mktemp.c revision 330897 
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: stable/11/lib/libc/stdio/mktemp.c 330897 2018-03-14 03:19:51Z eadler $");
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(char *, int *, int, int, int);
53
54static const unsigned char padchar[] =
55"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
56
57int
58mkostemps(char *path, int slen, int oflags)
59{
60	int fd;
61
62	return (_gettemp(path, &fd, 0, slen, oflags) ? fd : -1);
63}
64
65int
66mkstemps(char *path, int slen)
67{
68	int fd;
69
70	return (_gettemp(path, &fd, 0, slen, 0) ? fd : -1);
71}
72
73int
74mkostemp(char *path, int oflags)
75{
76	int fd;
77
78	return (_gettemp(path, &fd, 0, 0, oflags) ? fd : -1);
79}
80
81int
82mkstemp(char *path)
83{
84	int fd;
85
86	return (_gettemp(path, &fd, 0, 0, 0) ? fd : -1);
87}
88
89char *
90mkdtemp(char *path)
91{
92	return (_gettemp(path, (int *)NULL, 1, 0, 0) ? path : (char *)NULL);
93}
94
95char *
96_mktemp(char *path)
97{
98	return (_gettemp(path, (int *)NULL, 0, 0, 0) ? path : (char *)NULL);
99}
100
101__warn_references(mktemp,
102    "warning: mktemp() possibly used unsafely; consider using mkstemp()");
103
104char *
105mktemp(char *path)
106{
107	return (_mktemp(path));
108}
109
110static int
111_gettemp(char *path, int *doopen, int domkdir, int slen, int oflags)
112{
113	char *start, *trv, *suffp, *carryp;
114	char *pad;
115	struct stat sbuf;
116	int rval;
117	uint32_t rand;
118	char carrybuf[MAXPATHLEN];
119
120	if ((doopen != NULL && domkdir) || slen < 0 ||
121	    (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
122	    O_CLOEXEC)) != 0) {
123		errno = EINVAL;
124		return (0);
125	}
126
127	for (trv = path; *trv != '\0'; ++trv)
128		;
129	if (trv - path >= MAXPATHLEN) {
130		errno = ENAMETOOLONG;
131		return (0);
132	}
133	trv -= slen;
134	suffp = trv;
135	--trv;
136	if (trv < path || NULL != strchr(suffp, '/')) {
137		errno = EINVAL;
138		return (0);
139	}
140
141	/* Fill space with random characters */
142	while (trv >= path && *trv == 'X') {
143		rand = arc4random_uniform(sizeof(padchar) - 1);
144		*trv-- = padchar[rand];
145	}
146	start = trv + 1;
147
148	/* save first combination of random characters */
149	memcpy(carrybuf, start, suffp - start);
150
151	/*
152	 * check the target directory.
153	 */
154	if (doopen != NULL || domkdir) {
155		for (; trv > path; --trv) {
156			if (*trv == '/') {
157				*trv = '\0';
158				rval = stat(path, &sbuf);
159				*trv = '/';
160				if (rval != 0)
161					return (0);
162				if (!S_ISDIR(sbuf.st_mode)) {
163					errno = ENOTDIR;
164					return (0);
165				}
166				break;
167			}
168		}
169	}
170
171	for (;;) {
172		if (doopen) {
173			if ((*doopen =
174			    _open(path, O_CREAT|O_EXCL|O_RDWR|oflags, 0600)) >=
175			    0)
176				return (1);
177			if (errno != EEXIST)
178				return (0);
179		} else if (domkdir) {
180			if (mkdir(path, 0700) == 0)
181				return (1);
182			if (errno != EEXIST)
183				return (0);
184		} else if (lstat(path, &sbuf))
185			return (errno == ENOENT);
186
187		/* If we have a collision, cycle through the space of filenames */
188		for (trv = start, carryp = carrybuf;;) {
189			/* have we tried all possible permutations? */
190			if (trv == suffp)
191				return (0); /* yes - exit with EEXIST */
192			pad = strchr(padchar, *trv);
193			if (pad == NULL) {
194				/* this should never happen */
195				errno = EIO;
196				return (0);
197			}
198			/* increment character */
199			*trv = (*++pad == '\0') ? padchar[0] : *pad;
200			/* carry to next position? */
201			if (*trv == *carryp) {
202				/* increment position and loop */
203				++trv;
204				++carryp;
205			} else {
206				/* try with new name */
207				break;
208			}
209		}
210	}
211	/*NOTREACHED*/
212}
213