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
| | /* Change the protections of file relative to an open directory.
Copyright (C) 2006, 2009-2020 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* written by Jim Meyering and Paul Eggert */
/* If the user's config.h happens to include <sys/stat.h>, let it include only
the system's <sys/stat.h> here, so that orig_fchmodat doesn't recurse to
rpl_fchmodat. */
#define __need_system_sys_stat_h
#include <config.h>
/* Specification. */
#include <sys/stat.h>
#undef __need_system_sys_stat_h
#if HAVE_FCHMODAT
static int
orig_fchmodat (int dir, char const *file, mode_t mode, int flags)
{
return fchmodat (dir, file, mode, flags);
}
#endif
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef __osf__
/* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
eliminates this include because of the preliminary #include <sys/stat.h>
above. */
# include "sys/stat.h"
#else
# include <sys/stat.h>
#endif
#include <intprops.h>
/* Invoke chmod or lchmod on FILE, using mode MODE, in the directory
open on descriptor FD. If possible, do it without changing the
working directory. Otherwise, resort to using save_cwd/fchdir,
then (chmod|lchmod)/restore_cwd. If either the save_cwd or the
restore_cwd fails, then give a diagnostic and exit nonzero.
Note that an attempt to use a FLAG value of AT_SYMLINK_NOFOLLOW
on a system without lchmod support causes this function to fail. */
#if HAVE_FCHMODAT
int
fchmodat (int dir, char const *file, mode_t mode, int flags)
{
# if NEED_FCHMODAT_NONSYMLINK_FIX
if (flags == AT_SYMLINK_NOFOLLOW)
{
struct stat st;
# if defined O_PATH && defined AT_EMPTY_PATH \
&& (defined __linux__ || defined __ANDROID__)
/* Open a file descriptor with O_NOFOLLOW, to make sure we don't
follow symbolic links, if /proc is mounted. O_PATH is used to
avoid a failure if the file is not readable.
Cf. <https://sourceware.org/bugzilla/show_bug.cgi?id=14578> */
int fd = openat (dir, file, O_PATH | O_NOFOLLOW | O_CLOEXEC);
if (fd < 0)
return fd;
/* Up to Linux 5.3 at least, when FILE refers to a symbolic link, the
chmod call below will change the permissions of the symbolic link
- which is undersired - and on many file systems (ext4, btrfs, jfs,
xfs, ..., but not reiserfs) fail with error EOPNOTSUPP - which is
misleading. Therefore test for a symbolic link explicitly.
Use fstatat because fstat does not work on O_PATH descriptors
before Linux 3.6. */
if (fstatat (fd, "", &st, AT_EMPTY_PATH) != 0)
{
int stat_errno = errno;
close (fd);
errno = stat_errno;
return -1;
}
if (S_ISLNK (st.st_mode))
{
close (fd);
errno = EOPNOTSUPP;
return -1;
}
static char const fmt[] = "/proc/self/fd/%d";
char buf[sizeof fmt - sizeof "%d" + INT_BUFSIZE_BOUND (int)];
sprintf (buf, fmt, fd);
int chmod_result = chmod (buf, mode);
int chmod_errno = errno;
close (fd);
if (chmod_result == 0)
return chmod_result;
if (chmod_errno != ENOENT)
{
errno = chmod_errno;
return chmod_result;
}
/* /proc is not mounted. */
/* Fall back on orig_fchmodat, despite the race. */
return orig_fchmodat (dir, file, mode, 0);
# elif (defined __linux__ || defined __ANDROID__) || !HAVE_LCHMOD
int fstatat_result = fstatat (dir, file, &st, AT_SYMLINK_NOFOLLOW);
if (fstatat_result != 0)
return fstatat_result;
if (S_ISLNK (st.st_mode))
{
errno = EOPNOTSUPP;
return -1;
}
/* Fall back on orig_fchmodat, despite the race. */
return orig_fchmodat (dir, file, mode, 0);
# else
return orig_fchmodat (dir, file, mode, 0);
# endif
}
# endif
return orig_fchmodat (dir, file, mode, flags);
}
#else
# define AT_FUNC_NAME fchmodat
# define AT_FUNC_F1 lchmod
# define AT_FUNC_F2 chmod
# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
# define AT_FUNC_POST_FILE_PARAM_DECLS , mode_t mode, int flag
# define AT_FUNC_POST_FILE_ARGS , mode
# include "at-func.c"
#endif
|