1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1987, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#if defined(LIBC_SCCS) && !defined(lint)
33static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
34#endif /* LIBC_SCCS and not lint */
35#include <sys/cdefs.h>
36__FBSDID("$FreeBSD$");
37
38#include "namespace.h"
39#include <sys/param.h>
40#include <sys/stat.h>
41#include <fcntl.h>
42#include <errno.h>
43#include <stdio.h>
44#include <stdlib.h>
45#include <string.h>
46#include <ctype.h>
47#include <unistd.h>
48#include "un-namespace.h"
49
50char *_mktemp(char *);
51
52static int _gettemp(int, char *, int *, int, int, int);
53
54static const unsigned char padchar[] =
55"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
56
57int
58mkostempsat(int dfd, char *path, int slen, int oflags)
59{
60	int fd;
61
62	return (_gettemp(dfd, path, &fd, 0, slen, oflags) ? fd : -1);
63}
64
65int
66mkostemps(char *path, int slen, int oflags)
67{
68	int fd;
69
70	return (_gettemp(AT_FDCWD, path, &fd, 0, slen, oflags) ? fd : -1);
71}
72
73int
74mkstemps(char *path, int slen)
75{
76	int fd;
77
78	return (_gettemp(AT_FDCWD, path, &fd, 0, slen, 0) ? fd : -1);
79}
80
81int
82mkostemp(char *path, int oflags)
83{
84	int fd;
85
86	return (_gettemp(AT_FDCWD, path, &fd, 0, 0, oflags) ? fd : -1);
87}
88
89int
90mkstemp(char *path)
91{
92	int fd;
93
94	return (_gettemp(AT_FDCWD, path, &fd, 0, 0, 0) ? fd : -1);
95}
96
97char *
98mkdtemp(char *path)
99{
100	return (_gettemp(AT_FDCWD, path, (int *)NULL, 1, 0, 0) ? path : (char *)NULL);
101}
102
103char *
104_mktemp(char *path)
105{
106	return (_gettemp(AT_FDCWD, path, (int *)NULL, 0, 0, 0) ? path : (char *)NULL);
107}
108
109__warn_references(mktemp,
110    "warning: mktemp() possibly used unsafely; consider using mkstemp()");
111
112char *
113mktemp(char *path)
114{
115	return (_mktemp(path));
116}
117
118static int
119_gettemp(int dfd, char *path, int *doopen, int domkdir, int slen, int oflags)
120{
121	char *start, *trv, *suffp, *carryp;
122	char *pad;
123	struct stat sbuf;
124	int rval;
125	uint32_t rand;
126	char carrybuf[MAXPATHLEN];
127
128	if ((doopen != NULL && domkdir) || slen < 0 ||
129	    (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
130	    O_CLOEXEC)) != 0) {
131		errno = EINVAL;
132		return (0);
133	}
134
135	for (trv = path; *trv != '\0'; ++trv)
136		;
137	if (trv - path >= MAXPATHLEN) {
138		errno = ENAMETOOLONG;
139		return (0);
140	}
141	trv -= slen;
142	suffp = trv;
143	--trv;
144	if (trv < path || NULL != strchr(suffp, '/')) {
145		errno = EINVAL;
146		return (0);
147	}
148
149	/* Fill space with random characters */
150	while (trv >= path && *trv == 'X') {
151		rand = arc4random_uniform(sizeof(padchar) - 1);
152		*trv-- = padchar[rand];
153	}
154	start = trv + 1;
155
156	/* save first combination of random characters */
157	memcpy(carrybuf, start, suffp - start);
158
159	/*
160	 * check the target directory.
161	 */
162	if (doopen != NULL || domkdir) {
163		for (; trv > path; --trv) {
164			if (*trv == '/') {
165				*trv = '\0';
166				rval = fstatat(dfd, path, &sbuf, 0);
167				*trv = '/';
168				if (rval != 0)
169					return (0);
170				if (!S_ISDIR(sbuf.st_mode)) {
171					errno = ENOTDIR;
172					return (0);
173				}
174				break;
175			}
176		}
177	}
178
179	oflags |= O_CREAT | O_EXCL | O_RDWR;
180	for (;;) {
181		if (doopen) {
182			*doopen = _openat(dfd, path, oflags, 0600);
183			if (*doopen >= 0)
184				return (1);
185			if (errno != EEXIST)
186				return (0);
187		} else if (domkdir) {
188			if (mkdir(path, 0700) == 0)
189				return (1);
190			if (errno != EEXIST)
191				return (0);
192		} else if (lstat(path, &sbuf))
193			return (errno == ENOENT);
194
195		/* If we have a collision, cycle through the space of filenames */
196		for (trv = start, carryp = carrybuf;;) {
197			/* have we tried all possible permutations? */
198			if (trv == suffp)
199				return (0); /* yes - exit with EEXIST */
200			pad = strchr(padchar, *trv);
201			if (pad == NULL) {
202				/* this should never happen */
203				errno = EIO;
204				return (0);
205			}
206			/* increment character */
207			*trv = (*++pad == '\0') ? padchar[0] : *pad;
208			/* carry to next position? */
209			if (*trv == *carryp) {
210				/* increment position and loop */
211				++trv;
212				++carryp;
213			} else {
214				/* try with new name */
215				break;
216			}
217		}
218	}
219	/*NOTREACHED*/
220}
221