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.
35 Unify_unify(char const *src, struct stat const UNUSED *src_stat,
36 char const *dst, bool ignore_zero)
38 size_t l = strlen(dst);
39 char tmpfile[l + sizeof(";XXXXXX")];
44 sigset_t mask_new, mask_old;
47 // at first, set the ILI flags on 'src'
50 VC_IATTR_IUNLINK|VC_IATTR_IMMUTABLE,
51 VC_IATTR_IUNLINK|VC_IATTR_IMMUTABLE)==-1) {
52 perror("vc_set_iattr()");
56 lstat_succeeded = lstat(dst, &st)==0;
58 sigfillset(&mask_new);
59 if (sigprocmask(SIG_SETMASK, &mask_new, &mask_old)==-1) {
60 perror("sigprocmask()");
65 // check if 'dst' already exists
66 // when ignore_zero is true, do not make backups of empty destinations
67 if (lstat_succeeded && (st.st_size>0 || !ignore_zero)) {
68 // now, create a temporary filename
69 memcpy(tmpfile, dst, l);
70 memcpy(tmpfile+l, ";XXXXXX", 8);
71 fd = mkstemp(tmpfile);
80 // and rename the old file to this name
82 // NOTE: this rename() is race-free; when an attacker makes 'tmpfile' a
83 // directory, the operation would fail; when making it a symlink to a file
84 // or directory, the symlink but not the file/directory would be overridden
85 if (rename(dst, tmpfile)==-1) {
91 if (lstat_succeeded) unlink(dst);
95 // now, link the src-file to dst
96 if (link(src, dst)==-1) {
100 if (tmpfile[0]!='\0' &&
101 rename(tmpfile, dst)==-1) {
102 perror("FATAL error in rename()");
113 if (tmpfile[0]!='\0')
116 if (sigprocmask(SIG_SETMASK, &mask_old, 0)==-1)
117 perror("sigprocmask()");