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("$FreeBSD$");
  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 static DIR * __opendir_common(int, const char *, int);
  53
  54 /*
  55  * Open a directory.
  56  */
  57 DIR *
  58 opendir(const char *name)
  59 {
  60
  61         return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
  62 }
  63
  64 /*
  65  * Open a directory with existing file descriptor.
  66  */
  67 DIR *
  68 fdopendir(int fd)
  69 {
  70         struct stat statb;
  71
  72         /* Check that fd is associated with a directory. */
  73         if (_fstat(fd, &statb) != 0)
  74                 return (NULL);
  75         if (!S_ISDIR(statb.st_mode)) {
  76                 errno = ENOTDIR;
  77                 return (NULL);
  78         }
  79         if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
  80                 return (NULL);
  81         return (__opendir_common(fd, NULL, DTF_HIDEW|DTF_NODUP));
  82 }
  83
  84 DIR *
  85 __opendir2(const char *name, int flags)
  86 {
  87         int fd;
  88
  89         if ((fd = _open(name,
  90             O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1)
  91                 return (NULL);
  92
  93         return __opendir_common(fd, name, flags);
  94 }
  95
  96 static int
  97 opendir_compar(const void *p1, const void *p2)
  98 {
  99
 100         return (strcmp((*(const struct dirent **)p1)->d_name,
 101             (*(const struct dirent **)p2)->d_name));
 102 }
 103
 104 /*
 105  * Common routine for opendir(3), __opendir2(3) and fdopendir(3).
 106  */
 107 static DIR *
 108 __opendir_common(int fd, const char *name, int flags)
 109 {
 110         DIR *dirp;
 111         int incr;
 112         int saved_errno;
 113         int unionstack;
 114
 115         if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
 116                 return (NULL);
 117
 118         dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
 119         LIST_INIT(&dirp->dd_td->td_locq);
 120         dirp->dd_td->td_loccnt = 0;
 121
 122         /*
 123          * Use the system page size if that is a multiple of DIRBLKSIZ.
 124          * Hopefully this can be a big win someday by allowing page
 125          * trades to user space to be done by _getdirentries().
 126          */
 127         incr = getpagesize();
 128         if ((incr % DIRBLKSIZ) != 0)
 129                 incr = DIRBLKSIZ;
 130
 131         /*
 132          * Determine whether this directory is the top of a union stack.
 133          */
 134         if (flags & DTF_NODUP) {
 135                 struct statfs sfb;
 136
 137                 if (_fstatfs(fd, &sfb) < 0)
 138                         goto fail;
 139                 unionstack = !strcmp(sfb.f_fstypename, "unionfs")
 140                     || (sfb.f_flags & MNT_UNION);
 141         } else {
 142                 unionstack = 0;
 143         }
 144
 145         if (unionstack) {
 146                 int len = 0;
 147                 int space = 0;
 148                 char *buf = 0;
 149                 char *ddptr = 0;
 150                 char *ddeptr;
 151                 int n;
 152                 struct dirent **dpv;
 153
 154                 /*
 155                  * The strategy here is to read all the directory
 156                  * entries into a buffer, sort the buffer, and
 157                  * remove duplicate entries by setting the inode
 158                  * number to zero.
 159                  */
 160
 161                 do {
 162                         /*
 163                          * Always make at least DIRBLKSIZ bytes
 164                          * available to _getdirentries
 165                          */
 166                         if (space < DIRBLKSIZ) {
 167                                 space += incr;
 168                                 len += incr;
 169                                 buf = reallocf(buf, len);
 170                                 if (buf == NULL)
 171                                         goto fail;
 172                                 ddptr = buf + (len - space);
 173                         }
 174
 175 #if __DARWIN_64_BIT_INO_T
 176                         n = (int)__getdirentries64(fd, ddptr, space, &dirp->dd_td->seekoff);
 177 #else /* !__DARWIN_64_BIT_INO_T */
 178                         n = _getdirentries(fd, ddptr, space, &dirp->dd_seek);
 179 #endif /* __DARWIN_64_BIT_INO_T */
 180                         if (n > 0) {
 181                                 ddptr += n;
 182                                 space -= n;
 183                         }
 184                 } while (n > 0);
 185
 186                 ddeptr = ddptr;
 187                 flags |= __DTF_READALL;
 188
 189                 /*
 190                  * Re-open the directory.
