gen/FreeBSD/readdir.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[] = "@(#)readdir.c   8.3 (Berkeley) 9/29/94";
  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 <dirent.h>
  39 #include <errno.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43 #include <pthread.h>
  44 #include "un-namespace.h"
  45
  46 #include "libc_private.h"
  47 #include "telldir.h"
  48
  49 /*
  50  * get next entry in a directory.
  51  */
  52 struct dirent *
  53 _readdir_unlocked(DIR *dirp, int skip)
  54 {
  55         struct dirent *dp;
  56         long initial_seek;
  57         long initial_loc = 0;
  58
  59         for (;;) {
  60                 if (dirp->dd_loc >= dirp->dd_size) {
  61                         if (dirp->dd_flags & (__DTF_READALL | __DTF_ATEND))
  62                                 return (NULL);
  63                         initial_loc = dirp->dd_loc;
  64                         dirp->dd_flags &= ~__DTF_SKIPREAD;
  65                         dirp->dd_loc = 0;
  66                 }
  67                 if (dirp->dd_loc == 0 &&
  68                     !(dirp->dd_flags & (__DTF_READALL | __DTF_ATEND | __DTF_SKIPREAD))) {
  69                         if (dirp->dd_len == READDIR_INITIAL_SIZE) {
  70                                 /*
  71                                  * If we need to read more, and we still have the original size,
  72                                  * then grow the internal buffer to a large size to amortize
  73                                  * the cost of __getdirentries64 calls.
  74                                  */
  75                                 int len = READDIR_LARGE_SIZE;
  76                                 char *buf = malloc(len);
  77                                 if (buf) {
  78                                         free(dirp->dd_buf);
  79                                         dirp->dd_buf = buf;
  80                                         dirp->dd_len = len;
  81                                 }
  82                         }
  83 #if __DARWIN_64_BIT_INO_T
  84                         /*
  85                          * sufficiently recent kernels when the buffer is large enough,
  86                          * will use the last bytes of the buffer to return status.
  87                          *
  88                          * To support older kernels:
  89                          * - make sure it's 0 initialized
  90                          * - make sure it's past `dd_size` before reading it
  91                          */
  92                         getdirentries64_flags_t *gdeflags =
  93                             (getdirentries64_flags_t *)(dirp->dd_buf + dirp->dd_len -
  94                             sizeof(getdirentries64_flags_t));
  95                         *gdeflags = 0;
  96                         initial_seek = dirp->dd_td->seekoff;
  97                         dirp->dd_size = (long)__getdirentries64(dirp->dd_fd,
  98                             dirp->dd_buf, dirp->dd_len, &dirp->dd_td->seekoff);
  99                         if (dirp->dd_size >= 0 &&
 100                             dirp->dd_size <= dirp->dd_len - sizeof(getdirentries64_flags_t)) {
 101                                 if (*gdeflags & GETDIRENTRIES64_EOF) {
 102                                         dirp->dd_flags |= __DTF_ATEND;
 103                                 }
 104                         }
 105 #else /* !__DARWIN_64_BIT_INO_T */
 106                         initial_seek = dirp->dd_seek;
 107                         dirp->dd_size = _getdirentries(dirp->dd_fd,
 108                             dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
 109 #endif /* __DARWIN_64_BIT_INO_T */
 110                         if (dirp->dd_size <= 0)
 111                                 return (NULL);
 112                         _fixtelldir(dirp, initial_seek, initial_loc);
 113                 }
 114                 dirp->dd_flags &= ~__DTF_SKIPREAD;
 115                 dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
 116                 if ((long)dp & 03L)     /* bogus pointer check */
 117                         return (NULL);
 118                 if (dp->d_reclen <= 0 ||
 119                     dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
 120                         return (NULL);
 121                 dirp->dd_loc += dp->d_reclen;
 122                 if (dp->d_ino == 0 && skip)
 123                         continue;
 124                 if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
 125                         continue;
 126                 return (dp);
 127         }
 128 }
 129
 130 struct dirent *
 131 readdir(DIR *dirp)
 132 {
 133         struct dirent   *dp;
 134
 135         if (__isthreaded) {
 136                 _pthread_mutex_lock(&dirp->dd_lock);
 137                 dp = _readdir_unlocked(dirp, 1);
 138                 _pthread_mutex_unlock(&dirp->dd_lock);
 139         }
 140         else
 141                 dp = _readdir_unlocked(dirp, 1);
 142         return (dp);
 143 }
 144
 145 int
 146 readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
 147 {
 148         struct dirent *dp;
 149         int saved_errno;
 150
 151         saved_errno = errno;
 152         errno = 0;
 153         if (__isthreaded) {
 154                 _pthread_mutex_lock(&dirp->dd_lock);
 155                 if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
 156                         memcpy(entry, dp, _GENERIC_DIRSIZ(dp));
 157                 _pthread_mutex_unlock(&dirp->dd_lock);
 158         }
 159         else if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
 160                 memcpy(entry, dp, _GENERIC_DIRSIZ(dp));
 161
 162         if (errno != 0) {
 163                 if (dp == NULL)
 164                         return (errno);
 165         } else
 166                 errno = saved_errno;
 167
 168         if (dp != NULL)
 169                 *result = entry;
 170         else
 171                 *result = NULL;
 172
 173         return (0);
 174 }