1/* fileline.c -- Get file and line number information in a backtrace.
2 Copyright (C) 2012-2017 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Google.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are
7met:
8
9 (1) Redistributions of source code must retain the above copyright
10 notice, this list of conditions and the following disclaimer.
11
12 (2) Redistributions in binary form must reproduce the above copyright
13 notice, this list of conditions and the following disclaimer in
14 the documentation and/or other materials provided with the
15 distribution.
16
17 (3) The name of the author may not be used to
18 endorse or promote products derived from this software without
19 specific prior written permission.
20
21THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31POSSIBILITY OF SUCH DAMAGE. */
32
33#include "config.h"
34
35#include <sys/types.h>
36#include <sys/stat.h>
37#include <errno.h>
38#include <fcntl.h>
39#include <stdlib.h>
40#include <unistd.h>
41
42#include "backtrace.h"
43#include "internal.h"
44
45#ifndef HAVE_GETEXECNAME
46#define getexecname() NULL
47#endif
48
49/* Initialize the fileline information from the executable. Returns 1
50 on success, 0 on failure. */
51
52static int
53fileline_initialize (struct backtrace_state *state,
54 backtrace_error_callback error_callback, void *data)
55{
56 int failed;
57 fileline fileline_fn;
58 int pass;
59 int called_error_callback;
60 int descriptor;
61 const char *filename;
62 char buf[64];
63
64 if (!state->threaded)
65 failed = state->fileline_initialization_failed;
66 else
67 failed = backtrace_atomic_load_int (&state->fileline_initialization_failed);
68
69 if (failed)
70 {
71 error_callback (data, "failed to read executable information", -1);
72 return 0;
73 }
74
75 if (!state->threaded)
76 fileline_fn = state->fileline_fn;
77 else
78 fileline_fn = backtrace_atomic_load_pointer (&state->fileline_fn);
79 if (fileline_fn != NULL)
80 return 1;
81
82 /* We have not initialized the information. Do it now. */
83
84 descriptor = -1;
85 called_error_callback = 0;
86 for (pass = 0; pass < 5; ++pass)
87 {
88 int does_not_exist;
89
90 switch (pass)
91 {
92 case 0:
93 filename = state->filename;
94 break;
95 case 1:
96 filename = getexecname ();
97 break;
98 case 2:
99 filename = "/proc/self/exe";
100 break;
101 case 3:
102 filename = "/proc/curproc/file";
103 break;
104 case 4:
105 snprintf (buf, sizeof (buf), "/proc/%ld/object/a.out",
106 (long) getpid ());
107 filename = buf;
108 break;
109 default:
110 abort ();
111 }
112
113 if (filename == NULL)
114 continue;
115
116 descriptor = backtrace_open (filename, error_callback, data,
117 &does_not_exist);
118 if (descriptor < 0 && !does_not_exist)
119 {
120 called_error_callback = 1;
121 break;
122 }
123 if (descriptor >= 0)
124 break;
125 }
126
127 if (descriptor < 0)
128 {
129 if (!called_error_callback)
130 {
131 if (state->filename != NULL)
132 error_callback (data, state->filename, ENOENT);
133 else
134 error_callback (data,
135 "libbacktrace could not find executable to open",
136 0);
137 }
138 failed = 1;
139 }
140
141 if (!failed)
142 {
143 if (!backtrace_initialize (state, filename, descriptor, error_callback,
144 data, &fileline_fn))
145 failed = 1;
146 }
147
148 if (failed)
149 {
150 if (!state->threaded)
151 state->fileline_initialization_failed = 1;
152 else
153 backtrace_atomic_store_int (&state->fileline_initialization_failed, 1);
154 return 0;
155 }
156
157 if (!state->threaded)
158 state->fileline_fn = fileline_fn;
159 else
160 {
161 backtrace_atomic_store_pointer (&state->fileline_fn, fileline_fn);
162
163 /* Note that if two threads initialize at once, one of the data
164 sets may be leaked. */
165 }
166
167 return 1;
168}
169
170/* Given a PC, find the file name, line number, and function name. */
171
172int
173backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc,
174 backtrace_full_callback callback,
175 backtrace_error_callback error_callback, void *data)
176{
177 if (!fileline_initialize (state, error_callback, data))
178 return 0;
179
180 if (state->fileline_initialization_failed)
181 return 0;
182
183 return state->fileline_fn (state, pc, callback, error_callback, data);
184}
185
186/* Given a PC, find the symbol for it, and its value. */
187
188int
189backtrace_syminfo (struct backtrace_state *state, uintptr_t pc,
190 backtrace_syminfo_callback callback,
191 backtrace_error_callback error_callback, void *data)
192{
193 if (!fileline_initialize (state, error_callback, data))
194 return 0;
195
196 if (state->fileline_initialization_failed)
197 return 0;
198
199 state->syminfo_fn (state, pc, callback, error_callback, data);
200 return 1;
201}
202