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e40bca1e | 1 | /* Return backtrace of current program state. |
b168057a | 2 | Copyright (C) 2003-2015 Free Software Foundation, Inc. |
e40bca1e UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Jakub Jelinek <jakub@redhat.com>, 2003. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ | |
e40bca1e UD |
19 | |
20 | #include <bits/libc-lock.h> | |
21 | #include <dlfcn.h> | |
22 | #include <execinfo.h> | |
23 | #include <stdlib.h> | |
24 | #include <unwind.h> | |
25 | ||
26 | struct trace_arg | |
27 | { | |
28 | void **array; | |
29 | _Unwind_Word cfa; | |
30 | int cnt; | |
31 | int size; | |
32 | }; | |
33 | ||
34 | #ifdef SHARED | |
35 | static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *); | |
36 | static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *); | |
37 | static _Unwind_Word (*unwind_getcfa) (struct _Unwind_Context *); | |
38 | static void *libgcc_handle; | |
39 | ||
40 | ||
41 | /* Dummy version in case libgcc_s does not contain the real code. */ | |
42 | static _Unwind_Word | |
43 | dummy_getcfa (struct _Unwind_Context *ctx __attribute__ ((unused))) | |
44 | { | |
45 | return 0; | |
46 | } | |
47 | ||
48 | ||
49 | static void | |
50 | init (void) | |
51 | { | |
52 | libgcc_handle = __libc_dlopen ("libgcc_s.so.1"); | |
53 | ||
54 | if (libgcc_handle == NULL) | |
55 | return; | |
56 | ||
57 | unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace"); | |
58 | unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP"); | |
59 | if (unwind_getip == NULL) | |
60 | unwind_backtrace = NULL; | |
61 | unwind_getcfa = (__libc_dlsym (libgcc_handle, "_Unwind_GetCFA") | |
62 | ?: dummy_getcfa); | |
63 | } | |
64 | #else | |
65 | # define unwind_backtrace _Unwind_Backtrace | |
66 | # define unwind_getip _Unwind_GetIP | |
67 | # define unwind_getcfa _Unwind_GetCFA | |
68 | #endif | |
69 | ||
70 | static _Unwind_Reason_Code | |
71 | backtrace_helper (struct _Unwind_Context *ctx, void *a) | |
72 | { | |
73 | struct trace_arg *arg = a; | |
74 | ||
75 | /* We are first called with address in the __backtrace function. | |
76 | Skip it. */ | |
77 | if (arg->cnt != -1) | |
78 | { | |
79 | arg->array[arg->cnt] = (void *) unwind_getip (ctx); | |
80 | ||
81 | /* Check whether we make any progress. */ | |
82 | _Unwind_Word cfa = unwind_getcfa (ctx); | |
83 | ||
84 | if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt] | |
85 | && cfa == arg->cfa) | |
86 | return _URC_END_OF_STACK; | |
87 | arg->cfa = cfa; | |
88 | } | |
89 | if (++arg->cnt == arg->size) | |
90 | return _URC_END_OF_STACK; | |
91 | return _URC_NO_REASON; | |
92 | } | |
93 | ||
94 | int | |
95 | __backtrace (array, size) | |
96 | void **array; | |
97 | int size; | |
98 | { | |
99 | struct trace_arg arg = { .array = array, .cfa = 0, .size = size, .cnt = -1 }; | |
100 | #ifdef SHARED | |
101 | __libc_once_define (static, once); | |
102 | ||
103 | __libc_once (once, init); | |
104 | if (unwind_backtrace == NULL) | |
105 | return 0; | |
106 | #endif | |
107 | ||
108 | if (size >= 1) | |
109 | unwind_backtrace (backtrace_helper, &arg); | |
110 | ||
305502f6 | 111 | /* _Unwind_Backtrace seems to put NULL address above |
e40bca1e UD |
112 | _start. Fix it up here. */ |
113 | if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL) | |
114 | --arg.cnt; | |
115 | return arg.cnt != -1 ? arg.cnt : 0; | |
116 | } | |
117 | weak_alias (__backtrace, backtrace) | |
118 | libc_hidden_def (__backtrace) | |
119 | ||
120 | ||
121 | #ifdef SHARED | |
122 | /* Free all resources if necessary. */ | |
123 | libc_freeres_fn (free_mem) | |
124 | { | |
125 | unwind_backtrace = NULL; | |
126 | if (libgcc_handle != NULL) | |
127 | { | |
128 | __libc_dlclose (libgcc_handle); | |
129 | libgcc_handle = NULL; | |
130 | } | |
131 | } | |
132 | #endif |