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("$FreeBSD$");
  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  * return a pointer into a directory
  50  */
  51 long
  52 telldir(DIR *dirp)
  53 {
  54         struct ddloc *lp;
  55         long idx;
  56
  57         if (__isthreaded)
  58                 _pthread_mutex_lock(&dirp->dd_lock);
  59         LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
  60 #if __DARWIN_64_BIT_INO_T
  61                 if (lp->loc_seek == dirp->dd_td->seekoff &&
  62 #else /* !__DARWIN_64_BIT_INO_T */
  63                 if (lp->loc_seek == dirp->dd_seek &&
  64 #endif /* __DARWIN_64_BIT_INO_T */
  65                     lp->loc_loc == dirp->dd_loc)
  66                         break;
  67         }
  68         if (lp == NULL) {
  69                 lp = malloc(sizeof(struct ddloc));
  70                 if (lp == NULL) {
  71                         if (__isthreaded)
  72                                 _pthread_mutex_unlock(&dirp->dd_lock);
  73                         return (-1);
  74                 }
  75                 lp->loc_index = dirp->dd_td->td_loccnt++;
  76 #if __DARWIN_64_BIT_INO_T
  77                 lp->loc_seek = dirp->dd_td->seekoff;
  78 #else /* !__DARWIN_64_BIT_INO_T */
  79                 lp->loc_seek = dirp->dd_seek;
  80 #endif /* __DARWIN_64_BIT_INO_T */
  81                 lp->loc_loc = dirp->dd_loc;
  82                 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
  83         }
  84         idx = lp->loc_index;
  85         if (__isthreaded)
  86                 _pthread_mutex_unlock(&dirp->dd_lock);
  87         return (idx);
  88 }
  89
  90 /*
  91  * seek to an entry in a directory.
  92  * Only values returned by "telldir" should be passed to seekdir.
  93  */
  94 void
  95 _seekdir(DIR *dirp, long loc)
  96 {
  97         struct ddloc *lp;
  98         struct dirent *dp;
  99
 100         LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
 101                 if (lp->loc_index == loc)
 102                         break;
 103         }
 104         if (lp == NULL)
 105                 return;
 106 #if __DARWIN_64_BIT_INO_T
 107         if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_td->seekoff)
 108 #else /* !__DARWIN_64_BIT_INO_T */
 109         if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
 110 #endif /* __DARWIN_64_BIT_INO_T */
 111                 return;
 112
 113         /* If it's within the same chunk of data, don't bother reloading. */
 114 #if __DARWIN_64_BIT_INO_T
 115         if (lp->loc_seek == dirp->dd_td->seekoff) {
 116 #else /* !__DARWIN_64_BIT_INO_T */
 117         if (lp->loc_seek == dirp->dd_seek) {
 118 #endif /* __DARWIN_64_BIT_INO_T */
 119                 /*
 120                  * If we go back to 0 don't make the next readdir
 121                  * trigger a call to getdirentries().
 122                  */
 123                 if (lp->loc_loc == 0)
 124                         dirp->dd_flags |= __DTF_SKIPREAD;
 125                 dirp->dd_loc = lp->loc_loc;
 126                 return;
 127         }
 128         (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
 129 #if __DARWIN_64_BIT_INO_T
 130         dirp->dd_td->seekoff = lp->loc_seek;
 131 #else /* !__DARWIN_64_BIT_INO_T */
 132         dirp->dd_seek = lp->loc_seek;
 133 #endif /* __DARWIN_64_BIT_INO_T */
 134         dirp->dd_loc = 0;
 135         dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */
 136         while (dirp->dd_loc < lp->loc_loc) {
 137                 dp = _readdir_unlocked(dirp, 0);
 138                 if (dp == NULL)
 139                         break;
 140         }
 141 }
 142
 143 /*
 144  * After readdir returns the last entry in a block, a call to telldir
 145  * returns a location that is after the end of that last entry.
 146  * However, that location doesn't refer to a valid directory entry.
 147  * Ideally, the call to telldir would return a location that refers to
 148  * the first entry in the next block.  That location is not known
 149  * until the next block is read, so readdir calls this function after
 150  * fetching a new block to fix any such telldir locations.
 151  */
 152 void
 153 _fixtelldir(DIR *dirp, long oldseek, long oldloc)
 154 {
 155         struct ddloc *lp;
 156
 157         lp = LIST_FIRST(&dirp->dd_td->td_locq);
 158         if (lp != NULL) {
 159                 if (lp->loc_loc == oldloc &&
 160                     lp->loc_seek == oldseek) {
 161 #if __DARWIN_64_BIT_INO_T
 162                         lp->loc_seek = dirp->dd_td->seekoff;
 163 #else /* !__DARWIN_64_BIT_INO_T */
 164                         lp->loc_seek = dirp->dd_seek;
 165 #endif /* __DARWIN_64_BIT_INO_T */
 166                         lp->loc_loc = dirp->dd_loc;
 167                 }
 168         }
 169 }
 170
 171 #ifndef BUILDING_VARIANT
 172 /*
 173  * Reclaim memory for telldir cookies which weren't used.
 174  */
 175 void
 176 _reclaim_telldir(DIR *dirp)
 177 {
 178         struct ddloc *lp;
 179         struct ddloc *templp;
 180
 181         lp = LIST_FIRST(&dirp->dd_td->td_locq);
 182         while (lp != NULL) {
 183                 templp = lp;
 184                 lp = LIST_NEXT(lp, loc_lqe);
 185                 free(templp);
 186         }
 187         LIST_INIT(&dirp->dd_td->td_locq);
 188 }
 189 #endif