sysdeps/unix/sysv/linux/readdir_r.c

   1 /* Read a directory in reentrant mode.  Linux no-LFS version.
   2    Copyright (C) 2018-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <dirent.h>
  20
  21 #if !_DIRENT_MATCHES_DIRENT64
  22 /* Read a directory entry from DIRP.  */
  23 int
  24 __readdir_r (DIR *dirp, struct dirent *entry, struct dirent **result)
  25 {
  26   struct dirent *dp;
  27   size_t reclen;
  28
  29   __libc_lock_lock (dirp->lock);
  30
  31   while (1)
  32     {
  33       dp = __readdir_unlocked (dirp);
  34       if (dp == NULL)
  35         break;
  36
  37       reclen = dp->d_reclen;
  38       if (reclen <= offsetof (struct dirent, d_name) + NAME_MAX + 1)
  39         break;
  40
  41       /* The record is very long.  It could still fit into the caller-supplied
  42          buffer if we can skip padding at the end.  */
  43       size_t namelen = _D_EXACT_NAMLEN (dp);
  44       if (namelen <= NAME_MAX)
  45         {
  46           reclen = offsetof (struct dirent, d_name) + namelen + 1;
  47           break;
  48         }
  49
  50       /* The name is too long.  Ignore this file.  */
  51       dirp->errcode = ENAMETOOLONG;
  52     }
  53
  54   if (dp != NULL)
  55     {
  56       *result = memcpy (entry, dp, reclen);
  57       entry->d_reclen = reclen;
  58     }
  59   else
  60     *result = NULL;
  61
  62   __libc_lock_unlock (dirp->lock);
  63
  64   return dp != NULL ? 0 : dirp->errcode;
  65 }
  66
  67 weak_alias (__readdir_r, readdir_r)
  68 #endif /* _DIRENT_MATCHES_DIRENT64  */