lib/sigevent.c - quagga - Gitiles

 /* Quagga signal handling functions.
  * Copyright (C) 2004 Paul Jakma,
  *
  * This file is part of Quagga.
  *
  * Quagga is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
  * Free Software Foundation; either version 2, or (at your option) any
  * later version.
  *
  * Quagga is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Quagga; see the file COPYING.  If not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  * 02111-1307, USA.
  */

 #include <zebra.h>
 #include <sigevent.h>
 #include <log.h>
 #include <memory.h>

 #ifdef SA_SIGINFO
 #ifdef HAVE_UCONTEXT_H
 #ifdef GNU_LINUX
 /* get REG_EIP from ucontext.h */
 #ifndef __USE_GNU
 #define __USE_GNU
 #endif /* __USE_GNU */
 #endif /* GNU_LINUX */
 #include <ucontext.h>
 #endif /* HAVE_UCONTEXT_H */
 #endif /* SA_SIGINFO */


 /* master signals descriptor struct */
 struct quagga_sigevent_master_t
 {
   struct thread *t;

   struct quagga_signal_t *signals;
   int sigc;

   volatile sig_atomic_t caught;
 } sigmaster;

 /* Generic signal handler
  * Schedules signal event thread
  */
 static void
 quagga_signal_handler (int signo)
 {
   int i;
   struct quagga_signal_t *sig;

   for (i = 0; i < sigmaster.sigc; i++)
     {
       sig = &(sigmaster.signals[i]);

       if (sig->signal == signo)
         sig->caught = 1;
     }

   sigmaster.caught = 1;
 }

 /* check if signals have been caught and run appropriate handlers */
 int
 quagga_sigevent_process (void)
 {
   struct quagga_signal_t *sig;
   int i;
 #ifdef SIGEVENT_BLOCK_SIGNALS
   /* shouldnt need to block signals, but potentially may be needed */
   sigset_t newmask, oldmask;

   /*
    * Block most signals, but be careful not to defer SIGTRAP because
    * doing so breaks gdb, at least on NetBSD 2.0.  Avoid asking to
    * block SIGKILL, just because we shouldn't be able to do so.
    */
   sigfillset (&newmask);
   sigdelset (&newmask, SIGTRAP);
   sigdelset (&newmask, SIGKILL);

   if ( (sigprocmask (SIG_BLOCK, &newmask, &oldmask)) < 0)
     {
       zlog_err ("quagga_signal_timer: couldnt block signals!");
       return -1;
     }
 #endif /* SIGEVENT_BLOCK_SIGNALS */

   if (sigmaster.caught > 0)
     {
       sigmaster.caught = 0;
       /* must not read or set sigmaster.caught after here,
        * race condition with per-sig caught flags if one does
        */

       for (i = 0; i < sigmaster.sigc; i++)
         {
           sig = &(sigmaster.signals[i]);

           if (sig->caught > 0)
             {
               sig->caught = 0;
               sig->handler ();
             }
         }
     }

 #ifdef SIGEVENT_BLOCK_SIGNALS
   if ( sigprocmask (SIG_UNBLOCK, &oldmask, NULL) < 0 );
     return -1;
 #endif /* SIGEVENT_BLOCK_SIGNALS */

   return 0;
 }

 #ifdef SIGEVENT_SCHEDULE_THREAD
 /* timer thread to check signals. Shouldnt be needed */
 int
 quagga_signal_timer (struct thread *t)
 {
   struct quagga_sigevent_master_t *sigm;
   struct quagga_signal_t *sig;
   int i;

   sigm = THREAD_ARG (t);
   sigm->t = thread_add_timer (sigm->t->master, quagga_signal_timer, &sigmaster,
                               QUAGGA_SIGNAL_TIMER_INTERVAL);
   return quagga_sigevent_process ();
 }
 #endif /* SIGEVENT_SCHEDULE_THREAD */

