1 /* $NetBSD: unwind.c,v 1.3 2019/01/30 22:46:49 mrg Exp $ */
2
3 /*-
4 * Copyright (c) 2012 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31 #include <sys/cdefs.h>
32 #include <sys/types.h>
33 #include <stdio.h>
34
35 #include "unwind.h"
36 #include "execinfo.h"
37
38 struct tracer_context {
39 void **arr;
40 size_t len;
41 size_t n;
42 };
43
44 static _Unwind_Reason_Code
tracer(struct _Unwind_Context * ctx,void * arg)45 tracer(struct _Unwind_Context *ctx, void *arg)
46 {
47 struct tracer_context *t = arg;
48 if (t->n == (size_t)~0) {
49 /* Skip backtrace frame */
50 t->n = 0;
51 return 0;
52 }
53 if (t->n < t->len)
54 t->arr[t->n++] = (void *)_Unwind_GetIP(ctx);
55 else
56 return _URC_END_OF_STACK;
57 return _URC_NO_REASON;
58 }
59
60 size_t
backtrace(void ** arr,size_t len)61 backtrace(void **arr, size_t len)
62 {
63 struct tracer_context ctx;
64
65 ctx.arr = arr;
66 ctx.len = len;
67 ctx.n = (size_t)~0;
68
69 _Unwind_Backtrace(tracer, &ctx);
70 if (ctx.n == (size_t)~0)
71 ctx.n = 0;
72 else if (ctx.n > 0)
73 ctx.arr[--ctx.n] = NULL; /* Skip frame below __start */
74
75 return ctx.n;
76 }
77