NetBSD/lib/libc/stdio/mktemp.3

187 lines
4.6 KiB
Groff
Raw Normal View History

1998-07-28 21:11:12 +04:00
.\" $NetBSD: mktemp.3,v 1.13 1998/07/28 17:11:12 mycroft Exp $
.\"
.\" Copyright (c) 1989, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
1993-03-21 12:45:37 +03:00
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)mktemp.3 8.1 (Berkeley) 6/4/93
1993-03-21 12:45:37 +03:00
.\"
1998-07-28 21:11:12 +04:00
.Dd July 28, 1998
1993-03-21 12:45:37 +03:00
.Dt MKTEMP 3
.Os
.Sh NAME
.Nm mktemp ,
1998-07-27 20:41:40 +04:00
.Nm mkstemp ,
.Nm mkdtemp
.Nd make unique temporary file or directory name
1998-02-05 21:45:17 +03:00
.Sh LIBRARY
.Lb libc
1993-03-21 12:45:37 +03:00
.Sh SYNOPSIS
.Fd #include <stdlib.h>
1993-03-21 12:45:37 +03:00
.Ft char *
.Fn mktemp "char *template"
.Ft int
.Fn mkstemp "char *template"
1998-07-27 20:41:40 +04:00
.Ft char *
.Fn mkdtemp "char *template"
1993-03-21 12:45:37 +03:00
.Sh DESCRIPTION
The
.Fn mktemp
function
takes the given file name template and overwrites a portion of it
to create a file name.
This file name is unique and suitable for use
by the application.
The template may be any file name with some number of
.Ql X Ns s
appended
to it, for example
.Pa /tmp/temp.XXXX .
The trailing
.Ql X Ns s
are replaced with the current process number and/or a
unique letter combination.
The number of unique file names
.Fn mktemp
can return depends on the number of
.Ql X Ns s
provided; six
.Ql X Ns s
will
result in
.Fn mktemp
testing roughly 26 ** 6 combinations.
.Pp
The
.Fn mkstemp
function
makes the same replacement to the template and creates the template file,
mode 0600, returning a file descriptor opened for reading and writing.
This avoids the race between testing for a file's existence and opening it
for use.
1998-07-27 20:41:40 +04:00
.Pp
The
.Fn mkdtemp
function
is similar to
.Fn mkstemp ,
but it creates a mode 0700 directory instead and returns the path.
1993-03-21 12:45:37 +03:00
.Sh RETURN VALUES
The
.Fn mktemp
1998-07-27 20:41:40 +04:00
and
.Fn mkdtemp
functions
return a pointer to the template on success and
1993-03-21 12:45:37 +03:00
.Dv NULL
on failure.
The
.Fn mkstemp
function
returns \-1 if no suitable file could be created.
If either call fails an error code is placed in the global variable
.Va errno .
.Sh ERRORS
The
1998-07-27 20:41:40 +04:00
.Fn mktemp ,
1993-03-21 12:45:37 +03:00
.Fn mkstemp
1998-07-27 20:41:40 +04:00
and
.Fn mkdtemp
1993-03-21 12:45:37 +03:00
functions
may set
.Va errno
to one of the following values:
.Bl -tag -width Er
1993-03-21 12:45:37 +03:00
.It Bq Er ENOTDIR
The pathname portion of the template is not an existing directory.
.El
.Pp
The
1998-07-27 20:41:40 +04:00
.Fn mktemp ,
1993-03-21 12:45:37 +03:00
.Fn mkstemp
1998-07-27 20:41:40 +04:00
and
.Fn mkdtemp
1993-03-21 12:45:37 +03:00
functions
may also set
.Va errno
to any value specified by the
.Xr stat 2
function.
.Pp
The
.Fn mkstemp
function
may also set
.Va errno
to any value specified by the
.Xr open 2
function.
1998-07-27 20:41:40 +04:00
.Pp
The
.Fn mkdtemp
function
may also set
.Va errno
to any value specified by the
.Xr mkdir 2
function.
1993-03-21 12:45:37 +03:00
.Sh SEE ALSO
.Xr chmod 2 ,
.Xr getpid 2 ,
.Xr open 2 ,
.Xr stat 2
.Sh HISTORY
A
1993-12-01 21:49:52 +03:00
.Fn mktemp
1993-03-21 12:45:37 +03:00
function appeared in
.At v7 .
1998-07-28 21:11:12 +04:00
.Pp
The
.Fn mkstemp
function appeared in
.Bx 4.4 .
.Pp
The
.Fn mkdtemp
function appeared in
.Nx 1.4 .
.Sh SECURITY CONSIDERATIONS
The use of
.Fn mktemp
should generally be avoided, as a hostile process can exploit a race
condition in the time between the generation of a temporary filename by
.Fn mktemp
and the invoker's use of the temporary name.
1998-07-27 20:41:40 +04:00
A link-time warning will be issued advising the use of
.Fn mkstemp
1998-07-27 20:41:40 +04:00
or
.Fn mkdtemp
instead.