lib/libc/gen/initdir.c

   1 /*      $NetBSD: initdir.c,v 1.3 2012/03/13 21:13:36 christos Exp $     */
   2
   3 /*
   4  * Copyright (c) 1983, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 __RCSID("$NetBSD: initdir.c,v 1.3 2012/03/13 21:13:36 christos Exp $");
  35 #endif /* LIBC_SCCS and not lint */
  36
  37 #include "namespace.h"
  38 #include "reentrant.h"
  39 #include "extern.h"
  40
  41 #include <sys/param.h>
  42
  43 #include <assert.h>
  44 #include <dirent.h>
  45 #include <errno.h>
  46 #include <fcntl.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50
  51 #include "dirent_private.h"
  52
  53 #define MAXITERATIONS   100
  54
  55 int
  56 _initdir(DIR *dirp, int fd, const char *name)
  57 {
  58         int flags = dirp->dd_flags;
  59         int pagesz;
  60         int incr;
  61
  62         /*
  63          * If the machine's page size is an exact multiple of DIRBLKSIZ,
  64          * use a buffer that is cluster boundary aligned.
  65          * Hopefully this can be a big win someday by allowing page trades
  66          * to user space to be done by getdents()
  67          */
  68         if (((pagesz = getpagesize()) % DIRBLKSIZ) == 0)
  69                 incr = pagesz;
  70         else
  71                 incr = DIRBLKSIZ;
  72
  73         if ((flags & DTF_REWIND) && name == NULL) {
  74                 return EINVAL;
  75         }
  76         if ((flags & __DTF_READALL) != 0) {
  77                 size_t len;
  78                 size_t space;
  79                 char *buf, *nbuf;
  80                 char *ddptr;
  81                 char *ddeptr;
  82                 int n;
  83                 struct dirent **dpv;
  84                 int i;
  85
  86                 /*
  87                  * The strategy here for directories on top of a union stack
  88                  * is to read all the directory entries into a buffer, sort
  89                  * the buffer, and remove duplicate entries by setting the
  90                  * inode number to zero.
  91                  *
  92                  * For directories on an NFS mounted filesystem, we try
  93                  * to get a consistent snapshot by trying until we have
  94                  * successfully read all of the directory without errors
  95                  * (i.e. 'bad cookie' errors from the server because
  96                  * the directory was modified). These errors should not
  97                  * happen often, but need to be dealt with.
  98                  */
  99                 i = 0;
 100 retry:
 101                 len = 0;
 102                 space = 0;
 103                 buf = 0;
 104                 ddptr = 0;
 105
 106                 do {
 107                         /*
 108                          * Always make at least DIRBLKSIZ bytes
 109                          * available to getdents
 110                          */
 111                         if (space < DIRBLKSIZ) {
 112                                 space += incr;
 113                                 len += incr;
 114                                 nbuf = realloc(buf, len);
 115                                 if (nbuf == NULL) {
 116                                         dirp->dd_buf = buf;
 117                                         return errno;
 118                                 }
 119                                 buf = nbuf;
 120                                 ddptr = buf + (len - space);
 121                         }
 122
 123                         dirp->dd_seek = lseek(fd, (off_t)0, SEEK_CUR);
 124                         n = getdents(fd, ddptr, space);
 125                         /*
 126                          * For NFS: EINVAL means a bad cookie error
 127                          * from the server. Keep trying to get a
 128                          * consistent view, in this case this means
 129                          * starting all over again.
 130                          */
 131                         if (n == -1 && errno == EINVAL &&
 132                             (flags & __DTF_RETRY_ON_BADCOOKIE) != 0) {
 133                                 free(buf);
 134                                 lseek(fd, (off_t)0, SEEK_SET);
 135                                 if (++i > MAXITERATIONS)
 136                                         return EINVAL;
 137                                 goto retry;
 138                         }
 139                         if (n > 0) {
 140                                 ddptr += n;
 141                                 space -= n;
 142                         }
 143                 } while (n > 0);
 144
 145                 ddeptr = ddptr;
 146
 147                 /*
 148                  * Re-open the directory.
 149                  * This has the effect of rewinding back to the
 150                  * top of the union stack and is needed by
 151                  * programs which plan to fchdir to a descriptor
 152                  * which has also been read -- see fts.c.
