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/*
* 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(DIR *dirp)
{
struct ddloc_mem *lp, *flp;
union ddloc_packed ddloc;
if (__isthreaded)
_pthread_mutex_lock(&dirp->dd_lock);
/*
* Outline:
* 1) If the directory position fits in a packed structure, return that.
* 2) Otherwise, see if it's already been recorded in the linked list
* 3) Otherwise, malloc a new one
*/
if (dirp->dd_seek < (1ul << DD_SEEK_BITS) &&
dirp->dd_loc < (1ul << DD_LOC_BITS)) {
ddloc.s.is_packed = 1;
ddloc.s.loc = dirp->dd_loc;
ddloc.s.seek = dirp->dd_seek;
goto out;
}
flp = NULL;
LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
if (lp->loc_seek == dirp->dd_seek) {
if (flp == NULL)
flp = lp;
if (lp->loc_loc == dirp->dd_loc)
break;
} else if (flp != NULL) {
lp = NULL;
break;
}
}
if (lp == NULL) {
lp = malloc(sizeof(struct ddloc_mem));
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;
if (flp != NULL)
LIST_INSERT_BEFORE(flp, lp, loc_lqe);
else
LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
}
ddloc.i.is_packed = 0;
/*
* Technically this assignment could overflow on 32-bit architectures,
* but we would get ENOMEM long before that happens.
*/
ddloc.i.index = lp->loc_index;
out:
if (__isthreaded)
_pthread_mutex_unlock(&dirp->dd_lock);
return (ddloc.l);
}
/*
* seek to an entry in a directory.
* Only values returned by "telldir" should be passed to seekdir.
*/
void
_seekdir(DIR *dirp, long loc)
{
struct ddloc_mem *lp;
struct dirent *dp;
union ddloc_packed ddloc;
off_t loc_seek;
long loc_loc;
ddloc.l = loc;
if (ddloc.s.is_packed) {
loc_seek = ddloc.s.seek;
loc_loc = ddloc.s.loc;
} else {
LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
if (lp->loc_index == ddloc.i.index)
break;
}
if (lp == NULL)
return;
loc_seek = lp->loc_seek;
loc_loc = lp->loc_loc;
}
if (loc_loc == dirp->dd_loc && loc_seek == dirp->dd_seek)
return;
/* If it's within the same chunk of data, don't bother reloading. */
if (loc_seek == dirp->dd_seek) {
/*
* If we go back to 0 don't make the next readdir
* trigger a call to getdirentries().
*/
if (loc_loc == 0)
dirp->dd_flags |= __DTF_SKIPREAD;
dirp->dd_loc = loc_loc;
return;
}
(void) lseek(dirp->dd_fd, (off_t)loc_seek, SEEK_SET);
dirp->dd_seek = loc_seek;
dirp->dd_loc = 0;
dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */
while (dirp->dd_loc < loc_loc) {
dp = _readdir_unlocked(dirp, 0);
if (dp == NULL)
break;
}
}
/*
* After readdir returns the last entry in a block, a call to telldir
* returns a location that is after the end of that last entry.
* However, that location doesn't refer to a valid directory entry.
* Ideally, the call to telldir would return a location that refers to
* the first entry in the next block. That location is not known
* until the next block is read, so readdir calls this function after
* fetching a new block to fix any such telldir locations.
*/
void
_fixtelldir(DIR *dirp, long oldseek, long oldloc)
{
struct ddloc_mem *lp;
lp = LIST_FIRST(&dirp->dd_td->td_locq);
if (lp != NULL) {
if (lp->loc_loc == oldloc &&
lp->loc_seek == oldseek) {
lp->loc_seek = dirp->dd_seek;
lp->loc_loc = dirp->dd_loc;
}
}
}
/*
* Reclaim memory for telldir cookies which weren't used.
*/
void
_reclaim_telldir(DIR *dirp)
{
struct ddloc_mem *lp;
struct ddloc_mem *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);
}
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