lib/sigevent.c

   1 /* Quagga signal handling functions.
   2  * Copyright (C) 2004 Paul Jakma,
   3  *
   4  * This file is part of Quagga.
   5  *
   6  * Quagga is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * Quagga is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with Quagga; see the file COPYING.  If not, write to the Free
  18  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  19  * 02111-1307, USA.
  20  */
  21
  22 #include <zebra.h>
  23 #include <sigevent.h>
  24 #include <log.h>
  25 #include <memory.h>
  26
  27 #ifdef SA_SIGINFO
  28 #ifdef HAVE_UCONTEXT_H
  29 #ifdef GNU_LINUX
  30 /* get REG_EIP from ucontext.h */
  31 #ifndef __USE_GNU
  32 #define __USE_GNU
  33 #endif /* __USE_GNU */
  34 #endif /* GNU_LINUX */
  35 #include <ucontext.h>
  36 #endif /* HAVE_UCONTEXT_H */
  37 #endif /* SA_SIGINFO */
  38
  39
  40 /* master signals descriptor struct */
  41 struct quagga_sigevent_master_t
  42 {
  43   struct thread *t;
  44
  45   struct quagga_signal_t *signals;
  46   int sigc;
  47
  48   volatile sig_atomic_t caught;
  49 } sigmaster;
  50
  51 /* Generic signal handler
  52  * Schedules signal event thread
  53  */
  54 static void
  55 quagga_signal_handler (int signo)
  56 {
  57   int i;
  58   struct quagga_signal_t *sig;
  59
  60   for (i = 0; i < sigmaster.sigc; i++)
  61     {
  62       sig = &(sigmaster.signals[i]);
  63
  64       if (sig->signal == signo)
  65         sig->caught = 1;
  66     }
  67
  68   sigmaster.caught = 1;
  69 }
  70
  71 /* check if signals have been caught and run appropriate handlers */
  72 int
  73 quagga_sigevent_process (void)
  74 {
  75   struct quagga_signal_t *sig;
  76   int i;
  77 #ifdef SIGEVENT_BLOCK_SIGNALS
  78   /* shouldnt need to block signals, but potentially may be needed */
  79   sigset_t newmask, oldmask;
  80
  81   /*
  82    * Block most signals, but be careful not to defer SIGTRAP because
  83    * doing so breaks gdb, at least on NetBSD 2.0.  Avoid asking to
  84    * block SIGKILL, just because we shouldn't be able to do so.
  85    */
  86   sigfillset (&newmask);
  87   sigdelset (&newmask, SIGTRAP);
  88   sigdelset (&newmask, SIGKILL);
  89
  90   if ( (sigprocmask (SIG_BLOCK, &newmask, &oldmask)) < 0)
  91     {
  92       zlog_err ("quagga_signal_timer: couldnt block signals!");
  93       return -1;
  94     }
  95 #endif /* SIGEVENT_BLOCK_SIGNALS */
  96
  97   if (sigmaster.caught > 0)
  98     {
  99       sigmaster.caught = 0;
 100       /* must not read or set sigmaster.caught after here,
 101        * race condition with per-sig caught flags if one does
 102        */
 103
 104       for (i = 0; i < sigmaster.sigc; i++)
 105         {
 106           sig = &(sigmaster.signals[i]);
 107
 108           if (sig->caught > 0)
 109             {
 110               sig->caught = 0;
 111               sig->handler ();
 112             }
 113         }
 114     }
 115
 116 #ifdef SIGEVENT_BLOCK_SIGNALS
 117   if ( sigprocmask (SIG_UNBLOCK, &oldmask, NULL) < 0 );
 118     return -1;
 119 #endif /* SIGEVENT_BLOCK_SIGNALS */
 120
 121   return 0;
 122 }
 123
 124 #ifdef SIGEVENT_SCHEDULE_THREAD
 125 /* timer thread to check signals. Shouldnt be needed */
