TMPNAM
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME
tmpnam, tmpnam_r - create a name for a temporary file
SYNOPSIS
#include <stdio.h>
char *tmpnam(char *s);
char *tmpnam_r(char *s);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
tmpnam_r()
-
- Since glibc 2.19:
-
_DEFAULT_SOURCE
- Up to and including glibc 2.19:
-
_BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
Note:
avoid using these functions; use
mkstemp(3)
or
tmpfile(3)
instead.
The
tmpnam()
function returns a pointer to a string that is a valid filename,
and such that a file with this name did not exist at some point
in time, so that naive programmers may think it
a suitable name for a temporary file.
If the argument
s
is NULL, this name is generated in an internal static buffer
and may be overwritten by the next call to
tmpnam().
If
s
is not NULL, the name is copied to the character array (of length
at least
L_tmpnam)
pointed to by
s
and the value
s
is returned in case of success.
The created pathname has a directory prefix
P_tmpdir.
(Both
L_tmpnam
and
P_tmpdir
are defined in
<stdio.h>,
just like the
TMP_MAX
mentioned below.)
The
tmpnam_r()
function performs the same task as
tmpnam(),
but returns NULL (to indicate an error) if
s
is NULL.
RETURN VALUE
These functions return a pointer to a unique temporary
filename, or NULL if a unique name cannot be generated.
ERRORS
No errors are defined.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
tmpnam()
| Thread safety | MT-Unsafe race:tmpnam/!s
|
|
tmpnam_r()
| Thread safety | MT-Safe
|
CONFORMING TO
tmpnam():
SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
POSIX.1-2008 marks
tmpnam()
as obsolete.
tmpnam_r()
is a nonstandard extension that is also available
on a few other systems.
NOTES
The
tmpnam()
function generates a different string each time it is called,
up to
TMP_MAX
times.
If it is called more than
TMP_MAX
times,
the behavior is implementation defined.
Although these functions generate names that are difficult to guess,
it is nevertheless possible that between the time that
the pathname is returned and the time that the program opens it,
another program might create that pathname using
open(2),
or create it as a symbolic link.
This can lead to security holes.
To avoid such possibilities, use the
open(2)
O_EXCL
flag to open the pathname.
Or better yet, use
mkstemp(3)
or
tmpfile(3).
Portable applications that use threads cannot call
tmpnam()
with a NULL argument if either
_POSIX_THREADS
or
_POSIX_THREAD_SAFE_FUNCTIONS
is defined.
BUGS
Never use these functions.
Use
mkstemp(3)
or
tmpfile(3)
instead.
SEE ALSO
mkstemp(3),
mktemp(3),
tempnam(3),
tmpfile(3)
COLOPHON
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- NOTES
-
- BUGS
-
- SEE ALSO
-
- COLOPHON
-
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