1/* $Id: compat_mkstemps.c,v 1.1 2021/09/19 15:05:39 schwarze Exp $ */
2/*
3 * Copyright (c) 2015, 2021 Ingo Schwarze <schwarze@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 *
17 * Parts of the algorithm of this function are inspired by OpenBSD
18 * mkdtemp(3) by Theo de Raadt and Todd Miller, but the code differs.
19 */
20#include "config.h"
21
22#include <sys/stat.h>
23#include <errno.h>
24#include <fcntl.h>
25#include <limits.h>
26#include <stdlib.h>
27#include <string.h>
28
29int
30mkstemps(char *path, int suffixlen)
31{
32	char	*start, *end, *cp;
33	int	 fd, tries;
34	char	 backup;
35
36	end = strchr(path, '\0');
37	if (suffixlen < 0 || suffixlen > end - path - 6) {
38		errno = EINVAL;
39		return -1;
40	}
41	end -= suffixlen;
42	for (start = end; start > path; start--)
43		if (start[-1] != 'X')
44			break;
45
46	backup = *end;
47	for (tries = INT_MAX; tries; tries--) {
48		*end = '\0';
49		cp = mktemp(path);
50		*end = backup;
51		if (cp == NULL)
52			return -1;
53		fd = open(path, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR);
54		if (fd != -1)
55			return fd;
56		for (cp = start; cp < end; cp++)
57			*cp = 'X';
58		if (errno != EEXIST)
59			return -1;
60	}
61	errno = EEXIST;
62	return -1;
63}
64