/*      $NetBSD: flockfile.c,v 1.11 2012/03/15 18:22:30 christos Exp $  */

/*-
 * Copyright (c) 2002 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nathan J. Williams.
 *
 * 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>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: flockfile.c,v 1.11 2012/03/15 18:22:30 christos Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include "reentrant.h"
#include "local.h"

#ifdef __weak_alias
__weak_alias(flockfile,_flockfile)
__weak_alias(ftrylockfile,_ftrylockfile)
__weak_alias(funlockfile,_funlockfile)
#endif

#ifdef _REENTRANT
/*
 * XXX This code makes the assumption that a thr_t (pthread_t) is a 
 * XXX pointer.
 */

void
flockfile(FILE *fp)
{

        __flockfile_internal(fp, 0);
}

int
ftrylockfile(FILE *fp)
{
        int retval;

        if (__isthreaded == 0)
                return 0;

        retval = 0;
        mutex_lock(&_LOCK(fp));
                
        if (_LOCKOWNER(fp) == thr_self()) {
                _LOCKCOUNT(fp)++;
        } else if (_LOCKOWNER(fp) == NULL) {
                _LOCKOWNER(fp) = thr_self();
                _LOCKCOUNT(fp) = 1;
        } else
                retval = -1;

        mutex_unlock(&_LOCK(fp));

        return retval;
}

void
funlockfile(FILE *fp)
{

        __funlockfile_internal(fp, 0);
}

void
__flockfile_internal(FILE *fp, int internal)
{

        if (__isthreaded == 0)
                return;

        mutex_lock(&_LOCK(fp));
        
        if (_LOCKOWNER(fp) == thr_self()) {
                _LOCKCOUNT(fp)++;
                if (internal)
                        _LOCKINTERNAL(fp)++;
        } else {
                /* danger! cond_wait() is a cancellation point. */
                int oldstate;
                thr_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
                while (_LOCKOWNER(fp) != NULL)
                        cond_wait(&_LOCKCOND(fp), &_LOCK(fp));
                thr_setcancelstate(oldstate, NULL);
                _LOCKOWNER(fp) = thr_self();
                _LOCKCOUNT(fp) = 1;
                if (internal)
                        _LOCKINTERNAL(fp) = 1;
        }

        if (_LOCKINTERNAL(fp) == 1)
                /* stash cancellation state and disable */
                thr_setcancelstate(PTHREAD_CANCEL_DISABLE,
                    &_LOCKCANCELSTATE(fp));

        mutex_unlock(&_LOCK(fp));
}
 
void
__funlockfile_internal(FILE *fp, int internal)
{

        if (__isthreaded == 0)
                return;

        mutex_lock(&_LOCK(fp));

        if (internal) {
                _LOCKINTERNAL(fp)--;
                if (_LOCKINTERNAL(fp) == 0)
                        thr_setcancelstate(_LOCKCANCELSTATE(fp), NULL);
        }

        _LOCKCOUNT(fp)--;
        if (_LOCKCOUNT(fp) == 0) {
                _LOCKOWNER(fp) = NULL;
                cond_signal(&_LOCKCOND(fp));
        }

        mutex_unlock(&_LOCK(fp));
}

#else /* _REENTRANT */

void
flockfile(FILE *fp)
{
        /* LINTED deliberate lack of effect */
        (void)fp;

        return;
}

int
ftrylockfile(FILE *fp)
{
        /* LINTED deliberate lack of effect */
        (void)fp;

        return 0;
}

void
funlockfile(FILE *fp)
{
        /* LINTED deliberate lack of effect */
        (void)fp;

        return;
}

#endif /* _REENTRANT */