gen/FreeBSD/opendir.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[] = "@(#)opendir.c   8.8 (Berkeley) 5/1/95";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/gen/opendir.c,v 1.24 2008/04/16 18:40:52 delphij Exp $");
  35
  36 #include "namespace.h"
  37 #include <sys/param.h>
  38 #include <sys/mount.h>
  39 #include <sys/stat.h>
  40
  41 #include <dirent.h>
  42 #include <errno.h>
  43 #include <fcntl.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <unistd.h>
  47 #include <pthread.h>
  48 #include "un-namespace.h"
  49
  50 #include "telldir.h"
  51 /*
  52  * Open a directory.
  53  */
  54 DIR *
  55 opendir(const char *name)
  56 {
  57
  58         return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
  59 }
  60
  61 DIR *
  62 __opendir2(const char *name, int flags)
  63 {
  64         DIR *dirp;
  65         int fd;
  66         int incr;
  67         int saved_errno;
  68         int unionstack;
  69
  70         /*
  71          * Use O_DIRECTORY to only open directories (because opening of
  72          * special files may be harmful).  errno is set to ENOTDIR if
  73          * not a directory.
  74          */
  75         if ((fd = _open(name, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1)
  76                 return (NULL);
  77         dirp = malloc(sizeof(DIR) + sizeof(struct _telldir));
  78         if (dirp == NULL)
  79                 goto fail;
  80
  81         dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
  82         LIST_INIT(&dirp->dd_td->td_locq);
  83         dirp->dd_td->td_loccnt = 0;
  84
  85         /*
  86          * Use the system page size if that is a multiple of DIRBLKSIZ.
  87          * Hopefully this can be a big win someday by allowing page
  88          * trades to user space to be done by _getdirentries().
  89          */
  90         incr = getpagesize();
  91         if ((incr % DIRBLKSIZ) != 0)
  92                 incr = DIRBLKSIZ;
  93
  94         /*
  95          * Determine whether this directory is the top of a union stack.
  96          */
  97         if (flags & DTF_NODUP) {
  98                 struct statfs sfb;
  99
 100                 if (_fstatfs(fd, &sfb) < 0)
 101                         goto fail;
 102                 unionstack = (sfb.f_flags & MNT_UNION);
 103         } else {
 104                 unionstack = 0;
 105         }
 106
 107         if (unionstack) {
 108                 int len = 0;
 109                 int space = 0;
 110                 char *buf = 0;
 111                 char *ddptr = 0;
 112                 char *ddeptr;
 113                 int n;
 114                 struct dirent **dpv;
 115
 116                 /*
 117                  * The strategy here is to read all the directory
 118                  * entries into a buffer, sort the buffer, and
 119                  * remove duplicate entries by setting the inode
 120                  * number to zero.
 121                  */
 122
 123                 do {
 124                         /*
 125                          * Always make at least DIRBLKSIZ bytes
 126                          * available to _getdirentries
 127                          */
 128                         if (space < DIRBLKSIZ) {
 129                                 space += incr;
 130                                 len += incr;
 131                                 buf = reallocf(buf, len);
 132                                 if (buf == NULL)
 133                                         goto fail;
 134                                 ddptr = buf + (len - space);
 135                         }
 136
 137 #if __DARWIN_64_BIT_INO_T
 138                         n = __getdirentries64(fd, ddptr, space, &dirp->dd_td->seekoff);
 139 #else /* !__DARWIN_64_BIT_INO_T */
 140                         n = _getdirentries(fd, ddptr, space, &dirp->dd_seek);
 141 #endif /* __DARWIN_64_BIT_INO_T */
 142                         if (n > 0) {
 143                                 ddptr += n;
 144                                 space -= n;
 145                         }
 146                 } while (n > 0);
 147
 148                 ddeptr = ddptr;
 149                 flags |= __DTF_READALL;
 150
 151                 /*
 152                  * Re-open the directory.
 153                  * This has the effect of rewinding back to the
 154                  * top of the union stack and is needed by
 155                  * programs which plan to fchdir to a descriptor
 156                  * which has also been read -- see fts.c.
