1/* libunwind - a platform-independent unwind library
2   Copyright (C) 2004 Hewlett-Packard Co
3	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4
5Permission is hereby granted, free of charge, to any person obtaining
6a copy of this software and associated documentation files (the
7"Software"), to deal in the Software without restriction, including
8without limitation the rights to use, copy, modify, merge, publish,
9distribute, sublicense, and/or sell copies of the Software, and to
10permit persons to whom the Software is furnished to do so, subject to
11the following conditions:
12
13The above copyright notice and this permission notice shall be
14included in all copies or substantial portions of the Software.
15
16THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
23
24/* Check whether basic unwinding truly is async-signal safe.  */
25
26#ifdef HAVE_CONFIG_H
27#include "config.h"
28#endif
29
30#include "compiler.h"
31
32#include <signal.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37
38#include <sys/time.h>
39
40#define UNW_LOCAL_ONLY
41#include <libunwind.h>
42
43static const int nerrors_max = 100;
44
45struct itimerval interval =
46  {
47    .it_interval = { .tv_sec = 0, .tv_usec = 0 },
48    .it_value    = { .tv_sec = 0, .tv_usec = 1000 }
49  };
50
51int verbose;
52int nerrors;
53int sigcount;
54
55#ifndef CONFIG_BLOCK_SIGNALS
56/* When libunwind is configured with --enable-block-signals=no, the caller
57   is responsible for preventing recursion via signal handlers.
58   We use a simple global here.  In a multithreaded program, one would use
59   a thread-local variable.  */
60int recurcount;
61#endif
62
63#define panic(args...)					\
64	{ ++nerrors; fprintf (stderr, args); return; }
65
66static void
67do_backtrace (int may_print, int get_proc_name)
68{
69  char buf[512], name[256];
70  unw_cursor_t cursor;
71  unw_word_t ip, sp, off;
72  unw_context_t uc;
73  int ret;
74  int depth = 0;
75
76#ifndef CONFIG_BLOCK_SIGNALS
77  if (recurcount > 0)
78    return;
79  recurcount += 1;
80#endif
81
82  unw_getcontext (&uc);
83  if (unw_init_local (&cursor, &uc) < 0)
84    panic ("unw_init_local failed!\n");
85
86  do
87    {
88      unw_get_reg (&cursor, UNW_REG_IP, &ip);
89      unw_get_reg (&cursor, UNW_REG_SP, &sp);
90
91      buf[0] = '\0';
92      if (get_proc_name || (may_print && verbose))
93	{
94	  ret = unw_get_proc_name (&cursor, name, sizeof (name), &off);
95	  if (ret == 0 && (may_print && verbose))
96	    {
97	      if (off)
98		snprintf (buf, sizeof (buf), "<%s+0x%lx>", name, (long) off);
99	      else
100		{
101		  size_t len = strlen (name);
102		  buf[0] = '<';
103		  memcpy (buf + 1, name, len);
104		  buf[len + 1] = '>';
105		  buf[len + 2] = '\0';
106		}
107	    }
108	}
109
110      if (may_print && verbose)
111	printf ("%016lx %-32s (sp=%016lx)\n", (long) ip, buf, (long) sp);
112
113      ret = unw_step (&cursor);
114      if (ret < 0)
115	{
116	  unw_get_reg (&cursor, UNW_REG_IP, &ip);
117	  panic ("FAILURE: unw_step() returned %d for ip=%lx\n",
118		 ret, (long) ip);
119	}
120      if (depth++ > 100)
121        {
122	  panic ("FAILURE: unw_step() looping over %d iterations\n", depth);
123	  break;
124        }
125    }
126  while (ret > 0);
127
128#ifndef CONFIG_BLOCK_SIGNALS
129  recurcount -= 1;
130#endif
131}
132
133void
134sighandler (int signal)
135{
136  if (verbose)
137    printf ("sighandler(signal=%d, count=%d)\n", signal, sigcount);
138
139  do_backtrace (1, 1);
140
141  ++sigcount;
142
143  if (sigcount == 100)
144    unw_set_caching_policy (unw_local_addr_space, UNW_CACHE_GLOBAL);
145  else if (sigcount == 200)
146    unw_set_caching_policy (unw_local_addr_space, UNW_CACHE_PER_THREAD);
147  else if (sigcount == 300 || nerrors > nerrors_max)
148    {
149      if (nerrors > nerrors_max)
150        panic ("Too many errors (%d)\n", nerrors);
151      if (nerrors)
152	{
153	  fprintf (stderr, "FAILURE: detected %d errors\n", nerrors);
154	  exit (-1);
155	}
156      if (verbose)
157	printf ("SUCCESS.\n");
158      exit (0);
159    }
160  setitimer (ITIMER_VIRTUAL, &interval, NULL);
161}
162
163int
164main (int argc, char **argv UNUSED)
165{
166  struct sigaction act;
167  long i = 0;
168
169  if (argc > 1)
170    verbose = 1;
171
172  unw_set_caching_policy (unw_local_addr_space, UNW_CACHE_NONE);
173
174  memset (&act, 0, sizeof (act));
175  act.sa_handler = sighandler;
176  act.sa_flags = SA_SIGINFO;
177  sigaction (SIGVTALRM, &act, NULL);
178
179  setitimer (ITIMER_VIRTUAL, &interval, NULL);
180
181  while (1)
182    {
183      if (0 && verbose)
184	printf ("%s: starting backtrace\n", __FUNCTION__);
185      do_backtrace (0, (i++ % 100) == 0);
186      if (nerrors > nerrors_max)
187        {
188	  fprintf (stderr, "Too many errors (%d)\n", nerrors);
189	  exit (-1);
190        }
191    }
192  return (0);
193}
194