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 #include "namespace.h"
33 #include <sys/param.h>
34 #include <sys/stat.h>
35 #include <fcntl.h>
36 #include <errno.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <ctype.h>
41 #include <unistd.h>
42 #include "un-namespace.h"
43
44 char *_mktemp(char *);
45
46 static int _gettemp(int, char *, int *, int, int, int);
47
48 static const unsigned char padchar[] =
49 "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
50
51 int
mkostempsat(int dfd,char * path,int slen,int oflags)52 mkostempsat(int dfd, char *path, int slen, int oflags)
53 {
54 int fd;
55
56 return (_gettemp(dfd, path, &fd, 0, slen, oflags) ? fd : -1);
57 }
58
59 int
mkostemps(char * path,int slen,int oflags)60 mkostemps(char *path, int slen, int oflags)
61 {
62 int fd;
63
64 return (_gettemp(AT_FDCWD, path, &fd, 0, slen, oflags) ? fd : -1);
65 }
66
67 int
mkstemps(char * path,int slen)68 mkstemps(char *path, int slen)
69 {
70 int fd;
71
72 return (_gettemp(AT_FDCWD, path, &fd, 0, slen, 0) ? fd : -1);
73 }
74
75 int
mkostemp(char * path,int oflags)76 mkostemp(char *path, int oflags)
77 {
78 int fd;
79
80 return (_gettemp(AT_FDCWD, path, &fd, 0, 0, oflags) ? fd : -1);
81 }
82
83 int
mkstemp(char * path)84 mkstemp(char *path)
85 {
86 int fd;
87
88 return (_gettemp(AT_FDCWD, path, &fd, 0, 0, 0) ? fd : -1);
89 }
90
91 char *
mkdtemp(char * path)92 mkdtemp(char *path)
93 {
94 return (_gettemp(AT_FDCWD, path, (int *)NULL, 1, 0, 0) ? path : (char *)NULL);
95 }
96
97 char *
_mktemp(char * path)98 _mktemp(char *path)
99 {
100 return (_gettemp(AT_FDCWD, path, (int *)NULL, 0, 0, 0) ? path : (char *)NULL);
101 }
102
103 __warn_references(mktemp,
104 "warning: mktemp() possibly used unsafely; consider using mkstemp()");
105
106 char *
mktemp(char * path)107 mktemp(char *path)
108 {
109 return (_mktemp(path));
110 }
111
112 static int
_gettemp(int dfd,char * path,int * doopen,int domkdir,int slen,int oflags)113 _gettemp(int dfd, char *path, int *doopen, int domkdir, int slen, int oflags)
114 {
115 char *start, *trv, *suffp, *carryp;
116 char *pad;
117 struct stat sbuf;
118 uint32_t rand;
119 char carrybuf[MAXPATHLEN];
120 int saved;
121
122 if ((doopen != NULL && domkdir) || slen < 0 ||
123 (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
124 O_CLOEXEC)) != 0) {
125 errno = EINVAL;
126 return (0);
127 }
128
129 trv = path + strlen(path);
130 if (trv - path >= MAXPATHLEN) {
131 errno = ENAMETOOLONG;
132 return (0);
133 }
134 trv -= slen;
135 suffp = trv;
136 --trv;
137 if (trv < path || NULL != strchr(suffp, '/')) {
138 errno = EINVAL;
139 return (0);
140 }
141
142 /* Fill space with random characters */
143 while (trv >= path && *trv == 'X') {
144 rand = arc4random_uniform(sizeof(padchar) - 1);
145 *trv-- = padchar[rand];
146 }
147 start = trv + 1;
148
149 saved = 0;
150 oflags |= O_CREAT | O_EXCL | O_RDWR;
151 for (;;) {
152 if (doopen) {
153 *doopen = _openat(dfd, path, oflags, 0600);
154 if (*doopen >= 0)
155 return (1);
156 if (errno != EEXIST)
157 return (0);
158 } else if (domkdir) {
159 if (mkdir(path, 0700) == 0)
160 return (1);
161 if (errno != EEXIST)
162 return (0);
163 } else if (lstat(path, &sbuf))
164 return (errno == ENOENT);
165
166 /* save first combination of random characters */
167 if (!saved) {
168 memcpy(carrybuf, start, suffp - start);
169 saved = 1;
170 }
171
172 /* If we have a collision, cycle through the space of filenames */
173 for (trv = start, carryp = carrybuf;;) {
174 /* have we tried all possible permutations? */
175 if (trv == suffp)
176 return (0); /* yes - exit with EEXIST */
177 pad = strchr(padchar, *trv);
178 if (pad == NULL) {
179 /* this should never happen */
180 errno = EIO;
181 return (0);
182 }
183 /* increment character */
184 *trv = (*++pad == '\0') ? padchar[0] : *pad;
185 /* carry to next position? */
186 if (*trv == *carryp) {
187 /* increment position and loop */
188 ++trv;
189 ++carryp;
190 } else {
191 /* try with new name */
192 break;
193 }
194 }
195 }
196 /*NOTREACHED*/
197 }
198