 /* Initialization of signal handles. */
 /* Signal wrapper. */
 static int
 signal_set (int signo)
 {
   int ret;
   struct sigaction sig;
   struct sigaction osig;

   sig.sa_handler = &quagga_signal_handler;
   sigfillset (&sig.sa_mask);
   sig.sa_flags = 0;
   if (signo == SIGALRM) {
 #ifdef SA_INTERRUPT
       sig.sa_flags |= SA_INTERRUPT; /* SunOS */
 #endif
   } else {
 #ifdef SA_RESTART
       sig.sa_flags |= SA_RESTART;
 #endif /* SA_RESTART */
   }

   ret = sigaction (signo, &sig, &osig);
   if (ret < 0)
     return ret;
   else
     return 0;
 }

 #ifdef SA_SIGINFO

 /* XXX This function should be enhanced to support more platforms
        (it currently works only on Linux/x86). */
 static void *
 program_counter(void *context)
 {
 #ifdef HAVE_UCONTEXT_H
 #ifdef GNU_LINUX
   /* these are from GNU libc, rather than Linux, strictly speaking */
 # if defined(REG_EIP)
 #  define REG_INDEX REG_EIP
 # elif defined(REG_RIP)
 #  define REG_INDEX REG_RIP
 # elif defined(__powerpc__)
 #  define REG_INDEX 32
 # endif
 #elif defined(SUNOS_5) /* !GNU_LINUX */
 # define REG_INDEX REG_PC
 #endif /* GNU_LINUX */

 #ifdef REG_INDEX
 # ifdef HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS
 #  define REGS gregs[REG_INDEX]
 # elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_UC_REGS)
 #  define REGS uc_regs->gregs[REG_INDEX]
 # endif /* HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS */
 #endif /* REG_INDEX */

 #ifdef REGS
   if (context)
     return (void *)(((ucontext_t *)context)->uc_mcontext.REGS);
 #elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_REGS__NIP)
   /* older Linux / struct pt_regs ? */
   if (context)
     return (void *)(((ucontext_t *)context)->uc_mcontext.regs->nip);
 #endif /* REGS */

 #endif /* HAVE_UCONTEXT_H */
   return NULL;
 }

 #endif /* SA_SIGINFO */

 static void __attribute__ ((noreturn))
 exit_handler(int signo
 #ifdef SA_SIGINFO
 	     , siginfo_t *siginfo, void *context
 #endif
 	    )
 {
   zlog_signal(signo, "exiting..."
 #ifdef SA_SIGINFO
 	      , siginfo, program_counter(context)
 #endif
 	     );
   _exit(128+signo);
 }

 static void __attribute__ ((noreturn))
 core_handler(int signo
 #ifdef SA_SIGINFO
 	     , siginfo_t *siginfo, void *context
 #endif
 	    )
 {
   zlog_signal(signo, "aborting..."
 #ifdef SA_SIGINFO
 	      , siginfo, program_counter(context)
 #endif
 	     );
   /* dump memory stats on core */
   log_memstats_stderr ("core_handler");
   abort();
 }

 static void
 trap_default_signals(void)
 {
   static const int core_signals[] = {
     SIGQUIT,
     SIGILL,
 #ifdef SIGEMT
     SIGEMT,
 #endif
     SIGFPE,
     SIGBUS,
     SIGSEGV,
 #ifdef SIGSYS
     SIGSYS,
 #endif
 #ifdef SIGXCPU
     SIGXCPU,
 #endif
 #ifdef SIGXFSZ
     SIGXFSZ,
 #endif
   };
   static const int exit_signals[] = {
     SIGHUP,
     SIGINT,
     SIGALRM,
     SIGTERM,
     SIGUSR1,
     SIGUSR2,
 #ifdef SIGPOLL
     SIGPOLL,
 #endif
 #ifdef SIGVTALRM
     SIGVTALRM,
 #endif
 #ifdef SIGSTKFLT
     SIGSTKFLT,
 #endif
   };
   static const int ignore_signals[] = {
     SIGPIPE,
   };
   static const struct {
     const int *sigs;
     u_int nsigs;
     void (*handler)(int signo
 #ifdef SA_SIGINFO
 		    , siginfo_t *info, void *context
 #endif
 		   );
   } sigmap[] = {
     { core_signals, array_size(core_signals), core_handler},
     { exit_signals, array_size(exit_signals), exit_handler},
     { ignore_signals, array_size(ignore_signals), NULL},
   };
   u_int i;

