
 231         log_bug("signals are already blocked\n");
 232       for (sig=1; sig < MAXSIG; sig++)
 233         {
 234           disposition[sig] = sigset (sig, SIG_HOLD);
 235         }
 236       is_blocked = 1;
 237     }
 238   else
 239     {
 240       if (!is_blocked)
 241         log_bug ("signals are not blocked\n");
 242       for (sig=1; sig < MAXSIG; sig++) {
 243         sigset (sig, disposition[sig]);
 244       }
 245       is_blocked = 0;
 246     }
 247 #endif /*!HAVE_SIGPROCMASK*/
 248 #endif /*HAVE_DOSISH_SYSTEM*/
 249 }
 250
 251
 252 void
 253 gnupg_block_all_signals ()
 254 {
 255   do_block(1);
 256 }
 257
 258 void
 259 gnupg_unblock_all_signals ()
 260 {
 261   do_block(0);
 262 }