1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
/* A more POSIX-compliant lchown
Copyright (C) 1998-1999, 2002, 2004, 2006-2007, 2009-2026 Free Software
Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* written by Jim Meyering */
#include <config.h>
/* Specification. */
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include "issymlink.h"
#include "stat-time.h"
#ifndef CHOWN_CHANGE_TIME_BUG
# define CHOWN_CHANGE_TIME_BUG 0
#endif
#ifndef CHOWN_MODIFIES_SYMLINK
# define CHOWN_MODIFIES_SYMLINK 0
#endif
#ifndef CHOWN_TRAILING_SLASH_BUG
# define CHOWN_TRAILING_SLASH_BUG 0
#endif
/* Gnulib target platforms lacking utimensat do not need it,
because in practice the bug it works around does not occur. */
#if !HAVE_UTIMENSAT
# undef utimensat
# define utimensat(fd, file, times, flag) \
((void) (fd), (void) (file), (void) (times), (void) (flag), \
0)
#endif
#if !HAVE_LCHOWN
/* If the system chown does not follow symlinks, we don't want it
replaced by gnulib's chown, which does follow symlinks. */
# if CHOWN_MODIFIES_SYMLINK /* native Windows and some very old platforms */
# undef chown
# endif
/* Work just like chown, except when FILE is a symbolic link.
In that case, set errno to EOPNOTSUPP and return -1.
But if autoconf tests determined that chown modifies
symlinks, then just call chown. */
int
lchown (_GL_UNUSED char const *file, _GL_UNUSED uid_t owner,
_GL_UNUSED gid_t group)
{
# if HAVE_CHOWN
if (!CHOWN_MODIFIES_SYMLINK && 0 < issymlink (file))
{
errno = EOPNOTSUPP;
return -1;
}
return chown (file, owner, group);
# else /* !HAVE_CHOWN */
errno = ENOSYS;
return -1;
# endif
}
#else /* HAVE_LCHOWN */
/* Below we refer to the system's function. */
# undef lchown
/* Provide a more-closely POSIX-conforming version. */
int
rpl_lchown (const char *file, uid_t owner, gid_t group)
{
gid_t no_gid = -1;
uid_t no_uid = -1;
bool gid_noop = group == no_gid;
bool uid_noop = owner == no_uid;
bool change_time_check = CHOWN_CHANGE_TIME_BUG && !(gid_noop & uid_noop);
struct stat st;
if (change_time_check
|| (CHOWN_TRAILING_SLASH_BUG
&& file[0] && file[strlen (file) - 1] == '/'))
{
bool file_is_symlink = false;
int r = lstat (file, &st);
if (0 <= r)
file_is_symlink = !!S_ISLNK (st.st_mode);
else if (errno != EOVERFLOW)
return r;
else
{
int s = issymlink (file);
if (s < 0)
return s;
if (0 < s)
{
errno = EOVERFLOW;
return -1;
}
/* FILE exists and is not a symbolic link; ST is unset.
Rely on Gnulib chown to work around platform chown bugs. */
}
if (!file_is_symlink)
return chown (file, owner, group);
}
int result = lchown (file, owner, group);
/* If no change in ownership, but at least one argument was not -1,
update ctime indirectly via a no-change update to atime and mtime.
Do not use UTIME_NOW or UTIME_OMIT as they might run into bugs
on some platforms. Do not communicate any failure to the caller
as that would be worse than communicating the ownership change. */
if (result == 0 && change_time_check
&& (((owner == st.st_uid) | uid_noop)
& ((group == st.st_gid) | gid_noop)))
utimensat (AT_FDCWD, file,
((struct timespec[]) { get_stat_atime (&st),
get_stat_mtime (&st) }),
AT_SYMLINK_NOFOLLOW);
return result;
}
#endif /* HAVE_LCHOWN */
|
