lib/libc/gen/initdir.c

   1 /*      $NetBSD: initdir.c,v 1.1 2010/09/26 02:26:59 yamt 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 1.1 2010/09/26 02:26:59 yamt Exp $");
  35 #endif /* LIBC_SCCS and not lint */
  36
  37 #include "namespace.h"
  38
  39 #ifdef __minix
  40 /* NetBSD BUG on !_REENTRANT */
  41 #include <sys/cdefs.h>
  42 #include <sys/featuretest.h>
  43 #include <sys/types.h>
  44 #endif
  45
  46 #include "reentrant.h"
  47 #include "extern.h"
  48
  49 #include <sys/param.h>
  50
  51 #include <assert.h>
  52 #include <dirent.h>
  53 #include <errno.h>
  54 #include <fcntl.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58
  59 #include "dirent_private.h"
  60
  61 #define MAXITERATIONS   100
  62
  63 int
  64 _initdir(DIR *dirp, int fd, const char *name)
  65 {
  66         int flags = dirp->dd_flags;
  67         int pagesz;
  68         int incr;
  69
  70         /*
  71          * If the machine's page size is an exact multiple of DIRBLKSIZ,
  72          * use a buffer that is cluster boundary aligned.
  73          * Hopefully this can be a big win someday by allowing page trades
  74          * to user space to be done by getdents()
  75          */
  76         if (((pagesz = getpagesize()) % DIRBLKSIZ) == 0)
  77                 incr = pagesz;
  78         else
  79                 incr = DIRBLKSIZ;
  80
  81         if ((flags & DTF_REWIND) && name == NULL) {
  82                 return EINVAL;
  83         }
  84         if ((flags & __DTF_READALL) != 0) {
  85                 size_t len;
  86                 size_t space;
  87                 char *buf, *nbuf;
  88                 char *ddptr;
  89                 char *ddeptr;
  90                 int n;
  91                 struct dirent **dpv;
  92                 int i;
  93
  94                 /*
  95                  * The strategy here for directories on top of a union stack
  96                  * is to read all the directory entries into a buffer, sort
  97                  * the buffer, and remove duplicate entries by setting the
  98                  * inode number to zero.
  99                  *
 100                  * For directories on an NFS mounted filesystem, we try
 101                  * to get a consistent snapshot by trying until we have
 102                  * successfully read all of the directory without errors
 103                  * (i.e. 'bad cookie' errors from the server because
 104                  * the directory was modified). These errors should not
 105                  * happen often, but need to be dealt with.
 106                  */
 107                 i = 0;
 108 retry:
 109                 len = 0;
 110                 space = 0;
 111                 buf = 0;
 112                 ddptr = 0;
 113
 114                 do {
 115                         /*
 116                          * Always make at least DIRBLKSIZ bytes
 117                          * available to getdents
 118                          */
 119                         if (space < DIRBLKSIZ) {
 120                                 space += incr;
 121                                 len += incr;
 122                                 nbuf = realloc(buf, len);
 123                                 if (nbuf == NULL) {
 124                                         dirp->dd_buf = buf;
 125                                         return errno;
 126                                 }
 127                                 buf = nbuf;
 128                                 ddptr = buf + (len - space);
 129                         }
 130
 131                         dirp->dd_seek = lseek(fd, (off_t)0, SEEK_CUR);
 132                         n = getdents(fd, ddptr, space);
 133                         /*
 134                          * For NFS: EINVAL means a bad cookie error
 135                          * from the server. Keep trying to get a
 136                          * consistent view, in this case this means
 137                          * starting all over again.
 138                          */
 139                         if (n == -1 && errno == EINVAL &&
 140                             (flags & __DTF_RETRY_ON_BADCOOKIE) != 0) {
 141                                 free(buf);
 142                                 lseek(fd, (off_t)0, SEEK_SET);
 143                                 if (++i > MAXITERATIONS)
 144                                         return EINVAL;
 145                                 goto retry;
 146                         }
 147                         if (n > 0) {
 148                                 ddptr += n;
 149                                 space -= n;
 150                         }
 151                 } while (n > 0);
 152
 153                 ddeptr = ddptr;
 154
 155                 /*
 156                  * Re-open the directory.
