text: /*
   * 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: src/lib/libc/gen/telldir.c,v 1.11 2008/05/05 14:05:23 kib Exp $");
  
  #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 "telldir.h"
  
  /*
   * 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.
   */
  #if !__DARWIN_UNIX03
  #define SINGLEUSE
  #endif /* !__DARWIN_UNIX03 */
  
  /*
   * return a pointer into a directory
   */
  long
  telldir(dirp)
  	DIR *dirp;
  {
  	struct ddloc *lp;
  
  #if __DARWIN_UNIX03
  	if (__isthreaded)
  		_pthread_mutex_lock(&dirp->dd_lock);
  	LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
  		if (
  #if __DARWIN_64_BIT_INO_T
  		    (lp->loc_seek == dirp->dd_td->seekoff)
  #else /* !__DARWIN_64_BIT_INO_T */
  		    (lp->loc_seek == dirp->dd_seek)
  #endif /* __DARWIN_64_BIT_INO_T */
  		    && (lp->loc_loc == dirp->dd_loc))
  			goto found;
  	}
  	if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL) {
  		if (__isthreaded)
  			_pthread_mutex_unlock(&dirp->dd_lock);
  		return (-1);
  	}
  #else /* !__DARWIN_UNIX03 */
  	if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
  		return (-1);
  	if (__isthreaded)
  		_pthread_mutex_lock(&dirp->dd_lock);
  #endif /* __DARWIN_UNIX03 */
  	lp->loc_index = dirp->dd_td->td_loccnt++;
  #if __DARWIN_64_BIT_INO_T
  	lp->loc_seek = dirp->dd_td->seekoff;
  #else /* !__DARWIN_64_BIT_INO_T */
  	lp->loc_seek = dirp->dd_seek;
  #endif /* __DARWIN_64_BIT_INO_T */
  	lp->loc_loc = dirp->dd_loc;
  	LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
  #if __DARWIN_UNIX03
  found:
  #endif /* __DARWIN_UNIX03 */
  	if (__isthreaded)
  		_pthread_mutex_unlock(&dirp->dd_lock);
  	return (lp->loc_index);
  }
  
  /*
   * 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 && 
  #if __DARWIN_64_BIT_INO_T
  	    lp->loc_seek == dirp->dd_td->seekoff
  #else /* !__DARWIN_64_BIT_INO_T */
  	    lp->loc_seek == dirp->dd_seek
  #endif /* __DARWIN_64_BIT_INO_T */
  	)
  		goto found;
  	(void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
  #if __DARWIN_64_BIT_INO_T
  	dirp->dd_td->seekoff = lp->loc_seek;
  #else /* !__DARWIN_64_BIT_INO_T */
  	dirp->dd_seek = lp->loc_seek;
  #endif /* __DARWIN_64_BIT_INO_T */
  	dirp->dd_loc = 0;
  	while (dirp->dd_loc < lp->loc_loc) {
  		dp = _readdir_unlocked(dirp, 0);
  		if (dp == NULL)
  			break;
  	}
  found:;
  #ifdef SINGLEUSE
  	LIST_REMOVE(lp, loc_lqe);
  	free((caddr_t)lp);
  #endif
  }
  
  #ifndef BUILDING_VARIANT
  /*
   * 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);
  }
  #endif /* !BUILDING_VARIANT */
  