 191                  * This has the effect of rewinding back to the
 192                  * top of the union stack and is needed by
 193                  * programs which plan to fchdir to a descriptor
 194                  * which has also been read -- see fts.c.
 195                  */
 196                 if (flags & DTF_REWIND) {
 197                         (void)_close(fd);
 198                         if ((fd = _open(name, O_RDONLY | O_DIRECTORY)) == -1) {
 199                                 saved_errno = errno;
 200                                 free(buf);
 201                                 free(dirp);
 202                                 errno = saved_errno;
 203                                 return (NULL);
 204                         }
 205                 }
 206
 207                 /*
 208                  * There is now a buffer full of (possibly) duplicate
 209                  * names.
 210                  */
 211                 dirp->dd_buf = buf;
 212
 213                 /*
 214                  * Go round this loop twice...
 215                  *
 216                  * Scan through the buffer, counting entries.
 217                  * On the second pass, save pointers to each one.
 218                  * Then sort the pointers and remove duplicate names.
 219                  */
 220                 for (dpv = 0;;) {
 221                         n = 0;
 222                         ddptr = buf;
 223                         while (ddptr < ddeptr) {
 224                                 struct dirent *dp;
 225
 226                                 dp = (struct dirent *) ddptr;
 227                                 if ((long)dp & 03L)
 228                                         break;
 229                                 if ((dp->d_reclen <= 0) ||
 230                                     (dp->d_reclen > (ddeptr + 1 - ddptr)))
 231                                         break;
 232                                 ddptr += dp->d_reclen;
 233                                 if (dp->d_fileno) {
 234                                         if (dpv)
 235                                                 dpv[n] = dp;
 236                                         n++;
 237                                 }
 238                         }
 239
 240                         if (dpv) {
 241                                 struct dirent *xp;
 242
 243                                 /*
 244                                  * This sort must be stable.
 245                                  */
 246                                 mergesort(dpv, n, sizeof(*dpv),
 247                                     opendir_compar);
 248
 249                                 dpv[n] = NULL;
 250                                 xp = NULL;
 251
 252                                 /*
 253                                  * Scan through the buffer in sort order,
 254                                  * zapping the inode number of any
 255                                  * duplicate names.
 256                                  */
 257                                 for (n = 0; dpv[n]; n++) {
 258                                         struct dirent *dp = dpv[n];
 259
 260                                         if ((xp == NULL) ||
 261                                             strcmp(dp->d_name, xp->d_name)) {
 262                                                 xp = dp;
 263                                         } else {
 264                                                 dp->d_fileno = 0;
 265                                         }
 266                                         if (dp->d_type == DT_WHT &&
 267                                             (flags & DTF_HIDEW))
 268                                                 dp->d_fileno = 0;
 269                                 }
 270
 271                                 free(dpv);
 272                                 break;
 273                         } else {
 274                                 dpv = malloc((n+1) * sizeof(struct dirent *));
 275                                 if (dpv == NULL)
 276                                         break;
 277                         }
 278                 }
 279
 280                 dirp->dd_len = len;
 281                 dirp->dd_size = ddptr - dirp->dd_buf;
 282         } else {
 283                 dirp->dd_len = incr;
 284                 dirp->dd_size = 0;
 285                 dirp->dd_buf = malloc(dirp->dd_len);
 286                 if (dirp->dd_buf == NULL)
 287                         goto fail;
 288 #if __DARWIN_64_BIT_INO_T
 289                 dirp->dd_td->seekoff = 0;
 290 #else /* !__DARWIN_64_BIT_INO_T */
 291                 dirp->dd_seek = 0;
 292 #endif /* __DARWIN_64_BIT_INO_T */
 293                 flags &= ~DTF_REWIND;
 294         }
 295
 296         dirp->dd_loc = 0;
 297         dirp->dd_fd = fd;
 298         dirp->dd_flags = flags;
 299         dirp->dd_lock = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 300
 301         /*
 302          * Set up seek point for rewinddir.
 303          */
 304         dirp->dd_rewind = telldir(dirp);
 305
 306         return (dirp);
 307
 308 fail:
 309         saved_errno = errno;
 310         free(dirp);
 311         (void)_close(fd);
 312         errno = saved_errno;
 313         return (NULL);
 314 }