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  * 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 "un-namespace.h"
  52
  53 #include "telldir.h"
  54 /*
  55  * Open a directory.
  56  */
  57 DIR *
  58 opendir(name)
  59         const char *name;
  60 {
  61
  62         return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
  63 }
  64
  65 DIR *
  66 __opendir2(name, flags)
  67         const char *name;
  68         int flags;
  69 {
  70         DIR *dirp;
  71         int fd;
  72         int incr;
  73         int saved_errno;
  74         int unionstack;
  75         struct stat statb;
  76
  77         /*
  78          * stat() before _open() because opening of special files may be
  79          * harmful.  _fstat() after open because the file may have changed.
  80          */
  81         if (stat(name, &statb) != 0)
  82                 return (NULL);
  83         if (!S_ISDIR(statb.st_mode)) {
  84                 errno = ENOTDIR;
  85                 return (NULL);
  86         }
  87         if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1)
  88                 return (NULL);
  89         dirp = NULL;
  90         if (_fstat(fd, &statb) != 0)
  91                 goto fail;
  92         if (!S_ISDIR(statb.st_mode)) {
  93                 errno = ENOTDIR;
  94                 goto fail;
  95         }
  96         if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
  97             (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
  98                 goto fail;
  99
 100         dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
 101         LIST_INIT(&dirp->dd_td->td_locq);
 102         dirp->dd_td->td_loccnt = 0;
 103
 104         /*
 105          * Use the system page size if that is a multiple of DIRBLKSIZ.
 106          * Hopefully this can be a big win someday by allowing page
 107          * trades to user space to be done by _getdirentries().
 108          */
 109         incr = getpagesize();
 110         if ((incr % DIRBLKSIZ) != 0)
 111                 incr = DIRBLKSIZ;
 112
 113         /*
 114          * Determine whether this directory is the top of a union stack.
 115          */
 116         if (flags & DTF_NODUP) {
 117                 struct statfs sfb;
 118
 119                 if (_fstatfs(fd, &sfb) < 0)
 120                         goto fail;
 121                 unionstack = !strcmp(sfb.f_fstypename, "unionfs")
 122                     || (sfb.f_flags & MNT_UNION);
 123         } else {
 124                 unionstack = 0;
 125         }
 126
 127         if (unionstack) {
 128                 int len = 0;
 129                 int space = 0;
 130                 char *buf = 0;
 131                 char *ddptr = 0;
 132                 char *ddeptr;
 133                 int n;
 134                 struct dirent **dpv;
 135
 136                 /*
 137                  * The strategy here is to read all the directory
 138                  * entries into a buffer, sort the buffer, and
 139                  * remove duplicate entries by setting the inode
 140                  * number to zero.
 141                  */
 142
 143                 do {
 144                         /*
 145                          * Always make at least DIRBLKSIZ bytes
 146                          * available to _getdirentries
 147                          */
 148                         if (space < DIRBLKSIZ) {
 149                                 space += incr;
 150                                 len += incr;
 151                                 buf = reallocf(buf, len);
 152                                 if (buf == NULL)
 153                                         goto fail;
 154                                 ddptr = buf + (len - space);
 155                         }
 156
 157                         n = _getdirentries(fd, ddptr, space, &dirp->dd_seek);
 158                         if (n > 0) {
 159                                 ddptr += n;
 160                                 space -= n;
 161                         }
 162                 } while (n > 0);
 163
 164                 ddeptr = ddptr;
 165                 flags |= __DTF_READALL;
 166
 167                 /*
 168                  * Re-open the directory.
 169                  * This has the effect of rewinding back to the
 170                  * top of the union stack and is needed by
 171                  * programs which plan to fchdir to a descriptor
 172                  * which has also been read -- see fts.c.
 173                  */
 174                 if (flags & DTF_REWIND) {
 175                         (void)_close(fd);
 176                         if ((fd = _open(name, O_RDONLY)) == -1) {
 177                                 saved_errno = errno;
 178                                 free(buf);
 179                                 free(dirp);
 180                                 errno = saved_errno;
 181                                 return (NULL);
 182                         }
 183                 }
 184
 185                 /*
 186                  * There is now a buffer full of (possibly) duplicate
 187                  * names.
 188                  */
 189                 dirp->dd_buf = buf;
 190
 191                 /*
 192                  * Go round this loop twice...
 193                  *
 194                  * Scan through the buffer, counting entries.
 195                  * On the second pass, save pointers to each one.
 196                  * Then sort the pointers and remove duplicate names.
 197                  */
 198                 for (dpv = 0;;) {
 199                         n = 0;
 200                         ddptr = buf;
 201                         while (ddptr < ddeptr) {
 202                                 struct dirent *dp;
 203
 204                                 dp = (struct dirent *) ddptr;
 205                                 if ((long)dp & 03L)
 206                                         break;
 207                                 if ((dp->d_reclen <= 0) ||
 208                                     (dp->d_reclen > (ddeptr + 1 - ddptr)))
 209                                         break;
 210                                 ddptr += dp->d_reclen;
 211                                 if (dp->d_fileno) {
 212                                         if (dpv)
 213                                                 dpv[n] = dp;
 214                                         n++;
 215                                 }
 216                         }
 217
 218                         if (dpv) {
 219                                 struct dirent *xp;
 220
 221                                 /*
 222                                  * This sort must be stable.
 223                                  */
 224                                 mergesort(dpv, n, sizeof(*dpv), alphasort);
 225
 226                                 dpv[n] = NULL;
 227                                 xp = NULL;
 228
 229                                 /*
 230                                  * Scan through the buffer in sort order,
 231                                  * zapping the inode number of any
 232                                  * duplicate names.
 233                                  */
 234                                 for (n = 0; dpv[n]; n++) {
 235                                         struct dirent *dp = dpv[n];
 236
 237                                         if ((xp == NULL) ||
 238                                             strcmp(dp->d_name, xp->d_name)) {
 239                                                 xp = dp;
 240                                         } else {
 241                                                 dp->d_fileno = 0;
 242                                         }
 243                                         if (dp->d_type == DT_WHT &&
 244                                             (flags & DTF_HIDEW))
 245                                                 dp->d_fileno = 0;
 246                                 }
 247
 248                                 free(dpv);
 249                                 break;
 250                         } else {
 251                                 dpv = malloc((n+1) * sizeof(struct dirent *));
 252                                 if (dpv == NULL)
 253                                         break;
 254                         }
 255                 }
 256
 257                 dirp->dd_len = len;
 258                 dirp->dd_size = ddptr - dirp->dd_buf;
 259         } else {
 260                 dirp->dd_len = incr;
 261                 dirp->dd_size = 0;
 262                 dirp->dd_buf = malloc(dirp->dd_len);
 263                 if (dirp->dd_buf == NULL)
 264                         goto fail;
 265                 dirp->dd_seek = 0;
 266                 flags &= ~DTF_REWIND;
 267         }
 268
 269         dirp->dd_loc = 0;
 270         dirp->dd_fd = fd;
 271         dirp->dd_flags = flags;
 272         dirp->dd_lock = NULL;
 273
 274         /*
 275          * Set up seek point for rewinddir.
 276          */
 277         dirp->dd_rewind = telldir(dirp);
 278
 279         return (dirp);
 280
 281 fail:
 282         saved_errno = errno;
 283         free(dirp);
 284         (void)_close(fd);
 285         errno = saved_errno;
 286         return (NULL);
 287 }