1 | /* Copyright (C) 1993-2022 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, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <errno.h> |
19 | #include <stddef.h> |
20 | #include <dirent.h> |
21 | #include <unistd.h> |
22 | #include <endian.h> |
23 | #include <assert.h> |
24 | |
25 | /* Read a directory entry from DIRP. */ |
26 | struct dirent * |
27 | __readdir (DIR *dirp) |
28 | { |
29 | struct dirent64 *entry64 = __readdir64 (dirp); |
30 | |
31 | if (sizeof (struct dirent64) == sizeof (struct dirent)) |
32 | /* We should in fact just be an alias to readdir64 on this machine. */ |
33 | return (struct dirent *) entry64; |
34 | |
35 | /* These are all compile-time constants. We know that d_ino is the first |
36 | member and that the layout of the following members matches exactly in |
37 | both structures. */ |
38 | assert (offsetof (struct dirent, d_ino) == 0); |
39 | assert (offsetof (struct dirent64, d_ino) == 0); |
40 | # define MATCH(memb) \ |
41 | assert (offsetof (struct dirent64, memb) - sizeof (entry64->d_ino) \ |
42 | == offsetof (struct dirent, memb) - sizeof (ino_t)) |
43 | MATCH (d_reclen); |
44 | MATCH (d_type); |
45 | MATCH (d_namlen); |
46 | # undef MATCH |
47 | |
48 | if (entry64 == NULL) |
49 | return NULL; |
50 | |
51 | struct dirent *const entry = ((void *) (&entry64->d_ino + 1) |
52 | - sizeof entry->d_ino); |
53 | const ino_t d_ino = entry64->d_ino; |
54 | if (d_ino != entry64->d_ino) |
55 | { |
56 | __set_errno (EOVERFLOW); |
57 | return NULL; |
58 | } |
59 | # if BYTE_ORDER != BIG_ENDIAN /* We just skipped over the zero high word. */ |
60 | entry->d_ino = d_ino; /* ... or the nonzero low word, swap it. */ |
61 | # endif |
62 | entry->d_reclen -= sizeof entry64->d_ino - sizeof entry->d_ino; |
63 | return entry; |
64 | } |
65 | |
66 | weak_alias (__readdir, readdir) |
67 | |