gen/opendir-fbsd.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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)opendir.c   8.8 (Berkeley) 5/1/95";
  36 #endif /* LIBC_SCCS and not lint */
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/gen/opendir.c,v 1.22 2004/08/14 17:46:10 stefanf Exp $");
  39
  40 #include "namespace.h"
  41 #include <sys/param.h>
  42 #include <sys/mount.h>
  43 #include <sys/stat.h>
  44
  45 #include <dirent.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <unistd.h>
  51 #include <pthread.h>
  52 #include "un-namespace.h"
  53
  54 #include "telldir.h"
  55 /*
  56  * Open a directory.
  57  */
  58 DIR *
  59 opendir(name)
  60         const char *name;
  61 {
  62
  63         return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
  64 }
  65
  66 DIR *
  67 __opendir2(name, flags)
  68         const char *name;
  69         int flags;
  70 {
  71         DIR *dirp;
  72         int fd;
  73         int incr;
  74         int saved_errno;
  75         int unionstack;
  76
  77         /*
  78          * Use O_DIRECTORY to only open directories (because opening of
  79          * special files may be harmful).  errno is set to ENOTDIR if
  80          * not a directory.
  81          */
  82         if ((fd = _open(name, O_RDONLY | O_NONBLOCK | O_DIRECTORY)) == -1)
  83                 return (NULL);
  84         dirp = NULL;
  85         if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
  86             (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
  87                 goto fail;
  88
  89         dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
  90         LIST_INIT(&dirp->dd_td->td_locq);
  91         dirp->dd_td->td_loccnt = 0;
  92
  93         /*
  94          * Use the system page size if that is a multiple of DIRBLKSIZ.
  95          * Hopefully this can be a big win someday by allowing page
  96          * trades to user space to be done by _getdirentries().
  97          */
  98         incr = getpagesize();
  99         if ((incr % DIRBLKSIZ) != 0)
 100                 incr = DIRBLKSIZ;
 101
 102         /*
 103          * Determine whether this directory is the top of a union stack.
 104          */
 105         if (flags & DTF_NODUP) {
 106                 struct statfs sfb;
 107
 108                 if (_fstatfs(fd, &sfb) < 0)
 109                         goto fail;
 110                 unionstack = !strcmp(sfb.f_fstypename, "unionfs")
 111                     || (sfb.f_flags & MNT_UNION);
 112         } else {
 113                 unionstack = 0;
 114         }
 115
 116         if (unionstack) {
 117                 int len = 0;
 118                 int space = 0;
 119                 char *buf = 0;
 120                 char *ddptr = 0;
 121                 char *ddeptr;
 122                 int n;
 123                 struct dirent **dpv;
 124
 125                 /*
 126                  * The strategy here is to read all the directory
 127                  * entries into a buffer, sort the buffer, and
 128                  * remove duplicate entries by setting the inode
 129                  * number to zero.
 130                  */
 131
 132                 do {
 133                         /*
 134                          * Always make at least DIRBLKSIZ bytes
 135                          * available to _getdirentries
 136                          */
 137                         if (space < DIRBLKSIZ) {
 138                                 space += incr;
 139                                 len += incr;
 140                                 buf = reallocf(buf, len);
 141                                 if (buf == NULL)
 142                                         goto fail;
 143                                 ddptr = buf + (len - space);
 144                         }
 145
 146 #if __DARWIN_64_BIT_INO_T
 147                         n = __getdirentries64(fd, ddptr, space, &dirp->dd_td->seekoff);
 148 #else /* !__DARWIN_64_BIT_INO_T */
 149                         n = _getdirentries(fd, ddptr, space, &dirp->dd_seek);
 150 #endif /* __DARWIN_64_BIT_INO_T */
 151                         if (n > 0) {
 152                                 ddptr += n;
 153                                 space -= n;
 154                         }
 155                 } while (n > 0);
 156
 157                 ddeptr = ddptr;
 158                 flags |= __DTF_READALL;
 159
 160                 /*
 161                  * Re-open the directory.
 162                  * This has the effect of rewinding back to the
 163                  * top of the union stack and is needed by
 164                  * programs which plan to fchdir to a descriptor
 165                  * which has also been read -- see fts.c.
