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unwind.c revision 1.2.26.2 
      1 /*	$NetBSD: unwind.c,v 1.2.26.2 2020/04/08 14:07:14 martin 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
     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_FOREIGN_EXCEPTION_CAUGHT;
     57 	return 0;
     58 }
     59 
     60 size_t
     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 && ctx.n > 0)
     71 		ctx.arr[--ctx.n] = NULL;	/* Skip frame below __start */
     72 
     73 	return ctx.n;
     74 }
     75