1/*	$OpenBSD: mktemp.c,v 1.35 2014/10/31 15:54:14 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#define MKOTEMP_FLAGS	(O_APPEND | O_CLOEXEC | O_DSYNC | O_RSYNC | O_SYNC)
39
40#ifndef nitems
41#define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
42#endif
43
44static int
45mktemp_internal(char *path, int slen, int mode, int flags)
46{
47	char *start, *cp, *ep;
48	const char tempchars[] = TEMPCHARS;
49	unsigned int tries;
50	struct stat sb;
51	size_t len;
52	int fd;
53
54	len = strlen(path);
55	if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) {
56		errno = EINVAL;
57		return(-1);
58	}
59	ep = path + len - slen;
60
61	for (start = ep; start > path && start[-1] == 'X'; start--)
62		;
63	if (ep - start < MIN_X) {
64		errno = EINVAL;
65		return(-1);
66	}
67
68	if (flags & ~MKOTEMP_FLAGS) {
69		errno = EINVAL;
70		return(-1);
71	}
72	flags |= O_CREAT | O_EXCL | O_RDWR;
73
74	tries = INT_MAX;
75	do {
76		cp = start;
77		do {
78			unsigned short rbuf[16];
79			unsigned int i;
80
81			/*
82			 * Avoid lots of arc4random() calls by using
83			 * a buffer sized for up to 16 Xs at a time.
84			 */
85			arc4random_buf(rbuf, sizeof(rbuf));
86			for (i = 0; i < nitems(rbuf) && cp != ep; i++)
87				*cp++ = tempchars[rbuf[i] % NUM_CHARS];
88		} while (cp != ep);
89
90		switch (mode) {
91		case MKTEMP_NAME:
92			if (lstat(path, &sb) != 0)
93				return(errno == ENOENT ? 0 : -1);
94			break;
95		case MKTEMP_FILE:
96			fd = open(path, flags, S_IRUSR|S_IWUSR);
97			if (fd != -1 || errno != EEXIST)
98				return(fd);
99			break;
100		case MKTEMP_DIR:
101			if (mkdir(path, S_IRUSR|S_IWUSR|S_IXUSR) == 0)
102				return(0);
103			if (errno != EEXIST)
104				return(-1);
105			break;
106		}
107	} while (--tries);
108
109	errno = EEXIST;
110	return(-1);
111}
112
113char *_mktemp(char *);
114
115char *
116_mktemp(char *path)
117{
118	if (mktemp_internal(path, 0, MKTEMP_NAME, 0) == -1)
119		return(NULL);
120	return(path);
121}
122
123__warn_references(mktemp,
124    "warning: mktemp() possibly used unsafely; consider using mkstemp()");
125
126char *
127mktemp(char *path)
128{
129	return(_mktemp(path));
130}
131
132int
133mkostemps(char *path, int slen, int flags)
134{
135	return(mktemp_internal(path, slen, MKTEMP_FILE, flags));
136}
137
138int
139mkstemp(char *path)
140{
141	return(mktemp_internal(path, 0, MKTEMP_FILE, 0));
142}
143
144int
145mkostemp(char *path, int flags)
146{
147	return(mktemp_internal(path, 0, MKTEMP_FILE, flags));
148}
149
150int
151mkstemps(char *path, int slen)
152{
153	return(mktemp_internal(path, slen, MKTEMP_FILE, 0));
154}
155
156char *
157mkdtemp(char *path)
158{
159	int error;
160
161	error = mktemp_internal(path, 0, MKTEMP_DIR, 0);
162	return(error ? NULL : path);
163}
164