/*      $OpenBSD: cancel.h,v 1.5 2017/09/05 02:40:54 guenther Exp $ */
/*
 * Copyright (c) 2015 Philip Guenther <guenther@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _CANCEL_H_
#define _CANCEL_H_

#include <tib.h>
#include "thread_private.h"

/* process a cancel request at a cancel point */
__dead void     _thread_canceled(void);

#ifdef __LIBC__
PROTO_NORMAL(_thread_canceled);
#endif

#if defined(__LIBC__) && !defined(TCB_HAVE_MD_GET)
/*
 * Override TIB_GET macro to use the caching callback
 */
#undef TIB_GET
#define TIB_GET()       TCB_TO_TIB(_thread_cb.tc_tcb())
#endif

#define PREP_CANCEL_POINT(tib)                                          \
        int _cantcancel = (tib)->tib_cantcancel

#define ENTER_CANCEL_POINT_INNER(tib, can_cancel, delay)                \
        if (_cantcancel == 0) {                                         \
                (tib)->tib_cancel_point = (delay) ?                     \
                    CANCEL_POINT_DELAYED : CANCEL_POINT;                \
                if (can_cancel) {                                       \
                        __asm volatile("":::"memory");                  \
                        if (__predict_false((tib)->tib_canceled))       \
                                _thread_canceled();                     \
                }                                                       \
        }

#define LEAVE_CANCEL_POINT_INNER(tib, can_cancel)                       \
        if (_cantcancel == 0) {                                         \
                (tib)->tib_cancel_point = 0;                            \
                if (can_cancel) {                                       \
                        __asm volatile("":::"memory");                  \
                        if (__predict_false((tib)->tib_canceled))       \
                                _thread_canceled();                     \
                }                                                       \
        }

/*
 * Enter or leave a cancelation point, optionally processing pending
 * cancelation requests.  Note that ENTER_CANCEL_POINT opens a block
 * and LEAVE_CANCEL_POINT must close that same block.
 */
#define ENTER_CANCEL_POINT(can_cancel)                                  \
    {                                                                   \
        struct tib *_tib = TIB_GET();                                   \
        PREP_CANCEL_POINT(_tib);                                        \
        ENTER_CANCEL_POINT_INNER(_tib, can_cancel, 0)

#define LEAVE_CANCEL_POINT(can_cancel)                                  \
        LEAVE_CANCEL_POINT_INNER(_tib, can_cancel);                     \
    }

#endif /* _CANCEL_H_ */