1 /* This testcase is part of GDB, the GNU debugger.
2 
3    Copyright 2004 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 2 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, write to the Free Software
17    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 
19    Please email any bugs, comments, and/or additions to this file to:
20    bug-gdb@prep.ai.mit.edu  */
21 
22 #include <signal.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <string.h>
26 #include <sys/time.h>
27 
28 enum level { MAIN, OUTER, INNER, LEAF, NR_LEVELS };
29 
30 /* Levels completed flag.  */
31 volatile enum level level = NR_LEVELS;
32 
33 void catcher (int signal);
34 
35 void
36 thrower (enum level next_level, int sig, int itimer, int on_stack)
37 {
38   level = next_level;
39   /* Set up the signal handler.  */
40   {
41     struct sigaction act;
42     memset (&act, 0, sizeof (act));
43     act.sa_handler = catcher;
44     act.sa_flags |= on_stack;
45     sigaction (sig, &act, NULL);
46   }
47   /* Set up a one-off timer.  A timer, rather than SIGSEGV, is used as
48      after a timer handler finishes the interrupted code can safely
49      resume.  */
50   {
51     struct itimerval itime;
52     memset (&itime, 0, sizeof (itime));
53     itime.it_value.tv_usec = 250 * 1000;
54     setitimer (itimer, &itime, NULL);
55   }
56   /* Wait.  */
57   while (level != LEAF);
58 }
59 
60 void
61 catcher (int signal)
62 {
63   /* Find the next level.  */
64   switch (level)
65     {
66     case MAIN:
67       thrower (OUTER, SIGALRM, ITIMER_REAL, SA_ONSTACK);
68       break;
69     case OUTER:
70       thrower (INNER, SIGVTALRM, ITIMER_VIRTUAL, SA_ONSTACK);
71       break;
72     case INNER:
73       level = LEAF;
74       return;
75     }
76 }
77 
78 
79 main ()
80 {
81   /* Set up the altstack.  */
82   {
83     static char stack[SIGSTKSZ * NR_LEVELS];
84     struct sigaltstack alt;
85     memset (&alt, 0, sizeof (alt));
86     alt.ss_sp = stack;
87     alt.ss_size = SIGSTKSZ;
88     alt.ss_flags = 0;
89     if (sigaltstack (&alt, NULL) < 0)
90       {
91 	perror ("sigaltstack");
92 	exit (0);
93       }
94   }
95   level = MAIN;
96   catcher (0);
97 }
98