1/* backtrace.c -- Entry point for stack backtrace library.
2 Copyright (C) 2012-2025 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Google.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are
7met:
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
21THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31POSSIBILITY OF SUCH DAMAGE. */
32
33#include "config.h"
34
35#include <sys/types.h>
36
37#include "unwind.h"
38#include "backtrace.h"
39#include "internal.h"
40
41/* The main backtrace_full routine. */
42
43/* Data passed through _Unwind_Backtrace. */
44
45struct backtrace_data
46{
47 /* Number of frames to skip. */
48 int skip;
49 /* Library state. */
50 struct backtrace_state *state;
51 /* Callback routine. */
52 backtrace_full_callback callback;
53 /* Error callback routine. */
54 backtrace_error_callback error_callback;
55 /* Data to pass to callback routines. */
56 void *data;
57 /* Value to return from backtrace_full. */
58 int ret;
59 /* Whether there is any memory available. */
60 int can_alloc;
61};
62
63/* Unwind library callback routine. This is passed to
64 _Unwind_Backtrace. */
65
66static _Unwind_Reason_Code
67unwind (struct _Unwind_Context *context, void *vdata)
68{
69 struct backtrace_data *bdata = (struct backtrace_data *) vdata;
70 uintptr_t pc;
71 int ip_before_insn = 0;
72
73#ifdef HAVE_GETIPINFO
74 pc = _Unwind_GetIPInfo (context, &ip_before_insn);
75#else
76 pc = _Unwind_GetIP (context);
77#endif
78
79 if (bdata->skip > 0)
80 {
81 --bdata->skip;
82 return _URC_NO_REASON;
83 }
84
85 if (!ip_before_insn)
86 --pc;
87
88 if (!bdata->can_alloc)
89 bdata->ret = bdata->callback (bdata->data, pc, NULL, 0, NULL);
90 else
91 bdata->ret = backtrace_pcinfo (state: bdata->state, pc, callback: bdata->callback,
92 error_callback: bdata->error_callback, data: bdata->data);
93 if (bdata->ret != 0)
94 return _URC_END_OF_STACK;
95
96 return _URC_NO_REASON;
97}
98
99/* Get a stack backtrace. */
100
101int __attribute__((noinline))
102backtrace_full (struct backtrace_state *state, int skip,
103 backtrace_full_callback callback,
104 backtrace_error_callback error_callback, void *data)
105{
106 struct backtrace_data bdata;
107 void *p;
108
109 bdata.skip = skip + 1;
110 bdata.state = state;
111 bdata.callback = callback;
112 bdata.error_callback = error_callback;
113 bdata.data = data;
114 bdata.ret = 0;
115
116 /* If we can't allocate any memory at all, don't try to produce
117 file/line information. */
118 p = backtrace_alloc (state, size: 4096, NULL, NULL);
119 if (p == NULL)
120 bdata.can_alloc = 0;
121 else
122 {
123 backtrace_free (state, mem: p, size: 4096, NULL, NULL);
124 bdata.can_alloc = 1;
125 }
126
127 _Unwind_Backtrace (unwind, &bdata);
128 return bdata.ret;
129}
130

source code of libbacktrace/backtrace.c