1 /* $OpenBSD: mktemp.c,v 1.33 2014/05/06 22:55:27 millert Exp $ */
2 /*
3 * Copyright (c) 1996-1998, 2008 Theo de Raadt
4 * Copyright (c) 1997, 2008-2009 Todd C. Miller
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/types.h>
20 #include <sys/stat.h>
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <limits.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <ctype.h>
28 #include <unistd.h>
29
30 #define MKTEMP_NAME 0
31 #define MKTEMP_FILE 1
32 #define MKTEMP_DIR 2
33
34 #define TEMPCHARS "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
35 #define NUM_CHARS (sizeof(TEMPCHARS) - 1)
36 #define MIN_X 6
37
38 #ifndef nitems
39 #define nitems(_a) (sizeof((_a)) / sizeof((_a)[0]))
40 #endif
41
42 static int
mktemp_internal(char * path,int slen,int mode)43 mktemp_internal(char *path, int slen, int mode)
44 {
45 char *start, *cp, *ep;
46 const char *tempchars = TEMPCHARS;
47 unsigned int tries;
48 struct stat sb;
49 size_t len;
50 int fd;
51
52 len = strlen(path);
53 if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) {
54 errno = EINVAL;
55 return(-1);
56 }
57 ep = path + len - slen;
58
59 for (start = ep; start > path && start[-1] == 'X'; start--)
60 ;
61 if (ep - start < MIN_X) {
62 errno = EINVAL;
63 return(-1);
64 }
65
66 tries = INT_MAX;
67 do {
68 cp = start;
69 do {
70 unsigned short rbuf[16];
71 unsigned int i;
72
73 /*
74 * Avoid lots of arc4random() calls by using
75 * a buffer sized for up to 16 Xs at a time.
76 */
77 arc4random_buf(rbuf, sizeof(rbuf));
78 for (i = 0; i < nitems(rbuf) && cp != ep; i++)
79 *cp++ = tempchars[rbuf[i] % NUM_CHARS];
80 } while (cp != ep);
81
82 switch (mode) {
83 case MKTEMP_NAME:
84 if (lstat(path, &sb) != 0)
85 return(errno == ENOENT ? 0 : -1);
86 break;
87 case MKTEMP_FILE:
88 fd = open(path, O_CREAT|O_EXCL|O_RDWR, S_IRUSR|S_IWUSR);
89 if (fd != -1 || errno != EEXIST)
90 return(fd);
91 break;
92 case MKTEMP_DIR:
93 if (mkdir(path, S_IRUSR|S_IWUSR|S_IXUSR) == 0)
94 return(0);
95 if (errno != EEXIST)
96 return(-1);
97 break;
98 }
99 } while (--tries);
100
101 errno = EEXIST;
102 return(-1);
103 }
104
105 char *_mktemp(char *);
106
107 char *
_mktemp(char * path)108 _mktemp(char *path)
109 {
110 if (mktemp_internal(path, 0, MKTEMP_NAME) == -1)
111 return(NULL);
112 return(path);
113 }
114
115 __warn_references(mktemp,
116 "warning: mktemp() possibly used unsafely; consider using mkstemp()");
117
118 char *
mktemp(char * path)119 mktemp(char *path)
120 {
121 return(_mktemp(path));
122 }
123
124 int
mkstemp(char * path)125 mkstemp(char *path)
126 {
127 return(mktemp_internal(path, 0, MKTEMP_FILE));
128 }
129
130 int
mkstemps(char * path,int slen)131 mkstemps(char *path, int slen)
132 {
133 return(mktemp_internal(path, slen, MKTEMP_FILE));
134 }
135
136 char *
mkdtemp(char * path)137 mkdtemp(char *path)
138 {
139 int error;
140
141 error = mktemp_internal(path, 0, MKTEMP_DIR);
142 return(error ? NULL : path);
143 }
144