1 .\" Copyright (c) 1988, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" This code is derived from software contributed to Berkeley by
5 .\" the American National Standards Committee X3, on Information
6 .\" Processing Systems.
8 .\" Redistribution and use in source and binary forms, with or without
9 .\" modification, are permitted provided that the following conditions
11 .\" 1. Redistributions of source code must retain the above copyright
12 .\" notice, this list of conditions and the following disclaimer.
13 .\" 2. Redistributions in binary form must reproduce the above copyright
14 .\" notice, this list of conditions and the following disclaimer in the
15 .\" documentation and/or other materials provided with the distribution.
16 .\" 4. Neither the name of the University nor the names of its contributors
17 .\" may be used to endorse or promote products derived from this software
18 .\" without specific prior written permission.
20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 .\" @(#)tmpnam.3 8.2 (Berkeley) 11/17/93
33 .\" $FreeBSD: src/lib/libc/stdio/tmpnam.3,v 1.20 2007/03/16 21:46:24 maxim Exp $
34 .\" $DragonFly: src/lib/libc/stdio/tmpnam.3,v 1.4 2008/09/24 19:48:40 swildner Exp $
43 .Nd temporary file routines
51 .Fn tmpnam "char *str"
53 .Fn tempnam "const char *tmpdir" "const char *prefix"
58 returns a pointer to a stream associated with a file descriptor returned
61 The created file is unlinked before
63 returns, causing the file to be automatically deleted when the last
64 reference to it is closed.
65 The file is opened with the access value
67 The file is created in the directory determined by the environment variable
70 The default location if
78 returns a pointer to a file name, in the
81 did not reference an existing file at some indeterminate point in the
84 is defined in the include file
90 the file name is copied to the buffer it references.
91 Otherwise, the file name is copied to a static buffer.
94 returns a pointer to the file name.
96 The buffer referenced by
98 is expected to be at least
102 is defined in the include file
110 but provides the ability to specify the directory which will
111 contain the temporary file and the file name prefix.
113 The environment variable
115 (if set), the argument
123 are tried, in the listed order, as directories in which to store the
130 is used to specify a file name prefix, which will be the
131 first part of the created file name.
135 allocates memory in which to store the file name; the returned pointer
136 may be used as a subsequent argument to
142 returns a pointer to an open file stream on success, and a
152 return a pointer to a file name on success, and a
162 the directory in which the temporary file is stored.
164 is ignored for processes
170 These interfaces are provided from System V and
174 Most historic implementations of these functions provide
175 only a limited number of possible temporary file names
177 before file names will start being recycled.
178 System V implementations of these functions
183 system call to determine whether or not the temporary file
185 This has obvious ramifications for setuid or setgid programs,
186 complicating the portable use of these interfaces in such programs.
190 interface should not be used in software expected to be used on other systems
191 if there is any possibility that the user does not wish the temporary file to
192 be publicly readable and writable.
197 may fail and set the global variable
199 for any of the errors specified for the library functions
209 for any of the errors specified for the library function
217 for any of the errors specified for the library functions
221 .Sh SECURITY CONSIDERATIONS
226 functions are susceptible to a race condition
227 occurring between the selection of the file name
228 and the creation of the file,
229 which allows malicious users
230 to potentially overwrite arbitrary files in the system,
231 depending on the level of privilege of the running program.
232 Additionally, there is no means by which
233 file permissions may be specified.
234 It is strongly suggested that
236 be used in place of these functions.