xref: /freebsd/lib/libc/stdio/mktemp.c (revision 0640d357f29fb1c0daaaffadd0416c5981413afd)
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 		"$Id: mktemp.c,v 1.11 1998/10/20 12:36:36 peter Exp $";
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));
54 
55 int
56 mkstemp(path)
57 	char *path;
58 {
59 	int fd;
60 
61 	return (_gettemp(path, &fd, 0) ? fd : -1);
62 }
63 
64 char *
65 mkdtemp(path)
66 	char *path;
67 {
68 	return(_gettemp(path, (int *)NULL, 1) ? path : (char *)NULL);
69 }
70 
71 char *
72 _mktemp(path)
73 	char *path;
74 {
75 	return(_gettemp(path, (int *)NULL, 0) ? path : (char *)NULL);
76 }
77 
78 #ifdef UNSAFE_WARN
79 __warn_references(mktemp,
80     "warning: mktemp() possibly used unsafely; consider using mkstemp()");
81 #endif
82 
83 char *
84 mktemp(path)
85 	char *path;
86 {
87 	return(_mktemp(path));
88 }
89 
90 static int
91 _gettemp(path, doopen, domkdir)
92 	char *path;
93 	register int *doopen;
94 	int domkdir;
95 {
96 	register char *start, *trv;
97 	struct stat sbuf;
98 	int pid, rval;
99 
100 	if (doopen && domkdir) {
101 		errno = EINVAL;
102 		return(0);
103 	}
104 
105 	pid = getpid();
106 	for (trv = path; *trv; ++trv)
107 		;
108 	--trv;
109 	while (*trv == 'X' && pid != 0) {
110 		*trv-- = (pid % 10) + '0';
111 		pid /= 10;
112 	}
113 	while (*trv == 'X') {
114 		char c;
115 
116 		pid = (arc4random() & 0xffff) % (26+26);
117 		if (pid < 26)
118 			c = pid + 'A';
119 		else
120 			c = (pid - 26) + 'a';
121 		*trv-- = c;
122 	}
123 	start = trv + 1;
124 
125 	/*
126 	 * check the target directory; if you have six X's and it
127 	 * doesn't exist this runs for a *very* long time.
128 	 */
129 	if (doopen || domkdir) {
130 		for (;; --trv) {
131 			if (trv <= path)
132 				break;
133 			if (*trv == '/') {
134 				*trv = '\0';
135 				rval = stat(path, &sbuf);
136 				*trv = '/';
137 				if (rval != 0)
138 					return(0);
139 				if (!S_ISDIR(sbuf.st_mode)) {
140 					errno = ENOTDIR;
141 					return(0);
142 				}
143 				break;
144 			}
145 		}
146 	}
147 
148 	for (;;) {
149 		if (doopen) {
150 			if ((*doopen =
151 			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
152 				return(1);
153 			if (errno != EEXIST)
154 				return(0);
155 		} else if (domkdir) {
156 			if (mkdir(path, 0700) == 0)
157 				return(1);
158 			if (errno != EEXIST)
159 				return(0);
160 		} else if (lstat(path, &sbuf))
161 			return(errno == ENOENT ? 1 : 0);
162 
163 		/* tricky little algorithm for backward compatibility */
164 		for (trv = start;;) {
165 			if (!*trv)
166 				return(0);
167 			if (*trv == 'Z')
168 				*trv++ = 'a';
169 			else {
170 				if (isdigit(*trv))
171 					*trv = 'a';
172 				else if (*trv == 'z')	/* inc from z to A */
173 					*trv = 'A';
174 				else
175 					++*trv;
176 				break;
177 			}
178 		}
179 	}
180 	/*NOTREACHED*/
181 }
182