lib/libexecinfo/unwind.c

   1 /*      $NetBSD: unwind.c,v 1.2 2014/03/24 21:26:01 joerg 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         return 0;
  56 }
  57
  58 size_t
  59 backtrace(void **arr, size_t len)
  60 {
  61         struct tracer_context ctx;
  62
  63         ctx.arr = arr;
  64         ctx.len = len;
  65         ctx.n = (size_t)~0;
  66
  67         _Unwind_Backtrace(tracer, &ctx);
  68         if (ctx.n != (size_t)~0 && ctx.n > 0)
  69                 ctx.arr[--ctx.n] = NULL;        /* Skip frame below __start */
  70
  71         return ctx.n;
  72 }