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/* Provide a stub lchown function for systems that lack it.
Copyright (C) 1998-1999, 2002, 2004, 2006-2007, 2009-2024 Free Software
Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* written by Jim Meyering */
#include <config.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#if !HAVE_LCHOWN
/* If the system chown does not follow symlinks, we don't want it
replaced by gnulib's chown, which does follow symlinks. */
# if CHOWN_MODIFIES_SYMLINK /* native Windows and some very old platforms */
# undef chown
# endif
/* Work just like chown, except when FILE is a symbolic link.
In that case, set errno to EOPNOTSUPP and return -1.
But if autoconf tests determined that chown modifies
symlinks, then just call chown. */
int
lchown (const char *file, uid_t uid, gid_t gid)
{
# if HAVE_CHOWN
# if ! CHOWN_MODIFIES_SYMLINK
char readlink_buf[1];
if (0 <= readlink (file, readlink_buf, sizeof readlink_buf))
{
errno = EOPNOTSUPP;
return -1;
}
# endif
return chown (file, uid, gid);
# else /* !HAVE_CHOWN */
errno = ENOSYS;
return -1;
# endif
}
#else /* HAVE_LCHOWN */
# undef lchown
/* Work around trailing slash bugs in lchown. */
int
rpl_lchown (const char *file, uid_t uid, gid_t gid)
{
bool stat_valid = false;
int result;
# if CHOWN_CHANGE_TIME_BUG
struct stat st;
if (gid != (gid_t) -1 || uid != (uid_t) -1)
{
if (lstat (file, &st))
return -1;
stat_valid = true;
if (!S_ISLNK (st.st_mode))
return chown (file, uid, gid);
}
# endif
# if CHOWN_TRAILING_SLASH_BUG
if (!stat_valid)
{
size_t len = strlen (file);
if (len && file[len - 1] == '/')
return chown (file, uid, gid);
}
# endif
result = lchown (file, uid, gid);
# if CHOWN_CHANGE_TIME_BUG && HAVE_LCHMOD
if (result == 0 && stat_valid
&& (uid == st.st_uid || uid == (uid_t) -1)
&& (gid == st.st_gid || gid == (gid_t) -1))
{
/* No change in ownership, but at least one argument was not -1,
so we are required to update ctime. Since lchown succeeded,
we assume that lchmod will do likewise. But if the system
lacks lchmod and lutimes, we are out of luck. Oh well. */
result = lchmod (file, st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO
| S_ISUID | S_ISGID | S_ISVTX));
}
# endif
return result;
}
#endif /* HAVE_LCHOWN */
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