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/* Change the ownership and mode bits of a directory.
Copyright (C) 2006-2023 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 Paul Eggert. */
#include <config.h>
#include "dirchownmod.h"
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "stat-macros.h"
#ifndef HAVE_FCHMOD
# define HAVE_FCHMOD 0
# undef fchmod
# define fchmod(fd, mode) (-1)
#endif
/* Change the ownership and mode bits of a directory. If FD is
nonnegative, it should be a file descriptor associated with the
directory; close it before returning. DIR is the name of the
directory.
If MKDIR_MODE is not (mode_t) -1, mkdir (DIR, MKDIR_MODE) has just
been executed successfully with umask zero, so DIR should be a
directory (not a symbolic link).
First, set the file's owner to OWNER and group to GROUP, but leave
the owner alone if OWNER is (uid_t) -1, and similarly for GROUP.
Then, set the file's mode bits to MODE, except preserve any of the
bits that correspond to zero bits in MODE_BITS. In other words,
MODE_BITS is a mask that specifies which of the file's mode bits
should be set or cleared. MODE should be a subset of MODE_BITS,
which in turn should be a subset of CHMOD_MODE_BITS.
This implementation assumes the current umask is zero.
Return 0 if successful, -1 (setting errno) otherwise. Unsuccessful
calls may do the chown but not the chmod. */
int
dirchownmod (int fd, char const *dir, mode_t mkdir_mode,
uid_t owner, gid_t group,
mode_t mode, mode_t mode_bits)
{
struct stat st;
int result = (fd < 0 ? stat (dir, &st) : fstat (fd, &st));
if (result == 0)
{
mode_t dir_mode = st.st_mode;
/* Check whether DIR is a directory. If FD is nonnegative, this
check avoids changing the ownership and mode bits of the
wrong file in many cases. This doesn't fix all the race
conditions, but it is better than nothing. */
if (! S_ISDIR (dir_mode))
{
errno = ENOTDIR;
result = -1;
}
else
{
/* If at least one of the S_IXUGO bits are set, chown might
clear the S_ISUID and S_SGID bits. Keep track of any
file mode bits whose values are indeterminate due to this
issue. */
mode_t indeterminate = 0;
/* On some systems, chown clears S_ISUID and S_ISGID, so do
chown before chmod. On older System V hosts, ordinary
users can give their files away via chown; don't worry
about that here, since users shouldn't do that. */
if ((owner != (uid_t) -1 && owner != st.st_uid)
|| (group != (gid_t) -1 && group != st.st_gid))
{
result = (0 <= fd
? fchown (fd, owner, group)
: mkdir_mode != (mode_t) -1
? lchown (dir, owner, group)
: chown (dir, owner, group));
/* Either the user cares about an indeterminate bit and
it'll be set properly by chmod below, or the user
doesn't care and it's OK to use the bit's pre-chown
value. So there's no need to re-stat DIR here. */
if (result == 0 && (dir_mode & S_IXUGO))
indeterminate = dir_mode & (S_ISUID | S_ISGID);
}
/* If the file mode bits might not be right, use chmod to
change them. Don't change bits the user doesn't care
about. */
if (result == 0 && (((dir_mode ^ mode) | indeterminate) & mode_bits))
{
mode_t chmod_mode =
mode | (dir_mode & CHMOD_MODE_BITS & ~mode_bits);
result = (HAVE_FCHMOD && 0 <= fd
? fchmod (fd, chmod_mode)
: mkdir_mode != (mode_t) -1
? lchmod (dir, chmod_mode)
: chmod (dir, chmod_mode));
}
}
}
if (0 <= fd)
{
if (result == 0)
result = close (fd);
else
{
int e = errno;
close (fd);
errno = e;
}
}
return result;
}
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