minix/lib/libc/gen/telldir.c

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/* $NetBSD: telldir.c,v 1.20 2013/03/06 11:27:28 yamt Exp $ */
/*
* Copyright (c) 1983, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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)
#if 0
static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: telldir.c,v 1.20 2013/03/06 11:27:28 yamt Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
#include "reentrant.h"
#include "extern.h"
#include <sys/param.h>
#include <assert.h>
#include <dirent.h>
#include <stdlib.h>
#include <unistd.h>
#include "dirent_private.h"
#ifdef __weak_alias
__weak_alias(telldir,_telldir)
#endif
long
telldir(DIR *dirp)
{
long rv;
#ifdef _REENTRANT
if (__isthreaded) {
mutex_lock((mutex_t *)dirp->dd_lock);
rv = _telldir_unlocked(dirp);
mutex_unlock((mutex_t *)dirp->dd_lock);
} else
#endif
rv = _telldir_unlocked(dirp);
return rv;
}
/*
* return a pointer into a directory
*/
long
_telldir_unlocked(DIR *dirp)
{
struct dirpos *lp;
for (lp = dirp->dd_internal; lp; lp = lp->dp_next)
if (lp->dp_seek == dirp->dd_seek &&
lp->dp_loc == dirp->dd_loc)
return (intptr_t)lp;
if ((lp = malloc(sizeof(*lp))) == NULL)
return (-1);
lp->dp_seek = dirp->dd_seek;
lp->dp_loc = dirp->dd_loc;
lp->dp_next = dirp->dd_internal;
dirp->dd_internal = lp;
return (intptr_t)lp;
}
/*
* seek to an entry in a directory.
* Only values returned by "telldir" should be passed to seekdir.
*/
void
_seekdir_unlocked(DIR *dirp, long loc)
{
struct dirpos *lp;
_DIAGASSERT(dirp != NULL);
for (lp = dirp->dd_internal; lp; lp = lp->dp_next)
if ((intptr_t)lp == loc)
break;
if (lp == NULL)
return;
if (lp->dp_loc == dirp->dd_loc && lp->dp_seek == dirp->dd_seek)
return;
dirp->dd_seek = lseek(dirp->dd_fd, lp->dp_seek, SEEK_SET);
dirp->dd_loc = 0;
while (dirp->dd_loc < lp->dp_loc)
if (_readdir_unlocked(dirp, 0) == NULL)
break;
}