/* 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 */