gdb/testsuite/gdb.base/sigrepeat.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2004-2021 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <signal.h>
  24 #include <sys/time.h>
  25
  26 static volatile int done[2];
  27 static volatile int repeats[2];
  28 static int itimer[2] = { ITIMER_REAL, ITIMER_VIRTUAL };
  29 static int alarm[2] = { SIGALRM, SIGVTALRM };
  30
  31 static void
  32 handler (int sig)
  33 {
  34   int sigi;
  35   switch (sig)
  36     {
  37     case SIGALRM: sigi = 0; break;
  38     case SIGVTALRM: sigi = 1; break;
  39     default: abort ();
  40     }
  41   if (repeats[sigi]++ > 3)
  42     {
  43       /* Hit with enough signals, cancel everything and get out.  */
  44       {
  45         struct itimerval itime;
  46         memset (&itime, 0, sizeof (itime));
  47         setitimer (itimer[sigi], &itime, NULL);
  48       }
  49       {
  50         struct sigaction action;
  51         memset (&action, 0, sizeof (action));
  52         action.sa_handler = SIG_IGN;
  53         sigaction (sig, &action, NULL);
  54       }
  55       done[sigi] = 1;
  56       return;
  57     }
  58   /* Set up a nested virtual timer.  */
  59   while (1)
  60     {
  61       /* Wait until a signal has become pending, that way when this
  62          handler returns it will be immediatly delivered leading to
  63          back-to-back signals.  */
  64       sigset_t set;
  65       sigemptyset (&set);
  66       if (sigpending (&set) < 0)
  67         {
  68           perror ("sigrepeat");
  69           abort ();
  70         }
  71       if (sigismember (&set, sig))
  72         break;
  73     }
  74 } /* handler */
  75
  76 int
  77 main ()
  78 {
  79   int i;
  80   /* Set up the signal handler.  */
  81   for (i = 0; i < 2; i++)
  82     {
  83       struct sigaction action;
  84       memset (&action, 0, sizeof (action));
  85       action.sa_handler = handler;
  86       sigaction (alarm[i], &action, NULL);
  87     }
  88
  89   /* Set up a rapidly repeating timers.  A timer, rather than SIGSEGV,
  90      is used as after a timer handler returns the interrupted code can
  91      safely resume.  The intent is for the program to swamp GDB with a
  92      backlog of pending signals.  */
  93   for (i = 0; i < 2; i++)
  94     {
  95       struct itimerval itime;
  96       memset (&itime, 0, sizeof (itime));
  97       itime.it_interval.tv_usec = 1;
  98       itime.it_value.tv_usec = 250 * 1000;
  99       setitimer (itimer[i], &itime, NULL);
 100     }
 101
 102   /* Wait.  */
 103   while (!done[0] && !done[1]); /* infinite loop */
 104   return 0;
 105 }