1/* Return backtrace of current program state.
2 Copyright (C) 2003-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <execinfo.h>
20#include <stdlib.h>
21#include <unwind.h>
22#include <unwind-link.h>
23
24struct trace_arg
25{
26 void **array;
27 struct unwind_link *unwind_link;
28 _Unwind_Word cfa;
29 int cnt;
30 int size;
31};
32
33static _Unwind_Reason_Code
34backtrace_helper (struct _Unwind_Context *ctx, void *a)
35{
36 struct trace_arg *arg = a;
37
38 /* We are first called with address in the __backtrace function.
39 Skip it. */
40 if (arg->cnt != -1)
41 {
42 arg->array[arg->cnt]
43 = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetIP) (ctx);
44 if (arg->cnt > 0)
45 arg->array[arg->cnt]
46 = unwind_arch_adjustment (arg->array[arg->cnt - 1],
47 arg->array[arg->cnt]);
48
49 /* Check whether we make any progress. */
50 _Unwind_Word cfa
51 = UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetCFA) (ctx);
52
53 if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt]
54 && cfa == arg->cfa)
55 return _URC_END_OF_STACK;
56 arg->cfa = cfa;
57 }
58 if (++arg->cnt == arg->size)
59 return _URC_END_OF_STACK;
60 return _URC_NO_REASON;
61}
62
63int
64__backtrace (void **array, int size)
65{
66 struct trace_arg arg =
67 {
68 .array = array,
69 .unwind_link = __libc_unwind_link_get (),
70 .cfa = 0,
71 .size = size,
72 .cnt = -1
73 };
74
75 if (size <= 0 || arg.unwind_link == NULL)
76 return 0;
77
78 UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
79 (backtrace_helper, &arg);
80
81 /* _Unwind_Backtrace seems to put NULL address above
82 _start. Fix it up here. */
83 if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
84 --arg.cnt;
85 return arg.cnt != -1 ? arg.cnt : 0;
86}
87weak_alias (__backtrace, backtrace)
88libc_hidden_def (__backtrace)
89