sysdeps/unix/sysv/linux/readdir64_r.c

   1 /* Copyright (C) 1997, 1998 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <string.h>
  23 #include <dirent.h>
  24 #include <unistd.h>
  25 #include <sys/types.h>
  26 #include <assert.h>
  27
  28 #include <dirstream.h>
  29
  30 extern ssize_t __getdirentries64 (int, char *, size_t, off_t *);
  31
  32
  33 /* Read a directory entry from DIRP, store result in ENTRY and return
  34    pointer to result in *RESULT.  */
  35 int
  36 readdir64_r (DIR *dirp, struct dirent64 *entry, struct dirent64 **result)
  37 {
  38   struct dirent64 *dp;
  39   size_t reclen;
  40
  41   __libc_lock_lock (dirp->lock);
  42
  43   do
  44     {
  45       if (dirp->offset >= dirp->size)
  46         {
  47           /* We've emptied out our buffer.  Refill it.  */
  48
  49           size_t maxread;
  50           off_t base;
  51           ssize_t bytes;
  52
  53 #ifndef _DIRENT_HAVE_D_RECLEN
  54           /* Fixed-size struct; must read one at a time (see below).  */
  55           maxread = sizeof *dp;
  56 #else
  57           maxread = dirp->allocation;
  58 #endif
  59
  60           base = dirp->filepos;
  61           bytes = __getdirentries64 (dirp->fd, dirp->data, maxread, &base);
  62           if (bytes <= 0)
  63             {
  64               dp = NULL;
  65               /* Reclen != 0 signals that an error occurred.  */
  66               reclen = bytes != 0;
  67               break;
  68             }
  69           dirp->size = (size_t) bytes;
  70
  71           /* Reset the offset into the buffer.  */
  72           dirp->offset = 0;
  73         }
  74
  75       dp = (struct dirent64 *) &dirp->data[dirp->offset];
  76
  77 #ifdef _DIRENT_HAVE_D_RECLEN
  78       reclen = dp->d_reclen;
  79 #else
  80       /* The only version of `struct dirent64' that lacks `d_reclen'
  81          is fixed-size.  */
  82       assert (sizeof dp->d_name > 1);
  83       reclen = sizeof *dp;
  84       /* The name is not terminated if it is the largest possible size.
  85          Clobber the following byte to ensure proper null termination.  We
  86          read just one entry at a time above so we know that byte will not
  87          be used later.  */
  88       dp->d_name[sizeof dp->d_name] = '\0';
  89 #endif
  90
  91       dirp->offset += reclen;
  92
  93 #ifdef _DIRENT_HAVE_D_OFF
  94       dirp->filepos = dp->d_off;
  95 #else
  96       dirp->filepos += reclen;
  97 #endif
  98
  99       /* Skip deleted files.  */
 100     }
 101   while (dp->d_ino == 0);
 102
 103   if (dp != NULL)
 104     *result = memcpy (entry, dp, reclen);
 105   else
 106     *result = NULL;
 107
 108   __libc_lock_unlock (dirp->lock);
 109
 110   return dp != NULL ? 0 : reclen ? errno : 0;
 111 }