   for (i = 0; i < array_size(sigmap); i++)
     {
       u_int j;

       for (j = 0; j < sigmap[i].nsigs; j++)
         {
 	  struct sigaction oact;
 	  if ((sigaction(sigmap[i].sigs[j],NULL,&oact) == 0) &&
 	      (oact.sa_handler == SIG_DFL))
 	    {
 	      struct sigaction act;
 	      sigfillset (&act.sa_mask);
 	      if (sigmap[i].handler == NULL)
 	        {
 		  act.sa_handler = SIG_IGN;
 		  act.sa_flags = 0;
 	        }
 	      else
 	        {
 #ifdef SA_SIGINFO
 		  /* Request extra arguments to signal handler. */
 		  act.sa_sigaction = sigmap[i].handler;
 		  act.sa_flags = SA_SIGINFO;
 #else
 		  act.sa_handler = sigmap[i].handler;
 		  act.sa_flags = 0;
 #endif
 	        }
 	      if (sigaction(sigmap[i].sigs[j],&act,NULL) < 0)
 	        zlog_warn("Unable to set signal handler for signal %d: %s",
 			  sigmap[i].sigs[j],safe_strerror(errno));

 	    }
         }
     }
 }

 void
 signal_init (struct thread_master *m, int sigc,
              struct quagga_signal_t signals[])
 {

   int i = 0;
   struct quagga_signal_t *sig;

   /* First establish some default handlers that can be overridden by
      the application. */
   trap_default_signals();

   while (i < sigc)
     {
       sig = &signals[i];
       if ( signal_set (sig->signal) < 0 )
         exit (-1);
       i++;
     }

   sigmaster.sigc = sigc;
   sigmaster.signals = signals;

 #ifdef SIGEVENT_SCHEDULE_THREAD
   sigmaster.t =
     thread_add_timer (m, quagga_signal_timer, &sigmaster,
                       QUAGGA_SIGNAL_TIMER_INTERVAL);
 #endif /* SIGEVENT_SCHEDULE_THREAD */
 }
	/* Quagga signal handling functions.
	* Copyright (C) 2004 Paul Jakma,
	*
	* This file is part of Quagga.
	*
	* Quagga is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the
	* Free Software Foundation; either version 2, or (at your option) any
	* later version.
	*
	* Quagga is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with Quagga; see the file COPYING. If not, write to the Free
	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	* 02111-1307, USA.
	*/

	#include <zebra.h>
	#include <sigevent.h>
	#include <log.h>
	#include <memory.h>

	#ifdef SA_SIGINFO
	#ifdef HAVE_UCONTEXT_H
	#ifdef GNU_LINUX
	/* get REG_EIP from ucontext.h */
	#ifndef __USE_GNU
	#define __USE_GNU
	#endif /* __USE_GNU */
	#endif /* GNU_LINUX */
	#include <ucontext.h>
	#endif /* HAVE_UCONTEXT_H */
	#endif /* SA_SIGINFO */


	/* master signals descriptor struct */
	struct quagga_sigevent_master_t
	{
	struct thread *t;

	struct quagga_signal_t *signals;
	int sigc;

	volatile sig_atomic_t caught;
	} sigmaster;

	/* Generic signal handler
	* Schedules signal event thread
	*/
	static void
	quagga_signal_handler (int signo)
	{
	int i;
	struct quagga_signal_t *sig;

	for (i = 0; i < sigmaster.sigc; i++)
	{
	sig = &(sigmaster.signals[i]);

	if (sig->signal == signo)
	sig->caught = 1;
	}

	sigmaster.caught = 1;
	}

	/* check if signals have been caught and run appropriate handlers */
	int
	quagga_sigevent_process (void)
	{
	struct quagga_signal_t *sig;
	int i;
	#ifdef SIGEVENT_BLOCK_SIGNALS
	/* shouldnt need to block signals, but potentially may be needed */
	sigset_t newmask, oldmask;

