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)
33 static char sccsid[] = "@(#)mktemp.c 8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 #include "namespace.h"
37 #include <sys/param.h>
38 #include <sys/stat.h>
39 #include <fcntl.h>
40 #include <errno.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <ctype.h>
45 #include <unistd.h>
46 #include "un-namespace.h"
47
48 char *_mktemp(char *);
49
50 static int _gettemp(int, char *, int *, int, int, int);
51
52 static const unsigned char padchar[] =
53 "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
54
55 int
mkostempsat(int dfd,char * path,int slen,int oflags)56 mkostempsat(int dfd, char *path, int slen, int oflags)
57 {
58 int fd;
59
60 return (_gettemp(dfd, path, &fd, 0, slen, oflags) ? fd : -1);
61 }
62
63 int
mkostemps(char * path,int slen,int oflags)64 mkostemps(char *path, int slen, int oflags)
65 {
66 int fd;
67
68 return (_gettemp(AT_FDCWD, path, &fd, 0, slen, oflags) ? fd : -1);
69 }
70
71 int
mkstemps(char * path,int slen)72 mkstemps(char *path, int slen)
73 {
74 int fd;
75
76 return (_gettemp(AT_FDCWD, path, &fd, 0, slen, 0) ? fd : -1);
77 }
78
79 int
mkostemp(char * path,int oflags)80 mkostemp(char *path, int oflags)
81 {
82 int fd;
83
84 return (_gettemp(AT_FDCWD, path, &fd, 0, 0, oflags) ? fd : -1);
85 }
86
87 int
mkstemp(char * path)88 mkstemp(char *path)
89 {
90 int fd;
91
92 return (_gettemp(AT_FDCWD, path, &fd, 0, 0, 0) ? fd : -1);
93 }
94
95 char *
mkdtemp(char * path)96 mkdtemp(char *path)
97 {
98 return (_gettemp(AT_FDCWD, path, (int *)NULL, 1, 0, 0) ? path : (char *)NULL);
99 }
100
101 char *
_mktemp(char * path)102 _mktemp(char *path)
103 {
104 return (_gettemp(AT_FDCWD, path, (int *)NULL, 0, 0, 0) ? path : (char *)NULL);
105 }
106
107 __warn_references(mktemp,
108 "warning: mktemp() possibly used unsafely; consider using mkstemp()");
109
110 char *
mktemp(char * path)111 mktemp(char *path)
112 {
113 return (_mktemp(path));
114 }
115
116 static int
_gettemp(int dfd,char * path,int * doopen,int domkdir,int slen,int oflags)117 _gettemp(int dfd, char *path, int *doopen, int domkdir, int slen, int oflags)
118 {
119 char *start, *trv, *suffp, *carryp;
120 char *pad;
121 struct stat sbuf;
122 uint32_t rand;
123 char carrybuf[MAXPATHLEN];
124 int saved;
125
126 if ((doopen != NULL && domkdir) || slen < 0 ||
127 (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
128 O_CLOEXEC)) != 0) {
129 errno = EINVAL;
130 return (0);
131 }
132
133 trv = path + strlen(path);
134 if (trv - path >= MAXPATHLEN) {
135 errno = ENAMETOOLONG;
136 return (0);
137 }
138 trv -= slen;
139 suffp = trv;
140 --trv;
141 if (trv < path || NULL != strchr(suffp, '/')) {
142 errno = EINVAL;
143 return (0);
144 }
145
146 /* Fill space with random characters */
147 while (trv >= path && *trv == 'X') {
148 rand = arc4random_uniform(sizeof(padchar) - 1);
149 *trv-- = padchar[rand];
150 }
151 start = trv + 1;
152
153 saved = 0;
154 oflags |= O_CREAT | O_EXCL | O_RDWR;
155 for (;;) {
156 if (doopen) {
157 *doopen = _openat(dfd, path, oflags, 0600);
158 if (*doopen >= 0)
159 return (1);
160 if (errno != EEXIST)
161 return (0);
162 } else if (domkdir) {
163 if (mkdir(path, 0700) == 0)
164 return (1);
165 if (errno != EEXIST)
166 return (0);
167 } else if (lstat(path, &sbuf))
168 return (errno == ENOENT);
169
170 /* save first combination of random characters */
171 if (!saved) {
172 memcpy(carrybuf, start, suffp - start);
173 saved = 1;
174 }
175
176 /* If we have a collision, cycle through the space of filenames */
177 for (trv = start, carryp = carrybuf;;) {
178 /* have we tried all possible permutations? */
179 if (trv == suffp)
180 return (0); /* yes - exit with EEXIST */
181 pad = strchr(padchar, *trv);
182 if (pad == NULL) {
183 /* this should never happen */
184 errno = EIO;
185 return (0);
186 }
187 /* increment character */
188 *trv = (*++pad == '\0') ? padchar[0] : *pad;
189 /* carry to next position? */
190 if (*trv == *carryp) {
191 /* increment position and loop */
192 ++trv;
193 ++carryp;
194 } else {
195 /* try with new name */
196 break;
197 }
198 }
199 }
200 /*NOTREACHED*/
201 }
202