 126 int
 127 quagga_signal_timer (struct thread *t)
 128 {
 129   struct quagga_sigevent_master_t *sigm;
 130   struct quagga_signal_t *sig;
 131   int i;
 132
 133   sigm = THREAD_ARG (t);
 134   sigm->t = thread_add_timer (sigm->t->master, quagga_signal_timer, &sigmaster,
 135                               QUAGGA_SIGNAL_TIMER_INTERVAL);
 136   return quagga_sigevent_process ();
 137 }
 138 #endif /* SIGEVENT_SCHEDULE_THREAD */
 139
 140 /* Initialization of signal handles. */
 141 /* Signal wrapper. */
 142 static int
 143 signal_set (int signo)
 144 {
 145   int ret;
 146   struct sigaction sig;
 147   struct sigaction osig;
 148
 149   sig.sa_handler = &quagga_signal_handler;
 150   sigfillset (&sig.sa_mask);
 151   sig.sa_flags = 0;
 152   if (signo == SIGALRM) {
 153 #ifdef SA_INTERRUPT
 154       sig.sa_flags |= SA_INTERRUPT; /* SunOS */
 155 #endif
 156   } else {
 157 #ifdef SA_RESTART
 158       sig.sa_flags |= SA_RESTART;
 159 #endif /* SA_RESTART */
 160   }
 161
 162   ret = sigaction (signo, &sig, &osig);
 163   if (ret < 0)
 164     return ret;
 165   else
 166     return 0;
 167 }
 168
 169 #ifdef SA_SIGINFO
 170
 171 /* XXX This function should be enhanced to support more platforms
 172        (it currently works only on Linux/x86). */
 173 static void *
 174 program_counter(void *context)
 175 {
 176 #ifdef HAVE_UCONTEXT_H
 177 #ifdef GNU_LINUX
 178   /* these are from GNU libc, rather than Linux, strictly speaking */
 179 # if defined(REG_EIP)
 180 #  define REG_INDEX REG_EIP
 181 # elif defined(REG_RIP)
 182 #  define REG_INDEX REG_RIP
 183 # elif defined(__powerpc__)
 184 #  define REG_INDEX 32
 185 # endif
 186 #elif defined(SUNOS_5) /* !GNU_LINUX */
 187 # define REG_INDEX REG_PC
 188 #endif /* GNU_LINUX */
 189
 190 #ifdef REG_INDEX
 191 # ifdef HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS
 192 #  define REGS gregs[REG_INDEX]
 193 # elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_UC_REGS)
 194 #  define REGS uc_regs->gregs[REG_INDEX]
 195 # endif /* HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS */
 196 #endif /* REG_INDEX */
 197
 198 #ifdef REGS
 199   if (context)
 200     return (void *)(((ucontext_t *)context)->uc_mcontext.REGS);
 201 #elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_REGS__NIP)
 202   /* older Linux / struct pt_regs ? */
 203   if (context)
 204     return (void *)(((ucontext_t *)context)->uc_mcontext.regs->nip);
 205 #endif /* REGS */
 206
 207 #endif /* HAVE_UCONTEXT_H */
 208   return NULL;
 209 }
 210
 211 #endif /* SA_SIGINFO */
 212
 213 static void __attribute__ ((noreturn))
 214 exit_handler(int signo
 215 #ifdef SA_SIGINFO
 216              , siginfo_t *siginfo, void *context
 217 #endif
 218             )
 219 {
 220   zlog_signal(signo, "exiting..."
 221 #ifdef SA_SIGINFO
 222               , siginfo, program_counter(context)
 223 #endif
 224              );
 225   _exit(128+signo);
 226 }
 227
 228 static void __attribute__ ((noreturn))
 229 core_handler(int signo
 230 #ifdef SA_SIGINFO
 231              , siginfo_t *siginfo, void *context
 232 #endif
 233             )
 234 {
 235   zlog_signal(signo, "aborting..."
