xref: /freebsd/lib/libc/stdio/tmpfile.c (revision 43a5ec4eb41567cc92586503212743d89686d78f)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1990, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Chris Torek.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)tmpfile.c	8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include "namespace.h"
42 #include <sys/types.h>
43 #include <signal.h>
44 #include <unistd.h>
45 #include <errno.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include <paths.h>
50 #include "un-namespace.h"
51 #include "libc_private.h"
52 
53 FILE *
54 tmpfile(void)
55 {
56 	sigset_t set, oset;
57 	FILE *fp;
58 	int fd, sverrno;
59 #define	TRAILER	"tmp.XXXXXX"
60 	char *buf;
61 	const char *tmpdir;
62 
63 	tmpdir = NULL;
64 	if (issetugid() == 0)
65 		tmpdir = getenv("TMPDIR");
66 	if (tmpdir == NULL)
67 		tmpdir = _PATH_TMP;
68 
69 	(void)asprintf(&buf, "%s%s%s", tmpdir,
70 	    (tmpdir[strlen(tmpdir) - 1] == '/') ? "" : "/", TRAILER);
71 	if (buf == NULL)
72 		return (NULL);
73 
74 	sigfillset(&set);
75 	(void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
76 
77 	fd = mkstemp(buf);
78 	if (fd != -1)
79 		(void)unlink(buf);
80 
81 	free(buf);
82 
83 	(void)__libc_sigprocmask(SIG_SETMASK, &oset, NULL);
84 
85 	if (fd == -1)
86 		return (NULL);
87 
88 	if ((fp = fdopen(fd, "w+")) == NULL) {
89 		sverrno = errno;
90 		(void)_close(fd);
91 		errno = sverrno;
92 		return (NULL);
93 	}
94 	return (fp);
95 }
96