1 /* Read a directory.  Linux no-LFS version.
2    Copyright (C) 2018-2022 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 #include <dirstream.h>
23 
24 /* Read a directory entry from DIRP.  */
25 struct dirent *
__readdir_unlocked(DIR * dirp)26 __readdir_unlocked (DIR *dirp)
27 {
28   struct dirent *dp;
29   int saved_errno = errno;
30 
31   do
32     {
33       size_t reclen;
34 
35       if (dirp->offset >= dirp->size)
36 	{
37 	  /* We've emptied out our buffer.  Refill it.  */
38 
39 	  size_t maxread = dirp->allocation;
40 	  ssize_t bytes;
41 
42 	  bytes = __getdents (dirp->fd, dirp->data, maxread);
43 	  if (bytes <= 0)
44 	    {
45 	      /* On some systems getdents fails with ENOENT when the
46 		 open directory has been rmdir'd already.  POSIX.1
47 		 requires that we treat this condition like normal EOF.  */
48 	      if (bytes < 0 && errno == ENOENT)
49 		bytes = 0;
50 
51 	      /* Don't modifiy errno when reaching EOF.  */
52 	      if (bytes == 0)
53 		__set_errno (saved_errno);
54 	      dp = NULL;
55 	      break;
56 	    }
57 	  dirp->size = (size_t) bytes;
58 
59 	  /* Reset the offset into the buffer.  */
60 	  dirp->offset = 0;
61 	}
62 
63       dp = (struct dirent *) &dirp->data[dirp->offset];
64 
65       reclen = dp->d_reclen;
66 
67       dirp->offset += reclen;
68 
69       dirp->filepos = dp->d_off;
70 
71       /* Skip deleted files.  */
72     } while (dp->d_ino == 0);
73 
74   return dp;
75 }
76 
77 struct dirent *
__readdir(DIR * dirp)78 __readdir (DIR *dirp)
79 {
80   struct dirent *dp;
81 
82 #if IS_IN (libc)
83   __libc_lock_lock (dirp->lock);
84 #endif
85   dp = __readdir_unlocked (dirp);
86 #if IS_IN (libc)
87   __libc_lock_unlock (dirp->lock);
88 #endif
89 
90   return dp;
91 }
92 weak_alias (__readdir, readdir)
93 
94 #endif
95