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, int, bool);
  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         /* Make sure CLOEXEC is set on the fd */
  80         if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
  81                 return (NULL);
  82         return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP, true));
  83 }
  84
  85 DIR *
  86 __opendir2(const char *name, int flags)
  87 {
  88         int fd;
  89         DIR *dir;
  90         int saved_errno;
  91
  92         if ((flags & (__DTF_READALL | __DTF_SKIPREAD)) != 0)
  93                 return (NULL);
  94         if ((fd = _open(name,
  95             O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1)
  96                 return (NULL);
  97
  98         dir = __opendir_common(fd, flags, false);
  99         if (dir == NULL) {
 100                 saved_errno = errno;
 101                 _close(fd);
 102                 errno = saved_errno;
 103         }
 104         return (dir);
 105 }
 106
 107 static int
 108 opendir_compar(const void *p1, const void *p2)
 109 {
 110
 111         return (strcmp((*(const struct dirent **)p1)->d_name,
 112             (*(const struct dirent **)p2)->d_name));
 113 }
 114
 115 /*
 116  * For a directory at the top of a unionfs stack, the entire directory's
 117  * contents are read and cached locally until the next call to rewinddir().
 118  * For the fdopendir() case, the initial seek position must be preserved.
 119  * For rewinddir(), the full directory should always be re-read from the
 120  * beginning.
 121  *
 122  * If an error occurs, the existing buffer and state of 'dirp' is left
 123  * unchanged.
 124  */
 125 bool
 126 _filldir(DIR *dirp, bool use_current_pos)
 127 {
 128         struct dirent **dpv;
 129         char *buf, *ddptr, *ddeptr;
 130         off_t pos;
 131         int fd2, incr, len, n, saved_errno, space;
 132
 133         len = 0;
 134         space = 0;
 135         buf = NULL;
 136         ddptr = NULL;
 137
 138         /*
 139          * Use the system page size if that is a multiple of DIRBLKSIZ.
 140          * Hopefully this can be a big win someday by allowing page
 141          * trades to user space to be done by _getdirentries().
 142          */
 143         incr = getpagesize();
 144         if ((incr % DIRBLKSIZ) != 0)
 145                 incr = DIRBLKSIZ;
 146
 147         /*
 148          * The strategy here is to read all the directory
 149          * entries into a buffer, sort the buffer, and
 150          * remove duplicate entries by setting the inode
 151          * number to zero.
 152          *
 153          * We reopen the directory because _getdirentries()
 154          * on a MNT_UNION mount modifies the open directory,
 155          * making it refer to the lower directory after the
 156          * upper directory's entries are exhausted.
 157          * This would otherwise break software that uses
 158          * the directory descriptor for fchdir or *at
 159          * functions, such as fts.c.
 160          */
 161         if ((fd2 = openat(dirp->dd_fd, ".", O_RDONLY | O_CLOEXEC)) == -1)
 162                 return (false);
 163
 164         if (use_current_pos) {
 165                 pos = lseek(dirp->dd_fd, 0, SEEK_CUR);
 166                 if (pos == -1 || lseek(fd2, pos, SEEK_SET) == -1) {
 167                         saved_errno = errno;
 168                         _close(fd2);
 169                         errno = saved_errno;
 170                         return (false);
 171                 }
 172         }
 173
 174         do {
 175                 /*
 176                  * Always make at least DIRBLKSIZ bytes
 177                  * available to _getdirentries
 178                  */
 179                 if (space < DIRBLKSIZ) {
 180                         space += incr;
 181                         len += incr;
 182                         buf = reallocf(buf, len);
 183                         if (buf == NULL) {
 184                                 saved_errno = errno;
 185                                 _close(fd2);
 186                                 errno = saved_errno;
 187                                 return (false);
 188                         }
 189                         ddptr = buf + (len - space);
 190                 }
 191
 192 #if __DARWIN_64_BIT_INO_T
 193                 n = (int)__getdirentries64(fd2, ddptr, space, &dirp->dd_td->seekoff);
 194 #else /* !__DARWIN_64_BIT_INO_T */
 195                 n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek);
 196 #endif /* __DARWIN_64_BIT_INO_T */
 197                 if (n > 0) {
 198                         ddptr += n;
 199                         space -= n;
 200                 }
 201                 if (n < 0) {
 202                         saved_errno = errno;
 203                         _close(fd2);
 204                         errno = saved_errno;
 205                         return (false);
 206                 }
 207         } while (n > 0);
 208         _close(fd2);
 209
 210         ddeptr = ddptr;
 211
 212         /*
 213          * There is now a buffer full of (possibly) duplicate
 214          * names.
 215          */
 216         dirp->dd_buf = buf;
 217
 218         /*
 219          * Go round this loop twice...
 220          *
 221          * Scan through the buffer, counting entries.
 222          * On the second pass, save pointers to each one.
 223          * Then sort the pointers and remove duplicate names.
