xref: /freebsd/lib/libc/stdio/mktemp.c (revision a1a4f1a0d87b594d3f17a97dc0127eec1417e6f6)
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 #ifdef UNSAFE_WARN
89 __warn_references(mktemp,
90     "warning: mktemp() possibly used unsafely; consider using mkstemp()");
91 #endif
92 
93 char *
94 mktemp(path)
95 	char *path;
96 {
97 	return(_mktemp(path));
98 }
99 
100 static int
101 _gettemp(path, doopen, domkdir, slen)
102 	char *path;
103 	register int *doopen;
104 	int domkdir;
105 	int slen;
106 {
107 	register char *start, *trv, *suffp;
108 	struct stat sbuf;
109 	int pid, rval;
110 
111 	if (doopen && domkdir) {
112 		errno = EINVAL;
113 		return(0);
114 	}
115 
116 	pid = getpid();
117 	for (trv = path; *trv; ++trv)
118 		;
119 	trv -= slen;
120 	suffp = trv;
121 	--trv;
122 	if (trv < path) {
123 		errno = EINVAL;
124 		return (0);
125 	}
126 	while (*trv == 'X' && pid != 0) {
127 		*trv-- = (pid % 10) + '0';
128 		pid /= 10;
129 	}
130 	while (*trv == 'X') {
131 		char c;
132 
133 		pid = (arc4random() & 0xffff) % (26+26);
134 		if (pid < 26)
135 			c = pid + 'A';
136 		else
137 			c = (pid - 26) + 'a';
138 		*trv-- = c;
139 	}
140 	start = trv + 1;
141 
142 	/*
143 	 * check the target directory; if you have six X's and it
144 	 * doesn't exist this runs for a *very* long time.
145 	 */
146 	if (doopen || domkdir) {
147 		for (;; --trv) {
148 			if (trv <= path)
149 				break;
150 			if (*trv == '/') {
151 				*trv = '\0';
152 				rval = stat(path, &sbuf);
153 				*trv = '/';
154 				if (rval != 0)
155 					return(0);
156 				if (!S_ISDIR(sbuf.st_mode)) {
157 					errno = ENOTDIR;
158 					return(0);
159 				}
160 				break;
161 			}
162 		}
163 	}
164 
165 	for (;;) {
166 		if (doopen) {
167 			if ((*doopen =
168 			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
169 				return(1);
170 			if (errno != EEXIST)
171 				return(0);
172 		} else if (domkdir) {
173 			if (mkdir(path, 0700) == 0)
174 				return(1);
175 			if (errno != EEXIST)
176 				return(0);
177 		} else if (lstat(path, &sbuf))
178 			return(errno == ENOENT ? 1 : 0);
179 
180 		/* tricky little algorithm for backward compatibility */
181 		for (trv = start;;) {
182 			if (!*trv)
183 				return(0);
184 			if (*trv == 'Z')
185 				*trv++ = 'a';
186 			else {
187 				if (isdigit(*trv))
188 					*trv = 'a';
189 				else if (*trv == 'z')	/* inc from z to A */
190 					*trv = 'A';
191 				else
192 					++*trv;
193 				break;
194 			}
195 		}
196 	}
197 	/*NOTREACHED*/
198 }
199