lib/libc/gen/readdir.c

   1 /*      $NetBSD: readdir.c,v 1.26 2012/06/25 22:32:43 abs Exp $ */
   2
   3 /*
   4  * Copyright (c) 1983, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 #if 0
  35 static char sccsid[] = "@(#)readdir.c   8.3 (Berkeley) 9/29/94";
  36 #else
  37 __RCSID("$NetBSD: readdir.c,v 1.26 2012/06/25 22:32:43 abs Exp $");
  38 #endif
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include "namespace.h"
  42 #include "reentrant.h"
  43 #include "extern.h"
  44 #include <sys/param.h>
  45
  46 #include <dirent.h>
  47 #include <errno.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50
  51 #include "dirent_private.h"
  52
  53 /*
  54  * get next entry in a directory.
  55  */
  56 struct dirent *
  57 _readdir_unlocked(DIR *dirp, int skipdeleted)
  58 {
  59         struct dirent *dp;
  60
  61         for (;;) {
  62                 if (dirp->dd_loc >= dirp->dd_size) {
  63                         if (dirp->dd_flags & __DTF_READALL)
  64                                 return (NULL);
  65                         dirp->dd_loc = 0;
  66                 }
  67                 if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
  68                         dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
  69                         dirp->dd_size = getdents(dirp->dd_fd,
  70                             dirp->dd_buf, (size_t)dirp->dd_len);
  71                         if (dirp->dd_size <= 0)
  72                                 return (NULL);
  73                 }
  74                 dp = (struct dirent *)
  75                     (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
  76                 if ((intptr_t)dp & _DIRENT_ALIGN(dp))/* bogus pointer check */
  77                         return (NULL);
  78                 /* d_reclen is unsigned; no need to compare it <= 0 */
  79                 if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
  80                         return (NULL);
  81                 dirp->dd_loc += dp->d_reclen;
  82                 if (dp->d_ino == 0 && skipdeleted)
  83                         continue;
  84 #if !defined(__minix)
  85                 if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
  86                         continue;
  87 #endif /* !defined(__minix) */
  88                 return (dp);
  89         }
  90 }
  91
  92 struct dirent *
  93 readdir(DIR *dirp)
  94 {
  95         struct dirent   *dp;
  96
  97 #ifdef _REENTRANT
  98         if (__isthreaded) {
  99                 mutex_lock((mutex_t *)dirp->dd_lock);
 100                 dp = _readdir_unlocked(dirp, 1);
 101                 mutex_unlock((mutex_t *)dirp->dd_lock);
 102         }
 103         else
 104 #endif
 105                 dp = _readdir_unlocked(dirp, 1);
 106         return (dp);
 107 }
 108
 109 int
 110 readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
 111 {
 112         struct dirent *dp;
 113         int saved_errno;
 114
 115         saved_errno = errno;
 116         errno = 0;
 117 #ifdef _REENTRANT
 118         if (__isthreaded) {
 119                 mutex_lock((mutex_t *)dirp->dd_lock);
 120                 if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
 121                         memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
 122                 mutex_unlock((mutex_t *)dirp->dd_lock);
 123         }
 124         else
 125 #endif
 126                 if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
 127                         memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
 128
 129         if (errno != 0) {
 130                 if (dp == NULL)
 131                         return (errno);
 132         } else
 133                 errno = saved_errno;
 134
 135         if (dp != NULL)
 136                 *result = entry;
 137         else
 138                 *result = NULL;
 139
 140         return (0);
 141 }