1 /* Change the ownership and mode bits of a directory.
2
3 Copyright (C) 2006-2014 Free Software Foundation, Inc.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program 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
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17
18 /* Written by Paul Eggert. */
19
20 #include <config.h>
21
22 #include "dirchownmod.h"
23
24 #include <errno.h>
25 #include <sys/types.h>
26 #include <sys/stat.h>
27 #include <unistd.h>
28
29 #include "stat-macros.h"
30
31 #ifndef HAVE_FCHMOD
32 # define HAVE_FCHMOD 0
33 # undef fchmod
34 # define fchmod(fd, mode) (-1)
35 #endif
36
37 /* Change the ownership and mode bits of a directory. If FD is
38 nonnegative, it should be a file descriptor associated with the
39 directory; close it before returning. DIR is the name of the
40 directory.
41
42 If MKDIR_MODE is not (mode_t) -1, mkdir (DIR, MKDIR_MODE) has just
43 been executed successfully with umask zero, so DIR should be a
44 directory (not a symbolic link).
45
46 First, set the file's owner to OWNER and group to GROUP, but leave
47 the owner alone if OWNER is (uid_t) -1, and similarly for GROUP.
48
49 Then, set the file's mode bits to MODE, except preserve any of the
50 bits that correspond to zero bits in MODE_BITS. In other words,
51 MODE_BITS is a mask that specifies which of the file's mode bits
52 should be set or cleared. MODE should be a subset of MODE_BITS,
53 which in turn should be a subset of CHMOD_MODE_BITS.
54
55 This implementation assumes the current umask is zero.
56
57 Return 0 if successful, -1 (setting errno) otherwise. Unsuccessful
58 calls may do the chown but not the chmod. */
59
60 int
dirchownmod(int fd,char const * dir,mode_t mkdir_mode,uid_t owner,gid_t group,mode_t mode,mode_t mode_bits)61 dirchownmod (int fd, char const *dir, mode_t mkdir_mode,
62 uid_t owner, gid_t group,
63 mode_t mode, mode_t mode_bits)
64 {
65 struct stat st;
66 int result = (fd < 0 ? stat (dir, &st) : fstat (fd, &st));
67
68 if (result == 0)
69 {
70 mode_t dir_mode = st.st_mode;
71
72 /* Check whether DIR is a directory. If FD is nonnegative, this
73 check avoids changing the ownership and mode bits of the
74 wrong file in many cases. This doesn't fix all the race
75 conditions, but it is better than nothing. */
76 if (! S_ISDIR (dir_mode))
77 {
78 errno = ENOTDIR;
79 result = -1;
80 }
81 else
82 {
83 /* If at least one of the S_IXUGO bits are set, chown might
84 clear the S_ISUID and S_SGID bits. Keep track of any
85 file mode bits whose values are indeterminate due to this
86 issue. */
87 mode_t indeterminate = 0;
88
89 /* On some systems, chown clears S_ISUID and S_ISGID, so do
90 chown before chmod. On older System V hosts, ordinary
91 users can give their files away via chown; don't worry
92 about that here, since users shouldn't do that. */
93
94 if ((owner != (uid_t) -1 && owner != st.st_uid)
95 || (group != (gid_t) -1 && group != st.st_gid))
96 {
97 result = (0 <= fd
98 ? fchown (fd, owner, group)
99 : mkdir_mode != (mode_t) -1
100 ? lchown (dir, owner, group)
101 : chown (dir, owner, group));
102
103 /* Either the user cares about an indeterminate bit and
104 it'll be set properly by chmod below, or the user
105 doesn't care and it's OK to use the bit's pre-chown
106 value. So there's no need to re-stat DIR here. */
107
108 if (result == 0 && (dir_mode & S_IXUGO))
109 indeterminate = dir_mode & (S_ISUID | S_ISGID);
110 }
111
112 /* If the file mode bits might not be right, use chmod to
113 change them. Don't change bits the user doesn't care
114 about. */
115 if (result == 0 && (((dir_mode ^ mode) | indeterminate) & mode_bits))
116 {
117 mode_t chmod_mode =
118 mode | (dir_mode & CHMOD_MODE_BITS & ~mode_bits);
119 result = (HAVE_FCHMOD && 0 <= fd
120 ? fchmod (fd, chmod_mode)
121 : mkdir_mode != (mode_t) -1
122 ? lchmod (dir, chmod_mode)
123 : chmod (dir, chmod_mode));
124 }
125 }
126 }
127
128 if (0 <= fd)
129 {
130 if (result == 0)
131 result = close (fd);
132 else
133 {
134 int e = errno;
135 close (fd);
136 errno = e;
137 }
138 }
139
140 return result;
141 }
142