freebsd-dev/lib/libc/gen/telldir.c
John Baldwin 18ae4fcc47 If telldir() is called immediately after a call to seekdir(), POSIX
requires the return value of telldir() to equal the value passed to
seekdir().  The current seekdir code with SINGLEUSE enabled breaks
this case as each call to telldir() allocates a new cookie.  Instead,
remove the SINGLEUSE code and change telldir() to look for an existing
cookie for the directory's current location rather than always creating
a new cookie.

CR:		https://phabric.freebsd.org/D490
PR:		121656
Reviewed by:	jilles
MFC after:	1 week
2014-07-29 00:16:33 +00:00

132 lines
3.6 KiB
C

/*
* 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.
* 4. 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/param.h>
#include <sys/queue.h>
#include <dirent.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include "un-namespace.h"
#include "libc_private.h"
#include "gen-private.h"
#include "telldir.h"
/*
* return a pointer into a directory
*/
long
telldir(dirp)
DIR *dirp;
{
struct ddloc *lp;
long idx;
if (__isthreaded)
_pthread_mutex_lock(&dirp->dd_lock);
LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
if (lp->loc_seek == dirp->dd_seek &&
lp->loc_loc == dirp->dd_loc)
break;
}
if (lp == NULL) {
lp = malloc(sizeof(struct ddloc));
if (lp == NULL) {
if (__isthreaded)
_pthread_mutex_unlock(&dirp->dd_lock);
return (-1);
}
lp->loc_index = dirp->dd_td->td_loccnt++;
lp->loc_seek = dirp->dd_seek;
lp->loc_loc = dirp->dd_loc;
LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
}
idx = lp->loc_index;
if (__isthreaded)
_pthread_mutex_unlock(&dirp->dd_lock);
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 dirent *dp;
LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
if (lp->loc_index == loc)
break;
}
if (lp == NULL)
return;
if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
return;
(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_unlocked(dirp, 0);
if (dp == NULL)
break;
}
}
/*
* Reclaim memory for telldir cookies which weren't used.
*/
void
_reclaim_telldir(dirp)
DIR *dirp;
{
struct ddloc *lp;
struct ddloc *templp;
lp = LIST_FIRST(&dirp->dd_td->td_locq);
while (lp != NULL) {
templp = lp;
lp = LIST_NEXT(lp, loc_lqe);
free(templp);
}
LIST_INIT(&dirp->dd_td->td_locq);
}