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1 | /* fileline.c -- Get file and line number information in a backtrace. |
2 | Copyright (C) 2012 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 <fcntl.h> | |
38 | ||
39 | #include "backtrace.h" | |
40 | #include "internal.h" | |
41 | ||
42 | /* Initialize the fileline information from the executable. Returns 1 | |
43 | on success, 0 on failure. */ | |
44 | ||
45 | static int | |
46 | fileline_initialize (struct backtrace_state *state, | |
47 | backtrace_error_callback error_callback, void *data) | |
48 | { | |
49 | int failed; | |
50 | fileline fileline_fn; | |
51 | int descriptor; | |
52 | ||
53 | failed = state->fileline_initialization_failed; | |
54 | ||
55 | if (state->threaded) | |
56 | { | |
57 | /* Use __sync_bool_compare_and_swap to do an atomic load. */ | |
58 | while (!__sync_bool_compare_and_swap | |
59 | (&state->fileline_initialization_failed, failed, failed)) | |
60 | failed = state->fileline_initialization_failed; | |
61 | } | |
62 | ||
63 | if (failed) | |
64 | { | |
65 | error_callback (data, "failed to read executable information", 0); | |
66 | return 0; | |
67 | } | |
68 | ||
69 | fileline_fn = state->fileline_fn; | |
70 | if (state->threaded) | |
71 | { | |
72 | while (!__sync_bool_compare_and_swap (&state->fileline_fn, fileline_fn, | |
73 | fileline_fn)) | |
74 | fileline_fn = state->fileline_fn; | |
75 | } | |
76 | if (fileline_fn != NULL) | |
77 | return 1; | |
78 | ||
79 | /* We have not initialized the information. Do it now. */ | |
80 | ||
81 | if (state->filename != NULL) | |
82 | descriptor = backtrace_open (state->filename, error_callback, data); | |
83 | else | |
84 | descriptor = backtrace_open ("/proc/self/exe", error_callback, data); | |
85 | if (descriptor < 0) | |
86 | failed = 1; | |
87 | ||
88 | if (!failed) | |
89 | { | |
90 | if (!backtrace_initialize (state, descriptor, error_callback, data, | |
91 | &fileline_fn)) | |
92 | failed = 1; | |
93 | } | |
94 | ||
95 | if (failed) | |
96 | { | |
97 | if (!state->threaded) | |
98 | state->fileline_initialization_failed = 1; | |
99 | else | |
100 | __sync_bool_compare_and_swap (&state->fileline_initialization_failed, | |
101 | 0, failed); | |
102 | return 0; | |
103 | } | |
104 | ||
105 | if (!state->threaded) | |
106 | state->fileline_fn = fileline_fn; | |
107 | else | |
108 | { | |
109 | __sync_bool_compare_and_swap (&state->fileline_fn, NULL, fileline_fn); | |
110 | ||
111 | /* At this point we know that state->fileline_fn is not NULL. | |
112 | Either we stored our value, or some other thread stored its | |
113 | value. If some other thread stored its value, we leak the | |
114 | one we just initialized. Either way, state->fileline_fn is | |
115 | initialized. The compare_and_swap is a full memory barrier, | |
116 | so we should have full access to that value even if it was | |
117 | created by another thread. */ | |
118 | } | |
119 | ||
120 | return 1; | |
121 | } | |
122 | ||
123 | /* Given a PC, find the file name, line number, and function name. */ | |
124 | ||
125 | int | |
126 | backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc, | |
127 | backtrace_full_callback callback, | |
128 | backtrace_error_callback error_callback, void *data) | |
129 | { | |
130 | if (!fileline_initialize (state, error_callback, data)) | |
131 | return 0; | |
132 | ||
133 | if (state->fileline_initialization_failed) | |
134 | return 0; | |
135 | ||
136 | return state->fileline_fn (state, pc, callback, error_callback, data); | |
137 | } | |
138 | ||
139 | /* Given a PC, find the symbol for it, and its value. */ | |
140 | ||
141 | int | |
142 | backtrace_syminfo (struct backtrace_state *state, uintptr_t pc, | |
143 | backtrace_syminfo_callback callback, | |
144 | backtrace_error_callback error_callback, void *data) | |
145 | { | |
146 | if (!fileline_initialize (state, error_callback, data)) | |
147 | return 0; | |
148 | ||
149 | if (state->fileline_initialization_failed) | |
150 | return 0; | |
151 | ||
152 | state->syminfo_fn (state, pc, callback, error_callback, data); | |
153 | return 1; | |
154 | } |