	/*
	* Block most signals, but be careful not to defer SIGTRAP because
	* doing so breaks gdb, at least on NetBSD 2.0. Avoid asking to
	* block SIGKILL, just because we shouldn't be able to do so.
	*/
	sigfillset (&newmask);
	sigdelset (&newmask, SIGTRAP);
	sigdelset (&newmask, SIGKILL);

	if ( (sigprocmask (SIG_BLOCK, &newmask, &oldmask)) < 0)
	{
	zlog_err ("quagga_signal_timer: couldnt block signals!");
	return -1;
	}
	#endif /* SIGEVENT_BLOCK_SIGNALS */

	if (sigmaster.caught > 0)
	{
	sigmaster.caught = 0;
	/* must not read or set sigmaster.caught after here,
	* race condition with per-sig caught flags if one does
	*/

	for (i = 0; i < sigmaster.sigc; i++)
	{
	sig = &(sigmaster.signals[i]);

	if (sig->caught > 0)
	{
	sig->caught = 0;
	sig->handler ();
	}
	}
	}

	#ifdef SIGEVENT_BLOCK_SIGNALS
	if ( sigprocmask (SIG_UNBLOCK, &oldmask, NULL) < 0 );
	return -1;
	#endif /* SIGEVENT_BLOCK_SIGNALS */

	return 0;
	}

	#ifdef SIGEVENT_SCHEDULE_THREAD
	/* timer thread to check signals. Shouldnt be needed */
	int
	quagga_signal_timer (struct thread *t)
	{
	struct quagga_sigevent_master_t *sigm;
	struct quagga_signal_t *sig;
	int i;

	sigm = THREAD_ARG (t);
	sigm->t = thread_add_timer (sigm->t->master, quagga_signal_timer, &sigmaster,
	QUAGGA_SIGNAL_TIMER_INTERVAL);
	return quagga_sigevent_process ();
	}
	#endif /* SIGEVENT_SCHEDULE_THREAD */

	/* Initialization of signal handles. */
	/* Signal wrapper. */
	static int
	signal_set (int signo)
	{
	int ret;
	struct sigaction sig;
	struct sigaction osig;

	sig.sa_handler = &quagga_signal_handler;
	sigfillset (&sig.sa_mask);
	sig.sa_flags = 0;
	if (signo == SIGALRM) {
	#ifdef SA_INTERRUPT
	sig.sa_flags \|= SA_INTERRUPT; /* SunOS */
	#endif
	} else {
	#ifdef SA_RESTART
	sig.sa_flags \|= SA_RESTART;
	#endif /* SA_RESTART */
	}

	ret = sigaction (signo, &sig, &osig);
	if (ret < 0)
	return ret;
	else
	return 0;
	}

	#ifdef SA_SIGINFO

	/* XXX This function should be enhanced to support more platforms
	(it currently works only on Linux/x86). */
	static void *
	program_counter(void *context)
	{
	#ifdef HAVE_UCONTEXT_H
	#ifdef GNU_LINUX
	/* these are from GNU libc, rather than Linux, strictly speaking */
	# if defined(REG_EIP)
	# define REG_INDEX REG_EIP
	# elif defined(REG_RIP)
	# define REG_INDEX REG_RIP
	# elif defined(__powerpc__)
	# define REG_INDEX 32
	# endif
	#elif defined(SUNOS_5) /* !GNU_LINUX */
	# define REG_INDEX REG_PC
	#endif /* GNU_LINUX */

	#ifdef REG_INDEX
	# ifdef HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS
	# define REGS gregs[REG_INDEX]
	# elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_UC_REGS)
	# define REGS uc_regs->gregs[REG_INDEX]
	# endif /* HAVE_UCONTEXT_T_UC_MCONTEXT_GREGS */
	#endif /* REG_INDEX */

	#ifdef REGS
	if (context)
	return (void )(((ucontext_t )context)->uc_mcontext.REGS);
	#elif defined(HAVE_UCONTEXT_T_UC_MCONTEXT_REGS__NIP)
	/* older Linux / struct pt_regs ? */
	if (context)
	return (void )(((ucontext_t )context)->uc_mcontext.regs->nip);
	#endif /* REGS */

