1 /* Change the ownership and mode bits of a directory.
3 Copyright (C) 2006 Free Software Foundation, Inc.
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 2, or (at your option)
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.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19 /* Written by Paul Eggert. */
25 #include "dirchownmod.h"
28 #include <sys/types.h>
34 #include "stat-macros.h"
37 # define O_DIRECTORY 0
44 # define HAVE_FCHMOD 0
46 # define fchmod(fd, mode) (-1)
49 /* Change the ownership and mode bits of the directory DIR.
51 If MKDIR_MODE is not (mode_t) -1, mkdir (DIR, MKDIR_MODE) has just
52 been executed successfully with umask zero, so DIR should be a
53 directory (not a symbolic link).
55 First, set the file's owner to OWNER and group to GROUP, but leave
56 the owner alone if OWNER is (uid_t) -1, and similarly for GROUP.
58 Then, set the file's mode bits to MODE, except preserve any of the
59 bits that correspond to zero bits in MODE_BITS. In other words,
60 MODE_BITS is a mask that specifies which of the file's mode bits
61 should be set or cleared. MODE should be a subset of MODE_BITS,
62 which in turn should be a subset of CHMOD_MODE_BITS.
64 This implementation assumes the current umask is zero.
66 Return 0 if successful, -1 (setting errno) otherwise. Unsuccessful
67 calls may do the chown but not the chmod. */
70 dirchownmod (char const *dir, mode_t mkdir_mode,
71 uid_t owner, gid_t group,
72 mode_t mode, mode_t mode_bits)
77 /* Manipulate DIR via a file descriptor if possible, to avoid some races. */
78 int open_flags = O_RDONLY | O_DIRECTORY | O_NOCTTY | O_NOFOLLOW | O_NONBLOCK;
79 int fd = open (dir, open_flags);
81 /* Fail if the directory is unreadable, the directory previously
82 existed or was created without read permission. Otherwise, get
85 result = fstat (fd, &st);
86 else if (errno != EACCES
87 || (mkdir_mode != (mode_t) -1 && mkdir_mode & S_IRUSR))
90 result = stat (dir, &st);
94 mode_t dir_mode = st.st_mode;
96 /* Check whether DIR is a directory. If FD is nonnegative, this
97 check avoids changing the ownership and mode bits of the
98 wrong file in many cases. This doesn't fix all the race
99 conditions, but it is better than nothing. */
100 if (! S_ISDIR (dir_mode))
107 /* If at least one of the S_IXUGO bits are set, chown might
108 clear the S_ISUID and S_SGID bits. Keep track of any
109 file mode bits whose values are indeterminate due to this
111 mode_t indeterminate = 0;
113 /* On some systems, chown clears S_ISUID and S_ISGID, so do
114 chown before chmod. On older System V hosts, ordinary
115 users can give their files away via chown; don't worry
116 about that here, since users shouldn't do that. */
118 if ((owner != (uid_t) -1 && owner != st.st_uid)
119 || (group != (gid_t) -1 && group != st.st_gid))
122 ? fchown (fd, owner, group)
123 : mkdir_mode != (mode_t) -1
124 ? lchown (dir, owner, group)
125 : chown (dir, owner, group));
127 /* Either the user cares about an indeterminate bit and
128 it'll be set properly by chmod below, or the user
129 doesn't care and it's OK to use the bit's pre-chown
130 value. So there's no need to re-stat DIR here. */
132 if (result == 0 && (dir_mode & S_IXUGO))
133 indeterminate = dir_mode & (S_ISUID | S_ISGID);
136 /* If the file mode bits might not be right, use chmod to
137 change them. Don't change bits the user doesn't care
139 if (result == 0 && (((dir_mode ^ mode) | indeterminate) & mode_bits))
142 mode | (dir_mode & CHMOD_MODE_BITS & ~mode_bits);
143 result = (HAVE_FCHMOD && 0 <= fd
144 ? fchmod (fd, chmod_mode)
145 : mkdir_mode != (mode_t) -1
146 ? lchmod (dir, chmod_mode)
147 : chmod (dir, chmod_mode));