1/* Return list with names for address in backtrace.
2 Copyright (C) 1998-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <assert.h>
21#include <execinfo.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25
26#include <ldsodefs.h>
27
28#if __ELF_NATIVE_CLASS == 32
29# define WORD_WIDTH 8
30#else
31/* We assume 64bits. */
32# define WORD_WIDTH 16
33#endif
34
35
36char **
37__backtrace_symbols (void *const *array, int size)
38{
39 Dl_info info[size];
40 int status[size];
41 int cnt;
42 size_t total = 0;
43 char **result;
44
45 /* Fill in the information we can get from `dladdr'. */
46 for (cnt = 0; cnt < size; ++cnt)
47 {
48 struct link_map *map;
49 status[cnt] = _dl_addr (array[cnt], &info[cnt], &map, NULL);
50 if (status[cnt] && info[cnt].dli_fname && info[cnt].dli_fname[0] != '\0')
51 {
52 /* We have some info, compute the length of the string which will be
53 "<file-name>(<sym-name>+offset) [address]. */
54 total += (strlen (info[cnt].dli_fname ?: "")
55 + strlen (info[cnt].dli_sname ?: "")
56 + 3 + WORD_WIDTH + 3 + WORD_WIDTH + 5);
57
58 /* The load bias is more useful to the user than the load
59 address. The use of these addresses is to calculate an
60 address in the ELF file, so its prelinked bias is not
61 something we want to subtract out. */
62 info[cnt].dli_fbase = (void *) map->l_addr;
63 }
64 else
65 total += 5 + WORD_WIDTH;
66 }
67
68 /* Allocate memory for the result. */
69 result = (char **) malloc (size * sizeof (char *) + total);
70 if (result != NULL)
71 {
72 char *last = (char *) (result + size);
73
74 for (cnt = 0; cnt < size; ++cnt)
75 {
76 result[cnt] = last;
77
78 if (status[cnt]
79 && info[cnt].dli_fname != NULL && info[cnt].dli_fname[0] != '\0')
80 {
81 if (info[cnt].dli_sname == NULL)
82 /* We found no symbol name to use, so describe it as
83 relative to the file. */
84 info[cnt].dli_saddr = info[cnt].dli_fbase;
85
86 if (info[cnt].dli_sname == NULL && info[cnt].dli_saddr == 0)
87 last += 1 + sprintf (last, "%s(%s) [%p]",
88 info[cnt].dli_fname ?: "",
89 info[cnt].dli_sname ?: "",
90 array[cnt]);
91 else
92 {
93 char sign;
94 ptrdiff_t offset;
95 if (array[cnt] >= (void *) info[cnt].dli_saddr)
96 {
97 sign = '+';
98 offset = array[cnt] - info[cnt].dli_saddr;
99 }
100 else
101 {
102 sign = '-';
103 offset = info[cnt].dli_saddr - array[cnt];
104 }
105
106 last += 1 + sprintf (last, "%s(%s%c%#tx) [%p]",
107 info[cnt].dli_fname ?: "",
108 info[cnt].dli_sname ?: "",
109 sign, offset, array[cnt]);
110 }
111 }
112 else
113 last += 1 + sprintf (last, "[%p]", array[cnt]);
114 }
115 assert (last <= (char *) result + size * sizeof (char *) + total);
116 }
117
118 return result;
119}
120weak_alias (__backtrace_symbols, backtrace_symbols)
121