3 // Copyright (C) 2004 Enrico Scholz <enrico.scholz@informatik.tu-chemnitz.de>
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; version 2 of the License.
9 // This program is distributed in the hope that it will be useful,
10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 // GNU General Public License for more details.
14 // You should have received a copy of the GNU General Public License
15 // along with this program; if not, write to the Free Software
16 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
34 Unify_unify(char const *src, struct stat const UNUSED *src_stat,
35 char const *dst, bool ignore_zero)
37 size_t l = strlen(dst);
38 char tmpfile[l + sizeof(";XXXXXX")];
44 // at first, set the ILI flags on 'src'
47 VC_IATTR_IUNLINK|VC_IATTR_IMMUTABLE,
48 VC_IATTR_IUNLINK|VC_IATTR_IMMUTABLE)==-1)
51 lstat_succeeded = lstat(dst, &st)==0;
53 // check if 'dst' already exists
54 // when ignore_zero is true, do not make backups of empty destinations
55 if (lstat_succeeded && (st.st_size>0 || !ignore_zero)) {
56 // now, create a temporary filename
57 memcpy(tmpfile, dst, l);
58 memcpy(tmpfile+l, ";XXXXXX", 8);
59 fd = mkstemp(tmpfile);
67 // and rename the old file to this name
69 // NOTE: this rename() is race-free; when an attacker makes 'tmpfile' a
70 // directory, the operation would fail; when making it a symlink to a file
71 // or directory, the symlink but not the file/directory would be overridden
72 if (rename(dst, tmpfile)==-1) {
78 if (lstat_succeeded) unlink(dst);
82 // now, link the src-file to dst
83 if (link(src, dst)==-1) {
87 if (tmpfile[0]!='\0' &&
88 rename(tmpfile, dst)==-1) {
89 perror("FATAL error in rename()");
98 if (tmpfile[0]!='\0') {
99 int old_errno = errno;