 224          */
 225         for (dpv = NULL;;) {
 226                 n = 0;
 227                 ddptr = buf;
 228                 while (ddptr < ddeptr) {
 229                         struct dirent *dp;
 230
 231                         dp = (struct dirent *) ddptr;
 232                         if ((long)dp & 03L)
 233                                 break;
 234                         if ((dp->d_reclen <= 0) ||
 235                             (dp->d_reclen > (ddeptr + 1 - ddptr)))
 236                                 break;
 237                         ddptr += dp->d_reclen;
 238                         if (dp->d_fileno) {
 239                                 if (dpv)
 240                                         dpv[n] = dp;
 241                                 n++;
 242                         }
 243                 }
 244
 245                 if (dpv) {
 246                         struct dirent *xp;
 247
 248                         /*
 249                          * This sort must be stable.
 250                          */
 251                         mergesort(dpv, n, sizeof(*dpv), opendir_compar);
 252
 253                         dpv[n] = NULL;
 254                         xp = NULL;
 255
 256                         /*
 257                          * Scan through the buffer in sort order,
 258                          * zapping the inode number of any
 259                          * duplicate names.
 260                          */
 261                         for (n = 0; dpv[n]; n++) {
 262                                 struct dirent *dp = dpv[n];
 263
 264                                 if ((xp == NULL) ||
 265                                     strcmp(dp->d_name, xp->d_name)) {
 266                                         xp = dp;
 267                                 } else {
 268                                         dp->d_fileno = 0;
 269                                 }
 270                                 if (dp->d_type == DT_WHT &&
 271                                     (dirp->dd_flags & DTF_HIDEW))
 272                                         dp->d_fileno = 0;
 273                         }
 274
 275                         free(dpv);
 276                         break;
 277                 } else {
 278                         dpv = malloc((n+1) * sizeof(struct dirent *));
 279                         if (dpv == NULL)
 280                                 break;
 281                 }
 282         }
 283
 284         dirp->dd_len = len;
 285         dirp->dd_size = ddptr - dirp->dd_buf;
 286         return (true);
 287 }
 288
 289
 290 /*
 291  * Common routine for opendir(3), __opendir2(3) and fdopendir(3).
 292  */
 293 static DIR *
 294 __opendir_common(int fd, int flags, bool use_current_pos)
 295 {
 296         DIR *dirp;
 297         int incr;
 298         int saved_errno;
 299         int unionstack;
 300
 301         if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
 302                 return (NULL);
 303
 304         dirp->dd_buf = NULL;
 305         dirp->dd_fd = fd;
 306         dirp->dd_flags = flags;
 307         dirp->dd_loc = 0;
 308         dirp->dd_lock = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 309         dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
 310         LIST_INIT(&dirp->dd_td->td_locq);
 311         dirp->dd_td->td_loccnt = 0;
 312
 313         /*
 314          * Use the system page size if that is a multiple of DIRBLKSIZ.
 315          * Hopefully this can be a big win someday by allowing page
 316          * trades to user space to be done by _getdirentries().
 317          */
 318         incr = getpagesize();
 319         if ((incr % DIRBLKSIZ) != 0)
 320                 incr = DIRBLKSIZ;
 321
 322         /*
 323          * Determine whether this directory is the top of a union stack.
 324          */
 325         if (flags & DTF_NODUP) {
 326                 struct statfs sfb;
 327
 328                 if (_fstatfs(fd, &sfb) < 0)
 329                         goto fail;
 330                 unionstack = !strcmp(sfb.f_fstypename, "unionfs")
 331                     || (sfb.f_flags & MNT_UNION);
 332         } else {
 333                 unionstack = 0;
 334         }
 335
 336         if (unionstack) {
 337                 if (!_filldir(dirp, use_current_pos))
 338                         goto fail;
 339                 dirp->dd_flags |= __DTF_READALL;
 340         } else {
 341                 dirp->dd_len = incr;
 342                 dirp->dd_buf = malloc(dirp->dd_len);
 343                 if (dirp->dd_buf == NULL)
 344                         goto fail;
 345                 if (use_current_pos) {
 346                         /*
 347                          * Read the first batch of directory entries
 348                          * to prime dd_seek.  This also checks if the
 349                          * fd passed to fdopendir() is a directory.
 350                          */
 351 #if __DARWIN_64_BIT_INO_T
 352                         dirp->dd_size = (long)__getdirentries64(dirp->dd_fd,
 353                             dirp->dd_buf, dirp->dd_len, &dirp->dd_td->seekoff);
 354 #else /* !__DARWIN_64_BIT_INO_T */
 355                         dirp->dd_size = _getdirentries(dirp->dd_fd,
 356                             dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
 357 #endif /* __DARWIN_64_BIT_INO_T */
 358                         if (dirp->dd_size < 0) {
 359                                 if (errno == EINVAL)
 360                                         errno = ENOTDIR;
 361                                 goto fail;
 362                         }
 363                         dirp->dd_flags |= __DTF_SKIPREAD;
 364                 } else {
 365                         dirp->dd_size = 0;
 366 #if __DARWIN_64_BIT_INO_T
 367                         dirp->dd_td->seekoff = 0;
 368 #else /* !__DARWIN_64_BIT_INO_T */
 369                         dirp->dd_seek = 0;
 370 #endif /* __DARWIN_64_BIT_INO_T */
 371                 }
 372         }
 373
 374         return (dirp);
 375
 376 fail:
 377         saved_errno = errno;
 378         free(dirp->dd_buf);
 379         free(dirp);
 380         errno = saved_errno;
 381         return (NULL);
 382 }