 157                  * This has the effect of rewinding back to the
 158                  * top of the union stack and is needed by
 159                  * programs which plan to fchdir to a descriptor
 160                  * which has also been read -- see fts.c.
 161                  */
 162                 if (flags & DTF_REWIND) {
 163                         (void) close(fd);
 164                         if ((fd = open(name, O_RDONLY)) == -1 ||
 165                             fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
 166                                 dirp->dd_buf = buf;
 167                                 return errno;
 168                         }
 169                 }
 170
 171                 /*
 172                  * There is now a buffer full of (possibly) duplicate
 173                  * names.
 174                  */
 175                 dirp->dd_buf = buf;
 176
 177                 /*
 178                  * Go round this loop twice...
 179                  *
 180                  * Scan through the buffer, counting entries.
 181                  * On the second pass, save pointers to each one.
 182                  * Then sort the pointers and remove duplicate names.
 183                  */
 184                 if ((flags & DTF_NODUP) != 0) {
 185                         for (dpv = 0;;) {
 186                                 for (n = 0, ddptr = buf; ddptr < ddeptr;) {
 187                                         struct dirent *dp;
 188
 189                                         dp = (struct dirent *)(void *)ddptr;
 190                                         if ((long)dp & _DIRENT_ALIGN(dp))
 191                                                 break;
 192                                         /*
 193                                          * d_reclen is unsigned,
 194                                          * so no need to compare <= 0
 195                                          */
 196                                         if (dp->d_reclen > (ddeptr + 1 - ddptr))
 197                                                 break;
 198                                         ddptr += dp->d_reclen;
 199                                         if (dp->d_fileno) {
 200                                                 if (dpv)
 201                                                         dpv[n] = dp;
 202                                                 n++;
 203                                         }
 204                                 }
 205
 206                                 if (dpv) {
 207                                         struct dirent *xp;
 208
 209                                         /*
 210                                          * This sort must be stable.
 211                                          */
 212                                         mergesort(dpv, (size_t)n, sizeof(*dpv),
 213                                             alphasort);
 214
 215                                         dpv[n] = NULL;
 216                                         xp = NULL;
 217
 218                                         /*
 219                                          * Scan through the buffer in sort
 220                                          * order, zapping the inode number
 221                                          * of any duplicate names.
 222                                          */
 223                                         for (n = 0; dpv[n]; n++) {
 224                                                 struct dirent *dp = dpv[n];
 225
 226                                                 if ((xp == NULL) ||
 227                                                     strcmp(dp->d_name,
 228                                                       xp->d_name))
 229                                                         xp = dp;
 230                                                 else
 231                                                         dp->d_fileno = 0;
 232 #ifndef __minix
 233                                                 if (dp->d_type == DT_WHT &&
 234                                                     (flags & DTF_HIDEW))
 235                                                         dp->d_fileno = 0;
 236 #endif
 237                                         }
 238
 239                                         free(dpv);
 240                                         break;
 241                                 } else {
 242                                         dpv = malloc((n + 1) *
 243                                             sizeof(struct dirent *));
 244                                         if (dpv == NULL)
 245                                                 break;
 246                                 }
 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_buf = malloc((size_t)dirp->dd_len);
 255                 if (dirp->dd_buf == NULL)
 256                         return errno;
 257                 dirp->dd_seek = 0;
 258                 flags &= ~DTF_REWIND;
 259         }
 260         dirp->dd_loc = 0;
 261         dirp->dd_fd = fd;
 262         dirp->dd_flags = flags;
 263         /*
 264          * Set up seek point for rewinddir.
 265          */
 266         (void)_telldir_unlocked(dirp);
 267         return 0;
 268 }
 269
 270 void
 271 _finidir(DIR *dirp)
 272 {
 273         struct dirpos *poslist;
 274
 275         free(dirp->dd_buf);
 276
 277         /* free seekdir/telldir storage */
 278         for (poslist = dirp->dd_internal; poslist; ) {
 279                 struct dirpos *nextpos = poslist->dp_next;
 280                 free(poslist);
 281                 poslist = nextpos;
 282         }
 283         dirp->dd_internal = NULL;
 284 }