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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)telldir.c   8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/gen/telldir.c,v 1.11 2008/05/05 14:05:23 kib Exp $");
  35
  36 #include "namespace.h"
  37 #include <sys/param.h>
  38 #include <sys/queue.h>
  39 #include <dirent.h>
  40 #include <pthread.h>
  41 #include <stdlib.h>
  42 #include <unistd.h>
  43 #include "un-namespace.h"
  44
  45 #include "libc_private.h"
  46 #include "telldir.h"
  47
  48 /*
  49  * The option SINGLEUSE may be defined to say that a telldir
  50  * cookie may be used only once before it is freed. This option
  51  * is used to avoid having memory usage grow without bound.
  52  */
  53 #define SINGLEUSE
  54
  55 /*
  56  * return a pointer into a directory
  57  */
  58 long
  59 telldir(dirp)
  60         DIR *dirp;
  61 {
  62         struct ddloc *lp;
  63
  64         if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
  65                 return (-1);
  66         if (__isthreaded)
  67                 _pthread_mutex_lock(&dirp->dd_lock);
  68         lp->loc_index = dirp->dd_td->td_loccnt++;
  69         lp->loc_seek = dirp->dd_seek;
  70         lp->loc_loc = dirp->dd_loc;
  71         LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
  72         if (__isthreaded)
  73                 _pthread_mutex_unlock(&dirp->dd_lock);
  74         return (lp->loc_index);
  75 }
  76
  77 /*
  78  * seek to an entry in a directory.
  79  * Only values returned by "telldir" should be passed to seekdir.
  80  */
  81 void
  82 _seekdir(dirp, loc)
  83         DIR *dirp;
  84         long loc;
  85 {
  86         struct ddloc *lp;
  87         struct dirent *dp;
  88
  89         LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
  90                 if (lp->loc_index == loc)
  91                         break;
  92         }
  93         if (lp == NULL)
  94                 return;
  95         if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
  96                 goto found;
  97         (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
  98         dirp->dd_seek = lp->loc_seek;
  99         dirp->dd_loc = 0;
 100         while (dirp->dd_loc < lp->loc_loc) {
 101                 dp = _readdir_unlocked(dirp, 0);
 102                 if (dp == NULL)
 103                         break;
 104         }
 105 found:
 106 #ifdef SINGLEUSE
 107         LIST_REMOVE(lp, loc_lqe);
 108         free((caddr_t)lp);
 109 #endif
 110 }
 111
 112 /*
 113  * Reclaim memory for telldir cookies which weren't used.
 114  */
 115 void
 116 _reclaim_telldir(dirp)
 117         DIR *dirp;
 118 {
 119         struct ddloc *lp;
 120         struct ddloc *templp;
 121
 122         lp = LIST_FIRST(&dirp->dd_td->td_locq);
 123         while (lp != NULL) {
 124                 templp = lp;
 125                 lp = LIST_NEXT(lp, loc_lqe);
 126                 free(templp);
 127         }
 128         LIST_INIT(&dirp->dd_td->td_locq);
 129 }