 166                  */
 167                 if (flags & DTF_REWIND) {
 168                         (void)_close(fd);
 169                         if ((fd = _open(name, O_RDONLY)) == -1) {
 170                                 saved_errno = errno;
 171                                 free(buf);
 172                                 free(dirp);
 173                                 errno = saved_errno;
 174                                 return (NULL);
 175                         }
 176                 }
 177
 178                 /*
 179                  * There is now a buffer full of (possibly) duplicate
 180                  * names.
 181                  */
 182                 dirp->dd_buf = buf;
 183
 184                 /*
 185                  * Go round this loop twice...
 186                  *
 187                  * Scan through the buffer, counting entries.
 188                  * On the second pass, save pointers to each one.
 189                  * Then sort the pointers and remove duplicate names.
 190                  */
 191                 for (dpv = 0;;) {
 192                         n = 0;
 193                         ddptr = buf;
 194                         while (ddptr < ddeptr) {
 195                                 struct dirent *dp;
 196
 197                                 dp = (struct dirent *) ddptr;
 198                                 if ((long)dp & 03L)
 199                                         break;
 200                                 if ((dp->d_reclen <= 0) ||
 201                                     (dp->d_reclen > (ddeptr + 1 - ddptr)))
 202                                         break;
 203                                 ddptr += dp->d_reclen;
 204                                 if (dp->d_fileno) {
 205                                         if (dpv)
 206                                                 dpv[n] = dp;
 207                                         n++;
 208                                 }
 209                         }
 210
 211                         if (dpv) {
 212                                 struct dirent *xp;
 213
 214                                 /*
 215                                  * This sort must be stable.
 216                                  */
 217                                 mergesort(dpv, n, sizeof(*dpv), alphasort);
 218
 219                                 dpv[n] = NULL;
 220                                 xp = NULL;
 221
 222                                 /*
 223                                  * Scan through the buffer in sort order,
 224                                  * zapping the inode number of any
 225                                  * duplicate names.
 226                                  */
 227                                 for (n = 0; dpv[n]; n++) {
 228                                         struct dirent *dp = dpv[n];
 229
 230                                         if ((xp == NULL) ||
 231                                             strcmp(dp->d_name, xp->d_name)) {
 232                                                 xp = dp;
 233                                         } else {
 234                                                 dp->d_fileno = 0;
 235                                         }
 236                                         if (dp->d_type == DT_WHT &&
 237                                             (flags & DTF_HIDEW))
 238                                                 dp->d_fileno = 0;
 239                                 }
 240
 241                                 free(dpv);
 242                                 break;
 243                         } else {
 244                                 dpv = malloc((n+1) * sizeof(struct dirent *));
 245                                 if (dpv == NULL)
 246                                         break;
 247                         }
 248                 }
 249
 250                 dirp->dd_len = len;
 251                 dirp->dd_size = ddptr - dirp->dd_buf;
 252         } else {
 253                 dirp->dd_len = incr;
 254                 dirp->dd_size = 0;
 255                 dirp->dd_buf = malloc(dirp->dd_len);
 256                 if (dirp->dd_buf == NULL)
 257                         goto fail;
 258 #if __DARWIN_64_BIT_INO_T
 259                 dirp->dd_td->seekoff = 0;
 260 #else /* !__DARWIN_64_BIT_INO_T */
 261                 dirp->dd_seek = 0;
 262 #endif /* __DARWIN_64_BIT_INO_T */
 263                 flags &= ~DTF_REWIND;
 264         }
 265
 266         dirp->dd_loc = 0;
 267         dirp->dd_fd = fd;
 268         dirp->dd_flags = flags;
 269         dirp->dd_lock = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 270
 271         /*
 272          * Set up seek point for rewinddir.
 273          */
 274         dirp->dd_rewind = telldir(dirp);
 275
 276         return (dirp);
 277
 278 fail:
 279         saved_errno = errno;
 280         free(dirp);
 281         (void)_close(fd);
 282         errno = saved_errno;
 283         return (NULL);
 284 }