1/* Copyright (C) 1991-2020 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 <limits.h>
20#include <stddef.h>
21#include <string.h>
22#include <dirent.h>
23#include <unistd.h>
24#include <sys/types.h>
25#include <assert.h>
26
27#include <dirstream.h>
28
29#ifndef __READDIR
30# define __READDIR __readdir
31# define __GETDENTS __getdents
32# define DIRENT_TYPE struct dirent
33# define __READDIR_ALIAS
34#endif
35
36/* Read a directory entry from DIRP. */
37DIRENT_TYPE *
38__READDIR (DIR *dirp)
39{
40 DIRENT_TYPE *dp;
41 int saved_errno = errno;
42
43#if IS_IN (libc)
44 __libc_lock_lock (dirp->lock);
45#endif
46
47 do
48 {
49 size_t reclen;
50
51 if (dirp->offset >= dirp->size)
52 {
53 /* We've emptied out our buffer. Refill it. */
54
55 size_t maxread;
56 ssize_t bytes;
57
58#ifndef _DIRENT_HAVE_D_RECLEN
59 /* Fixed-size struct; must read one at a time (see below). */
60 maxread = sizeof *dp;
61#else
62 maxread = dirp->allocation;
63#endif
64
65 bytes = __GETDENTS (dirp->fd, dirp->data, maxread);
66 if (bytes <= 0)
67 {
68 /* On some systems getdents fails with ENOENT when the
69 open directory has been rmdir'd already. POSIX.1
70 requires that we treat this condition like normal EOF. */
71 if (bytes < 0 && errno == ENOENT)
72 bytes = 0;
73
74 /* Don't modifiy errno when reaching EOF. */
75 if (bytes == 0)
76 __set_errno (saved_errno);
77 dp = NULL;
78 break;
79 }
80 dirp->size = (size_t) bytes;
81
82 /* Reset the offset into the buffer. */
83 dirp->offset = 0;
84 }
85
86 dp = (DIRENT_TYPE *) &dirp->data[dirp->offset];
87
88#ifdef _DIRENT_HAVE_D_RECLEN
89 reclen = dp->d_reclen;
90#else
91 /* The only version of `struct dirent*' that lacks `d_reclen'
92 is fixed-size. */
93 assert (sizeof dp->d_name > 1);
94 reclen = sizeof *dp;
95 /* The name is not terminated if it is the largest possible size.
96 Clobber the following byte to ensure proper null termination. We
97 read jst one entry at a time above so we know that byte will not
98 be used later. */
99 dp->d_name[sizeof dp->d_name] = '\0';
100#endif
101
102 dirp->offset += reclen;
103
104#ifdef _DIRENT_HAVE_D_OFF
105 dirp->filepos = dp->d_off;
106#else
107 dirp->filepos += reclen;
108#endif
109
110 /* Skip deleted files. */
111 } while (dp->d_ino == 0);
112
113#if IS_IN (libc)
114 __libc_lock_unlock (dirp->lock);
115#endif
116
117 return dp;
118}
119
120#ifdef __READDIR_ALIAS
121weak_alias (__readdir, readdir)
122#endif
123
124#undef __READDIR
125#undef __GETDENTS
126#undef DIRENT_TYPE
127#undef __READDIR_ALIAS
128