 157                  */
 158                 if (flags & DTF_REWIND) {
 159                         (void)_close(fd);
 160                         if ((fd = _open(name, O_RDONLY)) == -1) {
 161                                 saved_errno = errno;
 162                                 free(buf);
 163                                 free(dirp);
 164                                 errno = saved_errno;
 165                                 return (NULL);
 166                         }
 167                 }
 168
 169                 /*
 170                  * There is now a buffer full of (possibly) duplicate
 171                  * names.
 172                  */
 173                 dirp->dd_buf = buf;
 174
 175                 /*
 176                  * Go round this loop twice...
 177                  *
 178                  * Scan through the buffer, counting entries.
 179                  * On the second pass, save pointers to each one.
 180                  * Then sort the pointers and remove duplicate names.
 181                  */
 182                 for (dpv = 0;;) {
 183                         n = 0;
 184                         ddptr = buf;
 185                         while (ddptr < ddeptr) {
 186                                 struct dirent *dp;
 187
 188                                 dp = (struct dirent *) ddptr;
 189                                 if ((long)dp & 03L)
 190                                         break;
 191                                 if ((dp->d_reclen <= 0) ||
 192                                     (dp->d_reclen > (ddeptr + 1 - ddptr)))
 193                                         break;
 194                                 ddptr += dp->d_reclen;
 195                                 if (dp->d_fileno) {
 196                                         if (dpv)
 197                                                 dpv[n] = dp;
 198                                         n++;
 199                                 }
 200                         }
 201
 202                         if (dpv) {
 203                                 struct dirent *xp;
 204
 205                                 /*
 206                                  * This sort must be stable.
 207                                  */
 208                                 mergesort(dpv, n, sizeof(*dpv), alphasort);
 209
 210                                 dpv[n] = NULL;
 211                                 xp = NULL;
 212
 213                                 /*
 214                                  * Scan through the buffer in sort order,
 215                                  * zapping the inode number of any
 216                                  * duplicate names.
 217                                  */
 218                                 for (n = 0; dpv[n]; n++) {
 219                                         struct dirent *dp = dpv[n];
 220
 221                                         if ((xp == NULL) ||
 222                                             strcmp(dp->d_name, xp->d_name)) {
 223                                                 xp = dp;
 224                                         } else {
 225                                                 dp->d_fileno = 0;
 226                                         }
 227                                         if (dp->d_type == DT_WHT &&
 228                                             (flags & DTF_HIDEW))
 229                                                 dp->d_fileno = 0;
 230                                 }
 231
 232                                 free(dpv);
 233                                 break;
 234                         } else {
 235                                 dpv = malloc((n+1) * sizeof(struct dirent *));
 236                                 if (dpv == NULL)
 237                                         break;
 238                         }
 239                 }
 240
 241                 dirp->dd_len = len;
 242                 dirp->dd_size = ddptr - dirp->dd_buf;
 243         } else {
 244                 dirp->dd_len = incr;
 245                 dirp->dd_size = 0;
 246                 dirp->dd_buf = malloc(dirp->dd_len);
 247                 if (dirp->dd_buf == NULL)
 248                         goto fail;
 249 #if __DARWIN_64_BIT_INO_T
 250                 dirp->dd_td->seekoff = 0;
 251 #else /* !__DARWIN_64_BIT_INO_T */
 252                 dirp->dd_seek = 0;
 253 #endif /* __DARWIN_64_BIT_INO_T */
 254                 flags &= ~DTF_REWIND;
 255         }
 256
 257         dirp->dd_loc = 0;
 258         dirp->dd_fd = fd;
 259         dirp->dd_flags = flags;
 260         dirp->dd_lock = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 261
 262         /*
 263          * Set up seek point for rewinddir.
 264          */
 265         dirp->dd_rewind = telldir(dirp);
 266
 267         return (dirp);
 268
 269 fail:
 270         saved_errno = errno;
 271         free(dirp);
 272         (void)_close(fd);
 273         errno = saved_errno;
 274         return (NULL);
 275 }