/*	$NetBSD: unwind.c,v 1.3 2019/01/30 22:46:49 mrg Exp $	*/

/*-
 * Copyright (c) 2012 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/cdefs.h>
#include <sys/types.h>
#include <stdio.h>

#include "execinfo.h"

struct tracer_context {
	void **arr;
	size_t len;
	size_t n;
};

typedef enum {
  _URC_NO_REASON = 0,
#if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) && \
    !defined(__ARM_DWARF_EH__) && !defined(__SEH__)
  _URC_OK = 0, /* used by ARM EHABI */
#endif
  _URC_FOREIGN_EXCEPTION_CAUGHT = 1,

  _URC_FATAL_PHASE2_ERROR = 2,
  _URC_FATAL_PHASE1_ERROR = 3,
  _URC_NORMAL_STOP = 4,

  _URC_END_OF_STACK = 5,
  _URC_HANDLER_FOUND = 6,
  _URC_INSTALL_CONTEXT = 7,
  _URC_CONTINUE_UNWIND = 8,
#if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) && \
    !defined(__ARM_DWARF_EH__) && !defined(__SEH__)
  _URC_FAILURE = 9 /* used by ARM EHABI */
#endif
} _Unwind_Reason_Code;

struct _Unwind_Context;
typedef unsigned int _Unwind_Word __attribute__((__mode__(__unwind_word__)));

_Unwind_Word _Unwind_GetGR(struct _Unwind_Context *, int);
_Unwind_Word _Unwind_GetIP(struct _Unwind_Context *);
typedef _Unwind_Reason_Code (*_Unwind_Trace_Fn)(struct _Unwind_Context *,
                                                void *);
extern _Unwind_Reason_Code _Unwind_Backtrace (_Unwind_Trace_Fn, void *);
static _Unwind_Reason_Code
tracer(struct _Unwind_Context *ctx, void *arg)
{
	struct tracer_context *t = arg;
	if (t->n == (size_t)~0) {
		/* Skip backtrace frame */
		t->n = 0;
		return 0;
	}
	if (t->n < t->len)
		t->arr[t->n++] = (void *)_Unwind_GetIP(ctx);
	else
		return _URC_END_OF_STACK;
	return _URC_NO_REASON;
}

size_t
backtrace(void **arr, size_t len)
{
	struct tracer_context ctx;

	ctx.arr = arr;
	ctx.len = len;
	ctx.n = (size_t)~0;

	_Unwind_Backtrace(tracer, &ctx);
	if (ctx.n == (size_t)~0)
		ctx.n = 0;

	return ctx.n;
}