aboutsummaryrefslogtreecommitdiff
path: root/src/common/backtrace.c
blob: d3f59b2c70734407c51606892e8c435324738a09 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/* Copyright (c) 2013, The Tor Project, Inc. */
/* See LICENSE for licensing information */

#include "orconfig.h"
#include "backtrace.h"
#include "compat.h"
#include "util.h"

#ifdef HAVE_EXECINFO_H
#include <execinfo.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \
  defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION)
#define USE_BACKTRACE
#endif

#if !defined(USE_BACKTRACE)
#define NO_BACKTRACE_IMPL
#endif

static char *bt_filename = NULL;
static char *bt_version = NULL;

#ifndef NO_BACKTRACE_IMPL
/**DOCDOC*/
static int
open_bt_target(void)
{
  int fd = -1;
  if (bt_filename)
    fd = open(bt_filename, O_WRONLY|O_CREAT|O_APPEND, 0700);
  return fd;
}
#endif

/**DOCDOC*/
static void
bt_write(int fd, const char *s, ssize_t n)
{
  int r;
  if (n < 0) n = strlen(s);

  r = write(STDERR_FILENO, s, n);
  if (fd >= 0)
    r = write(fd, s, n);
  (void)r; 
}

#ifdef USE_BACKTRACE
#define MAX_DEPTH 256
static void *cb_buf[MAX_DEPTH];

/**DOCDOC*/
void
dump_backtrace(const char *msg)
{
  char timebuf[32];
  time_t t = time(NULL);
  int timebuf_len;
  int depth;
  int fd;
  if (!msg) msg = "unspecified crash";

  depth = backtrace(cb_buf, MAX_DEPTH);

  t /= 900; t *= 900; /* Round to the previous 15 minutes */
  timebuf[0] = '\0';
  timebuf_len = format_dec_number_sigsafe(t, timebuf, sizeof(timebuf));

  fd = open_bt_target();
  bt_write(fd, "========================================"
               "====================================\n", -1);
  bt_write(fd, bt_version, -1);
  bt_write(fd, " died around T=", -1);
  bt_write(fd, timebuf, timebuf_len);
  bt_write(fd, ": ", 2);
  bt_write(fd, msg, -1);
  bt_write(fd, "\n", 1);
  backtrace_symbols_fd(cb_buf, depth, STDERR_FILENO);
  if (fd >= 0)
    backtrace_symbols_fd(cb_buf, depth, fd);

  close(fd);
}

/**DOCDOC*/
static int
install_bt_handler(void)
{
  /*XXXX add signal handlers */
  /*XXXX make this idempotent */
  return 0;
}
/**DOCDOC*/
static void
remove_bt_handler(void)
{
}
#endif

#ifdef NO_BACKTRACE_IMPL
/**DOCDOC*/
void
dump_backtrace(const char *msg)
{
  bt_write(-1, bt_version, -1);
  bt_write(-1, " died: ", -1);
  bt_write(-1, msg, -1);
  bt_write(-1, "\n", -1);
}

/**DOCDOC*/
static int
install_bt_handler(void)
{
  return 0;
}

/**DOCDOC*/
static void
remove_bt_handler(void)
{
}
#endif

/**DOCDOC*/
int
configure_backtrace_handler(const char *filename, const char *tor_version)
{
  tor_free(bt_filename);
  if (filename)
    bt_filename = tor_strdup(filename);
  tor_free(bt_version);
  if (!tor_version)
    tor_version = "Tor";
  bt_version = tor_strdup(tor_version);

  return install_bt_handler();
}

/**DOCDOC*/
void
clean_up_backtrace_handler(void)
{
  remove_bt_handler();

  tor_free(bt_filename);
  tor_free(bt_version);
}