1 /* provide consistent interface to chown for systems that don't interpret
2 an ID of -1 as meaning `don't change the corresponding ID'.
3 Copyright (C) 1997, 2004, 2005 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 Jim Meyering */
25 /* Disable the definition of chown to rpl_chown (from config.h) in this
26 file. Otherwise, we'd get conflicting prototypes for rpl_chown on
30 #include <sys/types.h>
38 /* Provide a more-closely POSIX-conforming version of chown on
39 systems with one or both of the following problems:
40 - chown doesn't treat an ID of -1 as meaning
41 `don't change the corresponding ID'.
42 - chown doesn't dereference symlinks. */
45 rpl_chown (const char *file, uid_t uid, gid_t gid)
47 #if CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE
48 if (gid == (gid_t) -1 || uid == (uid_t) -1)
50 struct stat file_stats;
52 /* Stat file to get id(s) that should remain unchanged. */
53 if (stat (file, &file_stats))
56 if (gid == (gid_t) -1)
57 gid = file_stats.st_gid;
59 if (uid == (uid_t) -1)
60 uid = file_stats.st_uid;
64 #if CHOWN_MODIFIES_SYMLINK
66 /* Handle the case in which the system-supplied chown function
67 does *not* follow symlinks. Instead, it changes permissions
68 on the symlink itself. To work around that, we open the
69 file (but this can fail due to lack of read or write permission) and
70 use fchown on the resulting descriptor. */
71 int fd = open (file, O_RDONLY | O_NONBLOCK | O_NOCTTY);
73 && (fd = open (file, O_WRONLY | O_NONBLOCK | O_NOCTTY)) < 0)
75 if (fchown (fd, uid, gid))
77 int saved_errno = errno;
85 return chown (file, uid, gid);