	#endif /* HAVE_UCONTEXT_H */
	return NULL;
	}

	#endif /* SA_SIGINFO */

	static void __attribute__ ((noreturn))
	exit_handler(int signo
	#ifdef SA_SIGINFO
	, siginfo_t siginfo, void context
	#endif
	)
	{
	zlog_signal(signo, "exiting..."
	#ifdef SA_SIGINFO
	, siginfo, program_counter(context)
	#endif
	);
	_exit(128+signo);
	}

	static void __attribute__ ((noreturn))
	core_handler(int signo
	#ifdef SA_SIGINFO
	, siginfo_t siginfo, void context
	#endif
	)
	{
	zlog_signal(signo, "aborting..."
	#ifdef SA_SIGINFO
	, siginfo, program_counter(context)
	#endif
	);
	/* dump memory stats on core */
	log_memstats_stderr ("core_handler");
	abort();
	}

	static void
	trap_default_signals(void)
	{
	static const int core_signals[] = {
	SIGQUIT,
	SIGILL,
	#ifdef SIGEMT
	SIGEMT,
	#endif
	SIGFPE,
	SIGBUS,
	SIGSEGV,
	#ifdef SIGSYS
	SIGSYS,
	#endif
	#ifdef SIGXCPU
	SIGXCPU,
	#endif
	#ifdef SIGXFSZ
	SIGXFSZ,
	#endif
	};
	static const int exit_signals[] = {
	SIGHUP,
	SIGINT,
	SIGALRM,
	SIGTERM,
	SIGUSR1,
	SIGUSR2,
	#ifdef SIGPOLL
	SIGPOLL,
	#endif
	#ifdef SIGVTALRM
	SIGVTALRM,
	#endif
	#ifdef SIGSTKFLT
	SIGSTKFLT,
	#endif
	};
	static const int ignore_signals[] = {
	SIGPIPE,
	};
	static const struct {
	const int *sigs;
	u_int nsigs;
	void (*handler)(int signo
	#ifdef SA_SIGINFO
	, siginfo_t info, void context
	#endif
	);
	} sigmap[] = {
	{ core_signals, array_size(core_signals), core_handler},
	{ exit_signals, array_size(exit_signals), exit_handler},
	{ ignore_signals, array_size(ignore_signals), NULL},
	};
	u_int i;

	for (i = 0; i < array_size(sigmap); i++)
	{
	u_int j;

	for (j = 0; j < sigmap[i].nsigs; j++)
	{
	struct sigaction oact;
	if ((sigaction(sigmap[i].sigs[j],NULL,&oact) == 0) &&
	(oact.sa_handler == SIG_DFL))
	{
	struct sigaction act;
	sigfillset (&act.sa_mask);
	if (sigmap[i].handler == NULL)
	{
	act.sa_handler = SIG_IGN;
	act.sa_flags = 0;
	}
	else
	{
	#ifdef SA_SIGINFO
	/* Request extra arguments to signal handler. */
	act.sa_sigaction = sigmap[i].handler;
	act.sa_flags = SA_SIGINFO;
	#else
	act.sa_handler = sigmap[i].handler;
	act.sa_flags = 0;
	#endif
	}
	if (sigaction(sigmap[i].sigs[j],&act,NULL) < 0)
	zlog_warn("Unable to set signal handler for signal %d: %s",
	sigmap[i].sigs[j],safe_strerror(errno));

	}
	}
	}
	}

	void
	signal_init (struct thread_master *m, int sigc,
	struct quagga_signal_t signals[])
	{

	int i = 0;
	struct quagga_signal_t *sig;

	/* First establish some default handlers that can be overridden by
	the application. */
	trap_default_signals();

	while (i < sigc)
	{
	sig = &signals[i];
	if ( signal_set (sig->signal) < 0 )
	exit (-1);
	i++;
	}

	sigmaster.sigc = sigc;
	sigmaster.signals = signals;

	#ifdef SIGEVENT_SCHEDULE_THREAD
	sigmaster.t =
	thread_add_timer (m, quagga_signal_timer, &sigmaster,
	QUAGGA_SIGNAL_TIMER_INTERVAL);
	#endif /* SIGEVENT_SCHEDULE_THREAD */
	}