xref: /freebsd/lib/libc/stdio/mktemp.c (revision daf1cffce2e07931f27c6c6998652e90df6ba87e)
1 /*
2  * Copyright (c) 1987, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if defined(LIBC_SCCS) && !defined(lint)
35 #if 0
36 static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
37 #endif
38 static const char rcsid[] =
39   "$FreeBSD$";
40 #endif /* LIBC_SCCS and not lint */
41 
42 #include <sys/types.h>
43 #include <sys/stat.h>
44 #include <fcntl.h>
45 #include <errno.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <ctype.h>
49 #include <unistd.h>
50 
51 char *_mktemp __P((char *));
52 
53 static int _gettemp __P((char *, int *, int, int));
54 
55 int
56 mkstemps(path, slen)
57 	char *path;
58 	int slen;
59 {
60 	int fd;
61 
62 	return (_gettemp(path, &fd, 0, slen) ? fd : -1);
63 }
64 
65 int
66 mkstemp(path)
67 	char *path;
68 {
69 	int fd;
70 
71 	return (_gettemp(path, &fd, 0, 0) ? fd : -1);
72 }
73 
74 char *
75 mkdtemp(path)
76 	char *path;
77 {
78 	return(_gettemp(path, (int *)NULL, 1, 0) ? path : (char *)NULL);
79 }
80 
81 char *
82 _mktemp(path)
83 	char *path;
84 {
85 	return(_gettemp(path, (int *)NULL, 0, 0) ? path : (char *)NULL);
86 }
87 
88 __warn_references(mktemp,
89     "warning: mktemp() possibly used unsafely; consider using mkstemp()");
90 
91 char *
92 mktemp(path)
93 	char *path;
94 {
95 	return(_mktemp(path));
96 }
97 
98 static int
99 _gettemp(path, doopen, domkdir, slen)
100 	char *path;
101 	register int *doopen;
102 	int domkdir;
103 	int slen;
104 {
105 	register char *start, *trv, *suffp;
106 	struct stat sbuf;
107 	int pid, rval;
108 
109 	if (doopen && domkdir) {
110 		errno = EINVAL;
111 		return(0);
112 	}
113 
114 	for (trv = path; *trv; ++trv)
115 		;
116 	trv -= slen;
117 	suffp = trv;
118 	--trv;
119 	if (trv < path) {
120 		errno = EINVAL;
121 		return (0);
122 	}
123 	pid = getpid();
124 	while (*trv == 'X' && pid != 0) {
125 		*trv-- = (pid % 10) + '0';
126 		pid /= 10;
127 	}
128 	while (*trv == 'X') {
129 		char c;
130 
131 		pid = (arc4random() & 0xffff) % (26+26);
132 		if (pid < 26)
133 			c = pid + 'A';
134 		else
135 			c = (pid - 26) + 'a';
136 		*trv-- = c;
137 	}
138 	start = trv + 1;
139 
140 	/*
141 	 * check the target directory; if you have six X's and it
142 	 * doesn't exist this runs for a *very* long time.
143 	 */
144 	if (doopen || domkdir) {
145 		for (;; --trv) {
146 			if (trv <= path)
147 				break;
148 			if (*trv == '/') {
149 				*trv = '\0';
150 				rval = stat(path, &sbuf);
151 				*trv = '/';
152 				if (rval != 0)
153 					return(0);
154 				if (!S_ISDIR(sbuf.st_mode)) {
155 					errno = ENOTDIR;
156 					return(0);
157 				}
158 				break;
159 			}
160 		}
161 	}
162 
163 	for (;;) {
164 		if (doopen) {
165 			if ((*doopen =
166 			    _open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
167 				return(1);
168 			if (errno != EEXIST)
169 				return(0);
170 		} else if (domkdir) {
171 			if (mkdir(path, 0700) == 0)
172 				return(1);
173 			if (errno != EEXIST)
174 				return(0);
175 		} else if (lstat(path, &sbuf))
176 			return(errno == ENOENT ? 1 : 0);
177 
178 		/* tricky little algorithm for backward compatibility */
179 		for (trv = start;;) {
180 			if (*trv == '\0' || trv == suffp)
181 				return(0);
182 			if (*trv == 'Z')
183 				*trv++ = 'a';
184 			else {
185 				if (isdigit((unsigned char)*trv))
186 					*trv = 'a';
187 				else if (*trv == 'z')	/* inc from z to A */
188 					*trv = 'A';
189 				else
190 					++*trv;
191 				break;
192 			}
193 		}
194 	}
195 	/*NOTREACHED*/
196 }
197