 236 #ifdef SA_SIGINFO
 237               , siginfo, program_counter(context)
 238 #endif
 239              );
 240   /* dump memory stats on core */
 241   log_memstats_stderr ("core_handler");
 242   abort();
 243 }
 244
 245 static void
 246 trap_default_signals(void)
 247 {
 248   static const int core_signals[] = {
 249     SIGQUIT,
 250     SIGILL,
 251 #ifdef SIGEMT
 252     SIGEMT,
 253 #endif
 254     SIGFPE,
 255     SIGBUS,
 256     SIGSEGV,
 257 #ifdef SIGSYS
 258     SIGSYS,
 259 #endif
 260 #ifdef SIGXCPU
 261     SIGXCPU,
 262 #endif
 263 #ifdef SIGXFSZ
 264     SIGXFSZ,
 265 #endif
 266   };
 267   static const int exit_signals[] = {
 268     SIGHUP,
 269     SIGINT,
 270     SIGALRM,
 271     SIGTERM,
 272     SIGUSR1,
 273     SIGUSR2,
 274 #ifdef SIGPOLL
 275     SIGPOLL,
 276 #endif
 277 #ifdef SIGVTALRM
 278     SIGVTALRM,
 279 #endif
 280 #ifdef SIGSTKFLT
 281     SIGSTKFLT,
 282 #endif
 283   };
 284   static const int ignore_signals[] = {
 285     SIGPIPE,
 286   };
 287   static const struct {
 288     const int *sigs;
 289     u_int nsigs;
 290     void (*handler)(int signo
 291 #ifdef SA_SIGINFO
 292                     , siginfo_t *info, void *context
 293 #endif
 294                    );
 295   } sigmap[] = {
 296     { core_signals, array_size(core_signals), core_handler},
 297     { exit_signals, array_size(exit_signals), exit_handler},
 298     { ignore_signals, array_size(ignore_signals), NULL},
 299   };
 300   u_int i;
 301
 302   for (i = 0; i < array_size(sigmap); i++)
 303     {
 304       u_int j;
 305
 306       for (j = 0; j < sigmap[i].nsigs; j++)
 307         {
 308           struct sigaction oact;
 309           if ((sigaction(sigmap[i].sigs[j],NULL,&oact) == 0) &&
 310               (oact.sa_handler == SIG_DFL))
 311             {
 312               struct sigaction act;
 313               sigfillset (&act.sa_mask);
 314               if (sigmap[i].handler == NULL)
 315                 {
 316                   act.sa_handler = SIG_IGN;
 317                   act.sa_flags = 0;
 318                 }
 319               else
 320                 {
 321 #ifdef SA_SIGINFO
 322                   /* Request extra arguments to signal handler. */
 323                   act.sa_sigaction = sigmap[i].handler;
 324                   act.sa_flags = SA_SIGINFO;
 325 #else
 326                   act.sa_handler = sigmap[i].handler;
 327                   act.sa_flags = 0;
 328 #endif
 329                 }
 330               if (sigaction(sigmap[i].sigs[j],&act,NULL) < 0)
 331                 zlog_warn("Unable to set signal handler for signal %d: %s",
 332                           sigmap[i].sigs[j],safe_strerror(errno));
 333
 334             }
 335         }
 336     }
 337 }
 338
 339 void
 340 signal_init (struct thread_master *m, int sigc,
 341              struct quagga_signal_t signals[])
 342 {
 343
 344   int i = 0;
 345   struct quagga_signal_t *sig;
 346
 347   /* First establish some default handlers that can be overridden by
 348      the application. */
 349   trap_default_signals();
 350
 351   while (i < sigc)
 352     {
 353       sig = &signals[i];
 354       if ( signal_set (sig->signal) < 0 )
 355         exit (-1);
 356       i++;
 357     }
 358
 359   sigmaster.sigc = sigc;
 360   sigmaster.signals = signals;
 361
 362 #ifdef SIGEVENT_SCHEDULE_THREAD
 363   sigmaster.t =
 364     thread_add_timer (m, quagga_signal_timer, &sigmaster,
 365                       QUAGGA_SIGNAL_TIMER_INTERVAL);
 366 #endif /* SIGEVENT_SCHEDULE_THREAD */
 367 }