151 lines
4.3 KiB
C
151 lines
4.3 KiB
C
/* $NetBSD: telldir.c,v 1.15 2003/08/07 16:42:58 agc 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 1.15 2003/08/07 16:42:58 agc Exp $");
|
|
#endif
|
|
#endif /* LIBC_SCCS and not lint */
|
|
|
|
#include "namespace.h"
|
|
#include "reentrant.h"
|
|
#include <sys/param.h>
|
|
|
|
#include <assert.h>
|
|
#include <dirent.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
|
|
#ifdef __weak_alias
|
|
__weak_alias(telldir,_telldir)
|
|
#endif
|
|
|
|
/*
|
|
* The option SINGLEUSE may be defined to say that a telldir
|
|
* cookie may be used only once before it is freed. This option
|
|
* is used to avoid having memory usage grow without bound.
|
|
*/
|
|
#define SINGLEUSE
|
|
|
|
/*
|
|
* One of these structures is malloced to describe the current directory
|
|
* position each time telldir is called. It records the current magic
|
|
* cookie returned by getdirentries and the offset within the buffer
|
|
* associated with that return value.
|
|
*/
|
|
struct ddloc {
|
|
struct ddloc *loc_next;/* next structure in list */
|
|
long loc_index; /* key associated with structure */
|
|
off_t loc_seek; /* magic cookie returned by getdirentries */
|
|
long loc_loc; /* offset of entry in buffer */
|
|
};
|
|
|
|
#define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */
|
|
#define LOCHASH(i) (((int)i)&(NDIRHASH-1))
|
|
|
|
static long dd_loccnt; /* Index of entry for sequential readdir's */
|
|
static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */
|
|
|
|
/*
|
|
* return a pointer into a directory
|
|
*/
|
|
long
|
|
telldir(dirp)
|
|
const DIR *dirp;
|
|
{
|
|
long idx;
|
|
struct ddloc *lp;
|
|
|
|
#ifdef _REENTRANT
|
|
if (__isthreaded)
|
|
mutex_lock((mutex_t *)dirp->dd_lock);
|
|
#endif
|
|
|
|
if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
|
|
return (-1);
|
|
idx = dd_loccnt++;
|
|
lp->loc_index = idx;
|
|
lp->loc_seek = dirp->dd_seek;
|
|
lp->loc_loc = dirp->dd_loc;
|
|
lp->loc_next = dd_hash[LOCHASH(idx)];
|
|
dd_hash[LOCHASH(idx)] = lp;
|
|
#ifdef _REENTRANT
|
|
if (__isthreaded)
|
|
mutex_unlock((mutex_t *)dirp->dd_lock);
|
|
#endif
|
|
return (idx);
|
|
}
|
|
|
|
/*
|
|
* seek to an entry in a directory.
|
|
* Only values returned by "telldir" should be passed to seekdir.
|
|
*/
|
|
void
|
|
__seekdir(dirp, loc)
|
|
DIR *dirp;
|
|
long loc;
|
|
{
|
|
struct ddloc *lp;
|
|
struct ddloc **prevlp;
|
|
struct dirent *dp;
|
|
|
|
_DIAGASSERT(dirp != NULL);
|
|
|
|
prevlp = &dd_hash[LOCHASH(loc)];
|
|
lp = *prevlp;
|
|
while (lp != NULL) {
|
|
if (lp->loc_index == loc)
|
|
break;
|
|
prevlp = &lp->loc_next;
|
|
lp = lp->loc_next;
|
|
}
|
|
if (lp == NULL)
|
|
return;
|
|
if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
|
|
goto found;
|
|
(void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
|
|
dirp->dd_seek = lp->loc_seek;
|
|
dirp->dd_loc = 0;
|
|
while (dirp->dd_loc < lp->loc_loc) {
|
|
dp = readdir(dirp);
|
|
if (dp == NULL)
|
|
break;
|
|
}
|
|
found:
|
|
#ifdef SINGLEUSE
|
|
*prevlp = lp->loc_next;
|
|
free(lp);
|
|
#endif
|
|
}
|