sysdeps/unix/readdir.c

   1 /* Copyright (C) 1991,92,93,94,95,96,97,99,2000 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    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 #ifndef __READDIR
  31 # define __READDIR __readdir
  32 # define __GETDENTS __getdents
  33 # define DIRENT_TYPE struct dirent
  34 # define __READDIR_ALIAS
  35 #endif
  36
  37 /* Read a directory entry from DIRP.  */
  38 DIRENT_TYPE *
  39 __READDIR (DIR *dirp)
  40 {
  41   DIRENT_TYPE *dp;
  42   int saved_errno = errno;
  43
  44   __libc_lock_lock (dirp->lock);
  45
  46   do
  47     {
  48       size_t reclen;
  49
  50       if (dirp->offset >= dirp->size)
  51         {
  52           /* We've emptied out our buffer.  Refill it.  */
  53
  54           size_t maxread;
  55           ssize_t bytes;
  56
  57 #ifndef _DIRENT_HAVE_D_RECLEN
  58           /* Fixed-size struct; must read one at a time (see below).  */
  59           maxread = sizeof *dp;
  60 #else
  61           maxread = dirp->allocation;
  62 #endif
  63
  64           bytes = __GETDENTS (dirp->fd, dirp->data, maxread);
  65           if (bytes <= 0)
  66             {
  67               /* Don't modifiy errno when reaching EOF.  */
  68               if (bytes == 0)
  69                 __set_errno (saved_errno);
  70               dp = NULL;
  71               break;
  72             }
  73           dirp->size = (size_t) bytes;
  74
  75           /* Reset the offset into the buffer.  */
  76           dirp->offset = 0;
  77         }
  78
  79       dp = (DIRENT_TYPE *) &dirp->data[dirp->offset];
  80
  81 #ifdef _DIRENT_HAVE_D_RECLEN
  82       reclen = dp->d_reclen;
  83 #else
  84       /* The only version of `struct dirent*' that lacks `d_reclen'
  85          is fixed-size.  */
  86       assert (sizeof dp->d_name > 1);
  87       reclen = sizeof *dp;
  88       /* The name is not terminated if it is the largest possible size.
  89          Clobber the following byte to ensure proper null termination.  We
  90          read jst one entry at a time above so we know that byte will not
  91          be used later.  */
  92       dp->d_name[sizeof dp->d_name] = '\0';
  93 #endif
  94
  95       dirp->offset += reclen;
  96
  97 #ifdef _DIRENT_HAVE_D_OFF
  98       dirp->filepos = dp->d_off;
  99 #else
 100       dirp->filepos += reclen;
 101 #endif
 102
 103       /* Skip deleted files.  */
 104     } while (dp->d_ino == 0);
 105
 106   __libc_lock_unlock (dirp->lock);
 107
 108   return dp;
 109 }
 110
 111 #ifdef __READDIR_ALIAS
 112 weak_alias (__readdir, readdir)
 113 #endif