1 /* fileline.c -- Get file and line number information in a backtrace.
2 Copyright (C) 2012-2016 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Google.
4
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions are
7 met:
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
21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 POSSIBILITY 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
41 #include "backtrace.h"
42 #include "internal.h"
43
44 #ifndef HAVE_GETEXECNAME
45 #define getexecname() NULL
46 #endif
47
48 /* Initialize the fileline information from the executable. Returns 1
49 on success, 0 on failure. */
50
51 static int
fileline_initialize(struct backtrace_state * state,backtrace_error_callback error_callback,void * data)52 fileline_initialize (struct backtrace_state *state,
53 backtrace_error_callback error_callback, void *data)
54 {
55 int failed;
56 fileline fileline_fn;
57 int pass;
58 int called_error_callback;
59 int descriptor;
60
61 if (!state->threaded)
62 failed = state->fileline_initialization_failed;
63 else
64 failed = backtrace_atomic_load_int (&state->fileline_initialization_failed);
65
66 if (failed)
67 {
68 error_callback (data, "failed to read executable information", -1);
69 return 0;
70 }
71
72 if (!state->threaded)
73 fileline_fn = state->fileline_fn;
74 else
75 fileline_fn = backtrace_atomic_load_pointer (&state->fileline_fn);
76 if (fileline_fn != NULL)
77 return 1;
78
79 /* We have not initialized the information. Do it now. */
80
81 descriptor = -1;
82 called_error_callback = 0;
83 for (pass = 0; pass < 4; ++pass)
84 {
85 const char *filename;
86 int does_not_exist;
87
88 switch (pass)
89 {
90 case 0:
91 filename = state->filename;
92 break;
93 case 1:
94 filename = getexecname ();
95 break;
96 case 2:
97 filename = "/proc/self/exe";
98 break;
99 case 3:
100 filename = "/proc/curproc/file";
101 break;
102 default:
103 abort ();
104 }
105
106 if (filename == NULL)
107 continue;
108
109 descriptor = backtrace_open (filename, error_callback, data,
110 &does_not_exist);
111 if (descriptor < 0 && !does_not_exist)
112 {
113 called_error_callback = 1;
114 break;
115 }
116 if (descriptor >= 0)
117 break;
118 }
119
120 if (descriptor < 0)
121 {
122 if (!called_error_callback)
123 {
124 if (state->filename != NULL)
125 error_callback (data, state->filename, ENOENT);
126 else
127 error_callback (data,
128 "libbacktrace could not find executable to open",
129 0);
130 }
131 failed = 1;
132 }
133
134 if (!failed)
135 {
136 if (!backtrace_initialize (state, descriptor, error_callback, data,
137 &fileline_fn))
138 failed = 1;
139 }
140
141 if (failed)
142 {
143 if (!state->threaded)
144 state->fileline_initialization_failed = 1;
145 else
146 backtrace_atomic_store_int (&state->fileline_initialization_failed, 1);
147 return 0;
148 }
149
150 if (!state->threaded)
151 state->fileline_fn = fileline_fn;
152 else
153 {
154 backtrace_atomic_store_pointer (&state->fileline_fn, fileline_fn);
155
156 /* Note that if two threads initialize at once, one of the data
157 sets may be leaked. */
158 }
159
160 return 1;
161 }
162
163 /* Given a PC, find the file name, line number, and function name.
164 N.B. The result is not necessarily useful. It will be zero if
165 fileline_initialize fails, but it will also be zero if everything
166 succeeds and CALLBACK returns 0 (which is intended behavior for
167 CALLBACK: see backtrace.h:backtrace_full_callback). */
168
169 int
backtrace_pcinfo(struct backtrace_state * state,uintptr_t pc,backtrace_full_callback callback,backtrace_error_callback error_callback,void * data)170 backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc,
171 backtrace_full_callback callback,
172 backtrace_error_callback error_callback, void *data)
173 {
174 if (!fileline_initialize (state, error_callback, data))
175 return 0;
176
177 if (state->fileline_initialization_failed)
178 return 0;
179
180 return state->fileline_fn (state, pc, callback, error_callback, data);
181 }
182
183 /* Given a PC, find the symbol for it, and its value.
184 Returns non-zero on success, zero on failure.
185 N.B. If the result is "success" error_callback may still have been called.
186 Plus if the result is "success", a symbol may not have been found.
187 CALLBACK will be called with NULL parameter values if a symbol isn't found.
188 It is up to the caller to handle all of this appropriately. */
189
190 int
backtrace_syminfo(struct backtrace_state * state,uintptr_t pc,backtrace_syminfo_callback callback,backtrace_error_callback error_callback,void * data)191 backtrace_syminfo (struct backtrace_state *state, uintptr_t pc,
192 backtrace_syminfo_callback callback,
193 backtrace_error_callback error_callback, void *data)
194 {
195 if (!fileline_initialize (state, error_callback, data))
196 return 0;
197
198 if (state->fileline_initialization_failed)
199 return 0;
200
201 state->syminfo_fn (state, pc, callback, error_callback, data);
202 return 1;
203 }
204