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sigaltstack.c revision 1.6.4.1 
      1 /* This testcase is part of GDB, the GNU debugger.
      2 
      3    Copyright 2004-2017 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 #include <signal.h>
     19 #include <stdio.h>
     20 #include <stdlib.h>
     21 #include <string.h>
     22 #include <sys/time.h>
     23 
     24 enum level { MAIN, OUTER, INNER, LEAF, NR_LEVELS };
     25 
     26 /* Levels completed flag.  */
     27 volatile enum level level = NR_LEVELS;
     28 
     29 void catcher (int signal);
     30 
     31 void
     32 thrower (enum level next_level, int sig, int itimer, int on_stack)
     33 {
     34   level = next_level;
     35   /* Set up the signal handler.  */
     36   {
     37     struct sigaction act;
     38     memset (&act, 0, sizeof (act));
     39     act.sa_handler = catcher;
     40     act.sa_flags |= on_stack;
     41     sigaction (sig, &act, NULL);
     42   }
     43   /* Set up a one-off timer.  A timer, rather than SIGSEGV, is used as
     44      after a timer handler finishes the interrupted code can safely
     45      resume.  */
     46   {
     47     struct itimerval itime;
     48     memset (&itime, 0, sizeof (itime));
     49     itime.it_value.tv_usec = 250 * 1000;
     50     setitimer (itimer, &itime, NULL);
     51   }
     52   /* Wait.  */
     53   while (level != LEAF);
     54 }
     55 
     56 void
     57 catcher (int signal)
     58 {
     59   /* Find the next level.  */
     60   switch (level)
     61     {
     62     case MAIN:
     63       thrower (OUTER, SIGALRM, ITIMER_REAL, SA_ONSTACK);
     64       break;
     65     case OUTER:
     66       thrower (INNER, SIGVTALRM, ITIMER_VIRTUAL, SA_ONSTACK);
     67       break;
     68     case INNER:
     69       level = LEAF;
     70       return;
     71     }
     72 }
     73 
     74 
     75 int
     76 main ()
     77 {
     78   /* Set up the altstack.  */
     79   {
     80     static char stack[SIGSTKSZ * NR_LEVELS];
     81     stack_t alt;
     82     memset (&alt, 0, sizeof (alt));
     83     alt.ss_sp = stack;
     84     alt.ss_size = SIGSTKSZ;
     85     alt.ss_flags = 0;
     86     if (sigaltstack (&alt, NULL) < 0)
     87       {
     88 	perror ("sigaltstack");
     89 	exit (0);
     90       }
     91   }
     92   level = MAIN;
     93   catcher (0);
     94   return 0;
     95 }
     96