 153                  */
 154                 if (flags & DTF_REWIND) {
 155                         (void) close(fd);
 156                         if ((fd = open(name, O_RDONLY | O_CLOEXEC)) == -1) {
 157                                 dirp->dd_buf = buf;
 158                                 return errno;
 159                         }
 160                 }
 161
 162                 /*
 163                  * There is now a buffer full of (possibly) duplicate
 164                  * names.
 165                  */
 166                 dirp->dd_buf = buf;
 167
 168                 /*
 169                  * Go round this loop twice...
 170                  *
 171                  * Scan through the buffer, counting entries.
 172                  * On the second pass, save pointers to each one.
 173                  * Then sort the pointers and remove duplicate names.
 174                  */
 175                 if ((flags & DTF_NODUP) != 0) {
 176                         for (dpv = 0;;) {
 177                                 for (n = 0, ddptr = buf; ddptr < ddeptr;) {
 178                                         struct dirent *dp;
 179
 180                                         dp = (struct dirent *)(void *)ddptr;
 181                                         if ((long)dp & _DIRENT_ALIGN(dp))
 182                                                 break;
 183                                         /*
 184                                          * d_reclen is unsigned,
 185                                          * so no need to compare <= 0
 186                                          */
 187                                         if (dp->d_reclen > (ddeptr + 1 - ddptr))
 188                                                 break;
 189                                         ddptr += dp->d_reclen;
 190                                         if (dp->d_fileno) {
 191                                                 if (dpv)
 192                                                         dpv[n] = dp;
 193                                                 n++;
 194                                         }
 195                                 }
 196
 197                                 if (dpv) {
 198                                         struct dirent *xp;
 199
 200                                         /*
 201                                          * This sort must be stable.
 202                                          */
 203                                         mergesort(dpv, (size_t)n, sizeof(*dpv),
 204                                             alphasort);
 205
 206                                         dpv[n] = NULL;
 207                                         xp = NULL;
 208
 209                                         /*
 210                                          * Scan through the buffer in sort
 211                                          * order, zapping the inode number
 212                                          * of any duplicate names.
 213                                          */
 214                                         for (n = 0; dpv[n]; n++) {
 215                                                 struct dirent *dp = dpv[n];
 216
 217                                                 if ((xp == NULL) ||
 218                                                     strcmp(dp->d_name,
 219                                                       xp->d_name))
 220                                                         xp = dp;
 221                                                 else
 222                                                         dp->d_fileno = 0;
 223 #if !defined(__minix)
 224                                                 if (dp->d_type == DT_WHT &&
 225                                                     (flags & DTF_HIDEW))
 226                                                         dp->d_fileno = 0;
 227 #endif /* !defined(__minix) */
 228                                         }
 229
 230                                         free(dpv);
 231                                         break;
 232                                 } else {
 233                                         dpv = malloc((n + 1) *
 234                                             sizeof(struct dirent *));
 235                                         if (dpv == NULL)
 236                                                 break;
 237                                 }
 238                         }
 239                 }
 240
 241                 _DIAGASSERT(__type_fit(int, len));
 242                 dirp->dd_len = (int)len;
 243                 dirp->dd_size = ddptr - dirp->dd_buf;
 244         } else {
 245                 dirp->dd_len = incr;
 246                 dirp->dd_buf = malloc((size_t)dirp->dd_len);
 247                 if (dirp->dd_buf == NULL)
 248                         return errno;
 249                 dirp->dd_seek = 0;
 250                 flags &= ~DTF_REWIND;
 251         }
 252         dirp->dd_loc = 0;
 253         dirp->dd_fd = fd;
 254         dirp->dd_flags = flags;
 255         /*
 256          * Set up seek point for rewinddir.
 257          */
 258         (void)_telldir_unlocked(dirp);
 259         return 0;
 260 }
 261
 262 void
 263 _finidir(DIR *dirp)
 264 {
 265         struct dirpos *poslist;
 266
 267         free(dirp->dd_buf);
 268
 269         /* free seekdir/telldir storage */
 270         for (poslist = dirp->dd_internal; poslist; ) {
 271                 struct dirpos *nextpos = poslist->dp_next;
 272                 free(poslist);
 273                 poslist = nextpos;
 274         }
 275         dirp->dd_internal = NULL;
 276 }