gen/FreeBSD/telldir.c

   1 /*
   2  * Copyright (c) 1983, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)telldir.c   8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/gen/telldir.c,v 1.8 2002/02/01 00:57:29 obrien Exp $");
  39
  40 #include "namespace.h"
  41 #include <sys/param.h>
  42 #include <sys/queue.h>
  43 #include <dirent.h>
  44 #include <pthread.h>
  45 #include <stdlib.h>
  46 #include <unistd.h>
  47 #include "un-namespace.h"
  48
  49 #include "libc_private.h"
  50 #include "telldir.h"
  51
  52 /*
  53  * The option SINGLEUSE may be defined to say that a telldir
  54  * cookie may be used only once before it is freed. This option
  55  * is used to avoid having memory usage grow without bound.
  56  */
  57 #define SINGLEUSE
  58
  59 /*
  60  * return a pointer into a directory
  61  */
  62 long
  63 telldir(dirp)
  64         DIR *dirp;
  65 {
  66         struct ddloc *lp;
  67
  68         if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
  69                 return (-1);
  70         if (__isthreaded)
  71                 _pthread_mutex_lock((pthread_mutex_t *)&dirp->dd_lock);
  72         lp->loc_index = dirp->dd_td->td_loccnt++;
  73         lp->loc_seek = dirp->dd_seek;
  74         lp->loc_loc = dirp->dd_loc;
  75         LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
  76         if (__isthreaded)
  77                 _pthread_mutex_unlock((pthread_mutex_t *)&dirp->dd_lock);
  78         return (lp->loc_index);
  79 }
  80
  81 /*
  82  * seek to an entry in a directory.
  83  * Only values returned by "telldir" should be passed to seekdir.
  84  */
  85 void
  86 _seekdir(dirp, loc)
  87         DIR *dirp;
  88         long loc;
  89 {
  90         struct ddloc *lp;
  91         struct dirent *dp;
  92
  93         LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
  94                 if (lp->loc_index == loc)
  95                         break;
  96         }
  97         if (lp == NULL)
  98                 return;
  99         if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
 100                 goto found;
 101         (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
 102         dirp->dd_seek = lp->loc_seek;
 103         dirp->dd_loc = 0;
 104         while (dirp->dd_loc < lp->loc_loc) {
 105                 dp = _readdir_unlocked(dirp);
 106                 if (dp == NULL)
 107                         break;
 108         }
 109 found:
 110 #ifdef SINGLEUSE
 111         LIST_REMOVE(lp, loc_lqe);
 112         free((caddr_t)lp);
 113 #endif
 114 }
 115
 116 /*
 117  * Reclaim memory for telldir cookies which weren't used.
 118  */
 119 void
 120 _reclaim_telldir(dirp)
 121         DIR *dirp;
 122 {
 123         struct ddloc *lp;
 124         struct ddloc *templp;
 125
 126         lp = LIST_FIRST(&dirp->dd_td->td_locq);
 127         while (lp != NULL) {
 128                 templp = lp;
 129                 lp = LIST_NEXT(lp, loc_lqe);
 130                 free(templp);
 131         }
 132         LIST_INIT(&dirp->dd_td->td_locq);
 133 }